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
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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
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"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
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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
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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) |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
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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.
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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
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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
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