draft-ietf-dnssd-push-18.txt   draft-ietf-dnssd-push-19.txt 
Internet Engineering Task Force T. Pusateri Internet Engineering Task Force T. Pusateri
Internet-Draft Unaffiliated Internet-Draft Unaffiliated
Intended status: Standards Track S. Cheshire Intended status: Standards Track S. Cheshire
Expires: September 12, 2019 Apple Inc. Expires: September 25, 2019 Apple Inc.
March 11, 2019 March 24, 2019
DNS Push Notifications DNS Push Notifications
draft-ietf-dnssd-push-18 draft-ietf-dnssd-push-19
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 are relatively static. When efficiently for queries for data that are 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 https://datatracker.ietf.org/drafts/current/. Drafts is at https://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 September 12, 2019. This Internet-Draft will expire on September 25, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 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
(https://trustee.ietf.org/license-info) in effect on the date of (https://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 4, line 41 skipping to change at page 4, line 41
10.5 Leopard in 2007. Back to My Mac was designed in an era when the 10.5 Leopard in 2007. Back to My Mac was designed in an era when the
data center operations staff asserted that it was impossible for a data center operations staff asserted that it was impossible for a
server to handle large numbers of mostly-idle TCP connections, so LLQ server to handle large numbers of mostly-idle TCP connections, so LLQ
was defined as a UDP-based protocol, effectively replicating much of was defined as a UDP-based protocol, effectively replicating much of
TCP's connection state management logic in user space, and creating TCP's connection state management logic in user space, and creating
its own poor imitations of existing TCP features like the three-way its own poor imitations of existing TCP features like the three-way
handshake, flow control, and reliability. handshake, flow control, and reliability.
This document builds on experience gained with the LLQ protocol, with This document builds on experience gained with the LLQ protocol, with
an improved design. Instead of using UDP, this specification uses an improved design. Instead of using UDP, this specification uses
DNS Stateful Operations (DSO) [DSO] running over TLS over TCP, and DNS Stateful Operations (DSO) [RFC8490] running over TLS over TCP,
therefore doesn't need to reinvent existing TCP functionality. Using and therefore doesn't need to reinvent existing TCP functionality.
TCP also gives long-lived low-traffic connections better longevity Using TCP also gives long-lived low-traffic connections better
through NAT gateways without depending on the gateway to support NAT longevity through NAT gateways without depending on the gateway to
Port Mapping Protocol (NAT-PMP) [RFC6886] or Port Control Protocol support NAT Port Mapping Protocol (NAT-PMP) [RFC6886] or Port Control
(PCP) [RFC6887], or resorting to excessive keepalive traffic. Protocol (PCP) [RFC6887], or resorting to excessive keepalive
traffic.
3. Overview 3. Overview
A DNS Push Notification client subscribes for Push Notifications for A DNS Push Notification client subscribes for Push Notifications for
a particular RRSet by connecting to the appropriate Push Notification a particular RRSet by connecting to the appropriate Push Notification
server for that RRSet, and sending DSO message(s) indicating the server for that RRSet, and sending DSO message(s) indicating the
RRSet(s) of interest. When the client loses interest in receiving RRSet(s) of interest. When the client loses interest in receiving
further updates to these records, it unsubscribes. further updates to these records, it unsubscribes.
The DNS Push Notification server for a DNS zone is any server capable The DNS Push Notification server for a DNS zone is any server capable
skipping to change at page 6, line 27 skipping to change at page 6, line 27
(b) A DNS Push Notification client SHOULD NOT routinely keep a DNS (b) A DNS Push Notification client SHOULD NOT routinely keep a DNS
Push Notification subscription active 24 hours a day, 7 days a week, Push Notification subscription active 24 hours a day, 7 days a week,
just to keep a list in memory up to date so that if the user does just to keep a list in memory up to date so that if the user does
choose to bring up an on-screen display of that data, it can be choose to bring up an on-screen display of that data, it can be
displayed really fast. DNS Push Notifications are designed to be displayed really fast. DNS Push Notifications are designed to be
fast enough that there is no need to pre-load a "warm" list in memory fast enough that there is no need to pre-load a "warm" list in memory
just in case it might be needed later. just in case it might be needed later.
Generally, as described in the DNS Stateful Operations specification Generally, as described in the DNS Stateful Operations specification
[DSO], a client must not keep a session to a server open indefinitely [RFC8490], a client must not keep a session to a server open
if it has no subscriptions (or other operations) active on that indefinitely if it has no subscriptions (or other operations) active
session. A client MAY close a session as soon as it becomes idle, on that session. A client MAY close a session as soon as it becomes
and then if needed in the future, open a new session when required. idle, and then if needed in the future, open a new session when
Alternatively, a client MAY speculatively keep an idle session open required. Alternatively, a client MAY speculatively keep an idle
for some time, subject to the constraint that it MUST NOT keep a session open for some time, subject to the constraint that it MUST
session open that has been idle for more than the session's idle NOT keep a session open that has been idle for more than the
timeout (15 seconds by default) [DSO]. session's idle timeout (15 seconds by default) [RFC8490].
4. Transport 4. Transport
Other DNS operations like DNS Update [RFC2136] MAY use either User Other DNS operations like DNS Update [RFC2136] MAY use either User
Datagram Protocol (UDP) [RFC0768] or Transmission Control Protocol Datagram Protocol (UDP) [RFC0768] or Transmission Control Protocol
(TCP) [RFC0793] as the transport protocol, in keeping with the (TCP) [RFC0793] as the transport protocol, in keeping with the
historical precedent that DNS queries must first be sent over UDP historical precedent that DNS queries must first be sent over UDP
[RFC1123]. This requirement to use UDP has subsequently been relaxed [RFC1123]. This requirement to use UDP has subsequently been relaxed
[RFC7766]. [RFC7766].
In keeping with the more recent precedent, DNS Push Notification is In keeping with the more recent precedent, DNS Push Notification is
defined only for TCP. DNS Push Notification clients MUST use DNS defined only for TCP. DNS Push Notification clients MUST use DNS
Stateful Operations (DSO) [DSO] running over TLS over TCP [RFC7858]. Stateful Operations [RFC8490] running over TLS over TCP [RFC7858].
Connection setup over TCP ensures return reachability and alleviates Connection setup over TCP ensures return reachability and alleviates
concerns of state overload at the server through anonymous concerns of state overload at the server through anonymous
subscriptions. All subscribers are guaranteed to be reachable by the subscriptions. All subscribers are guaranteed to be reachable by the
server by virtue of the TCP three-way handshake. Flooding attacks server by virtue of the TCP three-way handshake. Flooding attacks
are possible with any protocol, and a benefit of TCP is that there are possible with any protocol, and a benefit of TCP is that there
are already established industry best practices to guard against SYN are already established industry best practices to guard against SYN
flooding and similar attacks [SYN] [RFC4953]. flooding and similar attacks [SYN] [RFC4953].
Use of TCP also allows DNS Push Notifications to take advantage of Use of TCP also allows DNS Push Notifications to take advantage of
skipping to change at page 9, line 8 skipping to change at page 9, line 8
employ various techniques to limit subscriptions to a manageable employ various techniques to limit subscriptions to a manageable
level. Correspondingly, the client is free to establish simultaneous level. Correspondingly, the client is free to establish simultaneous
sessions to alternate DNS servers that support DNS Push Notifications sessions to alternate DNS servers that support DNS Push Notifications
for the zone and distribute subscriptions at the client's discretion. for the zone and distribute subscriptions at the client's discretion.
In this way, both clients and servers can react to resource In this way, both clients and servers can react to resource
constraints. constraints.
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 Stateful Operations (DSO) [DSO]. and makes use of DNS Stateful Operations (DSO) [RFC8490].
For details of the DSO message format refer to the DNS Stateful For details of the DSO message format refer to the DNS Stateful Oper-
Operations specification [DSO]. Those details are not repeated here. ations specification [RFC8490]. Those details are not repeated here.
DNS Push Notification clients and servers MUST support DSO. A single DNS Push Notification clients and servers MUST support DSO. A single
server can support DNS Queries, DNS Updates, and DNS Push server can support DNS Queries, DNS Updates, and DNS Push
Notifications (using DSO) on the same TCP port. Notifications (using DSO) on the same TCP port.
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 DSO A typical DNS Push Notification client will immediately issue a DSO
skipping to change at page 10, line 36 skipping to change at page 10, line 36
In many contexts, the recursive resolver will be able to handle Push In many contexts, the recursive resolver will be able to handle Push
Notifications for all names that the client may need to follow. Use Notifications for all names that the client may need to follow. Use
of VPN tunnels and split-view DNS can create some additional of VPN tunnels and split-view DNS can create some additional
complexity in the client software here; the techniques to handle VPN complexity in the client software here; the techniques to handle VPN
tunnels and split-view DNS for DNS Push Notifications are the same as tunnels and split-view DNS for DNS Push Notifications are the same as
those already used to handle this for normal DNS queries. those already used to handle this for normal DNS queries.
If the recursive resolver does not support DNS over TLS, or does If the recursive resolver does not support DNS over TLS, or does
support DNS over TLS but is not listening on TCP port 853, or does support DNS over TLS but is not listening on TCP port 853, or does
support DNS over TLS on TCP port 853 but does not support DSO on that support DNS over TLS on TCP port 853 but does not support DSO on that
port, then the DSO Session session establishment will fail [DSO]. port, then the DSO Session session establishment will fail [RFC8490].
If the recursive resolver does support DSO but not Push Notification If the recursive resolver does support DSO but not Push Notification
subscriptions, then it will return the DSO error code, DSOTYPENI subscriptions, then it will return the DSO error code, DSOTYPENI
(11). (11).
In some cases, the recursive resolver may support DSO and Push In some cases, the recursive resolver may support DSO and Push
Notification subscriptions, but may not be able to subscribe for Push Notification subscriptions, but may not be able to subscribe for Push
Notifications for a particular name. In this case, the recursive Notifications for a particular name. In this case, the recursive
resolver should return an informative error code to the client so resolver should return an informative error code to the client so
that the client can make an informed decision how to handle the that the client can make an informed decision how to handle the
skipping to change at page 14, line 8 skipping to change at page 14, line 8
the client device MUST respect the DNS TTL values on records it the client device MUST respect the DNS TTL values on records it
receives, and store them in its local cache with this lifetime. This receives, and store them in its local cache with this lifetime. This
means that, as long as the DNS TTL values on the authoritative means that, as long as the DNS TTL values on the authoritative
records were set to reasonable values, repeated application of this records were set to reasonable values, repeated application of this
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
indicates its desire to receive DNS Push Notifications for a given then indicates its desire to receive DNS Push Notifications for
domain name by sending a SUBSCRIBE request to the server. A a given domain name by sending a SUBSCRIBE request to the server.
SUBSCRIBE request is encoded in a DSO message [DSO]. This A SUBSCRIBE request is encoded in a DSO message [RFC8490].
specification defines a primary DSO TLV for DNS Push Notification This specification defines a primary DSO TLV for DNS Push
SUBSCRIBE Requests (tentatively DSO Type Code 0x40). Notification SUBSCRIBE Requests (tentatively DSO 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 MUST NOT send a SUBSCRIBE request over an existing client. A server MUST NOT send a SUBSCRIBE request over an existing
session from a client. If a server does send a SUBSCRIBE request session from a client. If a server does send a SUBSCRIBE request
over a DSO session initiated by a client, this is a fatal error and over a DSO session initiated by a client, this is a fatal error and
the client should immediately abort the connection with a TCP RST (or the client should immediately abort the connection with a TCP RST (or
equivalent for other protocols). equivalent for other protocols).
6.2.1. SUBSCRIBE Request 6.2.1. SUBSCRIBE Request
A SUBSCRIBE request begins with the standard DSO 12-byte header A SUBSCRIBE request begins with the standard DSO 12-byte header
[DSO], followed by the SUBSCRIBE primary TLV. A SUBSCRIBE request [RFC8490], followed by the SUBSCRIBE primary TLV. A SUBSCRIBE
message is illustrated in Figure 1. request message is illustrated in 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 DSO session. For is not using for any other active operation on this DSO session. For
the purposes here, a MESSAGE ID is in use on this session if the the purposes here, a MESSAGE ID is in use on this session 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 DSO The other header fields MUST be set as described in the DSO spec-
specification [DSO]. The DNS OPCODE field contains the OPCODE value ification [RFC8490]. The DNS OPCODE field contains the OPCODE value
for DNS Stateful Operations (6). The four count fields MUST be zero, for DNS Stateful Operations (6). The four count fields MUST be zero,
and the corresponding four sections MUST be empty (i.e., absent). and the corresponding four sections MUST be empty (i.e., absent).
The DSO-TYPE is SUBSCRIBE (tentatively 0x40). The DSO-TYPE is SUBSCRIBE (tentatively 0x40).
The DSO-LENGTH is the length of the DSO-DATA that follows, which The DSO-LENGTH is the length of the DSO-DATA that follows, which
specifies the name, type, and class of the record(s) being sought. specifies the name, type, and class of the record(s) being sought.
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
skipping to change at page 17, line 11 skipping to change at page 17, line 11
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 begins with the standard DSO 12-byte header A SUBSCRIBE response begins with the standard DSO 12-byte header
[DSO], possibly followed by one or more optional TLVs, such as a [RFC8490], possibly followed by one or more optional TLVs, such as a
Retry Delay TLV. Retry Delay 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 include a SUBSCRIBE TLV. If a A SUBSCRIBE response message MUST NOT include a SUBSCRIBE TLV. If a
client receives a SUBSCRIBE response message containing a SUBSCRIBE client receives a SUBSCRIBE response message containing a SUBSCRIBE
TLV then the response message is processed but the SUBSCRIBE TLV MUST TLV then the response message is processed but the SUBSCRIBE TLV MUST
be silently ignored. be silently ignored.
skipping to change at page 18, line 23 skipping to change at page 18, line 23
server right away. If multiple SRV records were returned as server right away. If multiple SRV records were returned as
described in Section 6.1, Paragraph 7, a subsequent server can be described in Section 6.1, Paragraph 7, a subsequent server can be
tried immediately. tried immediately.
If the client has other successful subscriptions to this server, If the client has other successful subscriptions to this server,
these subscriptions remain even though additional subscriptions may these subscriptions remain even though additional subscriptions may
be refused. Neither the client nor the server are required to close be refused. Neither the client nor the server are required to close
the connection, although, either end may choose to do so. the connection, although, either end may choose to do so.
If the server sends a nonzero RCODE then it SHOULD append a Retry If the server sends a nonzero RCODE then it SHOULD append a Retry
Delay TLV [DSO] to the response specifying a delay before the client Delay TLV [RFC8490] to the response specifying a delay before the
attempts this operation again. Recommended values for the delay for client attempts this operation again. Recommended values for the
different RCODE values are given below. These recommended values delay for different RCODE values are given below. These recommended
apply both to the default values a server should place in the Retry values apply both to the default values a server should place in the
Delay TLV, and the default values a client should assume if the Retry Delay TLV, and the default values a client should assume if the
server provides no Retry Delay TLV. server provides no Retry Delay TLV.
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 Stateful Operations [DSO], it is unlikely that the implement DNS Stateful Operations [RFC8490], it is unlikely that
server will begin supporting DSO in the next few minutes, so the the server will begin supporting DSO in the next few minutes, so
retry delay SHOULD be one hour. Note that in such a case, a the retry delay SHOULD be one hour. Note that in such a case, a
server that doesn't implement DSO is unlikely to place a Retry server that doesn't implement DSO is unlikely to place a Retry
Delay TLV in its response, so this recommended value in particular Delay TLV in its response, so this recommended value in particular
applies to what a client should assume by default. applies to what a client should assume by default.
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.
If the server being queried is listed in a If the server being queried is listed in a
skipping to change at page 19, line 47 skipping to change at page 19, line 47
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 session to After sending an error response the server MAY allow the session to
remain open, or MAY send a DNS Push Notification Retry Delay remain open, or MAY send a DNS Push Notification Retry Delay
Operation TLV instructing the client to close the session, as Operation TLV instructing the client to close the session, as
described in the DSO specification [DSO]. Clients MUST correctly described in the DSO specification [RFC8490]. Clients MUST correctly
handle both cases. 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 already non-empty at the moment the case that the answer set was already non-empty at the moment the
subscription was established, an initial PUSH message will be sent subscription was established, an initial PUSH message will be sent
immediately following the SUBSCRIBE Response. Subsequent changes to immediately following the SUBSCRIBE Response. Subsequent changes to
the answer set are then communicated to the client in subsequent PUSH the answer set are then communicated to the client in subsequent PUSH
messages. messages.
6.3.1. PUSH Message 6.3.1. PUSH Message
A PUSH unidirectional message begins with the standard DSO 12-byte A PUSH unidirectional message begins with the standard DSO 12-byte
header [DSO], followed by the PUSH primary TLV. A PUSH message is header [RFC8490], followed by the PUSH primary TLV. A PUSH message
illustrated in Figure 2. is illustrated in Figure 2.
In accordance with the definition of DSO unidirectional messages, the In accordance with the definition of DSO unidirectional messages, the
MESSAGE ID field MUST be zero. There is no client response to a PUSH MESSAGE ID field MUST be zero. There is no client response to a PUSH
message. message.
The other header fields MUST be set as described in the DSO The other header fields MUST be set as described in the DSO spec-
specification [DSO]. The DNS OPCODE field contains the OPCODE value ification [RFC8490]. The DNS OPCODE field contains the OPCODE value
for DNS Stateful Operations (6). The four count fields MUST be zero, for DNS Stateful Operations (6). The four count fields MUST be zero,
and the corresponding four sections MUST be empty (i.e., absent). and the corresponding four sections MUST be empty (i.e., absent).
The DSO-TYPE is PUSH (tentatively 0x41). The DSO-TYPE is PUSH (tentatively 0x41).
The DSO-LENGTH is the length of the DSO-DATA that follows, which The DSO-LENGTH is the length of the DSO-DATA that follows, which
specifies the changes being communicated. specifies the changes being communicated.
The DSO-DATA contains one or more change notifications. A PUSH The DSO-DATA contains one or more change notifications. A PUSH
Message MUST contain at least one change notification. If a PUSH Message MUST contain at least one change notification. If a PUSH
Message is received that contains no change notifications, this is a Message is received that contains no change notifications, this is a
fatal error, and the receiver MUST immediately terminate the fatal error, and the receiver MUST immediately terminate the
connection with a TCP RST (or equivalent for other protocols). The connection with a TCP RST (or equivalent for other protocols).
change notifications are formatted similarly to how DNS Resource
Records are conventionally expressed in DNS messages, and are
interpreted as described below.
If the signed 32-bit TTL is in the range 0 to 604,800 seconds (one The change notification records are formatted similarly to how DNS
week), then a new DNS Resource Record with the given name, type, Resource Records are conventionally expressed in DNS messages, as
class and RDATA is added. The maximum record lifetime supported in a illustrated in Figure 2, and are interpreted as described below.
PUSH Message is one week. In the event that the DNS record in
question has an actual TTL greater than one week, the TTL is reported
in the PUSH Message as being one week. A TTL of 0 means that this
record should be retained for as long as the subscription is active,
and should be discarded immediately the moment the subscription is
cancelled.
If the signed 32-bit TTL has the value -1, then the DNS Resource The TTL field holds an unsigned 32-bit integer [RFC2181]. If the TTL
Record with the given name, type, class and RDATA is removed. is in the range 0 to 2,147,483,647 seconds (2^31 - 1, or 0x7FFFFFFF),
then a new DNS Resource Record with the given name, type, class and
RDATA is added. A TTL of 0 means that this record should be retained
for as long as the subscription is active, and should be discarded
immediately the moment the subscription is cancelled.
If the signed 32-bit TTL has the value -2, then this is a If the TTL has the value 0xFFFFFFFF, then the DNS Resource Record
'collective' remove notification. For collective remove with the given name, type, class and RDATA is removed.
notifications RDLEN MUST be zero and consequently the RDATA MUST be
empty. If a change notification is received where TTL = -2 and RDLEN If the TTL has the value 0xFFFFFFFE, then this is a 'collective'
is not zero, this is a fatal error, and the receiver MUST immediately remove notification. For collective remove notifications RDLEN MUST
be zero and consequently the RDATA MUST be empty. If a change
notification is received where TTL = 0xFFFFFFFE and RDLEN is not
zero, this is a fatal error, and the receiver MUST immediately
terminate the connection with a TCP RST (or equivalent for other terminate the connection with a TCP RST (or equivalent for other
protocols). There are three types of collective remove notification: protocols). There are three types of collective remove notification:
For collective remove notifications, if CLASS is ANY, then for the For collective remove notifications, if CLASS is 255 (ANY), then for
given name this deletes all records of all types in all classes. In the given name this deletes all records of all types in all classes.
this case TYPE MUST be set to ANY on tranmission, and MUST be In this case TYPE MUST be set to zero on transmission, and MUST be
silently ignored on reception. silently ignored on reception.
For collective remove notifications, if CLASS is not ANY and TYPE is For collective remove notifications, if CLASS is not 255 (ANY) and
is ANY then for the given name this deletes all records of all types TYPE is 255 (ANY) then for the given name this deletes all records of
in the specified class. all types in the specified class.
For collective remove notifications, if CLASS is not ANY and TYPE is For collective remove notifications, if CLASS is not 255 (ANY) and
is not ANY then for the given name this deletes all records of the TYPE is not 255 (ANY) then for the given name this deletes all
specified type in the specified class. records of the specified type in the specified class.
Summary of change notification types: Summary of change notification types:
Delete all RRsets from a name, in all classes Delete all RRsets from a name, in all classes
TTL=-2, RDLENGTH=0, TYPE=ANY, CLASS=ANY TTL=0xFFFFFFFE, RDLENGTH=0, CLASS=255 (ANY)
Delete all RRsets from a name, in given class: Delete all RRsets from a name, in given class:
TTL=-2, RDLENGTH=0, TYPE=ANY TTL=0xFFFFFFFE, RDLENGTH=0, CLASS specifies class, TYPE=255 (ANY)
CLASS specifies class (usually class "IN")
Delete specified RRset from a name, in given class: Delete specified RRset from a name, in given class:
TTL=-2, RDLENGTH=0 TTL=0xFFFFFFFE, RDLENGTH=0
CLASS and TYPE specify the RRset being deleted CLASS and TYPE specify the RRset being deleted
Delete an individual RR from a name: Delete an individual RR from a name:
TTL=-1 TTL=0xFFFFFFFF
CLASS, TYPE, RDLENGTH and RDATA specify the RR being deleted. CLASS, TYPE, RDLENGTH and RDATA specify the RR being deleted.
Add individual RR to a name Add individual RR to a name
TTL>=0 TTL>=0
CLASS, TYPE, RDLENGTH, RDATA and TTL specify the RR being added. CLASS, TYPE, RDLENGTH, RDATA and TTL specify the RR being added.
Note that it is valid for the RDATA of an added or removed DNS Note that it is valid for the RDATA of an added or removed DNS
Resource Record to be empty (zero length). For example, an Address Resource Record to be empty (zero length). For example, an Address
Prefix List Resource Record [RFC3123] may have empty RDATA. Prefix List Resource Record [RFC3123] may have empty RDATA.
Therefore, a change notification with RDLEN=0 does not automatically Therefore, a change notification with RDLEN=0 does not automatically
indicate a remove notification. If RDLEN=0 and TTL >= 0, this change indicate a remove notification. If RDLEN=0 and TTL is the in the
notification signals the addition of a record with the given name, range 0 - 0x7FFFFFFF, this change notification signals the addition
type, class, and empty RDATA. If RDLEN=0 and TTL = -1, this change of a record with the given name, type, class, and empty RDATA. If
notification signals the removal specifically of that single record RDLEN=0 and TTL = 0xFFFFFFFF, this change notification signals the
with the given name, type, class, and empty RDATA. removal specifically of that single record with the given name, type,
class, and empty RDATA.
If the TTL is any value other than 0xFFFFFFFF, 0xFFFFFFFE, or a value
in the range 0 - 0x7FFFFFFF, then the receiver SHOULD silently ignore
this particular change notification record. The connection is not
terminated and other valid change notification records within this
PUSH message are processed as usual.
For efficiency, when generating a PUSH message, a server SHOULD For efficiency, when generating a PUSH message, a server SHOULD
include as many change notifications as it has immediately available include as many change notifications as it has immediately available
to send, rather than sending each change notification as a separate to send, rather than sending each change notification as a separate
DSO message. Once it has exhausted the list of change notifications DSO message. Once it has exhausted the list of change notifications
immediately available to send, a server SHOULD then send the PUSH immediately available to send, a server SHOULD then send the PUSH
message immediately, rather than waiting to see if additional change message immediately, rather than waiting to see if additional change
notifications become available. notifications become available.
For efficiency, when generating a PUSH message, a server SHOULD use For efficiency, when generating a PUSH message, a server SHOULD use
standard DNS name compression, with offsets relative to the beginning standard DNS name compression, with offsets relative to the beginning
of the DNS message [RFC1035]. When multiple change notifications in of the DNS message [RFC1035]. When multiple change notifications in
a single PUSH message have the same owner name, this name compression a single PUSH message have the same owner name, this name compression
can yield significant savings. Name compression should be performed can yield significant savings. Name compression should be performed
as specified in Section 18.14 of the Multicast DNS specification as specified in Section 18.14 of the Multicast DNS specification
[RFC6762], namely, owner names should always be compressed, and names [RFC6762], namely, owner names should always be compressed, and names
appearing within only the RDATA of the following DNS types should be appearing within RDATA should be compressed for only the RR types
compressed: listed below:
NS, CNAME, PTR, DNAME, SOA, MX, AFSDB, RT, KX, RP, PX, SRV, NSEC NS, CNAME, PTR, DNAME, SOA, MX, AFSDB, RT, KX, RP, PX, SRV, NSEC
Servers MAY generate PUSH messages up to a DNS message length of Servers may generate PUSH messages up to a maximum DNS message length
16,382 bytes, counting from the start of the DSO 12-byte header. of 16,382 bytes, counting from the start of the DSO 12-byte header.
Including the two-byte length prefix that is used to frame DNS over a Including the two-byte length prefix that is used to frame DNS over a
byte stream like TLS, this makes a total of 16,384 bytes. Servers byte stream like TLS, this makes a total of 16,384 bytes. Servers
SHOULD NOT generate PUSH messages larger than this. Where the MUST NOT generate PUSH messages larger than this. Where the
immediately available change notifications are sufficient to exceed a immediately available change notifications are sufficient to exceed a
DNS message length of 16,382 bytes, the change notifications SHOULD DNS message length of 16,382 bytes, the change notifications MUST be
be communicated in separate PUSH messages of up to 16,382 bytes each. communicated in separate PUSH messages of up to 16,382 bytes each.
DNS name compression becomes less effective for messages larger than DNS name compression becomes less effective for messages larger than
16,384 bytes, so little efficiency benefit is gained by sending 16,384 bytes, so little efficiency benefit is gained by sending
messages larger than this. messages larger than this.
If a client receives a PUSH message with a DNS message length larger If a client receives a PUSH message with a DNS message length larger
than 16,382 bytes, the this is a fatal error, and the receiver MUST than 16,382 bytes, the this 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).
1 1 1 1 1 1 1 1 1 1 1 1
skipping to change at page 23, line 31 skipping to change at page 23, line 33
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| DSO-LENGTH (number of octets in DSO-DATA) | | DSO-LENGTH (number of octets in DSO-DATA) |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ \ +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ \
\ NAME \ \ \ NAME \ \
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| TYPE | | | TYPE | |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| CLASS | | | CLASS | |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| TTL | | | TTL | |
| (32-bit signed big-endian integer) | > DSO-DATA | (32-bit unsigned big-endian integer) | > DSO-DATA
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
| RDLEN | | | RDLEN | |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
\ RDATA (sized as necessary) \ | \ RDATA (sized as necessary) \ |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ |
: NAME, TYPE, CLASS, TTL, RDLEN, RDATA : | : NAME, TYPE, CLASS, TTL, RDLEN, RDATA : |
: Repeated As Necessary : / : Repeated As Necessary : /
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ / +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ /
Figure 2: PUSH Message Figure 2: PUSH Message
skipping to change at page 24, line 15 skipping to change at page 24, line 18
record addition/deletion is silently ignored. Processing of other record addition/deletion is silently ignored. Processing of other
additions and deletions in this message is not affected. The DSO additions and deletions in this message is not affected. The DSO
session is not closed. This is to allow for the unavoidable race session is not closed. This is to allow for the unavoidable race
condition where a client sends an outbound UNSUBSCRIBE while inbound condition where a client sends an outbound UNSUBSCRIBE while inbound
PUSH messages for that subscription from the server are still in PUSH messages for that subscription from the server are still in
flight. flight.
In the case where a single change affects more than one active In the case where a single change affects more than one active
subscription, only one PUSH message is sent. For example, a PUSH subscription, only one PUSH message is sent. For example, a PUSH
message adding a given record may match both a SUBSCRIBE request with message adding a given record may match both a SUBSCRIBE request with
the same TYPE and a different SUBSCRIBE request with TYPE=ANY. It is the same TYPE and a different SUBSCRIBE request with TYPE=ANY (255).
not the case that two PUSH messages are sent because the new record It is not the case that two PUSH messages are sent because the new
matches two active subscriptions. record matches two active subscriptions.
The server SHOULD encode change notifications in the most efficient The server SHOULD encode change notifications in the most efficient
manner possible. For example, when three AAAA records are deleted manner possible. For example, when three AAAA records are deleted
from a given name, and no other AAAA records exist for that name, the from a given name, and no other AAAA records exist for that name, the
server SHOULD send a "delete an RRset from a name" PUSH message, not server SHOULD send a "delete an RRset from a name" PUSH message, not
three separate "delete an individual RR from a name" PUSH messages. three separate "delete an individual RR from a name" PUSH messages.
Similarly, when both an SRV and a TXT record are deleted from a given Similarly, when both an SRV and a TXT record are deleted from a given
name, and no other records of any kind exist for that name, the name, and no other records of any kind exist for that name, the
server SHOULD send a "delete all RRsets from a name" PUSH message, server SHOULD send a "delete all RRsets from a name" PUSH message,
not two separate "delete an RRset from a name" PUSH messages. not two separate "delete an RRset from a name" PUSH messages.
skipping to change at page 25, line 10 skipping to change at page 25, line 10
record is still there. Once a subscription is cancelled record is still there. Once a subscription is cancelled
(individually, or as a result of the DSO session being closed) record (individually, or as a result of the DSO session being closed) record
aging for records covered by the subscription resumes and records are aging for records covered by the subscription resumes and records are
removed from the local cache when their TTL reaches zero. removed from the local cache when their TTL reaches zero.
6.4. DNS Push Notification UNSUBSCRIBE 6.4. DNS Push Notification UNSUBSCRIBE
To cancel an individual subscription without closing the entire DSO To cancel an individual subscription without closing the entire DSO
session, the client sends an UNSUBSCRIBE message over the established session, the client sends an UNSUBSCRIBE message over the established
DSO session to the server. The UNSUBSCRIBE message is encoded as a DSO session to the server. The UNSUBSCRIBE message is encoded as a
DSO unidirectional message [DSO]. This specification defines a DSO unidirectional message [RFC8490]. This specification defines a
primary unidirectional DSO TLV for DNS Push Notification UNSUBSCRIBE primary unidirectional DSO TLV for DNS Push Notification UNSUBSCRIBE
Messages (tentatively DSO Type Code 0x42). Messages (tentatively DSO Type Code 0x42).
A server MUST NOT initiate an UNSUBSCRIBE message. If a server does A server MUST NOT initiate an UNSUBSCRIBE message. If a server does
send an UNSUBSCRIBE message over a DSO session initiated by a client, send an UNSUBSCRIBE message over a DSO session initiated by a client,
this is a fatal error and the client should immediately abort the this is a fatal error and the client should immediately abort the
connection with a TCP RST (or equivalent for other protocols). connection with a TCP RST (or equivalent for other protocols).
6.4.1. UNSUBSCRIBE Message 6.4.1. UNSUBSCRIBE Message
An UNSUBSCRIBE unidirectional message begins with the standard DSO An UNSUBSCRIBE unidirectional message begins with the standard DSO
12-byte header [DSO], followed by the UNSUBSCRIBE primary TLV. An 12-byte header [RFC8490], followed by the UNSUBSCRIBE primary TLV.
UNSUBSCRIBE message is illustrated in Figure 3. An UNSUBSCRIBE message is illustrated in Figure 3.
In accordance with the definition of DSO unidirectional messages, the In accordance with the definition of DSO unidirectional messages, the
MESSAGE ID field MUST be zero. There is no server response to an MESSAGE ID field MUST be zero. There is no server response to an
UNSUBSCRIBE message. UNSUBSCRIBE message.
The other header fields MUST be set as described in the DSO The other header fields MUST be set as described in the DSO spec-
specification [DSO]. The DNS OPCODE field contains the OPCODE value ification [RFC8490]. The DNS OPCODE field contains the OPCODE value
for DNS Stateful Operations (6). The four count fields MUST be zero, for DNS Stateful Operations (6). The four count fields MUST be zero,
and the corresponding four sections MUST be empty (i.e., absent). and the corresponding four sections MUST be empty (i.e., absent).
The DSO-TYPE is UNSUBSCRIBE (tentatively 0x42). The DSO-TYPE is UNSUBSCRIBE (tentatively 0x42).
The DSO-LENGTH field contains the value 2, the length of the 2-octet The DSO-LENGTH field contains the value 2, the length of the 2-octet
MESSAGE ID contained in the DSO-DATA. MESSAGE ID contained in the DSO-DATA.
The DSO-DATA contains the value given in the MESSAGE ID field of an The DSO-DATA contains the value given in the MESSAGE ID field of an
active SUBSCRIBE request. This is how the server knows which active SUBSCRIBE request. This is how the server knows which
skipping to change at page 28, line 8 skipping to change at page 28, line 8
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 Message 6.5.1. RECONFIRM Message
A RECONFIRM unidirectional message begins with the standard DSO A RECONFIRM unidirectional message begins with the standard DSO
12-byte header [DSO], followed by the RECONFIRM primary TLV. A 12-byte header [RFC8490], followed by the RECONFIRM primary TLV.
RECONFIRM message is illustrated in Figure 4. A RECONFIRM message is illustrated in Figure 4.
In accordance with the definition of DSO unidirectional messages, the In accordance with the definition of DSO unidirectional messages, the
MESSAGE ID field MUST be zero. There is no server response to a MESSAGE ID field MUST be zero. There is no server response to a
RECONFIRM message. RECONFIRM message.
The other header fields MUST be set as described in the DSO The other header fields MUST be set as described in the DSO spec-
specification [DSO]. The DNS OPCODE field contains the OPCODE value ification [RFC8490]. The DNS OPCODE field contains the OPCODE value
for DNS Stateful Operations (6). The four count fields MUST be zero, for DNS Stateful Operations (6). The four count fields MUST be zero,
and the corresponding four sections MUST be empty (i.e., absent). and the corresponding four sections MUST be empty (i.e., absent).
The DSO-TYPE is RECONFIRM (tentatively 0x43). The DSO-TYPE is RECONFIRM (tentatively 0x43).
The DSO-LENGTH is the length of the data that follows, which The DSO-LENGTH is the length of the data that follows, which
specifies the name, type, class, and content of the record being specifies the name, type, class, and content of the record being
disputed. disputed.
1 1 1 1 1 1 1 1 1 1 1 1
skipping to change at page 30, line 8 skipping to change at page 30, line 8
DNS wildcarding is not supported. That is, a wildcard ("*") in a DNS wildcarding is not supported. That is, a wildcard ("*") in a
RECONFIRM message matches only a literal wildcard character ("*") in RECONFIRM message matches only a literal wildcard character ("*") in
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.
6.6. DNS Stateful Operations TLV Context Summary 6.6. DNS Stateful Operations TLV Context Summary
This document defines four new DSO TLVs. As suggested in Section 8.2 This document defines four new DSO TLVs. As suggested in Section 8.2
of the DNS Stateful Operations specification [DSO], the valid of the DNS Stateful Operations specification [RFC8490], the valid
contexts of these new TLV types are summarized below. contexts of these new TLV types are summarized below.
The client TLV contexts are: The client TLV contexts are:
C-P: Client request message, primary TLV C-P: Client request message, primary TLV
C-U: Client unidirectional message, primary TLV C-U: Client unidirectional message, primary TLV
C-A: Client request or unidirectional message, additional TLV C-A: Client request or unidirectional message, additional TLV
CRP: Response back to client, primary TLV CRP: Response back to client, primary TLV
CRA: Response back to client, additional TLV CRA: Response back to client, additional TLV
skipping to change at page 31, line 21 skipping to change at page 31, line 21
subscriptions on that DSO session (by ending the session) it is subscriptions on that DSO session (by ending the session) 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 session via UNSUBSCRIBE, After terminating its last subscription on a session via UNSUBSCRIBE,
a client MAY close the session immediately, or it may keep it open if a client MAY close the session immediately, or it may keep it open if
it anticipates performing further operations on that session in the it anticipates performing further operations on that session in the
future. If a client wishes to keep an idle session open, it MUST future. If a client wishes to keep an idle session open, it MUST
respect the maximum idle time required by the server [DSO]. respect the maximum idle time required by the server [RFC8490].
If a client plans to terminate one or more subscriptions on a session If a client plans to terminate one or more subscriptions on a session
and doesn't intend to keep that session open, then as an efficiency and doesn't intend to keep that session open, then as an efficiency
optimization it MAY instead choose to simply close the session, which optimization it MAY instead choose to simply close the session, which
implicitly terminates all subscriptions on that session. This may implicitly terminates all subscriptions on that session. This may
occur because the client computer is being shut down, is going to occur because the client computer is being shut down, is going to
sleep, the application requiring the subscriptions has terminated, or sleep, the application requiring the subscriptions has terminated, or
simply because the last active subscription on that session has been simply because the last active subscription on that session has been
cancelled. cancelled.
skipping to change at page 33, line 6 skipping to change at page 33, line 6
recommendations will continue to change. Updated versions or errata recommendations will continue to change. Updated versions or errata
may exist for these recommendations. may exist for these recommendations.
7.2. TLS Name Authentication 7.2. TLS Name Authentication
As described in Section 6.1, the client discovers the DNS Push As described in Section 6.1, the client discovers the DNS Push
Notification server using an SRV lookup for the record name Notification server using an SRV lookup for the record name
"_dns-push-tls._tcp.<zone>". The server connection endpoint SHOULD "_dns-push-tls._tcp.<zone>". The server connection endpoint SHOULD
then be authenticated using DANE TLSA records for the associated SRV then be authenticated using DANE TLSA records for the associated SRV
record. This associates the target's name and port number with a record. This associates the target's name and port number with a
trusted TLS certificate [RFC7673]. This procedure uses the TLS Sever trusted TLS certificate [RFC7673]. This procedure uses the TLS
Name Indication (SNI) extension [RFC6066] to inform the server of the Server Name Indication (SNI) extension [RFC6066] to inform the server
name the client has authenticated through the use of TLSA records. of the name the client has authenticated through the use of TLSA
Therefore, if the SRV record passes DNSSEC validation and a TLSA records. Therefore, if the SRV record passes DNSSEC validation and a
record matching the target name is useable, an SNI extension must be TLSA record matching the target name is useable, an SNI extension
used for the target name to ensure the client is connecting to the must be used for the target name to ensure the client is connecting
server it has authenticated. If the target name does not have a to the server it has authenticated. If the target name does not have
usable TLSA record, then the use of the SNI extension is optional. a usable TLSA record, then the use of the SNI extension is optional.
See Usage Profiles for DNS over TLS and DNS over DTLS [RFC8310] for See Usage Profiles for DNS over TLS and DNS over DTLS [RFC8310] for
more information on authenticating domain names. more information on authenticating domain names.
7.3. TLS Session Resumption 7.3. TLS Session Resumption
TLS Session Resumption is permissible on DNS Push Notification TLS Session Resumption is permissible on DNS Push Notification
servers. The server may keep TLS state with Session IDs [RFC8446] or servers. The server may keep TLS state with Session IDs [RFC8446] or
operate in stateless mode by sending a Session Ticket [RFC5077] to operate in stateless mode by sending a Session Ticket [RFC5077] to
the client for it to store. However, closing the TLS connection the client for it to store. However, closing the TLS connection
terminates the DSO session. When the TLS session is resumed, the DNS terminates the DSO session. When the TLS session is resumed, the DNS
skipping to change at page 34, line 31 skipping to change at page 34, line 31
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. Ted Lemon provided clarifying text Dickinson, and Andrew Sullivan. Ted Lemon provided clarifying text
that was greatly appreciated. that was greatly appreciated.
10. References 10. References
10.1. Normative References 10.1. Normative References
[DSO] Bellis, R., Cheshire, S., Dickinson, J., Dickinson, S.,
Lemon, T., and T. Pusateri, "DNS Stateful Operations",
draft-ietf-dnsop-session-signal-18 (work in progress),
October 2018.
[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-editor.org/info/rfc768>. <https://www.rfc-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,
<https://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,
skipping to change at page 35, line 20 skipping to change at page 35, line 15
[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-editor.org/info/rfc2119>. <https://www.rfc-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,
<https://www.rfc-editor.org/info/rfc2136>. <https://www.rfc-editor.org/info/rfc2136>.
[RFC2181] Elz, R. and R. Bush, "Clarifications to the DNS
Specification", RFC 2181, DOI 10.17487/RFC2181, July 1997,
<https://www.rfc-editor.org/info/rfc2181>.
[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-editor.org/info/rfc2782>. <https://www.rfc-editor.org/info/rfc2782>.
[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-editor.org/info/rfc6066>. <https://www.rfc-editor.org/info/rfc6066>.
skipping to change at page 36, line 13 skipping to change at page 36, line 9
<https://www.rfc-editor.org/info/rfc7766>. <https://www.rfc-editor.org/info/rfc7766>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>. <https://www.rfc-editor.org/info/rfc8446>.
[RFC8490] Bellis, R., Cheshire, S., Dickinson, J., Dickinson, S.,
Lemon, T., and T. Pusateri, "DNS Stateful Operations",
RFC 8490, DOI 10.17487/RFC8490, March 2019,
<https://www.rfc-editor.org/info/rfc8490>.
[ST] "Service Name and Transport Protocol Port Number [ST] "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/>.
10.2. Informative References 10.2. Informative References
[DisProx] Cheshire, S., "Discovery Proxy for Multicast DNS-Based [DisProx] Cheshire, S., "Discovery Proxy for Multicast DNS-Based
Service Discovery", draft-ietf-dnssd-hybrid-08 (work in Service Discovery", draft-ietf-dnssd-hybrid-10 (work in
progress), March 2018. progress), March 2019.
[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.
[LLQ] Sekar, K., "DNS Long-Lived Queries", draft-sekar-dns- [LLQ] Cheshire, S. and M. Krochmal, "DNS Long-Lived Queries",
llq-01 (work in progress), August 2006. draft-sekar-dns-llq-03 (work in progress), March 2019.
[obs] "Observer Pattern", [obs] "Observer Pattern",
<https://en.wikipedia.org/wiki/Observer_pattern>. <https://en.wikipedia.org/wiki/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,
<https://www.rfc-editor.org/info/rfc2308>. <https://www.rfc-editor.org/info/rfc2308>.
[RFC3123] Koch, P., "A DNS RR Type for Lists of Address Prefixes [RFC3123] Koch, P., "A DNS RR Type for Lists of Address Prefixes
(APL RR)", RFC 3123, DOI 10.17487/RFC3123, June 2001, (APL RR)", RFC 3123, DOI 10.17487/RFC3123, June 2001,
 End of changes. 50 change blocks. 
126 lines changed or deleted 134 lines changed or added

This html diff was produced by rfcdiff 1.47. The latest version is available from http://tools.ietf.org/tools/rfcdiff/