--- 1/draft-ietf-dnssd-push-12.txt 2017-10-30 07:14:54.613563413 -0700 +++ 2/draft-ietf-dnssd-push-13.txt 2017-10-30 07:14:54.689565212 -0700 @@ -1,19 +1,19 @@ Internet Engineering Task Force T. Pusateri -Internet-Draft Seeking affiliation +Internet-Draft Unaffiliated Intended status: Standards Track S. Cheshire -Expires: January 3, 2018 Apple Inc. - July 2, 2017 +Expires: May 2, 2018 Apple Inc. + October 29, 2017 DNS Push Notifications - draft-ietf-dnssd-push-12 + draft-ietf-dnssd-push-13 Abstract The Domain Name System (DNS) was designed to return matching records efficiently for queries for data that is relatively static. When those records change frequently, DNS is still efficient at returning the updated results when polled, as long as the polling rate is not too high. But there exists no mechanism for a client to be asynchronously notified when these changes occur. This document defines a mechanism for a client to be notified of such changes to @@ -27,21 +27,21 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on January 3, 2018. + This Internet-Draft will expire on May 2, 2018. Copyright Notice Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents @@ -229,22 +229,22 @@ "Print" button again when they wake their phone up. A DNS Push Notification client must not routinely keep a DNS Push Notification subscription active 24 hours a day, 7 days a week, just to keep a list in memory up to date so that if the user does choose to bring up an on-screen display of that data, it can be displayed really fast. DNS Push Notifications are designed to be fast enough that there is no need to pre-load a "warm" list in memory just in case it might be needed later. - Generally, as described in the DNS Session Signaling specification - [SessSig], a client must not keep a connection to a server open + Generally, as described in the DNS Stateful Operations specification + [StatefulOp], a client must not keep a connection to a server open indefinitely if it has no subscriptions (or other operations) active on that connection. A client MAY close a connection as soon as it becomes idle, and then if needed in the future, open a new connection when required. Alternatively, a client MAY speculatively keep an idle connection open for some time, subject to the constraint that it MUST NOT keep a connection open that has been idle for more than the session's idle timeout (15 seconds by default). 4. Transport @@ -292,48 +292,48 @@ connections to alternate DNS servers that support DNS Push Notifications for the zone and distribute subscriptions at its discretion. In this way, both clients and servers can react to resource constraints. Token bucket rate limiting schemes are also effective in providing fairness by a server across numerous client requests. 6. Protocol Operation The DNS Push Notification protocol is a session-oriented protocol, - and makes use of DNS Session Signaling [SessSig]. + and makes use of DNS Stateful Operations [StatefulOp]. - For details of the DNS Session Signaling message format refer to the - DNS Session Signaling specification [SessSig]. Those details are not - repeated here. + For details of the DNS Stateful Operations message format refer to + the DNS Stateful Operations specification [StatefulOp]. Those + details are not repeated here. - DNS Push Notification clients and servers MUST support DNS Session - Signaling, but the server SHOULD NOT issue any DNS Session Signaling - operations until after the client has first initiated a DNS Session - Signaling operation of its own. A single server can support DNS - Queries, DNS Updates, and DNS Push Notifications (using DNS Session - Signaling) on the same TCP port, and until the client has sent at - least one DNS Session Signaling operation the server does not know + DNS Push Notification clients and servers MUST support DNS Stateful + Operations, but the server SHOULD NOT issue any DNS Stateful + Operations messages until after the client has first initiated a DNS + Stateful Operation of its own. A single server can support DNS + Queries, DNS Updates, and DNS Push Notifications (using DNS Stateful + Operations) on the same TCP port, and until the client has sent at + least one DNS Stateful Operations message, the server does not know what kind of client has connected to it. Once the client has - indicated willingness to use DNS Session Signaling operations by - sending one of its own, either side of the connection may then - initiate further Session Signaling operations at any time. + indicated willingness to use DNS Stateful Operations by sending one + of its own, either side of the connection may then initiate further + Stateful Operations at any time. A DNS Push Notification exchange begins with the client discovering the appropriate server, using the procedure described in Section 6.1, and then making a TLS/TCP connection to it. A typical DNS Push Notification client will immediately issue a DNS - Session Signaling Keepalive operation to request a session timeout or - keepalive interval longer than the the 15-second defaults, but this - is not required. A DNS Push Notification client MAY issue other - requests on the connection first, and only issue a DNS Session - Signaling Keepalive operation later if it determines that to be + Stateful Operations Keepalive operation to request a session timeout + or keepalive interval longer than the the 15-second defaults, but + this is not required. A DNS Push Notification client MAY issue other + requests on the connection first, and only issue a DNS Stateful + Operations Keepalive operation later if it determines that to be necessary. Once the connection is made, the client may then add and remove Push Notification subscriptions. In accordance with the current set of active subscriptions the server sends relevant asynchronous Push Notifications to the client. Note that a client MUST be prepared to receive (and silently ignore) Push Notifications for subscriptions it has previously removed, since there is no way to prevent the situation where a Push Notification is in flight from server to client while the client's UNSUBSCRIBE message cancelling that @@ -447,36 +447,36 @@ discovery process can be completed nearly instantaneously by the client, using only locally-stored cached data. 6.2. DNS Push Notification SUBSCRIBE After connecting, and requesting a longer idle timeout and/or keepalive interval if necessary, a DNS Push Notification client then indicates its desire to receive DNS Push Notifications for a given domain name by sending a SUBSCRIBE request over the established TLS connection to the server. A SUBSCRIBE request is encoded in a DNS - Session Signaling [SessSig] message. This specification defines a - DNS Session Signaling TLV for DNS Push Notification SUBSCRIBE - Requests/Responses (tentatively Session Signaling Type Code 0x40). + Stateful Operations [StatefulOp] message. This specification defines + a DNS Stateful Operations TLV for DNS Push Notification SUBSCRIBE + Requests/Responses (tentatively Stateful Operations Type Code 0x40). The entity that initiates a SUBSCRIBE request is by definition the client. A server should not send a SUBSCRIBE request over an existing connection from a client. If a server does send a SUBSCRIBE request over the connection initiated by a client, it is an error and the client should acknowledge the request with the error response RCODE NOTAUTH (Not Authoritative). 6.2.1. SUBSCRIBE Request - A SUBSCRIBE request message begins with the standard DNS Session - Signaling 12-byte header [SessSig], followed by the SUBSCRIBE TLV. A - SUBSCRIBE request message is illustrated below: + A SUBSCRIBE request message begins with the standard DNS Stateful + Operations 12-byte header [StatefulOp], followed by the SUBSCRIBE + TLV. A SUBSCRIBE request message is illustrated below: 1 1 1 1 1 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | MESSAGE ID | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |QR| Opcode | Z | RCODE | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | QDCOUNT (MUST BE ZERO) | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ @@ -502,25 +502,25 @@ Figure 1 The MESSAGE ID field MUST be set to a unique value, that the client is not using for any other active operation on this connection. For the purposes here, a MESSAGE ID is in use on this connection if the client has used it in a request for which it has not yet received a response, or if the client has used it for a subscription which it has not yet cancelled using UNSUBSCRIBE. In the SUBSCRIBE response the server MUST echo back the MESSAGE ID value unchanged. - The other header fields MUST be set as described in the DNS Session - Signaling specification [SessSig]. The DNS Opcode is the Session - Signaling Opcode (tentatively 6). The four count fields MUST be - zero, and the corresponding four sections MUST be empty (i.e., - absent). + The other header fields MUST be set as described in the DNS Stateful + Operations specification [StatefulOp]. The DNS Opcode is the + Stateful Operations Opcode (tentatively 6). The four count fields + MUST be zero, and the corresponding four sections MUST be empty + (i.e., absent). The SSOP-TYPE is SUBSCRIBE (tentatively 0x40). The SSOP-LENGTH is the length of the SSOP-DATA that follows, which specifies the name, type, and class of the record(s) being sought. The SSOP-DATA for a SUBSCRIBE request MUST contain exactly one question. The SSOP-DATA for a SUBSCRIBE request has no QDCOUNT field to specify more than one question. Since SUBSCRIBE requests are sent over TCP, multiple SUBSCRIBE request messages can be concatenated in a single TCP stream and packed efficiently into TCP segments. @@ -569,48 +569,48 @@ interpreted to mean "ALL", not "ANY". After accepting a subscription where one or both of TYPE or CLASS are 255, the server MUST send Push Notification Updates for ALL record changes that match the subscription, not just some of them. 6.2.2. SUBSCRIBE Response Each SUBSCRIBE request generates exactly one SUBSCRIBE response from the server. - A SUBSCRIBE response message begins with the standard DNS Session - Signaling 12-byte header [SessSig], possibly followed by one or more - optional Modifier TLVs, such as a Retry Delay Modifier TLV. + A SUBSCRIBE response message begins with the standard DNS Stateful + Operations 12-byte header [StatefulOp], possibly followed by one or + more optional Modifier TLVs, such as a Retry Delay Modifier TLV. The MESSAGE ID field MUST echo the value given in the ID field of the SUBSCRIBE request. This is how the client knows which request is being responded to. - A SUBSCRIBE response message MUST NOT contain a Session Signaling - Operation TLV. The Session Signaling Operation TLV is NOT copied + A SUBSCRIBE response message MUST NOT contain a Stateful Operations + Operation TLV. The Stateful Operations Operation TLV is NOT copied from the SUBSCRIBE request. In the SUBSCRIBE response the RCODE indicates whether or not the subscription was accepted. Supported RCODEs are as follows: +------------+-------+----------------------------------------------+ | Mnemonic | Value | Description | +------------+-------+----------------------------------------------+ | NOERROR | 0 | SUBSCRIBE successful. | | FORMERR | 1 | Server failed to process request due to a | | | | malformed request. | | SERVFAIL | 2 | Server failed to process request due to a | | | | problem with the server. | | NXDOMAIN | 3 | NOT APPLICABLE. DNS Push Notification | | | | servers MUST NOT return NXDOMAIN errors in | | | | response to SUBSCRIBE requests. | - | NOTIMP | 4 | Server does not recognize DNS Session | - | | | Signaling Opcode. | + | NOTIMP | 4 | Server does not recognize DNS Stateful | + | | | Operations Opcode. | | REFUSED | 5 | Server refuses to process request for policy | | | | or security reasons. | | NOTAUTH | 9 | Server is not authoritative for the | | | | requested name. | | SSOPNOTIMP | 11 | SUBSCRIBE operation not supported. | +------------+-------+----------------------------------------------+ SUBSCRIBE Response codes This document specifies only these RCODE values for SUBSCRIBE @@ -621,38 +621,38 @@ value. If the server sends a nonzero RCODE in the SUBSCRIBE response, either the client is (at least partially) misconfigured, the server resources are exhausted, or there is some other unknown failure on the server. In any case, the client shouldn't retry the subscription right away. Either end can terminate the connection, but the client may want to try this subscription again, or it may have other successful subscriptions that it doesn't want to abandon. If the server sends a nonzero RCODE then it SHOULD append a Retry Delay - Modifier TLV [SessSig] to the response specifying a delay before the - client attempts this operation again. Recommended values for the + Modifier TLV [StatefulOp] to the response specifying a delay before + the client attempts this operation again. Recommended values for the delay for different RCODE values are given below: For RCODE = 1 (FORMERR) the delay may be any value selected by the implementer. A value of five minutes is RECOMMENDED, to reduce the risk of high load from defective clients. For RCODE = 2 (SERVFAIL) the delay should be chosen according to the level of server overload and the anticipated duration of that overload. By default, a value of one minute is RECOMMENDED. If a more serious server failure occurs, the delay may be longer in accordance with the specific problem encountered. For RCODE = 4 (NOTIMP), which occurs on a server that doesn't - implement DNS Session Signaling [SessSig], it is unlikely that the - server will begin supporting DNS Session Signaling in the next few - minutes, so the retry delay SHOULD be one hour. + implement DNS Stateful Operations [StatefulOp], it is unlikely + that the server will begin supporting DNS Stateful Operations in + the next few minutes, so the retry delay SHOULD be one hour. For RCODE = 5 (REFUSED), which occurs on a server that implements DNS Push Notifications, but is currently configured to disallow DNS Push Notifications, the retry delay may be any value selected by the implementer and/or configured by the operator. This is a misconfiguration, since this server is listed in a "_dns-push-tls._tcp." SRV record, but the server itself is not currently configured to support DNS Push Notifications. Since it is possible that the misconfiguration may be repaired at any time, the retry delay should not be set too high. By default, a @@ -681,37 +681,37 @@ For RCODE = 9 (NOTAUTH), the time delay applies to requests for other names falling within the same zone. Requests for names falling within other zones are not subject to the delay. For all other RCODEs the time delay applies to all subsequent requests to this server. After sending an error response the server MAY allow the connection to remain open, or MAY send a DNS Push Notification Retry Delay Operation TLV instructing the client to close the TCP connection, as - described in the DNS Session Signaling specification [SessSig]. + described in the DNS Stateful Operations specification [StatefulOp]. Clients MUST correctly handle both cases. 6.3. DNS Push Notification Updates Once a subscription has been successfully established, the server generates PUSH messages to send to the client as appropriate. In the case that the answer set was non-empty at the moment the subscription was established, an initial PUSH message will be sent immediately following the SUBSCRIBE Response. Subsequent changes to the answer set are then communicated to the client in subsequent PUSH messages. 6.3.1. PUSH Message - A PUSH message begins with the standard DNS Session Signaling 12-byte - header [SessSig], followed by the PUSH TLV. A PUSH message is - illustrated below: + A PUSH message begins with the standard DNS Stateful Operations + 12-byte header [StatefulOp], followed by the PUSH TLV. A PUSH + message is illustrated below: 1 1 1 1 1 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | MESSAGE ID | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |QR| Opcode | Z | RCODE | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | QDCOUNT (MUST BE ZERO) | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ @@ -749,38 +749,38 @@ Figure 2 The MESSAGE ID field MUST be set to a unique value, that the server is not currently using for any other active outgoing request that it has sent on this connection. The MESSAGE ID in the outgoing PUSH message is selected by the server and has no relationship to the MESSAGE ID in any of the client subscriptions it may relate to. In the PUSH response the client MUST echo back the MESSAGE ID value unchanged. - The other header fields MUST be set as described in the DNS Session - Signaling specification [SessSig]. The DNS Opcode is the Session - Signaling Opcode (tentatively 6). The four count fields MUST be - zero, and the corresponding four sections MUST be empty (i.e., - absent). + The other header fields MUST be set as described in the DNS Stateful + Operations specification [StatefulOp]. The DNS Opcode is the + Stateful Operations Opcode (tentatively 6). The four count fields + MUST be zero, and the corresponding four sections MUST be empty + (i.e., absent). The SSOP-TYPE is PUSH (tentatively 0x41). The SSOP-LENGTH is the length of the SSOP-DATA that follows, which specifies the changes being communicated. The SSOP-DATA contains one or more Update records. A PUSH Message MUST contain at least one Update record. If a PUSH Message is received that contains no Update records, this is a fatal error, and the receiver MUST immediately terminate the connection with a TCP RST (or equivalent for other protocols). The Update records are formatted in the customary way for Resource Records in DNS messages with the stipulation that DNS name compression is not permitted in - DNS Session Signaling TLVs. Update records in a PUSH Message are + DNS Stateful Operations TLVs. Update records in a PUSH Message are interpreted according to the same rules as for DNS Update [RFC2136] messages, namely: Delete all RRsets from a name: TTL=0, CLASS=ANY, RDLENGTH=0, TYPE=ANY. Delete an RRset from a name: TTL=0, CLASS=ANY, RDLENGTH=0; TYPE specifies the RRset being deleted. @@ -843,55 +843,56 @@ that the record is still there. Once a subscription is cancelled (individually, or as a result of the TCP connection being closed) record aging resumes and records are removed from the local cache when their TTL reaches zero. 6.3.2. PUSH Response Each PUSH message generates exactly one PUSH response from the receiver. - A PUSH response message begins with the standard DNS Session - Signaling 12-byte header [SessSig], possibly followed by one or more - optional Modifier TLVs. + A PUSH response message begins with the standard DNS Stateful + Operations 12-byte header [StatefulOp], possibly followed by one or + more optional Modifier TLVs. The MESSAGE ID field MUST echo the value given in the ID field of the PUSH message. - A PUSH response message MUST NOT contain a Session Signaling - Operation TLV. The Session Signaling Operation TLV is NOT copied + A PUSH response message MUST NOT contain a Stateful Operations + Operation TLV. The Stateful Operations Operation TLV is NOT copied from the PUSH message. In a PUSH response the RCODE MUST be zero. Receiving a PUSH response with a nonzero RCODE is a fatal error, and the receiver MUST immediately terminate the connection with a TCP RST (or equivalent for other protocols). 6.4. DNS Push Notification UNSUBSCRIBE To cancel an individual subscription without closing the entire connection, the client sends an UNSUBSCRIBE message over the established TCP connection to the server. The UNSUBSCRIBE message is - encoded in a DNS Session Signaling [SessSig] message. This - specification defines a DNS Session Signaling TLV for DNS Push - Notification UNSUBSCRIBE Requests/Responses (tentatively Session - Signaling Type Code 0x42). + encoded in a DNS Stateful Operations [StatefulOp] message. This + specification defines a DNS Stateful Operations TLV for DNS Push + Notification UNSUBSCRIBE Requests/Responses (tentatively Stateful + Operations Type Code 0x42). A server MUST NOT initiate an UNSUBSCRIBE request. If a server does send a UNSUBSCRIBE request over the connection initiated by a client, it is an error and the client should acknowledge the request with the error response RCODE NOTAUTH (Not Authoritative). 6.4.1. UNSUBSCRIBE Request - An UNSUBSCRIBE request message begins with the standard DNS Session - Signaling 12-byte header [SessSig], followed by the UNSUBSCRIBE TLV. + An UNSUBSCRIBE request message begins with the standard DNS Stateful + Operations 12-byte header [StatefulOp], followed by the UNSUBSCRIBE + TLV. 1 1 1 1 1 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | MESSAGE ID | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |QR| Opcode | Z | RCODE | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | QDCOUNT (MUST BE ZERO) | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ @@ -931,44 +932,44 @@ yet unacknowledged SUBSCRIBE request, and the SUBSCRIBE request is subsequently unsuccessful for some reason, then when the UNSUBSCRIBE request is eventually processed it will be an UNSUBSCRIBE request for a nonexistent subscription, which will result NXDOMAIN response. 6.4.2. UNSUBSCRIBE Response Each UNSUBSCRIBE request generates exactly one UNSUBSCRIBE response from the server. - An UNSUBSCRIBE response message begins with the standard DNS Session - Signaling 12-byte header [SessSig], possibly followed by one or more - optional Modifier TLVs, such as a Retry Delay Modifier TLV. + An UNSUBSCRIBE response message begins with the standard DNS Stateful + Operations 12-byte header [StatefulOp], possibly followed by one or + more optional Modifier TLVs, such as a Retry Delay Modifier TLV. The MESSAGE ID field MUST echo the value given in the ID field of the UNSUBSCRIBE request. This is how the client knows which request is being responded to. - An UNSUBSCRIBE response message MUST NOT contain a Session Signaling - Operation TLV. The Session Signaling Operation TLV is NOT copied - from the UNSUBSCRIBE request. + An UNSUBSCRIBE response message MUST NOT contain a Stateful + Operations Operation TLV. The Stateful Operations Operation TLV is + NOT copied from the UNSUBSCRIBE request. In the UNSUBSCRIBE response the RCODE indicates whether or not the unsubscribe request was successful. Supported RCODEs are as follows: +------------+-------+----------------------------------------------+ | Mnemonic | Value | Description | +------------+-------+----------------------------------------------+ | NOERROR | 0 | UNSUBSCRIBE successful. | | FORMERR | 1 | Server failed to process request due to a | | | | malformed request. | | NXDOMAIN | 3 | Specified subscription does not exist. | - | NOTIMP | 4 | Server does not recognize DNS Session | - | | | Signaling Opcode. | + | NOTIMP | 4 | Server does not recognize DNS Stateful | + | | | Operations Opcode. | | SSOPNOTIMP | 11 | UNSUBSCRIBE operation not supported. | +------------+-------+----------------------------------------------+ UNSUBSCRIBE Response codes This document specifies only these RCODE values for UNSUBSCRIBE Responses. Servers sending UNSUBSCRIBE Responses SHOULD use one of these values. However, future circumstances may create situations where other RCODE values are appropriate in UNSUBSCRIBE Responses, so clients MUST be prepared to accept UNSUBSCRIBE Responses with any @@ -982,35 +983,35 @@ Nonzero RCODE values signal some kind of error. RCODE value FORMERR indicates a message format error. RCODE value NXDOMAIN indicates a MESSAGE ID that does not correspond to any active subscription. RCODE values NOTIMP and SSOPNOTIMP should not occur in practice. - A server would only generate NOTIMP if it did not support Session - Signaling, and if the server does not support Session Signaling then - it should not be possible for a client to have an active subscription - to cancel. + A server would only generate NOTIMP if it did not support Stateful + Operations, and if the server does not support Stateful Operations + then it should not be possible for a client to have an active + subscription to cancel. Similarly, a server would only generate SSOPNOTIMP if it did not support Push Notifications, and if the server does not support Push Notifications then it should not be possible for a client to have an active subscription to cancel. Nonzero RCODE values other than NXDOMAIN indicate a serious problem with the client. After sending an error response other than - NXDOMAIN, the server SHOULD send a DNS Session Signaling Retry Delay - Operation TLV and then close the TCP connection, as described in the - DNS Session Signaling specification [SessSig]. + NXDOMAIN, the server SHOULD send a DNS Stateful Operations Retry + Delay Operation TLV and then close the TCP connection, as described + in the DNS Stateful Operations specification [StatefulOp]. 6.5. DNS Push Notification RECONFIRM Sometimes, particularly when used with a Discovery Proxy [DisProx], a DNS Zone may contain stale data. When a client encounters data that it believe may be stale (e.g., an SRV record referencing a target host+port that is not responding to connection requests) the client can send a RECONFIRM request to ask the server to re-verify that the data is still valid. For a Discovery Proxy, this causes it to issue new Multicast DNS requests to ascertain whether the target device is @@ -1025,23 +1026,23 @@ If, after receiving a valid RECONFIRM request, the server determines that the disputed records are in fact no longer valid, then subsequent DNS PUSH Messages will be generated to inform interested clients. Thus, one client discovering that a previously-advertised device (like a network printer) is no longer present has the side effect of informing all other interested clients that the device in question is now gone. 6.5.1. RECONFIRM Request - A RECONFIRM request message begins with the standard DNS Session - Signaling 12-byte header [SessSig], followed by the RECONFIRM TLV. A - RECONFIRM request message is illustrated below: + A RECONFIRM request message begins with the standard DNS Stateful + Operations 12-byte header [StatefulOp], followed by the RECONFIRM + TLV. A RECONFIRM request message is illustrated below: 1 1 1 1 1 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | MESSAGE ID | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |QR| Opcode | Z | RCODE | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | QDCOUNT (MUST BE ZERO) | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ @@ -1069,25 +1070,25 @@ Figure 4 The MESSAGE ID field MUST be set to a unique value, that the client is not using for any other active operation on this connection. For the purposes here, a MESSAGE ID is in use on this connection if the client has used it in a request for which it has not yet received a response, or if the client has used it for a subscription which it has not yet cancelled using UNSUBSCRIBE. In the RECONFIRM response the server MUST echo back the MESSAGE ID value unchanged. - The other header fields MUST be set as described in the DNS Session - Signaling specification [SessSig]. The DNS Opcode is the Session - Signaling Opcode (tentatively 6). The four count fields MUST be - zero, and the corresponding four sections MUST be empty (i.e., - absent). + The other header fields MUST be set as described in the DNS Stateful + Operations specification [StatefulOp]. The DNS Opcode is the + Stateful Operations Opcode (tentatively 6). The four count fields + MUST be zero, and the corresponding four sections MUST be empty + (i.e., absent). The SSOP-TYPE is RECONFIRM (tentatively 0x43). The SSOP-LENGTH is the length of the data that follows, which specifies the name, type, class, and content of the record being disputed. The SSOP-DATA for a RECONFIRM request MUST contain exactly one record. The SSOP-DATA for a RECONFIRM request has no count field to specify more than one record. Since RECONFIRM requests are sent over TCP, multiple RECONFIRM request messages can be concatenated in a single TCP stream and packed efficiently into TCP segments. @@ -1100,48 +1101,48 @@ the zone, and nothing else. Aliasing is not supported. That is, a CNAME in a RECONFIRM message matches only a literal CNAME record in the zone, and nothing else. 6.5.2. RECONFIRM Response Each RECONFIRM request generates exactly one RECONFIRM response from the server. - A RECONFIRM response message begins with the standard DNS Session - Signaling 12-byte header [SessSig], possibly followed by one or more - optional Modifier TLVs, such as a Retry Delay Modifier TLV. + A RECONFIRM response message begins with the standard DNS Stateful + Operations 12-byte header [StatefulOp], possibly followed by one or + more optional Modifier TLVs, such as a Retry Delay Modifier TLV. The MESSAGE ID field MUST echo the value given in the ID field of the RECONFIRM request. This is how the client knows which request is being responded to. - A RECONFIRM response message MUST NOT contain a Session Signaling - Operation TLV. The Session Signaling Operation TLV is NOT copied + A RECONFIRM response message MUST NOT contain a Stateful Operations + Operation TLV. The Stateful Operations Operation TLV is NOT copied from the RECONFIRM request. In the RECONFIRM response the RCODE confirms receipt of the reconfirmation request. Supported RCODEs are as follows: +------------+-------+----------------------------------------------+ | Mnemonic | Value | Description | +------------+-------+----------------------------------------------+ | NOERROR | 0 | RECONFIRM accepted. | | FORMERR | 1 | Server failed to process request due to a | | | | malformed request. | | SERVFAIL | 2 | Server failed to process request due to a | | | | problem with the server. | | NXDOMAIN | 3 | NOT APPLICABLE. DNS Push Notification | | | | servers MUST NOT return NXDOMAIN errors in | | | | response to RECONFIRM requests. | - | NOTIMP | 4 | Server does not recognize DNS Session | - | | | Signaling Opcode. | + | NOTIMP | 4 | Server does not recognize DNS Stateful | + | | | Operations Opcode. | | REFUSED | 5 | Server refuses to process request for policy | | | | or security reasons. | | NOTAUTH | 9 | Server is not authoritative for the | | | | requested name. | | SSOPNOTIMP | 11 | RECONFIRM operation not supported. | +------------+-------+----------------------------------------------+ RECONFIRM Response codes This document specifies only these RCODE values for RECONFIRM @@ -1153,64 +1154,64 @@ Nonzero RCODE values signal some kind of error. RCODE value FORMERR indicates a message format error, for example TYPE or CLASS being ANY (255). RCODE value SERVFAIL indicates that the server has exhausted its resources or other serious problem occurred. RCODE values NOTIMP indicates that the server does not support - Session Signaling, and Session Signaling is required for RECONFIRM - requests. + Stateful Operations, and Stateful Operations is required for + RECONFIRM requests. RCODE value REFUSED indicates that the server supports RECONFIRM requests but is currently not configured to accept them from this client. RCODE value NOTAUTH indicates that the server is not authoritative for the requested name, and can do nothing to remedy the apparent error. Note that there may be future cases in which a server is able to pass on the RECONFIRM request to the ultimate source of the information, and in these cases the server should return NOERROR. RCODE value SSOPNOTIMP indicates that the server does not support RECONFIRM requests. Nonzero RCODE values SERVFAIL, REFUSED and SSOPNOTIMP are benign from the client's point of view. The client may log them to aid in debugging, but otherwise they require no special action. Nonzero RCODE values other than these three indicate a serious problem with the client. After sending an error response other than - one of these three, the server SHOULD send a DNS Session Signaling + one of these three, the server SHOULD send a DNS Stateful Operations Retry Delay Operation TLV and then close the TCP connection, as - described in the DNS Session Signaling specification [SessSig]. + described in the DNS Stateful Operations specification [StatefulOp]. 6.6. Client-Initiated Termination An individual subscription is terminated by sending an UNSUBSCRIBE TLV for that specific subscription, or all subscriptions can be cancelled at once by the client closing the connection. When a client terminates an individual subscription (via UNSUBSCRIBE) or all subscriptions on that connection (by closing the connection) it is signaling to the server that it is longer interested in receiving those particular updates. It is informing the server that the server may release any state information it has been keeping with regards to these particular subscriptions. After terminating its last subscription on a connection via UNSUBSCRIBE, a client MAY close the connection immediately, or it may keep it open if it anticipates performing further operations on that connection in the future. If a client wishes to keep an idle connection open, it MUST respect the maximum idle time required by - the server [SessSig]. + the server [StatefulOp]. If a client plans to terminate one or more subscriptions on a connection and doesn't intend to keep that connection open, then as an efficiency optimization it MAY instead choose to simply close the connection, which implicitly terminates all subscriptions on that connection. This may occur because the client computer is being shut down, is going to sleep, the application requiring the subscriptions has terminated, or simply because the last active subscription on that connection has been cancelled. @@ -1313,214 +1314,216 @@ up more quickly, but the client will still have to recreate any desired subscriptions. 8. IANA Considerations This document defines the service name: "_dns-push-tls._tcp". It is only applicable for the TCP protocol. This name is to be published in the IANA Service Name Registry [RFC6335][SN]. - This document defines four DNS Session Signaling TLV types: SUBSCRIBE - with (tentative) value 0x40 (64), PUSH with (tentative) value 0x41 - (65), UNSUBSCRIBE with (tentative) value 0x42 (66), and RECONFIRM - with (tentative) value 0x43 (67). + This document defines four DNS Stateful Operations TLV types: + SUBSCRIBE with (tentative) value 0x40 (64), PUSH with (tentative) + value 0x41 (65), UNSUBSCRIBE with (tentative) value 0x42 (66), and + RECONFIRM with (tentative) value 0x43 (67). 9. Acknowledgements The authors would like to thank Kiren Sekar and Marc Krochmal for previous work completed in this field. This draft has been improved due to comments from Ran Atkinson, Tim Chown, Mark Delany, Ralph Droms, Bernie Volz, Jan Komissar, Manju Shankar Rao, Markus Stenberg, Dave Thaler, Soraia Zlatkovic, Sara Dickinson, and Andrew Sullivan. 10. References 10.1. Normative References [I-D.ietf-tls-tls13] Rescorla, E., "The Transport Layer Security (TLS) Protocol - Version 1.3", draft-ietf-tls-tls13-20 (work in progress), - April 2017. + Version 1.3", draft-ietf-tls-tls13-21 (work in progress), + July 2017. [RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, - DOI 10.17487/RFC0768, August 1980, - . + DOI 10.17487/RFC0768, August 1980, . [RFC0793] Postel, J., "Transmission Control Protocol", STD 7, RFC 793, DOI 10.17487/RFC0793, September 1981, - . + . [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, - . + . [RFC1035] Mockapetris, P., "Domain names - implementation and specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, - November 1987, . + November 1987, . [RFC1123] Braden, R., Ed., "Requirements for Internet Hosts - Application and Support", STD 3, RFC 1123, - DOI 10.17487/RFC1123, October 1989, - . + DOI 10.17487/RFC1123, October 1989, . [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, - DOI 10.17487/RFC2119, March 1997, - . + DOI 10.17487/RFC2119, March 1997, . [RFC2136] Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound, "Dynamic Updates in the Domain Name System (DNS UPDATE)", RFC 2136, DOI 10.17487/RFC2136, April 1997, - . + . [RFC2782] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for specifying the location of services (DNS SRV)", RFC 2782, - DOI 10.17487/RFC2782, February 2000, - . + DOI 10.17487/RFC2782, February 2000, . [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, - DOI 10.17487/RFC5246, August 2008, - . + DOI 10.17487/RFC5246, August 2008, . [RFC6066] Eastlake 3rd, D., "Transport Layer Security (TLS) Extensions: Extension Definitions", RFC 6066, - DOI 10.17487/RFC6066, January 2011, - . + DOI 10.17487/RFC6066, January 2011, . [RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S. Cheshire, "Internet Assigned Numbers Authority (IANA) Procedures for the Management of the Service Name and Transport Protocol Port Number Registry", BCP 165, RFC 6335, DOI 10.17487/RFC6335, August 2011, - . + . [RFC6895] Eastlake 3rd, D., "Domain Name System (DNS) IANA Considerations", BCP 42, RFC 6895, DOI 10.17487/RFC6895, - April 2013, . + April 2013, . [RFC7673] Finch, T., Miller, M., and P. Saint-Andre, "Using DNS- Based Authentication of Named Entities (DANE) TLSA Records with SRV Records", RFC 7673, DOI 10.17487/RFC7673, October - 2015, . + 2015, . [RFC7766] Dickinson, J., Dickinson, S., Bellis, R., Mankin, A., and D. Wessels, "DNS Transport over TCP - Implementation Requirements", RFC 7766, DOI 10.17487/RFC7766, March 2016, - . - - [SessSig] Bellis, R., Cheshire, S., Dickinson, J., Dickinson, S., - Mankin, A., and T. Pusateri, "DNS Session Signaling", - draft-ietf-dnsop-session-signal-02 (work in progress), - March 2017. + . [SN] "Service Name and Transport Protocol Port Number Registry", . + [StatefulOp] + Bellis, R., Cheshire, S., Dickinson, J., Dickinson, S., + Mankin, A., and T. Pusateri, "DNS Stateful Operations", + draft-ietf-dnsop-session-signal-04 (work in progress), + September 2017. + 10.2. Informative References [DisProx] Cheshire, S., "Hybrid Unicast/Multicast DNS-Based Service - Discovery", draft-ietf-dnssd-hybrid-06 (work in progress), - March 2017. + Discovery", draft-ietf-dnssd-hybrid-07 (work in progress), + September 2017. [I-D.dukkipati-tcpm-tcp-loss-probe] Dukkipati, N., Cardwell, N., Cheng, Y., and M. Mathis, "Tail Loss Probe (TLP): An Algorithm for Fast Recovery of Tail Losses", draft-dukkipati-tcpm-tcp-loss-probe-01 (work in progress), February 2013. [I-D.ietf-dprive-dtls-and-tls-profiles] Dickinson, S., Gillmor, D., and T. Reddy, "Usage and (D)TLS Profiles for DNS-over-(D)TLS", draft-ietf-dprive- - dtls-and-tls-profiles-10 (work in progress), June 2017. + dtls-and-tls-profiles-11 (work in progress), September + 2017. [I-D.sekar-dns-llq] Sekar, K., "DNS Long-Lived Queries", draft-sekar-dns- llq-01 (work in progress), August 2006. [IPJ.9-4-TCPSYN] Eddy, W., "Defenses Against TCP SYN Flooding Attacks", The Internet Protocol Journal, Cisco Systems, Volume 9, Number 4, December 2006. [obs] "Observer Pattern", . [RFC2308] Andrews, M., "Negative Caching of DNS Queries (DNS NCACHE)", RFC 2308, DOI 10.17487/RFC2308, March 1998, - . + . [RFC4287] Nottingham, M., Ed. and R. Sayre, Ed., "The Atom Syndication Format", RFC 4287, DOI 10.17487/RFC4287, - December 2005, . + December 2005, . [RFC4953] Touch, J., "Defending TCP Against Spoofing Attacks", RFC 4953, DOI 10.17487/RFC4953, July 2007, - . + . [RFC5077] Salowey, J., Zhou, H., Eronen, P., and H. Tschofenig, "Transport Layer Security (TLS) Session Resumption without Server-Side State", RFC 5077, DOI 10.17487/RFC5077, - January 2008, . + January 2008, . [RFC6281] Cheshire, S., Zhu, Z., Wakikawa, R., and L. Zhang, "Understanding Apple's Back to My Mac (BTMM) Service", RFC 6281, DOI 10.17487/RFC6281, June 2011, - . + . [RFC6762] Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762, - DOI 10.17487/RFC6762, February 2013, - . + DOI 10.17487/RFC6762, February 2013, . [RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013, - . + . [RFC6824] Ford, A., Raiciu, C., Handley, M., and O. Bonaventure, "TCP Extensions for Multipath Operation with Multiple Addresses", RFC 6824, DOI 10.17487/RFC6824, January 2013, - . + . [RFC7413] Cheng, Y., Chu, J., Radhakrishnan, S., and A. Jain, "TCP Fast Open", RFC 7413, DOI 10.17487/RFC7413, December 2014, - . + . [RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre, "Recommendations for Secure Use of Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May - 2015, . + 2015, . [RFC7719] Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS Terminology", RFC 7719, DOI 10.17487/RFC7719, December - 2015, . + 2015, . [RFC7858] Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D., and P. Hoffman, "Specification for DNS over Transport Layer Security (TLS)", RFC 7858, DOI 10.17487/RFC7858, May - 2016, . + 2016, . [XEP0060] Millard, P., Saint-Andre, P., and R. Meijer, "Publish- Subscribe", XSF XEP 0060, July 2010. Authors' Addresses Tom Pusateri - Seeking affiliation - Hilton Head Island, SC + Unaffiliated + Raleigh, NC 27608 USA - Phone: +1 843 473 7394 + Phone: +1 919 867 1330 Email: pusateri@bangj.com Stuart Cheshire Apple Inc. 1 Infinite Loop Cupertino, CA 95014 USA Phone: +1 408 974 3207 Email: cheshire@apple.com