Network Working Group M. Petit-Huguenin Internet-Draft 8x8, Inc. Intended status: Standards Track April 22, 2008 Expires: October 24, 2008 Traversal Using Relays around NAT (TURN) Uniform Resource Identifiers draft-petithuguenin-behave-turn-uri-00 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on October 24, 2008. Abstract This document defines two URIs and the resolution mechanism to convert these URIs to a list of server transport addresses that can be used between a TURN client and server. Petit-Huguenin Expires October 24, 2008 [Page 1]
Internet-Draft TURN URIs April 2008 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Syntax of a TURN or TURNS URI . . . . . . . . . . . . . . . . . 3 4. TURN or TURNS URI Resolution . . . . . . . . . . . . . . . . . 3 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 6. Normative References . . . . . . . . . . . . . . . . . . . . . 5 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 6 Intellectual Property and Copyright Statements . . . . . . . . . . 7 Petit-Huguenin Expires October 24, 2008 [Page 2]
Internet-Draft TURN URIs April 2008 1. Introduction The TURN [I-D.ietf-behave-turn] specification defines a process for a TURN client to find TURN servers by using DNS SRV resource records, but this process does not let the TURN servers administrator provision the preferred TURN transport protocol between the client and the servers and for the TURN client to discover this preference. This document defines a S-NAPTR application [RFC3958] for this purpose. This application defines RELAY as application service tag and turn.udp, turn.tcp and turn.tls as application protocol tags. To simplify the provisioning of TURN client, this document also defines a TURN and a TURNS URI and a resolution mechanism to convert this URIs into a list of IP addresses, ports and TURN transport protocols. 2. Terminology 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 [RFC2119]. 3. Syntax of a TURN or TURNS URI A TURN/TURNS URI has the following ABNF syntax [RFC5234]: turnURI = scheme ":" host [ ":" port ] [ ";transport=" transport ] scheme = "turn" / "turns" transport = "udp" / "tcp" The URI host and port components are specified in [RFC3986]. 4. TURN or TURNS URI Resolution The URI resolution algorithm uses the URI scheme, URI host, URI port and URI transport components as input. It also uses a list ordered by preference of TURN transports (UDP, TCP, TLS) supported by the application using the TURN client. The output of the algorithm is a list of IP address, port and transport tuples that a TURN client can try to contact a TURN server. First the resolution algorithm checks that the URI can be resolved with the list of TURN transports supported: Petit-Huguenin Expires October 24, 2008 [Page 3]
Internet-Draft TURN URIs April 2008 o If the URI scheme component is defined as turn and the URI transport component is defined as udp but the list of TURN transports does not contain UDP then the resolution MUST stop with an error. o If the URI scheme component is defined as turn and the URI transport component is defined as tcp but the list of TURN transports does not contain TCP or TLS then the resolution MUST stop with an error. o If the URI scheme component is defined as turns and the URI transport component is defined as udp then the algorithm MUST stop with an error. o If the URI scheme component is defined as turns and the URI transport component is defined as tcp but the list of TURN transports does not contain TLS then the resolution MUST stop with an error. o If the URI scheme component is defined as turns and the URI transport component is not defined but the list of TURN transports does not contain TLS then the resolution MUST stop with an error. Then the algorithm applies the following steps. The resolution stops when a TURN client successfully contacts a TURN server. 1. If the URI host component is an IP address then it indicates the specific IP address to be used. If the URI port component is not defined, the default port declared in [I-D.ietf-behave-turn] for the SRV service name defined in the URI scheme component is used. If the URI transport component is defined then the TURN UDP transport is used if the URI scheme component is turn and the URI transport component is udp, the TURN TCP transport is used if the URI scheme component is turn and the URI transport component is tcp and the TURN TLS transport is used if the URI scheme component is turns and the URI transport component is tcp. If the URI transport component is not defined, the TURN transports supported by the application are tried by preference order. If the TURN client cannot contact a TURN server with this IP address and port on any of the transports then the resolution MUST stop with an error. 2. If the URI host component is a domain name and the URI port component is defined, then the URI host component is resolved to a list of IP addresses via DNS A and AAAA queries. If the URI transport component is defined then the TURN UDP transport is used if the URI scheme component is turn and the URI transport component is udp, the TURN TCP transport is used if the URI scheme component is turn and the URI transport component is tcp and the TURN TLS transport is used if the URI scheme component is turns and the URI transport component is tcp. If the URI transport component is not defined, the TURN transports supported by the application are tried by preference order. If the TURN Petit-Huguenin Expires October 24, 2008 [Page 4]
Internet-Draft TURN URIs April 2008 client cannot contact a TURN server with this port and any combination of transports and resolved IP addresses then the resolution MUST stop with an error. 3. If the URI host component is a domain name and the URI port component is not defined but the URI transport component is defined then the URI host component is converted to a list of IP address and port tuples via a DNS SRV query as defined in [I-D.ietf-behave-turn] section 6.1. The URI scheme component is used for the service name and the URI transport component is used for the protocol name in the SRV algorithm [RFC2782]. If the TURN client cannot contact a TURN server on any of the IP address, port and transport tuples returned by the SRV algorithm then the resolution MUST stop with an error. If the DNS SRV query does not return any result, then the URI host component is converted to a list of IP addresses by using the default port declared in [I-D.ietf-behave-turn] for the SRV service name defined in the URI scheme component and step 2 of the resolution algorithm. 4. If the URI host component is a domain name and the URI port and transport components are not defined, then the URI host component is converted to an ordered list of IP address, port and transport tuples via the S-NAPTR algorithm defined in [RFC3958]. The Application Service Tag used is RELAY. The TURN transports supported by the application are tried by preference order by using the turn.udp Application Protocol Tag if the TURN transport is UDP, the turn.tcp Application Protocol Tag if the TURN transport is TCP and the turn.tls Application Protocol Tag if the TURN transport is TLS. If the TURN client cannot contact a TURN server with any of the IP address, port and transport tuples returned by the S-NAPTR algorithm then then the resolution MUST stop with an error. If the first NAPTR SRV query does not return any result then the URI host component is converted to a list of IP address and port tuples by trying the TURN transports supported by the application by preference order and step 3 of the resolution algorithm. 5. Acknowledgements Thanks to Eilon Yardeni for his comments on this document. 6. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2782] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for Petit-Huguenin Expires October 24, 2008 [Page 5]
Internet-Draft TURN URIs April 2008 specifying the location of services (DNS SRV)", RFC 2782, February 2000. [RFC3958] Daigle, L. and A. Newton, "Domain-Based Application Service Location Using SRV RRs and the Dynamic Delegation Discovery Service (DDDS)", RFC 3958, January 2005. [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005. [RFC5234] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, January 2008. [I-D.ietf-behave-turn] Rosenberg, J., Mahy, R., and P. Matthews, "Traversal Using Relays around NAT (TURN): Relay Extensions to Session Traversal Utilities for NAT (STUN)", draft-ietf-behave-turn-07 (work in progress), February 2008. Author's Address Marc Petit-Huguenin 8x8, Inc. 3151 Jay Street Santa Clara, CA 95054 US Phone: +1 408 654 0875 Email: marc@8x8.com Petit-Huguenin Expires October 24, 2008 [Page 6]
Internet-Draft TURN URIs April 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Petit-Huguenin Expires October 24, 2008 [Page 7]