draft-ietf-tsvwg-sctpsocket-24.txt   draft-ietf-tsvwg-sctpsocket-25.txt 
Network Working Group R. Stewart Network Working Group R. Stewart
Internet-Draft Huawei Internet-Draft Huawei
Intended status: Informational K. Poon Intended status: Informational M. Tuexen
Expires: April 28, 2011 Oracle Corporation Expires: July 11, 2011 Muenster Univ. of Applied Sciences
M. Tuexen K. Poon
Muenster Univ. of Applied Sciences Oracle Corporation
V. Yasevich
HP
P. Lei P. Lei
Cisco Systems, Inc. Cisco Systems, Inc.
October 25, 2010 V. Yasevich
HP
January 7, 2011
Sockets API Extensions for Stream Control Transmission Protocol (SCTP) Sockets API Extensions for Stream Control Transmission Protocol (SCTP)
draft-ietf-tsvwg-sctpsocket-24.txt draft-ietf-tsvwg-sctpsocket-25.txt
Abstract Abstract
This document describes a mapping of the Stream Control Transmission This document describes a mapping of the Stream Control Transmission
Protocol SCTP into a sockets API. The benefits of this mapping Protocol (SCTP) into a sockets API. The benefits of this mapping
include compatibility for TCP applications, access to new SCTP include compatibility for TCP applications, access to new SCTP
features and a consolidated error and event notification scheme. features and a consolidated error and event notification scheme.
Status of this Memo Status of this Memo
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provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on April 28, 2011. This Internet-Draft will expire on July 11, 2011.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 7 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 7
2. Data Types . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2. Data Types . . . . . . . . . . . . . . . . . . . . . . . . . 8
3. One-to-Many Style Interface . . . . . . . . . . . . . . . . . 8 3. One-to-Many Style Interface . . . . . . . . . . . . . . . . . 8
3.1. Basic Operation . . . . . . . . . . . . . . . . . . . . . 8 3.1. Basic Operation . . . . . . . . . . . . . . . . . . . . . 8
3.1.1. socket() . . . . . . . . . . . . . . . . . . . . . . . 9 3.1.1. socket() . . . . . . . . . . . . . . . . . . . . . . 9
3.1.2. bind() . . . . . . . . . . . . . . . . . . . . . . . . 10 3.1.2. bind() . . . . . . . . . . . . . . . . . . . . . . . 10
3.1.3. listen() . . . . . . . . . . . . . . . . . . . . . . . 11 3.1.3. listen() . . . . . . . . . . . . . . . . . . . . . . 11
3.1.4. sendmsg() and recvmsg() . . . . . . . . . . . . . . . 11 3.1.4. sendmsg() and recvmsg() . . . . . . . . . . . . . . . 12
3.1.5. close() . . . . . . . . . . . . . . . . . . . . . . . 13 3.1.5. close() . . . . . . . . . . . . . . . . . . . . . . . 14
3.1.6. connect() . . . . . . . . . . . . . . . . . . . . . . 14 3.1.6. connect() . . . . . . . . . . . . . . . . . . . . . . 14
3.2. Non-blocking mode . . . . . . . . . . . . . . . . . . . . 14 3.2. Non-blocking mode . . . . . . . . . . . . . . . . . . . . 15
3.3. Special considerations . . . . . . . . . . . . . . . . . . 15 3.3. Special considerations . . . . . . . . . . . . . . . . . 16
4. One-to-One Style Interface . . . . . . . . . . . . . . . . . . 17 4. One-to-One Style Interface . . . . . . . . . . . . . . . . . 18
4.1. Basic Operation . . . . . . . . . . . . . . . . . . . . . 17 4.1. Basic Operation . . . . . . . . . . . . . . . . . . . . . 18
4.1.1. socket() . . . . . . . . . . . . . . . . . . . . . . . 18 4.1.1. socket() . . . . . . . . . . . . . . . . . . . . . . 19
4.1.2. bind() . . . . . . . . . . . . . . . . . . . . . . . . 18 4.1.2. bind() . . . . . . . . . . . . . . . . . . . . . . . 19
4.1.3. listen() . . . . . . . . . . . . . . . . . . . . . . . 19 4.1.3. listen() . . . . . . . . . . . . . . . . . . . . . . 21
4.1.4. accept() . . . . . . . . . . . . . . . . . . . . . . . 20 4.1.4. accept() . . . . . . . . . . . . . . . . . . . . . . 21
4.1.5. connect() . . . . . . . . . . . . . . . . . . . . . . 20 4.1.5. connect() . . . . . . . . . . . . . . . . . . . . . . 22
4.1.6. close() . . . . . . . . . . . . . . . . . . . . . . . 21 4.1.6. close() . . . . . . . . . . . . . . . . . . . . . . . 23
4.1.7. shutdown() . . . . . . . . . . . . . . . . . . . . . . 22 4.1.7. shutdown() . . . . . . . . . . . . . . . . . . . . . 23
4.1.8. sendmsg() and recvmsg() . . . . . . . . . . . . . . . 22 4.1.8. sendmsg() and recvmsg() . . . . . . . . . . . . . . . 24
4.1.9. getpeername() . . . . . . . . . . . . . . . . . . . . 23 4.1.9. getpeername() . . . . . . . . . . . . . . . . . . . . 24
5. Data Structures . . . . . . . . . . . . . . . . . . . . . . . 23 5. Data Structures . . . . . . . . . . . . . . . . . . . . . . . 25
5.1. The msghdr and cmsghdr Structures . . . . . . . . . . . . 23 5.1. The msghdr and cmsghdr Structures . . . . . . . . . . . . 25
5.2. SCTP msg_control Structures . . . . . . . . . . . . . . . 24 5.2. Ancillary Data Considerations and Semantics . . . . . . . 26
5.2.1. SCTP Initiation Structure (SCTP_INIT) . . . . . . . . 25 5.2.1. Multiple Items and Ordering . . . . . . . . . . . . . 26
5.2.2. SCTP Header Information Structure (SCTP_SNDRCV) . . . 26 5.2.2. Accessing and Manipulating Ancillary Data . . . . . . 27
5.2.3. Extended SCTP Header Information Structure 5.2.3. Control Message Buffer Sizing . . . . . . . . . . . . 27
(SCTP_EXTRCV) . . . . . . . . . . . . . . . . . . . . 28 5.3. SCTP msg_control Structures . . . . . . . . . . . . . . . 28
5.2.4. SCTP Send Information Structure (SCTP_SNDINFO) . . . . 30 5.3.1. SCTP Initiation Structure (SCTP_INIT) . . . . . . . . 29
5.2.5. SCTP Receive Information Structure (SCTP_RCVINFO) . . 31 5.3.2. SCTP Header Information Structure (SCTP_SNDRCV) -
5.2.6. SCTP Next Receive Information Structure DEPRECATED . . . . . . . . . . . . . . . . . . . . . 30
(SCTP_NXTINFO) . . . . . . . . . . . . . . . . . . . . 33 5.3.3. Extended SCTP Header Information Structure
5.2.7. SCTP PR-SCTP Information Structure (SCTP_PRINFO) . . . 33 (SCTP_EXTRCV) - DEPRECATED . . . . . . . . . . . . . 33
5.2.8. SCTP AUTH Information Structure (SCTP_AUTHINFO) . . . 34 5.3.4. SCTP Send Information Structure (SCTP_SNDINFO) . . . 34
5.2.9. SCTP Destination Address Structure (IPv4) 5.3.5. SCTP Receive Information Structure (SCTP_RCVINFO) . . 36
(SCTP_DSTADDRV4) . . . . . . . . . . . . . . . . . . . 34 5.3.6. SCTP Next Receive Information Structure
5.2.10. SCTP Destination Address Structure (IPv6) (SCTP_NXTINFO) . . . . . . . . . . . . . . . . . . . 37
(SCTP_DSTADDRV6) . . . . . . . . . . . . . . . . . . . 34 5.3.7. SCTP PR-SCTP Information Structure (SCTP_PRINFO) . . 39
5.3. SCTP Events and Notifications . . . . . . . . . . . . . . 35 5.3.8. SCTP AUTH Information Structure (SCTP_AUTHINFO) . . . 39
5.3.1. SCTP Notification Structure . . . . . . . . . . . . . 35 5.3.9. SCTP Destination Address Structure (IPv4)
5.3.2. SCTP_ASSOC_CHANGE . . . . . . . . . . . . . . . . . . 37 (SCTP_DSTADDRV4) . . . . . . . . . . . . . . . . . . 40
5.3.3. SCTP_PEER_ADDR_CHANGE . . . . . . . . . . . . . . . . 38 5.3.10. SCTP Destination Address Structure (IPv6)
5.3.4. SCTP_REMOTE_ERROR . . . . . . . . . . . . . . . . . . 39 (SCTP_DSTADDRV6) . . . . . . . . . . . . . . . . . . 40
5.3.5. SCTP_SEND_FAILED . . . . . . . . . . . . . . . . . . . 40 6. SCTP Events and Notifications . . . . . . . . . . . . . . . . 40
5.3.6. SCTP_SHUTDOWN_EVENT . . . . . . . . . . . . . . . . . 41 6.1. SCTP Notification Structure . . . . . . . . . . . . . . . 41
5.3.7. SCTP_ADAPTATION_INDICATION . . . . . . . . . . . . . . 42 6.1.1. SCTP_ASSOC_CHANGE . . . . . . . . . . . . . . . . . . 43
5.3.8. SCTP_PARTIAL_DELIVERY_EVENT . . . . . . . . . . . . . 42 6.1.2. SCTP_PEER_ADDR_CHANGE . . . . . . . . . . . . . . . . 44
5.3.9. SCTP_AUTHENTICATION_EVENT . . . . . . . . . . . . . . 43 6.1.3. SCTP_REMOTE_ERROR . . . . . . . . . . . . . . . . . . 46
5.3.10. SCTP_SENDER_DRY_EVENT . . . . . . . . . . . . . . . . 44 6.1.4. SCTP_SEND_FAILED - DEPRECATED . . . . . . . . . . . . 46
5.3.11. SCTP_NOTIFICATIONS_STOPPED_EVENT . . . . . . . . . . . 45 6.1.5. SCTP_SHUTDOWN_EVENT . . . . . . . . . . . . . . . . . 48
5.3.12. SCTP_SEND_FAILED_EVENT . . . . . . . . . . . . . . . . 45 6.1.6. SCTP_ADAPTATION_INDICATION . . . . . . . . . . . . . 48
5.4. Ancillary Data Considerations and Semantics . . . . . . . 46 6.1.7. SCTP_PARTIAL_DELIVERY_EVENT . . . . . . . . . . . . . 49
5.4.1. Multiple Items and Ordering . . . . . . . . . . . . . 46 6.1.8. SCTP_AUTHENTICATION_EVENT . . . . . . . . . . . . . . 50
5.4.2. Accessing and Manipulating Ancillary Data . . . . . . 47 6.1.9. SCTP_SENDER_DRY_EVENT . . . . . . . . . . . . . . . . 51
5.4.3. Control Message Buffer Sizing . . . . . . . . . . . . 47 6.1.10. SCTP_NOTIFICATIONS_STOPPED_EVENT . . . . . . . . . . 51
6. Common Operations for Both Styles . . . . . . . . . . . . . . 48 6.1.11. SCTP_SEND_FAILED_EVENT . . . . . . . . . . . . . . . 52
6.1. send(), recv(), sendto(), and recvfrom() . . . . . . . . . 48 6.2. Notification Interest Options . . . . . . . . . . . . . . 53
6.2. setsockopt() and getsockopt() . . . . . . . . . . . . . . 50 6.2.1. SCTP_EVENTS option - DEPRECATED . . . . . . . . . . . 53
6.3. read() and write() . . . . . . . . . . . . . . . . . . . . 51 6.2.2. SCTP_EVENT option . . . . . . . . . . . . . . . . . . 55
6.4. getsockname() . . . . . . . . . . . . . . . . . . . . . . 51 7. Common Operations for Both Styles . . . . . . . . . . . . . . 56
6.5. Implicit Association Setup . . . . . . . . . . . . . . . . 52 7.1. send(), recv(), sendto(), and recvfrom() . . . . . . . . 56
7. Socket Options . . . . . . . . . . . . . . . . . . . . . . . . 52 7.2. setsockopt() and getsockopt() . . . . . . . . . . . . . . 58
7.1. Read / Write Options . . . . . . . . . . . . . . . . . . . 54 7.3. read() and write() . . . . . . . . . . . . . . . . . . . 59
7.1.1. Retransmission Timeout Parameters (SCTP_RTOINFO) . . . 54 7.4. getsockname() . . . . . . . . . . . . . . . . . . . . . . 59
7.1.2. Association Parameters (SCTP_ASSOCINFO) . . . . . . . 55 7.5. Implicit Association Setup . . . . . . . . . . . . . . . 60
7.1.3. Initialization Parameters (SCTP_INITMSG) . . . . . . . 57 8. Socket Options . . . . . . . . . . . . . . . . . . . . . . . 61
7.1.4. SO_LINGER . . . . . . . . . . . . . . . . . . . . . . 57 8.1. Read / Write Options . . . . . . . . . . . . . . . . . . 62
7.1.5. SCTP_NODELAY . . . . . . . . . . . . . . . . . . . . . 57 8.1.1. Retransmission Timeout Parameters (SCTP_RTOINFO) . . 62
7.1.6. SO_RCVBUF . . . . . . . . . . . . . . . . . . . . . . 58 8.1.2. Association Parameters (SCTP_ASSOCINFO) . . . . . . . 63
7.1.7. SO_SNDBUF . . . . . . . . . . . . . . . . . . . . . . 58 8.1.3. Initialization Parameters (SCTP_INITMSG) . . . . . . 65
7.1.8. Automatic Close of Associations (SCTP_AUTOCLOSE) . . . 58 8.1.4. SO_LINGER . . . . . . . . . . . . . . . . . . . . . . 65
7.1.9. Set Primary Address (SCTP_PRIMARY_ADDR) . . . . . . . 58 8.1.5. SCTP_NODELAY . . . . . . . . . . . . . . . . . . . . 65
7.1.10. Set Adaptation Layer Indicator 8.1.6. SO_RCVBUF . . . . . . . . . . . . . . . . . . . . . . 66
(SCTP_ADAPTATION_LAYER) . . . . . . . . . . . . . . . 59 8.1.7. SO_SNDBUF . . . . . . . . . . . . . . . . . . . . . . 66
7.1.11. Enable/Disable Message Fragmentation 8.1.8. Automatic Close of Associations (SCTP_AUTOCLOSE) . . 66
(SCTP_DISABLE_FRAGMENTS) . . . . . . . . . . . . . . . 59 8.1.9. Set Primary Address (SCTP_PRIMARY_ADDR) . . . . . . . 67
7.1.12. Peer Address Parameters (SCTP_PEER_ADDR_PARAMS) . . . 59 8.1.10. Set Adaptation Layer Indicator
7.1.13. Set Default Send Parameters (SCTP_ADAPTATION_LAYER) . . . . . . . . . . . . . . . 67
(SCTP_DEFAULT_SEND_PARAM) . . . . . . . . . . . . . . 61 8.1.11. Enable/Disable Message Fragmentation
7.1.14. Set Notification and Ancillary Events (SCTP_EVENTS) . 62 (SCTP_DISABLE_FRAGMENTS) . . . . . . . . . . . . . . 67
7.1.15. Set/Clear IPv4 Mapped Addresses 8.1.12. Peer Address Parameters (SCTP_PEER_ADDR_PARAMS) . . . 68
(SCTP_I_WANT_MAPPED_V4_ADDR) . . . . . . . . . . . . . 62 8.1.13. Set Default Send Parameters
7.1.16. Get or Set the Maximum Fragmentation Size (SCTP_DEFAULT_SEND_PARAM) - DEPRECATED . . . . . . . 70
(SCTP_MAXSEG) . . . . . . . . . . . . . . . . . . . . 62 8.1.14. Set Notification and Ancillary Events
7.1.17. Get or Set the List of Supported HMAC Identifiers (SCTP_EVENTS) - DEPRECATED . . . . . . . . . . . . . 70
(SCTP_HMAC_IDENT) . . . . . . . . . . . . . . . . . . 63 8.1.15. Set/Clear IPv4 Mapped Addresses
7.1.18. Get or Set the Active Shared Key (SCTP_I_WANT_MAPPED_V4_ADDR) . . . . . . . . . . . . 71
(SCTP_AUTH_ACTIVE_KEY) . . . . . . . . . . . . . . . . 64 8.1.16. Get or Set the Maximum Fragmentation Size
7.1.19. Get or Set Delayed SACK Timer (SCTP_DELAYED_SACK) . . 64 (SCTP_MAXSEG) . . . . . . . . . . . . . . . . . . . . 71
7.1.20. Get or Set Fragmented Interleave 8.1.17. Get or Set the List of Supported HMAC Identifiers
(SCTP_FRAGMENT_INTERLEAVE) . . . . . . . . . . . . . . 65 (SCTP_HMAC_IDENT) . . . . . . . . . . . . . . . . . . 72
7.1.21. Set or Get the SCTP Partial Delivery Point 8.1.18. Get or Set the Active Shared Key
(SCTP_PARTIAL_DELIVERY_POINT) . . . . . . . . . . . . 66 (SCTP_AUTH_ACTIVE_KEY) . . . . . . . . . . . . . . . 72
7.1.22. Set or Get the Use of Extended Receive Info 8.1.19. Get or Set Delayed SACK Timer (SCTP_DELAYED_SACK) . . 73
(SCTP_USE_EXT_RCVINFO) . . . . . . . . . . . . . . . . 67 8.1.20. Get or Set Fragmented Interleave
7.1.23. Set or Get the Auto ASCONF Flag (SCTP_AUTO_ASCONF) . . 67 (SCTP_FRAGMENT_INTERLEAVE) . . . . . . . . . . . . . 74
7.1.24. Set or Get the Maximum Burst (SCTP_MAX_BURST) . . . . 67 8.1.21. Set or Get the SCTP Partial Delivery Point
7.1.25. Set or Get the Default Context (SCTP_CONTEXT) . . . . 68 (SCTP_PARTIAL_DELIVERY_POINT) . . . . . . . . . . . . 75
7.1.26. Enable or Disable Explicit EOR Marking 8.1.22. Set or Get the Use of Extended Receive Info
(SCTP_EXPLICIT_EOR) . . . . . . . . . . . . . . . . . 68 (SCTP_USE_EXT_RCVINFO) - DEPRECATED . . . . . . . . . 75
7.1.27. Enable SCTP Port Reusage (SCTP_REUSE_PORT) . . . . . . 68 8.1.23. Set or Get the Auto ASCONF Flag (SCTP_AUTO_ASCONF) . 76
7.1.28. Set Notification Event (SCTP_EVENT) . . . . . . . . . 69 8.1.24. Set or Get the Maximum Burst (SCTP_MAX_BURST) . . . . 76
7.1.29. Enable or Disable the Delivery of SCTP_RCVINFO as 8.1.25. Set or Get the Default Context (SCTP_CONTEXT) . . . . 77
Ancillary Data (SCTP_RECVRCVINFO) . . . . . . . . . . 69 8.1.26. Enable or Disable Explicit EOR Marking
7.1.30. Enable or Disable the Delivery of SCTP_NXTINFO as (SCTP_EXPLICIT_EOR) . . . . . . . . . . . . . . . . . 77
Ancillary Data (SCTP_RECVNXTINFO) . . . . . . . . . . 69 8.1.27. Enable SCTP Port Reusage (SCTP_REUSE_PORT) . . . . . 77
7.1.31. Set Default Send Parameters (SCTP_DEFAULT_SNDINFO) . . 69 8.1.28. Set Notification Event (SCTP_EVENT) . . . . . . . . . 78
7.2. Read-Only Options . . . . . . . . . . . . . . . . . . . . 70 8.1.29. Enable or Disable the Delivery of SCTP_RCVINFO as
7.2.1. Association Status (SCTP_STATUS) . . . . . . . . . . . 70 Ancillary Data (SCTP_RECVRCVINFO) . . . . . . . . . . 78
7.2.2. Peer Address Information (SCTP_GET_PEER_ADDR_INFO) . . 71 8.1.30. Enable or Disable the Delivery of SCTP_NXTINFO as
7.2.3. Get the List of Chunks the Peer Requires to be Ancillary Data (SCTP_RECVNXTINFO) . . . . . . . . . . 78
Authenticated (SCTP_PEER_AUTH_CHUNKS) . . . . . . . . 72 8.1.31. Set Default Send Parameters (SCTP_DEFAULT_SNDINFO) . 78
7.2.4. Get the List of Chunks the Local Endpoint Requires 8.2. Read-Only Options . . . . . . . . . . . . . . . . . . . . 79
to be Authenticated (SCTP_LOCAL_AUTH_CHUNKS) . . . . . 72 8.2.1. Association Status (SCTP_STATUS) . . . . . . . . . . 79
7.2.5. Get the Current Number of Associations 8.2.2. Peer Address Information (SCTP_GET_PEER_ADDR_INFO) . 80
(SCTP_GET_ASSOC_NUMBER) . . . . . . . . . . . . . . . 73 8.2.3. Get the List of Chunks the Peer Requires to be
7.2.6. Get the Current Identifiers of Associations Authenticated (SCTP_PEER_AUTH_CHUNKS) . . . . . . . . 82
(SCTP_GET_ASSOC_ID_LIST) . . . . . . . . . . . . . . . 73 8.2.4. Get the List of Chunks the Local Endpoint Requires
7.3. Write-Only Options . . . . . . . . . . . . . . . . . . . . 74 to be Authenticated (SCTP_LOCAL_AUTH_CHUNKS) . . . . 82
7.3.1. Set Peer Primary Address 8.2.5. Get the Current Number of Associations
(SCTP_SET_PEER_PRIMARY_ADDR) . . . . . . . . . . . . . 74 (SCTP_GET_ASSOC_NUMBER) . . . . . . . . . . . . . . . 83
7.3.2. Add a Chunk That Must Be Authenticated 8.2.6. Get the Current Identifiers of Associations
(SCTP_AUTH_CHUNK) . . . . . . . . . . . . . . . . . . 74 (SCTP_GET_ASSOC_ID_LIST) . . . . . . . . . . . . . . 83
7.3.3. Set a Shared Key (SCTP_AUTH_KEY) . . . . . . . . . . . 75 8.3. Write-Only Options . . . . . . . . . . . . . . . . . . . 84
7.3.4. Deactivate a Shared Key (SCTP_AUTH_DEACTIVATE_KEY) . . 75 8.3.1. Set Peer Primary Address
7.3.5. Delete a Shared Key (SCTP_AUTH_DELETE_KEY) . . . . . . 76 (SCTP_SET_PEER_PRIMARY_ADDR) . . . . . . . . . . . . 84
7.4. Ancillary Data and Notification Interest Options . . . . . 76 8.3.2. Add a Chunk That Must Be Authenticated
8. New Functions . . . . . . . . . . . . . . . . . . . . . . . . 79 (SCTP_AUTH_CHUNK) . . . . . . . . . . . . . . . . . . 84
8.1. sctp_bindx() . . . . . . . . . . . . . . . . . . . . . . . 79 8.3.3. Set a Shared Key (SCTP_AUTH_KEY) . . . . . . . . . . 85
8.2. sctp_peeloff() . . . . . . . . . . . . . . . . . . . . . . 81 8.3.4. Deactivate a Shared Key (SCTP_AUTH_DEACTIVATE_KEY) . 85
8.3. sctp_getpaddrs() . . . . . . . . . . . . . . . . . . . . . 82 8.3.5. Delete a Shared Key (SCTP_AUTH_DELETE_KEY) . . . . . 86
8.4. sctp_freepaddrs() . . . . . . . . . . . . . . . . . . . . 82 9. New Functions . . . . . . . . . . . . . . . . . . . . . . . . 86
8.5. sctp_getladdrs() . . . . . . . . . . . . . . . . . . . . . 83 9.1. sctp_bindx() . . . . . . . . . . . . . . . . . . . . . . 87
8.6. sctp_freeladdrs() . . . . . . . . . . . . . . . . . . . . 83 9.2. sctp_peeloff() . . . . . . . . . . . . . . . . . . . . . 88
8.7. sctp_sendmsg() . . . . . . . . . . . . . . . . . . . . . . 83 9.3. sctp_getpaddrs() . . . . . . . . . . . . . . . . . . . . 89
8.8. sctp_recvmsg() . . . . . . . . . . . . . . . . . . . . . . 84 9.4. sctp_freepaddrs() . . . . . . . . . . . . . . . . . . . . 90
8.9. sctp_connectx() . . . . . . . . . . . . . . . . . . . . . 85 9.5. sctp_getladdrs() . . . . . . . . . . . . . . . . . . . . 90
8.10. sctp_send() . . . . . . . . . . . . . . . . . . . . . . . 86 9.6. sctp_freeladdrs() . . . . . . . . . . . . . . . . . . . . 90
8.11. sctp_sendx() . . . . . . . . . . . . . . . . . . . . . . . 87 9.7. sctp_sendmsg() - DEPRECATED . . . . . . . . . . . . . . . 91
8.12. sctp_recvv() . . . . . . . . . . . . . . . . . . . . . . . 88 9.8. sctp_recvmsg() - DEPRECATED . . . . . . . . . . . . . . . 92
8.13. sctp_sendv() . . . . . . . . . . . . . . . . . . . . . . . 89 9.9. sctp_connectx() . . . . . . . . . . . . . . . . . . . . . 93
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 90 9.10. sctp_send() - DEPRECATED . . . . . . . . . . . . . . . . 94
10. Security Considerations . . . . . . . . . . . . . . . . . . . 90 9.11. sctp_sendx() - DEPRECATED . . . . . . . . . . . . . . . . 95
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 91 9.12. sctp_recvv() . . . . . . . . . . . . . . . . . . . . . . 96
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 91 9.13. sctp_sendv() . . . . . . . . . . . . . . . . . . . . . . 98
12.1. Normative References . . . . . . . . . . . . . . . . . . . 91 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 100
12.2. Informative References . . . . . . . . . . . . . . . . . . 92 11. Security Considerations . . . . . . . . . . . . . . . . . . . 101
Appendix A. One-to-One Style Code Example . . . . . . . . . . . . 92 12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 101
Appendix B. One-to-Many Style Code Example . . . . . . . . . . . 97 13. References . . . . . . . . . . . . . . . . . . . . . . . . . 101
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 99 13.1. Normative References . . . . . . . . . . . . . . . . . . 101
13.2. Informative References . . . . . . . . . . . . . . . . . 102
Appendix A. One-to-One Style Code Example . . . . . . . . . . . 102
Appendix B. One-to-Many Style Code Example . . . . . . . . . . . 105
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 110
1. Introduction 1. Introduction
The sockets API has provided a standard mapping of the Internet The sockets API has provided a standard mapping of the Internet
Protocol suite to many operating systems. Both TCP [RFC0793] and UDP Protocol suite to many operating systems. Both TCP [RFC0793] and UDP
[RFC0768] have benefited from this standard representation and access [RFC0768] have benefited from this standard representation and access
method across many diverse platforms. SCTP is a new protocol that method across many diverse platforms. SCTP is a new protocol that
provides many of the characteristics of TCP but also incorporates provides many of the characteristics of TCP but also incorporates
semantics more akin to UDP. This document defines a method to map semantics more akin to UDP. This document defines a method to map
the existing sockets API for use with SCTP, providing both a base for the existing sockets API for use with SCTP, providing both a base for
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Protocol suite to many operating systems. Both TCP [RFC0793] and UDP Protocol suite to many operating systems. Both TCP [RFC0793] and UDP
[RFC0768] have benefited from this standard representation and access [RFC0768] have benefited from this standard representation and access
method across many diverse platforms. SCTP is a new protocol that method across many diverse platforms. SCTP is a new protocol that
provides many of the characteristics of TCP but also incorporates provides many of the characteristics of TCP but also incorporates
semantics more akin to UDP. This document defines a method to map semantics more akin to UDP. This document defines a method to map
the existing sockets API for use with SCTP, providing both a base for the existing sockets API for use with SCTP, providing both a base for
access to new features and compatibility so that most existing TCP access to new features and compatibility so that most existing TCP
applications can be migrated to SCTP with few (if any) changes. applications can be migrated to SCTP with few (if any) changes.
There are three basic design objectives: There are three basic design objectives:
1. Maintain consistency with existing sockets APIs: We define a 1. Maintain consistency with existing sockets APIs: We define a
sockets mapping for SCTP that is consistent with other sockets sockets mapping for SCTP that is consistent with other sockets
API protocol mappings (for instance UDP, TCP, IPv4, and IPv6). API protocol mappings (for instance UDP, TCP, IPv4, and IPv6).
2. Support a one-to-many style interface: This set of semantics is 2. Support a one-to-many style interface: This set of semantics is
similar to that defined for connection-less protocols, such as similar to that defined for connection-less protocols, such as
UDP. A one-to-many style SCTP socket should be able to control UDP. A one-to-many style SCTP socket should be able to control
multiple SCTP associations. This is similar to a UDP socket, multiple SCTP associations. This is similar to a UDP socket,
which can communicate with many peer endpoints. Each of these which can communicate with many peer endpoints. Each of these
associations is assigned an association ID so that an application associations is assigned an association ID so that an application
can use the ID to differentiate them. Note that SCTP is can use the ID to differentiate them. Note that SCTP is
connection-oriented in nature, and it does not support broadcast connection-oriented in nature, and it does not support broadcast
or multicast communications, as UDP does. or multicast communications, as UDP does.
3. Support a one-to-one style interface: This interface supports a 3. Support a one-to-one style interface: This interface supports a
similar semantics as sockets for connection-oriented protocols, similar semantics as sockets for connection-oriented protocols,
such as TCP. A one-to-one style SCTP socket should only control such as TCP. A one-to-one style SCTP socket should only control
one SCTP association. One purpose of defining this interface is one SCTP association. One purpose of defining this interface is
to allow existing applications built on other connection-oriented to allow existing applications built on other connection-oriented
protocols be ported to use SCTP with very little effort. protocols to be ported to use SCTP with very little effort.
Developers familiar with these semantics can easily adapt to Developers familiar with these semantics can easily adapt to
SCTP. Another purpose is to make sure that existing mechanisms SCTP. Another purpose is to make sure that existing mechanisms
in most operating systems that support sockets, such as select(), in most operating systems that support sockets, such as select(),
should continue to work with this style of socket. Extensions should continue to work with this style of socket. Extensions
are added to this mapping to provide mechanisms to exploit new are added to this mapping to provide mechanisms to exploit new
features of SCTP. features of SCTP.
Goals 2 and 3 are not compatible, so this document defines two modes Goals 2 and 3 are not compatible, so this document defines two modes
of mapping, namely the one-to-many style mapping and the one-to-one of mapping, namely the one-to-many style mapping and the one-to-one
style mapping. These two modes share some common data structures and style mapping. These two modes share some common data structures and
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programming styles. Note that all new SCTP features can be used with programming styles. Note that all new SCTP features can be used with
both styles of socket. The decision on which one to use depends both styles of socket. The decision on which one to use depends
mainly on the nature of applications. mainly on the nature of applications.
A mechanism is defined to extract a one-to-many style SCTP A mechanism is defined to extract a one-to-many style SCTP
association into a one-to-one style socket. association into a one-to-one style socket.
Some of the SCTP mechanisms cannot be adequately mapped to an Some of the SCTP mechanisms cannot be adequately mapped to an
existing socket interface. In some cases, it is more desirable to existing socket interface. In some cases, it is more desirable to
have a new interface instead of using existing socket calls. have a new interface instead of using existing socket calls.
Section 8 of this document describes these new interfaces. Section 9 of this document describes these new interfaces.
2. Data Types 2. Data Types
Whenever possible, data types from Draft 6.6 (March 1997) of POSIX Whenever possible, data types from Draft 6.6 (March 1997) of POSIX
1003.1g are used: uintN_t means an unsigned integer of exactly N bits 1003.1g are used: uintN_t means an unsigned integer of exactly N bits
(e.g. uint16_t). This document also assumes the argument data types (e.g. uint16_t). This document also assumes the argument data types
from 1003.1g when possible (e.g. the final argument to setsockopt() from 1003.1g when possible (e.g. the final argument to setsockopt()
is a size_t value). Whenever buffer sizes are specified, the POSIX is a size_t value). Whenever buffer sizes are specified, the POSIX
1003.1 size_t data type is used. 1003.1 size_t data type is used.
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3. One-to-Many Style Interface 3. One-to-Many Style Interface
In the one-to-many style interface there is a 1 to many relationship In the one-to-many style interface there is a 1 to many relationship
between sockets and associations. between sockets and associations.
3.1. Basic Operation 3.1. Basic Operation
A typical server in this style uses the following socket calls in A typical server in this style uses the following socket calls in
sequence to prepare an endpoint for servicing requests: sequence to prepare an endpoint for servicing requests:
o socket() o socket()
o bind() o bind()
o listen() o listen()
o recvmsg() o recvmsg()
o sendmsg() o sendmsg()
o close() o close()
A typical client uses the following calls in sequence to setup an A typical client uses the following calls in sequence to setup an
association with a server to request services: association with a server to request services:
o socket() o socket()
o sendmsg() o sendmsg()
o recvmsg() o recvmsg()
o close() o close()
In this style, by default, all the associations connected to the In this style, by default, all the associations connected to the
endpoint are represented with a single socket. Each association is endpoint are represented with a single socket. Each association is
assigned an association ID (type is sctp_assoc_t) so that an assigned an association ID (type is sctp_assoc_t) so that an
application can use it to differentiate between them. In some application can use it to differentiate among them. In some
implementations, the peer endpoints' addresses can also be used for implementations, the peer endpoints' addresses can also be used for
this purpose. But this is not required for performance reasons. If this purpose. But this is not required for performance reasons. If
an implementation does not support using addresses to differentiate an implementation does not support using addresses to differentiate
between different associations, the sendto() call can only be used to between different associations, the sendto() call can only be used to
setup an association implicitly. It cannot be used to send data to setup an association implicitly. It cannot be used to send data to
an established association as the association ID cannot be specified. an established association as the association ID cannot be specified.
Once an association ID is assigned to an SCTP association, that ID Once an association ID is assigned to an SCTP association, that ID
will not be reused until the application explicitly terminates the will not be reused until the application explicitly terminates the
association. The resources belonging to that association will not be use of the association. The resources belonging to that association
freed until that happens. This is similar to the close() operation will not be freed until that happens. This is similar to the close()
on a normal socket. The only exception is when the SCTP_AUTOCLOSE operation on a normal socket. The only exception is when the
option (section 7.1.8) is set. In this case, after the association SCTP_AUTOCLOSE option (section 7.1.8) is set. In this case, after
is terminated gracefully and automatically, the association ID the association is terminated gracefully and automatically, the
assigned to it can be reused. All applications using this option association ID assigned to it can be reused. All applications using
should be aware of this to avoid the possible problem of sending data this option should be aware of this to avoid the possible problem of
to an incorrect peer endpoint. sending data to an incorrect peer endpoint.
If the server or client wishes to branch an existing association off If the server or client wishes to branch an existing association off
to a separate socket, it is required to call sctp_peeloff() and to to a separate socket, it is required to call sctp_peeloff() and to
specify the association identifier. The sctp_peeloff() call will specify the association identifier. The sctp_peeloff() call will
return a new socket which can then be used with recv() and send() return a new one-to-one style socket which can then be used with
functions for message passing. See Section 8.2 for more on branched- recv() and send() functions for message passing. See Section 9.2 for
off associations. The returned socket is a one-to-one style socket. more on branched-off associations.
Once an association is branched off to a separate socket, it becomes Once an association is branched off to a separate socket, it becomes
completely separated from the original socket. All subsequent completely separated from the original socket. All subsequent
control and data operations to that association must be done through control and data operations to that association must be done through
the new socket. For example, the close operation on the original the new socket. For example, the close operation on the original
socket will not terminate any associations that have been branched socket will not terminate any associations that have been branched
off to a different socket. off to a different socket.
One-to-many style socket calls are discussed in more detail in the One-to-many style socket calls are discussed in more detail in the
following subsections. following subsections.
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Using the PF_INET domain indicates the creation of an endpoint which Using the PF_INET domain indicates the creation of an endpoint which
can use only IPv4 addresses, while PF_INET6 creates an endpoint which can use only IPv4 addresses, while PF_INET6 creates an endpoint which
can use both IPv6 and IPv4 addresses. can use both IPv6 and IPv4 addresses.
3.1.2. bind() 3.1.2. bind()
Applications use bind() to specify which local address and port the Applications use bind() to specify which local address and port the
SCTP endpoint should associate itself with. SCTP endpoint should associate itself with.
An SCTP endpoint can be associated with multiple addresses. To do An SCTP endpoint can be associated with multiple addresses. To do
this, sctp_bindx() is introduced in Section 8.1 to help applications this, sctp_bindx() is introduced in Section 9.1 to help applications
do the job of associating multiple addresses. But note that an do the job of associating multiple addresses. But note that an
endpoint can only be associated with one local port. endpoint can only be associated with one local port.
These addresses associated with a socket are the eligible transport These addresses associated with a socket are the eligible transport
addresses for the endpoint to send and receive data. The endpoint addresses for the endpoint to send and receive data. The endpoint
will also present these addresses to its peers during the association will also present these addresses to its peers during the association
initialization process, see [RFC4960]. initialization process, see [RFC4960].
After calling bind(), if the endpoint wishes to accept new After calling bind(), if the endpoint wishes to accept new
associations on the socket, it must call listen() (see associations on the socket, it must call listen() (see
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an optimal address set of the available interfaces. If the IPv4 an optimal address set of the available interfaces. If the IPv4
sin_port or IPv6 sin6_port is set to 0, the operating system will sin_port or IPv6 sin6_port is set to 0, the operating system will
choose an ephemeral port for the endpoint. choose an ephemeral port for the endpoint.
If a bind() is not called prior to a sendmsg() call that initiates a If a bind() is not called prior to a sendmsg() call that initiates a
new association, the system picks an ephemeral port and will choose new association, the system picks an ephemeral port and will choose
an address set equivalent to binding with a wildcard address. One of an address set equivalent to binding with a wildcard address. One of
those addresses will be the primary address for the association. those addresses will be the primary address for the association.
This automatically enables the multi-homing capability of SCTP. This automatically enables the multi-homing capability of SCTP.
The completion of this bind() process does not allow the SCTP
endpoint to accept inbound SCTP association requests. Until a
listen() system call, described below, is performed on the socket,
the SCTP endpoint will promptly reject an inbound SCTP INIT request
with an SCTP ABORT.
3.1.3. listen() 3.1.3. listen()
By default, a one-to-many style socket does not accept new By default, a one-to-many style socket does not accept new
association requests. An application uses listen() to mark a socket association requests. An application uses listen() to mark a socket
as being able to accept new associations. as being able to accept new associations.
The function prototype is The function prototype is
int listen(int sd, int listen(int sd,
int backlog); int backlog);
and the arguments are and the arguments are
sd: The socket descriptor of the endpoint. sd: The socket descriptor of the endpoint.
backlog: If backlog is non-zero, enable listening else disable
backlog: If backlog is non-zero, enable listening, else disable
listening. listening.
It returns 0 on success and -1 in case of an error. It returns 0 on success and -1 in case of an error.
Note that one-to-many style socket consumers do not need to call Note that one-to-many style socket consumers do not need to call
accept to retrieve new associations. Calling accept() on a one-to- accept to retrieve new associations. Calling accept() on a one-to-
many style socket should return EOPNOTSUPP. Rather, new associations many style socket should return EOPNOTSUPP. Rather, new associations
are accepted automatically, and notifications of the new associations are accepted automatically, and notifications of the new associations
are delivered via recvmsg() with the SCTP_ASSOC_CHANGE event (if are delivered via recvmsg() with the SCTP_ASSOC_CHANGE event (if
these notifications are enabled). Clients will typically not call these notifications are enabled). Clients will typically not call
listen(), so that they can be assured that only actively initiated listen(), so that they can be assured that only actively initiated
associations are on the socket. Server or peer-to-peer sockets, on associations are possible on the socket. Server or peer-to-peer
the other hand, will always accept new associations, so a well- sockets, on the other hand, will always accept new associations, so a
written application using server one-to-many style sockets must be well-written application using server one-to-many style sockets must
prepared to handle new associations from unwanted peers. be prepared to handle new associations from unwanted peers.
Also note that the SCTP_ASSOC_CHANGE event provides the association Also note that the SCTP_ASSOC_CHANGE event provides the association
ID for a new association, so if applications wish to use the ID for a new association, so if applications wish to use the
association ID as input to other socket calls, they should ensure association ID as a parameter to other socket calls, they should
that the SCTP_ASSOC_CHANGE event is enabled. ensure that the SCTP_ASSOC_CHANGE event is enabled.
3.1.4. sendmsg() and recvmsg() 3.1.4. sendmsg() and recvmsg()
An application uses the sendmsg() and recvmsg() call to transmit data An application uses the sendmsg() and recvmsg() call to transmit data
to and receive data from its peer. to and receive data from its peer.
The function prototypes are The function prototypes are
ssize_t sendmsg(int sd, ssize_t sendmsg(int sd,
const struct msghdr *message, const struct msghdr *message,
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data is used to specify the sent behavior, such as the SCTP stream data is used to specify the sent behavior, such as the SCTP stream
number to use. When receiving, the ancillary data is used to number to use. When receiving, the ancillary data is used to
describe the received data, such as the SCTP stream sequence number describe the received data, such as the SCTP stream sequence number
of the message. of the message.
When sending user data with sendmsg(), the msg_name field in the When sending user data with sendmsg(), the msg_name field in the
msghdr structure will be filled with one of the transport addresses msghdr structure will be filled with one of the transport addresses
of the intended receiver. If there is no existing association of the intended receiver. If there is no existing association
between the sender and the intended receiver, the sender's SCTP stack between the sender and the intended receiver, the sender's SCTP stack
will set up a new association and then send the user data (see will set up a new association and then send the user data (see
Section 6.5 for more on implicit association setup). If sendmsg() is Section 7.5 for more on implicit association setup). If sendmsg() is
called with no data and there is no existing association, a new one called with no data and there is no existing association, a new one
will be established. The SCTP_INIT type ancillary data can be used will be established. The SCTP_INIT type ancillary data can be used
to change some of the parameters used to set up a new association. to change some of the parameters used to set up a new association.
If sendmsg() is called with NULL data, and there is no existing If sendmsg() is called with NULL data, and there is no existing
association but the SCTP_ABORT or SCTP_EOF flags are set, then -1 is association but the SCTP_ABORT or SCTP_EOF flags are set, then -1 is
returned and errno is set to EINVAL. Sending a message using returned and errno is set to EINVAL. Sending a message using
sendmsg() is atomic unless explicit EOR marking is enabled on the sendmsg() is atomic unless explicit EOR marking is enabled on the
socket specified by sd (see Section 7.1.26). socket specified by sd (see Section 8.1.26).
If a peer sends a SHUTDOWN, an SCTP_SHUTDOWN_EVENT notification will If a peer sends a SHUTDOWN, an SCTP_SHUTDOWN_EVENT notification will
be delivered if that notification has been enabled, and no more data be delivered if that notification has been enabled, and no more data
can be sent to that association. Any attempt to send more data will can be sent to that association. Any attempt to send more data will
cause sendmsg() to return with an ESHUTDOWN error. Note that the cause sendmsg() to return with an ESHUTDOWN error. Note that the
socket is still open for reading at this point so it is possible to socket is still open for reading at this point so it is possible to
retrieve notifications. retrieve notifications.
When receiving a user message with recvmsg(), the msg_name field in When receiving a user message with recvmsg(), the msg_name field in
the msghdr structure will be populated with the source transport the msghdr structure will be populated with the source transport
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receive a data message, MSG_EOR will not be set in msg_flags. receive a data message, MSG_EOR will not be set in msg_flags.
Successive reads will consume more of the same message until the Successive reads will consume more of the same message until the
entire message has been delivered, and MSG_EOR will be set. entire message has been delivered, and MSG_EOR will be set.
If the SCTP stack is running low on buffers, it may partially deliver If the SCTP stack is running low on buffers, it may partially deliver
a message. In this case, MSG_EOR will not be set, and more calls to a message. In this case, MSG_EOR will not be set, and more calls to
recvmsg() will be necessary to completely consume the message. Only recvmsg() will be necessary to completely consume the message. Only
one message at a time can be partially delivered in any stream. The one message at a time can be partially delivered in any stream. The
socket option SCTP_FRAGMENT_INTERLEAVE controls various aspects of socket option SCTP_FRAGMENT_INTERLEAVE controls various aspects of
what interlacing of messages occurs for both the one-to-one and the what interlacing of messages occurs for both the one-to-one and the
one-to-many model sockets. Please consult Section 7.1.20 for further one-to-many model sockets. Please consult Section 8.1.20 for further
details on message delivery options. details on message delivery options.
3.1.5. close() 3.1.5. close()
Applications use close() to perform graceful shutdown (as described Applications use close() to perform graceful shutdown (as described
in Section 10.1 of [RFC4960]) on all the associations currently in Section 10.1 of [RFC4960]) on all the associations currently
represented by a one-to-many style socket. represented by a one-to-many style socket.
The function prototype is The function prototype is
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Applications use close() to perform graceful shutdown (as described Applications use close() to perform graceful shutdown (as described
in Section 10.1 of [RFC4960]) on all the associations currently in Section 10.1 of [RFC4960]) on all the associations currently
represented by a one-to-many style socket. represented by a one-to-many style socket.
The function prototype is The function prototype is
int close(int sd); int close(int sd);
and the argument is and the argument is
sd: The socket descriptor of the associations to be closed. sd: The socket descriptor of the associations to be closed.
0 is returned on success and -1 in case of an error. 0 is returned on success and -1 in case of an error.
To gracefully shutdown a specific association represented by the one- To gracefully shutdown a specific association represented by the one-
to-many style socket, an application should use the sendmsg() call, to-many style socket, an application should use the sendmsg() call,
and include the SCTP_EOF flag. A user may optionally terminate an and include the SCTP_EOF flag. A user may optionally terminate an
association non-gracefully by sending with the SCTP_ABORT flag set association non-gracefully by sending with the SCTP_ABORT flag set
and possibly passing a user specified abort code in the data field. and possibly passing a user specified abort code in the data field.
Both flags SCTP_EOF and SCTP_ABORT are passed with ancillary data Both flags SCTP_EOF and SCTP_ABORT are passed with ancillary data
(see Section 5.2.2) in the sendmsg() call. (see Section 5.3.2) in the sendmsg() call.
If sd in the close() call is a branched-off socket representing only If sd in the close() call is a branched-off socket representing only
one association, the shutdown is performed on that association only. one association, the shutdown is performed on that association only.
3.1.6. connect() 3.1.6. connect()
An application may use the connect() call in the one-to-many style to An application may use the connect() call in the one-to-many style to
initiate an association without sending data. initiate an association without sending data.
The function prototype is The function prototype is
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Some SCTP application may wish to avoid being blocked when calling a Some SCTP application may wish to avoid being blocked when calling a
socket interface function. socket interface function.
Once a bind() and/or subsequent sctp_bindx() calls are complete on a Once a bind() and/or subsequent sctp_bindx() calls are complete on a
one-to-many style socket, an application may set the non-blocking one-to-many style socket, an application may set the non-blocking
option by a fcntl() (such as O_NONBLOCK). After setting the socket option by a fcntl() (such as O_NONBLOCK). After setting the socket
to non-blocking mode, the sendmsg() function returns immediately. to non-blocking mode, the sendmsg() function returns immediately.
The success or failure of sending the data message (with possible The success or failure of sending the data message (with possible
SCTP_INITMSG ancillary data) will be signaled by the SCTP_INITMSG ancillary data) will be signaled by the
SCTP_ASSOC_CHANGE event with SCTP_COMM_UP or CANT_START_ASSOC. If SCTP_ASSOC_CHANGE event with SCTP_COMM_UP or SCTP_CANT_START_ASSOC.
user data could not be sent (due to a CANT_START_ASSOC), the sender
will also receive an SCTP_SEND_FAILED event. Events can be received If user data could not be sent (due to a SCTP_CANT_START_ASSOC), the
by the user calling recvmsg(). A server (having called listen()) is sender will also receive an SCTP_SEND_FAILED_EVENT event. Events can
also notified of an association up event by the reception of an be received by the user calling recvmsg(). A server (having called
SCTP_ASSOC_CHANGE with SCTP_COMM_UP via the calling of recvmsg() and listen()) is also notified of an association up event by the
possibly the reception of the first data message. reception of an SCTP_ASSOC_CHANGE with SCTP_COMM_UP via the calling
of recvmsg() and possibly the reception of the first data message.
To shutdown the association gracefully, the user must call sendmsg() To shutdown the association gracefully, the user must call sendmsg()
with no data and with the SCTP_EOF flag set. The function returns with no data and with the SCTP_EOF flag set. The function returns
immediately, and completion of the graceful shutdown is indicated by immediately, and completion of the graceful shutdown is indicated by
an SCTP_ASSOC_CHANGE notification of type SHUTDOWN_COMPLETE (see an SCTP_ASSOC_CHANGE notification of type SHUTDOWN_COMPLETE (see
Section 5.3.2). Note that this can also be done using the Section 6.1.1). Note that this can also be done using the
sctp_send() call described in Section 8.10. sctp_send() call described in Section 9.10.
An application is recommended to use caution when using select() (or An application is recommended to use caution when using select() (or
poll()) for writing on a one-to-many style socket. The reason being poll()) for writing on a one-to-many style socket. The reason being
that the interpretation of select on write is implementation that the interpretation of select on write is implementation
specific. Generally a positive return on a select on write would specific. Generally a positive return on a select on write would
only indicate that one of the associations represented by the one-to- only indicate that one of the associations represented by the one-to-
many socket is writable. An application that writes after the many socket is writable. An application that writes after the
select() returns may still block since the association that was select() returns may still block since the association that was
writeable is not the destination association of the write call. writeable is not the destination association of the write call.
Likewise select() (or poll()) for reading from a one-to-many socket Likewise select() (or poll()) for reading from a one-to-many socket
will only return an indication that one of the associations will only return an indication that one of the associations
represented by the socket has data to be read. represented by the socket has data to be read.
An application that wishes to know that a particular association is An application that wishes to know that a particular association is
ready for reading or writing should either use the one-to-one style ready for reading or writing should either use the one-to-one style
or use the sctp_peeloff() (see Section 8.2) function to separate the or use the sctp_peeloff() (see Section 9.2) function to separate the
association of interest from the one-to-many socket. association of interest from the one-to-many socket.
Note some implementations may have an extended select call such as Note some implementations may have an extended select call such as
epoll or kqueue that may escape this limitation and allow a select on epoll or kqueue that may escape this limitation and allow a select on
a specific association of a one-to-many socket, but this is an a specific association of a one-to-many socket, but this is an
implementation specific detail that a portable application cannot implementation specific detail that a portable application cannot
count on. depend on.
3.3. Special considerations 3.3. Special considerations
The fact that a one-to-many style socket can provide access to many The fact that a one-to-many style socket can provide access to many
SCTP associations through a single socket descriptor has important SCTP associations through a single socket descriptor has important
implications for both application programmers and system programmers implications for both application programmers and system programmers
implementing this API. A key issue is how buffer space inside the implementing this API. A key issue is how buffer space inside the
sockets layer is managed. Because this implementation detail sockets layer is managed. Because this implementation detail
directly affects how application programmers must write their code to directly affects how application programmers must write their code to
ensure correct operation and portability, this section provides some ensure correct operation and portability, this section provides some
skipping to change at page 18, line 43 skipping to change at page 19, line 49
Using the PF_INET domain indicates the creation of an endpoint which Using the PF_INET domain indicates the creation of an endpoint which
can use only IPv4 addresses, while PF_INET6 creates an endpoint which can use only IPv4 addresses, while PF_INET6 creates an endpoint which
can use both IPv6 and IPv4 addresses. can use both IPv6 and IPv4 addresses.
4.1.2. bind() 4.1.2. bind()
Applications use bind() to specify which local address and port the Applications use bind() to specify which local address and port the
SCTP endpoint should associate itself with. SCTP endpoint should associate itself with.
An SCTP endpoint can be associated with multiple addresses. To do An SCTP endpoint can be associated with multiple addresses. To do
this, sctp_bindx() is introduced in Section 8.1 to help applications this, sctp_bindx() is introduced in Section 9.1 to help applications
do the job of associating multiple addresses. But note that an do the job of associating multiple addresses. But note that an
endpoint can only be associated with one local port. endpoint can only be associated with one local port.
These addresses associated with a socket are the eligible transport These addresses associated with a socket are the eligible transport
addresses for the endpoint to send and receive data. The endpoint addresses for the endpoint to send and receive data. The endpoint
will also present these addresses to its peers during the association will also present these addresses to its peers during the association
initialization process, see [RFC4960]. initialization process, see [RFC4960].
The function prototype of bind() is The function prototype of bind() is
int bind(int sd, int bind(int sd,
struct sockaddr *addr, struct sockaddr *addr,
socklen_t addrlen); socklen_t addrlen);
and the arguments are and the arguments are
sd: The socket descriptor returned by socket(). sd: The socket descriptor returned by socket().
addr: The address structure (struct sockaddr_in for an IPv4 address addr: The address structure (struct sockaddr_in for an IPv4 address
or struct sockaddr_in6 for an IPv6 address, see [RFC3493]). or struct sockaddr_in6 for an IPv6 address, see [RFC3493]).
addrlen: The size of the address structure. addrlen: The size of the address structure.
If sd is an IPv4 socket, the address passed must be an IPv4 address. If sd is an IPv4 socket, the address passed must be an IPv4 address.
If sd is an IPv6 socket, the address passed can either be an IPv4 or If sd is an IPv6 socket, the address passed can either be an IPv4 or
an IPv6 address. an IPv6 address.
Applications cannot call bind() multiple times to associate multiple Applications cannot call bind() multiple times to associate multiple
addresses to the endpoint. After the first call to bind(), all addresses to the endpoint. After the first call to bind(), all
subsequent calls will return an error. subsequent calls will return an error.
skipping to change at page 20, line 46 skipping to change at page 22, line 16
Applications use connect() to initiate an association to a peer. Applications use connect() to initiate an association to a peer.
The function prototype is The function prototype is
int connect(int sd, int connect(int sd,
const struct sockaddr *addr, const struct sockaddr *addr,
socklen_t addrlen); socklen_t addrlen);
and the arguments are and the arguments are
sd: The socket descriptor of the endpoint. sd: The socket descriptor of the endpoint.
addr: The peer's (struct sockaddr_in for an IPv4 address or struct addr: The peer's (struct sockaddr_in for an IPv4 address or struct
sockaddr_in6 for an IPv6 address, see [RFC3493]) address. sockaddr_in6 for an IPv6 address, see [RFC3493]) address.
addrlen: The size of the address. addrlen: The size of the address.
It returns 0 on success and -1 on error. It returns 0 on success and -1 on error.
This operation corresponds to the ASSOCIATE primitive described in This operation corresponds to the ASSOCIATE primitive described in
Section 10.1 of [RFC4960]. Section 10.1 of [RFC4960].
The number of outbound streams the new association has is stack The number of outbound streams the new association has is stack
dependent. Applications can use the SCTP_INITMSG option described in dependent. Applications can use the SCTP_INITMSG option described in
Section 7.1.3 before connecting to change the number of outbound Section 8.1.3 before connecting to change the number of outbound
streams. streams.
If a bind() is not called prior to the connect() call, the system If a bind() is not called prior to the connect() call, the system
picks an ephemeral port and will choose an address set equivalent to picks an ephemeral port and will choose an address set equivalent to
binding with INADDR_ANY and IN6ADDR_ANY_INIT for IPv4 and IPv6 socket binding with INADDR_ANY and IN6ADDR_ANY_INIT for IPv4 and IPv6 socket
respectively. One of the addresses will be the primary address for respectively. One of the addresses will be the primary address for
the association. This automatically enables the multi-homing the association. This automatically enables the multi-homing
capability of SCTP. capability of SCTP.
Note that SCTP allows data exchange, similar to T/TCP [RFC1644], Note that SCTP allows data exchange, similar to T/TCP [RFC1644],
skipping to change at page 22, line 21 skipping to change at page 23, line 40
to SCTP may need to recode sections that use shutdown(). (Note that to SCTP may need to recode sections that use shutdown(). (Note that
it is possible to achieve the same results as half close in SCTP it is possible to achieve the same results as half close in SCTP
using SCTP streams.) using SCTP streams.)
The function prototype is The function prototype is
int shutdown(int sd, int shutdown(int sd,
int how); int how);
and the arguments are and the arguments are
sd: The socket descriptor of the association to be closed. sd: The socket descriptor of the association to be closed.
how: Specifies the type of shutdown. The values are as follows: how: Specifies the type of shutdown. The values are as follows:
SHUT_RD: Disables further receive operations. No SCTP protocol SHUT_RD: Disables further receive operations. No SCTP protocol
action is taken. action is taken.
SHUT_WR: Disables further send operations, and initiates the SCTP SHUT_WR: Disables further send operations, and initiates the SCTP
shutdown sequence. shutdown sequence.
SHUT_RDWR: Disables further send and receive operations and SHUT_RDWR: Disables further send and receive operations and
initiates the SCTP shutdown sequence. initiates the SCTP shutdown sequence.
It returns 0 on success and -1 in case of an error. It returns 0 on success and -1 in case of an error.
The major difference between SCTP and TCP shutdown() is that SCTP The major difference between SCTP and TCP shutdown() is that SCTP
SHUT_WR initiates immediate and full protocol shutdown, whereas TCP SHUT_WR initiates immediate and full protocol shutdown, whereas TCP
SHUT_WR causes TCP to go into the half closed state. SHUT_RD behaves SHUT_WR causes TCP to go into the half closed state. SHUT_RD behaves
the same for SCTP as TCP. The purpose of SCTP SHUT_WR is to close the same for SCTP as TCP. The purpose of SCTP SHUT_WR is to close
the SCTP association while still leaving the socket descriptor open. the SCTP association while still leaving the socket descriptor open.
This allows the caller to receive back any data which SCTP is unable This allows the caller to receive back any data which SCTP is unable
to deliver (see Section 5.3.5 for more information) and receive event to deliver (see Section 6.1.4 for more information) and receive event
notifications. notifications.
To perform the ABORT operation described in [RFC4960] Section 10.1, To perform the ABORT operation described in [RFC4960] Section 10.1,
an application can use the socket option SO_LINGER. It is described an application can use the socket option SO_LINGER. It is described
in Section 7.1.4. in Section 8.1.4.
4.1.8. sendmsg() and recvmsg() 4.1.8. sendmsg() and recvmsg()
With a one-to-one style socket, the application can also use With a one-to-one style socket, the application can also use
sendmsg() and recvmsg() to transmit data to and receive data from its sendmsg() and recvmsg() to transmit data to and receive data from its
peer. The semantics is similar to those used in the one-to-many peer. The semantics is similar to those used in the one-to-many
style (see Section 3.1.3), with the following differences: style (see Section 3.1.3), with the following differences:
1. When sending, the msg_name field in the msghdr is not used to 1. When sending, the msg_name field in the msghdr is not used to
specify the intended receiver, rather it is used to indicate a specify the intended receiver, rather it is used to indicate a
preferred peer address if the sender wishes to discourage the preferred peer address if the sender wishes to discourage the
stack from sending the message to the primary address of the stack from sending the message to the primary address of the
receiver. If the socket is connected and the transport address receiver. If the socket is connected and the transport address
given is not part of the current association, the data will not given is not part of the current association, the data will not
be sent and an SCTP_SEND_FAILED event will be delivered to the be sent and an SCTP_SEND_FAILED_EVENT event will be delivered to
application if send failure events are enabled. the application if send failure events are enabled.
2. Using sendmsg() on a non-connected one-to-one style socket for 2. Using sendmsg() on a non-connected one-to-one style socket for
implicit connection setup may or may not work depending on the implicit connection setup may or may not work depending on the
SCTP implementation. SCTP implementation.
4.1.9. getpeername() 4.1.9. getpeername()
Applications use getpeername() to retrieve the primary socket address Applications use getpeername() to retrieve the primary socket address
of the peer. This call is for TCP compatibility, and is not multi- of the peer. This call is for TCP compatibility, and is not multi-
homed. It may not work with one-to-many style sockets depending on homed. It may not work with one-to-many style sockets depending on
the implementation. See Section 8.3 for a multi-homed style version the implementation. See Section 9.3 for a multi-homed style version
of the call. of the call.
The function prototype is The function prototype is
int getpeername(int sd, int getpeername(int sd,
struct sockaddr *address, struct sockaddr *address,
socklen_t *len); socklen_t *len);
and the arguments are: and the arguments are:
sd: The socket descriptor to be queried. sd: The socket descriptor to be queried.
address: On return, the peer primary address is stored in this address: On return, the peer primary address is stored in this
buffer. If the socket is an IPv4 socket, the address will be buffer. If the socket is an IPv4 socket, the address will be
IPv4. If the socket is an IPv6 socket, the address will be either IPv4. If the socket is an IPv6 socket, the address will be either
an IPv6 or IPv4 address. an IPv6 or IPv4 address.
len: The caller should set the length of address here. On return, len: The caller should set the length of address here. On return,
this is set to the length of the returned address. this is set to the length of the returned address.
It returns 0 on success and -1 in case of an error. It returns 0 on success and -1 in case of an error.
If the actual length of the address is greater than the length of the If the actual length of the address is greater than the length of the
supplied sockaddr structure, the stored address will be truncated. supplied sockaddr structure, the stored address will be truncated.
5. Data Structures 5. Data Structures
This section discusses important data structures which are specific This section discusses important data structures which are specific
to SCTP and are used with sendmsg() and recvmsg() calls to control to SCTP and are used with sendmsg() and recvmsg() calls to control
SCTP endpoint operations and to access ancillary information and SCTP endpoint operations and to access ancillary information and
skipping to change at page 24, line 14 skipping to change at page 26, line 9
the application to set and get various control information from the the application to set and get various control information from the
SCTP endpoint. SCTP endpoint.
The msghdr and the related cmsghdr structures are defined and The msghdr and the related cmsghdr structures are defined and
discussed in detail in [RFC3542]. They are defined as: discussed in detail in [RFC3542]. They are defined as:
struct msghdr { struct msghdr {
void *msg_name; /* ptr to socket address structure */ void *msg_name; /* ptr to socket address structure */
socklen_t msg_namelen; /* size of socket address structure */ socklen_t msg_namelen; /* size of socket address structure */
struct iovec *msg_iov; /* scatter/gather array */ struct iovec *msg_iov; /* scatter/gather array */
size_t msg_iovlen; /* # elements in msg_iov */ int msg_iovlen; /* # elements in msg_iov */
void *msg_control; /* ancillary data */ void *msg_control; /* ancillary data */
socklen_t msg_controllen; /* ancillary data buffer length */ socklen_t msg_controllen; /* ancillary data buffer length */
int msg_flags; /* flags on received message */ int msg_flags; /* flags on received message */
}; };
struct cmsghdr { struct cmsghdr {
socklen_t cmsg_len; /* #bytes, including this header */ socklen_t cmsg_len; /* #bytes, including this header */
int cmsg_level; /* originating protocol */ int cmsg_level; /* originating protocol */
int cmsg_type; /* protocol-specific type */ int cmsg_type; /* protocol-specific type */
/* followed by unsigned char cmsg_data[]; */ /* followed by unsigned char cmsg_data[]; */
}; };
In the msghdr structure, the usage of msg_name has been discussed in In the msghdr structure, the usage of msg_name has been discussed in
previous sections (see Section 3.1.3 and Section 4.1.8). previous sections (see Section 3.1.3 and Section 4.1.8).
The scatter/gather buffers, or I/O vectors (pointed to by the msg_iov The scatter/gather buffers, or I/O vectors (pointed to by the msg_iov
field) are treated by SCTP as a single user message for both field) are treated by SCTP as a single user message for both
sendmsg() and recvmsg(). sendmsg() and recvmsg().
SCTP stack uses the ancillary data (msg_control field) to communicate
the attributes, such as SCTP_RCVINFO, of the message stored in
msg_iov to the socket end point. The different ancillary data types
are described in Section 5.3.
The msg_flags are not used when sending a message with sendmsg(). The msg_flags are not used when sending a message with sendmsg().
If a notification has arrived, recvmsg() will return the notification If a notification has arrived, recvmsg() will return the notification
with the MSG_NOTIFICATION flag set in msg_flags. If the in msg_iov field and set MSG_NOTIFICATION flag in msg_flags. If the
MSG_NOTIFICATION flag is not set, recvmsg() will return data. See MSG_NOTIFICATION flag is not set, recvmsg() will return data. See
Section 5.3 for more information about notifications. Section 6 for more information about notifications.
If all portions of a data frame or notification have been read, If all portions of a data frame or notification have been read,
recvmsg() will return with MSG_EOR set in msg_flags. recvmsg() will return with MSG_EOR set in msg_flags.
5.2. SCTP msg_control Structures 5.2. Ancillary Data Considerations and Semantics
Programming with ancillary socket data (msg_control) contains some
subtleties and pitfalls, which are discussed below.
5.2.1. Multiple Items and Ordering
Multiple ancillary data items may be included in any call to
sendmsg() or recvmsg(); these may include multiple SCTP or non-SCTP,
such as IP level items, or both.
The ordering of ancillary data items (either by SCTP or another
protocol) is not significant and is implementation-dependent, so
applications must not depend on any ordering.
SCTP_SNDRCV/SCTP_SNDINFO/SCTP_RCVINFO type ancillary data always
correspond to the data in the msghdr's msg_iov member. There can be
only one single such type ancillary data for each sendmsg() or
recvmsg() call.
5.2.2. Accessing and Manipulating Ancillary Data
Applications can infer the presence of data or ancillary data by
examining the msg_iovlen and msg_controllen msghdr members,
respectively.
Implementations may have different padding requirements for ancillary
data, so portable applications should make use of the macros
CMSG_FIRSTHDR, CMSG_NXTHDR, CMSG_DATA, CMSG_SPACE, and CMSG_LEN. See
[RFC3542] and the SCTP implementation's documentation for more
information. The following is an example, from [RFC3542],
demonstrating the use of these macros to access ancillary data:
struct msghdr msg;
struct cmsghdr *cmsgptr;
/* fill in msg */
/* call recvmsg() */
for (cmsgptr = CMSG_FIRSTHDR(&msg); cmsgptr != NULL;
cmsgptr = CMSG_NXTHDR(&msg, cmsgptr)) {
if (cmsgptr->cmsg_level == ... && cmsgptr->cmsg_type == ... ) {
u_char *ptr;
ptr = CMSG_DATA(cmsgptr);
/* process data pointed to by ptr */
}
}
5.2.3. Control Message Buffer Sizing
The information conveyed via SCTP_SNDRCV/SCTP_SNDINFO/SCTP_RCVINFO
ancillary data will often be fundamental to the correct and sane
operation of the sockets application. This is particularly true of
the one-to-many semantics, but also of the one-to-one semantics. For
example, if an application needs to send and receive data on
different SCTP streams, SCTP_SNDRCV/SCTP_SNDINFO/SCTP_RCVINFO
ancillary data is indispensable.
Given that some ancillary data is critical, and that multiple
ancillary data items may appear in any order, applications should be
carefully written to always provide a large enough buffer to contain
all possible ancillary data that can be presented by recvmsg(). If
the buffer is too small, and crucial data is truncated, it may pose a
fatal error condition.
Thus, it is essential that applications be able to deterministically
calculate the maximum required buffer size to pass to recvmsg(). One
constraint imposed on this specification that makes this possible is
that all ancillary data definitions are of a fixed length. One way
to calculate the maximum required buffer size might be to take the
sum the sizes of all enabled ancillary data item structures, as
calculated by CMSG_SPACE. For example, if we enabled
SCTP_SNDRCV_INFO and IPV6_RECVPKTINFO [RFC3542], we would calculate
and allocate the buffer size as follows:
size_t total;
void *buf;
total = CMSG_SPACE(sizeof(struct sctp_sndrcvinfo)) +
CMSG_SPACE(sizeof(struct in6_pktinfo));
buf = malloc(total);
We could then use this buffer (buf) for msg_control on each call to
recvmsg() and be assured that we would not lose any ancillary data to
truncation.
5.3. SCTP msg_control Structures
A key element of all SCTP specific socket extensions is the use of A key element of all SCTP specific socket extensions is the use of
ancillary data to specify and access SCTP specific data via the ancillary data to specify and access SCTP specific data via the
struct msghdr's msg_control member used in sendmsg() and recvmsg(). struct msghdr's msg_control member used in sendmsg() and recvmsg().
Fine-grained control over initialization and sending parameters are Fine-grained control over initialization and sending parameters are
handled with ancillary data. handled with ancillary data.
Each ancillary data item is proceeded by a struct cmsghdr (see Each ancillary data item is proceeded by a struct cmsghdr (see
Section 5.1), which defines the function and purpose of the data Section 5.1), which defines the function and purpose of the data
contained in the cmsg_data[] member. contained in the cmsg_data[] member.
By default on either style socket, SCTP will pass no ancillary data; By default on either style socket, SCTP will pass no ancillary data;
Specific ancillary data items can be enabled with socket options Specific ancillary data items can be enabled with socket options
defined for SCTP; see Section 7.4. defined for SCTP; see Section 6.2.
Note that all ancillary types are fixed length; see Section 5.4 for Note that all ancillary types are fixed length; see Section 5.2 for
further discussion on this. These data structures use struct further discussion on this. These data structures use struct
sockaddr_storage (defined in [RFC3493]) as a portable, fixed length sockaddr_storage (defined in [RFC3493]) as a portable, fixed length
address format. address format.
Other protocols may also provide ancillary data to the socket layer Other protocols may also provide ancillary data to the socket layer
consumer. These ancillary data items from other protocols may consumer. These ancillary data items from other protocols may
intermingle with SCTP data. For example, the IPv6 socket API intermingle with SCTP data. For example, the IPv6 socket API
definitions ([RFC3542] and [RFC3493]) define a number of ancillary definitions ([RFC3542] and [RFC3493]) define a number of ancillary
data items. If a socket API consumer enables delivery of both SCTP data items. If a socket API consumer enables delivery of both SCTP
and IPv6 ancillary data, they both may appear in the same msg_control and IPv6 ancillary data, they both may appear in the same msg_control
buffer in any order. An application may thus need to handle other buffer in any order. An application may thus need to handle other
types of ancillary data besides those passed by SCTP. types of ancillary data besides those passed by SCTP.
The sockets application must provide a buffer large enough to The sockets application must provide a buffer large enough to
accommodate all ancillary data provided via recvmsg(). If the buffer accommodate all ancillary data provided via recvmsg(). If the buffer
is not large enough, the ancillary data will be truncated and the is not large enough, the ancillary data will be truncated and the
msghdr's msg_flags will include MSG_CTRUNC. msghdr's msg_flags will include MSG_CTRUNC.
5.2.1. SCTP Initiation Structure (SCTP_INIT) 5.3.1. SCTP Initiation Structure (SCTP_INIT)
This cmsghdr structure provides information for initializing new SCTP This cmsghdr structure provides information for initializing new SCTP
associations with sendmsg(). The SCTP_INITMSG socket option uses associations with sendmsg(). The SCTP_INITMSG socket option uses
this same data structure. This structure is not used for recvmsg(). this same data structure. This structure is not used for recvmsg().
+--------------+-----------+---------------------+ +--------------+-----------+---------------------+
| cmsg_level | cmsg_type | cmsg_data[] | | cmsg_level | cmsg_type | cmsg_data[] |
+--------------+-----------+---------------------+ +--------------+-----------+---------------------+
| IPPROTO_SCTP | SCTP_INIT | struct sctp_initmsg | | IPPROTO_SCTP | SCTP_INIT | struct sctp_initmsg |
+--------------+-----------+---------------------+ +--------------+-----------+---------------------+
skipping to change at page 26, line 4 skipping to change at page 29, line 44
+--------------+-----------+---------------------+ +--------------+-----------+---------------------+
The sctp_initmsg structure is defined below: The sctp_initmsg structure is defined below:
struct sctp_initmsg { struct sctp_initmsg {
uint16_t sinit_num_ostreams; uint16_t sinit_num_ostreams;
uint16_t sinit_max_instreams; uint16_t sinit_max_instreams;
uint16_t sinit_max_attempts; uint16_t sinit_max_attempts;
uint16_t sinit_max_init_timeo; uint16_t sinit_max_init_timeo;
}; };
sinit_num_ostreams: This is an integer number representing the sinit_num_ostreams: This is an integer number representing the
number of streams that the application wishes to be able to send number of streams that the application wishes to be able to send
to. This number is confirmed in the SCTP_COMM_UP notification and to. This number is confirmed in the SCTP_COMM_UP notification and
must be verified since it is a negotiated number with the remote must be verified since it is a negotiated number with the remote
endpoint. The default value of 0 indicates to use the endpoint endpoint. The default value of 0 indicates to use the endpoint
default value. default value.
sinit_max_instreams: This value represents the maximum number of sinit_max_instreams: This value represents the maximum number of
inbound streams the application is prepared to support. This inbound streams the application is prepared to support. This
value is bounded by the actual implementation. In other words the value is bounded by the actual implementation. In other words the
user may be able to support more streams than the Operating user may be able to support more streams than the Operating
System. In such a case, the Operating System limit overrides the System. In such a case, the Operating System limit overrides the
value requested by the user. The default value of 0 indicates to value requested by the user. The default value of 0 indicates to
use the endpoints default value. use the endpoints default value.
sinit_max_attempts: This integer specifies how many attempts the sinit_max_attempts: This integer specifies how many attempts the
SCTP endpoint should make at resending the INIT. This value SCTP endpoint should make at resending the INIT. This value
overrides the system SCTP 'Max.Init.Retransmits' value. The overrides the system SCTP 'Max.Init.Retransmits' value. The
default value of 0 indicates to use the endpoints default value. default value of 0 indicates to use the endpoints default value.
This is normally set to the system's default 'Max.Init.Retransmit' This is normally set to the system's default 'Max.Init.Retransmit'
value. value.
sinit_max_init_timeo: This value represents the largest Time-Out or sinit_max_init_timeo: This value represents the largest Time-Out or
RTO value (in milliseconds) to use in attempting an INIT. RTO value (in milliseconds) to use in attempting an INIT.
Normally the 'RTO.Max' is used to limit the doubling of the RTO Normally the 'RTO.Max' is used to limit the doubling of the RTO
upon timeout. For the INIT message this value may override upon timeout. For the INIT message this value may override
'RTO.Max'. This value must not influence 'RTO.Max' during data 'RTO.Max'. This value must not influence 'RTO.Max' during data
transmission and is only used to bound the initial setup time. A transmission and is only used to bound the initial setup time. A
default value of 0 indicates to use the endpoints default value. default value of 0 indicates to use the endpoints default value.
This is normally set to the system's 'RTO.Max' value (60 seconds). This is normally set to the system's 'RTO.Max' value (60 seconds).
5.2.2. SCTP Header Information Structure (SCTP_SNDRCV) 5.3.2. SCTP Header Information Structure (SCTP_SNDRCV) - DEPRECATED
This cmsghdr structure specifies SCTP options for sendmsg() and This cmsghdr structure specifies SCTP options for sendmsg() and
describes SCTP header information about a received message through describes SCTP header information about a received message through
recvmsg(). This structure mixes the send and receive path. recvmsg(). This structure mixes the send and receive path.
SCTP_SNDINFO described in Section 5.2.4 and SCTP_RCVINFO described in SCTP_SNDINFO described in Section 5.3.4 and SCTP_RCVINFO described in
Section 5.2.5 split this information. These structures should be Section 5.3.5 split this information. These structures should be
used, when possible, since SCTP_SNDRCV is deprecated. used, when possible, since SCTP_SNDRCV is deprecated.
+--------------+-------------+------------------------+ +--------------+-------------+------------------------+
| cmsg_level | cmsg_type | cmsg_data[] | | cmsg_level | cmsg_type | cmsg_data[] |
+--------------+-------------+------------------------+ +--------------+-------------+------------------------+
| IPPROTO_SCTP | SCTP_SNDRCV | struct sctp_sndrcvinfo | | IPPROTO_SCTP | SCTP_SNDRCV | struct sctp_sndrcvinfo |
+--------------+-------------+------------------------+ +--------------+-------------+------------------------+
The sctp_sndrcvinfo structure is defined below: The sctp_sndrcvinfo structure is defined below:
struct sctp_sndrcvinfo { struct sctp_sndrcvinfo {
uint16_t sinfo_stream; uint16_t sinfo_stream;
uint16_t sinfo_ssn; uint16_t sinfo_ssn;
uint16_t sinfo_flags; uint16_t sinfo_flags;
uint32_t sinfo_ppid; uint32_t sinfo_ppid;
uint32_t sinfo_context; uint32_t sinfo_context;
uint32_t sinfo_pr_value; uint32_t sinfo_timetolive;
uint32_t sinfo_tsn; uint32_t sinfo_tsn;
uint32_t sinfo_cumtsn; uint32_t sinfo_cumtsn;
sctp_assoc_t sinfo_assoc_id; sctp_assoc_t sinfo_assoc_id;
}; };
sinfo_stream: For recvmsg() the SCTP stack places the message's sinfo_stream: For recvmsg() the SCTP stack places the message's
stream number in this value. For sendmsg() this value holds the stream number in this value. For sendmsg() this value holds the
stream number that the application wishes to send this message to. stream number that the application wishes to send this message to.
If a sender specifies an invalid stream number an error indication If a sender specifies an invalid stream number an error indication
is returned and the call fails. is returned and the call fails.
skipping to change at page 27, line 22 skipping to change at page 31, line 22
uint32_t sinfo_tsn; uint32_t sinfo_tsn;
uint32_t sinfo_cumtsn; uint32_t sinfo_cumtsn;
sctp_assoc_t sinfo_assoc_id; sctp_assoc_t sinfo_assoc_id;
}; };
sinfo_stream: For recvmsg() the SCTP stack places the message's sinfo_stream: For recvmsg() the SCTP stack places the message's
stream number in this value. For sendmsg() this value holds the stream number in this value. For sendmsg() this value holds the
stream number that the application wishes to send this message to. stream number that the application wishes to send this message to.
If a sender specifies an invalid stream number an error indication If a sender specifies an invalid stream number an error indication
is returned and the call fails. is returned and the call fails.
sinfo_ssn: For recvmsg() this value contains the stream sequence sinfo_ssn: For recvmsg() this value contains the stream sequence
number that the remote endpoint placed in the DATA chunk. For number that the remote endpoint placed in the DATA chunk. For
fragmented messages this is the same number for all deliveries of fragmented messages this is the same number for all deliveries of
the message (if more than one recvmsg() is needed to read the the message (if more than one recvmsg() is needed to read the
message). The sendmsg() call will ignore this parameter. message). The sendmsg() call will ignore this parameter.
sinfo_flags: This field may contain any of the following flags and sinfo_flags: This field may contain any of the following flags and
is composed of a bitwise OR of these values. is composed of a bitwise OR of these values.
recvmsg() flags: recvmsg() flags:
SCTP_UNORDERED: This flag is present when the message was sent SCTP_UNORDERED: This flag is present when the message was sent
un-ordered. un-ordered.
sendmsg() flags: sendmsg() flags:
SCTP_UNORDERED: This flag requests the un-ordered delivery of SCTP_UNORDERED: This flag requests the un-ordered delivery of
the message. If this flag is clear the datagram is the message. If this flag is clear the datagram is
considered an ordered send. considered an ordered send.
SCTP_ADDR_OVER: This flag, in the one-to-many style, requests SCTP_ADDR_OVER: This flag, in the one-to-many style, requests
the SCTP stack to override the primary destination address the SCTP stack to override the primary destination address
with the address found with the sendto/sendmsg call. with the address found with the sendto/sendmsg call.
SCTP_ABORT: Setting this flag causes the specified association SCTP_ABORT: Setting this flag causes the specified association
to abort by sending an ABORT message to the peer (one-to- to abort by sending an ABORT message to the peer. The ABORT
many style only). The ABORT chunk will contain an error chunk will contain an error cause 'User Initiated Abort'
cause 'User Initiated Abort' with cause code 12. The cause with cause code 12. The cause specific information of this
specific information of this error cause is provided in error cause is provided in msg_iov.
msg_iov.
SCTP_EOF: Setting this flag invokes the SCTP graceful shutdown SCTP_EOF: Setting this flag invokes the SCTP graceful shutdown
procedure on the specified association. Graceful shutdown procedure on the specified association. Graceful shutdown
assures that all data queued by both endpoints is assures that all data queued by both endpoints is
successfully transmitted before closing the association successfully transmitted before closing the association.
(one-to-many style only).
SCTP_SENDALL: This flag, if set, will cause a one-to-many SCTP_SENDALL: This flag, if set, will cause a one-to-many
model socket to send the message to all associations that model socket to send the message to all associations that
are currently established on this socket. For the one-to- are currently established on this socket. For the one-to-
one socket, this flag has no effect. one socket, this flag has no effect.
sinfo_ppid: This value in sendmsg() is an unsigned integer that is sinfo_ppid: This value in sendmsg() is an unsigned integer that is
passed to the remote end in each user message. In recvmsg() this passed to the remote end in each user message. In recvmsg() this
value is the same information that was passed by the upper layer value is the same information that was passed by the upper layer
in the peer application. Please note that the SCTP stack performs in the peer application. Please note that the SCTP stack performs
no byte order modification of this field. For example, if the no byte order modification of this field. For example, if the
DATA chunk has to contain a given value in network byte order, the DATA chunk has to contain a given value in network byte order, the
SCTP user has to perform the htonl() computation. SCTP user has to perform the htonl() computation.
sinfo_context: This value is an opaque 32 bit context datum that is sinfo_context: This value is an opaque 32 bit context datum that is
used in the sendmsg() function. This value is passed back to the used in the sendmsg() function. This value is passed back to the
upper layer if an error occurs on the send of a message and is upper layer if an error occurs on the send of a message and is
retrieved with each undelivered message (Note: if an endpoint has retrieved with each undelivered message.
done multiple sends, all of which fail, multiple different
sinfo_context values will be returned. One with each user data sinfo_timetolive: For the sending side, this field contains the
message). message time to live in milliseconds. The sending side will
sinfo_pr_value: The meaning of this field depends on the PR-SCTP expire the message within the specified time period if the message
policy specified by the sinfo_pr_policy field. It is ignored when as not been sent to the peer within this time period. This value
SCTP_PR_SCTP_NONE is specified. In case of SCTP_PR_SCTP_TTL the will override any default value set using any socket option. Also
lifetime is specified. note that the value of 0 is special in that it indicates no
timeout should occur on this message.
sinfo_tsn: For the receiving side, this field holds a TSN that was sinfo_tsn: For the receiving side, this field holds a TSN that was
assigned to one of the SCTP Data Chunks. For the sending side it assigned to one of the SCTP Data Chunks. For the sending side it
is ignored. is ignored.
sinfo_cumtsn: This field will hold the current cumulative TSN as sinfo_cumtsn: This field will hold the current cumulative TSN as
known by the underlying SCTP layer. Note this field is ignored known by the underlying SCTP layer. Note this field is ignored
when sending. when sending.
sinfo_assoc_id: The association handle field, sinfo_assoc_id, holds sinfo_assoc_id: The association handle field, sinfo_assoc_id, holds
the identifier for the association announced in the SCTP_COMM_UP the identifier for the association announced in the SCTP_COMM_UP
notification. All notifications for a given association have the notification. All notifications for a given association have the
same identifier. Ignored for one-to-one style sockets. same identifier. Ignored for one-to-one style sockets.
An sctp_sndrcvinfo item always corresponds to the data in msg_iov. An sctp_sndrcvinfo item always corresponds to the data in msg_iov.
5.2.3. Extended SCTP Header Information Structure (SCTP_EXTRCV) 5.3.3. Extended SCTP Header Information Structure (SCTP_EXTRCV) -
DEPRECATED
This cmsghdr structure specifies SCTP options for SCTP header This cmsghdr structure specifies SCTP options for SCTP header
information about a received message via recvmsg(). Note that this information about a received message via recvmsg(). Note that this
structure is an extended version of SCTP_SNDRCV (see Section 5.2.2) structure is an extended version of SCTP_SNDRCV (see Section 5.3.2)
and will only be received if the user has set the socket option and will only be received if the user has set the socket option
SCTP_USE_EXT_RCVINFO to true in addition to any event subscription SCTP_USE_EXT_RCVINFO to true in addition to any event subscription
needed to receive ancillary data. See Section 7.1.22 on this socket needed to receive ancillary data. See Section 8.1.22 on this socket
option. Note that next message data is not valid unless the current option. Note that next message data is not valid unless the current
message is completely read, i.e. the MSG_EOR is set, in other words message is completely read, i.e. the MSG_EOR is set, in other words
if the application has more data to read from the current message if the application has more data to read from the current message
then no next message information will be available. then no next message information will be available.
SCTP_NXTINFO described in Section 5.2.6 should be used when possible, SCTP_NXTINFO described in Section 5.3.6 should be used when possible,
since SCTP_EXTRCV is considered deprecated. since SCTP_EXTRCV is considered deprecated.
+--------------+-------------+------------------------+ +--------------+-------------+------------------------+
| cmsg_level | cmsg_type | cmsg_data[] | | cmsg_level | cmsg_type | cmsg_data[] |
+--------------+-------------+------------------------+ +--------------+-------------+------------------------+
| IPPROTO_SCTP | SCTP_EXTRCV | struct sctp_extrcvinfo | | IPPROTO_SCTP | SCTP_EXTRCV | struct sctp_extrcvinfo |
+--------------+-------------+------------------------+ +--------------+-------------+------------------------+
The sctp_extrcvinfo structure is defined below: The sctp_extrcvinfo structure is defined below:
skipping to change at page 29, line 33 skipping to change at page 33, line 47
uint32_t sinfo_tsn; uint32_t sinfo_tsn;
uint32_t sinfo_cumtsn; uint32_t sinfo_cumtsn;
uint16_t serinfo_next_flags; uint16_t serinfo_next_flags;
uint16_t serinfo_next_stream; uint16_t serinfo_next_stream;
uint32_t serinfo_next_aid; uint32_t serinfo_next_aid;
uint32_t serinfo_next_length; uint32_t serinfo_next_length;
uint32_t serinfo_next_ppid; uint32_t serinfo_next_ppid;
sctp_assoc_t sinfo_assoc_id; sctp_assoc_t sinfo_assoc_id;
}; };
sinfo_*: Please see Section 5.2.2 for the details for these fields. sinfo_*: Please see Section 5.3.2 for the details for these fields.
serinfo_next_flags: This bitmask will hold one or more of the serinfo_next_flags: This bitmask will hold one or more of the
following values: following values:
SCTP_NEXT_MSG_AVAIL: This bit, when set to 1, indicates that next SCTP_NEXT_MSG_AVAIL: This bit, when set to 1, indicates that next
message information is available i.e.: next_stream, message information is available i.e.: next_stream,
next_asocid, next_length and next_ppid fields all have valid next_asocid, next_length and next_ppid fields all have valid
values. If this bit is set to 0, then these fields are not values. If this bit is set to 0, then these fields are not
valid and should be ignored. valid and should be ignored.
SCTP_NEXT_MSG_ISCOMPLETE: This bit, when set, indicates that the SCTP_NEXT_MSG_ISCOMPLETE: This bit, when set, indicates that the
next message is completely in the receive buffer. The next message is completely in the receive buffer. The
next_length field thus contains the entire message size. If next_length field thus contains the entire message size. If
this flag is set to 0, then the next_length field only contains this flag is set to 0, then the next_length field only contains
part of the message size since the message is still being part of the message size since the message is still being
received (it is being partially delivered). received (it is being partially delivered).
SCTP_NEXT_MSG_IS_UNORDERED: This bit, when set, indicates that SCTP_NEXT_MSG_IS_UNORDERED: This bit, when set, indicates that
the next message to be received was sent by the peer as the next message to be received was sent by the peer as
unordered. If this bit is not set (i.e the bit is 0) the next unordered. If this bit is not set (i.e. the bit is 0) the next
message to be read is an ordered message in the stream message to be read is an ordered message in the stream
specified. specified.
SCTP_NEXT_MSG_IS_NOTIFICATION: This bit, when set, indicates that SCTP_NEXT_MSG_IS_NOTIFICATION: This bit, when set, indicates that
the next message to be received is not a message from the peer, the next message to be received is not a message from the peer,
but instead is a MSG_NOTIFICATION from the local SCTP stack. but instead is a MSG_NOTIFICATION from the local SCTP stack.
serinfo_next_stream: This value, when valid (see serinfo_next_stream: This value, when valid (see
serinfo_next_flags), contains the next stream number that will be serinfo_next_flags), contains the next stream number that will be
received on a subsequent call to one of the receive message received on a subsequent call to one of the receive message
functions. functions.
serinfo_next_aid: This value, when valid (see serinfo_next_flags), serinfo_next_aid: This value, when valid (see serinfo_next_flags),
contains the next association identification that will be received contains the next association identification that will be received
on a subsequent call to one of the receive message functions. on a subsequent call to one of the receive message functions.
serinfo_next_length: This value, when valid (see serinfo_next_length: This value, when valid (see
serinfo_next_flags), contains the length of the next message that serinfo_next_flags), contains the length of the next message that
will be received on a subsequent call to one of the receive will be received on a subsequent call to one of the receive
message functions. Note that this length may be a partial length message functions. Note that this length may be a partial length
depending on the settings of next_flags. depending on the settings of next_flags.
serinfo_next_ppid: This value, when valid (see serinfo_next_flags), serinfo_next_ppid: This value, when valid (see serinfo_next_flags),
contains the ppid of the next message that will be received on a contains the ppid of the next message that will be received on a
subsequent call to one of the receive message functions. subsequent call to one of the receive message functions.
5.2.4. SCTP Send Information Structure (SCTP_SNDINFO) 5.3.4. SCTP Send Information Structure (SCTP_SNDINFO)
This cmsghdr structure specifies SCTP options for sendmsg(). This cmsghdr structure specifies SCTP options for sendmsg().
+--------------+--------------+---------------------+ +--------------+--------------+---------------------+
| cmsg_level | cmsg_type | cmsg_data[] | | cmsg_level | cmsg_type | cmsg_data[] |
+--------------+--------------+---------------------+ +--------------+--------------+---------------------+
| IPPROTO_SCTP | SCTP_SNDINFO | struct sctp_sndinfo | | IPPROTO_SCTP | SCTP_SNDINFO | struct sctp_sndinfo |
+--------------+--------------+---------------------+ +--------------+--------------+---------------------+
The sctp_sndinfo structure is defined below: The sctp_sndinfo structure is defined below:
skipping to change at page 30, line 47 skipping to change at page 35, line 24
uint16_t snd_sid; uint16_t snd_sid;
uint16_t snd_flags; uint16_t snd_flags;
uint32_t snd_ppid; uint32_t snd_ppid;
uint32_t snd_context; uint32_t snd_context;
sctp_assoc_t snd_assoc_id; sctp_assoc_t snd_assoc_id;
}; };
snd_sid: This value holds the stream number that the application snd_sid: This value holds the stream number that the application
wishes to send this message to. If a sender specifies an invalid wishes to send this message to. If a sender specifies an invalid
stream number an error indication is returned and the call fails. stream number an error indication is returned and the call fails.
snd_flags: This field may contain any of the following flags and is snd_flags: This field may contain any of the following flags and is
composed of a bitwise OR of these values. composed of a bitwise OR of these values.
SCTP_UNORDERED: This flag requests the un-ordered delivery of the SCTP_UNORDERED: This flag requests the un-ordered delivery of the
message. If this flag is clear the datagram is considered an message. If this flag is clear the datagram is considered an
ordered send. ordered send.
SCTP_ADDR_OVER: This flag, in the one-to-many style, requests the SCTP_ADDR_OVER: This flag, in the one-to-many style, requests the
SCTP stack to override the primary destination address with the SCTP stack to override the primary destination address with the
address found with the sendto()/sendmsg call. address found with the sendto()/sendmsg call.
SCTP_ABORT: Setting this flag causes the specified association to SCTP_ABORT: Setting this flag causes the specified association to
abort by sending an ABORT message to the peer (one-to-many abort by sending an ABORT message to the peer. The ABORT chunk
style only). The ABORT chunk will contain an error cause 'User will contain an error cause 'User Initiated Abort' with cause
Initiated Abort' with cause code 12. The cause specific code 12. The cause specific information of this error cause is
information of this error cause is provided in msg_iov. provided in msg_iov.
SCTP_EOF: Setting this flag invokes the SCTP graceful shutdown SCTP_EOF: Setting this flag invokes the SCTP graceful shutdown
procedures on the specified association. Graceful shutdown procedures on the specified association. Graceful shutdown
assures that all data queued by both endpoints is successfully assures that all data queued by both endpoints is successfully
transmitted before closing the association (one-to-many style transmitted before closing the association.
only).
SCTP_SENDALL: This flag, if set, will cause a one-to-many model SCTP_SENDALL: This flag, if set, will cause a one-to-many model
socket to send the message to all associations that are socket to send the message to all associations that are
currently established on this socket. For the one-to-one currently established on this socket. For the one-to-one
socket, this flag has no effect. socket, this flag has no effect.
snd_ppid: This value in sendmsg() is an unsigned integer that is snd_ppid: This value in sendmsg() is an unsigned integer that is
passed to the remote end in each user message. Please note that passed to the remote end in each user message. Please note that
the SCTP stack performs no byte order modification of this field. the SCTP stack performs no byte order modification of this field.
For example, if the DATA chunk has to contain a given value in For example, if the DATA chunk has to contain a given value in
network byte order, the SCTP user has to perform the htonl() network byte order, the SCTP user has to perform the htonl()
computation. computation.
snd_context: This value is an opaque 32 bit context datum that is snd_context: This value is an opaque 32 bit context datum that is
used in the sendmsg() function. This value is passed back to the used in the sendmsg() function. This value is passed back to the
upper layer if an error occurs on the send of a message and is upper layer if an error occurs on the send of a message and is
retrieved with each undelivered message (Note: if an endpoint has retrieved with each undelivered message.
done multiple sends, all of which fail, multiple different
sinfo_context values will be returned. One with each user data
message).
snd_assoc_id: The association handle field, sinfo_assoc_id, holds snd_assoc_id: The association handle field, sinfo_assoc_id, holds
the identifier for the association announced in the SCTP_COMM_UP the identifier for the association announced in the SCTP_COMM_UP
notification. All notifications for a given association have the notification. All notifications for a given association have the
same identifier. Ignored for one-to-one style sockets. same identifier. Ignored for one-to-one style sockets.
An sctp_sndinfo item always corresponds to the data in msg_iov. An sctp_sndinfo item always corresponds to the data in msg_iov.
5.2.5. SCTP Receive Information Structure (SCTP_RCVINFO) 5.3.5. SCTP Receive Information Structure (SCTP_RCVINFO)
This cmsghdr structure describes SCTP receive information about a This cmsghdr structure describes SCTP receive information about a
received message through recvmsg(). received message through recvmsg().
To enable the delivery of this information an application must use To enable the delivery of this information an application must use
the SCTP_RECVRCVINFO socket option (see Section 7.1.29). the SCTP_RECVRCVINFO socket option (see Section 8.1.29).
+--------------+--------------+---------------------+ +--------------+--------------+---------------------+
| cmsg_level | cmsg_type | cmsg_data[] | | cmsg_level | cmsg_type | cmsg_data[] |
+--------------+--------------+---------------------+ +--------------+--------------+---------------------+
| IPPROTO_SCTP | SCTP_RCVINFO | struct sctp_rcvinfo | | IPPROTO_SCTP | SCTP_RCVINFO | struct sctp_rcvinfo |
+--------------+--------------+---------------------+ +--------------+--------------+---------------------+
The sctp_rcvinfo structure is defined below: The sctp_rcvinfo structure is defined below:
struct sctp_rcvinfo { struct sctp_rcvinfo {
uint16_t rcv_sid; uint16_t rcv_sid;
uint16_t rcv_ssn; uint16_t rcv_ssn;
uint16_t rcv_flags; uint16_t rcv_flags;
uint32_t rcv_ppid; uint32_t rcv_ppid;
uint32_t rcv_tsn; uint32_t rcv_tsn;
uint32_t rcv_cumtsn; uint32_t rcv_cumtsn;
uint32_t rcv_context;
sctp_assoc_t rcv_assoc_id; sctp_assoc_t rcv_assoc_id;
}; };
rcv_sid: The SCTP stack places the message's stream number in this rcv_sid: The SCTP stack places the message's stream number in this
value. value.
rcv_ssn: This value contains the stream sequence number that the rcv_ssn: This value contains the stream sequence number that the
remote endpoint placed in the DATA chunk. For fragmented messages remote endpoint placed in the DATA chunk. For fragmented messages
this is the same number for all deliveries of the message (if more this is the same number for all deliveries of the message (if more
than one recvmsg() is needed to read the message). than one recvmsg() is needed to read the message).
rcv_flags: This field may contain any of the following flags and is rcv_flags: This field may contain any of the following flags and is
composed of a bitwise OR of these values. composed of a bitwise OR of these values.
SCTP_UNORDERED: This flag is present when the message was sent SCTP_UNORDERED: This flag is present when the message was sent
un-ordered. un-ordered.
rcv_ppid: This value is the same information that was passed by the rcv_ppid: This value is the same information that was passed by the
upper layer in the peer application. Please note that the SCTP upper layer in the peer application. Please note that the SCTP
stack performs no byte order modification of this field. For stack performs no byte order modification of this field. For
example, if the DATA chunk has to contain a given value in network example, if the DATA chunk has to contain a given value in network
byte order, the SCTP user has to perform the htonl() computation. byte order, the SCTP user has to perform the ntohl() computation.
rcv_tsn: This field holds a TSN that was assigned to one of the SCTP rcv_tsn: This field holds a TSN that was assigned to one of the SCTP
Data Chunks. Data Chunks.
rcv_cumtsn: This field will hold the current cumulative TSN as known rcv_cumtsn: This field will hold the current cumulative TSN as known
by the underlying SCTP layer. by the underlying SCTP layer.
rcv_assoc_id: The association handle field, sinfo_assoc_id, holds rcv_assoc_id: The association handle field, sinfo_assoc_id, holds
the identifier for the association announced in the SCTP_COMM_UP the identifier for the association announced in the SCTP_COMM_UP
notification. All notifications for a given association have the notification. All notifications for a given association have the
same identifier. Ignored for one-to-one style sockets. same identifier. Ignored for one-to-one style sockets.
rcv_context: This value is an opaque 32 bit context datum that was
set by the user with the SCTP_CONTEXT socket option. This value
is passed back to the upper layer if an error occurs on the send
of a message and is retrieved with each undelivered message.
An sctp_rcvinfo item always corresponds to the data in msg_iov. An sctp_rcvinfo item always corresponds to the data in msg_iov.
5.2.6. SCTP Next Receive Information Structure (SCTP_NXTINFO) 5.3.6. SCTP Next Receive Information Structure (SCTP_NXTINFO)
This cmsghdr structure describes SCTP receive information of the next This cmsghdr structure describes SCTP receive information of the next
message which will be delivered through recvmsg() if this information message which will be delivered through recvmsg() if this information
is already available when delivering the current message. is already available when delivering the current message.
It uses the same structure as the SCTP Receive Information Structure.
To enable the delivery of this information an application must use To enable the delivery of this information an application must use
the SCTP_RECVNXTINFO socket option (see Section 7.1.30). the SCTP_RECVNXTINFO socket option (see Section 8.1.30).
+--------------+--------------+---------------------+ +--------------+--------------+---------------------+
| cmsg_level | cmsg_type | cmsg_data[] | | cmsg_level | cmsg_type | cmsg_data[] |
+--------------+--------------+---------------------+ +--------------+--------------+---------------------+
| IPPROTO_SCTP | SCTP_NXTINFO | struct sctp_rcvinfo | | IPPROTO_SCTP | SCTP_NXTINFO | struct sctp_nxtinfo |
+--------------+--------------+---------------------+ +--------------+--------------+---------------------+
5.2.7. SCTP PR-SCTP Information Structure (SCTP_PRINFO) The sctp_nxtinfo structure is defined below:
struct sctp_nxtinfo {
uint16_t nxt_sid;
uint16_t nxt_flags;
uint32_t nxt_ppid;
size_t nxt_length;
sctp_assoc_t nxt_assoc_id;
};
nxt_sid: The SCTP stack places the next message's stream number in
this value.
nxt_flags: This field may contain any of the following flags and is
composed of a bitwise OR of these values.
SCTP_UNORDERED: This flag is present when the next message was
sent un-ordered.
SCTP_COMPLETE: This flag indicates that the entire message has
been received and is in the socket buffer. Note that this has
special implications with respect to the nxt_length field, see
nxt_length description below.
SCTP_NOTIFICATION: This flag is present when the next message is
not a user message but instead is a notification.
nxt_ppid: This value is the same information that was passed by the
upper layer in the peer application for the next message. Please
note that the SCTP stack performs no byte order modification of
this field. For example, if the DATA chunk has to contain a given
value in network byte order, the SCTP user has to perform the
ntohl() computation.
nxt_length: This value is the length of the message currently within
the socket buffer. This might NOT be the entire length of the
message since a partial delivery may be in progress. Only if the
flag SCTP_COMPLETE is set in the nxt_flags field does this field
represent the entire next message size.
nxt_assoc_id: The association handle field of the next message,
nxt_assoc_id, holds the identifier for the association announced
in the SCTP_COMM_UP notification. All notifications for a given
association have the same identifier. Ignored for one-to-one
style sockets.
5.3.7. SCTP PR-SCTP Information Structure (SCTP_PRINFO)
This cmsghdr structure specifies SCTP options for sendmsg(). This cmsghdr structure specifies SCTP options for sendmsg().
+--------------+-------------+--------------------+ +--------------+-------------+--------------------+
| cmsg_level | cmsg_type | cmsg_data[] | | cmsg_level | cmsg_type | cmsg_data[] |
+--------------+-------------+--------------------+ +--------------+-------------+--------------------+
| IPPROTO_SCTP | SCTP_PRINFO | struct sctp_prinfo | | IPPROTO_SCTP | SCTP_PRINFO | struct sctp_prinfo |
+--------------+-------------+--------------------+ +--------------+-------------+--------------------+
The sctp_prinfo structure is defined below: The sctp_prinfo structure is defined below:
skipping to change at page 33, line 44 skipping to change at page 39, line 33
struct sctp_prinfo { struct sctp_prinfo {
uint16_t pr_policy; uint16_t pr_policy;
uint32_t pr_value; uint32_t pr_value;
}; };
pr_policy: This specifies which PR-SCTP policy is used. Using pr_policy: This specifies which PR-SCTP policy is used. Using
SCTP_PR_SCTP_NONE results in a reliable transmission. When SCTP_PR_SCTP_NONE results in a reliable transmission. When
SCTP_PR_SCTP_TTL is used, the PR-SCTP policy "timed reliability" SCTP_PR_SCTP_TTL is used, the PR-SCTP policy "timed reliability"
defined in [RFC3758] is used. In this case, the lifetime is defined in [RFC3758] is used. In this case, the lifetime is
provided in pr_value. provided in pr_value.
pr_value: The meaning of this field depends on the PR-SCTP policy pr_value: The meaning of this field depends on the PR-SCTP policy
specified by the pr_policy field. It is ignored when specified by the pr_policy field. It is ignored when
SCTP_PR_SCTP_NONE is specified. In case of SCTP_PR_SCTP_TTL the SCTP_PR_SCTP_NONE is specified. In case of SCTP_PR_SCTP_TTL the
lifetime in milliseconds is specified. lifetime in milliseconds is specified.
An sctp_prinfo item always corresponds to the data in msg_iov. An sctp_prinfo item always corresponds to the data in msg_iov.
5.2.8. SCTP AUTH Information Structure (SCTP_AUTHINFO) 5.3.8. SCTP AUTH Information Structure (SCTP_AUTHINFO)
This cmsghdr structure specifies SCTP options for sendmsg(). This cmsghdr structure specifies SCTP options for sendmsg().
+--------------+---------------+----------------------+ +--------------+---------------+----------------------+
| cmsg_level | cmsg_type | cmsg_data[] | | cmsg_level | cmsg_type | cmsg_data[] |
+--------------+---------------+----------------------+ +--------------+---------------+----------------------+
| IPPROTO_SCTP | SCTP_AUTHINFO | struct sctp_authinfo | | IPPROTO_SCTP | SCTP_AUTHINFO | struct sctp_authinfo |
+--------------+---------------+----------------------+ +--------------+---------------+----------------------+
The sctp_authinfo structure is defined below: The sctp_authinfo structure is defined below:
skipping to change at page 34, line 29 skipping to change at page 40, line 17
}; };
auth_keyid: This specifies the shared key identifier used for auth_keyid: This specifies the shared key identifier used for
sending the user message. sending the user message.
An sctp_authinfo item always corresponds to the data in msg_iov. An sctp_authinfo item always corresponds to the data in msg_iov.
Please note that the SCTP implementation must not bundle user Please note that the SCTP implementation must not bundle user
messages that needs to be authenticated using different shared key messages that needs to be authenticated using different shared key
identifiers. identifiers.
5.2.9. SCTP Destination Address Structure (IPv4) (SCTP_DSTADDRV4) 5.3.9. SCTP Destination Address Structure (IPv4) (SCTP_DSTADDRV4)
This cmsghdr structure specifies SCTP options for sendmsg(). This cmsghdr structure specifies SCTP options for sendmsg().
+--------------+----------------+----------------+ +--------------+----------------+----------------+
| cmsg_level | cmsg_type | cmsg_data[] | | cmsg_level | cmsg_type | cmsg_data[] |
+--------------+----------------+----------------+ +--------------+----------------+----------------+
| IPPROTO_SCTP | SCTP_DSTADDRV4 | struct in_addr | | IPPROTO_SCTP | SCTP_DSTADDRV4 | struct in_addr |
+--------------+----------------+----------------+ +--------------+----------------+----------------+
This ancillary data can be used to provide more than one destination This ancillary data can be used to provide more than one destination
address to sendmsg(). It can be used to implement sctp_sendv() using address to sendmsg(). It can be used to implement sctp_sendv() using
send_msg(). send_msg().
5.2.10. SCTP Destination Address Structure (IPv6) (SCTP_DSTADDRV6) 5.3.10. SCTP Destination Address Structure (IPv6) (SCTP_DSTADDRV6)
This cmsghdr structure specifies SCTP options for sendmsg(). This cmsghdr structure specifies SCTP options for sendmsg().
+--------------+----------------+-----------------+ +--------------+----------------+-----------------+
| cmsg_level | cmsg_type | cmsg_data[] | | cmsg_level | cmsg_type | cmsg_data[] |
+--------------+----------------+-----------------+ +--------------+----------------+-----------------+
| IPPROTO_SCTP | SCTP_DSTADDRV6 | struct in6_addr | | IPPROTO_SCTP | SCTP_DSTADDRV6 | struct in6_addr |
+--------------+----------------+-----------------+ +--------------+----------------+-----------------+
This ancillary data can be used to provide more than one destination This ancillary data can be used to provide more than one destination
address to sendmsg(). It can be used to implement sctp_sendv() using address to sendmsg(). It can be used to implement sctp_sendv() using
send_msg(). send_msg().
5.3. SCTP Events and Notifications 6. SCTP Events and Notifications
An SCTP application may need to understand and process events and An SCTP application may need to understand and process events and
errors that happen on the SCTP stack. These events include network errors that happen on the SCTP stack. These events include network
status changes, association startups, remote operational errors and status changes, association startups, remote operational errors and
undeliverable messages. All of these can be essential for the undeliverable messages. All of these can be essential for the
application. application.
When an SCTP application layer does a recvmsg() the message read is When an SCTP application layer does a recvmsg() the message read is
normally a data message from a peer endpoint. If the application normally a data message from a peer endpoint. If the application
wishes to have the SCTP stack deliver notifications of non-data wishes to have the SCTP stack deliver notifications of non-data
events, it sets the appropriate socket option for the notifications events, it sets the appropriate socket option for the notifications
it wants. See Section 7.4 for these socket options. When a it wants. See Section 6.2 for these socket options. When a
notification arrives, recvmsg() returns the notification in the notification arrives, recvmsg() returns the notification in the
application-supplied data buffer via msg_iov, and sets application-supplied data buffer via msg_iov, and sets
MSG_NOTIFICATION in msg_flags. MSG_NOTIFICATION in msg_flags.
This section details the notification structures. Every notification This section details the notification structures. Every notification
structure carries some common fields which provide general structure carries some common fields which provide general
information. information.
A recvmsg() call will return only one notification at a time. Just A recvmsg() call will return only one notification at a time. Just
as when reading normal data, it may return part of a notification if as when reading normal data, it may return part of a notification if
the msg_iov buffer is not large enough. If a single read is not the msg_iov buffer is not large enough. If a single read is not
sufficient, msg_flags will have MSG_EOR clear. The user must finish sufficient, msg_flags will have MSG_EOR clear. The user must finish
reading the notification before subsequent data can arrive. reading the notification before subsequent data can arrive.
5.3.1. SCTP Notification Structure 6.1. SCTP Notification Structure
The notification structure is defined as the union of all The notification structure is defined as the union of all
notification types. notification types.
union sctp_notification { union sctp_notification {
struct sctp_tlv { struct sctp_tlv {
uint16_t sn_type; /* Notification type. */ uint16_t sn_type; /* Notification type. */
uint16_t sn_flags; uint16_t sn_flags;
uint32_t sn_length; uint32_t sn_length;
} sn_header; } sn_header;
struct sctp_assoc_change sn_assoc_change; struct sctp_assoc_change sn_assoc_change;
struct sctp_paddr_change sn_paddr_change; struct sctp_paddr_change sn_paddr_change;
struct sctp_remote_error sn_remote_error; struct sctp_remote_error sn_remote_error;
struct sctp_send_failed sn_send_failed; struct sctp_send_failed sn_send_failed;
struct sctp_shutdown_event sn_shutdown_event; struct sctp_shutdown_event sn_shutdown_event;
struct sctp_adaptation_event sn_adaptation_event; struct sctp_adaptation_event sn_adaptation_event;
struct sctp_pdapi_event sn_pdapi_event; struct sctp_pdapi_event sn_pdapi_event;
struct sctp_authkey_event sn_auth_event; struct sctp_authkey_event sn_auth_event;
struct sctp_sender_dry_event sn_sender_dry_event; struct sctp_sender_dry_event sn_sender_dry_event;
struct sctp_send_failed_event sn_send_failed_event;
}; };
sn_type: The following list describes the SCTP notification and sn_type: The following list describes the SCTP notification and
event types for the field sn_type. event types for the field sn_type.
SCTP_ASSOC_CHANGE: This tag indicates that an association has SCTP_ASSOC_CHANGE: This tag indicates that an association has
either been opened or closed. Refer to Section 5.3.2 for either been opened or closed. Refer to Section 6.1.1 for
details. details.
SCTP_PEER_ADDR_CHANGE: This tag indicates that an address that is SCTP_PEER_ADDR_CHANGE: This tag indicates that an address that is
part of an existing association has experienced a change of part of an existing association has experienced a change of
state (e.g. a failure or return to service of the reachability state (e.g. a failure or return to service of the reachability
of an endpoint via a specific transport address). Please see of an endpoint via a specific transport address). Please see
Section 5.3.3 for data structure details. Section 6.1.2 for data structure details.
SCTP_REMOTE_ERROR: The attached error message is an Operational SCTP_REMOTE_ERROR: The attached error message is an Operational
Error received from the remote peer. It includes the complete Error received from the remote peer. It includes the complete
TLV sent by the remote endpoint. See Section 5.3.4 for the TLV sent by the remote endpoint. See Section 6.1.3 for the
detailed format. detailed format.
SCTP_SEND_FAILED: The attached datagram could not be sent to the
remote endpoint. This structure includes the original SCTP_SEND_FAILED_EVENT: The attached datagram could not be sent
SCTP_SNDRCVINFO that was used in sending this message i.e. this to the remote endpoint. This structure includes the original
structure uses the sctp_sndrcvinfo per Section 5.3.5. SCTP_SNDINFO that was used in sending this message i.e. this
structure uses the sctp_sndinfo per Section 6.1.11.
SCTP_SHUTDOWN_EVENT: The peer has sent a SHUTDOWN. No further SCTP_SHUTDOWN_EVENT: The peer has sent a SHUTDOWN. No further
data should be sent on this socket. data should be sent on this socket.
SCTP_ADAPTATION_INDICATION: This notification holds the peer's SCTP_ADAPTATION_INDICATION: This notification holds the peer's
indicated adaptation layer. Please see Section 5.3.7. indicated adaptation layer. Please see Section 6.1.6.
SCTP_PARTIAL_DELIVERY_EVENT: This notification is used to tell a SCTP_PARTIAL_DELIVERY_EVENT: This notification is used to tell a
receiver that the partial delivery has been aborted. This may receiver that the partial delivery has been aborted. This may
indicate the association is about to be aborted. Please see indicate the association is about to be aborted. Please see
Section 5.3.8. Section 6.1.7.
SCTP_AUTHENTICATION_EVENT: This notification is used to tell a SCTP_AUTHENTICATION_EVENT: This notification is used to tell a
receiver that either an error occurred on authentication, or a receiver that either an error occurred on authentication, or a
new key was made active. See Section 5.3.9. new key was made active. See Section 6.1.8.
SCTP_SENDER_DRY_EVENT: This notification is used to inform the SCTP_SENDER_DRY_EVENT: This notification is used to inform the
application that the sender has no user data queued anymore, application that the sender has no more user data queued for
neither for transmission nor retransmission. See transmission nor retransmission. See Section 6.1.9.
Section 5.3.10.
sn_flags: These are notification-specific flags. sn_flags: These are notification-specific flags.
sn_length: This is the length of the whole sctp_notification sn_length: This is the length of the whole sctp_notification
structure including the sn_type, sn_flags, and sn_length fields. structure including the sn_type, sn_flags, and sn_length fields.
5.3.2. SCTP_ASSOC_CHANGE 6.1.1. SCTP_ASSOC_CHANGE
Communication notifications inform the ULP that an SCTP association Communication notifications inform the application that an SCTP
has either begun or ended. The identifier for a new association is association has either begun or ended. The identifier for a new
provided by this notification. The notification information has the association is provided by this notification. The notification
following format: information has the following format:
struct sctp_assoc_change { struct sctp_assoc_change {
uint16_t sac_type; uint16_t sac_type;
uint16_t sac_flags; uint16_t sac_flags;
uint32_t sac_length; uint32_t sac_length;
uint16_t sac_state; uint16_t sac_state;
uint16_t sac_error; uint16_t sac_error;
uint16_t sac_outbound_streams; uint16_t sac_outbound_streams;
uint16_t sac_inbound_streams; uint16_t sac_inbound_streams;
sctp_assoc_t sac_assoc_id; sctp_assoc_t sac_assoc_id;
skipping to change at page 37, line 33 skipping to change at page 43, line 25
uint32_t sac_length; uint32_t sac_length;
uint16_t sac_state; uint16_t sac_state;
uint16_t sac_error; uint16_t sac_error;
uint16_t sac_outbound_streams; uint16_t sac_outbound_streams;
uint16_t sac_inbound_streams; uint16_t sac_inbound_streams;
sctp_assoc_t sac_assoc_id; sctp_assoc_t sac_assoc_id;
uint8_t sac_info[]; uint8_t sac_info[];
}; };
sac_type: It should be SCTP_ASSOC_CHANGE. sac_type: It should be SCTP_ASSOC_CHANGE.
sac_flags: Currently unused. sac_flags: Currently unused.
sac_length: This field is the total length of the notification data, sac_length: This field is the total length of the notification data,
including the notification header. including the notification header.
sac_state: This field holds one of a number of values that sac_state: This field holds one of a number of values that
communicate the event that happened to the association. They communicate the event that happened to the association. They
include: include:
SCTP_COMM_UP: A new association is now ready and data may be SCTP_COMM_UP: A new association is now ready and data may be
exchanged with this peer. When an association has been exchanged with this peer. When an association has been
established successfully, this notification should be the first established successfully, this notification should be the first
one. one.
SCTP_COMM_LOST: The association has failed. The association is SCTP_COMM_LOST: The association has failed. The association is
now in the closed state. If SEND_FAILED notifications are now in the closed state. If SEND_FAILED notifications are
turned on, an SCTP_COMM_LOST is accompanied by a series of turned on, an SCTP_COMM_LOST is accompanied by a series of
SCTP_SEND_FAILED_EVENT events, one for each outstanding SCTP_SEND_FAILED_EVENT events, one for each outstanding
message. message.
SCTP_RESTART: SCTP has detected that the peer has restarted. SCTP_RESTART: SCTP has detected that the peer has restarted.
SCTP_SHUTDOWN_COMP: The association has gracefully closed. SCTP_SHUTDOWN_COMP: The association has gracefully closed.
SCTP_CANT_STR_ASSOC: The association failed to setup. If non SCTP_CANT_STR_ASSOC: The association failed to setup. If non
blocking mode is set and data was sent (on a one-to-many style blocking mode is set and data was sent (on a one-to-many style
socket), an SCTP_CANT_STR_ASSOC is accompanied by a series of socket), an SCTP_CANT_STR_ASSOC is accompanied by a series of
SCTP_SEND_FAILED_EVENT events, one for each outstanding SCTP_SEND_FAILED_EVENT events, one for each outstanding
message. message.
sac_error: If the state was reached due to an error condition (e.g. sac_error: If the state was reached due to an error condition (e.g.
SCTP_COMM_LOST) any relevant error information is available in SCTP_COMM_LOST) any relevant error information is available in
this field. This corresponds to the protocol error codes defined this field. This corresponds to the protocol error codes defined
in [RFC4960]. in [RFC4960].
sac_outbound_streams: sac_outbound_streams:
sac_inbound_streams: The maximum number of streams allowed in each sac_inbound_streams: The maximum number of streams allowed in each
direction are available in sac_outbound_streams and sac_inbound direction are available in sac_outbound_streams and sac_inbound
streams. streams.
sac_assoc_id: The association id field holds the identifier for the sac_assoc_id: The association id field holds the identifier for the
association. All notifications for a given association have the association. All notifications for a given association have the
same association identifier. For a one-to-one style socket, this same association identifier. For a one-to-one style socket, this
field is ignored. field is ignored.
sac_info: If the sac_state is SCTP_COMM_LOST and an ABORT chunk was sac_info: If the sac_state is SCTP_COMM_LOST and an ABORT chunk was
received for this association, sac_info[] contains the complete received for this association, sac_info[] contains the complete
ABORT chunk as defined in the SCTP specification [RFC4960] Section ABORT chunk as defined in the SCTP specification [RFC4960] Section
3.3.7. If the sac_state is SCTP_COMM_UP or SCTP_RESTART, sac_info 3.3.7. If the sac_state is SCTP_COMM_UP or SCTP_RESTART, sac_info
may contain an array of uint8_t describing the features that the may contain an array of uint8_t describing the features that the
current association supports. Features may include current association supports. Features may include
SCTP_ASSOC_SUPPORTS_PR: Both endpoints support the protocol SCTP_ASSOC_SUPPORTS_PR: Both endpoints support the protocol
extension described in [RFC3758]. extension described in [RFC3758].
SCTP_ASSOC_SUPPORTS_AUTH: Both endpoints support the protocol SCTP_ASSOC_SUPPORTS_AUTH: Both endpoints support the protocol
extension described in [RFC4895]. extension described in [RFC4895].
SCTP_ASSOC_SUPPORTS_ASCONF: Both endpoints support the protocol SCTP_ASSOC_SUPPORTS_ASCONF: Both endpoints support the protocol
extension described in [RFC5061]. extension described in [RFC5061].
SCTP_ASSOC_SUPPORTS_MULTIBUF: For a one-to-many style socket, the SCTP_ASSOC_SUPPORTS_MULTIBUF: For a one-to-many style socket, the
local endpoints use separate send and/or receive buffers for local endpoints use separate send and/or receive buffers for
each SCTP association. each SCTP association.
5.3.3. SCTP_PEER_ADDR_CHANGE 6.1.2. SCTP_PEER_ADDR_CHANGE
When a destination address of a multi-homed peer encounters a state When a destination address of a multi-homed peer encounters a state
change a peer address change event is sent. The notification has the change a peer address change event is sent. The notification has the
following format: following format:
struct sctp_paddr_change { struct sctp_paddr_change {
uint16_t spc_type; uint16_t spc_type;
uint16_t spc_flags; uint16_t spc_flags;
uint32_t spc_length; uint32_t spc_length;
struct sockaddr_storage spc_aaddr; struct sockaddr_storage spc_aaddr;
skipping to change at page 39, line 4 skipping to change at page 45, line 13
following format: following format:
struct sctp_paddr_change { struct sctp_paddr_change {
uint16_t spc_type; uint16_t spc_type;
uint16_t spc_flags; uint16_t spc_flags;
uint32_t spc_length; uint32_t spc_length;
struct sockaddr_storage spc_aaddr; struct sockaddr_storage spc_aaddr;
uint32_t spc_state; uint32_t spc_state;
uint32_t spc_error; uint32_t spc_error;
sctp_assoc_t spc_assoc_id; sctp_assoc_t spc_assoc_id;
} }
spc_type: It should be SCTP_PEER_ADDR_CHANGE. spc_type: It should be SCTP_PEER_ADDR_CHANGE.
spc_flags: Currently unused. spc_flags: Currently unused.
spc_length: This field is the total length of the notification data, spc_length: This field is the total length of the notification data,
including the notification header. including the notification header.
spc_aaddr: The affected address field holds the remote peer's spc_aaddr: The affected address field holds the remote peer's
address that is encountering the change of state. address that is encountering the change of state.
spc_state: This field holds one of a number of values that spc_state: This field holds one of a number of values that
communicate the event that happened to the address. They include: communicate the event that happened to the address. They include:
SCTP_ADDR_AVAILABLE: This address is now reachable. This SCTP_ADDR_AVAILABLE: This address is now reachable. This
notification is provided whenever an address becomes reachable notification is provided whenever an address becomes reachable.
and was unreachable.
SCTP_ADDR_UNREACHABLE: The address specified can no longer be SCTP_ADDR_UNREACHABLE: The address specified can no longer be
reached. Any data sent to this address is rerouted to an reached. Any data sent to this address is rerouted to an
alternate until this address becomes reachable. This alternate until this address becomes reachable. This
notification is provided whenever an address becomes notification is provided whenever an address becomes
unreachable and was reachable. unreachable.
SCTP_ADDR_REMOVED: The address is no longer part of the SCTP_ADDR_REMOVED: The address is no longer part of the
association. association.
SCTP_ADDR_ADDED: The address is now part of the association. SCTP_ADDR_ADDED: The address is now part of the association.
SCTP_ADDR_MADE_PRIM: This address has now been made to be the SCTP_ADDR_MADE_PRIM: This address has now been made to be the
primary destination address. primary destination address. This notification is provided
SCTP_ADDR_CONFIRMED: This address has now been confirmed as a whenever an address is made primary.
valid address. This notification is provided once for each
address as soon as the address is confirmed.
spc_error: If the state was reached due to any error condition (e.g. spc_error: If the state was reached due to any error condition (e.g.
SCTP_ADDR_UNREACHABLE) any relevant error information is available SCTP_ADDR_UNREACHABLE) any relevant error information is available
in this field. in this field.
spc_assoc_id: The association id field holds the identifier for the spc_assoc_id: The association id field holds the identifier for the
association. All notifications for a given association have the association. All notifications for a given association have the
same association identifier. For a one-to-one style socket, this same association identifier. For a one-to-one style socket, this
field is ignored. field is ignored.
5.3.4. SCTP_REMOTE_ERROR 6.1.3. SCTP_REMOTE_ERROR
A remote peer may send an Operational Error message to its peer. A remote peer may send an Operational Error message to its peer.
This message indicates a variety of error conditions on an This message indicates a variety of error conditions on an
association. The entire ERROR chunk as it appears on the wire is association. The entire ERROR chunk as it appears on the wire is
included in an SCTP_REMOTE_ERROR event. Please refer to the SCTP included in an SCTP_REMOTE_ERROR event. Please refer to the SCTP
specification [RFC4960] and any extensions for a list of possible specification [RFC4960] and any extensions for a list of possible
error formats. An SCTP error notification has the following format: error formats. An SCTP error notification has the following format:
struct sctp_remote_error { struct sctp_remote_error {
uint16_t sre_type; uint16_t sre_type;
skipping to change at page 40, line 15 skipping to change at page 46, line 29
struct sctp_remote_error { struct sctp_remote_error {
uint16_t sre_type; uint16_t sre_type;
uint16_t sre_flags; uint16_t sre_flags;
uint32_t sre_length; uint32_t sre_length;
uint16_t sre_error; uint16_t sre_error;
sctp_assoc_t sre_assoc_id; sctp_assoc_t sre_assoc_id;
uint8_t sre_data[]; uint8_t sre_data[];
}; };
sre_type: It should be SCTP_REMOTE_ERROR. sre_type: It should be SCTP_REMOTE_ERROR.
sre_flags: Currently unused. sre_flags: Currently unused.
sre_length: This field is the total length of the notification data, sre_length: This field is the total length of the notification data,
including the notification header and the contents of sre_data. including the notification header and the contents of sre_data.
sre_error: This value represents one of the Operational Error causes sre_error: This value represents one of the Operational Error causes
defined in the SCTP specification, in network byte order. defined in the SCTP specification, in network byte order.
sre_assoc_id: The association id field holds the identifier for the sre_assoc_id: The association id field holds the identifier for the
association. All notifications for a given association have the association. All notifications for a given association have the
same association identifier. For a one-to-one style socket, this same association identifier. For a one-to-one style socket, this
field is ignored. field is ignored.
sre_data: This contains the ERROR chunk as defined in the SCTP sre_data: This contains the ERROR chunk as defined in the SCTP
specification [RFC4960] Section 3.3.10. specification [RFC4960] Section 3.3.10.
5.3.5. SCTP_SEND_FAILED 6.1.4. SCTP_SEND_FAILED - DEPRECATED
Please note that this notification is deprecated. Use Please note that this notification is deprecated. Use
SCTP_SEND_FAILED_EVENT instead. SCTP_SEND_FAILED_EVENT instead.
If SCTP cannot deliver a message, it can return back the message as a If SCTP cannot deliver a message, it can return back the message as a
notification if the SCTP_SEND_FAILED event is enabled. The notification if the SCTP_SEND_FAILED event is enabled. The
notification has the following format: notification has the following format:
struct sctp_send_failed { struct sctp_send_failed {
uint16_t ssf_type; uint16_t ssf_type;
skipping to change at page 40, line 47 skipping to change at page 47, line 17
uint16_t ssf_type; uint16_t ssf_type;
uint16_t ssf_flags; uint16_t ssf_flags;
uint32_t ssf_length; uint32_t ssf_length;
uint32_t ssf_error; uint32_t ssf_error;
struct sctp_sndrcvinfo ssf_info; struct sctp_sndrcvinfo ssf_info;
sctp_assoc_t ssf_assoc_id; sctp_assoc_t ssf_assoc_id;
uint8_t ssf_data[]; uint8_t ssf_data[];
}; };
ssf_type: It should be SCTP_SEND_FAILED. ssf_type: It should be SCTP_SEND_FAILED.
ssf_flags: The flag value will take one of the following values: ssf_flags: The flag value will take one of the following values:
SCTP_DATA_UNSENT: Indicates that the data was never put on the SCTP_DATA_UNSENT: Indicates that the data was never put on the
wire. wire.
SCTP_DATA_SENT: Indicates that the data was put on the wire. SCTP_DATA_SENT: Indicates that the data was put on the wire.
Note that this does not necessarily mean that the data was (or Note that this does not necessarily mean that the data was (or
was not) successfully delivered. was not) successfully delivered.
ssf_length: This field is the total length of the notification data, ssf_length: This field is the total length of the notification data,
including the notification header and the payload in ssf_data. including the notification header and the payload in ssf_data.
ssf_error: This value represents the reason why the send failed, and ssf_error: This value represents the reason why the send failed, and
if set, will be an SCTP protocol error code as defined in if set, will be an SCTP protocol error code as defined in
[RFC4960] Section 3.3.10. [RFC4960] Section 3.3.10.
ssf_info: The send information associated with the undelivered
message. The ssf_info.sinfo_flags field will also contain an ssf_info: The ancillary data (struct sctp_sndrcvinfo) used to send
indication if the beginning of the message and/or end of the the undelivered message. Regardless of if ancillary data is used
message is present. In cases where no data has been sent on the or not, the ssf_info.sinfo_flags field indicates if the complete
wire, this field will have or'ed-in the value SCTP_DATA_NOT_FRAG, message or only part of the message is returned in ssf_data. If
which is a composition of both a "BEGIN" and "END" fragmentation only part of the message is returned, it means that the part which
bit. In cases where only part of the data has been sent, this is not present has been sent successfully to the peer.
field will have or'ed in the value SCTP_DATA_LAST_FRAG, which
corresponds to the "END" bit. Note that the message itself may be If the complete message cannot be sent, the SCTP_DATA_NOT_FRAG
more than one chunk. If the ssf_info.sinfo_flags field holds flags is set in ssf_info.sinfo_flags. If the first part of the
neither of these two values then a piece that has been fragmented message is sent successfully, the SCTP_DATA_LAST_FRAG is set.
and sent but not acknowledged is present. This piece is from an This means that the tail end of the message is returned in
unspecified position in the message and the application can make ssf_data.
no assumptions about the data itself. Applications wanting to
examine a recovered message should look for the
SCTP_DATA_NOT_FRAG. Without this flag the application should
assume part of the message arrived and take appropriate steps to
audit and recover any lost or missing data.
ssf_assoc_id: The association id field, ssf_assoc_id, holds the ssf_assoc_id: The association id field, ssf_assoc_id, holds the
identifier for the association. All notifications for a given identifier for the association. All notifications for a given
association have the same association identifier. For a one-to- association have the same association identifier. For a one-to-
one style socket, this field is ignored. one style socket, this field is ignored.
ssf_data: The undelivered message or part of the undelivered message ssf_data: The undelivered message or part of the undelivered message
will be present in the ssf_data field. Note that the will be present in the ssf_data field. Note that the
ssf_info.sinfo_flags field as noted above should be used to ssf_info.sinfo_flags field as noted above should be used to
determine if a complete message is present or just a piece of the determine if a complete message is present or just a piece of the
message. Note that only user data is present in this field, any message. Note that only user data is present in this field, any
chunk headers or SCTP common headers must be removed by the SCTP chunk headers or SCTP common headers must be removed by the SCTP
stack. stack.
5.3.6. SCTP_SHUTDOWN_EVENT 6.1.5. SCTP_SHUTDOWN_EVENT
When a peer sends a SHUTDOWN, SCTP delivers this notification to When a peer sends a SHUTDOWN, SCTP delivers this notification to
inform the application that it should cease sending data. inform the application that it should cease sending data.
struct sctp_shutdown_event { struct sctp_shutdown_event {
uint16_t sse_type; uint16_t sse_type;
uint16_t sse_flags; uint16_t sse_flags;
uint32_t sse_length; uint32_t sse_length;
sctp_assoc_t sse_assoc_id; sctp_assoc_t sse_assoc_id;
}; };
sse_type: It should be SCTP_SHUTDOWN_EVENT. sse_type: It should be SCTP_SHUTDOWN_EVENT.
sse_flags: Currently unused. sse_flags: Currently unused.
sse_length: This field is the total length of the notification data, sse_length: This field is the total length of the notification data,
including the notification header. It will generally be sizeof including the notification header. It will generally be
(struct sctp_shutdown_event). sizeof(struct sctp_shutdown_event).
sse_flags: Currently unused. sse_flags: Currently unused.
sse_assoc_id: The association id field holds the identifier for the sse_assoc_id: The association id field holds the identifier for the
association. All notifications for a given association have the association. All notifications for a given association have the
same association identifier. For a one-to-one style socket, this same association identifier. For a one-to-one style socket, this
field is ignored. field is ignored.
5.3.7. SCTP_ADAPTATION_INDICATION 6.1.6. SCTP_ADAPTATION_INDICATION
When a peer sends an Adaptation Layer Indication parameter as When a peer sends an Adaptation Layer Indication parameter as
described in [RFC5061], SCTP delivers this notification to inform the described in [RFC5061], SCTP delivers this notification to inform the
application about the peer's adaptation layer indication. application about the peer's adaptation layer indication.
struct sctp_adaptation_event { struct sctp_adaptation_event {
uint16_t sai_type; uint16_t sai_type;
uint16_t sai_flags; uint16_t sai_flags;
uint32_t sai_length; uint32_t sai_length;
uint32_t sai_adaptation_ind; uint32_t sai_adaptation_ind;
skipping to change at page 42, line 31 skipping to change at page 49, line 4
described in [RFC5061], SCTP delivers this notification to inform the described in [RFC5061], SCTP delivers this notification to inform the
application about the peer's adaptation layer indication. application about the peer's adaptation layer indication.
struct sctp_adaptation_event { struct sctp_adaptation_event {
uint16_t sai_type; uint16_t sai_type;
uint16_t sai_flags; uint16_t sai_flags;
uint32_t sai_length; uint32_t sai_length;
uint32_t sai_adaptation_ind; uint32_t sai_adaptation_ind;
sctp_assoc_t sai_assoc_id; sctp_assoc_t sai_assoc_id;
}; };
sai_type: It should be SCTP_ADAPTATION_INDICATION. sai_type: It should be SCTP_ADAPTATION_INDICATION.
sai_flags: Currently unused. sai_flags: Currently unused.
sai_length: This field is the total length of the notification data, sai_length: This field is the total length of the notification data,
including the notification header. It will generally be sizeof including the notification header. It will generally be
(struct sctp_adaptation_event). sizeof(struct sctp_adaptation_event).
sai_adaptation_ind: This field holds the bit array sent by the peer sai_adaptation_ind: This field holds the bit array sent by the peer
in the adaptation layer indication parameter. The bits are in in the adaptation layer indication parameter.
network byte order.
sai_assoc_id: The association id field holds the identifier for the sai_assoc_id: The association id field holds the identifier for the
association. All notifications for a given association have the association. All notifications for a given association have the
same association identifier. For a one-to-one style socket, this same association identifier. For a one-to-one style socket, this
field is ignored. field is ignored.
5.3.8. SCTP_PARTIAL_DELIVERY_EVENT 6.1.7. SCTP_PARTIAL_DELIVERY_EVENT
When a receiver is engaged in a partial delivery of a message this When a receiver is engaged in a partial delivery of a message this
notification will be used to indicate various events. notification will be used to indicate various events.
struct sctp_pdapi_event { struct sctp_pdapi_event {
uint16_t pdapi_type; uint16_t pdapi_type;
uint16_t pdapi_flags; uint16_t pdapi_flags;
uint32_t pdapi_length; uint32_t pdapi_length;
uint32_t pdapi_indication; uint32_t pdapi_indication;
uint32_t pdapi_stream; uint32_t pdapi_stream;
skipping to change at page 43, line 16 skipping to change at page 49, line 36
uint16_t pdapi_type; uint16_t pdapi_type;
uint16_t pdapi_flags; uint16_t pdapi_flags;
uint32_t pdapi_length; uint32_t pdapi_length;
uint32_t pdapi_indication; uint32_t pdapi_indication;
uint32_t pdapi_stream; uint32_t pdapi_stream;
uint32_t pdapi_seq; uint32_t pdapi_seq;
sctp_assoc_t pdapi_assoc_id; sctp_assoc_t pdapi_assoc_id;
}; };
pdapi_type: It should be SCTP_PARTIAL_DELIVERY_EVENT. pdapi_type: It should be SCTP_PARTIAL_DELIVERY_EVENT.
pdapi_flags: Currently unused. pdapi_flags: Currently unused.
pdapi_length: This field is the total length of the notification pdapi_length: This field is the total length of the notification
data, including the notification header. It will generally be data, including the notification header. It will generally be
sizeof(struct sctp_pdapi_event). sizeof(struct sctp_pdapi_event).
pdapi_indication: This field holds the indication being sent to the pdapi_indication: This field holds the indication being sent to the
application. Currently there is only one defined value: application. Currently there is only one defined value:
SCTP_PARTIAL_DELIVERY_ABORTED: This indicates that the partial SCTP_PARTIAL_DELIVERY_ABORTED: This indicates that the partial
delivery of a user message has been aborted. This happens, for delivery of a user message has been aborted. This happens, for
example, if an association is aborted while a partial delivery example, if an association is aborted while a partial delivery
is going on or the user message gets abandoned using PR-SCTP is going on or the user message gets abandoned using PR-SCTP
while the partial delivery of this message is going on. while the partial delivery of this message is going on.
pdapi_stream: This field holds the stream on which the partial pdapi_stream: This field holds the stream on which the partial
delivery event happened. delivery event happened.
pdapi_seq: This field holds the stream sequence number which was pdapi_seq: This field holds the stream sequence number which was
being partially delivered. being partially delivered.
pdapi_assoc_id: The association id field holds the identifier for pdapi_assoc_id: The association id field holds the identifier for
the association. All notifications for a given association have the association. All notifications for a given association have
the same association identifier. For a one-to-one style socket the same association identifier. For a one-to-one style socket
this field is ignored. this field is ignored.
5.3.9. SCTP_AUTHENTICATION_EVENT 6.1.8. SCTP_AUTHENTICATION_EVENT
[RFC4895] defines an extension to authenticate SCTP messages. The [RFC4895] defines an extension to authenticate SCTP messages. The
following notification is used to report different events relating to following notification is used to report different events relating to
the use of this extension. the use of this extension.
struct sctp_authkey_event { struct sctp_authkey_event {
uint16_t auth_type; uint16_t auth_type;
uint16_t auth_flags; uint16_t auth_flags;
uint32_t auth_length; uint32_t auth_length;
uint16_t auth_keynumber; uint16_t auth_keynumber;
skipping to change at page 44, line 4 skipping to change at page 50, line 30
the use of this extension. the use of this extension.
struct sctp_authkey_event { struct sctp_authkey_event {
uint16_t auth_type; uint16_t auth_type;
uint16_t auth_flags; uint16_t auth_flags;
uint32_t auth_length; uint32_t auth_length;
uint16_t auth_keynumber; uint16_t auth_keynumber;
uint32_t auth_indication; uint32_t auth_indication;
sctp_assoc_t auth_assoc_id; sctp_assoc_t auth_assoc_id;
}; };
auth_type: It should be SCTP_AUTHENTICATION_EVENT. auth_type: It should be SCTP_AUTHENTICATION_EVENT.
auth_flags: Currently unused. auth_flags: Currently unused.
auth_length: This field is the total length of the notification auth_length: This field is the total length of the notification
data, including the notification header. It will generally be data, including the notification header. It will generally be
sizeof (struct sctp_authkey_event). sizeof(struct sctp_authkey_event).
auth_keynumber: This field holds the keynumber for the affected key auth_keynumber: This field holds the keynumber for the affected key
indicated in the event (depends on auth_indication). indicated in the event (depends on auth_indication).
auth_indication: This field holds the error or indication being auth_indication: This field holds the error or indication being
reported. The following values are currently defined: reported. The following values are currently defined:
SCTP_AUTH_NEW_KEY: This report indicates that a new key has been SCTP_AUTH_NEW_KEY: This report indicates that a new key has been
made active (used for the first time by the peer) and is now made active (used for the first time by the peer) and is now
the active key. The auth_keynumber field holds the user the active key. The auth_keynumber field holds the user
specified key number. specified key number.
SCTP_AUTH_NO_AUTH: This report indicates that the peer does not SCTP_AUTH_NO_AUTH: This report indicates that the peer does not
support SCTP AUTH as defined in [RFC4895]. support SCTP AUTH as defined in [RFC4895].
SCTP_AUTH_FREE_KEY: This report indicates that the SCTP SCTP_AUTH_FREE_KEY: This report indicates that the SCTP
implementation will not use the key identifier specified in implementation will no longer use the key identifier specified
auth_keynumber anymore. in auth_keynumber.
auth_assoc_id: The association id field holds the identifier for the auth_assoc_id: The association id field holds the identifier for the
association. All notifications for a given association have the association. All notifications for a given association have the
same association identifier. For a one-to-one style socket this same association identifier. For a one-to-one style socket this
field is ignored. field is ignored.
5.3.10. SCTP_SENDER_DRY_EVENT 6.1.9. SCTP_SENDER_DRY_EVENT
When the SCTP implementation has no user data anymore to send or When the SCTP stack has no more user data to send or retransmit, this
retransmit, this notification is given to the user. If the user notification is given to the user. Also, at the time when a user app
subscribes to this event and SCTP has no user data to send or subscribes to this event, if there is no data to be sent or
retransmit at this point of time, this notification is also given to retransmit, the stack will immediately send up this notification.
the user.
struct sctp_sender_dry_event { struct sctp_sender_dry_event {
uint16_t sender_dry_type; uint16_t sender_dry_type;
uint16_t sender_dry_flags; uint16_t sender_dry_flags;
uint32_t sender_dry_length; uint32_t sender_dry_length;
sctp_assoc_t sender_dry_assoc_id; sctp_assoc_t sender_dry_assoc_id;
}; };
sender_dry_type: It should be SCTP_SENDER_DRY_EVENT. sender_dry_type: It should be SCTP_SENDER_DRY_EVENT.
sender_dry_flags: Currently unused. sender_dry_flags: Currently unused.
sender_dry_length: This field is the total length of the sender_dry_length: This field is the total length of the
notification data, including the notification header. It will notification data, including the notification header. It will
generally be sizeof(struct sctp_sender_dry_event). generally be sizeof(struct sctp_sender_dry_event).
sender_dry_assoc_id: The association id field holds the identifier sender_dry_assoc_id: The association id field holds the identifier
for the association. All notifications for a given association for the association. All notifications for a given association
have the same association identifier. For a one-to-one style have the same association identifier. For a one-to-one style
socket this field is ignored. socket this field is ignored.
5.3.11. SCTP_NOTIFICATIONS_STOPPED_EVENT 6.1.10. SCTP_NOTIFICATIONS_STOPPED_EVENT
Notifications, when subscribed to, are reliable. They are always SCTP notifications, when subscribed to, are reliable. They are
delivered as long as there is space in the socket receive buffer. always delivered as long as there is space in the socket receive
However, if an implementation experiences a notification storm, it buffer. However, if an implementation experiences a notification
may run out of socket buffer space. When this occurs it may wish to storm, it may run out of socket buffer space. When this occurs it
disable notifications. If the implementation chooses to do this, it may wish to disable notifications. If the implementation chooses to
will append a final notification SCTP_NOTIFICATIONS_STOPPED_EVENT. do this, it will append a final notification
This notification is a union sctp_notification, where only the struct SCTP_NOTIFICATIONS_STOPPED_EVENT. This notification is a union
sctp_tlv (see the union above) is used. It only contains this type sctp_notification, where only the struct sctp_tlv (see the union
in the sn_type field, the sn_length field set to the sizeof an above) is used. It only contains this type in the sn_type field, the
sctp_tlv structure and the sn_flags set to 0. If an application sn_length field set to the sizeof an sctp_tlv structure and the
receives this notification, it will need to resubscribe to any sn_flags set to 0. If an application receives this notification, it
notifications of interest to it, except for the data io event. will need to re-subscribe to any notifications of interest to it,
except for the sctp_data_io_event (note that SCTP_EVENTS is
deprecated).
An endpoint is automatically subscribed to this event as soon as it An endpoint is automatically subscribed to this event as soon as it
is subscribed to any event other than data io events. is subscribed to any event other than data io events.
5.3.12. SCTP_SEND_FAILED_EVENT 6.1.11. SCTP_SEND_FAILED_EVENT
If SCTP cannot deliver a message, it can return back the message as a If SCTP cannot deliver a message, it can return back the message as a
notification if the SCTP_SEND_FAILED_EVENT event is enabled. The notification if the SCTP_SEND_FAILED_EVENT event is enabled. The
notification has the following format: notification has the following format:
struct sctp_send_failed { struct sctp_send_failed_event {
uint16_t ssf_type; uint16_t ssfe_type;
uint16_t ssf_flags; uint16_t ssfe_flags;
uint32_t ssf_length; uint32_t ssfe_length;
uint32_t ssf_error; uint32_t ssfe_error;
struct sctp_sndinfo ssf_info; struct sctp_sndinfo ssfe_info;
sctp_assoc_t ssf_assoc_id; sctp_assoc_t ssfe_assoc_id;
uint8_t ssf_data[]; uint8_t ssfe_data[];
}; };
ssf_type: It should be SCTP_SEND_FAILED_EVENT. ssfe_type: It should be SCTP_SEND_FAILED_EVENT.
ssf_flags: The flag value will take one of the following values:
ssfe_flags: The flag value will take one of the following values:
SCTP_DATA_UNSENT: Indicates that the data was never put on the SCTP_DATA_UNSENT: Indicates that the data was never put on the
wire. wire.
SCTP_DATA_SENT: Indicates that the data was put on the wire. SCTP_DATA_SENT: Indicates that the data was put on the wire.
Note that this does not necessarily mean that the data was (or Note that this does not necessarily mean that the data was (or
was not) successfully delivered. was not) successfully delivered.
ssf_length: This field is the total length of the notification data,
including the notification header and the payload in ssf_data. ssfe_length: This field is the total length of the notification
ssf_error: This value represents the reason why the send failed, and data, including the notification header and the payload in
if set, will be an SCTP protocol error code as defined in ssf_data.
ssfe_error: This value represents the reason why the send failed,
and if set, will be an SCTP protocol error code as defined in
[RFC4960] Section 3.3.10. [RFC4960] Section 3.3.10.
ssf_info: The send information associated with the undelivered ssfe_info: The ancillary data (struct sctp_sndinfo) used to send the
message. The ssf_info.snd_flags field will also contain an undelivered message. Regardless of if ancillary data is used or
indication if the beginning of the message and/or end of the not, the ssfe_info.sinfo_flags field indicates if the complete
message is present. In cases where no data has been sent on the message or only part of the message is returned in ssf_data. If
wire, this field will have or'ed in the value SCTP_DATA_NOT_FRAG, only part of the message is returned, it means that the part which
which is a composition of both a "BEGIN" and "END" fragmentation is not present has been sent successfully to the peer.
bit. In cases where only part of the data has been sent, this
field will have or'ed in the value SCTP_DATA_LAST_FRAG, which If the complete message cannot be sent, the SCTP_DATA_NOT_FRAG
corresponds to the "END" bit. Note that the message itself may be flags is set in ssfe_info.sinfo_flags. If the first part of the
more than one chunk. If the ssf_info.snd_flags field holds message is sent successfully, the SCTP_DATA_LAST_FRAG is set.
neither of these two values then a piece that has been fragmented This means that the tail end of the message is returned in
and sent but not acknowledged is present. This piece is from an ssf_data.
unspecified position in the message and the application can make
no assumptions about the data itself. Applications wanting to ssfe_assoc_id: The association id field, ssf_assoc_id, holds the
examine a recovered message should look for the
SCTP_DATA_NOT_FRAG. Without this flag the application should
assume part of the message arrived and take appropriate steps to
audit and recover any lost or missing data.
ssf_assoc_id: The association id field, ssf_assoc_id, holds the
identifier for the association. All notifications for a given identifier for the association. All notifications for a given
association have the same association identifier. For a one-to- association have the same association identifier. For a one-to-
one style socket, this field is ignored. one style socket, this field is ignored.
ssf_data: The undelivered message or part of the undelivered message
will be present in the ssf_data field. Note that the ssfe_data: The undelivered message or part of the undelivered
message will be present in the ssf_data field. Note that the
ssf_info.sinfo_flags field as noted above should be used to ssf_info.sinfo_flags field as noted above should be used to
determine if a complete message is present or just a piece of the determine if a complete message is present or just a piece of the
message. Note that only user data is present in this field, any message. Note that only user data is present in this field, any
chunk headers or SCTP common headers must be removed by the SCTP chunk headers or SCTP common headers must be removed by the SCTP
stack. stack.
5.4. Ancillary Data Considerations and Semantics 6.2. Notification Interest Options
Programming with ancillary socket data contains some subtleties and 6.2.1. SCTP_EVENTS option - DEPRECATED
pitfalls, which are discussed below.
5.4.1. Multiple Items and Ordering To receive SCTP event notifications, an application registers its
interest by setting the SCTP_EVENTS socket option. The application
then uses recvmsg() to retrieve notifications. A notification is
stored in the data part (msg_iov) of the struct msghdr. The socket
option uses the following structure:
Multiple ancillary data items may be included in any call to struct sctp_event_subscribe {
sendmsg() or recvmsg(); these may include multiple SCTP or non-SCTP uint8_t sctp_data_io_event;
items, or both. uint8_t sctp_association_event;
uint8_t sctp_address_event;
uint8_t sctp_send_failure_event;
uint8_t sctp_peer_error_event;
uint8_t sctp_shutdown_event;
uint8_t sctp_partial_delivery_event;
uint8_t sctp_adaptation_layer_event;
uint8_t sctp_authentication_event;
uint8_t sctp_sender_dry_event;
};
sctp_data_io_event: Setting this flag to 1 will cause the reception
of SCTP_SNDRCV information on a per message basis. The
application will need to use the recvmsg() interface so that it
can receive the event information contained in the msg_control
field. Setting the flag to 0 will disable the reception of the
message control information. Note that this is not really a
notification and this is stored in the ancillary data
(msg_control), not in the data part (msg_iov).
The ordering of ancillary data items (either by SCTP or another sctp_association_event: Setting this flag to 1 will enable the
protocol) is not significant and is implementation-dependent, so reception of association event notifications. Setting the flag to
applications must not depend on any ordering. 0 will disable association event notifications.
SCTP_SNDRCV/SCTP_SNDINFO/SCTP_RCVINFO type ancillary data always sctp_address_event: Setting this flag to 1 will enable the reception
correspond to the data in the msghdr's msg_iov member. There can be of address event notifications. Setting the flag to 0 will
only one single such type ancillary data for each sendmsg() or disable address event notifications.
recvmsg() call.
5.4.2. Accessing and Manipulating Ancillary Data sctp_send_failure_event: Setting this flag to 1 will enable the
reception of send failure event notifications. Setting the flag
to 0 will disable send failure event notifications.
Applications can infer the presence of data or ancillary data by sctp_peer_error_event: Setting this flag to 1 will enable the
examining the msg_iovlen and msg_controllen msghdr members, reception of peer error event notifications. Setting the flag to
respectively. 0 will disable peer error event notifications.
Implementations may have different padding requirements for ancillary sctp_shutdown_event: Setting this flag to 1 will enable the
data, so portable applications should make use of the macros reception of shutdown event notifications. Setting the flag to 0
CMSG_FIRSTHDR, CMSG_NXTHDR, CMSG_DATA, CMSG_SPACE, and CMSG_LEN. See will disable shutdown event notifications.
[RFC3542] and the SCTP implementation's documentation for more
information. The following is an example, from [RFC3542],
demonstrating the use of these macros to access ancillary data:
struct msghdr msg; sctp_partial_delivery_event: Setting this flag to 1 will enable the
struct cmsghdr *cmsgptr; reception of partial delivery notifications. Setting the flag to
0 will disable partial delivery event notifications.
/* fill in msg */ sctp_adaptation_layer_event: Setting this flag to 1 will enable the
reception of adaptation layer notifications. Setting the flag to
0 will disable adaptation layer event notifications.
/* call recvmsg() */ sctp_authentication_event: Setting this flag to 1 will enable the
reception of authentication layer notifications. Setting the flag
to 0 will disable authentication layer event notifications.
for (cmsgptr = CMSG_FIRSTHDR(&msg); cmsgptr != NULL; sctp_sender_dry_event: Setting this flag to 1 will enable the
cmsgptr = CMSG_NXTHDR(&msg, cmsgptr)) { reception of sender dry notifications. Setting the flag to 0 will
if (cmsgptr->cmsg_level == ... && cmsgptr->cmsg_type == ... ) { disable sender dry event notifications.
u_char *ptr;
ptr = CMSG_DATA(cmsgptr); An example where an application would like to receive data io events
/* process data pointed to by ptr */ and association events but no others would be as follows:
}
{
struct sctp_event_subscribe events;
memset(&events,0,sizeof(events));
events.sctp_data_io_event = 1;
events.sctp_association_event = 1;
setsockopt(fd, IPPROTO_SCTP, SCTP_EVENTS, &events, sizeof(events));
} }
5.4.3. Control Message Buffer Sizing Note that for one-to-many style SCTP sockets, the caller of recvmsg()
receives ancillary data and notifications for all associations bound
to the file descriptor. For one-to-one style SCTP sockets, the
caller receives ancillary data and notifications only for the single
association bound to the file descriptor.
The information conveyed via SCTP_SNDRCV/SCTP_SNDINFO/SCTP_RCVINFO By default both the one-to-one style and the one-to-many style socket
ancillary data will often be fundamental to the correct and sane do not subscribe to any notification.
operation of the sockets application. This is particularly true of
the one-to-many semantics, but also of the one-to-one semantics. For
example, if an application needs to send and receive data on
different SCTP streams, SCTP_SNDRCV/SCTP_SNDINFO/SCTP_RCVINFO
ancillary data is indispensable.
Given that some ancillary data is critical, and that multiple 6.2.2. SCTP_EVENT option
ancillary data items may appear in any order, applications should be
carefully written to always provide a large enough buffer to contain
all possible ancillary data that can be presented by recvmsg(). If
the buffer is too small, and crucial data is truncated, it may pose a
fatal error condition.
Thus, it is essential that applications be able to deterministically The SCTP_EVENTS socket option has one issue for future compatibility.
calculate the maximum required buffer size to pass to recvmsg(). One As new features are added the structure (sctp_event_subscribe) must
constraint imposed on this specification that makes this possible is be expanded. This can cause an application binary interface (ABI)
that all ancillary data definitions are of a fixed length. One way issue unless an implementation has added padding at the end of the
to calculate the maximum required buffer size might be to take the structure. To avoid this problem, SCTP_EVENTS has been deprecated
sum the sizes of all enabled ancillary data item structures, as and a new socket option SCTP_EVENT has taken its place. The option
calculated by CMSG_SPACE. For example, if we enabled is used with the following structure:
SCTP_SNDRCV_INFO and IPV6_RECVPKTINFO [RFC3542], we would calculate
and allocate the buffer size as follows:
size_t total; struct sctp_event {
void *buf; sctp_assoc_t se_assoc_id;
uint16_t se_type;
uint8_t se_on;
};
total = CMSG_SPACE(sizeof (struct sctp_sndrcvinfo)) + se_assoc_id: The se_assoc_id field is ignored for one-to-one style
CMSG_SPACE(sizeof (struct in6_pktinfo)); sockets. For one-to-many style sockets this field can be a
particular association id or SCTP_{FUTURE|CURRENT|ALL}_ASSOC.
buf = malloc(total); se_type: The se_type field can be filled with any value that would
show up in the respective sn_type field (in the sctp_tlv structure
of the notification).
We could then use this buffer (buf) for msg_control on each call to se_on: The se_on field is set to 1 to turn on an event and set to 0
recvmsg() and be assured that we would not lose any ancillary data to to turn off an event.
truncation.
6. Common Operations for Both Styles To use this option the user fills in this structure and then calls
the setsockopt to turn on or off an individual event. The following
is an example use of this option:
6.1. send(), recv(), sendto(), and recvfrom() {
struct sctp_event event;
memset(&event, 0, sizeof(event));
event.se_assoc_id = SCTP_FUTURE_ASSOC;
event.se_type = SCTP_SENDER_DRY_EVENT;
event.se_on = 1;
setsockopt(fd, IPPROTO_SCTP, SCTP_EVENT, &event, sizeof(event));
}
By default both the one-to-one style and the one-to-many style socket
do not subscribe to any notification.
7. Common Operations for Both Styles
7.1. send(), recv(), sendto(), and recvfrom()
Applications can use send() and sendto() to transmit data to the peer Applications can use send() and sendto() to transmit data to the peer
of an SCTP endpoint. recv() and recvfrom() can be used to receive of an SCTP endpoint. recv() and recvfrom() can be used to receive
data from the peer. data from the peer.
The function prototypes are The function prototypes are
ssize_t send(int sd, ssize_t send(int sd,
const void *msg, const void *msg,
size_t len, size_t len,
skipping to change at page 50, line 6 skipping to change at page 58, line 9
SCTP is message based. The msg buffer above in send() and sendto() SCTP is message based. The msg buffer above in send() and sendto()
is considered to be a single message. This means that if the caller is considered to be a single message. This means that if the caller
wants to send a message that is composed by several buffers, the wants to send a message that is composed by several buffers, the
caller needs to combine them before calling send() or sendto(). caller needs to combine them before calling send() or sendto().
Alternately, the caller can use sendmsg() to do that without Alternately, the caller can use sendmsg() to do that without
combining them. Sending a message using send() or sendto() is atomic combining them. Sending a message using send() or sendto() is atomic
unless explicit EOR marking is enabled on the socket specified by sd. unless explicit EOR marking is enabled on the socket specified by sd.
Using sendto() on a non-connected one-to-one style socket for Using sendto() on a non-connected one-to-one style socket for
implicit connection setup may or may not work depending on the SCTP implicit connection setup may or may not work depending on the SCTP
implementation. recv() and recvfrom() cannot distinguish message implementation. recv() and recvfrom() cannot distinguish message
boundaries. boundaries (i.e. there is no way to observe the MSG_EOR flag to
detect partial delivery).
In receiving, if the buffer supplied is not large enough to hold a In receiving, if the buffer supplied is not large enough to hold a
complete message, the receive call acts like a stream socket and complete message, the receive call acts like a stream socket and
returns as much data as will fit in the buffer. returns as much data as will fit in the buffer.
Note, the send() and recv() calls may not be used for a one-to-many Note, the send() and recv() calls may not be used for a one-to-many
style socket. style socket.
Note, if an application calls a send() or sendto() function with no Note, if an application calls a send() or sendto() function with no
user data the SCTP implementation should reject the request with an user data the SCTP implementation should reject the request with an
appropriate error message. An implementation is not allowed to send appropriate error message. An implementation is not allowed to send
a DATA chunk with no user data [RFC4960]. a DATA chunk with no user data [RFC4960].
6.2. setsockopt() and getsockopt() 7.2. setsockopt() and getsockopt()
Applications use setsockopt() and getsockopt() to set or retrieve Applications use setsockopt() and getsockopt() to set or retrieve
socket options. Socket options are used to change the default socket options. Socket options are used to change the default
behavior of socket calls. They are described in Section 7. behavior of socket calls. They are described in Section 8.
The function prototypes are The function prototypes are
int getsockopt(int sd, int getsockopt(int sd,
int level, int level,
int optname, int optname,
void *optval, void *optval,
socklen_t *optlen); socklen_t *optlen);
and and
skipping to change at page 50, line 43 skipping to change at page 58, line 47
and and
int setsockopt(int sd, int setsockopt(int sd,
int level, int level,
int optname, int optname,
const void *optval, const void *optval,
socklen_t optlen); socklen_t optlen);
and the arguments are and the arguments are
sd: The socket descriptor. sd: The socket descriptor.
level: Set to IPPROTO_SCTP for all SCTP options. level: Set to IPPROTO_SCTP for all SCTP options.
optname: The option name. optname: The option name.
optval: The buffer to store the value of the option. optval: The buffer to store the value of the option.
optlen: The size of the buffer (or the length of the option optlen: The size of the buffer (or the length of the option
returned). returned).
They return 0 on success and -1 in case of an error. They return 0 on success and -1 in case of an error.
All socket options set on a one-to-one style listening socket also All socket options set on a one-to-one style listening socket also
apply to all accepted sockets. For one-to-many style sockets often a apply to all future accepted sockets. For one-to-many style sockets
socket option will pass a structure that includes an assoc_id field. often a socket option will pass a structure that includes an assoc_id
This field can be filled with the association id of a particular field. This field can be filled with the association id of a
association and unless otherwise specified can be filled with one of particular association and unless otherwise specified can be filled
the following constants: with one of the following constants:
SCTP_FUTURE_ASSOC: Specifies that only future associations created SCTP_FUTURE_ASSOC: Specifies that only future associations created
after this socket option will be affected by this call. after this socket option will be affected by this call.
SCTP_CURRENT_ASSOC: Specifies that only currently existing SCTP_CURRENT_ASSOC: Specifies that only currently existing
associations will be affected by this call, future associations associations will be affected by this call, future associations
will still receive the previous default value. will still receive the previous default value.
SCTP_ALL_ASSOC: Specifies that all current and future associations SCTP_ALL_ASSOC: Specifies that all current and future associations
will be affected by this call. will be affected by this call.
6.3. read() and write() 7.3. read() and write()
Applications can use read() and write() to send and receive data to Applications can use read() and write() to send and receive data to
and from a peer. They have the same semantics as send() and recv() and from a peer. They have the same semantics as send() and recv()
except that the flags parameter cannot be used. except that the flags parameter cannot be used.
6.4. getsockname() 7.4. getsockname()
Applications use getsockname() to retrieve the locally-bound socket Applications use getsockname() to retrieve the locally-bound socket
address of the specified socket. This is especially useful if the address of the specified socket. This is especially useful if the
caller let SCTP choose a local port. This call is for single homed caller let SCTP choose a local port. This call is for single homed
endpoints. It does not work well with multi-homed endpoints. See endpoints. It does not work well with multi-homed endpoints. See
Section 8.5 for a multi-homed version of the call. Section 9.5 for a multi-homed version of the call.
The function prototype is The function prototype is
int getsockname(int sd, int getsockname(int sd,
struct sockaddr *address, struct sockaddr *address,
socklen_t *len); socklen_t *len);
and the arguments are and the arguments are
sd: The socket descriptor to be queried. sd: The socket descriptor to be queried.
address: On return, one locally bound address (chosen by the SCTP address: On return, one locally bound address (chosen by the SCTP
stack) is stored in this buffer. If the socket is an IPv4 socket, stack) is stored in this buffer. If the socket is an IPv4 socket,
the address will be IPv4. If the socket is an IPv6 socket, the the address will be IPv4. If the socket is an IPv6 socket, the
address will be either an IPv6 or IPv4 address. address will be either an IPv6 or IPv4 address.
len: The caller should set the length of the address here. On len: The caller should set the length of the address here. On
return, this is set to the length of the returned address. return, this is set to the length of the returned address.
It returns 0 on success and -1 in case of an error. It returns 0 on success and -1 in case of an error.
If the actual length of the address is greater than the length of the If the actual length of the address is greater than the length of the
supplied sockaddr structure, the stored address will be truncated. supplied sockaddr structure, the stored address will be truncated.
If the socket has not been bound to a local name, the value stored in If the socket has not been bound to a local name, the value stored in
the object pointed to by address is unspecified. the object pointed to by address is unspecified.
6.5. Implicit Association Setup 7.5. Implicit Association Setup
The application can begin sending and receiving data using the The application can begin sending and receiving data using the
sendmsg()/recvmsg() or sendto()/recvfrom() calls, without going sendmsg()/recvmsg() or sendto()/recvfrom() calls, without going
through any explicit association setup procedures (i.e., no connect() through any explicit association setup procedures (i.e., no connect()
calls required). calls required).
Whenever sendmsg() or sendto() is called and the SCTP stack at the Whenever sendmsg() or sendto() is called and the SCTP stack at the
sender finds that no association exists between the sender and the sender finds that no association exists between the sender and the
intended receiver (identified by the address passed either in the intended receiver (identified by the address passed either in the
msg_name field of msghdr structure in the sendmsg() call or the msg_name field of msghdr structure in the sendmsg() call or the
skipping to change at page 52, line 30 skipping to change at page 60, line 50
will be dispatched to the socket at both the sender and receiver will be dispatched to the socket at both the sender and receiver
side. This notification can be read by the recvmsg() system call side. This notification can be read by the recvmsg() system call
(see Section 3.1.3). (see Section 3.1.3).
Note, if the SCTP stack at the sender side supports bundling, the Note, if the SCTP stack at the sender side supports bundling, the
first user message may be bundled with the COOKIE ECHO message first user message may be bundled with the COOKIE ECHO message
[RFC4960]. [RFC4960].
When the SCTP stack sets up a new association implicitly, the When the SCTP stack sets up a new association implicitly, the
SCTP_INIT type ancillary data may also be passed along (see SCTP_INIT type ancillary data may also be passed along (see
Section 5.2.1 for details of the data structures) to change some Section 5.3.1 for details of the data structures) to change some
parameters used in setting up a new association. parameters used in setting up a new association.
If this information is not present in the sendmsg() call, or if the If this information is not present in the sendmsg() call, or if the
implicit association setup is triggered by a sendto() call, the implicit association setup is triggered by a sendto() call, the
default association initialization parameters will be used. These default association initialization parameters will be used. These
default association parameters may be set with respective default association parameters may be set with respective
setsockopt() calls or be left to the system defaults. setsockopt() calls or be left to the system defaults.
Implicit association setup cannot be initiated by send() calls. Implicit association setup cannot be initiated by send() calls.
7. Socket Options 8. Socket Options
The following sub-section describes various SCTP level socket options The following sub-section describes various SCTP level socket options
that are common to both styles. SCTP associations can be multi- that are common to both styles. SCTP associations can be multi-
homed. Therefore, certain option parameters include a homed. Therefore, certain option parameters include a
sockaddr_storage structure to select which peer address the option sockaddr_storage structure to select which peer address the option
should be applied to. should be applied to.
For the one-to-many style sockets, an sctp_assoc_t (association ID) For the one-to-many style sockets, an sctp_assoc_t (association ID)
parameter is used to identify the association instance that the parameter is used to identify the association instance that the
operation affects. So it must be set when using this style. operation affects. So it must be set when using this style.
For the one-to-one style sockets and branched off one-to-many style For the one-to-one style sockets and branched off one-to-many style
sockets (see Section 8.2) this association ID parameter is ignored. sockets (see Section 9.2) this association ID parameter is ignored.
Note that socket or IP level options are set or retrieved per socket. Note that socket or IP level options are set or retrieved per socket.
This means that for one-to-many style sockets, the options will be This means that for one-to-many style sockets, the options will be
applied to all associations (similar to using SCTP_ALL_ASSOC as the applied to all associations (similar to using SCTP_ALL_ASSOC as the
association ID) belonging to the socket. For one-to-one style, these association ID) belonging to the socket. For one-to-one style, these
options will be applied to all peer addresses of the association options will be applied to all peer addresses of the association
controlled by the socket. Applications should be careful in setting controlled by the socket. Applications should be careful in setting
those options. those options.
For some IP stacks getsockopt() is read-only; so a new interface will For some IP stacks getsockopt() is read-only; so a new interface will
skipping to change at page 53, line 35 skipping to change at page 62, line 7
The sctp_opt_info() call is a replacement for getsockopt() only and The sctp_opt_info() call is a replacement for getsockopt() only and
will not set any options associated with the specified socket. A will not set any options associated with the specified socket. A
setsockopt() must be used to set any writeable option. setsockopt() must be used to set any writeable option.
For one-to-many style sockets, id specifies the association to query. For one-to-many style sockets, id specifies the association to query.
For one-to-one style sockets, id is ignored. For one-to-many For one-to-one style sockets, id is ignored. For one-to-many
sockets, any association identifier in the structure provided as arg sockets, any association identifier in the structure provided as arg
is ignored and id takes precedence. is ignored and id takes precedence.
Note that SCTP_CURRENT_ASSOC and SCTP_ALL_ASSOC cannot be used here. Note that SCTP_CURRENT_ASSOC and SCTP_ALL_ASSOC cannot be used with
Using them will result in an error (returning -1 and errno set to sctp_opt_info() or in getsockopt() calls. Using them will result in
EINVAL). SCTP_FUTURE_ASSOC can be used to query information for an error (returning -1 and errno set to EINVAL). SCTP_FUTURE_ASSOC
future associations. can be used to query information for future associations.
The field opt specifies which SCTP socket option to get. It can get The field opt specifies which SCTP socket option to get. It can get
any socket option currently supported that requests information any socket option currently supported that requests information
(either read/write options or read only) such as: (either read/write options or read only) such as:
SCTP_RTOINFO SCTP_RTOINFO
SCTP_ASSOCINFO SCTP_ASSOCINFO
SCTP_DEFAULT_SEND_PARAM SCTP_DEFAULT_SEND_PARAM
SCTP_GET_PEER_ADDR_INFO SCTP_GET_PEER_ADDR_INFO
SCTP_PRIMARY_ADDR SCTP_PRIMARY_ADDR
SCTP_PEER_ADDR_PARAMS SCTP_PEER_ADDR_PARAMS
SCTP_STATUS SCTP_STATUS
SCTP_CONTEXT SCTP_CONTEXT
SCTP_AUTH_ACTIVE_KEY SCTP_AUTH_ACTIVE_KEY
SCTP_PEER_AUTH_CHUNKS SCTP_PEER_AUTH_CHUNKS
SCTP_LOCAL_AUTH_CHUNKS SCTP_LOCAL_AUTH_CHUNKS
The arg field is an option-specific structure buffer provided by the The arg field is an option-specific structure buffer provided by the
caller. See Section 8.5 subsections for more information on these caller. See the rest of this sections subsections for more
options and option-specific structures. information on these options and option-specific structures.
sctp_opt_info() returns 0 on success, or on failure returns -1 and sctp_opt_info() returns 0 on success, or on failure returns -1 and
sets errno to the appropriate error code. sets errno to the appropriate error code.
All options that support specific settings on an association by 8.1. Read / Write Options
filling in either an association id variable or a sockaddr_storage
should also support the setting of the same value for the entire
endpoint (i.e. future associations). To accomplish this the
following logic is used when setting one of these options:
o If an address is specified via a sockaddr_storage that is included
in the structure, the address is used to lookup the association,
and the settings are applied to the specific address (if
appropriate) or to the entire association.
o If an association identification is filled in but not a
sockaddr_storage (if present), the association is found using the
association identification and the settings should be applied to
the specified association (since a specific address is not
specified). Note this also applies to options that hold an
association identification in their structure but do not have a
sockaddr_storage field.
o If neither the sockaddr_storage nor association identification is
set, i.e. the sockaddr_storage is set to all 0 (INADDR_ANY) and
the association identification is SCTP_FUTURE_ASSOC, the settings
are a default and to be applied to the endpoint.
7.1. Read / Write Options
7.1.1. Retransmission Timeout Parameters (SCTP_RTOINFO) 8.1.1. Retransmission Timeout Parameters (SCTP_RTOINFO)
The protocol parameters used to initialize and limit the The protocol parameters used to initialize and limit the
retransmission timeout (RTO) are tunable. See [RFC4960] for more retransmission timeout (RTO) are tunable. See [RFC4960] for more
information on how these parameters are used in RTO calculation. information on how these parameters are used in RTO calculation.
The following structure is used to access and modify these The following structure is used to access and modify these
parameters: parameters:
struct sctp_rtoinfo { struct sctp_rtoinfo {
sctp_assoc_t srto_assoc_id; sctp_assoc_t srto_assoc_id;
skipping to change at page 55, line 28 skipping to change at page 63, line 33
error to use SCTP_{CURRENT|ALL}_ASSOC in srto_assoc_id. error to use SCTP_{CURRENT|ALL}_ASSOC in srto_assoc_id.
All times are given in milliseconds. A value of 0, when modifying All times are given in milliseconds. A value of 0, when modifying
the parameters, indicates that the current value should not be the parameters, indicates that the current value should not be
changed. changed.
To access or modify these parameters, the application should call To access or modify these parameters, the application should call
getsockopt() or setsockopt() respectively with the option name getsockopt() or setsockopt() respectively with the option name
SCTP_RTOINFO. SCTP_RTOINFO.
7.1.2. Association Parameters (SCTP_ASSOCINFO) 8.1.2. Association Parameters (SCTP_ASSOCINFO)
This option is used to both examine and set various association and This option is used to both examine and set various association and
endpoint parameters. See [RFC4960] for more information on how this endpoint parameters. See [RFC4960] for more information on how this
parameter is used. parameter is used.
The following structure is used to access and modify these The following structure is used to access and modify these
parameters: parameters:
struct sctp_assocparams { struct sctp_assocparams {
sctp_assoc_t sasoc_assoc_id; sctp_assoc_t sasoc_assoc_id;
skipping to change at page 55, line 45 skipping to change at page 64, line 4
parameters: parameters:
struct sctp_assocparams { struct sctp_assocparams {
sctp_assoc_t sasoc_assoc_id; sctp_assoc_t sasoc_assoc_id;
uint16_t sasoc_asocmaxrxt; uint16_t sasoc_asocmaxrxt;
uint16_t sasoc_number_peer_destinations; uint16_t sasoc_number_peer_destinations;
uint32_t sasoc_peer_rwnd; uint32_t sasoc_peer_rwnd;
uint32_t sasoc_local_rwnd; uint32_t sasoc_local_rwnd;
uint32_t sasoc_cookie_life; uint32_t sasoc_cookie_life;
}; };
sasoc_assoc_id: This parameter is ignored for one-to-one style sasoc_assoc_id: This parameter is ignored for one-to-one style
sockets. For one-to-many style sockets the application may fill sockets. For one-to-many style sockets the application may fill
in an association identification or SCTP_FUTURE_ASSOC. It is an in an association identification or SCTP_FUTURE_ASSOC. It is an
error to use SCTP_{CURRENT|ALL}_ASSOC in sasoc_assoc_id. error to use SCTP_{CURRENT|ALL}_ASSOC in sasoc_assoc_id.
sasoc_asocmaxrxt: This contains the maximum retransmission attempts sasoc_asocmaxrxt: This contains the maximum retransmission attempts
to make for the association. to make for the association.
sasoc_number_peer_destinations: This is the number of destination sasoc_number_peer_destinations: This is the number of destination
addresses that the peer has. addresses that the peer has.
sasoc_peer_rwnd: This holds the current value of the peers rwnd sasoc_peer_rwnd: This holds the current value of the peers rwnd
(reported in the last SACK) minus any outstanding data (i.e. data (reported in the last SACK) minus any outstanding data (i.e. data
in flight). in flight).
sasoc_local_rwnd: This holds the last reported rwnd that was sent to sasoc_local_rwnd: This holds the last reported rwnd that was sent to
the peer. the peer.
sasoc_cookie_life: This is the association's cookie life value used sasoc_cookie_life: This is the association's cookie life value used
when issuing cookies. when issuing cookies.
The values of the sasoc_peer_rwnd is meaningless when examining The values of the sasoc_peer_rwnd is meaningless when examining
endpoint information. endpoint information (i.e. it is only valid when examining
information on a specific association).
All time values are given in milliseconds. A value of 0, when All time values are given in milliseconds. A value of 0, when
modifying the parameters, indicates that the current value should not modifying the parameters, indicates that the current value should not
be changed. be changed.
The values of the sasoc_asocmaxrxt and sasoc_cookie_life may be set The values of the sasoc_asocmaxrxt and sasoc_cookie_life may be set
on either an endpoint or association basis. The rwnd and destination on either an endpoint or association basis. The rwnd and destination
counts (sasoc_number_peer_destinations, sasoc_peer_rwnd, counts (sasoc_number_peer_destinations, sasoc_peer_rwnd,
sasoc_local_rwnd) are not settable and any value placed in these is sasoc_local_rwnd) are not settable and any value placed in these is
ignored. ignored.
skipping to change at page 56, line 45 skipping to change at page 65, line 6
unreachable is also tunable, but is address-specific, so it is unreachable is also tunable, but is address-specific, so it is
covered in a separate option. If an application attempts to set the covered in a separate option. If an application attempts to set the
value of the association maximum retransmission parameter to more value of the association maximum retransmission parameter to more
than the sum of all maximum retransmission parameters, setsockopt() than the sum of all maximum retransmission parameters, setsockopt()
may return an error. The reason for this, from [RFC4960] Section may return an error. The reason for this, from [RFC4960] Section
8.2: 8.2:
Note: When configuring the SCTP endpoint, the user should avoid Note: When configuring the SCTP endpoint, the user should avoid
having the value of 'Association.Max.Retrans' (sasoc_maxrxt in this having the value of 'Association.Max.Retrans' (sasoc_maxrxt in this
option) larger than the summation of the 'Path.Max.Retrans' (see option) larger than the summation of the 'Path.Max.Retrans' (see
Section 7.1.2 on spp_pathmaxrxt) of all the destination addresses for Section 8.1.2 on spp_pathmaxrxt) of all the destination addresses for
the remote endpoint. Otherwise, all the destination addresses may the remote endpoint. Otherwise, all the destination addresses may
become inactive while the endpoint still considers the peer endpoint become inactive while the endpoint still considers the peer endpoint
reachable. reachable.
7.1.3. Initialization Parameters (SCTP_INITMSG) 8.1.3. Initialization Parameters (SCTP_INITMSG)
Applications can specify protocol parameters for the default Applications can specify protocol parameters for the default
association initialization. The structure used to access and modify association initialization. The structure used to access and modify
these parameters is defined in Section 5.2.1. The option name these parameters is defined in Section 5.3.1. The option name
argument to setsockopt() and getsockopt() is SCTP_INITMSG. argument to setsockopt() and getsockopt() is SCTP_INITMSG.
Setting initialization parameters is effective only on an unconnected Setting initialization parameters is effective only on an unconnected
socket (for one-to-many style sockets only future associations are socket (for one-to-many style sockets only future associations are
affected by the change). With one-to-one style sockets, this option affected by the change).
is inherited by sockets derived from a listening socket.
7.1.4. SO_LINGER 8.1.4. SO_LINGER
An application can use this option to perform the SCTP ABORT An application can use this option to perform the SCTP ABORT
primitive. This option affects all associations related to the primitive. This option affects all associations related to the
socket. socket.
The linger option structure is: The linger option structure is:
struct linger { struct linger {
int l_onoff; /* option on/off */ int l_onoff; /* option on/off */
int l_linger; /* linger time */ int l_linger; /* linger time */
}; };
To enable the option, set l_onoff to 1. If the l_linger value is set To enable the option, set l_onoff to 1. If the l_linger value is set
to 0, calling close() is the same as the ABORT primitive. If the to 0, calling close() is the same as the ABORT primitive. If the
value is set to a negative value, the setsockopt() call will return value is set to a negative value, the setsockopt() call will return
an error. If the value is set to a positive value linger_time, the an error. If the value is set to a positive value linger_time, the
close() can be blocked for at most linger_time ms. If the graceful close() can be blocked for at most linger_time ms. If the graceful
shutdown phase does not finish during this period, close() will shutdown phase does not finish during this period, close() will
return but the graceful shutdown phase will continue in the system. return but the graceful shutdown phase will continue in the system.
Note, this is a socket level option not an SCTP level option. So Note, this is a socket level option, not an SCTP level option. When
when setting SO_LINGER an application must specify a level of using this option, an application must specify a level of SOL_SOCKET
SOL_SOCKET in the setsockopt() call. in the call.
7.1.5. SCTP_NODELAY 8.1.5. SCTP_NODELAY
Turn on/off any Nagle-like algorithm. This means that packets are Turn on/off any Nagle-like algorithm. This means that packets are
generally sent as soon as possible and no unnecessary delays are generally sent as soon as possible and no unnecessary delays are
introduced, at the cost of more packets in the network. Expects an introduced, at the cost of more packets in the network. Turning this
integer boolean flag. Turning this option on disables any Nagle-like option on disables any Nagle-like algorithm.
algorithm.
7.1.6. SO_RCVBUF This option expects an integer boolean flag, where a non-zero value
turns on the option, and a zero value turns off the option.
8.1.6. SO_RCVBUF
Sets the receive buffer size in octets. For SCTP one-to-one style Sets the receive buffer size in octets. For SCTP one-to-one style
sockets, this controls the receiver window size. For one-to-many sockets, this controls the receiver window size. For one-to-many
style sockets the meaning is implementation dependent. It might style sockets the meaning is implementation dependent. It might
control the receive buffer for each association bound to the socket control the receive buffer for each association bound to the socket
descriptor or it might control the receive buffer for the whole descriptor or it might control the receive buffer for the whole
socket. The call expects an integer. socket. This option expects an integer.
7.1.7. SO_SNDBUF Note, this is a socket level option, not an SCTP level option. When
using this option, an application must specify a level of SOL_SOCKET
in the call.
8.1.7. SO_SNDBUF
Sets the send buffer size. For SCTP one-to-one style sockets, this Sets the send buffer size. For SCTP one-to-one style sockets, this
controls the amount of data SCTP may have waiting in internal buffers controls the amount of data SCTP may have waiting in internal buffers
to be sent. This option therefore bounds the maximum size of data to be sent. This option therefore bounds the maximum size of data
that can be sent in a single send call. For one-to-many style that can be sent in a single send call. For one-to-many style
sockets, the effect is the same, except that it applies to one or all sockets, the effect is the same, except that it applies to one or all
associations (see Section 3.3) bound to the socket descriptor used in associations (see Section 3.3) bound to the socket descriptor used in
the setsockopt() or getsockopt() call. The option applies to each the setsockopt() or getsockopt() call. The option applies to each
association's window size separately. The call expects an integer. association's window size separately. This option expects an
integer.
7.1.8. Automatic Close of Associations (SCTP_AUTOCLOSE) Note, this is a socket level option, not an SCTP level option. When
using this option, an application must specify a level of SOL_SOCKET
in the call.
8.1.8. Automatic Close of Associations (SCTP_AUTOCLOSE)
This socket option is applicable to the one-to-many style socket This socket option is applicable to the one-to-many style socket
only. When set it will cause associations that are idle for more only. When set it will cause associations that are idle for more
than the specified number of seconds to automatically close using the than the specified number of seconds to automatically close using the
graceful shutdown procedure. An association being idle is defined as graceful shutdown procedure. An association being idle is defined as
an association that has not sent or received user data. The special an association that has not sent or received user data. The special
value of '0' indicates that no automatic close of any association value of '0' indicates that no automatic close of any association
should be performed, this is the default value. The option expects should be performed, this is the default value. This option expects
an integer defining the number of seconds of idle time before an an integer defining the number of seconds of idle time before an
association is closed. association is closed.
An application using this option should enable receiving the An application using this option should enable receiving the
association change notification. This is the only mechanism an association change notification. This is the only mechanism an
application is informed about the closing of an association. After application is informed about the closing of an association. After
an association is closed, the association ID assigned to it can be an association is closed, the association ID assigned to it can be
reused. An application should be aware of this to avoid the possible reused. An application should be aware of this to avoid the possible
problem of sending data to an incorrect peer endpoint. problem of sending data to an incorrect peer endpoint.
7.1.9. Set Primary Address (SCTP_PRIMARY_ADDR) 8.1.9. Set Primary Address (SCTP_PRIMARY_ADDR)
Requests that the local SCTP stack uses the enclosed peer address as Requests that the local SCTP stack uses the enclosed peer address as
the association's primary. The enclosed address must be one of the the association's primary. The enclosed address must be one of the
association peer's addresses. association peer's addresses.
The following structure is used to make a set peer primary request: The following structure is used to make a set peer primary request:
struct sctp_setprim { struct sctp_setprim {
sctp_assoc_t ssp_assoc_id; sctp_assoc_t ssp_assoc_id;
struct sockaddr_storage ssp_addr; struct sockaddr_storage ssp_addr;
skipping to change at page 59, line 12 skipping to change at page 67, line 24
The following structure is used to make a set peer primary request: The following structure is used to make a set peer primary request:
struct sctp_setprim { struct sctp_setprim {
sctp_assoc_t ssp_assoc_id; sctp_assoc_t ssp_assoc_id;
struct sockaddr_storage ssp_addr; struct sockaddr_storage ssp_addr;
}; };
ssp_addr: The address to set as primary. No wildcard address is ssp_addr: The address to set as primary. No wildcard address is
allowed. allowed.
ssp_assoc_id: This parameter is ignored for one-to-one style ssp_assoc_id: This parameter is ignored for one-to-one style
sockets. For one-to-many style sockets it identifies the sockets. For one-to-many style sockets it identifies the
association for this request. Note that the special sctp_assoc_t association for this request. Note that the special sctp_assoc_t
SCTP_{FUTURE|ALL|CURRENT}_ASSOC are not allowed. SCTP_{FUTURE|ALL|CURRENT}_ASSOC are not allowed.
7.1.10. Set Adaptation Layer Indicator (SCTP_ADAPTATION_LAYER) 8.1.10. Set Adaptation Layer Indicator (SCTP_ADAPTATION_LAYER)
Requests that the local endpoint set the specified Adaptation Layer Requests that the local endpoint set the specified Adaptation Layer
Indication parameter for all future INIT and INIT-ACK exchanges. Indication parameter for all future INIT and INIT-ACK exchanges.
The following structure is used to access and modify this parameter: The following structure is used to access and modify this parameter:
struct sctp_setadaptation { struct sctp_setadaptation {
uint32_t ssb_adaptation_ind; uint32_t ssb_adaptation_ind;
}; };
ssb_adaptation_ind: The adaptation layer indicator that will be ssb_adaptation_ind: The adaptation layer indicator that will be
included in any outgoing Adaptation Layer Indication parameter. included in any outgoing Adaptation Layer Indication parameter.
7.1.11. Enable/Disable Message Fragmentation (SCTP_DISABLE_FRAGMENTS) 8.1.11. Enable/Disable Message Fragmentation (SCTP_DISABLE_FRAGMENTS)
This option is a on/off flag and is passed as an integer where a non- This option is a on/off flag and is passed as an integer where a non-
zero is on and a zero is off. If enabled no SCTP message zero is on and a zero is off. If enabled no SCTP message
fragmentation will be performed. If disabled, if a message being fragmentation will be performed. The effect of enabling this option
sent exceeds the current PMTU size, the message will not be sent and are that if a message being sent exceeds the current PMTU size, the
instead an error will be indicated to the user. message will not be sent and instead an error will be indicated to
the user. If this option is disabled (the default) then a message
exceeding the size of the PMTU will be fragmented and reassembled by
the peer.
7.1.12. Peer Address Parameters (SCTP_PEER_ADDR_PARAMS) 8.1.12. Peer Address Parameters (SCTP_PEER_ADDR_PARAMS)
Applications can enable or disable heartbeats for any peer address of Applications can enable or disable heartbeats for any peer address of
an association, modify an address's heartbeat interval, force a an association, modify an address's heartbeat interval, force a
heartbeat to be sent immediately, and adjust the address's maximum heartbeat to be sent immediately, and adjust the address's maximum
number of retransmissions sent before an address is considered number of retransmissions sent before an address is considered
unreachable. unreachable.
The following structure is used to access and modify an address's The following structure is used to access and modify an address's
parameters: parameters:
skipping to change at page 60, line 20 skipping to change at page 68, line 33
uint32_t spp_pathmtu; uint32_t spp_pathmtu;
uint32_t spp_flags; uint32_t spp_flags;
uint32_t spp_ipv6_flowlabel; uint32_t spp_ipv6_flowlabel;
uint8_t spp_ipv4_tos; uint8_t spp_ipv4_tos;
}; };
spp_assoc_id: This parameter is ignored for one-to-one style spp_assoc_id: This parameter is ignored for one-to-one style
sockets. For one-to-many style sockets it identifies the sockets. For one-to-many style sockets it identifies the
association for this query. Note that the predefined constants association for this query. Note that the predefined constants
are not allowed. are not allowed.
spp_address: This specifies which address is of interest. If a spp_address: This specifies which address is of interest. If a
wildcard address is provided it applies to all current and future wildcard address is provided it applies to all current and future
paths. paths.
spp_hbinterval: This contains the value of the heartbeat interval, spp_hbinterval: This contains the value of the heartbeat interval,
in milliseconds (HB.Interval in [RFC4960]). Note that unless the in milliseconds (HB.Interval in [RFC4960]). Note that unless the
spp_flag is set to SPP_HB_ENABLE the value of this field is spp_flag is set to SPP_HB_ENABLE the value of this field is
ignored. Note also that a value of zero indicates the current ignored. Note also that a value of zero indicates the current
setting should be left unchanged. To set an actual value of zero setting should be left unchanged. To set an actual value of zero
the use of the flag SPP_HB_TIME_IS_ZERO should be used. Even when the use of the flag SPP_HB_TIME_IS_ZERO should be used. Even when
it is set to 0, it does not mean that SCTP will continuously send it is set to 0, it does not mean that SCTP will continuously send
out heartbeat since the actual interval also includes the current out heartbeat since the actual interval also includes the current
RTO and jitter (see Section 8.3 in [RFC4960]). RTO and jitter (see Section 8.3 in [RFC4960]).
spp_pathmaxrxt: This contains the maximum number of retransmissions spp_pathmaxrxt: This contains the maximum number of retransmissions
before this address shall be considered unreachable. Note that a before this address shall be considered unreachable. Note that a
value of zero indicates the current setting should be left value of zero indicates the current setting should be left
unchanged. unchanged.
spp_pathmtu: The current path MTU of the peer address. It is the
number of bytes available in an SCTP packet for chunks. Providing
a value of 0 does not change the current setting. If a positive
value is provided and SPP_PMTUD_DISABLE is set in the spp_flags,
the given value is used as the path MTU. If SPP_PMTUD_ENABLE is
set in the spp_flags, the spp_pathmtu field is ignored.
spp_ipv6_flowlabel: This field is used in conjunction with the spp_ipv6_flowlabel: This field is used in conjunction with the
SPP_IPV6_FLOWLABEL flag. This setting has precedence over any SPP_IPV6_FLOWLABEL flag. This setting has precedence over any
IPv6 layer setting. IPv6 layer setting.
spp_ipv4_tos: This field is used in conjunction with the spp_ipv4_tos: This field is used in conjunction with the
SPP_IPV4_TOS flag. This setting has precedence over any IPv4 SPP_IPV4_TOS flag. This setting has precedence over any IPv4
layer setting. layer setting.
spp_flags: These flags are used to control various features on an spp_flags: These flags are used to control various features on an
association. The flag field is a bit mask which may contain zero association. The flag field is a bit mask which may contain zero
or more of the following options: or more of the following options:
SPP_HB_ENABLE: Enable heartbeats on the specified address. SPP_HB_ENABLE: Enable heartbeats on the specified address.
SPP_HB_DISABLE: Disable heartbeats on the specified address. SPP_HB_DISABLE: Disable heartbeats on the specified address.
Note that SPP_HB_ENABLE and SPP_HB_DISABLE are mutually Note that SPP_HB_ENABLE and SPP_HB_DISABLE are mutually
exclusive, only one of these two should be specified. Enabling exclusive, only one of these two should be specified. Enabling
both fields will have undetermined results. both fields will have undetermined results.
SPP_HB_DEMAND: Request a user initiated heartbeat to be made SPP_HB_DEMAND: Request a user initiated heartbeat to be made
immediately. This must not be used in conjunction with a immediately. This must not be used in conjunction with a
wildcard address. wildcard address.
SPP_HB_TIME_IS_ZERO: Specifies that the time for heartbeat delay SPP_HB_TIME_IS_ZERO: Specifies that the time for heartbeat delay
is to be set to the value of 0 milliseconds. is to be set to the value of 0 milliseconds.
SPP_PMTUD_ENABLE: This field will enable PMTU discovery upon the SPP_PMTUD_ENABLE: This field will enable PMTU discovery upon the
specified address. specified address.
SPP_PMTUD_DISABLE: This field will disable PMTU discovery upon SPP_PMTUD_DISABLE: This field will disable PMTU discovery upon
the specified address. Note that if the address field is empty the specified address. Note that if the address field is empty
then all addresses on the association are affected. Note also then all addresses on the association are affected. Note also
that SPP_PMTUD_ENABLE and SPP_PMTUD_DISABLE are mutually that SPP_PMTUD_ENABLE and SPP_PMTUD_DISABLE are mutually
exclusive. Enabling both will have undetermined results. exclusive. Enabling both will have undetermined results.
SPP_IPV6_FLOWLABEL: Setting this flag enables the setting of the SPP_IPV6_FLOWLABEL: Setting this flag enables the setting of the
IPV6 flowlabel value. The value is obtained in the IPV6 flowlabel value. The value is obtained in the
spp_ipv6_flowlabel field. spp_ipv6_flowlabel field.
Upon retrieval, this flag will be set to indicate that the Upon retrieval, this flag will be set to indicate that the
spp_ipv6_flowlabel field has a valid value returned. If a spp_ipv6_flowlabel field has a valid value returned. If a
specific destination address is set (in the spp_address field), specific destination address is set (in the spp_address field),
then the value returned is that of the address. If just an then the value returned is that of the address. If just an
association is specified (and no address), then the association is specified (and no address), then the
association's default flowlabel is returned. If neither an association's default flowlabel is returned. If neither an
skipping to change at page 61, line 46 skipping to change at page 70, line 28
destination address is set when called (in the spp_address destination address is set when called (in the spp_address
field) then that specific destination address' TOS value is field) then that specific destination address' TOS value is
returned. If just an association is specified then the returned. If just an association is specified then the
association default TOS is returned. If neither an association association default TOS is returned. If neither an association
nor a destination is specified, then the sockets default TOS is nor a destination is specified, then the sockets default TOS is
returned. returned.
To read or modify these parameters, the application should call To read or modify these parameters, the application should call
sctp_opt_info() with the SCTP_PEER_ADDR_PARAMS option. sctp_opt_info() with the SCTP_PEER_ADDR_PARAMS option.
7.1.13. Set Default Send Parameters (SCTP_DEFAULT_SEND_PARAM) 8.1.13. Set Default Send Parameters (SCTP_DEFAULT_SEND_PARAM) -
DEPRECATED
Please note that this options is deprecated. Section 7.1.31 should Please note that this options is deprecated. Section 8.1.31 should
be used instead. be used instead.
Applications that wish to use the sendto() system call may wish to Applications that wish to use the sendto() system call may wish to
specify a default set of parameters that would normally be supplied specify a default set of parameters that would normally be supplied
through the inclusion of ancillary data. This socket option allows through the inclusion of ancillary data. This socket option allows
such an application to set the default sctp_sndrcvinfo structure. such an application to set the default sctp_sndrcvinfo structure.
The application that wishes to use this socket option simply passes The application that wishes to use this socket option simply passes
the sctp_sndrcvinfo structure defined in Section 5.2.2 to this call. the sctp_sndrcvinfo structure defined in Section 5.3.2 to this call.
The input parameters accepted by this call include sinfo_stream, The input parameters accepted by this call include sinfo_stream,
sinfo_flags, sinfo_ppid, sinfo_context, sinfo_pr_policy and sinfo_flags, sinfo_ppid, sinfo_context, and sinfo_timetolive. The
sinfo_pr_value. The sinfo_flags is composed of a bitwise OR of sinfo_flags is composed of a bitwise OR of SCTP_UNORDERED, SCTP_EOF,
SCTP_UNORDERED, SCTP_EOF, and SCTP_SENDALL. The sinfo_assoc_id field and SCTP_SENDALL. The sinfo_assoc_id field specifies the association
specifies the association to apply the parameters to. For a one-to- to apply the parameters to. For a one-to-many style socket any of
many style socket any of the predefined constants are also allowed in the predefined constants are also allowed in this field. The field
this field. The field is ignored on the one-to-one style. is ignored on the one-to-one style.
7.1.14. Set Notification and Ancillary Events (SCTP_EVENTS) 8.1.14. Set Notification and Ancillary Events (SCTP_EVENTS) -
DEPRECATED
This socket option is used to specify various notifications and This socket option is used to specify various notifications and
ancillary data the user wishes to receive. Please see Section 7.4 ancillary data the user wishes to receive. Please see Section 6.2.1
for a full description of this option and its usage. Note that this for a full description of this option and its usage. Note that this
option is considered deprecated and present for backward option is considered deprecated and present for backward
compatibility. New applications should use the SCTP_SET_EVENT compatibility. New applications should use the SCTP_EVENT option.
option. See Section 7.4 for a full description of that option as See Section 6.2.2 for a full description of that option as well.
well.
7.1.15. Set/Clear IPv4 Mapped Addresses (SCTP_I_WANT_MAPPED_V4_ADDR) 8.1.15. Set/Clear IPv4 Mapped Addresses (SCTP_I_WANT_MAPPED_V4_ADDR)
This socket option is a boolean flag which turns on or off the This socket option is a boolean flag which turns on or off the
mapping of IPv4 addresses. If this option is turned on, then IPv4 mapping of IPv4 addresses. If this option is turned on, then IPv4
addresses will be mapped to V6 representation. If this option is addresses will be mapped to V6 representation. If this option is
turned off, then no mapping will be done of V4 addresses and a user turned off, then no mapping will be done of V4 addresses and a user
will receive both PF_INET6 and PF_INET type addresses on the socket. will receive both PF_INET6 and PF_INET type addresses on the socket.
See [RFC3542] for more details on mapped V6 addresses. See [RFC3542] for more details on mapped V6 addresses.
If this socket option is used on a socket of type PF_INET an error is If this socket option is used on a socket of type PF_INET an error is
returned. returned.
By default this option is turned off and expects an integer to be By default this option is turned off and expects an integer to be
passed where non-zero turns on the option and zero turns off the passed where a non-zero value turns on the option and a zero value
option. turns off the option.
7.1.16. Get or Set the Maximum Fragmentation Size (SCTP_MAXSEG) 8.1.16. Get or Set the Maximum Fragmentation Size (SCTP_MAXSEG)
This option will get or set the maximum size to put in any outgoing This option will get or set the maximum size to put in any outgoing
SCTP DATA chunk. If a message is larger than this size it will be SCTP DATA chunk. If a message is larger than this size it will be
fragmented by SCTP into the specified size. Note that the underlying fragmented by SCTP into the specified size. Note that the underlying
SCTP implementation may fragment into smaller sized chunks when the SCTP implementation may fragment into smaller sized chunks when the
PMTU of the underlying association is smaller than the value set by PMTU of the underlying association is smaller than the value set by
the user. The default value for this option is '0' which indicates the user. The default value for this option is '0' which indicates
the user is not limiting fragmentation and only the PMTU will affect the user is not limiting fragmentation and only the PMTU will affect
SCTP's choice of DATA chunk size. Note also that values set larger SCTP's choice of DATA chunk size. Note also that values set larger
than the maximum size of an IP datagram will effectively let SCTP than the maximum size of an IP datagram will effectively let SCTP
skipping to change at page 63, line 18 skipping to change at page 72, line 4
struct sctp_assoc_value { struct sctp_assoc_value {
sctp_assoc_t assoc_id; sctp_assoc_t assoc_id;
uint32_t assoc_value; uint32_t assoc_value;
}; };
assoc_id: This parameter is ignored for one-to-one style sockets. assoc_id: This parameter is ignored for one-to-one style sockets.
For one-to-many style sockets this parameter indicates which For one-to-many style sockets this parameter indicates which
association the user is performing an action upon. It is an error association the user is performing an action upon. It is an error
to use SCTP_{CURRENT|ALL}_ASSOC in assoc_id. to use SCTP_{CURRENT|ALL}_ASSOC in assoc_id.
assoc_value: This parameter specifies the maximum size in bytes. assoc_value: This parameter specifies the maximum size in bytes.
7.1.17. Get or Set the List of Supported HMAC Identifiers 8.1.17. Get or Set the List of Supported HMAC Identifiers
(SCTP_HMAC_IDENT) (SCTP_HMAC_IDENT)
This option gets or sets the list of HMAC algorithms that the local This option gets or sets the list of HMAC algorithms that the local
endpoint requires the peer to use. endpoint requires the peer to use.
The following structure is used to get or set these identifiers: The following structure is used to get or set these identifiers:
struct sctp_hmacalgo { struct sctp_hmacalgo {
uint32_t shmac_number_of_idents; uint32_t shmac_number_of_idents;
uint16_t shmac_idents[]; uint16_t shmac_idents[];
skipping to change at page 64, line 5 skipping to change at page 72, line 39
* SCTP_AUTH_HMAC_ID_SHA256 * SCTP_AUTH_HMAC_ID_SHA256
Note that the list supplied must include SCTP_AUTH_HMAC_ID_SHA1 and Note that the list supplied must include SCTP_AUTH_HMAC_ID_SHA1 and
may include any of the other values in its preferred order (lowest may include any of the other values in its preferred order (lowest
list position has the highest preference in algorithm selection). list position has the highest preference in algorithm selection).
Note also that the lack of SCTP_AUTH_HMAC_ID_SHA1, or the inclusion Note also that the lack of SCTP_AUTH_HMAC_ID_SHA1, or the inclusion
of an unknown HMAC identifier (including optional identifiers unknown of an unknown HMAC identifier (including optional identifiers unknown
to the implementation) will cause the set option to fail and return to the implementation) will cause the set option to fail and return
an error. an error.
7.1.18. Get or Set the Active Shared Key (SCTP_AUTH_ACTIVE_KEY) 8.1.18. Get or Set the Active Shared Key (SCTP_AUTH_ACTIVE_KEY)
This option will get or set the active shared key to be used to build This option will get or set the active shared key to be used to build
the association shared key. the association shared key.
The following structure is used to access and modify these The following structure is used to access and modify these
parameters: parameters:
struct sctp_authkeyid { struct sctp_authkeyid {
sctp_assoc_t scact_assoc_id; sctp_assoc_t scact_assoc_id;
uint16_t scact_keynumber; uint16_t scact_keynumber;
skipping to change at page 64, line 39 skipping to change at page 73, line 26
When used with setsockopt() the SCTP implementation must use the When used with setsockopt() the SCTP implementation must use the
indicated shared key identifier for all messages being given to an indicated shared key identifier for all messages being given to an
SCTP implementation via a send call after the setsockopt() call until SCTP implementation via a send call after the setsockopt() call until
changed again. Therefore, the SCTP implementation must not bundle changed again. Therefore, the SCTP implementation must not bundle
user messages which should be authenticated using different shared user messages which should be authenticated using different shared
key identifiers. key identifiers.
Initially the key with key identifier 0 is the active key. Initially the key with key identifier 0 is the active key.
7.1.19. Get or Set Delayed SACK Timer (SCTP_DELAYED_SACK) 8.1.19. Get or Set Delayed SACK Timer (SCTP_DELAYED_SACK)
This option will affect the way delayed sacks are performed. This This option will affect the way delayed sacks are performed. This
option allows the application to get or set the delayed sack time, in option allows the application to get or set the delayed sack time, in
milliseconds. It also allows changing the delayed sack frequency. milliseconds. It also allows changing the delayed sack frequency.
Changing the frequency to 1 disables the delayed sack algorithm. Changing the frequency to 1 disables the delayed sack algorithm.
Note that if sack_delay or sack_freq are 0 when setting this option, Note that if sack_delay or sack_freq are 0 when setting this option,
the current values will remain unchanged. the current values will remain unchanged.
The following structure is used to access and modify these The following structure is used to access and modify these
parameters: parameters:
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struct sctp_sack_info { struct sctp_sack_info {
sctp_assoc_t sack_assoc_id; sctp_assoc_t sack_assoc_id;
uint32_t sack_delay; uint32_t sack_delay;
uint32_t sack_freq; uint32_t sack_freq;
}; };
sack_assoc_id: This parameter is ignored for one-to-one style sack_assoc_id: This parameter is ignored for one-to-one style
sockets. For one-to-many style sockets this parameter indicates sockets. For one-to-many style sockets this parameter indicates
which association the user is performing an action upon. The which association the user is performing an action upon. The
special SCTP_{FUTURE|CURRENT|ALL}_ASSOC can also be used. special SCTP_{FUTURE|CURRENT|ALL}_ASSOC can also be used.
sack_delay: This parameter contains the number of milliseconds that sack_delay: This parameter contains the number of milliseconds that
the user is requesting the delayed SACK timer to be set to. Note the user is requesting the delayed SACK timer to be set to. Note
that this value is defined in the standard to be between 200 and that this value is defined in the standard to be between 200 and
500 milliseconds. 500 milliseconds.
sack_freq: This parameter contains the number of packets that must sack_freq: This parameter contains the number of packets that must
be received before a sack is sent without waiting for the delay be received before a sack is sent without waiting for the delay
timer to expire. The default value is 2, setting this value to 1 timer to expire. The default value is 2, setting this value to 1
will disable the delayed sack algorithm. will disable the delayed sack algorithm.
7.1.20. Get or Set Fragmented Interleave (SCTP_FRAGMENT_INTERLEAVE) 8.1.20. Get or Set Fragmented Interleave (SCTP_FRAGMENT_INTERLEAVE)
Fragmented interleave controls how the presentation of messages Fragmented interleave controls how the presentation of messages
occurs for the message receiver. There are three levels of fragment occurs for the message receiver. There are three levels of fragment
interleave defined. Two of the levels affect the one-to-one model, interleave defined. Two of the levels affect the one-to-one model,
while the one-to-many model is affected by all three levels. while the one-to-many model is affected by all three levels.
This option takes an integer value. It can be set to a value of 0, 1 This option takes an integer value. It can be set to a value of 0, 1
or 2. Attempting to set this level to other values will return an or 2. Attempting to set this level to other values will return an
error. error.
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receive, some other association's message may be delivered upon receive, some other association's message may be delivered upon
the next receive. the next receive.
An implementation should default the one-to-many model to level 1. An implementation should default the one-to-many model to level 1.
The reason for this is that otherwise it is possible that a peer The reason for this is that otherwise it is possible that a peer
could begin sending a partial message and thus block all other peers could begin sending a partial message and thus block all other peers
from sending data. However a setting of level 2 requires the from sending data. However a setting of level 2 requires the
application to not only be aware of the association (via the application to not only be aware of the association (via the
association id or peer's address) but also the stream number. The association id or peer's address) but also the stream number. The
stream number is not present unless the user has subscribed to the stream number is not present unless the user has subscribed to the
sctp_data_io_events (see Section 7.4). This is also why we recommend sctp_data_io_events (see Section 6.2). This is also why we recommend
that the one-to-one model be defaulted to level 0 (level 1 for the that the one-to-one model be defaulted to level 0 (level 1 for the
one-to-one model has no effect). Note that an implementation should one-to-one model has no effect). Note that an implementation should
return an error if an application attempts to set the level to 2 and return an error if an application attempts to set the level to 2 and
has not subscribed to the sctp_data_io_events. has not subscribed to the sctp_data_io_events.
For applications that have subscribed to events those events appear For applications that have subscribed to events, those events appear
in the normal socket buffer data stream. This means that unless the in the normal socket buffer data stream. This means that unless the
user has set the fragmentation interleave level to 0, notifications user has set the fragmentation interleave level to 0, notifications
may also be interleaved with partially delivered messages. may also be interleaved with partially delivered messages.
7.1.21. Set or Get the SCTP Partial Delivery Point 8.1.21. Set or Get the SCTP Partial Delivery Point
(SCTP_PARTIAL_DELIVERY_POINT) (SCTP_PARTIAL_DELIVERY_POINT)
This option will set or get the SCTP partial delivery point. This This option will set or get the SCTP partial delivery point. This
point is the size of a message where the partial delivery API will be point is the size of a message where the partial delivery API will be
invoked to help free up rwnd space for the peer. Setting this to a invoked to help free up rwnd space for the peer. Setting this to a
lower value will cause partial deliveries to happen more often. The lower value will cause partial deliveries to happen more often. This
call's argument is an integer that sets or gets the partial delivery option expects an integer that sets or gets the partial delivery
point in bytes. Note also that the call will fail if the user point in bytes. Note also that the call will fail if the user
attempts to set this value larger than the socket receive buffer attempts to set this value larger than the socket receive buffer
size. size.
Note that any single message having a length smaller than or equal to Note that any single message having a length smaller than or equal to
the SCTP partial delivery point will be delivered in one single read the SCTP partial delivery point will be delivered in one single read
call as long as the user provided buffer is large enough to hold the call as long as the user provided buffer is large enough to hold the
message. message.
7.1.22. Set or Get the Use of Extended Receive Info 8.1.22. Set or Get the Use of Extended Receive Info
(SCTP_USE_EXT_RCVINFO) (SCTP_USE_EXT_RCVINFO) - DEPRECATED
This option will enable or disable the use of the extended version of This option will enable or disable the use of the extended version of
the sctp_sndrcvinfo structure. If this option is disabled, then the the sctp_sndrcvinfo structure. If this option is disabled, then the
normal sctp_sndrcvinfo structure is returned in all receive message normal sctp_sndrcvinfo structure is returned in all receive message
calls. If this option is enabled then the sctp_extrcvinfo structure calls. If this option is enabled then the sctp_extrcvinfo structure
is returned in all receive message calls. The default is off. is returned in all receive message calls. The default is off.
Note that the sctp_extrcvinfo structure is never used in any send Note that the sctp_extrcvinfo structure is never used in any send
call. call.
This option is present for compatibility with older applications and This option is present for compatibility with older applications and
is deprecated. Future applications should use SCTP_NXTINFO to is deprecated. Future applications should use SCTP_NXTINFO to
retrieve this same information via ancillary data. retrieve this same information via ancillary data.
7.1.23. Set or Get the Auto ASCONF Flag (SCTP_AUTO_ASCONF) 8.1.23. Set or Get the Auto ASCONF Flag (SCTP_AUTO_ASCONF)
This option will enable or disable the use of the automatic This option will enable or disable the use of the automatic
generation of ASCONF chunks to add and delete addresses to an generation of ASCONF chunks to add and delete addresses to an
existing association. Note that this option has two caveats namely: existing association. Note that this option has two caveats namely:
a) it only affects sockets that are bound to all addresses on the a) it only affects sockets that are bound to all addresses available
machine, and b) the system administrator may have an overriding to the SCTP stack, and b) the system administrator may have an
control that turns the ASCONF feature off no matter what setting the overriding control that turns the ASCONF feature off no matter what
socket option may have. setting the socket option may have.
7.1.24. Set or Get the Maximum Burst (SCTP_MAX_BURST) This option expects an integer boolean flag, where a non-zero value
turns on the option, and a zero value turns off the option.
8.1.24. Set or Get the Maximum Burst (SCTP_MAX_BURST)
This option will allow a user to change the maximum burst of packets This option will allow a user to change the maximum burst of packets
that can be emitted by this association. Note that the default value that can be emitted by this association. Note that the default value
is 4, and some implementations may restrict this setting so that it is 4, and some implementations may restrict this setting so that it
can only be lowered to positive values. can only be lowered to positive values.
To set or get this option the user fills in the following structure: To set or get this option the user fills in the following structure:
struct sctp_assoc_value { struct sctp_assoc_value {
sctp_assoc_t assoc_id; sctp_assoc_t assoc_id;
skipping to change at page 68, line 8 skipping to change at page 77, line 5
}; };
assoc_id: This parameter is ignored for one-to-one style sockets. assoc_id: This parameter is ignored for one-to-one style sockets.
For one-to-many style sockets this parameter indicates which For one-to-many style sockets this parameter indicates which
association the user is performing an action upon. The special association the user is performing an action upon. The special
SCTP_{FUTURE|CURRENT|ALL}_ASSOC can also be used. SCTP_{FUTURE|CURRENT|ALL}_ASSOC can also be used.
assoc_value: This parameter contains the maximum burst. Setting the assoc_value: This parameter contains the maximum burst. Setting the
value to 0 disables burst mitigation. value to 0 disables burst mitigation.
7.1.25. Set or Get the Default Context (SCTP_CONTEXT) 8.1.25. Set or Get the Default Context (SCTP_CONTEXT)
The context field in the sctp_sndrcvinfo structure is normally only The context field in the sctp_sndrcvinfo structure is normally only
used when a failed message is retrieved holding the value that was used when a failed message is retrieved holding the value that was
sent down on the actual send call. This option allows the setting of sent down on the actual send call. This option allows the setting of
a default context on an association basis that will be received on a default context on an association basis that will be received on
reading messages from the peer. This is especially helpful in the reading messages from the peer. This is especially helpful in the
one-to-many model for an application to keep some reference to an one-to-many model for an application to keep some reference to an
internal state machine that is processing messages on the internal state machine that is processing messages on the
association. Note that the setting of this value only affects association. Note that the setting of this value only affects
received messages from the peer and does not affect the value that is received messages from the peer and does not affect the value that is
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struct sctp_assoc_value { struct sctp_assoc_value {
sctp_assoc_t assoc_id; sctp_assoc_t assoc_id;
uint32_t assoc_value; uint32_t assoc_value;
}; };
assoc_id: This parameter is ignored for one-to-one style sockets. assoc_id: This parameter is ignored for one-to-one style sockets.
For one-to-many style sockets this parameter indicates which For one-to-many style sockets this parameter indicates which
association the user is performing an action upon. The special association the user is performing an action upon. The special
SCTP_{FUTURE|CURRENT|ALL}_ASSOC can also be used. SCTP_{FUTURE|CURRENT|ALL}_ASSOC can also be used.
assoc_value: This parameter contains the context. assoc_value: This parameter contains the context.
7.1.26. Enable or Disable Explicit EOR Marking (SCTP_EXPLICIT_EOR) 8.1.26. Enable or Disable Explicit EOR Marking (SCTP_EXPLICIT_EOR)
This boolean flag is used to enable or disable explicit end of record This boolean flag is used to enable or disable explicit end of record
(EOR) marking. When this option is enabled, a user may make multiple (EOR) marking. When this option is enabled, a user may make multiple
send system calls to send a record and must indicate that they are send system calls to send a record and must indicate that they are
finished sending a particular record by including the SCTP_EOR flag. finished sending a particular record by including the SCTP_EOR flag.
If this boolean flag is disabled then each individual send system If this boolean flag is disabled then each individual send system
call is considered to have an SCTP_EOR indicator set on it implicitly call is considered to have an SCTP_EOR indicator set on it implicitly
without the user having to explicitly add this flag. The default is without the user having to explicitly add this flag. The default is
off. off.
7.1.27. Enable SCTP Port Reusage (SCTP_REUSE_PORT) This option expects an integer boolean flag, where a non-zero value
turns on the option, and a zero value turns off the option.
8.1.27. Enable SCTP Port Reusage (SCTP_REUSE_PORT)
This option only supports one-to-one style SCTP sockets. If used on This option only supports one-to-one style SCTP sockets. If used on
a one-to-many style SCTP socket an error is indicated. a one-to-many style SCTP socket an error is indicated.
This setsockopt() call must not be used after calling bind() or This option expects an integer boolean flag, where a non-zero value
turns on the option, and a zero value turns off the option.
This socket option must not be used after calling bind() or
sctp_bindx() for a one-to-one style SCTP socket. If using bind() or sctp_bindx() for a one-to-one style SCTP socket. If using bind() or
sctp_bindx() on a socket with the SCTP_REUSE_PORT option, all other sctp_bindx() on a socket with the SCTP_REUSE_PORT option, all other
SCTP sockets bound to the same port must have set the SCTP sockets bound to the same port must have set the
SCTP_REUSE_PORT. Calling bind() or sctp_bindx() for a socket without SCTP_REUSE_PORT. Calling bind() or sctp_bindx() for a socket without
having set the SCTP_REUSE_PORT option will fail if there are other having set the SCTP_REUSE_PORT option will fail if there are other
sockets bound to the same port. At most one socket being bound to sockets bound to the same port. At most one socket being bound to
the same port may be listening. the same port may be listening.
It should be noted that the behavior of the socket level socket It should be noted that the behavior of the socket level socket
option to reuse ports and/or addresses for SCTP sockets is option to reuse ports and/or addresses for SCTP sockets is
unspecified. unspecified.
7.1.28. Set Notification Event (SCTP_EVENT) 8.1.28. Set Notification Event (SCTP_EVENT)
This socket option is used to set a specific notification option. This socket option is used to set a specific notification option.
Please see Section 7.4 for a full description of this option and its Please see Section 6.2.2 for a full description of this option and
usage. its usage.
7.1.29. Enable or Disable the Delivery of SCTP_RCVINFO as Ancillary 8.1.29. Enable or Disable the Delivery of SCTP_RCVINFO as Ancillary
Data (SCTP_RECVRCVINFO) Data (SCTP_RECVRCVINFO)
Setting this option specifies that SCTP_RCVINFO defined in Setting this option specifies that SCTP_RCVINFO defined in
Section 5.2.5 is returned as ancillary data by recvmsg(). The call Section 5.3.5 is returned as ancillary data by recvmsg().
expects an integer.
7.1.30. Enable or Disable the Delivery of SCTP_NXTINFO as Ancillary This option expects an integer boolean flag, where a non-zero value
turns on the option, and a zero value turns off the option.
8.1.30. Enable or Disable the Delivery of SCTP_NXTINFO as Ancillary
Data (SCTP_RECVNXTINFO) Data (SCTP_RECVNXTINFO)
Setting this option specifies that SCTP_NXTINFO defined in Setting this option specifies that SCTP_NXTINFO defined in
Section 5.2.6 is returned as ancillary data by recvmsg(). The call Section 5.3.6 is returned as ancillary data by recvmsg().
expects an integer.
7.1.31. Set Default Send Parameters (SCTP_DEFAULT_SNDINFO) This option expects an integer boolean flag, where a non-zero value
turns on the option, and a zero value turns off the option.
8.1.31. Set Default Send Parameters (SCTP_DEFAULT_SNDINFO)
Applications that wish to use the sendto() system call may wish to Applications that wish to use the sendto() system call may wish to
specify a default set of parameters that would normally be supplied specify a default set of parameters that would normally be supplied
through the inclusion of ancillary data. This socket option allows through the inclusion of ancillary data. This socket option allows
such an application to set the default sctp_sndrcvinfo structure. such an application to set the default sctp_sndinfo structure. The
The application that wishes to use this socket option simply passes application that wishes to use this socket option simply passes the
the sctp_sndinfo structure defined in Section 5.2.4 to this call. sctp_sndinfo structure defined in Section 5.3.4 to this call. The
The input parameters accepted by this call include snd_sid, input parameters accepted by this call include snd_sid, snd_flags,
snd_flags, snd_ppid, snd_context. The snd_flags is composed of a snd_ppid, snd_context. The snd_flags is composed of a bitwise OR of
bitwise OR of SCTP_UNORDERED, SCTP_EOF, and SCTP_SENDALL. The SCTP_UNORDERED, SCTP_EOF, and SCTP_SENDALL. The snd_assoc_id field
snd_assoc_id field specifies the association to apply the parameters specifies the association to apply the parameters to. For a one-to-
to. For a one-to-many style socket any of the predefined constants many style socket any of the predefined constants are also allowed in
are also allowed in this field. The field is ignored on the one-to- this field. The field is ignored on the one-to-one style.
one style.
7.2. Read-Only Options 8.2. Read-Only Options
The options defined in this subsection are read-only. Using this The options defined in this subsection are read-only. Using this
option in a setsockopt() call will result in an error indicating option in a setsockopt() call will result in an error indicating
EOPNOTSUPP. EOPNOTSUPP.
7.2.1. Association Status (SCTP_STATUS) 8.2.1. Association Status (SCTP_STATUS)
Applications can retrieve current status information about an Applications can retrieve current status information about an
association, including association state, peer receiver window size, association, including association state, peer receiver window size,
number of unacked data chunks, and number of data chunks pending number of unacked data chunks, and number of data chunks pending
receipt. This information is read-only. receipt. This information is read-only.
The following structure is used to access this information: The following structure is used to access this information:
struct sctp_status { struct sctp_status {
sctp_assoc_t sstat_assoc_id; sctp_assoc_t sstat_assoc_id;
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uint16_t sstat_outstrms; uint16_t sstat_outstrms;
uint32_t sstat_fragmentation_point; uint32_t sstat_fragmentation_point;
struct sctp_paddrinfo sstat_primary; struct sctp_paddrinfo sstat_primary;
}; };
sstat_assoc_id: This parameter is ignored for one-to-one style sstat_assoc_id: This parameter is ignored for one-to-one style
sockets. For one-to-many style sockets it holds the identifier sockets. For one-to-many style sockets it holds the identifier
for the association. All notifications for a given association for the association. All notifications for a given association
have the same association identifier. The special SCTP_{FUTURE| have the same association identifier. The special SCTP_{FUTURE|
CURRENT|ALL}_ASSOC cannot be used. CURRENT|ALL}_ASSOC cannot be used.
sstat_state: This contains the association's current state, i.e. one sstat_state: This contains the association's current state, i.e. one
of the following values: of the following values:
* SCTP_CLOSED * SCTP_CLOSED
* SCTP_BOUND * SCTP_BOUND
* SCTP_LISTEN * SCTP_LISTEN
* SCTP_COOKIE_WAIT * SCTP_COOKIE_WAIT
* SCTP_COOKIE_ECHOED * SCTP_COOKIE_ECHOED
* SCTP_ESTABLISHED * SCTP_ESTABLISHED
* SCTP_SHUTDOWN_PENDING * SCTP_SHUTDOWN_PENDING
* SCTP_SHUTDOWN_SENT * SCTP_SHUTDOWN_SENT
* SCTP_SHUTDOWN_RECEIVED * SCTP_SHUTDOWN_RECEIVED
* SCTP_SHUTDOWN_ACK_SENT * SCTP_SHUTDOWN_ACK_SENT
sstat_rwnd: This contains the association peer's current receiver sstat_rwnd: This contains the association peer's current receiver
window size. window size.
sstat_unackdata: This is the number of unacked data chunks. sstat_unackdata: This is the number of unacked data chunks.
sstat_penddata: This is the number of data chunks pending receipt. sstat_penddata: This is the number of data chunks pending receipt.
sstat_instrms: The number of streams that the peer will be using sstat_instrms: The number of streams that the peer will be using
outbound. outbound.
sstat_outstrms: The number of streams that the endpoint is allowed sstat_outstrms: The number of streams that the endpoint is allowed
to use outbound. to use outbound.
sstat_fragmentation_point: The size at which SCTP fragmentation will sstat_fragmentation_point: The size at which SCTP fragmentation will
occur. occur.
sstat_primary: This is information on the current primary peer sstat_primary: This is information on the current primary peer
address. address.
To access these status values, the application calls getsockopt() To access these status values, the application calls getsockopt()
with the option name SCTP_STATUS. with the option name SCTP_STATUS.
7.2.2. Peer Address Information (SCTP_GET_PEER_ADDR_INFO) 8.2.2. Peer Address Information (SCTP_GET_PEER_ADDR_INFO)
Applications can retrieve information about a specific peer address Applications can retrieve information about a specific peer address
of an association, including its reachability state, congestion of an association, including its reachability state, congestion
window, and retransmission timer values. This information is read- window, and retransmission timer values. This information is read-
only. only.
The following structure is used to access this information: The following structure is used to access this information:
struct sctp_paddrinfo { struct sctp_paddrinfo {
sctp_assoc_t spinfo_assoc_id; sctp_assoc_t spinfo_assoc_id;
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int32_t spinfo_state; int32_t spinfo_state;
uint32_t spinfo_cwnd; uint32_t spinfo_cwnd;
uint32_t spinfo_srtt; uint32_t spinfo_srtt;
uint32_t spinfo_rto; uint32_t spinfo_rto;
uint32_t spinfo_mtu; uint32_t spinfo_mtu;
}; };
spinfo_assoc_id: This parameter is ignored for one-to-one style spinfo_assoc_id: This parameter is ignored for one-to-one style
sockets. For one-to-many style sockets the following applies: sockets. For one-to-many style sockets the following applies:
This field may be filled by the application, if so, this field This field may be filled by the application, if so, this field
will have priority in looking up the association using the address will have priority in looking up the association instead of using
specified in spinfo_address. Note that if the address does not the address specified in spinfo_address. Note that if the address
belong to the association specified then this call will fail. If does not belong to the association specified then this call will
the application does not fill in the spinfo_assoc_id, then the fail. If the application does not fill in the spinfo_assoc_id,
address will be used to lookup the association and on return this then the address will be used to lookup the association and on
field will have the valid association id. In other words, this return this field will have the valid association id. In other
call can be used to translate an address into an association id. words, this call can be used to translate an address into an
Note that the predefined constants are not allowed on this option. association id. Note that the predefined constants are not
allowed on this option.
spinfo_address: This is filled by the application, and contains the spinfo_address: This is filled by the application, and contains the
peer address of interest. peer address of interest.
spinfo_state: This contains the peer address' state (either
SCTP_ACTIVE or SCTP_INACTIVE and possibly the modifier spinfo_state: This contains the peer address' state:
SCTP_UNCONFIRMED).
SCTP_UNCONFIRMED: The initial state of a peer address.
SCTP_ACTIVE: The state is entered the first time after path
verification. It can also be entered if the state is
SCTP_INACTIVE and the path supervision detects that the peer
address is reachable again.
SCTP_INACTIVE: This state is entered whenever a path failure is
detected.
spinfo_cwnd: This contains the peer address' current congestion spinfo_cwnd: This contains the peer address' current congestion
window. window.
spinfo_srtt: This contains the peer address' current smoothed round- spinfo_srtt: This contains the peer address' current smoothed round-
trip time calculation in milliseconds. trip time calculation in milliseconds.
spinfo_rto: This contains the peer address' current retransmission spinfo_rto: This contains the peer address' current retransmission
timeout value in milliseconds. timeout value in milliseconds.
spinfo_mtu: The current P-MTU of this address.
7.2.3. Get the List of Chunks the Peer Requires to be Authenticated spinfo_mtu: The current path MTU of the peer address. It is the
number of bytes available in an SCTP packet for chunks.
8.2.3. Get the List of Chunks the Peer Requires to be Authenticated
(SCTP_PEER_AUTH_CHUNKS) (SCTP_PEER_AUTH_CHUNKS)
This option gets a list of chunk types (see [RFC4960]) for a This option gets a list of chunk types (see [RFC4960]) for a
specified association that the peer requires to be received specified association that the peer requires to be received
authenticated only. authenticated only.
The following structure is used to access these parameters: The following structure is used to access these parameters:
struct sctp_authchunks { struct sctp_authchunks {
sctp_assoc_t gauth_assoc_id; sctp_assoc_t gauth_assoc_id;
skipping to change at page 72, line 37 skipping to change at page 82, line 27
struct sctp_authchunks { struct sctp_authchunks {
sctp_assoc_t gauth_assoc_id; sctp_assoc_t gauth_assoc_id;
uint32_t gauth_number_of_chunks uint32_t gauth_number_of_chunks
uint8_t gauth_chunks[]; uint8_t gauth_chunks[];
}; };
gauth_assoc_id: This parameter indicates for which association the gauth_assoc_id: This parameter indicates for which association the
user is requesting the list of peer authenticated chunks. For user is requesting the list of peer authenticated chunks. For
one-to-one sockets, this parameter is ignored. Note that the one-to-one sockets, this parameter is ignored. Note that the
predefined constants are not allowed with this option. predefined constants are not allowed with this option.
gauth_number_of_chunks: This parameter gives the number of elements gauth_number_of_chunks: This parameter gives the number of elements
in the array gauth_chunks. in the array gauth_chunks.
gauth_chunks: This parameter contains an array of chunk types that gauth_chunks: This parameter contains an array of chunk types that
the peer is requesting to be authenticated. the peer is requesting to be authenticated. If the passed in
buffer size is not large enough to hold the list of chunk types,
ENOBUFS is returned.
7.2.4. Get the List of Chunks the Local Endpoint Requires to be 8.2.4. Get the List of Chunks the Local Endpoint Requires to be
Authenticated (SCTP_LOCAL_AUTH_CHUNKS) Authenticated (SCTP_LOCAL_AUTH_CHUNKS)
This option gets a list of chunk types (see [RFC4960]) for a This option gets a list of chunk types (see [RFC4960]) for a
specified association that the local endpoint requires to be received specified association that the local endpoint requires to be received
authenticated only. authenticated only.
The following structure is used to access these parameters: The following structure is used to access these parameters:
struct sctp_authchunks { struct sctp_authchunks {
sctp_assoc_t gauth_assoc_id; sctp_assoc_t gauth_assoc_id;
skipping to change at page 73, line 10 skipping to change at page 83, line 4
specified association that the local endpoint requires to be received specified association that the local endpoint requires to be received
authenticated only. authenticated only.
The following structure is used to access these parameters: The following structure is used to access these parameters:
struct sctp_authchunks { struct sctp_authchunks {
sctp_assoc_t gauth_assoc_id; sctp_assoc_t gauth_assoc_id;
uint32_t gauth_number_of_chunks; uint32_t gauth_number_of_chunks;
uint8_t gauth_chunks[]; uint8_t gauth_chunks[];
}; };
gauth_assoc_id: This parameter indicates for which association the gauth_assoc_id: This parameter indicates for which association the
user is requesting the list of local authenticated chunks. For user is requesting the list of local authenticated chunks. For
one-to-one sockets, this parameter is ignored. one-to-one sockets, this parameter is ignored.
gauth_number_of_chunks: This parameter gives the number of elements gauth_number_of_chunks: This parameter gives the number of elements
in the array gauth_chunks. in the array gauth_chunks.
gauth_chunks: This parameter contains an array of chunk types that gauth_chunks: This parameter contains an array of chunk types that
the local endpoint is requesting to be authenticated. the local endpoint is requesting to be authenticated. If the
passed in buffer is not large enough to hold the list of chunk
types, ENOBUFS is returned.
7.2.5. Get the Current Number of Associations (SCTP_GET_ASSOC_NUMBER) 8.2.5. Get the Current Number of Associations (SCTP_GET_ASSOC_NUMBER)
This option gets the current number of associations that are attached This option gets the current number of associations that are attached
to a one-to-many style socket. The option value is an uint32_t. to a one-to-many style socket. The option value is an uint32_t.
Note that this number is only a snap shot. This means that the Note that this number is only a snap shot. This means that the
number of associations may have changed when the caller gets back the number of associations may have changed when the caller gets back the
option result. option result.
For a one-to-one style socket, this socket option results in an For a one-to-one style socket, this socket option results in an
error. error.
7.2.6. Get the Current Identifiers of Associations 8.2.6. Get the Current Identifiers of Associations
(SCTP_GET_ASSOC_ID_LIST) (SCTP_GET_ASSOC_ID_LIST)
This option gets the current list of SCTP association identifiers of This option gets the current list of SCTP association identifiers of
the SCTP associations handled by a one-to-many style socket. the SCTP associations handled by a one-to-many style socket.
The option value has the structure The option value has the structure
struct sctp_assoc_ids { struct sctp_assoc_ids {
uint32_t gaids_number_of_ids; uint32_t gaids_number_of_ids;
sctp_assoc_t gaids_assoc_id[]; sctp_assoc_t gaids_assoc_id[];
}; };
The caller must provide a large enough buffer to hold all association The caller must provide a large enough buffer to hold all association
identifiers. If the buffer is too small, an error must be returned. identifiers. If the buffer is too small, an error must be returned.
The user can use the SCTP_GET_ASSOC_NUMBER socket option to get an The user can use the SCTP_GET_ASSOC_NUMBER socket option to get an
idea how large the buffer has to be. gaids_number_of_ids gives the idea how large the buffer has to be. gaids_number_of_ids gives the
number of elements in the array gaids_assoc_id. Note also that the number of elements in the array gaids_assoc_id. Note also that some
some or all of sctp_assoc_t returned in the array may become invalid or all of sctp_assoc_t returned in the array may become invalid by
by the time the caller gets back the result. the time the caller gets back the result.
For a one-to-one style socket, this socket option results in an For a one-to-one style socket, this socket option results in an
error. error.
7.3. Write-Only Options 8.3. Write-Only Options
The options defined in this subsection are write-only. Using this The options defined in this subsection are write-only. Using this
option in a getsockopt() or sctp_opt_info() call will result in an option in a getsockopt() or sctp_opt_info() call will result in an
error indicating EOPNOTSUPP. error indicating EOPNOTSUPP.
7.3.1. Set Peer Primary Address (SCTP_SET_PEER_PRIMARY_ADDR) 8.3.1. Set Peer Primary Address (SCTP_SET_PEER_PRIMARY_ADDR)
Requests that the peer marks the enclosed address as the association Requests that the peer marks the enclosed address as the association
primary (see [RFC5061]). The enclosed address must be one of the primary (see [RFC5061]). The enclosed address must be one of the
association's locally bound addresses. association's locally bound addresses.
The following structure is used to make a set peer primary request: The following structure is used to make a set peer primary request:
struct sctp_setpeerprim { struct sctp_setpeerprim {
sctp_assoc_t sspp_assoc_id; sctp_assoc_t sspp_assoc_id;
struct sockaddr_storage sspp_addr; struct sockaddr_storage sspp_addr;
skipping to change at page 74, line 25 skipping to change at page 84, line 25
association's locally bound addresses. association's locally bound addresses.
The following structure is used to make a set peer primary request: The following structure is used to make a set peer primary request:
struct sctp_setpeerprim { struct sctp_setpeerprim {
sctp_assoc_t sspp_assoc_id; sctp_assoc_t sspp_assoc_id;
struct sockaddr_storage sspp_addr; struct sockaddr_storage sspp_addr;
}; };
sspp_addr: The address to set as primary. sspp_addr: The address to set as primary.
sspp_assoc_id: This parameter is ignored for one-to-one style sspp_assoc_id: This parameter is ignored for one-to-one style
sockets. For one-to-many style sockets it identifies the sockets. For one-to-many style sockets it identifies the
association for this request. Note that the predefined constants association for this request. Note that the predefined constants
are not allowed on this option. are not allowed on this option.
7.3.2. Add a Chunk That Must Be Authenticated (SCTP_AUTH_CHUNK) 8.3.2. Add a Chunk That Must Be Authenticated (SCTP_AUTH_CHUNK)
This set option adds a chunk type that the user is requesting to be This set option adds a chunk type that the user is requesting to be
received only in an authenticated way. Changes to the list of chunks received only in an authenticated way. Changes to the list of chunks
will only affect future associations on the socket. will only affect future associations on the socket.
The following structure is used to add a chunk: The following structure is used to add a chunk:
struct sctp_authchunk { struct sctp_authchunk {
uint8_t sauth_chunk; uint8_t sauth_chunk;
}; };
sauth_chunk: This parameter contains a chunk type that the user is sauth_chunk: This parameter contains a chunk type that the user is
requesting to be authenticated. requesting to be authenticated.
The chunk types for INIT, INIT-ACK, SHUTDOWN-COMPLETE, and AUTH The chunk types for INIT, INIT-ACK, SHUTDOWN-COMPLETE, and AUTH
chunks must not be used. If they are used, an error must be chunks must not be used. If they are used, an error must be
returned. The usage of this option enables SCTP AUTH in cases where returned. The usage of this option enables SCTP AUTH in cases where
it is not required by other means (for example the use of dynamic it is not required by other means (for example the use of dynamic
address reconfiguration). address reconfiguration).
7.3.3. Set a Shared Key (SCTP_AUTH_KEY) 8.3.3. Set a Shared Key (SCTP_AUTH_KEY)
This option will set a shared secret key that is used to build an This option will set a shared secret key that is used to build an
association shared key. association shared key.
The following structure is used to access and modify these The following structure is used to access and modify these
parameters: parameters:
struct sctp_authkey { struct sctp_authkey {
sctp_assoc_t sca_assoc_id; sctp_assoc_t sca_assoc_id;
uint16_t sca_keynumber; uint16_t sca_keynumber;
uint16_t sca_keylength; uint16_t sca_keylength;
uint8_t sca_key[]; uint8_t sca_key[];
}; };
sca_assoc_id: This parameter indicates what association the shared sca_assoc_id: This parameter indicates what association the shared
key is being set upon. The special SCTP_{FUTURE|CURRENT| key is being set upon. The special SCTP_{FUTURE|CURRENT|
ALL}_ASSOC can be used. For one-to-one sockets, this parameter is ALL}_ASSOC can be used. For one-to-one sockets, this parameter is
ignored. Note, however, that this option will set a key on the ignored. Note, however on one to one sockets, that this option
association if the socket is connected, otherwise this will set a will set a key on the association if the socket is connected,
key on the endpoint. otherwise this will set a key on the endpoint.
sca_keynumber: This parameter is the shared key identifier by which sca_keynumber: This parameter is the shared key identifier by which
the application will refer to this shared key. If a key of the the application will refer to this shared key. If a key of the
specified index already exists, then this new key will replace the specified index already exists, then this new key will replace the
old existing key. Note that shared key identifier '0' defaults to old existing key. Note that shared key identifier '0' defaults to
a null key. a null key.
sca_keylength: This parameter is the length of the array sca_key. sca_keylength: This parameter is the length of the array sca_key.
sca_key: This parameter contains an array of bytes that is to be sca_key: This parameter contains an array of bytes that is to be
used by the endpoint (or association) as the shared secret key. used by the endpoint (or association) as the shared secret key.
Note, if the length of this field is zero, a null key is set. Note, if the length of this field is zero, a null key is set.
7.3.4. Deactivate a Shared Key (SCTP_AUTH_DEACTIVATE_KEY) 8.3.4. Deactivate a Shared Key (SCTP_AUTH_DEACTIVATE_KEY)
This set option indicates that the application will not send user This set option indicates that the application will no longer send
messages anymore using the indicated key identifier. user messages using the indicated key identifier.
struct sctp_authkeyid { struct sctp_authkeyid {
sctp_assoc_t scact_assoc_id; sctp_assoc_t scact_assoc_id;
uint16_t scact_keynumber; uint16_t scact_keynumber;
}; };
scact_assoc_id: This parameter indicates which association the scact_assoc_id: This parameter indicates which association the
shared key identifier is being deleted from. The special shared key identifier is being deleted from. The special
SCTP_{FUTURE|CURRENT|ALL}_ASSOC can be used. For one-to-one SCTP_{FUTURE|CURRENT|ALL}_ASSOC can be used. For one-to-one
sockets, this parameter is ignored. Note, however, that this sockets, this parameter is ignored. Note, however, that this
option will deactivate the key from the association if the socket option will deactivate the key from the association if the socket
is connected, otherwise this will deactivate the key from the is connected, otherwise this will deactivate the key from the
endpoint. endpoint.
scact_keynumber: This parameter is the shared key identifier which scact_keynumber: This parameter is the shared key identifier which
the application is requesting to be deactivated. The key the application is requesting to be deactivated. The key
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endpoint. endpoint.
scact_keynumber: This parameter is the shared key identifier which scact_keynumber: This parameter is the shared key identifier which
the application is requesting to be deactivated. The key the application is requesting to be deactivated. The key
identifier must correspond to an existing shared key. Note if identifier must correspond to an existing shared key. Note if
this parameter is zero, use of the null key identifier '0' is this parameter is zero, use of the null key identifier '0' is
deactivated on the endpoint and/or association. deactivated on the endpoint and/or association.
The currently active key cannot be deactivated. The currently active key cannot be deactivated.
7.3.5. Delete a Shared Key (SCTP_AUTH_DELETE_KEY) 8.3.5. Delete a Shared Key (SCTP_AUTH_DELETE_KEY)
This set option will delete a shared secret key which has been This set option will delete a shared secret key which has been
deactivated of an SCTP association. deactivated of an SCTP association.
struct sctp_authkeyid { struct sctp_authkeyid {
sctp_assoc_t scact_assoc_id; sctp_assoc_t scact_assoc_id;
uint16_t scact_keynumber; uint16_t scact_keynumber;
}; };
scact_assoc_id: This parameter indicates which association the scact_assoc_id: This parameter indicates which association the
skipping to change at page 76, line 29 skipping to change at page 86, line 36
sctp_assoc_t scact_assoc_id; sctp_assoc_t scact_assoc_id;
uint16_t scact_keynumber; uint16_t scact_keynumber;
}; };
scact_assoc_id: This parameter indicates which association the scact_assoc_id: This parameter indicates which association the
shared key identifier is being deleted from. The special shared key identifier is being deleted from. The special
SCTP_{FUTURE|CURRENT|ALL}_ASSOC can be used. For one-to-one SCTP_{FUTURE|CURRENT|ALL}_ASSOC can be used. For one-to-one
sockets, this parameter is ignored. Note, however, that this sockets, this parameter is ignored. Note, however, that this
option will delete the key from the association if the socket is option will delete the key from the association if the socket is
connected, otherwise this will delete the key from the endpoint. connected, otherwise this will delete the key from the endpoint.
scact_keynumber: This parameter is the shared key identifier which scact_keynumber: This parameter is the shared key identifier which
the application is requesting to be deleted. The key identifier the application is requesting to be deleted. The key identifier
must correspond to an existing shared key and must not be in use must correspond to an existing shared key and must not be in use
for any packet being sent by the SCTP implementation. This means for any packet being sent by the SCTP implementation. This means
in particular, that it must be deactivated first. Note if this in particular, that it must be deactivated first. Note if this
parameter is zero, use of the null key identifier '0' is deleted parameter is zero, use of the null key identifier '0' is deleted
from the endpoint and/or association. from the endpoint and/or association.
Only deactivated keys that are no longer used by the association can Only deactivated keys that are no longer used by an association can
be deleted. be deleted.
7.4. Ancillary Data and Notification Interest Options 9. New Functions
Applications can receive per-message ancillary information and
notifications of certain SCTP events with recvmsg().
The following optional information is available to the application:
SCTP_SNDRCV (sctp_data_io_event): Per-message information (i.e.
stream number, TSN, SSN, etc. described in Section 5.2.2)
SCTP_ASSOC_CHANGE (sctp_association_event): described in
Section 5.3.2
SCTP_PEER_ADDR_CHANGE (sctp_address_event): described in
Section 5.3.3
SCTP_SEND_FAILED (sctp_send_failure_event): described in
Section 5.3.5
SCTP_REMOTE_ERROR (sctp_peer_error_event): described in
Section 5.3.4
SCTP_SHUTDOWN_EVENT (sctp_shutdown_event): described in
Section 5.3.6
SCTP_PARTIAL_DELIVERY_EVENT (sctp_partial_delivery_event): described
in Section 5.3.8
SCTP_ADAPTATION_INDICATION (sctp_adaptation_layer_event): described
in Section 5.3.7
SCTP_AUTHENTICATION_EVENT (sctp_authentication_event): described in
Section 5.3.9)
SCTP_SENDER_DRY_EVENT (sctp_sender_dry_event): described in
Section 5.3.10
SCTP_NOTIFICATIONS_STOPPED_EVENT (): described in Section 5.3.11
To receive any ancillary data or notifications, first the application
registers its interest by calling the SCTP_EVENTS (deprecated, see
below) setsockopt() with the following structure:
struct sctp_event_subscribe{
uint8_t sctp_data_io_event;
uint8_t sctp_association_event;
uint8_t sctp_address_event;
uint8_t sctp_send_failure_event;
uint8_t sctp_peer_error_event;
uint8_t sctp_shutdown_event;
uint8_t sctp_partial_delivery_event;
uint8_t sctp_adaptation_layer_event;
uint8_t sctp_authentication_event;
uint8_t sctp_sender_dry_event;
};
sctp_data_io_event: Setting this flag to 1 will cause the reception
of SCTP_SNDRCV information on a per message basis. The
application will need to use the recvmsg() interface so that it
can receive the event information contained in the msg_control
field. Setting the flag to 0 will disable the reception of the
message control information.
sctp_association_event: Setting this flag to 1 will enable the
reception of association event notifications. Setting the flag to
0 will disable association event notifications.
sctp_address_event: Setting this flag to 1 will enable the reception
of address event notifications. Setting the flag to 0 will
disable address event notifications.
sctp_send_failure_event: Setting this flag to 1 will enable the
reception of send failure event notifications. Setting the flag
to 0 will disable send failure event notifications.
sctp_peer_error_event: Setting this flag to 1 will enable the
reception of peer error event notifications. Setting the flag to
0 will disable peer error event notifications.
sctp_shutdown_event: Setting this flag to 1 will enable the
reception of shutdown event notifications. Setting the flag to 0
will disable shutdown event notifications.
sctp_partial_delivery_event: Setting this flag to 1 will enable the
reception of partial delivery notifications. Setting the flag to
0 will disable partial delivery event notifications.
sctp_adaptation_layer_event: Setting this flag to 1 will enable the
reception of adaptation layer notifications. Setting the flag to
0 will disable adaptation layer event notifications.
sctp_authentication_event: Setting this flag to 1 will enable the
reception of authentication layer notifications. Setting the flag
to 0 will disable authentication layer event notifications.
sctp_sender_dry_event: Setting this flag to 1 will enable the
reception of sender dry notifications. Setting the flag to 0 will
disable sender dry event notifications.
An example where an application would like to receive data io events
and association events but no others would be as follows:
{
struct sctp_event_subscribe events;
memset(&events,0,sizeof(events));
events.sctp_data_io_event = 1;
events.sctp_association_event = 1;
setsockopt(fd, IPPROTO_SCTP, SCTP_EVENTS, &events, sizeof(events));
}
Note that for one-to-many style SCTP sockets, the caller of recvmsg()
receives ancillary data and notifications for all associations bound
to the file descriptor. For one-to-one style SCTP sockets, the
caller receives ancillary data and notifications only for the single
association bound to the file descriptor.
The SCTP_EVENTS socket option has one issue for future compatibility.
As new features are added the structure (sctp_event_subscribe) must
be expanded. This can cause an application binary interface (ABI)
issue unless an implementation has added padding at the end of the
structure. To avoid this problem, SCTP_EVENTS has been deprecated
and a new option SCTP_EVENT socket option has taken its place. The
option is used with the following structure:
struct sctp_event {
sctp_assoc_t se_assoc_id;
uint16_t se_type;
uint8_t se_on;
};
se_assoc_id: The se_assoc_id field is ignored for one-to-one style
sockets. For one-to-many style sockets any this field can be a
particular association id or SCTP_{FUTURE|CURRENT|ALL}_ASSOC.
se_type: The se_type field can be filled with any value that would
show up in the respective sn_type field (in the sctp_tlv structure
of the notification).
se_on: The se_on field is set to 1 to turn on an event and set to 0
to turn off an event.
To use this option the user fills in this structure and then calls
the setsockopt to turn on or off an individual event. The following
is an example use of this option:
{
struct sctp_event event;
memset(&event, 0, sizeof(event));
event.se_assoc_id = SCTP_FUTURE_ASSOC;
event.se_type = SCTP_SENDER_DRY_EVENT;
event.se_on = 1;
setsockopt(fd, IPPROTO_SCTP, SCTP_EVENT, &event, sizeof(event));
}
By default both the one-to-one style and the one-to-many style socket
has all options off.
8. New Functions
Depending on the system, the following interface can be implemented Depending on the system, the following interface can be implemented
as a system call or library function. as a system call or library function.
8.1. sctp_bindx() 9.1. sctp_bindx()
This function allows the user to bind a specific subset of addresses This function allows the user to bind a specific subset of addresses
or, if the SCTP extension described in [RFC5061] is supported, add or or, if the SCTP extension described in [RFC5061] is supported, add or
delete specific addresses. delete specific addresses.
The function prototype is The function prototype is
int sctp_bindx(int sd, int sctp_bindx(int sd,
struct sockaddr *addrs, struct sockaddr *addrs,
int addrcnt, int addrcnt,
skipping to change at page 80, line 36 skipping to change at page 87, line 42
on a socket with this function, doing so will result in an error. on a socket with this function, doing so will result in an error.
On success, sctp_bindx() returns 0. On failure, sctp_bindx() returns On success, sctp_bindx() returns 0. On failure, sctp_bindx() returns
-1 and sets errno to the appropriate error code. -1 and sets errno to the appropriate error code.
For SCTP, the port given in each socket address must be the same, or For SCTP, the port given in each socket address must be the same, or
sctp_bindx() will fail, setting errno to EINVAL. sctp_bindx() will fail, setting errno to EINVAL.
The flags parameter is formed from the bitwise OR of zero or more of The flags parameter is formed from the bitwise OR of zero or more of
the following currently defined flags: the following currently defined flags:
o SCTP_BINDX_ADD_ADDR o SCTP_BINDX_ADD_ADDR
o SCTP_BINDX_REM_ADDR o SCTP_BINDX_REM_ADDR
SCTP_BINDX_ADD_ADDR directs SCTP to add the given addresses to the SCTP_BINDX_ADD_ADDR directs SCTP to add the given addresses to the
association, and SCTP_BINDX_REM_ADDR directs SCTP to remove the given socket (i.e. endpoint), and SCTP_BINDX_REM_ADDR directs SCTP to
addresses from the association. The two flags are mutually remove the given addresses from the socket. The two flags are
exclusive; if both are given, sctp_bindx() will fail with EINVAL. A mutually exclusive; if both are given, sctp_bindx() will fail with
caller may not remove all addresses from an association; sctp_bindx() EINVAL. A caller may not remove all addresses from a socket;
will reject such an attempt with EINVAL. sctp_bindx() will reject such an attempt with EINVAL.
An application can use sctp_bindx(SCTP_BINDX_ADD_ADDR) to associate An application can use sctp_bindx(SCTP_BINDX_ADD_ADDR) to associate
additional addresses with an endpoint after calling bind(). Or use additional addresses with an endpoint after calling bind(). Or use
sctp_bindx(SCTP_BINDX_REM_ADDR) to remove some addresses a listening sctp_bindx(SCTP_BINDX_REM_ADDR) to remove some addresses a listening
socket is associated with, so that no new association accepted will socket is associated with, so that no new association accepted will
be associated with these addresses. If the endpoint supports dynamic be associated with these addresses. If the endpoint supports dynamic
address reconfiguration an SCTP_BINDX_REM_ADDR or SCTP_BINDX_ADD_ADDR address reconfiguration, an SCTP_BINDX_REM_ADDR or
may cause an endpoint to send the appropriate message to the peer to SCTP_BINDX_ADD_ADDR may cause an endpoint to send the appropriate
change the peer's address lists. message to its peers to change the peers' address lists.
Adding and removing addresses from a connected association is an Adding and removing addresses from established associations is an
optional functionality. Implementations that do not support this optional functionality. Implementations that do not support this
functionality should return -1 and set errno to EOPNOTSUPP. functionality should return -1 and set errno to EOPNOTSUPP.
sctp_bindx() can be called on an already bound socket or on an sctp_bindx() can be called on an already bound socket or on an
unbound socket. If the socket is unbound and the first port number unbound socket. If the socket is unbound and the first port number
in the addrs is zero, the kernel will choose a port number. All port in the addrs is zero, the kernel will choose a port number. All port
numbers after the first one being 0 must also be zero. If the first numbers after the first one being 0 must also be zero. If the first
port number is not zero, the following port numbers must be zero or port number is not zero, the following port numbers must be zero or
have the same value as the first one. For an already bound socket, have the same value as the first one. For an already bound socket,
all port numbers provided must be the bound one or 0. all port numbers provided must be the bound one or 0.
sctp_bindx() is an atomic operation. Therefore, the binding will be sctp_bindx() is an atomic operation. Therefore, the binding will be
either successful on all addresses or fail on all addresses. If either successful on all addresses or fail on all addresses. If
multiple addresses are provided and the sctp_bindx() call fails there multiple addresses are provided and the sctp_bindx() call fails there
is no indication which address is responsible for the failure. The is no indication which address is responsible for the failure. The
only way to get a specific error indication is to call sctp_bindx() only way to identify the specific error indication is to call
with only one address sequentially. sctp_bindx() sequentially with only one address per call.
8.2. sctp_peeloff() 9.2. sctp_peeloff()
After an association is established on a one-to-many style socket, After an association is established on a one-to-many style socket,
the application may wish to branch off the association into a the application may wish to branch off the association into a
separate socket/file descriptor. separate socket/file descriptor.
This is particularly desirable when, for instance, the application This is particularly desirable when, for instance, the application
wishes to have a number of sporadic message senders/receivers remain wishes to have a number of sporadic message senders/receivers remain
under the original one-to-many style socket, but branch off these under the original one-to-many style socket, but branch off these
associations carrying high volume data traffic into their own associations carrying high volume data traffic into their own
separate socket descriptors. separate socket descriptors.
skipping to change at page 82, line 4 skipping to change at page 89, line 11
changed from the traditional one-to-one style accept() call). Note changed from the traditional one-to-one style accept() call). Note
that the new socket is a one-to-one style socket. Thus it will be that the new socket is a one-to-one style socket. Thus it will be
confined to operations allowed for a one-to-one style socket. confined to operations allowed for a one-to-one style socket.
The function prototype is The function prototype is
int sctp_peeloff(int sd, int sctp_peeloff(int sd,
sctp_assoc_t assoc_id); sctp_assoc_t assoc_id);
and the arguments are and the arguments are
sd: The original one-to-many style socket descriptor returned from sd: The original one-to-many style socket descriptor returned from
the socket() system call (see Section 3.1.1). the socket() system call (see Section 3.1.1).
assoc_id: the specified identifier of the association that is to be assoc_id: the specified identifier of the association that is to be
branched off to a separate file descriptor (Note, in a traditional branched off to a separate file descriptor (Note, in a traditional
one-to-one style accept() call, this would be an out parameter, one-to-one style accept() call, this would be an out parameter,
but for the one-to-many style call, this is an in parameter). but for the one-to-many style call, this is an in parameter).
The function returns a non-negative file descriptor representing the The function returns a non-negative file descriptor representing the
branched-off association, or -1 if an error occurred. The variable branched-off association, or -1 if an error occurred. The variable
errno is then set appropriately. errno is then set appropriately.
8.3. sctp_getpaddrs() 9.3. sctp_getpaddrs()
sctp_getpaddrs() returns all peer addresses in an association. sctp_getpaddrs() returns all peer addresses in an association.
The function protoype is: The function prototype is:
int sctp_getpaddrs(int sd, int sctp_getpaddrs(int sd,
sctp_assoc_t id, sctp_assoc_t id,
struct sockaddr **addrs); struct sockaddr **addrs);
On return, addrs will point to an array dynamically allocated On return, addrs will point to a dynamically allocated array of
sockaddr structures of the appropriate type for the socket type. The sockaddr structures of the appropriate type for the socket type. The
caller should use sctp_freepaddrs() to free the memory. Note that caller should use sctp_freepaddrs() to free the memory. Note that
the in/out parameter addrs must not be NULL. the in/out parameter addrs must not be NULL.
If sd is an IPv4 socket, the addresses returned will be all IPv4 If sd is an IPv4 socket, the addresses returned will be all IPv4
addresses. If sd is an IPv6 socket, the addresses returned can be a addresses. If sd is an IPv6 socket, the addresses returned can be a
mix of IPv4 or IPv6 addresses. mix of IPv4 or IPv6 addresses, with IPv4 addresses returned according
to the SCTP_I_WANT_MAPPED_V4_ADDR option setting.
For one-to-many style sockets, id specifies the association to query. For one-to-many style sockets, id specifies the association to query.
For one-to-one style sockets, id is ignored. For one-to-one style sockets, id is ignored.
On success, sctp_getpaddrs() returns the number of peer addresses in On success, sctp_getpaddrs() returns the number of peer addresses in
the association. If there is no association on this socket, the association. If there is no association on this socket,
sctp_getpaddrs() returns 0, and the value of *addrs is undefined. If sctp_getpaddrs() returns 0, and the value of *addrs is undefined. If
an error occurs, sctp_getpaddrs() returns -1, and the value of *addrs an error occurs, sctp_getpaddrs() returns -1, and the value of *addrs
is undefined. is undefined.
8.4. sctp_freepaddrs() 9.4. sctp_freepaddrs()
sctp_freepaddrs() frees all resources allocated by sctp_getpaddrs(). sctp_freepaddrs() frees all resources allocated by sctp_getpaddrs().
The function prototype is The function prototype is
void sctp_freepaddrs(struct sockaddr *addrs); void sctp_freepaddrs(struct sockaddr *addrs);
and addrs is the array of peer addresses returned by and addrs is the array of peer addresses returned by
sctp_getpaddrs(). sctp_getpaddrs().
8.5. sctp_getladdrs() 9.5. sctp_getladdrs()
sctp_getladdrs() returns all locally bound address(es) on a socket. sctp_getladdrs() returns all locally bound address(es) on a socket.
The function prototype is The function prototype is
int sctp_getladdrs(int sd, int sctp_getladdrs(int sd,
sctp_assoc_t id, sctp_assoc_t id,
struct sockaddr **addrs); struct sockaddr **addrs);
On return, addrs will point to a dynamically allocated array of On return, addrs will point to a dynamically allocated array of
sockaddr structures of the appropriate type for the socket type. The sockaddr structures of the appropriate type for the socket type. The
caller should use sctp_freeladdrs() to free the memory. Note that caller should use sctp_freeladdrs() to free the memory. Note that
the in/out parameter addrs must not be NULL. the in/out parameter addrs must not be NULL.
If sd is an IPv4 socket, the addresses returned will be all IPv4 If sd is an IPv4 socket, the addresses returned will be all IPv4
addresses. If sd is an IPv6 socket, the addresses returned can be a addresses. If sd is an IPv6 socket, the addresses returned can be a
mix of IPv4 or IPv6 addresses. mix of IPv4 or IPv6 addresses, with IPv4 addresses returned according
to the SCTP_I_WANT_MAPPED_V4_ADDR option setting.
For one-to-many style sockets, id specifies the association to query. For one-to-many style sockets, id specifies the association to query.
For one-to-one style sockets, id is ignored. For one-to-one style sockets, id is ignored.
If the id field is set to the value '0' then the locally bound If the id field is set to the value '0' then the locally bound
addresses are returned without regard to any particular association. addresses are returned without regard to any particular association.
On success, sctp_getladdrs() returns the number of local addresses On success, sctp_getladdrs() returns the number of local addresses
bound to the socket. If the socket is unbound, sctp_getladdrs() bound to the socket. If the socket is unbound, sctp_getladdrs()
returns 0, and the value of *addrs is undefined. If an error occurs, returns 0, and the value of *addrs is undefined. If an error occurs,
sctp_getladdrs() returns -1, and the value of *addrs is undefined. sctp_getladdrs() returns -1, and the value of *addrs is undefined.
8.6. sctp_freeladdrs() 9.6. sctp_freeladdrs()
sctp_freeladdrs() frees all resources allocated by sctp_getladdrs(). sctp_freeladdrs() frees all resources allocated by sctp_getladdrs().
The function prototype is The function prototype is
void sctp_freeladdrs(struct sockaddr *addrs); void sctp_freeladdrs(struct sockaddr *addrs);
and addrs is the array of local addresses returned by and addrs is the array of local addresses returned by
sctp_getladdrs(). sctp_getladdrs().
8.7. sctp_sendmsg() 9.7. sctp_sendmsg() - DEPRECATED
This function is deprecated, sctp_sendv() should be used instead. This function is deprecated, sctp_sendv() (see Section 9.13) should
be used instead.
An implementation may provide a library function (or possibly system An implementation may provide a library function (or possibly system
call) to assist the user with the advanced features of SCTP. call) to assist the user with the advanced features of SCTP.
The function prototype is The function prototype is
ssize_t sctp_sendmsg(int sd, ssize_t sctp_sendmsg(int sd,
const void *msg, const void *msg,
size_t len, size_t len,
const struct sockaddr *to, const struct sockaddr *to,
socklen_t tolen, socklen_t tolen,
uint32_t ppid, uint32_t ppid,
uint32_t flags, uint32_t flags,
uint16_t stream_no, uint16_t stream_no,
uint32_t pr_value, uint32_t timetolive,
uint32_t context); uint32_t context);
and the arguments are: and the arguments are:
sd: The socket descriptor. sd: The socket descriptor.
msg: The message to be sent. msg: The message to be sent.
len: The length of the message. len: The length of the message.
to: The destination address of the message. to: The destination address of the message.
tolen: The length of the destination address. tolen: The length of the destination address.
ppid: The same as sinfo_ppid (see Section 5.2.2).
flags: The same as sinfo_flags (see Section 5.2.2). ppid: The same as sinfo_ppid (see Section 5.3.2).
stream_no: The same as sinfo_stream (see Section 5.2.2).
pr_value: The same as sinfo_pr_value (see Section 5.2.2). flags: The same as sinfo_flags (see Section 5.3.2).
context: The same as sinfo_context (see Section 5.2.2).
stream_no: The same as sinfo_stream (see Section 5.3.2).
timetolive: The same as sinfo_timetolive (see Section 5.3.2).
context: The same as sinfo_context (see Section 5.3.2).
The call returns the number of characters sent, or -1 if an error The call returns the number of characters sent, or -1 if an error
occurred. The variable errno is then set appropriately. occurred. The variable errno is then set appropriately.
Sending a message using sctp_sendmsg() is atomic (unless explicit EOR Sending a message using sctp_sendmsg() is atomic (unless explicit EOR
marking is enabled on the socket specified by sd). marking is enabled on the socket specified by sd).
Using sctp_sendmsg() on a non-connected one-to-one style socket for Using sctp_sendmsg() on a non-connected one-to-one style socket for
implicit connection setup may or may not work depending on the SCTP implicit connection setup may or may not work depending on the SCTP
implementation. implementation.
8.8. sctp_recvmsg() 9.8. sctp_recvmsg() - DEPRECATED
This function is deprecated, sctp_recvv() should be used instead. This function is deprecated, sctp_recvv() (see Section 9.12) should
be used instead.
An implementation may provide a library function (or possibly system An implementation may provide a library function (or possibly system
call) to assist the user with the advanced features of SCTP. Note call) to assist the user with the advanced features of SCTP. Note
that in order for the sctp_sndrcvinfo structure to be filled in by that in order for the sctp_sndrcvinfo structure to be filled in by
sctp_recvmsg() the caller must enable the sctp_data_io_events with sctp_recvmsg() the caller must enable the sctp_data_io_events with
the SCTP_EVENTS option. Note that the setting of the the SCTP_EVENTS option. Note that the setting of the
SCTP_USE_EXT_RCVINFO will affect this function as well, causing the SCTP_USE_EXT_RCVINFO will affect this function as well, causing the
sctp_sndrcvinfo information to be extended. sctp_sndrcvinfo information to be extended.
The function prototype is The function prototype is
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An implementation may provide a library function (or possibly system An implementation may provide a library function (or possibly system
call) to assist the user with the advanced features of SCTP. Note call) to assist the user with the advanced features of SCTP. Note
that in order for the sctp_sndrcvinfo structure to be filled in by that in order for the sctp_sndrcvinfo structure to be filled in by
sctp_recvmsg() the caller must enable the sctp_data_io_events with sctp_recvmsg() the caller must enable the sctp_data_io_events with
the SCTP_EVENTS option. Note that the setting of the the SCTP_EVENTS option. Note that the setting of the
SCTP_USE_EXT_RCVINFO will affect this function as well, causing the SCTP_USE_EXT_RCVINFO will affect this function as well, causing the
sctp_sndrcvinfo information to be extended. sctp_sndrcvinfo information to be extended.
The function prototype is The function prototype is
ssize_t sctp_recvmsg(int sd, ssize_t sctp_recvmsg(int sd,
void *msg, void *msg,
size_t len, size_t len,
struct sockaddr *from, struct sockaddr *from,
socklen_t *fromlen socklen_t *fromlen
struct sctp_sndrcvinfo *sinfo struct sctp_sndrcvinfo *sinfo
int *msg_flags); int *msg_flags);
and the arguments are and the arguments are
sd: The socket descriptor. sd: The socket descriptor.
msg: The message buffer to be filled. msg: The message buffer to be filled.
len: The length of the message buffer. len: The length of the message buffer.
from: A pointer to an address to be filled with the sender of this from: A pointer to an address to be filled with the sender of this
messages address. messages address.
fromlen: An in/out parameter describing the from length. fromlen: An in/out parameter describing the from length.
sinfo: A pointer to an sctp_sndrcvinfo structure to be filled upon sinfo: A pointer to an sctp_sndrcvinfo structure to be filled upon
receipt of the message. receipt of the message.
msg_flags: A pointer to an integer to be filled with any message msg_flags: A pointer to an integer to be filled with any message
flags (e.g. MSG_NOTIFICATION). Note that this field is an in-out flags (e.g. MSG_NOTIFICATION). Note that this field is an in-out
field. Options for the receive may also be passed into the value field. Options for the receive may also be passed into the value
(e.g. MSG_PEEK). On return from the call, the msg_flags value (e.g. MSG_PEEK). On return from the call, the msg_flags value
will be different than what was sent in to the call. If will be different than what was sent in to the call. If
implemented via a recvmsg() call, the msg_flags should only implemented via a recvmsg() call, the msg_flags should only
contain the value of the flags from the recvmsg() call. contain the value of the flags from the recvmsg() call.
The call returns the number of bytes received, or -1 if an error The call returns the number of bytes received, or -1 if an error
occurred. The variable errno is then set appropriately. occurred. The variable errno is then set appropriately.
8.9. sctp_connectx() 9.9. sctp_connectx()
An implementation may provide a library function (or possibly system An implementation may provide a library function (or possibly system
call) to assist the user with associating to an endpoint that is call) to assist the user with associating to an endpoint that is
multi-homed. Much like sctp_bindx() this call allows a caller to multi-homed. Much like sctp_bindx() this call allows a caller to
specify multiple addresses at which a peer can be reached. The way specify multiple addresses at which a peer can be reached. The way
the SCTP stack uses the list of addresses to set up the association the SCTP stack uses the list of addresses to set up the association
is implementation dependent. This function only specifies that the is implementation dependent. This function only specifies that the
stack will try to make use of all the addresses in the list when stack will try to make use of all the addresses in the list when
needed. needed.
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stack will try to make use of all the addresses in the list when stack will try to make use of all the addresses in the list when
needed. needed.
Note that the list of addresses passed in is only used for setting up Note that the list of addresses passed in is only used for setting up
the association. It does not necessarily equal the set of addresses the association. It does not necessarily equal the set of addresses
the peer uses for the resulting association. If the caller wants to the peer uses for the resulting association. If the caller wants to
find out the set of peer addresses, it must use sctp_getpaddrs() to find out the set of peer addresses, it must use sctp_getpaddrs() to
retrieve them after the association has been set up. retrieve them after the association has been set up.
The function prototype is The function prototype is
int sctp_connectx(int sd, int sctp_connectx(int sd,
struct sockaddr *addrs, struct sockaddr *addrs,
int addrcnt, int addrcnt,
sctp_assoc_t *id); sctp_assoc_t *id);
and the arguments are: and the arguments are:
sd: The socket descriptor. sd: The socket descriptor.
addrs: An (packed) array of addresses.
addrs: An array of addresses.
addrcnt: The number of addresses in the array. addrcnt: The number of addresses in the array.
id: An output parameter that if passed in as a non-NULL will return id: An output parameter that if passed in as a non-NULL will return
the association identification for the newly created association the association identification for the newly created association
(if successful). (if successful).
The call returns 0 on success or -1 if an error occurred. The The call returns 0 on success or -1 if an error occurred. The
variable errno is then set appropriately. variable errno is then set appropriately.
8.10. sctp_send() 9.10. sctp_send() - DEPRECATED
This function is deprecated, sctp_sendv() should be used instead. This function is deprecated, sctp_sendv() should be used instead.
An implementation may provide another alternative function or system An implementation may provide another alternative function or system
call to assist an application with the sending of data without the call to assist an application with the sending of data without the
use of the CMSG header structures. use of the CMSG header structures.
The function prototype is The function prototype is
ssize_t sctp_send(int sd, ssize_t sctp_send(int sd,
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The function prototype is The function prototype is
ssize_t sctp_send(int sd, ssize_t sctp_send(int sd,
const void *msg, const void *msg,
size_t len, size_t len,
const struct sctp_sndrcvinfo *sinfo, const struct sctp_sndrcvinfo *sinfo,
int flags); int flags);
and the arguments are and the arguments are
sd: The socket descriptor. sd: The socket descriptor.
msg: The message to be sent. msg: The message to be sent.
len: The length of the message. len: The length of the message.
sinfo: A pointer to an sctp_sndrcvinfo structure used as described sinfo: A pointer to an sctp_sndrcvinfo structure used as described
in Section 5.2.2 for a sendmsg() call. in Section 5.3.2 for a sendmsg() call.
flags: The same flags as used by the sendmsg() call flags (e.g. flags: The same flags as used by the sendmsg() call flags (e.g.
MSG_DONTROUTE). MSG_DONTROUTE).
The call returns the number of bytes sent, or -1 if an error The call returns the number of bytes sent, or -1 if an error
occurred. The variable errno is then set appropriately. occurred. The variable errno is then set appropriately.
This function call may also be used to terminate an association using This function call may also be used to terminate an association using
an association identification by setting the sinfo.sinfo_flags to an association identification by setting the sinfo.sinfo_flags to
SCTP_EOF and the sinfo.sinfo_assoc_id to the association that needs SCTP_EOF and the sinfo.sinfo_assoc_id to the association that needs
to be terminated. In such a case the len of the message can be zero. to be terminated. In such a case the len of the message can be zero.
Using sctp_send() on a non-connected one-to-one style socket for Using sctp_send() on a non-connected one-to-one style socket for
implicit connection setup may or may not work depending on the SCTP implicit connection setup may or may not work depending on the SCTP
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SCTP_EOF and the sinfo.sinfo_assoc_id to the association that needs SCTP_EOF and the sinfo.sinfo_assoc_id to the association that needs
to be terminated. In such a case the len of the message can be zero. to be terminated. In such a case the len of the message can be zero.
Using sctp_send() on a non-connected one-to-one style socket for Using sctp_send() on a non-connected one-to-one style socket for
implicit connection setup may or may not work depending on the SCTP implicit connection setup may or may not work depending on the SCTP
implementation. implementation.