draft-ietf-dnssd-push-12.txt		draft-ietf-dnssd-push-13.txt
	Internet Engineering Task Force T. Pusateri		Internet Engineering Task Force T. Pusateri
	Internet-Draft Seeking affiliation		Internet-Draft Unaffiliated
	Intended status: Standards Track S. Cheshire		Intended status: Standards Track S. Cheshire
	Expires: January 3, 2018 Apple Inc.		Expires: May 2, 2018 Apple Inc.
	July 2, 2017		October 29, 2017
	DNS Push Notifications		DNS Push Notifications
	draft-ietf-dnssd-push-12		draft-ietf-dnssd-push-13
	Abstract		Abstract
	The Domain Name System (DNS) was designed to return matching records		The Domain Name System (DNS) was designed to return matching records
	efficiently for queries for data that is relatively static. When		efficiently for queries for data that is relatively static. When
	those records change frequently, DNS is still efficient at returning		those records change frequently, DNS is still efficient at returning
	the updated results when polled, as long as the polling rate is not		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		too high. But there exists no mechanism for a client to be
	asynchronously notified when these changes occur. This document		asynchronously notified when these changes occur. This document
	defines a mechanism for a client to be notified of such changes to		defines a mechanism for a client to be notified of such changes to
	skipping to change at page 1, line 38 ¶		skipping to change at page 1, line 38 ¶
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at http://datatracker.ietf.org/drafts/current/.		Drafts is at http://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		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 Notice
	Copyright (c) 2017 IETF Trust and the persons identified as the		Copyright (c) 2017 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	skipping to change at page 6, line 9 ¶		skipping to change at page 6, line 9 ¶
	"Print" button again when they wake their phone up.		"Print" button again when they wake their phone up.
	A DNS Push Notification client must not routinely keep a DNS Push		A DNS Push Notification client must not routinely keep a DNS Push
	Notification subscription active 24 hours a day, 7 days a week, just		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 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		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		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		that there is no need to pre-load a "warm" list in memory just in
	case it might be needed later.		case it might be needed later.
	Generally, as described in the DNS Session Signaling specification		Generally, as described in the DNS Stateful Operations specification
	[SessSig], a client must not keep a connection to a server open		[StatefulOp], a client must not keep a connection to a server open
	indefinitely if it has no subscriptions (or other operations) active		indefinitely if it has no subscriptions (or other operations) active
	on that connection. A client MAY close a connection as soon as it		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		becomes idle, and then if needed in the future, open a new connection
	when required. Alternatively, a client MAY speculatively keep an		when required. Alternatively, a client MAY speculatively keep an
	idle connection open for some time, subject to the constraint that it		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		MUST NOT keep a connection open that has been idle for more than the
	session's idle timeout (15 seconds by default).		session's idle timeout (15 seconds by default).
	4. Transport		4. Transport
	skipping to change at page 8, line 8 ¶		skipping to change at page 8, line 8 ¶
	connections to alternate DNS servers that support DNS Push		connections to alternate DNS servers that support DNS Push
	Notifications for the zone and distribute subscriptions at its		Notifications for the zone and distribute subscriptions at its
	discretion. In this way, both clients and servers can react to		discretion. In this way, both clients and servers can react to
	resource constraints. Token bucket rate limiting schemes are also		resource constraints. Token bucket rate limiting schemes are also
	effective in providing fairness by a server across numerous client		effective in providing fairness by a server across numerous client
	requests.		requests.
	6. Protocol Operation		6. Protocol Operation
	The DNS Push Notification protocol is a session-oriented protocol,		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		For details of the DNS Stateful Operations message format refer to
	DNS Session Signaling specification [SessSig]. Those details are not		the DNS Stateful Operations specification [StatefulOp]. Those
	repeated here.		details are not repeated here.
	DNS Push Notification clients and servers MUST support DNS Session		DNS Push Notification clients and servers MUST support DNS Stateful
	Signaling, but the server SHOULD NOT issue any DNS Session Signaling		Operations, but the server SHOULD NOT issue any DNS Stateful
	operations until after the client has first initiated a DNS Session		Operations messages until after the client has first initiated a DNS
	Signaling operation of its own. A single server can support DNS		Stateful Operation of its own. A single server can support DNS
	Queries, DNS Updates, and DNS Push Notifications (using DNS Session		Queries, DNS Updates, and DNS Push Notifications (using DNS Stateful
	Signaling) on the same TCP port, and until the client has sent at		Operations) on the same TCP port, and until the client has sent at
	least one DNS Session Signaling operation the server does not know		least one DNS Stateful Operations message, the server does not know
	what kind of client has connected to it. Once the client has		what kind of client has connected to it. Once the client has
	indicated willingness to use DNS Session Signaling operations by		indicated willingness to use DNS Stateful Operations by sending one
	sending one of its own, either side of the connection may then		of its own, either side of the connection may then initiate further
	initiate further Session Signaling operations at any time.		Stateful Operations at any time.
	A DNS Push Notification exchange begins with the client discovering		A DNS Push Notification exchange begins with the client discovering
	the appropriate server, using the procedure described in Section 6.1,		the appropriate server, using the procedure described in Section 6.1,
	and then making a TLS/TCP connection to it.		and then making a TLS/TCP connection to it.
	A typical DNS Push Notification client will immediately issue a DNS		A typical DNS Push Notification client will immediately issue a DNS
	Session Signaling Keepalive operation to request a session timeout or		Stateful Operations Keepalive operation to request a session timeout
	keepalive interval longer than the the 15-second defaults, but this		or keepalive interval longer than the the 15-second defaults, but
	is not required. A DNS Push Notification client MAY issue other		this is not required. A DNS Push Notification client MAY issue other
	requests on the connection first, and only issue a DNS Session		requests on the connection first, and only issue a DNS Stateful
	Signaling Keepalive operation later if it determines that to be		Operations Keepalive operation later if it determines that to be
	necessary.		necessary.
	Once the connection is made, the client may then add and remove Push		Once the connection is made, the client may then add and remove Push
	Notification subscriptions. In accordance with the current set of		Notification subscriptions. In accordance with the current set of
	active subscriptions the server sends relevant asynchronous Push		active subscriptions the server sends relevant asynchronous Push
	Notifications to the client. Note that a client MUST be prepared to		Notifications to the client. Note that a client MUST be prepared to
	receive (and silently ignore) Push Notifications for subscriptions it		receive (and silently ignore) Push Notifications for subscriptions it
	has previously removed, since there is no way to prevent the		has previously removed, since there is no way to prevent the
	situation where a Push Notification is in flight from server to		situation where a Push Notification is in flight from server to
	client while the client's UNSUBSCRIBE message cancelling that		client while the client's UNSUBSCRIBE message cancelling that
	skipping to change at page 12, line 12 ¶		skipping to change at page 12, line 12 ¶
	discovery process can be completed nearly instantaneously by the		discovery process can be completed nearly instantaneously by the
	client, using only locally-stored cached data.		client, using only locally-stored cached data.
	6.2. DNS Push Notification SUBSCRIBE		6.2. DNS Push Notification SUBSCRIBE
	After connecting, and requesting a longer idle timeout and/or		After connecting, and requesting a longer idle timeout and/or
	keepalive interval if necessary, a DNS Push Notification client then		keepalive interval if necessary, a DNS Push Notification client then
	indicates its desire to receive DNS Push Notifications for a given		indicates its desire to receive DNS Push Notifications for a given
	domain name by sending a SUBSCRIBE request over the established TLS		domain name by sending a SUBSCRIBE request over the established TLS
	connection to the server. A SUBSCRIBE request is encoded in a DNS		connection to the server. A SUBSCRIBE request is encoded in a DNS
	Session Signaling [SessSig] message. This specification defines a		Stateful Operations [StatefulOp] message. This specification defines
	DNS Session Signaling TLV for DNS Push Notification SUBSCRIBE		a DNS Stateful Operations TLV for DNS Push Notification SUBSCRIBE
	Requests/Responses (tentatively Session Signaling Type Code 0x40).		Requests/Responses (tentatively Stateful Operations Type Code 0x40).
	The entity that initiates a SUBSCRIBE request is by definition the		The entity that initiates a SUBSCRIBE request is by definition the
	client. A server should not send a SUBSCRIBE request over an		client. A server should not send a SUBSCRIBE request over an
	existing connection from a client. If a server does send a SUBSCRIBE		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		request over the connection initiated by a client, it is an error and
	the client should acknowledge the request with the error response		the client should acknowledge the request with the error response
	RCODE NOTAUTH (Not Authoritative).		RCODE NOTAUTH (Not Authoritative).
	6.2.1. SUBSCRIBE Request		6.2.1. SUBSCRIBE Request
	A SUBSCRIBE request message begins with the standard DNS Session		A SUBSCRIBE request message begins with the standard DNS Stateful
	Signaling 12-byte header [SessSig], followed by the SUBSCRIBE TLV. A		Operations 12-byte header [StatefulOp], followed by the SUBSCRIBE
	SUBSCRIBE request message is illustrated below:		TLV. A SUBSCRIBE request message is illustrated below:
	1 1 1 1 1 1		1 1 1 1 1 1
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
	+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
	| MESSAGE ID |		| MESSAGE ID |
	+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
	|QR| Opcode | Z | RCODE |		|QR| Opcode | Z | RCODE |
	+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
	| QDCOUNT (MUST BE ZERO) |		| QDCOUNT (MUST BE ZERO) |
	+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
	skipping to change at page 13, line 49 ¶		skipping to change at page 13, line 49 ¶
	Figure 1		Figure 1
	The MESSAGE ID field MUST be set to a unique value, that the client		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		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		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		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		response, or if the client has used it for a subscription which it
	has not yet cancelled using UNSUBSCRIBE. In the SUBSCRIBE response		has not yet cancelled using UNSUBSCRIBE. In the SUBSCRIBE response
	the server MUST echo back the MESSAGE ID value unchanged.		the server MUST echo back the MESSAGE ID value unchanged.
	The other header fields MUST be set as described in the DNS Session		The other header fields MUST be set as described in the DNS Stateful
	Signaling specification [SessSig]. The DNS Opcode is the Session		Operations specification [StatefulOp]. The DNS Opcode is the
	Signaling Opcode (tentatively 6). The four count fields MUST be		Stateful Operations Opcode (tentatively 6). The four count fields
	zero, and the corresponding four sections MUST be empty (i.e.,		MUST be zero, and the corresponding four sections MUST be empty
	absent).		(i.e., absent).
	The SSOP-TYPE is SUBSCRIBE (tentatively 0x40). The SSOP-LENGTH is		The SSOP-TYPE is SUBSCRIBE (tentatively 0x40). The SSOP-LENGTH is
	the length of the SSOP-DATA that follows, which specifies the name,		the length of the SSOP-DATA that follows, which specifies the name,
	type, and class of the record(s) being sought.		type, and class of the record(s) being sought.
	The SSOP-DATA for a SUBSCRIBE request MUST contain exactly one		The SSOP-DATA for a SUBSCRIBE request MUST contain exactly one
	question. The SSOP-DATA for a SUBSCRIBE request has no QDCOUNT field		question. The SSOP-DATA for a SUBSCRIBE request has no QDCOUNT field
	to specify more than one question. Since SUBSCRIBE requests are sent		to specify more than one question. Since SUBSCRIBE requests are sent
	over TCP, multiple SUBSCRIBE request messages can be concatenated in		over TCP, multiple SUBSCRIBE request messages can be concatenated in
	a single TCP stream and packed efficiently into TCP segments.		a single TCP stream and packed efficiently into TCP segments.
	skipping to change at page 16, line 10 ¶		skipping to change at page 16, line 10 ¶
	interpreted to mean "ALL", not "ANY". After accepting a subscription		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		where one or both of TYPE or CLASS are 255, the server MUST send Push
	Notification Updates for ALL record changes that match the		Notification Updates for ALL record changes that match the
	subscription, not just some of them.		subscription, not just some of them.
	6.2.2. SUBSCRIBE Response		6.2.2. SUBSCRIBE Response
	Each SUBSCRIBE request generates exactly one SUBSCRIBE response from		Each SUBSCRIBE request generates exactly one SUBSCRIBE response from
	the server.		the server.
	A SUBSCRIBE response message begins with the standard DNS Session		A SUBSCRIBE response message begins with the standard DNS Stateful
	Signaling 12-byte header [SessSig], possibly followed by one or more		Operations 12-byte header [StatefulOp], possibly followed by one or
	optional Modifier TLVs, such as a Retry Delay Modifier TLV.		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		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		SUBSCRIBE request. This is how the client knows which request is
	being responded to.		being responded to.
	A SUBSCRIBE response message MUST NOT contain a Session Signaling		A SUBSCRIBE response message MUST NOT contain a Stateful Operations
	Operation TLV. The Session Signaling Operation TLV is NOT copied		Operation TLV. The Stateful Operations Operation TLV is NOT copied
	from the SUBSCRIBE request.		from the SUBSCRIBE request.
	In the SUBSCRIBE response the RCODE indicates whether or not the		In the SUBSCRIBE response the RCODE indicates whether or not the
	subscription was accepted. Supported RCODEs are as follows:		subscription was accepted. Supported RCODEs are as follows:
	+------------+-------+----------------------------------------------+		+------------+-------+----------------------------------------------+
	| Mnemonic | Value | Description |		| Mnemonic | Value | Description |
	+------------+-------+----------------------------------------------+		+------------+-------+----------------------------------------------+
	| NOERROR | 0 | SUBSCRIBE successful. |		| NOERROR | 0 | SUBSCRIBE successful. |
	| FORMERR | 1 | Server failed to process request due to a |		| FORMERR | 1 | Server failed to process request due to a |
	| | | malformed request. |		| | | malformed request. |
	| SERVFAIL | 2 | Server failed to process request due to a |		| SERVFAIL | 2 | Server failed to process request due to a |
	| | | problem with the server. |		| | | problem with the server. |
	| NXDOMAIN | 3 | NOT APPLICABLE. DNS Push Notification |		| NXDOMAIN | 3 | NOT APPLICABLE. DNS Push Notification |
	| | | servers MUST NOT return NXDOMAIN errors in |		| | | servers MUST NOT return NXDOMAIN errors in |
	| | | response to SUBSCRIBE requests. |		| | | response to SUBSCRIBE requests. |
	| NOTIMP | 4 | Server does not recognize DNS Session |		| NOTIMP | 4 | Server does not recognize DNS Stateful |
	| | | Signaling Opcode. |		| | | Operations Opcode. |
	| REFUSED | 5 | Server refuses to process request for policy |		| REFUSED | 5 | Server refuses to process request for policy |
	| | | or security reasons. |		| | | or security reasons. |
	| NOTAUTH | 9 | Server is not authoritative for the |		| NOTAUTH | 9 | Server is not authoritative for the |
	| | | requested name. |		| | | requested name. |
	| SSOPNOTIMP | 11 | SUBSCRIBE operation not supported. |		| SSOPNOTIMP | 11 | SUBSCRIBE operation not supported. |
	+------------+-------+----------------------------------------------+		+------------+-------+----------------------------------------------+
	SUBSCRIBE Response codes		SUBSCRIBE Response codes
	This document specifies only these RCODE values for SUBSCRIBE		This document specifies only these RCODE values for SUBSCRIBE
	skipping to change at page 17, line 13 ¶		skipping to change at page 17, line 13 ¶
	value.		value.
	If the server sends a nonzero RCODE in the SUBSCRIBE response, either		If the server sends a nonzero RCODE in the SUBSCRIBE response, either
	the client is (at least partially) misconfigured, the server		the client is (at least partially) misconfigured, the server
	resources are exhausted, or there is some other unknown failure on		resources are exhausted, or there is some other unknown failure on
	the server. In any case, the client shouldn't retry the subscription		the server. In any case, the client shouldn't retry the subscription
	right away. Either end can terminate the connection, but the client		right away. Either end can terminate the connection, but the client
	may want to try this subscription again, or it may have other		may want to try this subscription again, or it may have other
	successful subscriptions that it doesn't want to abandon. If the		successful subscriptions that it doesn't want to abandon. If the
	server sends a nonzero RCODE then it SHOULD append a Retry Delay		server sends a nonzero RCODE then it SHOULD append a Retry Delay
	Modifier TLV [SessSig] to the response specifying a delay before the		Modifier TLV [StatefulOp] to the response specifying a delay before
	client attempts this operation again. Recommended values for the		the client attempts this operation again. Recommended values for the
	delay for different RCODE values are given below:		delay for different RCODE values are given below:
	For RCODE = 1 (FORMERR) the delay may be any value selected by the		For RCODE = 1 (FORMERR) the delay may be any value selected by the
	implementer. A value of five minutes is RECOMMENDED, to reduce		implementer. A value of five minutes is RECOMMENDED, to reduce
	the risk of high load from defective clients.		the risk of high load from defective clients.
	For RCODE = 2 (SERVFAIL) the delay should be chosen according to		For RCODE = 2 (SERVFAIL) the delay should be chosen according to
	the level of server overload and the anticipated duration of that		the level of server overload and the anticipated duration of that
	overload. By default, a value of one minute is RECOMMENDED. If a		overload. By default, a value of one minute is RECOMMENDED. If a
	more serious server failure occurs, the delay may be longer in		more serious server failure occurs, the delay may be longer in
	accordance with the specific problem encountered.		accordance with the specific problem encountered.
	For RCODE = 4 (NOTIMP), which occurs on a server that doesn't		For RCODE = 4 (NOTIMP), which occurs on a server that doesn't
	implement DNS Session Signaling [SessSig], it is unlikely that the		implement DNS Stateful Operations [StatefulOp], it is unlikely
	server will begin supporting DNS Session Signaling in the next few		that the server will begin supporting DNS Stateful Operations in
	minutes, so the retry delay SHOULD be one hour.		the next few minutes, so the retry delay SHOULD be one hour.
	For RCODE = 5 (REFUSED), which occurs on a server that implements		For RCODE = 5 (REFUSED), which occurs on a server that implements
	DNS Push Notifications, but is currently configured to disallow		DNS Push Notifications, but is currently configured to disallow
	DNS Push Notifications, the retry delay may be any value selected		DNS Push Notifications, the retry delay may be any value selected
	by the implementer and/or configured by the operator.		by the implementer and/or configured by the operator.
	This is a misconfiguration, since this server is listed in a		This is a misconfiguration, since this server is listed in a
	"_dns-push-tls._tcp.<zone>" SRV record, but the server itself is		"_dns-push-tls._tcp.<zone>" SRV record, but the server itself is
	not currently configured to support DNS Push Notifications. Since		not currently configured to support DNS Push Notifications. Since
	it is possible that the misconfiguration may be repaired at any		it is possible that the misconfiguration may be repaired at any
	time, the retry delay should not be set too high. By default, a		time, the retry delay should not be set too high. By default, a
	skipping to change at page 18, line 24 ¶		skipping to change at page 18, line 24 ¶
	For RCODE = 9 (NOTAUTH), the time delay applies to requests for other		For RCODE = 9 (NOTAUTH), the time delay applies to requests for other
	names falling within the same zone. Requests for names falling		names falling within the same zone. Requests for names falling
	within other zones are not subject to the delay. For all other		within other zones are not subject to the delay. For all other
	RCODEs the time delay applies to all subsequent requests to this		RCODEs the time delay applies to all subsequent requests to this
	server.		server.
	After sending an error response the server MAY allow the connection		After sending an error response the server MAY allow the connection
	to remain open, or MAY send a DNS Push Notification Retry Delay		to remain open, or MAY send a DNS Push Notification Retry Delay
	Operation TLV instructing the client to close the TCP connection, as		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.		Clients MUST correctly handle both cases.
	6.3. DNS Push Notification Updates		6.3. DNS Push Notification Updates
	Once a subscription has been successfully established, the server		Once a subscription has been successfully established, the server
	generates PUSH messages to send to the client as appropriate. In the		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		case that the answer set was non-empty at the moment the subscription
	was established, an initial PUSH message will be sent immediately		was established, an initial PUSH message will be sent immediately
	following the SUBSCRIBE Response. Subsequent changes to the answer		following the SUBSCRIBE Response. Subsequent changes to the answer
	set are then communicated to the client in subsequent PUSH messages.		set are then communicated to the client in subsequent PUSH messages.
	6.3.1. PUSH Message		6.3.1. PUSH Message
	A PUSH message begins with the standard DNS Session Signaling 12-byte		A PUSH message begins with the standard DNS Stateful Operations
	header [SessSig], followed by the PUSH TLV. A PUSH message is		12-byte header [StatefulOp], followed by the PUSH TLV. A PUSH
	illustrated below:		message is illustrated below:
	1 1 1 1 1 1		1 1 1 1 1 1
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
	+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
	| MESSAGE ID |		| MESSAGE ID |
	+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
	|QR| Opcode | Z | RCODE |		|QR| Opcode | Z | RCODE |
	+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
	| QDCOUNT (MUST BE ZERO) |		| QDCOUNT (MUST BE ZERO) |
	+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
	skipping to change at page 21, line 13 ¶		skipping to change at page 21, line 13 ¶
	Figure 2		Figure 2
	The MESSAGE ID field MUST be set to a unique value, that the server		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		is not currently using for any other active outgoing request that it
	has sent on this connection. The MESSAGE ID in the outgoing PUSH		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 is selected by the server and has no relationship to the
	MESSAGE ID in any of the client subscriptions it may relate to. In		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		the PUSH response the client MUST echo back the MESSAGE ID value
	unchanged.		unchanged.
	The other header fields MUST be set as described in the DNS Session		The other header fields MUST be set as described in the DNS Stateful
	Signaling specification [SessSig]. The DNS Opcode is the Session		Operations specification [StatefulOp]. The DNS Opcode is the
	Signaling Opcode (tentatively 6). The four count fields MUST be		Stateful Operations Opcode (tentatively 6). The four count fields
	zero, and the corresponding four sections MUST be empty (i.e.,		MUST be zero, and the corresponding four sections MUST be empty
	absent).		(i.e., absent).
	The SSOP-TYPE is PUSH (tentatively 0x41). The SSOP-LENGTH is the		The SSOP-TYPE is PUSH (tentatively 0x41). The SSOP-LENGTH is the
	length of the SSOP-DATA that follows, which specifies the changes		length of the SSOP-DATA that follows, which specifies the changes
	being communicated.		being communicated.
	The SSOP-DATA contains one or more Update records. A PUSH Message		The SSOP-DATA contains one or more Update records. A PUSH Message
	MUST contain at least one Update record. If a PUSH Message is		MUST contain at least one Update record. If a PUSH Message is
	received that contains no Update records, this is a fatal error, and		received that contains no Update records, this is a fatal error, and
	the receiver MUST immediately terminate the connection with a TCP RST		the receiver MUST immediately terminate the connection with a TCP RST
	(or equivalent for other protocols). The Update records are		(or equivalent for other protocols). The Update records are
	formatted in the customary way for Resource Records in DNS messages		formatted in the customary way for Resource Records in DNS messages
	with the stipulation that DNS name compression is not permitted in		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]		interpreted according to the same rules as for DNS Update [RFC2136]
	messages, namely:		messages, namely:
	Delete all RRsets from a name:		Delete all RRsets from a name:
	TTL=0, CLASS=ANY, RDLENGTH=0, TYPE=ANY.		TTL=0, CLASS=ANY, RDLENGTH=0, TYPE=ANY.
	Delete an RRset from a name:		Delete an RRset from a name:
	TTL=0, CLASS=ANY, RDLENGTH=0;		TTL=0, CLASS=ANY, RDLENGTH=0;
	TYPE specifies the RRset being deleted.		TYPE specifies the RRset being deleted.
	skipping to change at page 23, line 10 ¶		skipping to change at page 23, line 10 ¶
	that the record is still there. Once a subscription is cancelled		that the record is still there. Once a subscription is cancelled
	(individually, or as a result of the TCP connection being closed)		(individually, or as a result of the TCP connection being closed)
	record aging resumes and records are removed from the local cache		record aging resumes and records are removed from the local cache
	when their TTL reaches zero.		when their TTL reaches zero.
	6.3.2. PUSH Response		6.3.2. PUSH Response
	Each PUSH message generates exactly one PUSH response from the		Each PUSH message generates exactly one PUSH response from the
	receiver.		receiver.
	A PUSH response message begins with the standard DNS Session		A PUSH response message begins with the standard DNS Stateful
	Signaling 12-byte header [SessSig], possibly followed by one or more		Operations 12-byte header [StatefulOp], possibly followed by one or
	optional Modifier TLVs.		more optional Modifier TLVs.
	The MESSAGE ID field MUST echo the value given in the ID field of the		The MESSAGE ID field MUST echo the value given in the ID field of the
	PUSH message.		PUSH message.
	A PUSH response message MUST NOT contain a Session Signaling		A PUSH response message MUST NOT contain a Stateful Operations
	Operation TLV. The Session Signaling Operation TLV is NOT copied		Operation TLV. The Stateful Operations Operation TLV is NOT copied
	from the PUSH message.		from the PUSH message.
	In a PUSH response the RCODE MUST be zero. Receiving a PUSH response		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		with a nonzero RCODE is a fatal error, and the receiver MUST
	immediately terminate the connection with a TCP RST (or equivalent		immediately terminate the connection with a TCP RST (or equivalent
	for other protocols).		for other protocols).
	6.4. DNS Push Notification UNSUBSCRIBE		6.4. DNS Push Notification UNSUBSCRIBE
	To cancel an individual subscription without closing the entire		To cancel an individual subscription without closing the entire
	connection, the client sends an UNSUBSCRIBE message over the		connection, the client sends an UNSUBSCRIBE message over the
	established TCP connection to the server. The UNSUBSCRIBE message is		established TCP connection to the server. The UNSUBSCRIBE message is
	encoded in a DNS Session Signaling [SessSig] message. This		encoded in a DNS Stateful Operations [StatefulOp] message. This
	specification defines a DNS Session Signaling TLV for DNS Push		specification defines a DNS Stateful Operations TLV for DNS Push
	Notification UNSUBSCRIBE Requests/Responses (tentatively Session		Notification UNSUBSCRIBE Requests/Responses (tentatively Stateful
	Signaling Type Code 0x42).		Operations Type Code 0x42).
	A server MUST NOT initiate an UNSUBSCRIBE request. If a server does		A server MUST NOT initiate an UNSUBSCRIBE request. If a server does
	send a UNSUBSCRIBE request over the connection initiated by a client,		send a UNSUBSCRIBE request over the connection initiated by a client,
	it is an error and the client should acknowledge the request with the		it is an error and the client should acknowledge the request with the
	error response RCODE NOTAUTH (Not Authoritative).		error response RCODE NOTAUTH (Not Authoritative).
	6.4.1. UNSUBSCRIBE Request		6.4.1. UNSUBSCRIBE Request
	An UNSUBSCRIBE request message begins with the standard DNS Session		An UNSUBSCRIBE request message begins with the standard DNS Stateful
	Signaling 12-byte header [SessSig], followed by the UNSUBSCRIBE TLV.		Operations 12-byte header [StatefulOp], followed by the UNSUBSCRIBE
			TLV.
	1 1 1 1 1 1		1 1 1 1 1 1
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
	+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
	| MESSAGE ID |		| MESSAGE ID |
	+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
	|QR| Opcode | Z | RCODE |		|QR| Opcode | Z | RCODE |
	+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
	| QDCOUNT (MUST BE ZERO) |		| QDCOUNT (MUST BE ZERO) |
	+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
	skipping to change at page 27, line 10 ¶		skipping to change at page 27, line 10 ¶
	yet unacknowledged SUBSCRIBE request, and the SUBSCRIBE request is		yet unacknowledged SUBSCRIBE request, and the SUBSCRIBE request is
	subsequently unsuccessful for some reason, then when the UNSUBSCRIBE		subsequently unsuccessful for some reason, then when the UNSUBSCRIBE
	request is eventually processed it will be an UNSUBSCRIBE request for		request is eventually processed it will be an UNSUBSCRIBE request for
	a nonexistent subscription, which will result NXDOMAIN response.		a nonexistent subscription, which will result NXDOMAIN response.
	6.4.2. UNSUBSCRIBE Response		6.4.2. UNSUBSCRIBE Response
	Each UNSUBSCRIBE request generates exactly one UNSUBSCRIBE response		Each UNSUBSCRIBE request generates exactly one UNSUBSCRIBE response
	from the server.		from the server.
	An UNSUBSCRIBE response message begins with the standard DNS Session		An UNSUBSCRIBE response message begins with the standard DNS Stateful
	Signaling 12-byte header [SessSig], possibly followed by one or more		Operations 12-byte header [StatefulOp], possibly followed by one or
	optional Modifier TLVs, such as a Retry Delay Modifier TLV.		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		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		UNSUBSCRIBE request. This is how the client knows which request is
	being responded to.		being responded to.
	An UNSUBSCRIBE response message MUST NOT contain a Session Signaling		An UNSUBSCRIBE response message MUST NOT contain a Stateful
	Operation TLV. The Session Signaling Operation TLV is NOT copied		Operations Operation TLV. The Stateful Operations Operation TLV is
	from the UNSUBSCRIBE request.		NOT copied from the UNSUBSCRIBE request.
	In the UNSUBSCRIBE response the RCODE indicates whether or not the		In the UNSUBSCRIBE response the RCODE indicates whether or not the
	unsubscribe request was successful. Supported RCODEs are as follows:		unsubscribe request was successful. Supported RCODEs are as follows:
	+------------+-------+----------------------------------------------+		+------------+-------+----------------------------------------------+
	| Mnemonic | Value | Description |		| Mnemonic | Value | Description |
	+------------+-------+----------------------------------------------+		+------------+-------+----------------------------------------------+
	| NOERROR | 0 | UNSUBSCRIBE successful. |		| NOERROR | 0 | UNSUBSCRIBE successful. |
	| FORMERR | 1 | Server failed to process request due to a |		| FORMERR | 1 | Server failed to process request due to a |
	| | | malformed request. |		| | | malformed request. |
	| NXDOMAIN | 3 | Specified subscription does not exist. |		| NXDOMAIN | 3 | Specified subscription does not exist. |
	| NOTIMP | 4 | Server does not recognize DNS Session |		| NOTIMP | 4 | Server does not recognize DNS Stateful |
	| | | Signaling Opcode. |		| | | Operations Opcode. |
	| SSOPNOTIMP | 11 | UNSUBSCRIBE operation not supported. |		| SSOPNOTIMP | 11 | UNSUBSCRIBE operation not supported. |
	+------------+-------+----------------------------------------------+		+------------+-------+----------------------------------------------+
	UNSUBSCRIBE Response codes		UNSUBSCRIBE Response codes
	This document specifies only these RCODE values for UNSUBSCRIBE		This document specifies only these RCODE values for UNSUBSCRIBE
	Responses. Servers sending UNSUBSCRIBE Responses SHOULD use one of		Responses. Servers sending UNSUBSCRIBE Responses SHOULD use one of
	these values. However, future circumstances may create situations		these values. However, future circumstances may create situations
	where other RCODE values are appropriate in UNSUBSCRIBE Responses, so		where other RCODE values are appropriate in UNSUBSCRIBE Responses, so
	clients MUST be prepared to accept UNSUBSCRIBE Responses with any		clients MUST be prepared to accept UNSUBSCRIBE Responses with any
	skipping to change at page 28, line 14 ¶		skipping to change at page 28, line 14 ¶
	Nonzero RCODE values signal some kind of error.		Nonzero RCODE values signal some kind of error.
	RCODE value FORMERR indicates a message format error.		RCODE value FORMERR indicates a message format error.
	RCODE value NXDOMAIN indicates a MESSAGE ID that does not correspond		RCODE value NXDOMAIN indicates a MESSAGE ID that does not correspond
	to any active subscription.		to any active subscription.
	RCODE values NOTIMP and SSOPNOTIMP should not occur in practice.		RCODE values NOTIMP and SSOPNOTIMP should not occur in practice.
	A server would only generate NOTIMP if it did not support Session		A server would only generate NOTIMP if it did not support Stateful
	Signaling, and if the server does not support Session Signaling then		Operations, and if the server does not support Stateful Operations
	it should not be possible for a client to have an active subscription		then it should not be possible for a client to have an active
	to cancel.		subscription to cancel.
	Similarly, a server would only generate SSOPNOTIMP if it did not		Similarly, a server would only generate SSOPNOTIMP if it did not
	support Push Notifications, and if the server does not support Push		support Push Notifications, and if the server does not support Push
	Notifications then it should not be possible for a client to have an		Notifications then it should not be possible for a client to have an
	active subscription to cancel.		active subscription to cancel.
	Nonzero RCODE values other than NXDOMAIN indicate a serious problem		Nonzero RCODE values other than NXDOMAIN indicate a serious problem
	with the client. After sending an error response other than		with the client. After sending an error response other than
	NXDOMAIN, the server SHOULD send a DNS Session Signaling Retry Delay		NXDOMAIN, the server SHOULD send a DNS Stateful Operations Retry
	Operation TLV and then close the TCP connection, as described in the		Delay Operation TLV and then close the TCP connection, as described
	DNS Session Signaling specification [SessSig].		in the DNS Stateful Operations specification [StatefulOp].
	6.5. DNS Push Notification RECONFIRM		6.5. DNS Push Notification RECONFIRM
	Sometimes, particularly when used with a Discovery Proxy [DisProx], a		Sometimes, particularly when used with a Discovery Proxy [DisProx], a
	DNS Zone may contain stale data. When a client encounters data that		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		it believe may be stale (e.g., an SRV record referencing a target
	host+port that is not responding to connection requests) the client		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		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		data is still valid. For a Discovery Proxy, this causes it to issue
	new Multicast DNS requests to ascertain whether the target device is		new Multicast DNS requests to ascertain whether the target device is
	skipping to change at page 30, line 7 ¶		skipping to change at page 30, line 7 ¶
	If, after receiving a valid RECONFIRM request, the server determines		If, after receiving a valid RECONFIRM request, the server determines
	that the disputed records are in fact no longer valid, then		that the disputed records are in fact no longer valid, then
	subsequent DNS PUSH Messages will be generated to inform interested		subsequent DNS PUSH Messages will be generated to inform interested
	clients. Thus, one client discovering that a previously-advertised		clients. Thus, one client discovering that a previously-advertised
	device (like a network printer) is no longer present has the side		device (like a network printer) is no longer present has the side
	effect of informing all other interested clients that the device in		effect of informing all other interested clients that the device in
	question is now gone.		question is now gone.
	6.5.1. RECONFIRM Request		6.5.1. RECONFIRM Request
	A RECONFIRM request message begins with the standard DNS Session		A RECONFIRM request message begins with the standard DNS Stateful
	Signaling 12-byte header [SessSig], followed by the RECONFIRM TLV. A		Operations 12-byte header [StatefulOp], followed by the RECONFIRM
	RECONFIRM request message is illustrated below:		TLV. A RECONFIRM request message is illustrated below:
	1 1 1 1 1 1		1 1 1 1 1 1
	0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5		0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
	+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
	| MESSAGE ID |		| MESSAGE ID |
	+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
	|QR| Opcode | Z | RCODE |		|QR| Opcode | Z | RCODE |
	+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
	| QDCOUNT (MUST BE ZERO) |		| QDCOUNT (MUST BE ZERO) |
	+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+		+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
	skipping to change at page 30, line 51 ¶		skipping to change at page 30, line 51 ¶
	Figure 4		Figure 4
	The MESSAGE ID field MUST be set to a unique value, that the client		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		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		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		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		response, or if the client has used it for a subscription which it
	has not yet cancelled using UNSUBSCRIBE. In the RECONFIRM response		has not yet cancelled using UNSUBSCRIBE. In the RECONFIRM response
	the server MUST echo back the MESSAGE ID value unchanged.		the server MUST echo back the MESSAGE ID value unchanged.
	The other header fields MUST be set as described in the DNS Session		The other header fields MUST be set as described in the DNS Stateful
	Signaling specification [SessSig]. The DNS Opcode is the Session		Operations specification [StatefulOp]. The DNS Opcode is the
	Signaling Opcode (tentatively 6). The four count fields MUST be		Stateful Operations Opcode (tentatively 6). The four count fields
	zero, and the corresponding four sections MUST be empty (i.e.,		MUST be zero, and the corresponding four sections MUST be empty
	absent).		(i.e., absent).
	The SSOP-TYPE is RECONFIRM (tentatively 0x43). The SSOP-LENGTH is		The SSOP-TYPE is RECONFIRM (tentatively 0x43). The SSOP-LENGTH is
	the length of the data that follows, which specifies the name, type,		the length of the data that follows, which specifies the name, type,
	class, and content of the record being disputed.		class, and content of the record being disputed.
	The SSOP-DATA for a RECONFIRM request MUST contain exactly one		The SSOP-DATA for a RECONFIRM request MUST contain exactly one
	record. The SSOP-DATA for a RECONFIRM request has no count field to		record. The SSOP-DATA for a RECONFIRM request has no count field to
	specify more than one record. Since RECONFIRM requests are sent over		specify more than one record. Since RECONFIRM requests are sent over
	TCP, multiple RECONFIRM request messages can be concatenated in a		TCP, multiple RECONFIRM request messages can be concatenated in a
	single TCP stream and packed efficiently into TCP segments.		single TCP stream and packed efficiently into TCP segments.
	skipping to change at page 32, line 10 ¶		skipping to change at page 32, line 10 ¶
	the zone, and nothing else.		the zone, and nothing else.
	Aliasing is not supported. That is, a CNAME in a RECONFIRM message		Aliasing is not supported. That is, a CNAME in a RECONFIRM message
	matches only a literal CNAME record in the zone, and nothing else.		matches only a literal CNAME record in the zone, and nothing else.
	6.5.2. RECONFIRM Response		6.5.2. RECONFIRM Response
	Each RECONFIRM request generates exactly one RECONFIRM response from		Each RECONFIRM request generates exactly one RECONFIRM response from
	the server.		the server.
	A RECONFIRM response message begins with the standard DNS Session		A RECONFIRM response message begins with the standard DNS Stateful
	Signaling 12-byte header [SessSig], possibly followed by one or more		Operations 12-byte header [StatefulOp], possibly followed by one or
	optional Modifier TLVs, such as a Retry Delay Modifier TLV.		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		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		RECONFIRM request. This is how the client knows which request is
	being responded to.		being responded to.
	A RECONFIRM response message MUST NOT contain a Session Signaling		A RECONFIRM response message MUST NOT contain a Stateful Operations
	Operation TLV. The Session Signaling Operation TLV is NOT copied		Operation TLV. The Stateful Operations Operation TLV is NOT copied
	from the RECONFIRM request.		from the RECONFIRM request.
	In the RECONFIRM response the RCODE confirms receipt of the		In the RECONFIRM response the RCODE confirms receipt of the
	reconfirmation request. Supported RCODEs are as follows:		reconfirmation request. Supported RCODEs are as follows:
	+------------+-------+----------------------------------------------+		+------------+-------+----------------------------------------------+
	| Mnemonic | Value | Description |		| Mnemonic | Value | Description |
	+------------+-------+----------------------------------------------+		+------------+-------+----------------------------------------------+
	| NOERROR | 0 | RECONFIRM accepted. |		| NOERROR | 0 | RECONFIRM accepted. |
	| FORMERR | 1 | Server failed to process request due to a |		| FORMERR | 1 | Server failed to process request due to a |
	| | | malformed request. |		| | | malformed request. |
	| SERVFAIL | 2 | Server failed to process request due to a |		| SERVFAIL | 2 | Server failed to process request due to a |
	| | | problem with the server. |		| | | problem with the server. |
	| NXDOMAIN | 3 | NOT APPLICABLE. DNS Push Notification |		| NXDOMAIN | 3 | NOT APPLICABLE. DNS Push Notification |
	| | | servers MUST NOT return NXDOMAIN errors in |		| | | servers MUST NOT return NXDOMAIN errors in |
	| | | response to RECONFIRM requests. |		| | | response to RECONFIRM requests. |
	| NOTIMP | 4 | Server does not recognize DNS Session |		| NOTIMP | 4 | Server does not recognize DNS Stateful |
	| | | Signaling Opcode. |		| | | Operations Opcode. |
	| REFUSED | 5 | Server refuses to process request for policy |		| REFUSED | 5 | Server refuses to process request for policy |
	| | | or security reasons. |		| | | or security reasons. |
	| NOTAUTH | 9 | Server is not authoritative for the |		| NOTAUTH | 9 | Server is not authoritative for the |
	| | | requested name. |		| | | requested name. |
	| SSOPNOTIMP | 11 | RECONFIRM operation not supported. |		| SSOPNOTIMP | 11 | RECONFIRM operation not supported. |
	+------------+-------+----------------------------------------------+		+------------+-------+----------------------------------------------+
	RECONFIRM Response codes		RECONFIRM Response codes
	This document specifies only these RCODE values for RECONFIRM		This document specifies only these RCODE values for RECONFIRM
	skipping to change at page 33, line 14 ¶		skipping to change at page 33, line 14 ¶
	Nonzero RCODE values signal some kind of error.		Nonzero RCODE values signal some kind of error.
	RCODE value FORMERR indicates a message format error, for example		RCODE value FORMERR indicates a message format error, for example
	TYPE or CLASS being ANY (255).		TYPE or CLASS being ANY (255).
	RCODE value SERVFAIL indicates that the server has exhausted its		RCODE value SERVFAIL indicates that the server has exhausted its
	resources or other serious problem occurred.		resources or other serious problem occurred.
	RCODE values NOTIMP indicates that the server does not support		RCODE values NOTIMP indicates that the server does not support
	Session Signaling, and Session Signaling is required for RECONFIRM		Stateful Operations, and Stateful Operations is required for
	requests.		RECONFIRM requests.
	RCODE value REFUSED indicates that the server supports RECONFIRM		RCODE value REFUSED indicates that the server supports RECONFIRM
	requests but is currently not configured to accept them from this		requests but is currently not configured to accept them from this
	client.		client.
	RCODE value NOTAUTH indicates that the server is not authoritative		RCODE value NOTAUTH indicates that the server is not authoritative
	for the requested name, and can do nothing to remedy the apparent		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		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		to pass on the RECONFIRM request to the ultimate source of the
	information, and in these cases the server should return NOERROR.		information, and in these cases the server should return NOERROR.
	RCODE value SSOPNOTIMP indicates that the server does not support		RCODE value SSOPNOTIMP indicates that the server does not support
	RECONFIRM requests.		RECONFIRM requests.
	Nonzero RCODE values SERVFAIL, REFUSED and SSOPNOTIMP are benign from		Nonzero RCODE values SERVFAIL, REFUSED and SSOPNOTIMP are benign from
	the client's point of view. The client may log them to aid in		the client's point of view. The client may log them to aid in
	debugging, but otherwise they require no special action.		debugging, but otherwise they require no special action.
	Nonzero RCODE values other than these three indicate a serious		Nonzero RCODE values other than these three indicate a serious
	problem with the client. After sending an error response other than		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		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		6.6. Client-Initiated Termination
	An individual subscription is terminated by sending an UNSUBSCRIBE		An individual subscription is terminated by sending an UNSUBSCRIBE
	TLV for that specific subscription, or all subscriptions can be		TLV for that specific subscription, or all subscriptions can be
	cancelled at once by the client closing the connection. When a		cancelled at once by the client closing the connection. When a
	client terminates an individual subscription (via UNSUBSCRIBE) or all		client terminates an individual subscription (via UNSUBSCRIBE) or all
	subscriptions on that connection (by closing the connection) it is		subscriptions on that connection (by closing the connection) it is
	signaling to the server that it is longer interested in receiving		signaling to the server that it is longer interested in receiving
	those particular updates. It is informing the server that the server		those particular updates. It is informing the server that the server
	may release any state information it has been keeping with regards to		may release any state information it has been keeping with regards to
	these particular subscriptions.		these particular subscriptions.
	After terminating its last subscription on a connection via		After terminating its last subscription on a connection via
	UNSUBSCRIBE, a client MAY close the connection immediately, or it may		UNSUBSCRIBE, a client MAY close the connection immediately, or it may
	keep it open if it anticipates performing further operations on that		keep it open if it anticipates performing further operations on that
	connection in the future. If a client wishes to keep an idle		connection in the future. If a client wishes to keep an idle
	connection open, it MUST respect the maximum idle time required by		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		If a client plans to terminate one or more subscriptions on a
	connection and doesn't intend to keep that connection open, then as		connection and doesn't intend to keep that connection open, then as
	an efficiency optimization it MAY instead choose to simply close the		an efficiency optimization it MAY instead choose to simply close the
	connection, which implicitly terminates all subscriptions on that		connection, which implicitly terminates all subscriptions on that
	connection. This may occur because the client computer is being shut		connection. This may occur because the client computer is being shut
	down, is going to sleep, the application requiring the subscriptions		down, is going to sleep, the application requiring the subscriptions
	has terminated, or simply because the last active subscription on		has terminated, or simply because the last active subscription on
	that connection has been cancelled.		that connection has been cancelled.
	skipping to change at page 36, line 49 ¶		skipping to change at page 36, line 49 ¶
	up more quickly, but the client will still have to recreate any		up more quickly, but the client will still have to recreate any
	desired subscriptions.		desired subscriptions.
	8. IANA Considerations		8. IANA Considerations
	This document defines the service name: "_dns-push-tls._tcp".		This document defines the service name: "_dns-push-tls._tcp".
	It is only applicable for the TCP protocol.		It is only applicable for the TCP protocol.
	This name is to be published in the IANA Service Name Registry		This name is to be published in the IANA Service Name Registry
	[RFC6335][SN].		[RFC6335][SN].
	This document defines four DNS Session Signaling TLV types: SUBSCRIBE		This document defines four DNS Stateful Operations TLV types:
	with (tentative) value 0x40 (64), PUSH with (tentative) value 0x41		SUBSCRIBE with (tentative) value 0x40 (64), PUSH with (tentative)
	(65), UNSUBSCRIBE with (tentative) value 0x42 (66), and RECONFIRM		value 0x41 (65), UNSUBSCRIBE with (tentative) value 0x42 (66), and
	with (tentative) value 0x43 (67).		RECONFIRM with (tentative) value 0x43 (67).
	9. Acknowledgements		9. Acknowledgements
	The authors would like to thank Kiren Sekar and Marc Krochmal for		The authors would like to thank Kiren Sekar and Marc Krochmal for
	previous work completed in this field.		previous work completed in this field.
	This draft has been improved due to comments from Ran Atkinson, Tim		This draft has been improved due to comments from Ran Atkinson, Tim
	Chown, Mark Delany, Ralph Droms, Bernie Volz, Jan Komissar, Manju		Chown, Mark Delany, Ralph Droms, Bernie Volz, Jan Komissar, Manju
	Shankar Rao, Markus Stenberg, Dave Thaler, Soraia Zlatkovic, Sara		Shankar Rao, Markus Stenberg, Dave Thaler, Soraia Zlatkovic, Sara
	Dickinson, and Andrew Sullivan.		Dickinson, and Andrew Sullivan.
	10. References		10. References
	10.1. Normative References		10.1. Normative References
	[I-D.ietf-tls-tls13]		[I-D.ietf-tls-tls13]
	Rescorla, E., "The Transport Layer Security (TLS) Protocol		Rescorla, E., "The Transport Layer Security (TLS) Protocol
	Version 1.3", draft-ietf-tls-tls13-20 (work in progress),		Version 1.3", draft-ietf-tls-tls13-21 (work in progress),
	April 2017.		July 2017.
	[RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,		[RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
	DOI 10.17487/RFC0768, August 1980,		DOI 10.17487/RFC0768, August 1980, <https://www.rfc-
	<http://www.rfc-editor.org/info/rfc768>.		editor.org/info/rfc768>.
	[RFC0793] Postel, J., "Transmission Control Protocol", STD 7,		[RFC0793] Postel, J., "Transmission Control Protocol", STD 7,
	RFC 793, DOI 10.17487/RFC0793, September 1981,		RFC 793, DOI 10.17487/RFC0793, September 1981,
	<http://www.rfc-editor.org/info/rfc793>.		<https://www.rfc-editor.org/info/rfc793>.
	[RFC1034] Mockapetris, P., "Domain names - concepts and facilities",		[RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
	STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,		STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
	<http://www.rfc-editor.org/info/rfc1034>.		<https://www.rfc-editor.org/info/rfc1034>.
	[RFC1035] Mockapetris, P., "Domain names - implementation and		[RFC1035] Mockapetris, P., "Domain names - implementation and
	specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,		specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
	November 1987, <http://www.rfc-editor.org/info/rfc1035>.		November 1987, <https://www.rfc-editor.org/info/rfc1035>.
	[RFC1123] Braden, R., Ed., "Requirements for Internet Hosts -		[RFC1123] Braden, R., Ed., "Requirements for Internet Hosts -
	Application and Support", STD 3, RFC 1123,		Application and Support", STD 3, RFC 1123,
	DOI 10.17487/RFC1123, October 1989,		DOI 10.17487/RFC1123, October 1989, <https://www.rfc-
	<http://www.rfc-editor.org/info/rfc1123>.		editor.org/info/rfc1123>.
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119,		Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997, <https://www.rfc-
	<http://www.rfc-editor.org/info/rfc2119>.		editor.org/info/rfc2119>.
	[RFC2136] Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound,		[RFC2136] Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound,
	"Dynamic Updates in the Domain Name System (DNS UPDATE)",		"Dynamic Updates in the Domain Name System (DNS UPDATE)",
	RFC 2136, DOI 10.17487/RFC2136, April 1997,		RFC 2136, DOI 10.17487/RFC2136, April 1997,
	<http://www.rfc-editor.org/info/rfc2136>.		<https://www.rfc-editor.org/info/rfc2136>.
	[RFC2782] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for		[RFC2782] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for
	specifying the location of services (DNS SRV)", RFC 2782,		specifying the location of services (DNS SRV)", RFC 2782,
	DOI 10.17487/RFC2782, February 2000,		DOI 10.17487/RFC2782, February 2000, <https://www.rfc-
	<http://www.rfc-editor.org/info/rfc2782>.		editor.org/info/rfc2782>.
	[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security		[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
	(TLS) Protocol Version 1.2", RFC 5246,		(TLS) Protocol Version 1.2", RFC 5246,
	DOI 10.17487/RFC5246, August 2008,		DOI 10.17487/RFC5246, August 2008, <https://www.rfc-
	<http://www.rfc-editor.org/info/rfc5246>.		editor.org/info/rfc5246>.
	[RFC6066] Eastlake 3rd, D., "Transport Layer Security (TLS)		[RFC6066] Eastlake 3rd, D., "Transport Layer Security (TLS)
	Extensions: Extension Definitions", RFC 6066,		Extensions: Extension Definitions", RFC 6066,
	DOI 10.17487/RFC6066, January 2011,		DOI 10.17487/RFC6066, January 2011, <https://www.rfc-
	<http://www.rfc-editor.org/info/rfc6066>.		editor.org/info/rfc6066>.
	[RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S.		[RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S.
	Cheshire, "Internet Assigned Numbers Authority (IANA)		Cheshire, "Internet Assigned Numbers Authority (IANA)
	Procedures for the Management of the Service Name and		Procedures for the Management of the Service Name and
	Transport Protocol Port Number Registry", BCP 165,		Transport Protocol Port Number Registry", BCP 165,
	RFC 6335, DOI 10.17487/RFC6335, August 2011,		RFC 6335, DOI 10.17487/RFC6335, August 2011,
	<http://www.rfc-editor.org/info/rfc6335>.		<https://www.rfc-editor.org/info/rfc6335>.
	[RFC6895] Eastlake 3rd, D., "Domain Name System (DNS) IANA		[RFC6895] Eastlake 3rd, D., "Domain Name System (DNS) IANA
	Considerations", BCP 42, RFC 6895, DOI 10.17487/RFC6895,		Considerations", BCP 42, RFC 6895, DOI 10.17487/RFC6895,
	April 2013, <http://www.rfc-editor.org/info/rfc6895>.		April 2013, <https://www.rfc-editor.org/info/rfc6895>.
	[RFC7673] Finch, T., Miller, M., and P. Saint-Andre, "Using DNS-		[RFC7673] Finch, T., Miller, M., and P. Saint-Andre, "Using DNS-
	Based Authentication of Named Entities (DANE) TLSA Records		Based Authentication of Named Entities (DANE) TLSA Records
	with SRV Records", RFC 7673, DOI 10.17487/RFC7673, October		with SRV Records", RFC 7673, DOI 10.17487/RFC7673, October
	2015, <http://www.rfc-editor.org/info/rfc7673>.		2015, <https://www.rfc-editor.org/info/rfc7673>.
	[RFC7766] Dickinson, J., Dickinson, S., Bellis, R., Mankin, A., and		[RFC7766] Dickinson, J., Dickinson, S., Bellis, R., Mankin, A., and
	D. Wessels, "DNS Transport over TCP - Implementation		D. Wessels, "DNS Transport over TCP - Implementation
	Requirements", RFC 7766, DOI 10.17487/RFC7766, March 2016,		Requirements", RFC 7766, DOI 10.17487/RFC7766, March 2016,
	<http://www.rfc-editor.org/info/rfc7766>.		<https://www.rfc-editor.org/info/rfc7766>.
	[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		[SN] "Service Name and Transport Protocol Port Number
	Registry", <http://www.iana.org/assignments/		Registry", <http://www.iana.org/assignments/
	service-names-port-numbers/>.		service-names-port-numbers/>.
			[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		10.2. Informative References
	[DisProx] Cheshire, S., "Hybrid Unicast/Multicast DNS-Based Service		[DisProx] Cheshire, S., "Hybrid Unicast/Multicast DNS-Based Service
	Discovery", draft-ietf-dnssd-hybrid-06 (work in progress),		Discovery", draft-ietf-dnssd-hybrid-07 (work in progress),
	March 2017.		September 2017.
	[I-D.dukkipati-tcpm-tcp-loss-probe]		[I-D.dukkipati-tcpm-tcp-loss-probe]
	Dukkipati, N., Cardwell, N., Cheng, Y., and M. Mathis,		Dukkipati, N., Cardwell, N., Cheng, Y., and M. Mathis,
	"Tail Loss Probe (TLP): An Algorithm for Fast Recovery of		"Tail Loss Probe (TLP): An Algorithm for Fast Recovery of
	Tail Losses", draft-dukkipati-tcpm-tcp-loss-probe-01 (work		Tail Losses", draft-dukkipati-tcpm-tcp-loss-probe-01 (work
	in progress), February 2013.		in progress), February 2013.
	[I-D.ietf-dprive-dtls-and-tls-profiles]		[I-D.ietf-dprive-dtls-and-tls-profiles]
	Dickinson, S., Gillmor, D., and T. Reddy, "Usage and		Dickinson, S., Gillmor, D., and T. Reddy, "Usage and
	(D)TLS Profiles for DNS-over-(D)TLS", draft-ietf-dprive-		(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]		[I-D.sekar-dns-llq]
	Sekar, K., "DNS Long-Lived Queries", draft-sekar-dns-		Sekar, K., "DNS Long-Lived Queries", draft-sekar-dns-
	llq-01 (work in progress), August 2006.		llq-01 (work in progress), August 2006.
	[IPJ.9-4-TCPSYN]		[IPJ.9-4-TCPSYN]
	Eddy, W., "Defenses Against TCP SYN Flooding Attacks", The		Eddy, W., "Defenses Against TCP SYN Flooding Attacks", The
	Internet Protocol Journal, Cisco Systems, Volume 9,		Internet Protocol Journal, Cisco Systems, Volume 9,
	Number 4, December 2006.		Number 4, December 2006.
	[obs] "Observer Pattern", <https://en.wikipedia.org/wiki/		[obs] "Observer Pattern", <https://en.wikipedia.org/wiki/
	Observer_pattern>.		Observer_pattern>.
	[RFC2308] Andrews, M., "Negative Caching of DNS Queries (DNS		[RFC2308] Andrews, M., "Negative Caching of DNS Queries (DNS
	NCACHE)", RFC 2308, DOI 10.17487/RFC2308, March 1998,		NCACHE)", RFC 2308, DOI 10.17487/RFC2308, March 1998,
	<http://www.rfc-editor.org/info/rfc2308>.		<https://www.rfc-editor.org/info/rfc2308>.
	[RFC4287] Nottingham, M., Ed. and R. Sayre, Ed., "The Atom		[RFC4287] Nottingham, M., Ed. and R. Sayre, Ed., "The Atom
	Syndication Format", RFC 4287, DOI 10.17487/RFC4287,		Syndication Format", RFC 4287, DOI 10.17487/RFC4287,
	December 2005, <http://www.rfc-editor.org/info/rfc4287>.		December 2005, <https://www.rfc-editor.org/info/rfc4287>.
	[RFC4953] Touch, J., "Defending TCP Against Spoofing Attacks",		[RFC4953] Touch, J., "Defending TCP Against Spoofing Attacks",
	RFC 4953, DOI 10.17487/RFC4953, July 2007,		RFC 4953, DOI 10.17487/RFC4953, July 2007,
	<http://www.rfc-editor.org/info/rfc4953>.		<https://www.rfc-editor.org/info/rfc4953>.
	[RFC5077] Salowey, J., Zhou, H., Eronen, P., and H. Tschofenig,		[RFC5077] Salowey, J., Zhou, H., Eronen, P., and H. Tschofenig,
	"Transport Layer Security (TLS) Session Resumption without		"Transport Layer Security (TLS) Session Resumption without
	Server-Side State", RFC 5077, DOI 10.17487/RFC5077,		Server-Side State", RFC 5077, DOI 10.17487/RFC5077,
	January 2008, <http://www.rfc-editor.org/info/rfc5077>.		January 2008, <https://www.rfc-editor.org/info/rfc5077>.
	[RFC6281] Cheshire, S., Zhu, Z., Wakikawa, R., and L. Zhang,		[RFC6281] Cheshire, S., Zhu, Z., Wakikawa, R., and L. Zhang,
	"Understanding Apple's Back to My Mac (BTMM) Service",		"Understanding Apple's Back to My Mac (BTMM) Service",
	RFC 6281, DOI 10.17487/RFC6281, June 2011,		RFC 6281, DOI 10.17487/RFC6281, June 2011,
	<http://www.rfc-editor.org/info/rfc6281>.		<https://www.rfc-editor.org/info/rfc6281>.
	[RFC6762] Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762,		[RFC6762] Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762,
	DOI 10.17487/RFC6762, February 2013,		DOI 10.17487/RFC6762, February 2013, <https://www.rfc-
	<http://www.rfc-editor.org/info/rfc6762>.		editor.org/info/rfc6762>.
	[RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service		[RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service
	Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013,		Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013,
	<http://www.rfc-editor.org/info/rfc6763>.		<https://www.rfc-editor.org/info/rfc6763>.
	[RFC6824] Ford, A., Raiciu, C., Handley, M., and O. Bonaventure,		[RFC6824] Ford, A., Raiciu, C., Handley, M., and O. Bonaventure,
	"TCP Extensions for Multipath Operation with Multiple		"TCP Extensions for Multipath Operation with Multiple
	Addresses", RFC 6824, DOI 10.17487/RFC6824, January 2013,		Addresses", RFC 6824, DOI 10.17487/RFC6824, January 2013,
	<http://www.rfc-editor.org/info/rfc6824>.		<https://www.rfc-editor.org/info/rfc6824>.
	[RFC7413] Cheng, Y., Chu, J., Radhakrishnan, S., and A. Jain, "TCP		[RFC7413] Cheng, Y., Chu, J., Radhakrishnan, S., and A. Jain, "TCP
	Fast Open", RFC 7413, DOI 10.17487/RFC7413, December 2014,		Fast Open", RFC 7413, DOI 10.17487/RFC7413, December 2014,
	<http://www.rfc-editor.org/info/rfc7413>.		<https://www.rfc-editor.org/info/rfc7413>.
	[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,		[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,
	"Recommendations for Secure Use of Transport Layer		"Recommendations for Secure Use of Transport Layer
	Security (TLS) and Datagram Transport Layer Security		Security (TLS) and Datagram Transport Layer Security
	(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May		(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
	2015, <http://www.rfc-editor.org/info/rfc7525>.		2015, <https://www.rfc-editor.org/info/rfc7525>.
	[RFC7719] Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS		[RFC7719] Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS
	Terminology", RFC 7719, DOI 10.17487/RFC7719, December		Terminology", RFC 7719, DOI 10.17487/RFC7719, December
	2015, <http://www.rfc-editor.org/info/rfc7719>.		2015, <https://www.rfc-editor.org/info/rfc7719>.
	[RFC7858] Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D.,		[RFC7858] Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D.,
	and P. Hoffman, "Specification for DNS over Transport		and P. Hoffman, "Specification for DNS over Transport
	Layer Security (TLS)", RFC 7858, DOI 10.17487/RFC7858, May		Layer Security (TLS)", RFC 7858, DOI 10.17487/RFC7858, May
	2016, <http://www.rfc-editor.org/info/rfc7858>.		2016, <https://www.rfc-editor.org/info/rfc7858>.
	[XEP0060] Millard, P., Saint-Andre, P., and R. Meijer, "Publish-		[XEP0060] Millard, P., Saint-Andre, P., and R. Meijer, "Publish-
	Subscribe", XSF XEP 0060, July 2010.		Subscribe", XSF XEP 0060, July 2010.
	Authors' Addresses		Authors' Addresses
	Tom Pusateri		Tom Pusateri
	Seeking affiliation		Unaffiliated
	Hilton Head Island, SC		Raleigh, NC 27608
	USA		USA
	Phone: +1 843 473 7394		Phone: +1 919 867 1330
	Email: pusateri@bangj.com		Email: pusateri@bangj.com
	Stuart Cheshire		Stuart Cheshire
	Apple Inc.		Apple Inc.
	1 Infinite Loop		1 Infinite Loop
	Cupertino, CA 95014		Cupertino, CA 95014
	USA		USA
	Phone: +1 408 974 3207		Phone: +1 408 974 3207
	Email: cheshire@apple.com		Email: cheshire@apple.com
End of changes. 73 change blocks.
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