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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) -- Possible downref: Non-RFC (?) normative reference: ref. 'XEP-0071' == Outdated reference: A later version (-11) exists of draft-ietf-stox-chat-10 == Outdated reference: A later version (-11) exists of draft-ietf-stox-groupchat-10 Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group P. Saint-Andre 3 Internet-Draft &yet 4 Intended status: Standards Track A. Houri 5 Expires: August 17, 2015 IBM 6 J. Hildebrand 7 Cisco Systems, Inc. 8 February 13, 2015 10 Interworking between the Session Initiation Protocol (SIP) and the 11 Extensible Messaging and Presence Protocol (XMPP): Instant Messaging 12 draft-ietf-stox-im-12 14 Abstract 16 This document defines a bidirectional protocol mapping for the 17 exchange of single instant messages between the Session Initiation 18 Protocol (SIP) and the Extensible Messaging and Presence Protocol 19 (XMPP). 21 Status of This Memo 23 This Internet-Draft is submitted in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF). Note that other groups may also distribute 28 working documents as Internet-Drafts. The list of current Internet- 29 Drafts is at http://datatracker.ietf.org/drafts/current/. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 This Internet-Draft will expire on August 17, 2015. 38 Copyright Notice 40 Copyright (c) 2015 IETF Trust and the persons identified as the 41 document authors. All rights reserved. 43 This document is subject to BCP 78 and the IETF Trust's Legal 44 Provisions Relating to IETF Documents 45 (http://trustee.ietf.org/license-info) in effect on the date of 46 publication of this document. Please review these documents 47 carefully, as they describe your rights and restrictions with respect 48 to this document. Code Components extracted from this document must 49 include Simplified BSD License text as described in Section 4.e of 50 the Trust Legal Provisions and are provided without warranty as 51 described in the Simplified BSD License. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 56 2. Intended Audience . . . . . . . . . . . . . . . . . . . . . . 3 57 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 58 4. XMPP to SIP . . . . . . . . . . . . . . . . . . . . . . . . . 4 59 5. SIP to XMPP . . . . . . . . . . . . . . . . . . . . . . . . . 6 60 6. Message Size . . . . . . . . . . . . . . . . . . . . . . . . 8 61 7. Content Types . . . . . . . . . . . . . . . . . . . . . . . . 8 62 8. Internationalization Considerations . . . . . . . . . . . . . 8 63 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 64 10. Security Considerations . . . . . . . . . . . . . . . . . . . 9 65 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 66 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 11 67 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 69 1. Introduction 71 In order to help ensure interworking between instant messaging (IM) 72 systems that conform to the instant messaging / presence requirements 73 [RFC2779], it is important to clearly define protocol mappings 74 between such systems. Within the IETF, work has proceeded on two 75 instant messaging technologies: 77 o Various extensions to the Session Initiation Protocol ([RFC3261]) 78 for instant messaging, in particular the MESSAGE method extension 79 [RFC3428]. 81 o The Extensible Messaging and Presence Protocol (XMPP), which 82 consists of a formalization of the core XML streaming protocols 83 developed originally by the Jabber open-source community; the 84 relevant specifications are [RFC6120] for the XML streaming layer 85 and [RFC6121] for basic presence and instant messaging extensions. 87 One approach to helping ensure interworking between these protocols 88 is to map each protocol to the abstract semantics described in 89 [RFC3860]; that is the approach taken by 90 [I-D.ietf-simple-cpim-mapping] and [RFC3922]. By contrast, the 91 approach taken in this document is to directly map semantics from one 92 protocol to another (i.e., from SIP/SIMPLE to XMPP and vice-versa), 93 since that is how existing systems solve the interworking problem. 95 Both XMPP and IM-capable SIP systems enable entities to exchange 96 "instant messages". The term "instant message" usually refers to a 97 message sent between two entities for delivery in close to real time 98 (rather than a message that is stored and forwarded to the intended 99 recipient upon request). This document covers single messages only 100 (sometimes called "pager-mode" messaging), since they form the lowest 101 common denominator for IM. Separate documents cover one-to-one chat 102 sessions [I-D.ietf-stox-chat] and multi-party groupchat 103 [I-D.ietf-stox-groupchat]. 105 The architectural assumptions underlying such direct mappings are 106 provided in [RFC7247], including mapping of addresses and error 107 conditions. The mappings specified in this document cover basic 108 instant messaging functionality, i.e., the exchange of a single 109 instant message between a SIP user and an XMPP user in either 110 direction. Mapping of more advanced functionality is out of scope 111 for this document, but other documents in this "series" cover such 112 topics. 114 2. Intended Audience 116 The documents in this series are intended for use by software 117 developers who have an existing system based on one of these 118 technologies (e.g., SIP), and would like to enable communication from 119 that existing system to systems based on the other technology (e.g., 120 XMPP). We assume that readers are familiar with the core 121 specifications for both SIP [RFC3261] and XMPP [RFC6120], with the 122 base document for this series [RFC7247], and with the following IM- 123 related specifications: 125 o Session Initiation Protocol (SIP) Extension for Instant Messaging 126 [RFC3428] 128 o Extensible Messaging and Presence Protocol: Instant Messaging and 129 Presence [RFC6121] 131 Note well that not all protocol-compliant messages are shown (such as 132 SIP 100 TRYING messages), in order to focus the reader on the 133 essential aspects of the protocol flows. 135 3. Terminology 137 A number of terms used here are explained in [RFC3261], [RFC3428], 138 [RFC6120], and [RFC6121]. 140 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 141 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 142 "OPTIONAL" in this document are to be interpreted as described in 143 [RFC2119]. 145 4. XMPP to SIP 147 As described in [RFC6121], a single instant message is an XML 148 stanza of type "normal" sent over an XML stream (since 149 "normal" is the default for the 'type' attribute of the 150 stanza, the attribute is often omitted). 152 When the XMPP user Juliet wants to send an 153 instant message to Romeo, she interacts with her XMPP client, which 154 generates an XMPP stanza. The syntax of the 155 stanza, including required and optional elements and attributes, is 156 defined in [RFC6121] (for single instant messages, the value of the 157 'to' address SHOULD be a "bare JID" of the form 158 "localpart@domainpart", as per [RFC6121]). The following is an 159 example of such a stanza: 161 Example 1: XMPP user sends message 163 | 165 | Art thou not Romeo, and a Montague? 166 | 168 Upon receiving such a message stanza, the XMPP server needs to 169 determine the identity of the domainpart in the 'to' address, which 170 it does by following the procedures explained in Section 5 of 171 [RFC7247]. If the domain is a SIP domain, the XMPP server will hand 172 off the message stanza to an XMPP-to-SIP gateway that natively 173 communicates with IM-aware SIP servers. 175 The XMPP-to-SIP gateway is then responsible for translating the XMPP 176 message stanza into a SIP MESSAGE request from the XMPP user to the 177 SIP user: 179 Example 2: XMPP user sends message (SIP transformation) 181 | MESSAGE sip:romeo@example.net SIP/2.0 182 | Via: SIP/2.0/TCP x2s.example.com;branch=z9hG4bK776sgdkse 183 | Max-Forwards: 70 184 | To: sip:romeo@example.net 185 | From: ;tag=12345 186 | Call-ID: D9AA95FD-2BD5-46E2-AF0F-6CFAA96BDDFA 187 | CSeq: 1 MESSAGE 188 | Content-Type: text/plain 189 | Content-Length: 35 190 | 191 | Art thou not Romeo, and a Montague? 192 The destination SIP server is responsible for delivering the message 193 to the intended recipient, and the recipient is responsible for 194 generating a response (e.g., 200 OK). 196 Example 3: SIP user agent indicates receipt of message 198 | SIP/2.0 200 OK 199 | Via: SIP/2.0/TCP x2s.example.com;branch=z9hG4bK776sgdkse 200 | From: sip:juliet@example.com;tag=12345 201 | To: sip:romeo@example.net;tag=vwxyz 202 | Call-ID: D9AA95FD-2BD5-46E2-AF0F-6CFAA96BDDFA 203 | CSeq: 1 MESSAGE 204 | Content-Length: 0 206 As described in [RFC3428], a downstream proxy could fork a MESSAGE 207 request, but it would return only one 200 OK to the gateway. 209 Note: This document does not specify handling of the 200 OK by the 210 XMPP-to-SIP gateway (e.g., to enable message acknowledgements). 211 See [I-D.ietf-stox-chat] for a mapping of message acknowledgements 212 in the context of one-to-one chat sessions. 214 The mapping of XMPP syntax to SIP syntax MUST be as shown in the 215 following table. 217 Table 1: Message syntax mapping from XMPP to SIP 219 +-----------------------------+--------------------------+ 220 | XMPP Element or Attribute | SIP Header or Contents | 221 +-----------------------------+--------------------------+ 222 | | body of MESSAGE | 223 | | Subject | 224 | | Call-ID | 225 | from | From (1) | 226 | id | transaction identifer | 227 | to | To or Request-URI | 228 | type | (no mapping) (2) | 229 | xml:lang | Content-Language | 230 +-----------------------------+--------------------------+ 232 1. As shown in the foregoing example and described in [RFC7247], the 233 XMPP-to-SIP gateway MUST map the bare JID 234 ("localpart@domainpart") of the XMPP sender to the SIP From 235 header and include the resourcepart of the full JID as the GRUU 236 portion [RFC5627] of the SIP URI. 238 2. Because there is no SIP header field that matches the meaning of 239 the XMPP message 'type' values ("normal", "chat", "groupchat", 240 "headline", "error"), no general mapping is possible here. 242 5. SIP to XMPP 244 As described in [RFC3428], a single instant message is a SIP MESSAGE 245 request sent from a SIP user agent to an intended recipient who is 246 most generally referenced by an Instant Message URI of the form 247 but who might be referenced by a SIP or SIPS URI of 248 the form or . 250 When the SIP user Romeo wants to send an 251 instant message to Juliet, he interacts with his SIP user agent, 252 which generates a SIP MESSAGE request. The syntax of the MESSAGE 253 request is defined in [RFC3428]. The following is an example of such 254 a request: 256 Example 4: SIP user sends message 258 | MESSAGE sip:juliet@example.com SIP/2.0 259 | Via: SIP/2.0/TCP s2x.example.net;branch=z9hG4bKeskdgs677 260 | Max-Forwards: 70 261 | To: sip:juliet@example.com 262 | From: sip:romeo@example.net;tag=vwxyz 263 | Call-ID: 9E97FB43-85F4-4A00-8751-1124FD4C7B2E 264 | CSeq: 1 MESSAGE 265 | Content-Type: text/plain 266 | Content-Length: 44 267 | 268 | Neither, fair saint, if either thee dislike. 270 Section 5 of [RFC3428] stipulates that a SIP User Agent presented 271 with an im: URI should resolve it to a sip: or sips: URI. Therefore 272 we assume that the Request-URI of a request received by an IM-capable 273 SIP-to-XMPP gateway will contain a sip: or sips: URI. Upon receiving 274 the MESSAGE, the SIP server needs to determine the identity of the 275 domain portion of the Request-URI or To header, which it does by 276 following the procedures explained in Section 5 of [RFC7247]. If the 277 domain is an XMPP domain, the SIP server will hand off the MESSAGE to 278 an associated SIP-to-XMPP gateway that natively communicates with 279 XMPP servers. 281 The SIP-to-XMPP gateway is then responsible for translating the 282 request into an XMPP message stanza from the SIP user to the XMPP 283 user and returning a SIP "200 OK" message to the sender: 285 Example 5: SIP user sends message (XMPP transformation) 287 | 289 | Neither, fair saint, if either thee dislike. 290 | 292 Note that the stanza handling rules specified in [RFC6121] allow the 293 receiving XMPP server to deliver a message stanza whose 'to' address 294 is a bare JID ("localpart@domainpart") to multiple connected devices. 295 This is similar to the "forking" of messages in SIP. 297 The mapping of SIP syntax to XMPP syntax MUST be as shown in the 298 following table. 300 Table 2: Message syntax mapping from SIP to XMPP 302 +--------------------------+-----------------------------+ 303 | SIP Header or Contents | XMPP Element or Attribute | 304 +--------------------------+-----------------------------+ 305 | Call-ID | | 306 | Content-Language | xml:lang | 307 | CSeq | (no mapping) | 308 | From | from (1) | 309 | Subject | | 310 | Request-URI or To | to | 311 | body of MESSAGE | | 312 | transaction identifier | id | 313 +--------------------------+-----------------------------+ 315 1. As shown in the foregoing example and described in [RFC7247], if 316 the IM-capable SIP-to-XMPP gateway has information about the GRUU 317 [RFC5627] of the particular endpoint that sent the SIP message 318 then it MUST map the sender's address to a full JID 319 ("localpart@domainpart/resourcepart") in the 'from' attribute of 320 the XMPP stanza and include the GRUU as the resourcepart. 322 When transforming SIP pager-mode messages, an IM-capable SIP-to-XMPP 323 gateway MUST specify no XMPP 'type' attribute or, equivalently, a 324 'type' attribute whose value is "normal" [RFC6121]. 326 See Section 7 of this document about the handling of SIP message 327 bodies that contain content types other than plain text. 329 6. Message Size 331 [RFC3428] specifies that (outside of a media session) the size of a 332 MESSAGE request is not allowed to exceed 1300 bytes. Although in 333 practice XMPP instant messages do not often exceed that size, neither 334 [RFC6120] nor [RFC6121] sets an upper limit on the size of XMPP 335 stanzas. However, XMPP server deployments usually do limit the size 336 of stanzas in order to help prevent denial of service attacks, and 337 [RFC6120] states that if a server sets a maximum stanza size then the 338 limit is not allowed to be less than 10,000 bytes. Because of this 339 mismatch, an XMPP-to-SIP gateway SHOULD return a 340 stanza error if an XMPP user attempts to send an XMPP message stanza 341 that would result in a SIP MESSAGE greater than 1300 bytes. Although 342 such a gateway might decide to "upgrade" from page mode to session 343 mode using the Message Session Relay Protocol (MSRP) and thus 344 treating the instant message as part of a chat session as described 345 in [I-D.ietf-stox-chat], such behavior is application-specific and 346 this document provides no guidelines for how to complete such an 347 upgrade. 349 7. Content Types 351 SIP requests of type MESSAGE are allowed to contain essentially any 352 content type. The recommended procedures for SIP-to-XMPP gateways to 353 use in handling these content types are as follows. 355 An IM-aware SIP-to-XMPP gateway MUST process SIP messages that 356 contain message bodies of type "text/plain" and MUST encapsulate such 357 message bodies as the XML character data of the XMPP element. 359 An IM-aware SIP-to-XMPP gateway SHOULD process SIP messages that 360 contain message bodies of type "text/html"; if so, a gateway MUST 361 transform the "text/html" content into XHTML content that conforms to 362 the XHTML-IM Integration Set specified in [XEP-0071]. 364 Although an IM-aware SIP-to-XMPP gateway MAY process SIP messages 365 that contain message bodies of types other than "text/plain" and 366 "text/html", the handling of such content types is a matter of 367 implementation. 369 8. Internationalization Considerations 371 Both XMPP and SIP support the UTF-8 encoding [RFC3629] of Unicode 372 characters [UNICODE] within messages, and signalling of the language 373 for a particular message (in XMPP via the 'xml:lang' attribute and in 374 SIP via the Content-Language header). Several examples follow, using 375 the "XML Notation" [RFC3987] for Unicode characters outside the ASCII 376 range. 378 Example 6: SIP user sends message 380 | MESSAGE sip:juliet@example.com SIP/2.0 381 | Via: SIP/2.0/TCP s2x.example.net;branch=z9hG4bKeskdgs677 382 | Max-Forwards: 70 383 | To: sip:juliet@example.com 384 | From: sip:romeo@example.net;tag=vwxyz 385 | Call-ID: 5A37A65D-304B-470A-B718-3F3E6770ACAF 386 | CSeq: 1 MESSAGE 387 | Content-Type: text/plain 388 | Content-Length: 45 389 | Content-Language: cs 390 | 391 | Nic z ob쎩ho, m쎡 d쒛vo spanil쎡, 392 | nenavid쎭얡-li jedno nebo druh쎩. 394 Example 7: SIP user sends message (XMPP transformation) 396 | 399 | 400 | Nic z ob쎩ho, m쎡 d쒛vo spanil쎡, 401 | nenavid쎭얡-li jedno nebo druh쎩. 402 | 403 | 405 9. IANA Considerations 407 This document requests no actions of IANA. 409 10. Security Considerations 411 Detailed security considerations for instant messaging protocols are 412 given in [RFC2779], for SIP-based instant messaging in [RFC3428] (see 413 also [RFC3261]), and for XMPP-based instant messaging in [RFC6121] 414 (see also [RFC6120]). The security considerations provided in 415 [RFC7247] also apply. 417 This document specifies methods for exchanging instant messages 418 through a gateway that translates between SIP and XMPP. Such a 419 gateway MUST be compliant with the minimum security requirements of 420 the instant messaging protocols for which it translates (i.e., SIP 421 and XMPP). The addition of gateways to the security model of instant 422 messaging specified in [RFC2779] introduces some new risks. In 423 particular, end-to-end security properties (especially 424 confidentiality and integrity) between instant messaging user agents 425 that interface through an IM-capable SIP-to-XMPP gateway can be 426 provided only if common formats are supported. Although 427 specification of those common formats is out of scope for this 428 document, for instant messages it is possible to use [RFC3862] (see 429 also [RFC3923]). 431 11. References 433 11.1. Normative References 435 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 436 Requirement Levels", BCP 14, RFC 2119, March 1997. 438 [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, 439 A., Peterson, J., Sparks, R., Handley, M., and E. 440 Schooler, "SIP: Session Initiation Protocol", RFC 3261, 441 June 2002. 443 [RFC3428] Campbell, B., Rosenberg, J., Schulzrinne, H., Huitema, C., 444 and D. Gurle, "Session Initiation Protocol (SIP) Extension 445 for Instant Messaging", RFC 3428, December 2002. 447 [RFC5627] Rosenberg, J., "Obtaining and Using Globally Routable User 448 Agent URIs (GRUUs) in the Session Initiation Protocol 449 (SIP)", RFC 5627, October 2009. 451 [RFC6120] Saint-Andre, P., "Extensible Messaging and Presence 452 Protocol (XMPP): Core", RFC 6120, March 2011. 454 [RFC6121] Saint-Andre, P., "Extensible Messaging and Presence 455 Protocol (XMPP): Instant Messaging and Presence", RFC 456 6121, March 2011. 458 [RFC7247] Saint-Andre, P., Houri, A., and J. Hildebrand, 459 "Interworking between the Session Initiation Protocol 460 (SIP) and the Extensible Messaging and Presence Protocol 461 (XMPP): Architecture, Addresses, and Error Handling", RFC 462 7247, May 2014. 464 [XEP-0071] 465 Saint-Andre, P., "XHTML-IM", XSF XEP 0071, November 2012. 467 11.2. Informative References 469 [I-D.ietf-simple-cpim-mapping] 470 Rosenberg, J. and B. Campbell, "CPIM Mapping of SIMPLE 471 Presence and Instant Messaging", draft-ietf-simple-cpim- 472 mapping-01 (work in progress), June 2002. 474 [I-D.ietf-stox-chat] 475 Saint-Andre, P. and S. Loreto, "Interworking between the 476 Session Initiation Protocol (SIP) and the Extensible 477 Messaging and Presence Protocol (XMPP): One-to-One Text 478 Chat Sessions", draft-ietf-stox-chat-10 (work in 479 progress), February 2015. 481 [I-D.ietf-stox-groupchat] 482 Saint-Andre, P., Corretge, S., and S. Loreto, 483 "Interworking between the Session Initiation Protocol 484 (SIP) and the Extensible Messaging and Presence Protocol 485 (XMPP): Groupchat", draft-ietf-stox-groupchat-10 (work in 486 progress), February 2015. 488 [RFC2779] Day, M., Aggarwal, S., and J. Vincent, "Instant Messaging 489 / Presence Protocol Requirements", RFC 2779, February 490 2000. 492 [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO 493 10646", STD 63, RFC 3629, November 2003. 495 [RFC3860] Peterson, J., "Common Profile for Instant Messaging 496 (CPIM)", RFC 3860, August 2004. 498 [RFC3862] Klyne, G. and D. Atkins, "Common Presence and Instant 499 Messaging (CPIM): Message Format", RFC 3862, August 2004. 501 [RFC3922] Saint-Andre, P., "Mapping the Extensible Messaging and 502 Presence Protocol (XMPP) to Common Presence and Instant 503 Messaging (CPIM)", RFC 3922, October 2004. 505 [RFC3923] Saint-Andre, P., "End-to-End Signing and Object Encryption 506 for the Extensible Messaging and Presence Protocol 507 (XMPP)", RFC 3923, October 2004. 509 [RFC3987] Duerst, M. and M. Suignard, "Internationalized Resource 510 Identifiers (IRIs)", RFC 3987, January 2005. 512 [UNICODE] The Unicode Consortium, "The Unicode Standard, Version 513 7.0.0", 2014, 514 . 516 Appendix A. Acknowledgements 518 The authors wish to thank the following individuals for their 519 feedback: Mary Barnes, Dave Cridland, Dave Crocker, Adrian Georgescu, 520 Christer Holmberg, Saul Ibarra Corretge, Olle Johansson, Paul 521 Kyzivat, Salvatore Loreto, Daniel-Constantin Mierla, and Tory Patnoe. 523 Special thanks to Ben Campbell for his detailed and insightful 524 reviews. 526 The authors gratefully acknowledge the assistance of Markus Isomaki 527 and Yana Stamcheva as the working group chairs and Gonzalo Camarillo 528 and Alissa Cooper as the sponsoring Area Directors. 530 Peter Saint-Andre wishes to acknowledge Cisco Systems, Inc., for 531 employing him during his work on earlier versions of this document. 533 Authors' Addresses 535 Peter Saint-Andre 536 &yet 538 Email: peter@andyet.com 539 URI: https://andyet.com/ 541 Avshalom Houri 542 IBM 543 Rorberg Building, Pekris 3 544 Rehovot 76123 545 Israel 547 Email: avshalom@il.ibm.com 549 Joe Hildebrand 550 Cisco Systems, Inc. 551 1899 Wynkoop Street, Suite 600 552 Denver, CO 80202 553 USA 555 Email: jhildebr@cisco.com