draft-ietf-simple-message-sessions-10.txt   draft-ietf-simple-message-sessions-11.txt 
SIMPLE WG B. Campbell, Ed. SIMPLE WG B. Campbell, Ed.
Internet-Draft Estacado Systems Internet-Draft Estacado Systems
Expires: August 24, 2005 R. Mahy, Ed. Expires: January 17, 2006 R. Mahy, Ed.
Airespace blankespace
C. Jennings, Ed. C. Jennings, Ed.
Cisco Systems, Inc. Cisco Systems, Inc.
February 20, 2005 July 16, 2005
The Message Session Relay Protocol The Message Session Relay Protocol
draft-ietf-simple-message-sessions-10.txt draft-ietf-simple-message-sessions-11.txt
Status of this Memo Status of this Memo
This document is an Internet-Draft and is subject to all provisions By submitting this Internet-Draft, each author represents that any
of Section 3 of RFC 3667. By submitting this Internet-Draft, each applicable patent or other IPR claims of which he or she is aware
author represents that any applicable patent or other IPR claims of have been or will be disclosed, and any of which he or she becomes
which he or she is aware have been or will be disclosed, and any of aware will be disclosed, in accordance with Section 6 of BCP 79.
which he or she become aware will be disclosed, in accordance with
RFC 3668.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as other groups may also distribute working documents as Internet-
Internet-Drafts. Drafts.
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."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on August 24, 2005. This Internet-Draft will expire on January 17, 2006.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2005). Copyright (C) The Internet Society (2005).
Abstract Abstract
This document describes the Message Session Relay Protocol (MSRP), a This document describes the Message Session Relay Protocol, a
protocol for transmitting a series of related instant messages in the protocol for transmitting a series of related instant messages in the
context of a session. Message sessions are treated like any other context of a session. Message sessions are treated like any other
media stream when setup via a rendezvous or session setup protocol media stream when setup via a rendezvous or session setup protocol
such as the Session Initiation Protocol (SIP). such as the Session Initiation Protocol.
Table of Contents Table of Contents
1. Conventions . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Introduction and Background . . . . . . . . . . . . . . . . 4 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Applicability of MSRP . . . . . . . . . . . . . . . . . . . 5 3. Applicability of MSRP . . . . . . . . . . . . . . . . . . . 5
4. Protocol Overview . . . . . . . . . . . . . . . . . . . . . 6 4. Protocol Overview . . . . . . . . . . . . . . . . . . . . . 6
5. Key Concepts . . . . . . . . . . . . . . . . . . . . . . . . 8 5. Key Concepts . . . . . . . . . . . . . . . . . . . . . . . . 9
5.1 MSRP Framing and Message Chunking . . . . . . . . . . . . 8 5.1 MSRP Framing and Message Chunking . . . . . . . . . . . . 9
5.2 MSRP Addressing . . . . . . . . . . . . . . . . . . . . . 9 5.2 MSRP Addressing . . . . . . . . . . . . . . . . . . . . . 10
5.3 MSRP Transaction and Report Model . . . . . . . . . . . . 10 5.3 MSRP Transaction and Report Model . . . . . . . . . . . . 10
5.4 MSRP Connection Model . . . . . . . . . . . . . . . . . . 11 5.4 MSRP Connection Model . . . . . . . . . . . . . . . . . . 12
6. MSRP URLs . . . . . . . . . . . . . . . . . . . . . . . . . 12 6. MSRP URLs . . . . . . . . . . . . . . . . . . . . . . . . . 14
6.1 MSRP URL Comparison . . . . . . . . . . . . . . . . . . . 14 6.1 MSRP URL Comparison . . . . . . . . . . . . . . . . . . . 15
6.2 Resolving MSRP Host Device . . . . . . . . . . . . . . . . 14 6.2 Resolving MSRP Host Device . . . . . . . . . . . . . . . . 15
7. Method-Specific Behavior . . . . . . . . . . . . . . . . . . 15 7. Method-Specific Behavior . . . . . . . . . . . . . . . . . . 16
7.1 Constructing Requests . . . . . . . . . . . . . . . . . . 15 7.1 Constructing Requests . . . . . . . . . . . . . . . . . . 16
7.1.1 Delivering SEND requests . . . . . . . . . . . . . . . 16 7.1.1 Sending SEND requests . . . . . . . . . . . . . . . . 17
7.1.2 Sending REPORT requests . . . . . . . . . . . . . . . 18 7.1.2 Sending REPORT requests . . . . . . . . . . . . . . . 20
7.1.3 Failure REPORT Generation . . . . . . . . . . . . . . 19 7.1.3 Failure REPORT Generation . . . . . . . . . . . . . . 21
7.2 Constructing Responses . . . . . . . . . . . . . . . . . . 20 7.2 Constructing Responses . . . . . . . . . . . . . . . . . . 22
7.3 Receiving Requests . . . . . . . . . . . . . . . . . . . . 21 7.3 Receiving Requests . . . . . . . . . . . . . . . . . . . . 23
7.3.1 Receiving SEND requests . . . . . . . . . . . . . . . 21 7.3.1 Receiving SEND requests . . . . . . . . . . . . . . . 23
7.3.2 Receiving REPORT requests . . . . . . . . . . . . . . 22 7.3.2 Receiving REPORT requests . . . . . . . . . . . . . . 25
8. Using MSRP with SIP . . . . . . . . . . . . . . . . . . . . 23 8. Using MSRP with SIP . . . . . . . . . . . . . . . . . . . . 26
8.1 SDP Offer-Answer Exchanges for MSRP Sessions . . . . . . . 23 8.1 SDP Offer-Answer Exchanges for MSRP Sessions . . . . . . . 26
8.1.1 URL Negotiations . . . . . . . . . . . . . . . . . . . 25 8.1.1 URL Negotiations . . . . . . . . . . . . . . . . . . . 28
8.1.2 Path Attributes with Multiple URLs . . . . . . . . . . 26 8.1.2 Path Attributes with Multiple URLs . . . . . . . . . . 29
8.1.3 SDP Connection and Media Lines . . . . . . . . . . . . 27 8.1.3 SDP Connection and Media Lines . . . . . . . . . . . . 30
8.1.4 Updated SDP Offers . . . . . . . . . . . . . . . . . . 28 8.1.4 Updated SDP Offers . . . . . . . . . . . . . . . . . . 30
8.1.5 Example SDP Exchange . . . . . . . . . . . . . . . . . 28 8.1.5 Example SDP Exchange . . . . . . . . . . . . . . . . . 31
8.1.6 Connection Negotiation . . . . . . . . . . . . . . . . 29 8.1.6 Connection Negotiation . . . . . . . . . . . . . . . . 31
8.2 MSRP User Experience with SIP . . . . . . . . . . . . . . 29 8.2 MSRP User Experience with SIP . . . . . . . . . . . . . . 32
9. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . 30 9. Formal Syntax . . . . . . . . . . . . . . . . . . . . . . . 32
10. Response Code Descriptions . . . . . . . . . . . . . . . . . 32 10. Response Code Descriptions . . . . . . . . . . . . . . . . . 35
10.1 200 . . . . . . . . . . . . . . . . . . . . . . . . . . 32 10.1 200 . . . . . . . . . . . . . . . . . . . . . . . . . . 35
10.2 400 . . . . . . . . . . . . . . . . . . . . . . . . . . 32 10.2 400 . . . . . . . . . . . . . . . . . . . . . . . . . . 35
10.3 403 . . . . . . . . . . . . . . . . . . . . . . . . . . 32 10.3 403 . . . . . . . . . . . . . . . . . . . . . . . . . . 35
10.4 408 . . . . . . . . . . . . . . . . . . . . . . . . . . 32 10.4 408 . . . . . . . . . . . . . . . . . . . . . . . . . . 35
10.5 413 . . . . . . . . . . . . . . . . . . . . . . . . . . 33 10.5 413 . . . . . . . . . . . . . . . . . . . . . . . . . . 35
10.6 415 . . . . . . . . . . . . . . . . . . . . . . . . . . 33 10.6 415 . . . . . . . . . . . . . . . . . . . . . . . . . . 36
10.7 423 . . . . . . . . . . . . . . . . . . . . . . . . . . 33 10.7 423 . . . . . . . . . . . . . . . . . . . . . . . . . . 36
10.8 426 . . . . . . . . . . . . . . . . . . . . . . . . . . 33 10.8 426 . . . . . . . . . . . . . . . . . . . . . . . . . . 36
10.9 481 . . . . . . . . . . . . . . . . . . . . . . . . . . 33 10.9 481 . . . . . . . . . . . . . . . . . . . . . . . . . . 36
10.10 501 . . . . . . . . . . . . . . . . . . . . . . . . . . 33 10.10 501 . . . . . . . . . . . . . . . . . . . . . . . . . . 36
10.11 506 . . . . . . . . . . . . . . . . . . . . . . . . . . 33 10.11 506 . . . . . . . . . . . . . . . . . . . . . . . . . . 36
11. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 34 11. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 36
11.1 Basic IM session . . . . . . . . . . . . . . . . . . . . 34 11.1 Basic IM session . . . . . . . . . . . . . . . . . . . . 37
11.2 Message with XHTML Content . . . . . . . . . . . . . . . 36 11.2 Message with XHTML Content . . . . . . . . . . . . . . . 39
11.3 Chunked Message . . . . . . . . . . . . . . . . . . . . 36 11.3 Chunked Message . . . . . . . . . . . . . . . . . . . . 39
11.4 System Message . . . . . . . . . . . . . . . . . . . . . 36 11.4 System Message . . . . . . . . . . . . . . . . . . . . . 39
11.5 Positive Report . . . . . . . . . . . . . . . . . . . . 37 11.5 Positive Report . . . . . . . . . . . . . . . . . . . . 40
11.6 Forked IM . . . . . . . . . . . . . . . . . . . . . . . 37 11.6 Forked IM . . . . . . . . . . . . . . . . . . . . . . . 40
12. Extensibility . . . . . . . . . . . . . . . . . . . . . . . 40 12. Extensibility . . . . . . . . . . . . . . . . . . . . . . . 44
13. CPIM compatibility . . . . . . . . . . . . . . . . . . . . . 40 13. CPIM compatibility . . . . . . . . . . . . . . . . . . . . . 44
14. Security Considerations . . . . . . . . . . . . . . . . . . 41 14. Security Considerations . . . . . . . . . . . . . . . . . . 45
14.1 Transport Level Protection . . . . . . . . . . . . . . . 42 14.1 Transport Level Protection . . . . . . . . . . . . . . . 45
14.2 S/MIME . . . . . . . . . . . . . . . . . . . . . . . . . 43 14.2 S/MIME . . . . . . . . . . . . . . . . . . . . . . . . . 46
14.3 Other Security Concerns . . . . . . . . . . . . . . . . 44 14.3 Other Security Concerns . . . . . . . . . . . . . . . . 47
15. IANA Considerations . . . . . . . . . . . . . . . . . . . . 45 15. IANA Considerations . . . . . . . . . . . . . . . . . . . . 49
15.1 MSRP Port . . . . . . . . . . . . . . . . . . . . . . . 45 15.1 MSRP Method Names . . . . . . . . . . . . . . . . . . . 49
15.2 MSRP URL Schemes . . . . . . . . . . . . . . . . . . . . 45 15.2 MSRP Header Fields . . . . . . . . . . . . . . . . . . . 49
15.3 SDP Transport Protocol . . . . . . . . . . . . . . . . . 46 15.3 MSRP Status Codes . . . . . . . . . . . . . . . . . . . 50
15.4 SDP Attribute Names . . . . . . . . . . . . . . . . . . 46 15.4 MSRP Port . . . . . . . . . . . . . . . . . . . . . . . 50
15.4.1 Accept Types . . . . . . . . . . . . . . . . . . . . 46 15.5 MSRP URL Schemes . . . . . . . . . . . . . . . . . . . . 50
15.4.2 Wrapped Types . . . . . . . . . . . . . . . . . . . 46 15.6 SDP Transport Protocol . . . . . . . . . . . . . . . . . 50
15.4.3 Max Size . . . . . . . . . . . . . . . . . . . . . . 47 15.7 SDP Attribute Names . . . . . . . . . . . . . . . . . . 51
15.4.4 Path . . . . . . . . . . . . . . . . . . . . . . . . 47 15.7.1 Accept Types . . . . . . . . . . . . . . . . . . . . 51
16. Change History . . . . . . . . . . . . . . . . . . . . . . . 47 15.7.2 Wrapped Types . . . . . . . . . . . . . . . . . . . 51
16.1 draft-ietf-simple-message-sessions-10 . . . . . . . . . 47 15.7.3 Max Size . . . . . . . . . . . . . . . . . . . . . . 51
16.2 draft-ietf-simple-message-sessions-09 . . . . . . . . . 48 15.7.4 Path . . . . . . . . . . . . . . . . . . . . . . . . 52
16.3 draft-ietf-simple-message-sessions-08 . . . . . . . . . 48 16. Contributors and Acknowledgments . . . . . . . . . . . . . . 52
16.4 draft-ietf-simple-message-sessions-07 . . . . . . . . . 49 17. References . . . . . . . . . . . . . . . . . . . . . . . . . 52
16.5 draft-ietf-simple-message-sessions-06 . . . . . . . . . 49 17.1 Normative References . . . . . . . . . . . . . . . . . . 52
16.6 draft-ietf-simple-message-sessions-05 . . . . . . . . . 50 17.2 Informational References . . . . . . . . . . . . . . . . 53
16.7 draft-ietf-simple-message-sessions-04 . . . . . . . . . 50
16.8 draft-ietf-simple-message-sessions-03 . . . . . . . . . 50
16.9 draft-ietf-simple-message-sessions-02 . . . . . . . . . 51
16.10 draft-ietf-simple-message-sessions-01 . . . . . . . . . 51
16.11 draft-ietf-simple-message-sessions-00 . . . . . . . . . 51
16.12 draft-campbell-simple-im-sessions-01 . . . . . . . . . . 52
17. Contributors and Acknowledgments . . . . . . . . . . . . . . 52
18. References . . . . . . . . . . . . . . . . . . . . . . . . . 52
18.1 Normative References . . . . . . . . . . . . . . . . . . 52
18.2 Informational References . . . . . . . . . . . . . . . . 53
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 55 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 55
Intellectual Property and Copyright Statements . . . . . . . 56 Intellectual Property and Copyright Statements . . . . . . . 56
1. Conventions 1. Introduction
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [5].
This document consistently refers to a "message" as a complete unit
of MIME or text content. In some cases a message is split and
delivered in more than one MSRP request. Each of these portions of
the complete message is called a "chunk".
2. Introduction and Background
A series of related instant messages between two or more parties can A series of related instant messages between two or more parties can
be viewed as part of a "message session", that is, a conversational be viewed as part of a "message session", that is, a conversational
exchange of messages with a definite beginning and end. This is in exchange of messages with a definite beginning and end. This is in
contrast to individual messages each sent completely independently. contrast to individual messages each sent completely independently.
The SIMPLE Working Group describes messaging schemes that only track Messaging schemes that only track individual messages can be
individual messages as "page-mode" messages, whereas messaging that described as "page-mode" messaging, whereas messaging that is part of
is part of a "session" with a definite start and end is called a "session" with a definite start and end is called "session-mode"
"session-mode" messaging. messaging.
Page-mode messaging is enabled in SIMPLE via the SIP [4]MESSAGE Page-mode messaging is enabled in SIP via the SIP [4] MESSAGE method
method [18]. Session-mode messaging has a number of benefits [19] [19]. Session-mode messaging has a number of benefits [20] over
over page-mode messaging however, such as explicit rendezvous, page-mode messaging however, such as explicit rendezvous, tighter
tighter integration with other media types, direct client-to-client integration with other media types, direct client-to-client
operation, and brokered privacy and security. operation, and brokered privacy and security.
This document defines a session-oriented instant message transport This document defines a session-oriented instant message transport
protocol called the Message Session Relay Protocol (MSRP), whose protocol called the Message Session Relay Protocol (MSRP), whose
sessions can be included in an offer or answer [3] using the Session sessions can be negotiated with an offer or answer [3] using the
Description Protocol(SDP [2]). The exchange is carried by some Session Description Protocol(SDP [2]). The exchange is carried by
signaling protocol, such as the Session Initiation Protocol (SIP some signaling protocol, such as the Session Initiation Protocol (SIP
[4]). This allows a communication user agent to offer a messaging [4]). This allows a communication user agent to offer a messaging
session as one of the possible media types in a session. For session as one of the possible media types in a session. For
instance, Alice may want to communicate with Bob. Alice doesn't know instance, Alice may want to communicate with Bob. Alice doesn't know
at the moment whether Bob has his phone or his IM client handy, but at the moment whether Bob has his phone or his IM client handy, but
she's willing to use either. She sends an invitation to a session to she's willing to use either. She sends an invitation to a session to
the address of record she has for Bob, sip:bob@example.com. Her the address of record she has for Bob, sip:bob@example.com. Her
invitation offers both voice and an IM session. The SIP services at invitation offers both voice and an IM session. The SIP services at
example.com forward the invitation to Bob at his currently registered example.com forward the invitation to Bob at his currently registered
clients. Bob accepts the invitation at his IM client and they begin clients. Bob accepts the invitation at his IM client and they begin
a threaded chat conversation. a threaded chat conversation.
When a user uses an IM URL, other documents define how DNS can be When a user uses an IM URL, RFC 3861 [31] defines how DNS can be used
used to map this to a particular protocol to establish the session to map this to a particular protocol to establish the session such as
such as SIP. SIP can use an offer answer model to transport the MSRP SIP. SIP can use an offer answer model to transport the MSRP URLs
URLs for the media in SDP. This document defines how the for the media in SDP. This document defines how the offer-answer
offer-answer exchange works to establish MSRP connections and how exchange works to establish MSRP connections and how messages are
messages are sent across the MSRP protocol but it does not deal with sent across the MSRP protocol but it does not deal with the issues of
the issues of mapping an IM URL to a session establishment protocol. mapping an IM URL to a session establishment protocol.
This session model allows message sessions to be integrated into This session model allows message sessions to be integrated into
advanced communications applications with little to no additional advanced communications applications with little to no additional
protocol development. For example, during the above chat session, protocol development. For example, during the above chat session,
Bob decides Alice really needs to be talking to Carol. Bob can Bob decides Alice really needs to be talking to Carol. Bob can
transfer [17] Alice to Carol, introducing them into their own transfer [18] Alice to Carol, introducing them into their own
messaging session. Messaging sessions can then be easily integrated messaging session. Messaging sessions can then be easily integrated
into call-center and dispatch environments utilizing third-party call into call-center and dispatch environments utilizing third-party call
control [16] and conferencing [15] applications. control [17] and conferencing [16] applications.
This document specifies MSRP behavior only for peer-to-peer sessions,
that is, sessions crossing only a single hop. However, work to
specify behavior for MSRP relay devices [21] (referred to herein as
"relays") is occurring as a separate effort.
2. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [5].
This document consistently refers to a "message" as a complete unit
of MIME or text content. In some cases a message is split and
delivered in more than one MSRP request. Each of these portions of
the complete message is called a "chunk".
3. Applicability of MSRP 3. Applicability of MSRP
MSRP is not designed for use as a standalone protocol. MSRP MUST be MSRP is not designed for use as a standalone protocol. MSRP MUST be
used only in the context of a rendezvous mechanism meeting the used only in the context of a rendezvous mechanism meeting the
following requirements: following requirements:
The rendezvous mechanism MUST provide both MSRP URLs associated The rendezvous mechanism MUST provide both MSRP URLs associated
with an MSRP session to each of the participating endpoints. The with an MSRP session to each of the participating endpoints. The
rendezvous mechanism MUST implement mechanisms to provide these rendezvous mechanism MUST implement mechanisms to provide these
URLs securely - they MUST NOT be made available to an untrusted URLs securely - they MUST NOT be made available to an untrusted
third party or be easily discoverable. third party or be easily discoverable.
The rendezvous mechanism MUST provide mechanisms for the The rendezvous mechanism MUST provide mechanisms for the
negotiation of any supported MSRP extensions that are not negotiation of any supported MSRP extensions that are not
backwards compatible. backwards compatible.
The rendezvous mechanism MUST be able to natively transport im: The rendezvous mechanism MUST be able to natively transport im:
URIs or automatically translate im: URIs [24] into the addressing URIs or automatically translate im: URIs [25] into the addressing
identifiers of the rendezvous protocol. identifiers of the rendezvous protocol.
To use a rendezvous mechanism with MSRP, an RFC must be prepared To use a rendezvous mechanism with MSRP, an RFC must be prepared
describing how it exchanges MSRP URIs and meets these requirements describing how it exchanges MSRP URLs and meets these requirements
listed here. This document provides such a description for the use listed here. This document provides such a description for the use
of MSRP in the context of SIP and SDP. of MSRP in the context of SIP and SDP.
SIP meets these requirements for a rendezvous mechanism. The MSRP SIP meets these requirements for a rendezvous mechanism. The MSRP
URLs are exchanged using SDP in an offer/answer exchange via SIP. URLs are exchanged using SDP in an offer/answer exchange via SIP.
The exchanged SDP can also be used to negotiate MSRP extensions. The exchanged SDP can also be used to negotiate MSRP extensions.
This SDP can be secured using any of the mechanisms available in SIP, This SDP can be secured using any of the mechanisms available in SIP,
including using the sips mechanism to ensure transport security including using the sips mechanism to ensure transport security
across intermediaries and S/MIME for end-to-end protection of the SDP across intermediaries and S/MIME for end-to-end protection of the SDP
entity. SIP can carry arbitrary URIs (including im: URIs) in the entity. SIP can carry arbitrary URIs (including im: URIs) in the
skipping to change at page 6, line 14 skipping to change at page 6, line 19
4. Protocol Overview 4. Protocol Overview
MSRP is a text-based, connection-oriented protocol for exchanging MSRP is a text-based, connection-oriented protocol for exchanging
arbitrary (binary) MIME content, especially instant messages. This arbitrary (binary) MIME content, especially instant messages. This
section is a non-normative overview of how MSRP works and how it is section is a non-normative overview of how MSRP works and how it is
used with SIP. used with SIP.
MSRP sessions are typically arranged using SIP the same way a session MSRP sessions are typically arranged using SIP the same way a session
of audio or video media is setup. One SIP user agent (Alice) sends of audio or video media is setup. One SIP user agent (Alice) sends
the other (Bob) a SIP invitation containing an offered the other (Bob) a SIP invitation containing an offered session-
session-description which includes a session of MSRP. The receiving description which includes a session of MSRP. The receiving SIP user
SIP user agent can accept the invitation and include an answer agent can accept the invitation and include answer session-
session-description which acknowledges the choice of media. Alice's description which acknowledges the choice of media. Alice's session
session description contains an MSRP URL that describes where she is description contains an MSRP URL that describes where she is willing
willing to receive MSRP requests from Bob, and vice-versa. (Note: to receive MSRP requests from Bob, and vice-versa. (Note: Some lines
Some lines in the examples are removed for clarity and brevity.) in the examples are removed for clarity and brevity.)
Alice sends to Bob: Alice sends to Bob:
INVITE sip:alice@atlanta.example.com SIP/2.0 INVITE sip:bob@atlanta.example.com SIP/2.0
To: <sip:bob@biloxi.example.com> To: <sip:bob@biloxi.example.com>
From: <sip:alice@atlanta.example.com>;tag=786 From: <sip:alice@atlanta.example.com>;tag=786
Call-ID: 3413an89KU Call-ID: 3413an89KU
Content-Type: application/sdp Content-Type: application/sdp
c=IN IP4 atlanta.example.com c=IN IP4 atlanta.example.com
m=message 7654 msrp/tcp * m=message 7654 TCP/MSRP *
a=accept-types:text/plain a=accept-types:text/plain
a=path:msrp://atlanta.example.com:7654/jshA7we;tcp a=path:msrp://atlanta.example.com:7654/jshA7we;tcp
Bob sends to Alice: Bob sends to Alice:
SIP/2.0 200 OK SIP/2.0 200 OK
To: <sip:bob@biloxi.example.com>;tag=087js To: <sip:bob@biloxi.example.com>;tag=087js
From: <sip:alice@atlanta.example.com>;tag=786 From: <sip:alice@atlanta.example.com>;tag=786
Call-ID: 3413an89KU Call-ID: 3413an89KU
Content-Type: application/sdp Content-Type: application/sdp
c=IN IP4 biloxi.example.com c=IN IP4 biloxi.example.com
m=message 12763 msrp/tcp * m=message 12763 TCP/MSRP *
a=accept-types:text/plain a=accept-types:text/plain
a=path:msrp://biloxi.example.com:12763/kjhd37s2s2;tcp a=path:msrp://biloxi.example.com:12763/kjhd37s2s2;tcp
Alice sends to Bob: Alice sends to Bob:
ACK sip:alice@atlanta.example.com SIP/2.0 ACK sip:bob@atlanta.example.com SIP/2.0
To: <sip:bob@biloxi.example.com>;tag=087js To: <sip:bob@biloxi.example.com>;tag=087js
From: <sip:alice@atlanta.example.com>;tag=786 From: <sip:alice@atlanta.example.com>;tag=786
Call-ID: 3413an89KU Call-ID: 3413an89KU
MSRP defines two request types, or methods. SEND requests are used MSRP defines two request types, or methods. SEND requests are used
to deliver a complete message or a chunk (a portion of a complete to deliver a complete message or a chunk (a portion of a complete
message), while REPORT requests report on the status of an earlier message), while REPORT requests report on the status of a previously
SEND request. When Alice receives Bob's answer, she checks to see if sent message, or a range of bytes inside a message. When Alice
she has an existing connection to Bob. If not, she opens a new receives Bob's answer, she checks to see if she has an existing
connection to Bob using the URL he provided in the SDP. Alice then connection to Bob. If not, she opens a new connection to Bob using
delivers a SEND request to Bob with her initial message, and Bob the URL he provided in the SDP. Alice then delivers a SEND request
replies indicating that Alice's request was received successfully. to Bob with her initial message, and Bob replies indicating that
Alice's request was received successfully.
MSRP a786hjs2 SEND MSRP a786hjs2 SEND
To-Path: msrp://biloxi.example.com:12763/kjhd37s2s2;tcp To-Path: msrp://biloxi.example.com:12763/kjhd37s2s2;tcp
From-Path: msrp://atlanta.example.com:7654/jshA7we;tcp From-Path: msrp://atlanta.example.com:7654/jshA7we;tcp
Message-ID: 87652 Message-ID: 87652
Byte-Range: 1-25/25 Byte-Range: 1-25/25
Content-Type: text/plain Content-Type: text/plain
Hey Bob, are you there? Hey Bob, are you there?
-------a786hjs2$ -------a786hjs2$
MSRP a786hjs2 200 OK MSRP a786hjs2 200 OK
To-Path: msrp://atlanta.example.com:7654/jshA7we;tcp To-Path: msrp://atlanta.example.com:7654/jshA7we;tcp
From-Path: msrp://biloxi.example.com:12763/kjhd37s2s2;tcp From-Path: msrp://biloxi.example.com:12763/kjhd37s2s2;tcp
Message-ID: 87652 Message-ID: 87652
Byte-Range: 1-25/25 Byte-Range: 1-25/25
-------a786hjs2$ -------a786hjs2$
Alice's request begins with the MSRP start line, which contains a Alice's request begins with the MSRP start line, which contains a
transaction identifier that is also used as a final boundary marker. transaction identifier that is also used for request framing. Next
Next she includes the path of URLs to the destination in the To-Path she includes the path of URLs to the destination in the To-Path
header, and her own URL in the From-Path header. In this typical header, and her own URL in the From-Path header. In this typical
case there is just one "hop", so there is only one URL in each path case there is just one "hop", so there is only one URL in each path
header field. She also includes a message ID which she can use to header field. She also includes a message ID which she can use to
correlate responses and status reports with the original message. correlate responses and status reports with the original message.
Next she puts the actual content. Finally she closes the request Next she puts the actual content. Finally she closes the request
with an end line: seven hyphens, the transaction identifier / with an end-line seven hyphens, the transaction identifier and a "$"
boundary marker and a "$" to indicate this request contains the end to indicate this request contains the end of a complete message.
of a complete message.
If Alice wants to deliver a very large message, she can split the If Alice wants to deliver a very large message, she can split the
message into chunks and deliver each chunk in a separate SEND message into chunks and deliver each chunk in a separate SEND
request. The message ID corresponds to the whole message, so the request. The message ID corresponds to the whole message, so the
receiver can also use it to reassemble the message and tell which receiver can also use it to reassemble the message and tell which
chunks belong with which message. Chunking is described in more chunks belong with which message. Chunking is described in more
detail in Section 5.1. The Byte-Range header identifies the portion detail in Section 5.1. The Byte-Range header identifies the portion
of the message carried in this chunk and the total size of the of the message carried in this chunk and the total size of the
message. message.
skipping to change at page 8, line 21 skipping to change at page 9, line 9
requesting types of reports and errors is described in Section 5.3. requesting types of reports and errors is described in Section 5.3.
Alice and Bob generally choose their MSRP URLs in such a way that is Alice and Bob generally choose their MSRP URLs in such a way that is
difficult to guess the exact URL. Alice and Bob can reject requests difficult to guess the exact URL. Alice and Bob can reject requests
to URLs they are not expecting to service, and can correlate the to URLs they are not expecting to service, and can correlate the
specific URL with the probable sender. Alice and Bob can also use specific URL with the probable sender. Alice and Bob can also use
TLS [1] to provide channel security over this hop. To receive MSRP TLS [1] to provide channel security over this hop. To receive MSRP
requests over a TLS protected connection, Alice or Bob could requests over a TLS protected connection, Alice or Bob could
advertise URLs with the "msrps" scheme instead of "msrp." advertise URLs with the "msrps" scheme instead of "msrp."
This document specifies MSRP behavior only for peer-to-peer sessions, MSRP is designed with the expectation that MSRP can carry URLs for
that is, sessions crossing only a single hop. However, work to nodes on the far side of relays. For this reason, a URL with the
specify behavior for MSRP relay devices [20] (referred to herein as "msrps" scheme makes no assertion about the security properties of
"relays") is occurring as a separate effort. MSRP is designed with other hops, just the next hop. The user agent knows the URL for each
the expectation that MSRP can carry URLs for nodes on the far side of hop, so it can verify that each URL has the desired security
such relays. For this reason, a URL with the "msrps" scheme makes no properties.
assertion about the security properties of other hops, just the next
hop. The user agent knows the URL for each hop, so it can verify
that each URL has the desired security properties.
MSRP URLs are discussed in more detail in Section 6. MSRP URLs are discussed in more detail in Section 6.
An adjacent pair of busy MSRP nodes (for example two relays) can An adjacent pair of busy MSRP nodes (for example two relays) can
easily have several sessions, and exchange traffic for several easily have several sessions, and exchange traffic for several
simultaneous users. The nodes can use existing connections to carry simultaneous users. The nodes can use existing connections to carry
new traffic with the same destination host, port, transport protocol, new traffic with the same destination host, port, transport protocol,
and scheme. MSRP nodes can keep track of how many sessions are using and scheme. MSRP nodes can keep track of how many sessions are using
a particular connection and close these connections when no sessions a particular connection and close these connections when no sessions
have used them for some period of time. Connection management is have used them for some period of time. Connection management is
discussed in more detail in Section 5.4. discussed in more detail in Section 5.4.
5. Key Concepts 5. Key Concepts
5.1 MSRP Framing and Message Chunking 5.1 MSRP Framing and Message Chunking
Messages sent using MSRP can be very large and can be delivered in Messages sent using MSRP can be very large and can be delivered in
several SEND requests, where each SEND request contains one chunk of several SEND requests, where each SEND request contains one chunk of
the overall message. Long chunks may be interrupted in the overall message. Long chunks may be interrupted in mid-
mid-transmission to ensure fairness across shared transport transmission to ensure fairness across shared transport connections.
connections. To support this, MSRP uses a boundary based framing To support this, MSRP uses a boundary based framing mechanism. The
mechanism. The start line of an MSRP request contains a unique start line of an MSRP request contains a unique identifier that is
boundary string that is used to indicate the end of the request. also used to indicate the end of the request. Included at the end of
Following the boundary string at the end of the body data, there is a the end-line, there is a flag that indicates whether this is the last
flag that indicates whether this is the last chunk of data for this chunk of data for this message or whether the message will be
message or whether the message will be continued in a subsequent continued in a subsequent chunk. There is also a Byte-Range header
chunk. There is also a Byte-Range header in the request that in the request that indicates the overall position of this chunk
indicates the overall position of this chunk inside the complete inside the complete message.
message.
For example, the following snippet of two SEND requests demonstrates For example, the following snippet of two SEND requests demonstrates
a message that contains the text "abcdEFGH" being sent as two chunks. a message that contains the text "abcdEFGH" being sent as two chunks.
MSRP dkei38sd SEND MSRP dkei38sd SEND
Message-ID: 456 Message-ID: 456
Byte-Range: 1-4/8 Byte-Range: 1-4/8
Content-Type: text/plain Content-Type: text/plain
abcd abcd
skipping to change at page 10, line 11 skipping to change at page 10, line 46
provide a complete path to the end recipient. When two MSRP nodes provide a complete path to the end recipient. When two MSRP nodes
communicate directly they need only one URL in the To-Path list and communicate directly they need only one URL in the To-Path list and
one URL in the From-Path list. one URL in the From-Path list.
5.3 MSRP Transaction and Report Model 5.3 MSRP Transaction and Report Model
A sender sends MSRP requests to a receiver. The receiver MUST A sender sends MSRP requests to a receiver. The receiver MUST
quickly accept or reject the request. If the receiver initially quickly accept or reject the request. If the receiver initially
accepted the request, it still may then do things that take accepted the request, it still may then do things that take
significant time to succeed or fail. For example, if the receiver is significant time to succeed or fail. For example, if the receiver is
an MSRP to XMPP [28] gateway, it may forward the message over XMPP. an MSRP to XMPP [29] gateway, it may forward the message over XMPP.
The XMPP side may later indicate that the request did not work. At The XMPP side may later indicate that the request did not work. At
this point, the MSRP receiver may need to indicate that the request this point, the MSRP receiver may need to indicate that the request
did not succeed. There are two important concepts here: first, the did not succeed. There are two important concepts here: first, the
hop by hop delivery of the request may succeed or fail; second, the hop by hop delivery of the request may succeed or fail; second, the
end result of the request may be successfully processed or not. The end result of the request may be successfully processed or not. The
first type of status is referred to as "transaction status" and may first type of status is referred to as "transaction status" and may
be returned in response to a request. The second type of status is be returned in response to a request. The second type of status is
referred to as "request status" and may be returned in a REPORT referred to as "delivery status" and may be returned in a REPORT
transaction. transaction.
The original sender of a request can indicate if they wish to receive The original sender of a request can indicate if they wish to receive
reports for requests that fail, and can independently indicate if reports for requests that fail, and can independently indicate if
they wish to receive reports for requests that succeed. A receiver they wish to receive reports for requests that succeed. A receiver
only sends a success REPORT if it knows that the request succeeded, only sends a success REPORT if it knows that the request was
and the sender requested a success report. A receiver only sends a successfully delivered, and the sender requested a success report. A
failure REPORT if the request failed and the sender requested failure receiver only sends a failure REPORT if the request failed to be
reports. delivered and the sender requested failure reports.
This document describes the behavior of MSRP endpoints. MSRP This document describes the behavior of MSRP endpoints. MSRP
relays or gateways are likely to have additional conditions that relays or gateways are likely to have additional conditions that
indicate a failure REPORT should be sent, such as the failure to indicate a failure REPORT should be sent, such as the failure to
receive a positive response from the next hop. receive a positive response from the next hop.
Two header fields control the sender's desire to receive reports. Two header fields control the sender's desire to receive reports.
The header "Success-Report" can have a value of "yes" or "no" and the The header "Success-Report" can have a value of "yes" or "no" and the
"Failure-Report" header can have a value of "yes", "no", or "Failure-Report" header can have a value of "yes", "no", or
"partial". "partial".
The combinations of reporting are needed to meet the various The combinations of reporting are needed to meet the various
scenarios of currently deployed IM systems. Success-Report might be scenarios of currently deployed IM systems. Success-Report might be
"no" in many public systems to reduce load but is used in some "no" in many public systems to reduce load but might be "yes" in
current enterprise systems, such as systems used for securities certain enterprise systems, such as systems used for securities
trading. A Failure-Report value of "no" is useful for sending system trading. A Failure-Report value of "no" is useful for sending system
messages such as "the system is going down in 5 minutes" without messages such as "the system is going down in 5 minutes" without
causing a response explosion to the sender. A Failure-Report of causing a response explosion to the sender. A Failure-Report of
"yes" is used by many systems that wish to notify the user if the "yes" is used by many systems that wish to notify the user if the
message failed. A Failure-Report of "partial" is a way to report message failed. A Failure-Report of "partial" is a way to report
errors except timeouts. The timeout error reporting requires the errors other than timeouts. The timeout error reporting requires the
sending hop to run a timer and that receiving hop to send an sending hop to run a timer and the receiving hop to send an
acknowledgment to stop the timer. Some systems don't want the acknowledgment to stop the timer. Some systems don't want the
overhead of doing this so choose not to but still allow error overhead of doing this so choose not to but still allow error
responses to be sent in many cases and these systems can use responses to be sent in many cases and these systems can use
"partial". "partial".
The "partial" value allows a compromise between no reporting of
failures, and reporting all failures. For example, with
"partial", an sending device does not have keep transaction state
around waiting for a positive acknowledgement. But it still
allows devices to report other types of errors. For example, the
receiving device could still report a policy violation such as an
unacceptable content-type, or an ICMP error trying to connect to a
downstream device.
5.4 MSRP Connection Model 5.4 MSRP Connection Model
When MSRP wishes to send a request to a peer identified by an MSRP When MSRP wishes to send a request to a peer identified by an MSRP
URL, it first needs a transport connection, with the appropriate URL, it first needs a transport connection, with the appropriate
security properties, to the host specified in the URL. If the sender security properties, to the host specified in the URL. If the sender
already has such a connection, that is, one associated with the same already has such a connection, that is, one associated with the same
host, port, and URL scheme, then it SHOULD reuse that connection. host, port, and URL scheme, then it SHOULD reuse that connection.
When a new MSRP session is created, the offerer MUST act as the When a new MSRP session is created, the offerer MUST act as the
"active" endpoint, meaning that it is responsible for opening the "active" endpoint, meaning that it is responsible for opening the
transport connection to the answerer, if a new connection is transport connection to the answerer, if a new connection is
required. However, this requirement MAY be weakened if standardized required. However, this requirement MAY be weakened if standardized
mechanisms for negotiating the connection direction become available, mechanisms for negotiating the connection direction become available,
and is implemented by both parties to the connection. and is implemented by both parties to the connection.
Likewise, the active endpoint MUST immediately issue a SEND request. Likewise, the active endpoint MUST immediately issue a SEND request.
This initial SEND request MAY have a empty body, or MAY carry This initial SEND request MAY have a body if the sender has content
content. to send, or it MAY have no body at all.
The first SEND request servers to bind a connection to an MSRP
session from the perspective of the passive endpoint. If the
connection is not authenticated with TLS, and the active endpoint
did not send an immediate request, the passive endpoint would have
no way to determine who had connected, and would not be able to
safely send any requests towards the active party until after the
active party sends its first request.
When an element needs to form a new connection, it looks at the URL When an element needs to form a new connection, it looks at the URL
to decide on the type of connection (TLS, TCP, etc.) then connects to to decide on the type of connection (TLS, TCP, etc.) then connects to
the host indicated by the URL, following the URL resolution rules in the host indicated by the URL, following the URL resolution rules in
Section 6.2. Connections using the msrps: scheme MUST use TLS. The Section 6.2. Connections using the msrps: scheme MUST use TLS. The
SubjectAltName in the received certificate MUST match the hostname SubjectAltName in the received certificate MUST match the hostname
part of the URL and the certificate MUST be valid, including having a part of the URL and the certificate MUST be valid, including having a
date that is valid and being signed by an acceptable certificate date that is valid and being signed by an acceptable certificate
authority. At this point the device that initiated the connection authority. At this point the device that initiated the connection
can assume that this connection is with the correct host. can assume that this connection is with the correct host.
If the connection used mutual TLS authentication, and the TLS client If the connection used mutual TLS authentication, and the TLS client
presented a valid certificate, then the element accepting the presented a valid certificate, then the element accepting the
connection can immediately know the identity of the connecting host. connection can immediately know the identity of the connecting host.
When mutual TLS authentication is not used, the listening device MUST When mutual TLS authentication is not used, the listening device MUST
wait until it receives a request on the connection, at which it wait until it receives a request on the connection, at which time it
infers the identity of the connecting device from the associated infers the identity of the connecting device from the associated
session description. session description.
When the first request arrives, its To-Path header field should When the first request arrives, its To-Path header field should
contain a URL that the listening element handed out in the SDP for a contain a URL that the listening element handed out in the SDP for a
session. The element that accepted the connection looks up the URL session. The element that accepted the connection looks up the URL
in the received request, and determines which session it matches. If in the received request, and determines which session it matches. If
a match exists, the node MUST assume that the host that formed the a match exists, the node MUST assume that the host that formed the
connection is the host to which this URL was given. If no match connection is the host to which this URL was given. If no match
exists, the node MUST reject the request with a 481 response. The exists, the node MUST reject the request with a 481 response. The
skipping to change at page 12, line 15 skipping to change at page 13, line 20
reject the request with a 506 response. reject the request with a 506 response.
If it were legal to have multiple connections associated with the If it were legal to have multiple connections associated with the
same session, a security problem would exist. If the initial SEND same session, a security problem would exist. If the initial SEND
request is not protected, an eavesdropper might learn the URL, and request is not protected, an eavesdropper might learn the URL, and
use it to insert messages into the session via a different use it to insert messages into the session via a different
connection. connection.
If a connection fails for any reason, then an MSRP endpoint MUST If a connection fails for any reason, then an MSRP endpoint MUST
consider any sessions associated with the connection as also having consider any sessions associated with the connection as also having
failed. When an endpoint notices such a failure, it MAY attempt to failed. When either endpoint notices such a failure, it MAY attempt
re-create any such sessions. If it chooses to do so, it MUST use new to re-create any such sessions. If it chooses to do so, it MUST use
SDP exchange, for example, in a SIP re-INVITE or UPDATE [11] request. a new SDP exchange, for example, in a SIP re-INVITE . If a
If a replacement session is successfully created, endpoints MAY replacement session is successfully created, endpoints MAY attempt to
attempt to resend any content for which delivery on the original resend any content for which delivery on the original session could
session could not be confirmed. If it does this, the Message-ID not be confirmed. If it does this, the Message-ID values for the
values for the resent messages MUST match those used in the initial resent messages MUST match those used in the initial attempts. If
attempts. If the receiving endpoint receives more than one message the receiving endpoint receives more than one message with the same
with the same Message-ID. It SHOULD assume that the messages are Message-ID. It SHOULD assume that the messages are duplicates. It
duplicates. It MAY take any action based on that knowledge, but MAY take any action based on that knowledge, but SHOULD NOT present
SHOULD NOT present the duplicate messages to the user without warning the duplicate messages to the user without warning of the
of the duplication. duplication. Note that acknowledgements as needed based on the
Failure-Report and Success-Report settings is still necessary even
for requests containing duplicate content.
In this situation, the endpoint MUST ensure that the Message-ID of In this situation, the endpoint MUST ensure that the Message-ID of
each distinct (i.e. non-duplicate) message is unique in the context each distinct (i.e. non-duplicate) message is unique in the context
of both the original session and the replacement session. of both the original session and the replacement session.
When endpoints create a new session in this fashion, the chunks for a When endpoints create a new session in this fashion, the chunks for a
given logical message MAY be split across the sessions. However, given logical message MAY be split across the sessions. However,
endpoints SHOULD NOT split chunks between sessions under non-failure endpoints SHOULD NOT split chunks between sessions under non-failure
circumstances. circumstances.
If an endpoint attempts to re-create a failed session in this manner, If an endpoint attempts to re-create a failed session in this manner,
it MUST NOT assume that the MSRP URLs in the SDP will be the same as it MUST NOT assume that the MSRP URLs in the SDP will be the same as
the old ones. the old ones.
A connection SHOULD not be closed while there are sessions associated A connection SHOULD NOT be closed while there are sessions associated
with it. with it.
6. MSRP URLs 6. MSRP URLs
URLs using the MSRP and MSRPS schema are used to identify a session URLs using the MSRP and MSRPS schema are used to identify a session
of instant messages at a particular MSRP device. MSRP URLs are of instant messages at a particular MSRP device. MSRP URLs are
ephemeral; an MSRP device will generally use a different MSRP URL for ephemeral; an MSRP device will generally use a different MSRP URL for
each distinct session. An MSRP URL generally has no meaning outside each distinct session. An MSRP URL generally has no meaning outside
of the associated session. of the associated session.
An MSRP URL follows a subset of the URL syntax in Appendix A of An MSRP URL follows a subset of the URL syntax in Appendix A of
RFC2396bis [9], with a scheme of "msrp" or "msrps". The syntax is RFC3986 [9], with a scheme of "msrp" or "msrps". The syntax is
described in Section 9. described in Section 9.
The constructions for "userinfo", and "unreserved" are detailed in The constructions for "userinfo", and "unreserved" are detailed in
RFC2396bis [9]. In order to allow IPV6 addressing, the construction RFC3986 [9]. In order to allow IPV6 addressing, the construction for
for hostport is that used for SIP in RFC3261. URLs designating MSRP hostport is that used for SIP in RFC3261. URLs designating MSRP over
over TCP MUST include the "tcp" transport parameter. TCP MUST include the "tcp" transport parameter.
Since this document only specifies MSRP over TCP, all MSRP URLs Since this document only specifies MSRP over TCP, all MSRP URLs
herein use the "tcp" transport parameter. Documents that provide herein use the "tcp" transport parameter. Documents that provide
bindings on other transports should define respective parameters bindings on other transports should define respective parameters
for those transports. for those transports.
An MSRP URL hostport field identifies a participant in a particular An MSRP URL hostport field identifies a participant in a particular
MSRP session. If the hostport contains a numeric IP address, it MUST MSRP session. If the hostport contains a numeric IP address, it MUST
also contain a port. The session-id part identifies a particular also contain a port. The session-id part identifies a particular
session of the participant. The absence of the session-id part session of the participant. The absence of the session-id part
indicates a reference to an MSRP host device, but does not indicates a reference to an MSRP host device, but does not
specifically refer to a particular session. specifically refer to a particular session.
A scheme of "msrps" indicates the underlying connection MUST be A scheme of "msrps" indicates the underlying connection MUST be
protected with TLS. protected with TLS.
MSRP has an IANA registered recommended port defined in Section 15.1. MSRP has an IANA registered recommended port defined in Section 15.4.
This value is not a default, as the URL negotiation process described This value is not a default, as the URL negotiation process described
herein will always include explicit port numbers. However, the URLs herein will always include explicit port numbers. However, the URLs
SHOULD be configured so that the recommended port is used whenever SHOULD be configured so that the recommended port is used whenever
appropriate. This makes life easier for network administrators who appropriate. This makes life easier for network administrators who
need to manage firewall policy for MSRP. need to manage firewall policy for MSRP.
The server part will typically not contain a userinfo component, but The hostport will typically not contain a userinfo component, but MAY
MAY do so to indicate a user account for which the session is valid. do so to indicate a user account for which the session is valid.
Note that this is not the same thing as identifying the session Note that this is not the same thing as identifying the session
itself. If a userinfo component exists, it MUST be constructed only itself. If a userinfo component exists, it MUST be constructed only
from "unreserved" characters, to avoid a need for escape processing. from "unreserved" characters, to avoid a need for escape processing.
Escaping MUST NOT be used in an MSRP URL. Furthermore, a userinfo Escaping MUST NOT be used in an MSRP URL. Furthermore, a userinfo
part MUST NOT contain password information. part MUST NOT contain password information.
The limitation of userinfo to unreserved characters is an The limitation of userinfo to unreserved characters is an
additional restriction to the userinfo definition in RFC2396bis. additional restriction to the userinfo definition in RFC3986.
That version allows reserved characters. The additional That version allows reserved characters. The additional
restriction is to avoid the need for escaping. restriction is to avoid the need for escaping.
The following is an example of a typical MSRP URL: The following is an example of a typical MSRP URL:
msrp://host.example.com:8493/asfd34;tcp msrp://host.example.com:8493/asfd34;tcp
6.1 MSRP URL Comparison 6.1 MSRP URL Comparison
MSRP URL comparisons MUST be performed according to the following MSRP URL comparisons MUST be performed according to the following
rules: rules:
1. The scheme must match. Scheme comparison is case insensitive. 1. The scheme must match. Scheme comparison is case insensitive.
2. If the hostpart contains an explicit IP address, and/or port, 2. If the hostpart contains an explicit IP address, and/or port,
these are compared for address and port equivalency. Otherwise, these are compared for address and port equivalence. Otherwise,
hostpart is compared as a case insensitive character string. hostpart is compared as a case insensitive character string.
3. If the port exists explicitly in either URL, then it must match 3. If the port exists explicitly in either URL, then it must match
exactly. An URL with an explicit port is never equivalent to exactly. A URL with an explicit port is never equivalent to
another with no port specified. another with no port specified.
4. The session-id part is compared as case sensitive. A URL without 4. The session-id part is compared as case sensitive. A URL without
a session-id part is never equivalent to one that includes one. a session-id part is never equivalent to one that includes one.
5. URLs with different "transport" parameters never match. Two URLs 5. URLs with different "transport" parameters never match. Two URLs
that are identical except for transport are not equivalent. The that are identical except for transport are not equivalent. The
transport parameter is case-insensitive. transport parameter is case-insensitive.
6. Userinfo parts are not considered for URL comparison. 6. Userinfo parts are not considered for URL comparison.
Path normalization is not relevant for MSRP URLs. Escape Path normalization is not relevant for MSRP URLs. Escape
normalization is not required due to character restrictions in the normalization is not required due to character restrictions in the
formal syntax. formal syntax.
6.2 Resolving MSRP Host Device 6.2 Resolving MSRP Host Device
An MSRP host device is identified by the server part of an MSRP URL. An MSRP host device is identified by the hostport of an MSRP URL.
If the server part contains a numeric IP address and port, they MUST If the hostport contains a numeric IP address and port, they MUST be
be used as listed. used as listed.
If the server part contains a host name and a port, the connecting If the hostport contains a host name and a port, the connecting
device MUST determine a host address by doing an A or AAAA DNS query, device MUST determine a host address by doing an A or AAAA DNS query,
and use the port as listed. and use the port as listed.
If a connection attempt fails, the device SHOULD attempt to connect If a connection attempt fails, the device SHOULD attempt to connect
to the addresses returned in any additional A or AAAA records, in the to the addresses returned in any additional A or AAAA records, in the
order the records were presented. order the records were presented.
This process assumes that the connection port is always known This process assumes that the connection port is always known
prior to resolution. This is always true for the MSRP URL uses prior to resolution. This is always true for the MSRP URL uses
described in this document, that is, URLs exchanged in the SDP described in this document, that is, URLs exchanged in the SDP
offer and answer. The introduction of relays may create offer and answer. The introduction of relays may create
situations where this is not the case. For example, the MSRP URL situations where this is not the case. For example, the MSRP URL
that a user enters into a client to configure it to use a relay that a user enters into a client to configure it to use a relay
may be intended to be easily remembered and communicated by may be intended to be easily remembered and communicated by
humans, and therefore is likely to omit the port. Therefore, the humans, and therefore is likely to omit the port. Therefore, the
relay specification [20] may describe additional steps to resolve relay specification [21] may describe additional steps to resolve
the port number. the port number.
MSRP devices MAY use other methods for discovering other such MSRP devices MAY use other methods for discovering other such
devices, when appropriate. For example, MSRP endpoints may use other devices, when appropriate. For example, MSRP endpoints may use other
mechanisms to discover relays, which are beyond the scope of this mechanisms to discover relays, which are beyond the scope of this
document. document.
7. Method-Specific Behavior 7. Method-Specific Behavior
7.1 Constructing Requests 7.1 Constructing Requests
To form a new request, the sender creates a unique transaction To form a new request, the sender creates a unique transaction
identifier and uses this and the method name to create an MSRP identifier and uses this and the method name to create an MSRP
request start line. Next, the sender places the target path in a request start line. Next, the sender places the target URL in a To-
To-Path header, and the sender's URL in a From-Path header. If Path header, and the sender's URL in a From-Path header. If multiple
multiple URLs are present in the To-Path, the leftmost is the first URLs are present in the To-Path, the leftmost is the first URL
URL visited; the rightmost URL is the last URL visited. The visited; the rightmost URL is the last URL visited. The processing
processing then becomes method specific. Additional method-specific then becomes method specific. Additional method-specific headers are
headers are added as described in the following sections. added as described in the following sections.
After any method-specific headers are added, processing continues to After any method-specific headers are added, processing continues to
handle a body, if present. A body in a Non-SEND request MUST NOT be handle a body, if present. A body in a non-SEND request MUST NOT be
longer than 2048 octets. If the request has a body, it must contain longer than 2048 octets. If the request has a body, it must contain
a Content-Type header field. It may contain other MIME specific a Content-Type header field. It may contain other MIME-specific
headers. The Content-Type header MUST be the last header line. The headers. The Content-Type header MUST be the last header line. The
body MUST be separated from the headers with an extra CRLF. Note body MUST be separated from the headers with an extra CRLF.
that, if no body is present, no blank line will be present between
the headers and the boundary marker below.
The boundary marker that terminates the body MUST be preceded by a A request with no body MUST NOT include a Content-Type header field.
CRLF that is not part of the body and then seven "-" (minus sign) Note that, if no body is present, no extra CRLF will be present
characters. After the boundary marker, there MUST be a flag between the headers and the end-line.
character. If the chunk represents the data that forms the end of
the complete message, the flag value MUST be a "$". If sender is
abandoning an incomplete message, and intends to send no further
chunks in that message, it MUST be a "#". Otherwise it MUST be a
"+".
If the request contains a body, the sender MUST ensure that the Requests with no bodies are useful when a client wishes to send
closing sequence (a CRLF, seven hyphens, and the transaction "traffic", but does not wish to send content to be rendered to the
identifier) is not present in the body. If the closing sequence is peer user. For example, the offerer must send a SEND request
present in the body, the sender MUST choose a new transaction immediately upon establishing a connection. If it has nothing to
identifier that is not present in the body, and add the closing say at the moment, it can send a request with no body. Bodiless
sequence, including the "$", "#", or "+" character, and a final CRLF. requests may also be used in certain applications to keep NAT
bindings alive, etc.
Bodiless requests are distinct from requests with empty bodies.
An request with an empty body will have a Content-Type header
value, and will generally be rendered to the recipient according
to the rules for that type.
The end-line that terminates the request MUST be composed of seven
"-" (minus sign) characters, the transaction ID as used in the start
line, and a flag character. If a body is present, the end-line must
be followed by a CRLF that is not part of the body. If the chunk
represents the data that forms the end of the complete message, the
flag value MUST be a "$". If sender is aborting an incomplete
message, and intends to send no further chunks in that message, it
MUST be a "#". Otherwise it MUST be a "+".
If the request contains a body, the sender MUST ensure that the end-
line (seven hyphens, the transaction identifier, and a continuation
flag) is not present in the body. If the end-line is present in the
body, the sender MUST choose a new transaction identifier that is not
present in the body, and add a CRLF if needed, and the end-line,
including the "$", "#", or "+" character.
Some implementations may choose to implement this such that if they Some implementations may choose to implement this such that if they
find the closing sequence in the body of the message they are find the closing sequence in the body of the message they are
sending, simply interrupting the message at that point and starting a sending, simply interrupting the message at that point and starting a
new transaction with a different transaction identifier to carry the new transaction with a different transaction identifier to carry the
rest of the body. Other implementation may choose to scan the data rest of the body. Other implementation may choose to scan the data
an ensure that the body does not contain the transaction identifier an ensure that the body does not contain the transaction identifier
before they start sending the transaction. before they start sending the transaction.
Finally, requests which have no body MUST NOT contain a Content-Type Finally, requests which have no body MUST NOT contain a Content-Type
header or any other MIME specific header. Requests without bodies header or any other MIME specific header. Requests without bodies
MUST contain a closing sequence after the final header. MUST contain a end-line after the final header.
Once a request is ready for delivery, the sender follows the Once a request is ready for delivery, the sender follows the
connection management (Section 5.4) rules to forward the request over connection management (Section 5.4) rules to forward the request over
an existing open connection or create a new connection. an existing open connection or create a new connection.
7.1.1 Delivering SEND requests 7.1.1 Sending SEND requests
When an endpoint has a message to deliver, it first generates a new When an endpoint has a message to deliver, it first generates a new
unique Message-ID. This ID MUST be unique within the scope of the unique Message-ID. This ID MUST be globally unique. If necessary,
session. If necessary, it breaks the message into chunks. It then it breaks the message into chunks. It then generates a SEND request
generates a SEND request for each chunk, following the procedures for for each chunk, following the procedures for constructing requests
constructing requests (Section 7.1). (Section 7.1).
Each chunk MUST contain a Message-ID header field containing the The Message-ID header field provides a unique message identifier
Message-ID. If the sender wishes non-default status reporting, it that refers to a particular version of a particular message. The
MUST insert a Failure-Report and/or Success-Report header field with term "Message" in this context refers to a unit of content that
an appropriate value. All chunks of the same message MUST use the the sender wishes to convey to the recipient. While such a
same Failure-Report and Success-Report values in their SEND requests. message may be broken into chunks, the Message-ID refers to the
entire message, not a chunk of the message.
The uniqueness of the message identifier is guaranteed by the host
that generates it. This message identifier is intended to be
machine readable and not necessarily meaningful to humans. A
message identifier pertains to exactly one version of a particular
message; subsequent revisions to the message each receive new
message identifiers.
If success reports are requested, i.e. the value of the Each chunk of a message MUST contain a Message-ID header field
Success-Report header is "yes", the sending device MAY wish to run a containing the Message-ID. If the sender wishes non-default status
timer of some value that makes sense for its application and take reporting, it MUST insert a Failure-Report and/or Success-Report
action if a success Report is not received in this time. There is no header field with an appropriate value. All chunks of the same
universal value for this timer. For many IM applications, it may be message MUST use the same Failure-Report and Success-Report values in
2 minutes while for some trading systems it may be under a second. their SEND requests.
Regardless of whether such a timer is used, if the success report has
not been received by the time the session is ended, the device SHOULD If success reports are requested, i.e. the value of the Success-
inform the user. Report header is "yes", the sending device MAY wish to run a timer of
some value that makes sense for its application and take action if a
success Report is not received in this time. There is no universal
value for this timer. For many IM applications, it may be 2 minutes
while for some trading systems it may be under a second. Regardless
of whether such a timer is used, if the success report has not been
received by the time the session is ended, the device SHOULD inform
the user.
If the value of "Failure-Report" is set to "yes", then the sender of If the value of "Failure-Report" is set to "yes", then the sender of
the request runs a timer. If a 200 response to the transaction is the request runs a timer. If a 200 response to the transaction is
not received within 30 seconds from the time the last byte of the not received within 30 seconds from the time the last byte of the
transaction is sent, the element MUST inform the user that the transaction is sent, or submitted to the operating system for
request probably failed. If the value is set to "partial", then the sending, the element MUST inform the user that the request probably
element sending the transaction does not have to run a timer, but failed. If the value is set to "partial", then the element sending
MUST inform the user if receives a non-recoverable error response to the transaction does not have to run a timer, but MUST inform the
the transaction. user if it receives a non-recoverable error response to the
transaction.
If no Success-Report header is present in a SEND request, it MUST be If no Success-Report header is present in a SEND request, it MUST be
treated the same as a Success-Report header with value of "no". If treated the same as a Success-Report header with value of "no". If
no Failure-Report header is present, it MUST be treated the same as a no Failure-Report header is present, it MUST be treated the same as a
Failure-Report header with value of "yes". REPORT requests MUST have Failure-Report header with value of "yes". If an MSRP endpoint
the same Message-ID header value as the request they are reporting receives a REPORT for a Message-ID it does not recognize, it SHOULD
on. They MAY also have the Byte-Range of the chunk they are silently ignore the REPORT.
reporting on. If an MSRP endpoint receives a REPORT for a Message-ID
it does not recognize, it SHOULD silently ignore the REPORT.
Success-Report and Failure-Report MUST NOT be present for any method Success-Report and Failure-Report MUST NOT be present in REPORT
other than SEND. MSRP nodes MUST NOT send REPORT requests in requests. MSRP nodes MUST NOT send REPORT requests in response to
response to report requests. MSRP Nodes MUST NOT send MSRP responses report requests. MSRP Nodes MUST NOT send MSRP responses to REPORT
to REPORT requests. requests.
The Byte-Range header value contains a starting value (range-start) The Byte-Range header value contains a starting value (range-start)
followed by a "-", an ending value (range-end) followed by a "/", and followed by a "-", an ending value (range-end) followed by a "/", and
finally the total length. The first octet in the message has a finally the total length. The first octet in the message has a
position of one, rather than a zero. position of one, rather than a zero.
The first chunk of the message SHOULD, and all subsequent chunks MUST The first chunk of the message SHOULD, and all subsequent chunks MUST
include a Byte-Range header field. The range-start field MUST include a Byte-Range header field. The range-start field MUST
indicate the position of the first byte in the body in the overall indicate the position of the first byte in the body in the overall
message (for the first chunk this field will have a value of one). message (for the first chunk this field will have a value of one).
skipping to change at page 18, line 8 skipping to change at page 19, line 46
send chunks in 2048 octet increments until the final chunk. Note send chunks in 2048 octet increments until the final chunk. Note
that the former strategy results in markedly more efficient use of that the former strategy results in markedly more efficient use of
the connection. All MSRP nodes MUST be able to receive chunks of any the connection. All MSRP nodes MUST be able to receive chunks of any
size from zero octets to the maximum number of octets they can size from zero octets to the maximum number of octets they can
receive for a complete message. Senders SHOULD NOT break messages receive for a complete message. Senders SHOULD NOT break messages
into chunks smaller than 2048 octets, except for the final chunk of a into chunks smaller than 2048 octets, except for the final chunk of a
complete message. complete message.
A SEND request is interrupted while a body is in the process of being A SEND request is interrupted while a body is in the process of being
written to the connection by simply noting how much of the message written to the connection by simply noting how much of the message
has already been written to the connection, then writing out the has already been written to the connection, then writing out the end-
boundary string to end the chunk. It can then be resumed in a line to end the chunk. It can then be resumed in a another chunk
another chunk with the same Message-ID and a Byte-Range header range with the same Message-ID and a Byte-Range header range start field
start field containing the position of the first byte after the containing the position of the first byte after the interruption
interruption occurred. occurred.
SEND requests larger than 2048 octets MUST be interrupted to send SEND requests larger than 2048 octets MUST be interrupted if the
pending responses or REPORT requests. If multiple SEND requests from sender needs to send pending responses or REPORT requests. If
different sessions are concurrently being sent over the same multiple SEND requests from different sessions are concurrently being
connection, the device SHOULD implement some scheme to alternate sent over the same connection, the device SHOULD implement some
between them such that each concurrent request gets a chance to send scheme to alternate between them such that each concurrent request
some fair portion of data at regular intervals suitable to the gets a chance to send some fair portion of data at regular intervals
application. suitable to the application.
The sender MUST NOT assume that a message is received by the peer The sender MUST NOT assume that a message is received by the peer
with the same chunk allocation with which it was sent. An with the same chunk allocation with which it was sent. An
intervening relay could possibly break SEND requests into smaller intervening relay could possibly break SEND requests into smaller
chunks, or aggregate multiple chunks into larger ones. chunks, or aggregate multiple chunks into larger ones.
The default disposition of bodies is "render". If the sender wants The default disposition of bodies is "render". If the sender wants
different disposition, it MAY insert a Content-Disposition header. different disposition, it MAY insert a Content-Disposition header.
Since MSRP is a binary protocol, transfer encoding is always Since MSRP is a binary protocol, transfer encoding is always
"binary", and transfer-encoding paramaters MUST NOT be present. "binary", and transfer-encoding parameters MUST NOT be present.
7.1.2 Sending REPORT requests 7.1.2 Sending REPORT requests
REPORT requests are similar to SEND requests, except that report REPORT requests are similar to SEND requests, except that report
requests MUST NOT include Success-Report or Failure-Report header requests MUST NOT include Success-Report or Failure-Report header
fields, and MUST contain a Status header field. REPORT requests MUST fields, and MUST contain a Status header field. REPORT requests MUST
contain the Message-ID header from the original SEND request. contain the Message-ID header from the original SEND request.
If an MSRP element receives a REPORT for a Message-ID it does not If an MSRP element receives a REPORT for a Message-ID it does not
recognize, it SHOULD silently ignore the REPORT. recognize, it SHOULD silently ignore the REPORT.
skipping to change at page 19, line 15 skipping to change at page 21, line 5
An endpoint MUST send a success report if it successfully receives a An endpoint MUST send a success report if it successfully receives a
SEND request which contained a Success-Report value of "yes" and SEND request which contained a Success-Report value of "yes" and
either contains a complete message, or contains the last chunk needed either contains a complete message, or contains the last chunk needed
to complete the message. This request is sent following the normal to complete the message. This request is sent following the normal
procedures (Section 7.1), with a few additional requirements. procedures (Section 7.1), with a few additional requirements.
The endpoint inserts a To-Path header field containing the From-Path The endpoint inserts a To-Path header field containing the From-Path
value from the original request, and a From-Path header containing value from the original request, and a From-Path header containing
the URL identifying itself in the session. The endpoint then inserts the URL identifying itself in the session. The endpoint then inserts
a Status header field with a namespace of "000", a short-status of a Status header field with a namespace of "000", a short-status of
"200" and a relevant Reason phrase, and a Message-ID header field "200" and an implementation defined comment phrase. It also inserts
containing the value from the original request. a Message-ID header field containing the value from the original
request.
The namespace field denotes the context the short-status field. The namespace field denotes the context of the short-status field.
The namespace value of "000" means the short-status should be The namespace value of "000" means the short-status should be
interpreted in the same way as the matching MSRP transaction interpreted in the same way as the matching MSRP transaction
response code. If a future specification uses the short-status response code. If a future specification uses the short-status
field for some other purpose, it MUST define a new namespace field field for some other purpose, it MUST define a new namespace field
value. value.
The endpoint MUST NOT send a success report for a SEND request that The endpoint MUST NOT send a success report for a SEND request that
either contained no Success-Report header field, or contained such a either contained no Success-Report header field, or contained such a
field with a value of "no". That is, if no Success-Report header field with a value of "no". That is, if no Success-Report header
field is present, it is treated identically to one with a value of field is present, it is treated identically to one with a value of
skipping to change at page 20, line 29 skipping to change at page 22, line 20
This section only describes failure report generation behavior for This section only describes failure report generation behavior for
MSRP endpoints. Relay behavior is beyond the scope of this MSRP endpoints. Relay behavior is beyond the scope of this
document, and will be considered in a separate document. We document, and will be considered in a separate document. We
expect failure reports to be more commonly generated by relays expect failure reports to be more commonly generated by relays
than by endpoints. than by endpoints.
7.2 Constructing Responses 7.2 Constructing Responses
If an MSRP endpoint receives a request that either contains a If an MSRP endpoint receives a request that either contains a
Failure-Report header value of "yes", or does not contain a Failure-Report header value of "yes", or does not contain a Failure-
Failure-Report header field at all, it MUST immediately generate a Report header field at all, it MUST immediately generate a response.
response. Likewise, if an MSRP endpoint receives a request that Likewise, if an MSRP endpoint receives a request that contains a
contains a Failure-Report header value of "partial", and the receiver Failure-Report header value of "partial", and the receiver is unable
is unable to process the request, it SHOULD immediately generate a to process the request, it SHOULD immediately generate a response.
response.
To construct the response, the endpoint first creates the response To construct the response, the endpoint first creates the response
start-line, inserting appropriate response code and reason fields. start-line, inserting appropriate response code and reason fields.
The transaction identifier in the response start line MUST match the The transaction identifier in the response start line MUST match the
transaction identifier from the original request. transaction identifier from the original request.
The endpoint then inserts an appropriate To-Path header field. If The endpoint then inserts an appropriate To-Path header field. If
the request triggering the response was a SEND request, the To-Path the request triggering the response was a SEND request, the To-Path
header field is formed by copying the last (right-most) URL in the header field is formed by copying the last (right-most) URL in the
From-Path header field of the request. (Responses to SEND requests From-Path header field of the request. (Responses to SEND requests
skipping to change at page 21, line 8 skipping to change at page 22, line 47
to the original sender. This full path is generated by taking the to the original sender. This full path is generated by taking the
list of URLs from the From-Path of the original request, reversing list of URLs from the From-Path of the original request, reversing
the list, and writing the reversed list into the To-Path of the the list, and writing the reversed list into the To-Path of the
response. (Legal REPORT requests do not request responses, so this response. (Legal REPORT requests do not request responses, so this
specification doesn't exercise the behavior described above, however specification doesn't exercise the behavior described above, however
we expect that extensions for gateways and relays will need such we expect that extensions for gateways and relays will need such
behavior.) behavior.)
Finally, the endpoint inserts a From-Path header field containing the Finally, the endpoint inserts a From-Path header field containing the
URL that identifies it in the context of the session, followed by the URL that identifies it in the context of the session, followed by the
closing sequence after the last header field. The response MUST be end-line after the last header field. The response MUST be
transmitted back on the same connection on which the original request transmitted back on the same connection on which the original request
arrived. arrived.
7.3 Receiving Requests 7.3 Receiving Requests
The receiving endpoint must first check the URL in the To-Path to The receiving endpoint must first check the URL in the To-Path to
make sure the request belongs to an existing session. When the make sure the request belongs to an existing session. When the
request is received, the To-Path will have exactly one URL, which request is received, the To-Path will have exactly one URL, which
MUST map to an existing session that is associated with the MUST map to an existing session that is associated with the
connection on which the request arrived. If this is not true then connection on which the request arrived. If this is not true then
the receiver MUST generate an 481 error and ignore the request. Note the receiver MUST generate a 481 error and ignore the request. Note
that if the Failure-Report header had a value of "no", then no error that if the Failure-Report header had a value of "no", then no error
report would be sent. report would be sent.
Further request processing by the receiver is method specific. Further request processing by the receiver is method specific.
7.3.1 Receiving SEND requests 7.3.1 Receiving SEND requests
When the receiving endpoint receives a SEND request, it first When the receiving endpoint receives a SEND request, it first
determines if it contains a complete message, or a chunk from a determines if it contains a complete message, or a chunk from a
larger message. If the request contains no Byte-Range header, or larger message. If the request contains no Byte-Range header, or
skipping to change at page 21, line 45 skipping to change at page 23, line 38
bytes have been received and which are missing. The receiver takes bytes have been received and which are missing. The receiver takes
the data from the request and places it in the appropriate place in the data from the request and places it in the appropriate place in
the buffer. The receiver SHOULD determine the actual length of each the buffer. The receiver SHOULD determine the actual length of each
chunk by inspecting the payload itself; it is possible the body is chunk by inspecting the payload itself; it is possible the body is
shorter than the range-end field indicates. This can occur if the shorter than the range-end field indicates. This can occur if the
sender interrupted a SEND request unexpectedly. It is worth nothing sender interrupted a SEND request unexpectedly. It is worth nothing
that the chunk that has a termination character of "$" defines the that the chunk that has a termination character of "$" defines the
total length of the message. total length of the message.
It is technically illegal for the sender to prematurely interrupt It is technically illegal for the sender to prematurely interrupt
a request that had anything other "*" in the last-byte position of a request that had anything other than "*" in the last-byte
the Byte-Range header. But having the receiver calculate a chunk position of the Byte-Range header. But having the receiver
length based on actual content adds resilience in the face of calculate a chunk length based on actual content adds resilience
sender errors. Since this should never happen with compliant in the face of sender errors. Since this should never happen with
senders, this only has a SHOULD strength. compliant senders, this only has a SHOULD strength.
Receivers MUST not assume the chunks will be delivered in order or Receivers MUST not assume the chunks will be delivered in order or
that they will receive all the chunks with "+" flags before they that they will receive all the chunks with "+" flags before they
receive the chunk with the "$" flag. In certain cases of connection receive the chunk with the "$" flag. In certain cases of connection
failure, it is possible for information to be duplicated. If chunk failure, it is possible for information to be duplicated. If chunk
data is received that overlaps already received data for the same data is received that overlaps already received data for the same
message, the last chunk received takes precedence (even though this message, the last chunk received SHOULD take precedence (even though
may not have been the last chunk transmitted). For example, if bytes this may not have been the last chunk transmitted). For example, if
1 to 100 was received and a chunk arrives that contains bytes 50 to bytes 1 to 100 were received and a chunk arrives that contains bytes
150, this second chunk will overwrite bytes 50 to 100 of the data 50 to 150, this second chunk will overwrite bytes 50 to 100 of the
that had already been received. Although other schemes work, this is data that had already been received. Although other schemes work,
the easiest for the receiver and results in consistent behavior this is the easiest for the receiver and results in consistent
between clients. behavior between clients.
The seven "-" before the boundary are used so that the receiver can There are situations in which the receiver may not be able to give
precedent to the last chunk received when chunks overlap. For
example, the recipient might incrementally render chunks as they
arrive. If a new chunk arrives that overlaps with a previously
rendered chunk, it would be to late to "take back" any conflicting
data from the first chunk. Therefore, the requirement to give
precedent to the most recent chunk is specified at a "SHOULD"
strength. This requirement is not intended to disallow
applications where it does not make sense.
The seven "-" in the end-line are used so that the receiver can
search for the value "----", 32 bits at a time to find the probable search for the value "----", 32 bits at a time to find the probable
location of the boundary. This allows most processors to locate the location of the end-line. This allows most processors to locate the
boundaries and copy the memory at the same rate that a normal memory boundaries and copy the memory at the same rate that a normal memory
copy could be done. This approach results in a system that is as copy could be done. This approach results in a system that is as
fast as framing based on specifying the body length in the headers of fast as framing based on specifying the body length in the headers of
the request, but also allows for the interruption of messages. the request, but also allows for the interruption of messages.
What is done with the body is outside the scope of MSRP and largely What is done with the body is outside the scope of MSRP and largely
determined by the MIME Content-Type and Content-Disposition. The determined by the MIME Content-Type and Content-Disposition. The
body MAY be rendered after the whole message is received or partially body MAY be rendered after the whole message is received or partially
rendered as it is being received. rendered as it is being received.
If the SEND request contained a Content-Type header field indicating If the SEND request contained a Content-Type header field indicating
an unsupported MIME type, the receiver MUST generate a failure report an unsupported MIME type, and the Failure-Report value is not "no",
with a 415 error code. Note that this failure report will not be the receiver MUST generate a response with a status code of 415. All
sent if the Report-Failure header contains a value of "no". All MSRP MSRP endpoints MUST be able to receive the multipart/mixed [15] and
endpoints MUST be able to receive the multipart/mixed and multipart/alternative [15] MIME types.
multipart/alternative MIME types.
If the Success-Report header was set to "yes", then when a complete If the Success-Report header was set to "yes", then when a complete
message has been received, the receiver MUST send a success REPORT message has been received, the receiver MUST send a success REPORT
with a byte range covering the whole message. If the Success-Report with a byte range covering the whole message. If the Success-Report
header is not set to "no", then the receiver MAY generate incremental header is set to "yes", then the receiver MAY generate incremental
success REPORTs as the chunks are received. These can be sent success REPORTs as the chunks are received. These can be sent
periodically and cover all the bytes that have been received so far periodically and cover all the bytes that have been received so far
or they can be sent after a chunk arrives and cover just the part or they can be sent after a chunk arrives and cover just the part
from that chunk. from that chunk.
It is helpful to think of a success REPORT as reporting on a
particular range of bytes, rather than on a particular chunk sent
by a client. The sending client cannot depend on the Byte-Range
header field in a given success report matching the that of a
particular SEND request. For example, an intervening MSRP relay
may break chunks into smaller chunks, or aggregate multiple chunks
into larger ones.
A side effect of this is, even if no relay is used, the receiving
client may report on byte ranges that do not exactly match those
in the original chunks sent by the sender. It can wait until all
bytes in a message are received and report on the whole, it can
report as it receives each chunk, or it can report on any other
received range.
Reporting on ranges smaller than the entire message contents
allows certain improved user experiences for the sender. For
example, a sending client could display incremental status
information showing which ranges of bytes have been acknowledged
by the receiver.
However, the choice on whether to report incrementally is entirely
up to the receiving client. There is no mechanism for the sender
to assert its desire to receive incremental reports or not. Since
the presence of a relay can cause the receiver to see a very
different chunk allocation than the sender, such a mechanism would
be of questionable value.
7.3.2 Receiving REPORT requests 7.3.2 Receiving REPORT requests
When an endpoint receives a REPORT request, it correlates it to the When an endpoint receives a REPORT request, it correlates it to the
original SEND request using the Message-ID and the Byte-Range, if original SEND request using the Message-ID; and the Byte-Range, if
present. If it requested success reports, then it SHOULD keep enough present. If it requested success reports, then it SHOULD keep enough
state about each outstanding sent message so that it can correlate state about each outstanding sent message so that it can correlate
REPORT requests to the original messages. REPORT requests to the original messages.
An endpoint that receives a REPORT request containing a Status header An endpoint that receives a REPORT request containing a Status header
with a namespace field of "000", MUST interpret the report in exactly with a namespace field of "000", MUST interpret the report in exactly
the same way it would interpret an MSRP transaction response with a the same way it would interpret an MSRP transaction response with a
response code matching the short-code field. response code matching the short-code field.
It is possible to receive a failure report or a failure transaction It is possible to receive a failure report or a failure transaction
response for a chunk that is currently being delivered. In this case response for a chunk that is currently being delivered. In this case
the entire message corresponding to that chunk should be aborted, by the entire message corresponding to that chunk should be aborted, by
including the "#" character in the continuation field of the closing including the "#" character in the continuation field of the end-
sequence. line.
It is possible that an endpoint will receive a REPORT request on a It is possible that an endpoint will receive a REPORT request on a
session that is no longer valid. The endpoint's behavior if this session that is no longer valid. The endpoint's behavior if this
happens is a matter of local policy. The endpoint is not required to happens is a matter of local policy. The endpoint is not required to
take any steps to facilitate such late delivery, i.e. it is not take any steps to facilitate such late delivery, i.e. it is not
expected to keep a connection active in case late REPORTs might expected to keep a connection active in case late REPORTs might
arrive. arrive.
When a device that sent a SEND request receives a failure REPORT When and endpoint that sent a SEND request receives a failure REPORT
indicating that a particular byte range was not received, it MUST indicating that a particular byte range was not received, it MUST
treat the session as failed. If it wishes to recover, it MUST first treat the session as failed. If it wishes to recover, it MUST first
re-negotiate the URLs at the signaling level then resend that range re-negotiate the URLs at the signaling level then resend that range
of bytes of the message on the resulting new session. of bytes of the message on the resulting new session.
MSRP Modes MUST NOT send a MSRP REPORT in responses to REPORT MSRP nodes MUST NOT send MSRP REPORT requests in responses to other
requests. REPORT requests.
8. Using MSRP with SIP 8. Using MSRP with SIP
8.1 SDP Offer-Answer Exchanges for MSRP Sessions 8.1 SDP Offer-Answer Exchanges for MSRP Sessions
MSRP sessions will typically be initiated using the Session MSRP sessions will typically be initiated using the Session
Description Protocol (SDP) [2] via the SIP offer-answer mechanism Description Protocol (SDP) [2] via the SIP offer-answer mechanism
[3]. [3].
This document defines a handful of new SDP parameters to setup MSRP This document defines a handful of new SDP parameters to setup MSRP
skipping to change at page 24, line 36 skipping to change at page 27, line 15
Occasionally an endpoint will need to specify a MIME body type that Occasionally an endpoint will need to specify a MIME body type that
can only be used if wrapped inside a listed container type. can only be used if wrapped inside a listed container type.
Endpoints MAY specify MIME types that are only allowed when wrapped Endpoints MAY specify MIME types that are only allowed when wrapped
inside compound types using the "accept-wrapped-types" attribute in inside compound types using the "accept-wrapped-types" attribute in
an SDP a-line. an SDP a-line.
The semantics for accept-wrapped-types are identical to those of the The semantics for accept-wrapped-types are identical to those of the
accept-types attribute, with the exception that the specified types accept-types attribute, with the exception that the specified types
may only be used when wrapped inside containers. Only types listed may only be used when wrapped inside container types listed in
in the accept-types attribute may be used as the "root" type for the accept-types attribute. Only types listed in the accept-types
entire body. Since any type listed in accept-types may be used both attribute may be used as the "root" type for the entire body. Since
as a root body, and wrapped in other bodies, format entries from any type listed in accept-types may be used both as a root body, and
accept-types SHOULD NOT be repeated in this attribute. wrapped in other bodies, format entries from accept-types SHOULD NOT
be repeated in this attribute.
This approach does not allow for specifying distinct lists of This approach does not allow for specifying distinct lists of
acceptable wrapped types for different types of containers. If an acceptable wrapped types for different types of containers. If an
endpoint understands a MIME type in the context of one wrapper, it is endpoint understands a MIME type in the context of one wrapper, it is
assumed to understand it in the context of any other acceptable assumed to understand it in the context of any other acceptable
wrappers, subject to any constraints defined by the wrapper types wrappers, subject to any constraints defined by the wrapper types
themselves. themselves.
The approach of specifying types that are only allowed inside of The approach of specifying types that are only allowed inside of
containers separately from the primary payload types allows an containers separately from the primary payload types allows an
skipping to change at page 26, line 18 skipping to change at page 29, line 4
the path value received from the peer, and uses that value as the the path value received from the peer, and uses that value as the
target for requests inside the resulting session. If the path target for requests inside the resulting session. If the path
attribute received from the peer contains more than one URL, then the attribute received from the peer contains more than one URL, then the
target URL is the rightmost, while the leftmost entry represents the target URL is the rightmost, while the leftmost entry represents the
adjacent hop. If only one entry is present, then it is both the peer adjacent hop. If only one entry is present, then it is both the peer
and adjacent hop URL. The target path is the entire path attribute and adjacent hop URL. The target path is the entire path attribute
value received from the peer. value received from the peer.
The following example shows an SDP offer with a session URL of The following example shows an SDP offer with a session URL of
"msrp://alice.example.com:7394/2s93i;tcp" "msrp://alice.example.com:7394/2s93i;tcp"
v=0 v=0
o=alice 2890844526 2890844527 IN IP4 alice.example.com o=alice 2890844526 2890844527 IN IP4 alice.example.com
s= s=
c=IN IP4 alice.example.com c=IN IP4 alice.example.com
m=message 7394 msrp/tcp * m=message 7394 TCP/MSRP *
a=accept-types:text/plain a=accept-types:text/plain
a=path:msrp://alice.example.com:7394/2s93i;tcp a=path:msrp://alice.example.com:7394/2s93i;tcp
The rightmost URL in the path attribute MUST identify the endpoint The rightmost URL in the path attribute MUST identify the endpoint
that generated the SDP document, or some other location where that that generated the SDP document, or some other location where that
endpoint wishes to receive requests associated with the session. It endpoint wishes to receive requests associated with the session. It
MUST be assigned for this particular session, and MUST NOT duplicate MUST be assigned for this particular session, and MUST NOT duplicate
any URL in use for any other session in which the endpoint is any URL in use for any other session in which the endpoint is
currently participating. It SHOULD be hard to guess, and protected currently participating. It SHOULD be hard to guess, and protected
from eavesdroppers. This is discussed in more detail in Section 14. from eavesdroppers. This is discussed in more detail in Section 14.
8.1.2 Path Attributes with Multiple URLs 8.1.2 Path Attributes with Multiple URLs
As mentioned previously, this document describes MSRP for As mentioned previously, this document describes MSRP for peer-to-
peer-to-peer scenarios, that is, when no relays are used. However, peer scenarios, that is, when no relays are used. However, we expect
we expect a separate document to describe the use of relays. In a separate document to describe the use of relays. In order to allow
order to allow an MSRP device that only implements the core an MSRP device that only implements the core specification to
specification to interoperate with devices that use relays, this interoperate with devices that use relays, this document must include
document must include a few assumptions about how relays work. a few assumptions about how relays work.
An endpoint that uses one or more relays will indicate that by An endpoint that uses one or more relays will indicate that by
putting a URL for each device in the relay chain into the SDP path putting a URL for each device in the relay chain into the SDP path
attribute. The final entry would point to the endpoint itself. The attribute. The final entry would point to the endpoint itself. The
other entries would indicate each proposed relay, in order. The other entries would indicate each proposed relay, in order. The
first entry would point to the first relay in the chain from the first entry would point to the first relay in the chain from the
perspective of the peer; that is, the relay to which the peer device, perspective of the peer; that is, the relay to which the peer device,
or a relay operating on its behalf, should connect. or a relay operating on its behalf, should connect.
Endpoints that do not wish to insert a relay, including those that do Endpoints that do not wish to insert a relay, including those that do
skipping to change at page 27, line 32 skipping to change at page 30, line 16
entries in the attribute are out of scope for this document. entries in the attribute are out of scope for this document.
8.1.3 SDP Connection and Media Lines 8.1.3 SDP Connection and Media Lines
The format of an SDP connection-line takes the following format: The format of an SDP connection-line takes the following format:
c=<network type> <address type> <connection address> c=<network type> <address type> <connection address>
The network type and address type fields are used as normal for SDP. The network type and address type fields are used as normal for SDP.
The connection address field MUST be set to the IP address or fully The connection address field MUST be set to the IP address or fully
qualified domain name from MSRP URL identifying the endpoint in its qualified domain name from the MSRP URL identifying the endpoint in
PATH attribute. its PATH attribute.
The general format of an SDP media-line is: The general format of an SDP media-line is:
m=<media> <port> <protocol> <format list> m=<media> <port> <protocol> <format list>
An offered or accepted media-line for MSRP over TCP MUST include a An offered or accepted media-line for MSRP over TCP MUST include a
protocol field value of "msrp/tcp". The media field value MUST be protocol field value of "TCP/MSRP", or "TCP/TLS/MSRP" for TLS. The
"message". The format list field MUST be set to "*". media field value MUST be "message". The format list field MUST be
set to "*".
The port field value MUST match the port value used in the endpoint's The port field value MUST match the port value used in the endpoint's
MSRP URL in the PATH attribute, except that, as described in [3], a MSRP URL in the PATH attribute, except that, as described in [3], a
user agent that wishes to accept an offer, but not a specific user agent that wishes to accept an offer, but not a specific media-
media-line MUST set the port number of that media-line to zero (0) in line MUST set the port number of that media-line to zero (0) in the
the response.) Since MSRP allows multiple sessions to share the same response.) Since MSRP allows multiple sessions to share the same TCP
TCP connection, multiple m-lines in a single SDP document may share connection, multiple m-lines in a single SDP document may share the
the same port field value; MSRP devices MUST NOT assume any same port field value; MSRP devices MUST NOT assume any particular
particular relationship between m-lines on the sole basis that they relationship between m-lines on the sole basis that they have
have matching port field values. matching port field values.
MSRP devices do not use the c-line address field, or the m-line MSRP devices do not use the c-line address field, or the m-line
port and format list fields to determine where to connect. port and format list fields to determine where to connect.
Rather, they use the attributes defined in this specification. Rather, they use the attributes defined in this specification.
The connection information is copied to the c-line and m-line for The connection information is copied to the c-line and m-line for
purposes of backwards compatibility with conventional SDP usages. purposes of backwards compatibility with conventional SDP usages.
While MSRP could theoretically carry any media type, "message" is While MSRP could theoretically carry any media type, "message" is
appropriate. appropriate.
8.1.4 Updated SDP Offers 8.1.4 Updated SDP Offers
skipping to change at page 28, line 36 skipping to change at page 31, line 21
exchange. This new path may be the same as its previous path, but exchange. This new path may be the same as its previous path, but
may be different. The new offerer MUST NOT assume that the peer will may be different. The new offerer MUST NOT assume that the peer will
answer with the same path it used previously. answer with the same path it used previously.
If either party wishes to send an SDP document that changes nothing If either party wishes to send an SDP document that changes nothing
at all, then it MUST have the same o-line as in the previous at all, then it MUST have the same o-line as in the previous
exchange. exchange.
8.1.5 Example SDP Exchange 8.1.5 Example SDP Exchange
Endpoint A wishes to invite Endpoint B to a MSRP session. A offers Endpoint A wishes to invite Endpoint B to an MSRP session. A offers
the following session description: the following session description:
v=0 v=0
o=usera 2890844526 2890844527 IN IP4 alice.example.com o=usera 2890844526 2890844527 IN IP4 alice.example.com
s= s=
c=IN IP4 alice.example.com c=IN IP4 alice.example.com
t=0 0 t=0 0
m=message 7394 msrp/tcp * m=message 7394 TCP/MSRP *
a=accept-types: message/cpim text/plain text/html a=accept-types: message/cpim text/plain text/html
a=path:msrp://alice.example.com:7394/2s93i9;tcp a=path:msrp://alice.example.com:7394/2s93i9;tcp
B responds with its own URL: B responds with its own URL:
v=0 v=0
o=userb 2890844530 2890844532 IN IP4 bob.example.com o=userb 2890844530 2890844532 IN IP4 bob.example.com
s= s=
c=IN IP4 bob.example.com c=IN IP4 bob.example.com
t=0 0 t=0 0
m=message 8493 msrp/tcp * m=message 8493 TCP/MSRP *
a=accept-types:message/cpim text/plain a=accept-types:message/cpim text/plain
a=path:msrp://bob.example.com:8493/si438ds;tcp a=path:msrp://bob.example.com:8493/si438ds;tcp
8.1.6 Connection Negotiation 8.1.6 Connection Negotiation
Previous versions of this document included a mechanism to negotiate Previous versions of this document included a mechanism to negotiate
the direction for any required TCP connection. The mechanism was the direction for any required TCP connection. The mechanism was
loosely based on the COMEDIA [23] work being done in the MMUSIC loosely based on the COMEDIA [24] work being done in the MMUSIC
working group. The primary motivation was to allow MSRP sessions to working group. The primary motivation was to allow MSRP sessions to
succeed in situations where the offerer could not accept connections succeed in situations where the offerer could not accept connections
but the answerer could. For example, the offerer might be behind a but the answerer could. For example, the offerer might be behind a
NAT, while the answerer might have a globally routable address. NAT, while the answerer might have a globally routable address.
The SIMPLE working group chose to remove that mechanism from MSRP, as The SIMPLE working group chose to remove that mechanism from MSRP, as
it added a great deal of complexity to connection management. it added a great deal of complexity to connection management.
Instead, MSRP now specifies a default connection direction. Namely, Instead, MSRP now specifies a default connection direction. Namely,
the party that sent the original offer the party that sent the original offer.
8.2 MSRP User Experience with SIP 8.2 MSRP User Experience with SIP
In typical SIP applications, when an endpoint receives an INVITE In typical SIP applications, when an endpoint receives an INVITE
request, it alerts the user, and waits for user input before request, it alerts the user, and waits for user input before
responding. This is analogous to the typical telephone user responding. This is analogous to the typical telephone user
experience, where the callee "answers" the call. experience, where the callee "answers" the call.
In contrast, the typical user experience for instant messaging In contrast, the typical user experience for instant messaging
applications is that the initial received message is immediately applications is that the initial received message is immediately
displayed to the user, without waiting for the user to "join" the displayed to the user, without waiting for the user to "join" the
conversation. Therefore, the principle of least surprise would conversation. Therefore, the principle of least surprise would
suggest that MSRP endpoints using SIP signaling SHOULD allow a mode suggest that MSRP endpoints using SIP signaling SHOULD allow a mode
where the endpoint quietly accepts the session, and begins displaying where the endpoint quietly accepts the session, and begins displaying
messages. messages.
This guideline may not make sense for all situations, such as for
mixed media applications, where both MSRP and audio sessions are
offered in the same INVITE. In general, good application design
should take precedence.
SIP INVITE requests may be forked by a SIP proxy, resulting in more SIP INVITE requests may be forked by a SIP proxy, resulting in more
than one endpoint receiving the same INVITE. SIP early media [27] than one endpoint receiving the same INVITE. SIP early media [28]
techniques can be used to establish a preliminary session with each techniques can be used to establish a preliminary session with each
endpoint, and canceling the INVITE transaction for any endpoints that endpoint so the initial message(s) are displayed on each endpoint,
do not send MSRP traffic after some period of time. and canceling the INVITE transaction for any endpoints that do not
send MSRP traffic after some period of time, so that they cease
receiving MSRP traffic from the inviter.
9. Formal Syntax 9. Formal Syntax
MSRP is a text protocol that uses the UTF-8 [14] transformation MSRP is a text protocol that uses the UTF-8 [14] transformation
format. format.
The following syntax specification uses the augmented Backus-Naur The following syntax specification uses the augmented Backus-Naur
Form (BNF) as described in RFC-2234 [6]. Form (BNF) as described in RFC-2234 [6].
msrp-req-or-resp = msrp-request / msrp-response msrp-req-or-resp = msrp-request / msrp-response
skipping to change at page 30, line 16 skipping to change at page 33, line 4
MSRP is a text protocol that uses the UTF-8 [14] transformation MSRP is a text protocol that uses the UTF-8 [14] transformation
format. format.
The following syntax specification uses the augmented Backus-Naur The following syntax specification uses the augmented Backus-Naur
Form (BNF) as described in RFC-2234 [6]. Form (BNF) as described in RFC-2234 [6].
msrp-req-or-resp = msrp-request / msrp-response msrp-req-or-resp = msrp-request / msrp-response
msrp-request = req-start headers [content-stuff] end-line msrp-request = req-start headers [content-stuff] end-line
msrp-response = resp-start headers end-line msrp-response = resp-start headers end-line
req-start = pMSRP SP transact-id SP method CRLF req-start = pMSRP SP transact-id SP method CRLF
resp-start = pMSRP SP transact-id SP status-code [SP phrase] CRLF resp-start = pMSRP SP transact-id SP status-code [SP comment] CRLF
phrase = utf8text comment = utf8text
pMSRP = %x4D.53.52.50 ; MSRP in caps pMSRP = %x4D.53.52.50 ; MSRP in caps
transact-id = ident transact-id = ident
method = mSEND / mREPORT / other-method method = mSEND / mREPORT / other-method
mSEND = %x53.45.4e.44 ; SEND in caps mSEND = %x53.45.4e.44 ; SEND in caps
mREPORT = %x52.45.50.4f.52.54; REPORT in caps mREPORT = %x52.45.50.4f.52.54; REPORT in caps
other-method = 1*UPALPHA other-method = 1*UPALPHA
status-code = 3DIGIT ; any code defined in this document status-code = 3DIGIT ; any code defined in this document
; or an extension document ; or an extension document
MSRP-URL = msrp-scheme "://" [userinfo "@"] hostport MSRP-URL = msrp-scheme "://" [userinfo "@"] hostport
["/" session-id] ";" transport ["/" session-id] ";" transport *( ";" url-parameter)
; userinfo as defined in RFC2396, except ; userinfo as defined in RFC3986, except
; limited to unreserved. ; limited to unreserved.
; hostport as defined in RFC3261 ; hostport as defined in RFC3261
; [Todo: update with RFC number for 2396bis]
msrp-scheme = "msrp" / "msrps" msrp-scheme = "msrp" / "msrps"
session-id = 1*( unreserved / "+" / "=" / "/" ) session-id = 1*( unreserved / "+" / "=" / "/" )
; unreserved as defined in RFC2396 ; unreserved as defined in RFC3986
transport = "tcp" / ALPHANUM transport = "tcp" / ALPHANUM
url-parameter = token ["=" token]
headers = To-Path CRLF From-Path CRLF 1*( header CRLF ) headers = To-Path CRLF From-Path CRLF 1*( header CRLF )
header = Message-ID header = Message-ID
/ Success-Report / Success-Report
/ Failure-Report / Failure-Report
/ Byte-Range / Byte-Range
/ Status / Status
/ ext-header / ext-header
To-Path = "To-Path:" SP MSRP-URL *( SP MSRP-URL ) To-Path = "To-Path:" SP MSRP-URL *( SP MSRP-URL )
From-Path = "From-Path:" SP MSRP-URL *( SP MSRP-URL ) From-Path = "From-Path:" SP MSRP-URL *( SP MSRP-URL )
Message-ID = "Message-ID:" SP ident Message-ID = "Message-ID:" SP ident
Success-Report = "Success-Report:" SP ("yes" / "no" ) Success-Report = "Success-Report:" SP ("yes" / "no" )
Failure-Report = "Failure-Report:" SP ("yes" / "no" / "partial" ) Failure-Report = "Failure-Report:" SP ("yes" / "no" / "partial" )
Byte-Range = "Byte-Range:" SP range-start "-" range-end "/" total Byte-Range = "Byte-Range:" SP range-start "-" range-end "/" total
range-start = 1*DIGIT range-start = 1*DIGIT
range-end = 1*DIGIT / "*" range-end = 1*DIGIT / "*"
total = 1*DIGIT / "*" total = 1*DIGIT / "*"
skipping to change at page 31, line 15 skipping to change at page 33, line 50
From-Path = "From-Path:" SP MSRP-URL *( SP MSRP-URL ) From-Path = "From-Path:" SP MSRP-URL *( SP MSRP-URL )
Message-ID = "Message-ID:" SP ident Message-ID = "Message-ID:" SP ident
Success-Report = "Success-Report:" SP ("yes" / "no" ) Success-Report = "Success-Report:" SP ("yes" / "no" )
Failure-Report = "Failure-Report:" SP ("yes" / "no" / "partial" ) Failure-Report = "Failure-Report:" SP ("yes" / "no" / "partial" )
Byte-Range = "Byte-Range:" SP range-start "-" range-end "/" total Byte-Range = "Byte-Range:" SP range-start "-" range-end "/" total
range-start = 1*DIGIT range-start = 1*DIGIT
range-end = 1*DIGIT / "*" range-end = 1*DIGIT / "*"
total = 1*DIGIT / "*" total = 1*DIGIT / "*"
Status = "Status:" SP namespace SP status-code [SP text-reason] Status = "Status:" SP namespace SP status-code [SP text-reason]
namespace = "000" namespace = 3(DIGIT); "000" for all codes defined in this document.
text-reason = utf8text text-reason = utf8text
ident = alphanum 3*31ident-char ident = alphanum 3*31ident-char
ident-char = alphanum / "." / "-" / "+" / "%" / "=" ident-char = alphanum / "." / "-" / "+" / "%" / "="
content-stuff = *(Other-Mime-Header CRLF) content-stuff = *(Other-Mime-Header CRLF)
Content-Type 2CRLF data CRLF Content-Type 2CRLF data CRLF
Content-Type = "Content-Type:" SP media-type Content-Type = "Content-Type:" SP media-type
media-type = type "/" subtype *( ";" gen-param ) media-type = type "/" subtype *( ";" gen-param )
skipping to change at page 32, line 38 skipping to change at page 35, line 28
This section summarizes the semantics of various response codes that This section summarizes the semantics of various response codes that
may be used in MSRP transaction responses. These codes may also be may be used in MSRP transaction responses. These codes may also be
used in the Status header in REPORT requests. used in the Status header in REPORT requests.
10.1 200 10.1 200
The 200 response code indicates a successful transaction. The 200 response code indicates a successful transaction.
10.2 400 10.2 400
A 400 response indicates a request was unintelligible. A 400 response indicates a request was unintelligible. The sender
may retry the request after correcting the error.
10.3 403 10.3 403
The action is not allowed. A 403 response indicates the attempted action is not allowed. The
sender should not try the request again.
10.4 408 10.4 408
A 408 response indicates that a downstream transaction did not A 408 response indicates that a downstream transaction did not
complete in the alloted time. It is never sent by any elements complete in the alloted time. It is never sent by any elements
described in this specification. However, 408 is used in the MSRP described in this specification. However, 408 is used in the MSRP
Relay extension; therefore MSRP endpoints may receive it. An Relay extension; therefore MSRP endpoints may receive it. An
endpoint MUST treat a 408 response in the same manner as it would endpoint MUST treat a 408 response in the same manner as it would
treat a local timeout. treat a local timeout.
10.5 413 10.5 413
A 413 response indicates that the receiver wishes the sender to stop A 413 response indicates that the receiver wishes the sender to stop
sending the particular message. Typically, a 413 is sent in response sending the particular message. Typically, a 413 is sent in response
to a chunk of an undesired message. to a chunk of an undesired message.
If a message sender receives a 413 in a response, or in a REPORT If a message sender receives a 413 in a response, or in a REPORT
request, it MUST NOT send any further chunks in the message, that is, request, it MUST NOT send any further chunks in the message, that is,
any further chunks with the same Message-ID value. If the sender any further chunks with the same Message-ID value. If the sender
receives the 413 while in the process of sending a chunk, and the receives the 413 while in the process of sending a chunk, and the
chunk is interruptible, the sender MUST abort sending the chunk. chunk is interruptible, the sender MUST interrupt it.
10.6 415 10.6 415
A 415 response indicates the SEND request contained a MIME A 415 response indicates the SEND request contained a MIME content-
content-type that is not understood by the receiver. type that is not understood by the receiver. The sender should not
send any further messages with the same content-type for the duration
of the session.
10.7 423 10.7 423
A 423 response indicates that one of the requested parameters is out A 423 response indicates that one of the requested parameters is out
of bounds. It is used by the relay extensions to this document. of bounds. It is used by the relay extensions to this document.
10.8 426 10.8 426
A 426 response indicates that the request is only allowed over TLS A 426 response indicates that the request is only allowed over secure
protected connections. connections.
10.9 481 10.9 481
A 481 response indicates that the indicated session does not exist. A 481 response indicates that the indicated session does not exist.
The sender should terminate the session.
10.10 501 10.10 501
A 501 response indicates that the recipient does not understand the A 501 response indicates that the recipient does not understand the
request method. request method.
The 501 response code exists to allow some degree of method The 501 response code exists to allow some degree of method
extensibility. It is not intended as a license to ignore methods extensibility. It is not intended as a license to ignore methods
defined in this document; rather it is a mechanism to report lack defined in this document; rather it is a mechanism to report lack
of support of extension methods. of support of extension methods.
10.11 506 10.11 506
A 506 response indicates that a request arrived on a session which is A 506 response indicates that a request arrived on a session which is
already bound to another network connection. already bound to another network connection. The sender should cease
sending messages for that session on this connection.
11. Examples 11. Examples
11.1 Basic IM session 11.1 Basic IM session
This section shows an example flow for the most common scenario. The This section shows an example flow for the most common scenario. The
example assumes SIP is used to transport the SDP exchange. Details example assumes SIP is used to transport the SDP exchange. Details
of the SIP messages and SIP proxy infrastructure are omitted for the of the SIP messages and SIP proxy infrastructure are omitted for the
sake of brevity. In the example, assume the offerer is sake of brevity. In the example, assume the offerer is
sip:alice@example.com and the answerer is sip:bob@example.com. sip:alice@example.com and the answerer is sip:bob@example.com.
skipping to change at page 34, line 50 skipping to change at page 37, line 47
1. Alice constructs a local URL of 1. Alice constructs a local URL of
msrp://alicepc.example.com:7777/iau39;tcp . msrp://alicepc.example.com:7777/iau39;tcp .
Alice->Bob (SIP): INVITE sip:bob@example.com Alice->Bob (SIP): INVITE sip:bob@example.com
v=0 v=0
o=alice 2890844557 2890844559 IN IP4 alicepc.example.com o=alice 2890844557 2890844559 IN IP4 alicepc.example.com
s= s=
c=IN IP4 alicepc.example.com c=IN IP4 alicepc.example.com
t=0 0 t=0 0
m=message 7777 msrp/tcp * m=message 7777 TCP/MSRP *
a=accept-types:text/plain a=accept-types:text/plain
a=path:msrp://alicepc.example.com:7777/iau39;tcp a=path:msrp://alicepc.example.com:7777/iau39;tcp
2. Bob listens on port 8888, and sends the following response: 2. Bob listens on port 8888, and sends the following response:
Bob->Alice (SIP): 200 OK Bob->Alice (SIP): 200 OK
v=0 v=0
o=bob 2890844612 2890844616 IN IP4 bob.example.com o=bob 2890844612 2890844616 IN IP4 bob.example.com
s= s=
c=IN IP4 bob.example.com c=IN IP4 bob.example.com
t=0 0 t=0 0
m=message 8888 msrp/tcp * m=message 8888 TCP/MSRP *
a=accept-types:text/plain a=accept-types:text/plain
a=path:msrp://bob.example.com:8888/9di4ea;tcp a=path:msrp://bob.example.com:8888/9di4ea;tcp
3. Alice->Bob (SIP): ACK 3. Alice->Bob (SIP): ACK sip:bob@example.com
4. (Alice opens connection to Bob.) Alice->Bob (MSRP): 4. (Alice opens connection to Bob.) Alice->Bob (MSRP):
MSRP d93kswow SEND MSRP d93kswow SEND
To-Path:msrp://bob.example.com:8888/9di4ea;tcp To-Path:msrp://bob.example.com:8888/9di4ea;tcp
From-Path:msrp://alicepc.example.com:7777/iau39;tcp From-Path:msrp://alicepc.example.com:7777/iau39;tcp
Message-ID: 12339sdqwer Message-ID: 12339sdqwer
Content-Type: text/plain Content-Type: text/plain
Hi, I'm Alice! Hi, I'm Alice!
-------d93kswow$ -------d93kswow$
5. Bob->Alice (MSRP): 5. Bob->Alice (MSRP):
MSRP d93kswow 200 OK MSRP d93kswow 200 OK
To-Path:msrp://bob.example.com:8888/9di4ea;tcp To-Path: msrp://alicepc.example.com:7777/iau39;tcp
From-Path:msrp://alicepc.example.com:7777/iau39;tcp From-Path: msrp://bob.example.com:8888/9di4ea;tcp
-------d93kswow$ -------d93kswow$
6. Bob->Alice (MSRP): 6. Bob->Alice (MSRP):
MSRP dkei38sd SEND MSRP dkei38sd SEND
To-Path:msrp://alice.example.com:7777/iau39;tcp To-Path: msrp://alicepc.example.com:7777/iau39;tcp
From-Path:msrp://bob.example.com:8888/9di4ea;tcp From-Path:msrp://bob.example.com:8888/9di4ea;tcp
Message-ID: 456 Message-ID: 456
Content-Type: text/plain Content-Type: text/plain
Hi, Alice! I'm Bob! Hi, Alice! I'm Bob!
-------dkei38sd$ -------dkei38sd$
7. Alice->Bob (MSRP): 7. Alice->Bob (MSRP):
MSRP dkei38sd 200 OK MSRP dkei38sd 200 OK
To-Path:msrp://alice.example.com:7777/iau39;tcp To-Path: msrp://alicepc.example.com:7777/iau39;tcp
From-Path:msrp://bob.example.com:8888/9di4ea;tcp From-Path:msrp://bob.example.com:8888/9di4ea;tcp
-------dkei38sd$ -------dkei38sd$
8. Alice->Bob (SIP): BYE 8. Alice->Bob (SIP): BYE sip:bob@example.com
Alice invalidates local session state. Alice invalidates local session state.
9. Bob invalidates local state for the session. 9. Bob invalidates local state for the session.
Bob->Alice (SIP): 200 OK Bob->Alice (SIP): 200 OK
11.2 Message with XHTML Content 11.2 Message with XHTML Content
MSRP dsdfoe38sd SEND MSRP dsdfoe38sd SEND
skipping to change at page 37, line 20 skipping to change at page 40, line 18
11.5 Positive Report 11.5 Positive Report
Alice->Bob (MSRP): Alice->Bob (MSRP):
MSRP d93kswow SEND MSRP d93kswow SEND
To-Path:msrp://bob.example.com:8888/9di4ea;tcp To-Path:msrp://bob.example.com:8888/9di4ea;tcp
From-Path:msrp://alicepc.example.com:7777/iau39;tcp From-Path:msrp://alicepc.example.com:7777/iau39;tcp
Message-ID: 12339sdqwer Message-ID: 12339sdqwer
Success-Report: yes Success-Report: yes
Failure-Report: no
Content-Type: text/html Content-Type: text/html
<html><body> <html><body>
<p>Here is that important link... <p>Here is that important link...
<a href="www.example.com/foobar">foobar</a> <a href="www.example.com/foobar">foobar</a>
</p> </p>
</body></html> </body></html>
-------d93kswow$ -------d93kswow$
Bob->Alice (MSRP): Bob->Alice (MSRP):
MSRP d93kswow 200 OK
To-Path:msrp://alicepc.example.com:7777/iau39;tcp
From-Path:msrp://bob.example.com:8888/9di4ea;tcp
-------d93kswow$
Bob->Alice (MSRP):
MSRP dkei38sd REPORT MSRP dkei38sd REPORT
To-Path:msrp://alicepc.example.com:7777/iau39;tcp To-Path:msrp://alicepc.example.com:7777/iau39;tcp
From-Path:msrp://bob.example.com:8888/9di4ea;tcp From-Path:msrp://bob.example.com:8888/9di4ea;tcp
Message-ID: 12339sdqwer Message-ID: 12339sdqwer
Status: 000 200 OK Status: 000 200 OK
-------dkei38sd$ -------dkei38sd$
11.6 Forked IM 11.6 Forked IM
Traditional IM systems generally do a poor job of handling multiple Traditional IM systems generally do a poor job of handling multiple
simultaneous IM clients online for the same person. While some do a simultaneous IM clients online for the same person. While some do a
better job than many existing systems, handling of multiple clients better job than many existing systems, handling of multiple clients
is fairly crude. This becomes a much more significant issue when is fairly crude. This becomes a much more significant issue when
always-on mobile devices are available, but when it is desirable to always-on mobile devices are available, but it is desirable to use
use them only if another IM client is not available. them only if another IM client is not available.
Using SIP makes rendezvous decisions explicit, deterministic, and Using SIP makes rendezvous decisions explicit, deterministic, and
very flexible; instead "pager-mode" IM systems use implicit very flexible; instead "pager-mode" IM systems use implicit
implementation-specific decisions which IM clients cannot influence. implementation-specific decisions which IM clients cannot influence.
With SIP session mode messaging rendezvous decisions can be under With SIP session mode messaging rendezvous decisions can be under
control of the client in a predictable, interoperable way for any control of the client in a predictable, interoperable way for any
host that implements callee capabilities [29]. As a result, host that implements callee capabilities [30]. As a result,
rendezvous policy is managed consistently for each address of record. rendezvous policy is managed consistently for each address of record.
The following example shows Juliet with several IM clients where she The following example shows Juliet with several IM clients where she
can be reached. Each of these has a unique SIP Contact and MSRP can be reached. Each of these has a unique SIP Contact and MSRP
session. The example takes advantage of SIP's capability to "fork" session. The example takes advantage of SIP's capability to "fork"
an invitation to several Contacts in parallel, in sequence, or in an invitation to several Contacts in parallel, in sequence, or in
combination. Juliet has registered from her chamber, the balcony, combination. Juliet has registered from her chamber, the balcony,
her PDA, and as a last resort, you can leave a message with her her PDA, and as a last resort, you can leave a message with her
Nurse. Juliet's contacts are listed below. The q-values express Nurse. Juliet's contacts are listed below. The q-values express
relative preference (q=1.0 is the highest preference). relative preference (q=1.0 is the highest preference).
skipping to change at page 39, line 9 skipping to change at page 41, line 48
Contact: <sip:juliet@balcony.thecapulets.example.com> Contact: <sip:juliet@balcony.thecapulets.example.com>
;q=0.9;expires=3600 ;q=0.9;expires=3600
Contact: <sip:juliet@chamber.thecapulets.example.com> Contact: <sip:juliet@chamber.thecapulets.example.com>
;q=1.0;expires=3600 ;q=1.0;expires=3600
Contact: <sip:jcapulet@veronamobile.example.net>;q=0.4;expires=3600 Contact: <sip:jcapulet@veronamobile.example.net>;q=0.4;expires=3600
Contact: <sip:nurse@thecapulets.example.com>;q=0.1;expires=3600 Contact: <sip:nurse@thecapulets.example.com>;q=0.1;expires=3600
When Romeo opens his IM program, he selects Juliet and types the When Romeo opens his IM program, he selects Juliet and types the
message "art thou hither?" (instead of "you there?"). His client message "art thou hither?" (instead of "you there?"). His client
sends a SIP invitation to sip:juliet@thecapulets.example.com. The sends a SIP invitation to sip:juliet@thecapulets.example.com. The
Proxy there tries first the balcony and the chamber simultaneously. proxy there tries first the balcony and the chamber simultaneously.
A client is running on both those systems, both of which setup early A client is running on both those systems, both of which setup early
sessions of MSRP with Romeo's client. The client automatically sends sessions of MSRP with Romeo's client. The client automatically sends
the message over the MSRPS to the two MSRP URIs involved. After a the message over MSRPS to the two MSRP URIs involved. After a delay
delay of a several seconds with no reply or activity from Juliet, the of a several seconds with no reply or activity from Juliet, the proxy
proxy cancels the invitation at her first two contacts, and forwards cancels the invitation at her first two contacts, and forwards the
the invitation on to Juliet's PDA. Since her father is talking to invitation on to Juliet's PDA. Since her father is talking to her
her about her wedding, she selects "Do Not Disturb" on her PDA, which about her wedding, she selects "Do Not Disturb" on her PDA, which
sends a "Busy Here" response. The proxy then tries the Nurse, who sends a "Busy Here" response. The proxy then tries the Nurse, who
answers and tells Romeo what is going on. answers and tells Romeo what is going on.
Romeo Juliet's Juliet/ Juliet/ Juliet/ Nurse Romeo Juliet's Juliet/ Juliet/ Juliet/ Nurse
Proxy balcony chamber PDA Proxy balcony chamber PDA
| | | | | | | | | | | |
|--INVITE--->| | | | | |--INVITE--->| | | | |
| |--INVITE--->| | | | | |--INVITE--->| | | |
| |<----180----| | | | | |<----180----| | | |
skipping to change at page 40, line 17 skipping to change at page 43, line 49
| |----ACK----------------------------->| | | |----ACK----------------------------->| |
| | | | | | | | | | | |
| |--INVITE---------------------------------------->| | |--INVITE---------------------------------------->|
| |<---200 OK---------------------------------------| | |<---200 OK---------------------------------------|
|<--200 OK---| | | | | |<--200 OK---| | | | |
|---ACK------------------------------------------------------->| |---ACK------------------------------------------------------->|
|<================MSRP Session================================>| |<================MSRP Session================================>|
| | | | | | | | | | | |
| Hi Romeo, Juliet is | | Hi Romeo, Juliet is |
| with her father now | | with her father now |
| can i take a message?| | can I take a message?|
| | | |
| Tell her to go to confession tomorrow.... | | Tell her to go to confession tomorrow.... |
12. Extensibility 12. Extensibility
MSRP was designed to be only minimally extensible. New MSRP Methods, MSRP was designed to be only minimally extensible. New MSRP Methods,
Headers, and status codes can be defined in standards track RFCs. Headers, and status codes can be defined in standards track RFCs.
There is no registry of headers, methods, or status codes, since the There is no registry of headers, methods, or status codes, since the
number of new elements and total extensions is expected to be very number of new elements and total extensions is expected to be very
small. MSRP does not contain a version number or any negotiation small. MSRP does not contain a version number or any negotiation
mechanism to require or discover new features. If a mechanism to require or discover new features. If a non-
non-interoperable update or extension occurs in the future, it will interoperable update or extension occurs in the future, it will be
be treated as a new protocol, and must describe how its use will be treated as a new protocol, and must describe how its use will be
signaled. signaled.
In order to allow extension header fields without breaking In order to allow extension header fields without breaking
interoperability, if an MSRP device receives a request or response interoperability, if an MSRP device receives a request or response
containing a header field that it does not understand, it MUST ignore containing a header field that it does not understand, it MUST ignore
the header field and process the request or response as if the header the header field and process the request or response as if the header
field was not present. If an MSRP device receives a request with an field was not present. If an MSRP device receives a request with an
unknown method, it MUST return a 501 response. unknown method, it MUST return a 501 response.
MSRP was designed to use lists of URLs instead of a single URL in the MSRP was designed to use lists of URLs instead of a single URL in the
To-Path and From-Path headers in anticipation of relay or gateway To-Path and From-Path headers in anticipation of relay or gateway
functionality being added. In addition, msrp: and msrps: URLs can functionality being added. In addition, msrp: and msrps: URLs can
contain parameters which are extensible. contain parameters which are extensible.
13. CPIM compatibility 13. CPIM compatibility
MSRP sessions may go to a gateway to other CPIM [24] compatible MSRP sessions may go to a gateway to other CPIM [25] compatible
protocols. If this occurs, the gateway MUST maintain session state, protocols. If this occurs, the gateway MUST maintain session state,
and MUST translate between the MSRP session semantics and CPIM and MUST translate between the MSRP session semantics and CPIM
semantics, which do not include a concept of sessions. Furthermore, semantics, which do not include a concept of sessions. Furthermore,
when one endpoint of the session is a CPIM gateway, instant messages when one endpoint of the session is a CPIM gateway, instant messages
SHOULD be wrapped in "message/cpim" [12] bodies. Such a gateway MUST SHOULD be wrapped in "message/cpim" [12] bodies. Such a gateway MUST
include "message/cpim" as the first entry in its SDP accept-types include "message/cpim" as the first entry in its SDP accept-types
attribute. MSRP endpoints sending instant messages to a peer that attribute. MSRP endpoints sending instant messages to a peer that
has included 'message/cpim" as the first entry in the accept-types has included "message/cpim" as the first entry in the accept-types
attribute SHOULD encapsulate all instant message bodies in attribute SHOULD encapsulate all instant message bodies in "message/
"message/cpim" wrappers. All MSRP endpoints MUST support the cpim" wrappers. All MSRP endpoints MUST support the message/cpim
message/cpim type, and SHOULD support the S/MIME features of that type, and SHOULD support the S/MIME features of that format.
format.
If a message is to be wrapped in a message/cpim envelope, the If a message is to be wrapped in a message/cpim envelope, the
wrapping MUST be done prior to breaking the message into chunks, if wrapping MUST be done prior to breaking the message into chunks, if
needed. needed.
All MSRP endpoints MUST recognize the From, To, DateTime, and Require All MSRP endpoints MUST recognize the From, To, DateTime, and Require
headers as defined in RFC3862. Such applications SHOULD recognize headers as defined in RFC3862. Such applications SHOULD recognize
the CC header, and MAY recognize the Subject header. Any MSRP the CC header, and MAY recognize the Subject header. Any MSRP
application that recognizes any message/cpim header MUST understand application that recognizes any message/cpim header MUST understand
the NS (name space) header. the NS (name space) header.
All message/cpim body parts sent by an MSRP endpoint MUST include the All message/cpim body parts sent by an MSRP endpoint MUST include the
From and To headers. If the message/cpim body part is protected From and To headers. If the message/cpim body part is protected
using S/MIME, then it MUST also include the DateTime header. using S/MIME, then it MUST also include the DateTime header.
The NS, To, and CC headers may occur multiple times. Other headers The NS, To, and CC headers may occur multiple times. Other headers
defined in RFC3862 MUST NOT occur more than once in a given defined in RFC3862 MUST NOT occur more than once in a given message/
message/cpim body part in an MSRP message. The Require header MAY cpim body part in an MSRP message. The Require header MAY include
include multiple values. The NS header MAY occur zero or more times, multiple values. The NS header MAY occur zero or more times,
depending on how many name spaces are being referenced. depending on how many name spaces are being referenced.
Extension headers MAY occur more than once, depending on the Extension headers MAY occur more than once, depending on the
definition of such headers. definition of such headers.
Using message/cpim envelopes are also useful if an MSRP device Using message/cpim envelopes are also useful if an MSRP device
wishes to send a message on behalf of some other identity. The wishes to send a message on behalf of some other identity. The
device may add a message/cpim envelope with the appropriate From device may add a message/cpim envelope with the appropriate From
header value. header value.
skipping to change at page 42, line 11 skipping to change at page 45, line 39
governments for communicating important information. Like many governments for communicating important information. Like many
communications systems, the properties of Integrity and communications systems, the properties of Integrity and
Confidentiality of the exchanged information, along with the Confidentiality of the exchanged information, along with the
possibility of Anonymous communications, and knowing you are possibility of Anonymous communications, and knowing you are
communicating with the correct other party are required. MSRP pushes communicating with the correct other party are required. MSRP pushes
many of the hard problems to SIP when SIP sets up the session, but many of the hard problems to SIP when SIP sets up the session, but
some of the problems remain. Spam and DoS attacks are also very some of the problems remain. Spam and DoS attacks are also very
relevant to IM systems. relevant to IM systems.
MSRP needs to provide confidentiality and integrity for the messages MSRP needs to provide confidentiality and integrity for the messages
it transfers. It also needs to provide assurances the connected host it transfers. It also needs to provide assurances that the connected
is the host that it meant to connect to and that the connection has host is the host that it meant to connect to and that the connection
not been hijacked. has not been hijacked.
14.1 Transport Level Protection 14.1 Transport Level Protection
When using only TCP connections, MSRP security is fairly weak. If When using only TCP connections, MSRP security is fairly weak. If
host A is contacting B, B passes its hostname and a secret to A using host A is contacting B, B passes its hostname and a secret to A using
a rendezvous protocol. Although MSRP requires the use of a a rendezvous protocol. Although MSRP requires the use of a
rendezvous protocol with the ability to protect this exchange, there rendezvous protocol with the ability to protect this exchange, there
is no guarantee that the protection will be used all the time. If is no guarantee that the protection will be used all the time. If
such protection is not used, anyone can see this secret. A then such protection is not used, anyone can see this secret. A then
connects to the provided host name and passes the secret in the clear connects to the provided host name and passes the secret in the clear
across the connection to B. A assumes that it is talking to B based across the connection to B. A assumes that it is talking to B based
on where it sent the SYN packet and then delivers the secret in plain on where it sent the SYN packet and then delivers the secret in plain
text across the connections. B assumes it is talking to A because text across the connections. B assumes it is talking to A because
the host on the other end of the connection delivered the secret. An the host on the other end of the connection delivered the secret. An
attacker that could ACK the SYN packet could insert itself as a man attacker that could ACK the SYN packet could insert itself as a man
in the middle in the connection. in the middle in the connection.
When using TLS connections, the security is significantly improved. When using TLS connections, the security is significantly improved.
We assume that the host accepting the connection has a certificate We assume that the host accepting the connection has a certificate
from a well know certificate authority. Furthermore, we assume that from a well known certificate authority. Furthermore, we assume that
the signaling to set up the session is protected by the rendezvous the signaling to set up the session is protected by the rendezvous
protocol. In this case, when host A contacts host B, the secret is protocol. In this case, when host A contacts host B, the secret is
passed through a confidential channel to A. A connects with TLS to passed through a confidential channel to A. A connects with TLS to B.
B. B presents a valid certificate, so A knows it really is connected B presents a valid certificate, so A knows it really is connected to
to B. A then delivers the secret provided by B, so that B can verify B. A then delivers the secret provided by B, so that B can verify it
it is connected to A. In this case, a rogue SIP Proxy can see the is connected to A. In this case, a rogue SIP Proxy can see the secret
secret in the SIP signaling traffic and could potentially insert in the SIP signaling traffic and could potentially insert itself as a
itself as a man-in-the-middle. man-in-the-middle.
Realistically, using TLS is difficult for peer to peer connections, Realistically, using TLS is difficult for peer to peer connections,
as the types of hosts that end clients use for sending instant as the types of hosts that end clients use for sending instant
messages are unlikely to have long term stable IP addresses or DNS messages are unlikely to have long term stable IP addresses or DNS
names that certificate can bind to. In addition, the cost of server names that certificates can bind to. In addition, the cost of server
certificates from well known certificate authorities is currently certificates from well known certificate authorities is currently
expensive enough to discourage their use for each client. While not expensive enough to discourage their use for each client. While not
in scope for this document, using TLS with a DH profile is possible. in scope for this document, using TLS with a DH profile is possible.
TLS becomes much more practical when some form of relay is TLS becomes much more practical when some form of relay is
introduced. Clients can then form TLS connections to relays, which introduced. Clients can then form TLS connections to relays, which
are much more likely to have TLS certificates. While this are much more likely to have TLS certificates. While this
specification does not address such relays, they are described by a specification does not address such relays, they are described by a
companion document [20]. That document makes extensive use of TLS to companion document [21]. That document makes extensive use of TLS to
protect traffic between clients and relays, and between one relay and protect traffic between clients and relays, and between one relay and
another. another.
TLS is used to authenticate devices and to provide integrity and TLS is used to authenticate devices and to provide integrity and
confidentiality for the headers being transported. MSRP elements confidentiality for the headers being transported. MSRP elements
MUST implement TLS and MUST also implement the TLS MUST implement TLS and MUST also implement the TLS
ClientExtendedHello extended hello information for server name ClientExtendedHello extended hello information for server name
indication as described in [10]. A TLS cipher-suite of indication as described in [10]. A TLS cipher-suite of
TLS_RSA_WITH_AES_128_CBC_SHA [13] MUST be supported (other TLS_RSA_WITH_AES_128_CBC_SHA [13] MUST be supported (other cipher-
cipher-suites MAY also be supported). suites MAY also be supported).
14.2 S/MIME 14.2 S/MIME
The only strong security for non-TLS connections is achieved using The only strong security for non-TLS connections is achieved using
S/MIME. S/MIME.
Since MSRP carries arbitrary MIME content, it can trivially carry Since MSRP carries arbitrary MIME content, it can trivially carry
S/MIME protected messages as well. All MSRP implementations MUST S/MIME protected messages as well. All MSRP implementations MUST
support the multipart/signed MIME type even if they do not support support the multipart/signed MIME type even if they do not support
S/MIME. Since SIP can carry a session key, S/MIME messages in the S/MIME. Since SIP can carry a session key, S/MIME messages in the
context of a session could also be protected using a key-wrapped context of a session could also be protected using a key-wrapped
shared secret [25] provided in the session setup. MSRP is a binary shared secret [26] provided in the session setup. MSRP is a binary
protocol and MIME bodies MUST be transfered with a transfer encoding protocol and MIME bodies MUST be transferred with a transfer encoding
of binary. If a message is both signed and encrypted, it SHOULD be of binary. If a message is both signed and encrypted, it SHOULD be
signed first, then encrypted. If S/MIME is supported, SHA-1, RSA, signed first, then encrypted. If S/MIME is supported, SHA-1, RSA,
and AES-128 MUST be supported. and AES-128 MUST be supported.
This does not actually require the endpoint to have certificates from This does not actually require the endpoint to have certificates from
a well known certificate authority. When MSRP is used with SIP, the a well known certificate authority. When MSRP is used with SIP, the
Identity [21] and Certificates [22] mechanism provides S/MIME based Identity [22] and Certificates [23] mechanisms provide S/MIME based
delivery of a secret between A and B. No SIP intermediary except the delivery of a secret between A and B. No SIP intermediary except the
explicitly trusted authentication service (one per user) can see the explicitly trusted authentication service (one per user) can see the
secret. The S/MIME encryption of the SDP can also be used by SIP to secret. The S/MIME encryption of the SDP can also be used by SIP to
exchange keying material that can be used in MRSP. The MSRP session exchange keying material that can be used in MSRP. The MSRP session
can then use S/MIME with this keying material to encrypt and sign can then use S/MIME with this keying material to encrypt and sign
messages sent over MSRP. The connection can still be hijacked since messages sent over MSRP. The connection can still be hijacked since
the secret is sent in clear text to the other end of the TCP the secret is sent in clear text to the other end of the TCP
connection, but the consequences are mitigated if all the MSRP connection, but the consequences are mitigated if all the MSRP
content is encrypted and signed with S/MIME. It is out of scope for content is encrypted and signed with S/MIME. It is out of scope for
this document but there is nothing stopping the SIP negotiation of this document but there is nothing stopping the SIP negotiation of
MSRP session from negotiating symmetric keying material that is used MSRP session from negotiating symmetric keying material that is used
with S/MIME for integrity and privacy. with S/MIME for integrity and privacy.
14.3 Other Security Concerns 14.3 Other Security Concerns
skipping to change at page 44, line 27 skipping to change at page 48, line 4
SIP is attempting to address issues in dealing with spam. The spam SIP is attempting to address issues in dealing with spam. The spam
issue is probably best dealt with at the SIP level when an MSRP issue is probably best dealt with at the SIP level when an MSRP
session is initiated and not at the MSRP level. session is initiated and not at the MSRP level.
If a sender chooses to employ S/MIME to protect a message, all S/MIME If a sender chooses to employ S/MIME to protect a message, all S/MIME
operations MUST occur prior to breaking the message into chunks, if operations MUST occur prior to breaking the message into chunks, if
needed. needed.
The signaling will have set up the session to or from some specific The signaling will have set up the session to or from some specific
URLs that will often have "im:" or "sip:" URI schemes. When the URLs that will often have "im:" or "sip:" URI schemes. When the
signaling has been set up to a specific end users, and S/MIME is signaling has been set up to a specific end user, and S/MIME is
implemented, then the client needs to verify that the name in the implemented, then the client needs to verify that the name in the
SubjectAltName of the certificate contains an entry that matches the SubjectAltName of the certificate contains an entry that matches the
URI that was used for the other end in the signaling. There are some URI that was used for the other end in the signaling. There are some
cases, such as IM conferencing, where the S/MIME certificate name and cases, such as IM conferencing, where the S/MIME certificate name and
the signaled identity will not match. In these cases the client the signaled identity will not match. In these cases the client
should ensure that the user is informed that the message came from should ensure that the user is informed that the message came from
the user identified in the certificate and does not assume that the the user identified in the certificate and does not assume that the
message came from the party they signaled. message came from the party they signaled.
In some cases, a sending device may need to attribute a message to In some cases, a sending device may need to attribute a message to
skipping to change at page 45, line 30 skipping to change at page 49, line 9
conference server. The recipient's endpoint should determine its conference server. The recipient's endpoint should determine its
level of trust of the authenticity of the sender independently for level of trust of the authenticity of the sender independently for
each session. The fact that an endpoint trusts the authenticity of each session. The fact that an endpoint trusts the authenticity of
the sender on any given session should not affect the level of trust the sender on any given session should not affect the level of trust
it assigns for apparently the same sender on a different session. it assigns for apparently the same sender on a different session.
When MSRP clients form or acquire a certificate, they SHOULD ensure When MSRP clients form or acquire a certificate, they SHOULD ensure
that the subjectAltName has a GeneralName entry of type that the subjectAltName has a GeneralName entry of type
uniformResourceIdentifier for each URL corresponding to this client uniformResourceIdentifier for each URL corresponding to this client
and should always include an "im:" URI. It is fine if the and should always include an "im:" URI. It is fine if the
certificate contains other URIs such as an "sip:" or "xmpp:" URIs. certificate contains other URIs such as "sip:" or "xmpp:" URIs.
MSRP implementors should be aware of a potential attack on MSRP MSRP implementors should be aware of a potential attack on MSRP
devices that involves placing very large values in the byte-range devices that involves placing very large values in the byte-range
header field, potentially causing the device to allocate very large header field, potentially causing the device to allocate very large
memory buffers to hold the message. Implementations SHOULD apply memory buffers to hold the message. Implementations SHOULD apply
some degree of sanity checking on byte-range values before allocating some degree of sanity checking on byte-range values before allocating
such buffers. such buffers.
15. IANA Considerations 15. IANA Considerations
15.1 MSRP Port This specification requests the IANA to create a registry for MSRP
parameters under http://www.iana.org/assignments/msrp-parameters.
This section further introduces sub-registries for MSRP method names,
status codes, and header field names.
[Note to RFC Editor: Please replace all occurrences of RFCXXXX in
this section with the actual number assigned to this document.]
15.1 MSRP Method Names
This specification establishes the Method sub-registry under
http://www.iana.org/assignments/msrp-parameters and initiates its
population as follows:
SEND - [RFCXXXX]
REPORT - [RFCXXXX]
The following information must be provided in an RFC publication in
order to register a new MSRP Method:
The method name.
The RFC number in which the method is registered.
15.2 MSRP Header Fields
This specification establishes the Header-Field sub-registry under
http://www.iana.org/assignments/msrp-parameters. Its initial
population is defined as follows:
To-Path - [RFCXXXX]
From-Path - [RFCXXXX]
Success-Report - [RFCXXXX]
Failure-Report - [RFCXXXX]
Byte-Range - [RFCXXXX]
Status - [RFCXXXX]
The following information must be provided in an RFC publication in
order to register a new MSRP Method:
The header field name.
The RFC number in which the method is registered.
15.3 MSRP Status Codes
This specification establishes the Status-Code sub-registry under
http://www.iana.org/assignments/msrp-parameters. Its initial
population is defined in Section 10. It takes the following format:
Code [RFC Number]
The following information must be provided in an RFC publication in
order to register a new MSRP Method:
The status code number.
The RFC number in which the method is registered.
15.4 MSRP Port
MSRP uses TCP port XYX, to be determined by IANA after this document MSRP uses TCP port XYX, to be determined by IANA after this document
is approved for publication. Usage of this value is described in is approved for publication. Usage of this value is described in
Section 6 Section 6
15.2 MSRP URL Schemes 15.5 MSRP URL Schemes
This document defines the URL schemes of "msrp" and "msrps". This document defines the URL schemes of "msrp" and "msrps".
Syntax: See Section 6. Syntax: See Section 6.
Character Encoding: See Section 6. Character Encoding: See Section 6.
Intended Usage: See Section 6. Intended Usage: See Section 6.
Protocols: The Message Session Relay Protocol (MSRP). Protocols: The Message Session Relay Protocol (MSRP).
Security Considerations: See Section 14. Security Considerations: See Section 14.
Relevant Publications: RFCXXXX Relevant Publications: RFCXXXX
[Note to RFC Editor: Please replace RFCXXXX in the above
paragraph with the actual number assigned to this document.
15.3 SDP Transport Protocol 15.6 SDP Transport Protocol
MSRP defines the a new SDP protocol field value "msrp/tcp", which MSRP defines the a new SDP protocol field values "TCP/MSRP" and "TCP/
should be registered in the sdp-parameters registry under "proto". TLS/MSRP", which should be registered in the sdp-parameters registry
This value indicates the MSRP protocol when TCP is used as an under "proto". This first value indicates the MSRP protocol when TCP
underlying transport. is used as an underlying transport. The second indicates that TLS is
used.
Specifications defining new protocol values must define the rules for Specifications defining new protocol values must define the rules for
the associated media format namespace. The "msrp/tcp" protocol value the associated media format namespace. The "TCP/MSRP" and "TCP/TLS/
allows only one value in the format field (fmt), which is a single MSRP" protocol values allow only one value in the format field (fmt),
occurrence of "*". Actual format determination is made using the which is a single occurrence of "*". Actual format determination is
"accept-types" and "accept-wrapped-types" attributes. made using the "accept-types" and "accept-wrapped-types" attributes.
15.4 SDP Attribute Names 15.7 SDP Attribute Names
This document registers the following SDP attribute parameter names This document registers the following SDP attribute parameter names
in the sdp-parameters registry. These names are to be used in the in the sdp-parameters registry. These names are to be used in the
SDP att-name field. SDP att-name field.
15.4.1 Accept Types 15.7.1 Accept Types
Contact Information: Ben Campbell (ben@estacado.net) Contact Information: Ben Campbell (ben@estacado.net)
Attribute-name: accept-types Attribute-name: accept-types
Long-form Attribute Name: Acceptable MIME Types Long-form Attribute Name: Acceptable MIME Types
Type: Media level Type: Media level
Subject to Charset Attribute: No Subject to Charset Attribute: No
Purpose and Appropriate Values: The "accept-types" attribute contains Purpose and Appropriate Values: The "accept-types" attribute contains
a list of MIME content-types that the endpoint is willing to a list of MIME content-types that the endpoint is willing to
receive. It may contain zero or more registered MIME types, or receive. It may contain zero or more registered MIME types, or
"*" in a space delimited string. "*" in a space delimited string.
15.4.2 Wrapped Types 15.7.2 Wrapped Types
Contact Information: Ben Campbell (ben@estacado.net) Contact Information: Ben Campbell (ben@estacado.net)
Attribute-name: accept-wrapped-types Attribute-name: accept-wrapped-types
Long-form Attribute Name: Acceptable MIME Types Inside Wrappers Long-form Attribute Name: Acceptable MIME Types Inside Wrappers
Type: Media level Type: Media level
Subject to Charset Attribute: No Subject to Charset Attribute: No
Purpose and Appropriate Values: The "accept-wrapped-types" attribute Purpose and Appropriate Values: The "accept-wrapped-types" attribute
contains a list of MIME content-types that the endpoint is willing contains a list of MIME content-types that the endpoint is willing
to receive in an MSRP message with multipart content, but may not to receive in an MSRP message with multipart content, but may not
be used as the outermost type of the message. It may contain zero be used as the outermost type of the message. It may contain zero
or more registered MIME types, or "*" in a space delimited string. or more registered MIME types, or "*" in a space delimited string.
15.4.3 Max Size 15.7.3 Max Size
Contact Information: Ben Campbell (ben@estacado.net) Contact Information: Ben Campbell (ben@estacado.net)
Attribute-name: max-size Attribute-name: max-size
Long-form Attribute Name: Maximum message size. Long-form Attribute Name: Maximum message size.
Type: Media level Type: Media level
Subject to Charset Attribute: No Subject to Charset Attribute: No
Purpose and Appropriate Values: The "max-size" attribute indicates Purpose and Appropriate Values: The "max-size" attribute indicates
the largest message an endpoint wishes to accept. It may take any the largest message an endpoint wishes to accept. It may take any
numeric value, specified in octets. numeric value, specified in octets.
15.4.4 Path 15.7.4 Path
Contact Information: Ben Campbell (ben@estacado.net) Contact Information: Ben Campbell (ben@estacado.net)
Attribute-name: path Attribute-name: path
Long-form Attribute Name: MSRP URL Path Long-form Attribute Name: MSRP URL Path
Type: Media level Type: Media level
Subject to Charset Attribute: No Subject to Charset Attribute: No
Purpose and Appropriate Values: The "path" attribute indicates a Purpose and Appropriate Values: The "path" attribute indicates a
series of MSRP devices that must be visited by messages sent in series of MSRP devices that must be visited by messages sent in
the session, including the final endpoint. The attribute contains the session, including the final endpoint. The attribute contains
one or more MSRP URIs, delimited by the space character. one or more MSRP URIs, delimited by the space character.
16. Change History 16. Contributors and Acknowledgments
16.1 draft-ietf-simple-message-sessions-10
Changed SDP m-line protocol field to "msrp/tcp". Added
requirement to copy the MSRP address and port from the path to the
c and m lines as a courtesy to legacy SDP devices. The path
attribute is still used as previousl specificed.
Changed SDP reference to point to SDP-New draft.
Relaxed the URL session-id syntax to allow (unreserved / "+" / "="
/ "/" ), to make it easier to embed base64 encoded information.
Updated example in overview to have Byte-Range header.
Added 413 response code.
Changed report-failure and report-success to failure-report and
success-report, respectively. Change made to increase parsing
efficiency.
Refined the iana registration section.
Added registration of "msrp" as an sdp proto field value in iana
section.
Moved 408 and 423 from relays document to this draft.
Expanded security considerations to include more discussion of the
difficulties of peer-to-peer TLS, and how relays can help make
that better.
16.2 draft-ietf-simple-message-sessions-09
o Updated retransmission when receiving a failure report.
o Added applicability statement.
o Added CPIM application considerations.
o Added language to security considerations about receiving messages
from the same sender over different sessions.
o Added 501 response code.
o Various scrubbing of the ABNF
o Change resource construction name to session-id in MSRP syntax.
o Added language to define the purpose of msrp URLs.
o Change RFC2396 reference to 2396bis
o Clarify that max-size is in octets.
o Clarify that userinfo is restricted to unreserved characters,
which is an additional restriction over the RFC2396 version.
o Consolidated the ABNF for the MSRP URL into the formal syntax
section.
o Clarified that if an MSRP endpoint receives and SDP offer and does
not understand any of the media types, it SHOULD return a SIP 488
response, or whatever is appropriate for the rendezvous protocol.
o Added more text around using message/cpim for identity
attribution.
16.3 draft-ietf-simple-message-sessions-08
o Removed DSN section. Removed statements that an error report
SHOULD contain a body. REPORT requests may now contain
informational bodies no larger than 2K, but the recipient is free
to ignore them.
o Added the "#" value for the continuation-flag to indicate the last
chunk of an abandoned message.
o Added direction that s/mime and cpim envelops must be applied
before chunking.
o Added direction to set the last-byte field in byte-range to "*" if
there is any chance of interrupting a SEND request.
o Changed to refer to entire message, instead of a particular MIME
content-type
o Added requirement for the use of UTF-8, and reference to RFC3629
o Added requirement to ignore unknown headers.
o Several ABNF fixes
o Removed redundant material between normative sections.
o Numerous editorial fixes.
16.4 draft-ietf-simple-message-sessions-07
o Significant re-write to attempt to improve readability.
o Added maximum size parameter in accept-types
o Changed the Boundary field to be part of the start-line rather
than a header field.
o Removed the TR-ID header, and changed request-response matching to
be based on the Boundary field value. Responses still contain the
TR-ID header, which must match the Boundary from the request.
o Removed transport selection from URL scheme and added the "tcp"
parameter.
o Added description of the "simple" mode with no transaction
responses, and made mode selection dependent on the reporting
level requested for a give message.
o Changed the DSN section to reflect separate request of success and
failure reports. Enhanced REPORT method to be useful even without
a payload.
o removed SRV usage for URL resolution. This is only used for relay
discovery, and therefore should be moved to the relay draft.
o Added discussion about late REPORT handling. Asserted that REPORT
requests are always sent in simple mode.
o Removed the dependency on multipart/byteranges for fragmentation.
Incorporated the Byte-Range header into the base MSRP header set.
o Removed the VISIT method. Change to use SEND to serve the purpose
formerly reserved to VISIT.
16.5 draft-ietf-simple-message-sessions-06
o Changed To and From header names to To-Path and From-Path. Added
more clarification to path handling, and commentary on how it
enables relay usage.
o Changed mechanism for signaling transport and TLS protection into
the MSRP URL, rather than the SDP M-Line.
o Removed length field from start line and added Boundary header
field and Closing field.
o Added recommendation to fragment any content over 2k.
o Added Rohan's proposal to make offerer connect to answerer. (With
open issue for more discussion.)
o Changed To-Path and From-Path usage in responses to indicate the
destination and source of the response, rather than merely copy
from the associated request.
o Updated DSN section. Added text on field usage.
o Fixed change TR-ID header from version 05 were erroneously
attributed to 04.
16.6 draft-ietf-simple-message-sessions-05
o Changed the use of session URLs. Instead of a single session URL,
each endpoint is identified by a distinct URL. MSRP requests will
put the destination URL in a To header, and the sender URL in a
From header.
o Changed the SDP exchange of MSRP URLs to handle the URL for each
endpoint. Further, changed the SDP attribute to support a list of
URLs in each direction. This may be used with relays to exchange
paths, rather than single URLs. MSRP endpoints must be able to
intelligently process such a list if received. This document does
not, however, describe how to generate such a list.
o Added section for Delivery Status Notification handling, and added
associated entries into the syntax definition.
o Added content fragmentation section.
o Removed recommendation to start separate session for large
transfers.
o Corrected some mistakes in the syntax definitions.
o Added Chris Boulton as a co-author for his contribution of the DSN
text.
16.7 draft-ietf-simple-message-sessions-04
o Removed the direction attribute. Rather than using a comedia
styled direction negotiation, we just state that the answerer
opens any needed connection.
16.8 draft-ietf-simple-message-sessions-03
o Removed all specification of relays, and all features specific to
the use of relays. The working group has chosen to move relay
work into a separate effort, in order to advance the base
specification. (The MSRP acronym is unchanged for the sake of
convenience.) This included removal of the BIND method, all
response codes specific to BIND, Digest Authentication, and the
inactivity timeout.
o Removed text indicating that an endpoint could retry failed
requests on the same connection. Rather, the endpoint should
consider the connection dead, and either signal a reconnection or
end the session.
o Added text describing subsequent SDP exchanges. Added mandatory
"count" parameter to the direction attribute to allow explicit
signaling of the need to reconnect.
o Added text to describe the use of send and receive only indicators
in SDP for one-way transfer of large content.
o Added text requiring unique port field values if multiple M-line's
exist.
o Corrected a number of editorial mistakes.
16.9 draft-ietf-simple-message-sessions-02
o Moved all content type negotiation from the "m"-line format list
into "a"-line attributes. Added the accept-types attribute. This
is due to the fact that the sdp format-list syntax is not
conducive to encoding MIME content types values.
o Added "other-method" construction to the message syntax to allow
for extensible methods.
o Consolidated all syntax definitions into the same section.
Cleaned up ABNF for digest challenge and response syntax.
o Changed the session inactivity timeout to 12 minutes.
o Required support for the SHA1 algorithm.
o Required support for the message/cpim format.
o Fixed lots of editorial issues.
o Documented a number of open issues from recent list discussions.
16.10 draft-ietf-simple-message-sessions-01
o Abstract rewritten.
o Added architectural considerations section.
o The m-line format list now only describes the root body part for a
request. Contained body part types may be described in the
"accept-wrapped-types" a-line attribute.
o Added a standard dummy value for the m-line port field. Clarified
that a zero in this field has normal SDP meaning.
o Clarified that an endpoint is globally configured as to whether or
not to use a relay. There is no relay discovery mechanism
intrinsic to MSRP.
o Changed digest algorithm to SHA1. Added TR-ID and S-URI to the
hash for digest authentication.
o CMS usage replaced with S/MIME.
o TLS and msrps: usage clarified.
o Session state timeout is now based on SEND activity, rather than
BIND and VISIT refreshes.
o Default port added.
o Added sequence diagrams to the example message flows.
o Added discussion of self-signed certificates in the security
considerations section.
16.11 draft-ietf-simple-message-sessions-00
o Name changed to reflect status as a work group item.
o This version no longer supports the use of multiple sessions
across a single TCP session. This has several related changes:
There is now a single session URL, rather than a separate one for
each endpoint. The session URL is not required to be in requests
other than BIND and VISIT, as the session can be determined based
on the connection on which it arrives.
o BIND and VISIT now create soft state, eliminating the need for the
RELEASE and LEAVE methods.
o The MSRP URL format was changed to better reflect generic URL
standards. URL comparison and resolution rules were added. SRV
usage added.
o Determination of host and visitor roles now uses a direction
attribute much like the one used in COMEDIA.
o Format list negotiation expanded to allow a "prefer these formats
but try anything" semantic
o Clarified handling of direction notification failures.
o Clarified signaling associated with session failure due to dropped
connections.
o Clarified security related motivations for MSRP.
o Removed MIKEY dependency for session key exchange. Simple usage
of k-lines in SDP, where the SDP exchange is protected end-to-end
seems sufficient.
16.12 draft-campbell-simple-im-sessions-01
Version 01 is a significant re-write. References to COMEDIA were
removed, as it was determined that COMEDIA would not allow
connections to be used bidirectional in the presence of NATs.
Significantly more discussion of a concrete mechanism has been added
to make up for no longer using COMEDIA. Additionally, this draft and
draft-campbell-cpimmsg-sessions (which would have also changed
drastically) have now been combined into this single draft.
17. Contributors and Acknowledgments
In addition to the editors, The following people contributed In addition to the editors, the following people contributed
extensive work to this document: Chris Boulton, Paul Kyzivat, Orit extensive work to this document: Chris Boulton, Paul Kyzivat, Orit
Levin, Adam Roach, Jonathan Rosenberg, and Robert Sparks. Levin, Adam Roach, Jonathan Rosenberg, and Robert Sparks.
The following people contributed substantial discussion and feedback The following people contributed substantial discussion and feedback
to this ongoing effort: Eric Burger, Allison Mankin, Jon Peterson, to this ongoing effort: Eric Burger, Allison Mankin, Jon Peterson,
Brian Rosen, Dean Willis, Aki Niemi, Hisham Khartabil, Pekka Pessi, Brian Rosen, Dean Willis, Aki Niemi, Hisham Khartabil, Pekka Pessi,
Miguel Garcia, Peter Ridler, and Sam Hartman. Miguel Garcia, Peter Ridler, and Sam Hartman.
18. References 17. References
18.1 Normative References 17.1 Normative References
[1] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0", [1] Dierks, T. and C. Allen, "The TLS Protocol Version 1.0",
RFC 2246, January 1999. RFC 2246, January 1999.
[2] Handley, M., Jacobson, V. and C. Perkins, "SDP: Session [2] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", Description Protocol", draft-ietf-mmusic-sdp-new-23 (work in
Internet-Draft draft-ietf-mmusic-sdp-new-23, December 2004. progress), December 2004.
[3] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with [3] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with
Session Description Protocol (SDP)", RFC 3264, June 2002. Session Description Protocol (SDP)", RFC 3264, June 2002.
[4] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., [4] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
Peterson, J., Sparks, R., Handley, M. and E. Schooler, "SIP: Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP:
Session Initiation Protocol", RFC 3261, June 2002. Session Initiation Protocol", RFC 3261, June 2002.
[5] Bradner, S., "Key words for use in RFCs to Indicate Requirement [5] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
[6] Crocker, D. and P. Overell, "Augmented BNF for Syntax [6] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, November 1997. Specifications: ABNF", RFC 2234, November 1997.
[7] Freed, N. and N. Borenstein, "Multipurpose Internet Mail [7] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part One: Format of Internet Message Bodies", Extensions (MIME) Part One: Format of Internet Message Bodies",
RFC 2045, November 1996. RFC 2045, November 1996.
[8] Troost, R., Dorner, S. and K. Moore, "Communicating [8] Troost, R., Dorner, S., and K. Moore, "Communicating
Presentation Information in Internet Messages: The Presentation Information in Internet Messages: The Content-
Content-Disposition Header Field", RFC 2183, August 1997. Disposition Header Field", RFC 2183, August 1997.
[9] Berners-Lee, T., Fielding, R. and L. Masinter, "Uniform [9] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifiers (URI): Generic Syntax", Resource Identifiers (URI): Generic Syntax", rfc 3986,
internet-draft draft-fielding-uri-rfc2396bis-07, September January 2005.
2004.
[10] Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J. and [10] Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J., and
T. Wright, "Transport Layer Security (TLS) Extensions", T. Wright, "Transport Layer Security (TLS) Extensions",
RFC 3546, June 2003. RFC 3546, June 2003.
[11] Rosenberg, J., "The Session Initiation Protocol (SIP) UPDATE [11] Rosenberg, J., "The Session Initiation Protocol (SIP) UPDATE
Method", RFC 3311, October 2002. Method", RFC 3311, October 2002.
[12] Klyne, G. and D. Atkins, "Common Presence and Instant Messaging [12] Klyne, G. and D. Atkins, "Common Presence and Instant Messaging
(CPIM): Message Format", RFC 3862, August 2004. (CPIM): Message Format", RFC 3862, August 2004.
[13] Chown, P., "Advanced Encryption Standard (AES) Ciphersuites for [13] Chown, P., "Advanced Encryption Standard (AES) Ciphersuites for
Transport Layer Secur ity (TLS)", RFC 3268, June 2002. Transport Layer Secur ity (TLS)", RFC 3268, June 2002.
[14] Yergeau, F., "UTF-8, a transformation format of ISO 10646", [14] Yergeau, F., "UTF-8, a transformation format of ISO 10646",
RFC 3629, November 2003. RFC 3629, November 2003.
18.2 Informational References [15] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types", rfc 2046,
November 1996.
[15] Johnston, A. and O. Levin, "Session Initiation Protocol Call 17.2 Informational References
[16] Johnston, A. and O. Levin, "Session Initiation Protocol Call
Control - Conferencing for User Agents", Control - Conferencing for User Agents",
Internet-Draft draft-ietf-sipping-cc-conferencing-05, October draft-ietf-sipping-cc-conferencing-05 (work in progress),
2004. October 2004.
[16] Rosenberg, J., Peterson, J., Schulzrinne, H. and G. Camarillo, [17] Rosenberg, J., Peterson, J., Schulzrinne, H., and G. Camarillo,
"Best Current Practices for Third Party Call Control in the "Best Current Practices for Third Party Call Control in the
Session Initiation Protocol", rfc 3725, April 2004. Session Initiation Protocol", rfc 3725, April 2004.
[17] Sparks, R. and A. Johnston, "Session Initiation Protocol Call [18] Sparks, R. and A. Johnston, "Session Initiation Protocol Call
Control - Transfer", Control - Transfer", draft-ietf-sipping-cc-transfer-03 (work in
Internet-Draft draft-ietf-sipping-cc-transfer-03, October 2004. progress), October 2004.
[18] Campbell, B., Rosenberg, J., Schulzrinne, H., Huitema, C. and [19] Campbell, B., Rosenberg, J., Schulzrinne, H., Huitema, C., and
D. Gurle, "Session Initiation Protocol (SIP) Extension for D. Gurle, "Session Initiation Protocol (SIP) Extension for
Instant Messaging", RFC 3428, December 2002. Instant Messaging", RFC 3428, December 2002.
[19] Mahy, R., "Benefits and Motivation for Session Mode Instant [20] Mahy, R., "Benefits and Motivation for Session Mode Instant
Messaging", Messaging", draft-mahy-simple-why-session-mode-01 (work in
Internet-Draft draft-mahy-simple-why-session-mode-01, February progress), February 2004.
2004.
[20] Jennings, C. and R. Mahy, "Relay Extensions for Message [21] Jennings, C. and R. Mahy, "Relay Extensions for Message
Sessions Relay Protocol (MSRP)", Sessions Relay Protocol (MSRP)",
Internet-Draft draft-ietf-simple-msrp-relays-03, February 2005. draft-ietf-simple-msrp-relays-05 (work in progress), July 2005.
[21] Peterson, J. and C. Jennings, "Enhancements for Authenticated [22] Peterson, J. and C. Jennings, "Enhancements for Authenticated
Identity Management in the Session Initiation Protocol (SIP)", Identity Management in the Session Initiation Protocol (SIP)",
Internet-Draft draft-ietf-sip-identity-03 , September 2004. draft-ietf-sip-identity-03 (work in progress), September 2004.
[22] Jennings, C. and J. Peterson, "Certificate Management Service [23] Jennings, C. and J. Peterson, "Certificate Management Service
for SIP", Internet-Draft draft-ietf-sipping-certs-00, October for SIP", draft-ietf-sipping-certs-00 (work in progress),
2004. October 2004.
[23] Yon, D., "Connection-Oriented Media Transport in SDP", [24] Yon, D., "Connection-Oriented Media Transport in SDP",
Internet-Draft draft-ietf-mmusic-sdp-comedia-09, September draft-ietf-mmusic-sdp-comedia-09 (work in progress),
2004. September 2004.
[24] Peterson, J., "A Common Profile for Instant Messaging (CPIM)", [25] Peterson, J., "A Common Profile for Instant Messaging (CPIM)",
rfc 3860, August 2004. rfc 3860, August 2004.
[25] Housley, R., "Triple-DES and RC2 Key Wrapping", RFC 3217, [26] Housley, R., "Triple-DES and RC2 Key Wrapping", RFC 3217,
December 2001. December 2001.
[26] Ramsdell, B., "S/MIME Version 3 Message Specification", [27] Ramsdell, B., "S/MIME Version 3 Message Specification",
RFC 2633, June 1999. RFC 2633, June 1999.
[27] Camarillo, G. and H. Schulzrinne, "Early Media and Ringing Tone [28] Camarillo, G. and H. Schulzrinne, "Early Media and Ringing Tone
Generation in the Session Initiation Protocol (SIP)", Generation in the Session Initiation Protocol (SIP)",
Internet-Draft draft-ietf-sipping-early-media-02, June 2004. draft-ietf-sipping-early-media-02 (work in progress),
June 2004.
[28] Saint-Andre, P., "Extensible Messaging and Presence Protocol [29] Saint-Andre, P., "Extensible Messaging and Presence Protocol
(XMPP): Instant Messaging and Presence", rfc 3921, October (XMPP): Instant Messaging and Presence", rfc 3921,
2004. October 2004.
[29] Rosenberg, J., "Indicating User Agent Capabilities in the [30] Rosenberg, J., "Indicating User Agent Capabilities in the
Session Initiation Protocol (SIP)", rfc 3840, August 2004. Session Initiation Protocol (SIP)", rfc 3840, August 2004.
[31] Peterson, J., "Address Resolution for Instant Messaging and
Presence", rfc 3861, August 2004.
Authors' Addresses Authors' Addresses
Ben Campbell (editor) Ben Campbell (editor)
Estacado Systems Estacado Systems
17210 Campbell Road
Suite 250
Dallas, TX 75252
USA
Email: ben@estacado.net Email: ben@estacado.net
Rohan Mahy (editor) Rohan Mahy (editor)
Airespace blankespace
110 Nortech Parkway
San Jose, CA 95134
USA
Email: rohan@ekabal.com Email: rohan@ekabal.com
Cullen Jennings (editor) Cullen Jennings (editor)
Cisco Systems, Inc. Cisco Systems, Inc.
170 West Tasman Dr. 170 West Tasman Dr.
MS: SJC-21/2 MS: SJC-21/2
San Jose, CA 95134 San Jose, CA 95134
USA USA
 End of changes. 

This html diff was produced by rfcdiff 1.25, available from http://www.levkowetz.com/ietf/tools/rfcdiff/