AVTCORE Working Group B. Aboba INTERNET-DRAFT Microsoft Corporation Category: Informational P. Thatcher Expires: April 23, 2019 Google C. Perkins University of Glasgow 23 October 2018 QUIC Multiplexing draft-aboba-avtcore-quic-multiplexing-02.txt Abstract If QUIC is to be used in a peer-to-peer manner, with NAT traversal, then it is necessary to be able to demultiplex QUIC and other protocols used in WebRTC on a single UDP port. This memo discusses options for demultiplexing. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on April 23, 2019. Aboba, et. al Informational [Page 1] INTERNET-DRAFT QUIC Multiplexing 23 October 2018 Copyright Notice Copyright (c) 2018 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2 2. Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Subsequent changes . . . . . . . . . . . . . . . . . . . . 4 3. Security Considerations . . . . . . . . . . . . . . . . . . . 4 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5.1. Informative references . . . . . . . . . . . . . . . . . . 5 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 1. Introduction QUIC [I-D.ietf-quic-transport] is a new network transport protocol. While it is initially intended as a replacement for TCP in order to better support HTTP/2 [RFC7540] it should eventually be useful as a general purpose transport. HTTP is an asymmetric client-server protocol, but other uses of QUIC might operate in a peer-to-peer manner and so will need effective NAT traversal using ICE [RFC5245], which which makes use of STUN [RFC5389] and TURN [RFC5766] to discover NAT bindings. Therefore for QUIC to be utilized for peer- to-peer data transport, QUIC and STUN must be able to multiplex on the same port. In a WebRTC scenario where RTP is used to transport audio and video and QUIC is used for data exchange, SRTP [RFC3711] is keyed using DTLS-SRTP [RFC5764] and therefore SRTP/SRTCP [RFC3550], STUN, TURN, DTLS [RFC6347] and QUIC will need to be multiplexed on the same port. Within the W3C, a Javascript API for the use of QUIC for peer-to-peer data exchange [WEBRTC-QUIC] is under development within the ORTC Aboba, et. al Informational [Page 2] INTERNET-DRAFT QUIC Multiplexing 23 October 2018 Community Group. As noted in [RFC7983] Figure 3, protocol demultiplexing currently relies upon differentiation based on the first octet, as follows: +----------------+ | [0..3] -+--> forward to STUN | | | [16..19] -+--> forward to ZRTP | | packet --> | [20..63] -+--> forward to DTLS | | | [64..79] -+--> forward to TURN Channel | | | [128..191] -+--> forward to RTP/RTCP +----------------+ Figure 1: RFC 7983 packet demultiplexing algorithm. As noted by Colin Perkins and Lars Eggert in [QUIC-Issue] this created a potential conflict with the design of the QUIC headers described in versions of [I-D.ietf-quic-transport] prior to -08. 1.1. 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]. 2. Solution At IETF 100, Colin Perkins presented a demultiplexing proposal [QUIC- MULTI]. The proposal which was subsequently proposed as a Pull Request to the QUIC Transport specification and merged in draft-ietf- quic-transport-08, involved renumbering of the QUIC long header packet type field as well as inverting the sense of the "C" bit in the short header packet. Aboba, et. al Informational [Page 3] INTERNET-DRAFT QUIC Multiplexing 23 October 2018 The demultiplexing algorithm resulting from the changes appears as follows: +----------------+ | [0..3] -+--> forward to STUN | | | [16..19] -+--> forward to ZRTP | | packet --> | [20..63] -+--> forward to DTLS | | | [64..79] -+--> forward to TURN Channel | [64..127] -+--> forward to QUIC (Short Header) | | | [128..191] -+--> forward to RTP/RTCP | [250..255] +--> forward to QUIC (Long Header) +----------------+ Figure 2: Revised packet demultiplexing algorithm. Note that while the above diagram has a potential conflict between packets sent in TURN Channels and the QUIC short header, this conflict is not considered serious for WebRTC where TURN Channels are rarely used. 2.1. Subsequent changes Since then, additional changes have been made to the QUIC transport headers. While the QUIC Long Header packet type field retains its original allocations between 0x7C and 0x7F, as of draft -15, the first octet of the Short Header now appears as follows: +-+-+-+-+-+-+-+-+ |0|K|1|1|0|R|R|R| +-+-+-+-+-+-+-+-+ Where: K = indicates the key phase. R = reserved bits, set randomly by endpoints not actively using them. This potentially produces values of the first octet in the ranges 48-55 which potentially conflicts with DTLS, and 80-87 which conflicts with TURN channels (not an issue). 3. Security Considerations The solutions discussed in this document could potentially introduce some additional security considerations beyond those detailed in Aboba, et. al Informational [Page 4] INTERNET-DRAFT QUIC Multiplexing 23 October 2018 [RFC7983]. Due to the additional logic required, if mis-implemented, heuristics have the potential to mis-classify packets. When QUIC is used for only for data exchange, the TLS-within-QUIC exchange [I-D.ietf-quic-tls] derives keys used solely to protect the QUIC data packets. If properly implemented, this should not affect the transport of SRTP nor the derivation of SRTP keys via DTLS-SRTP, but if badly implemented, both transport and key derivation could be adversely impacted. 4. IANA Considerations This document does not require actions by IANA. 5. References 5.1. Informative References [I-D.ietf-quic-tls] Thomson, M. and S. Turner, "Using Transport Layer Security (TLS) to Secure QUIC", draft-ietf-quic-tls-15 (work in progress), October 3, 2018. [I-D.ietf-quic-transport] Iyengar, J. and M. Thomson, "QUIC: A UDP-Based Multiplexed and Secure Transport", draft-ietf-quic-transport-15 (work in progress), October 3, 2018. [QUIC-Issue] Perkins, C., "QUIC header format/demultiplexing", https://github.com/quicwg/base-drafts/issues/426, March, 2017. [QUIC-MULTI] Perkins, C., "QUIC Multiplexing and Peer-to-Peer", presentation to IETF AVTCORE WG at IETF 100, , November 2017. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, "RTP: A Transport Protocol for Real-Time Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550, July Aboba, et. al Informational [Page 5] INTERNET-DRAFT QUIC Multiplexing 23 October 2018 2003, . [RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. Norrman, "The Secure Real-time Transport Protocol (SRTP)", RFC 3711, DOI 10.17487/RFC3711, March 2004, . [RFC5245] Rosenberg, J., "Interactive Connectivity Establishment (ICE): A Protocol for Network Address Translator (NAT) Traversal for Offer/Answer Protocols", RFC 5245, DOI 10.17487/RFC5245, April 2010, . [RFC5389] Rosenberg, J., Mahy, R., Matthews, P., and D. Wing, "Session Traversal Utilities for NAT (STUN)", RFC 5389, DOI 10.17487/RFC5389, October 2008, . [RFC5764] McGrew, D. and E. Rescorla, "Datagram Transport Layer Security (DTLS) Extension to Establish Keys for the Secure Real-time Transport Protocol (SRTP)", RFC 5764, DOI 10.17487/RFC5764, May 2010, . [RFC5766] Mahy, R., Matthews, P., and J. Rosenberg, "Traversal Using Relays around NAT (TURN): Relay Extensions to Session Traversal Utilities for NAT (STUN)", RFC 5766, DOI 10.17487/RFC5766, April 2010, . [RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347, January 2012, . [RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext Transfer Protocol Version 2 (HTTP/2)", RFC 7540, DOI 10.17487/RFC7540, May 2015, . [RFC7983] Petit-Huguenin, M. and G. Salgueiro, "Multiplexing Scheme Updates for Secure Real-time Transport Protocol (SRTP) Extension for Datagram Transport Layer Security (DTLS)", RFC 7983, DOI 10.17487/RFC7983, September 2016, . [WEBRTC-QUIC] Thatcher, P. and B. Aboba, "QUIC API For WebRTC", W3C Editor's Draft (work in progress), October 2018, Aboba, et. al Informational [Page 6] INTERNET-DRAFT QUIC Multiplexing 23 October 2018 Acknowledgments We would like to thank Martin Thomson, Roni Even and other participants in the IETF QUIC and AVTCORE working groups for their discussion of the QUIC multiplexing issue, and their input relating to potential solutions. Authors' Addresses Bernard Aboba Microsoft Corporation One Microsoft Way Redmond, WA 98052 USA Email: bernard.aboba@gmail.com Peter Thatcher Google 747 6th St S Kirkland, WA 98033 USA Email: pthatcher@google.com Colin Perkins School of Computing Science University of Glasgow Glasgow G12 8QQ United Kingdom Email: csp@csperkins.org Aboba, et. al Informational [Page 7]