AVTCORE Working Group B. Aboba INTERNET-DRAFT Microsoft Corporation Updates: 7983, 5764 G. Salgueiro Category: Standards Track Cisco Systems Expires: July 28, 2022 C. Perkins University of Glasgow 28 January 2022 Multiplexing Scheme Updates for QUIC draft-ietf-avtcore-rfc7983bis-02.txt Abstract This document defines how QUIC, Datagram Transport Layer Security (DTLS), Real-time Transport Protocol (RTP), RTP Control Protocol (RTCP), Session Traversal Utilities for NAT (STUN), Traversal Using Relays around NAT (TURN), and ZRTP packets are multiplexed on a single receiving socket. This document updates RFC 7983 and RFC 5764. 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 July 28, 2022. Aboba, et. al Standards Track [Page 1] INTERNET-DRAFT Multiplexing Scheme Updates for QUIC 28 January 2022 Copyright Notice Copyright (c) 2022 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 . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2. Multiplexing of TURN Channels . . . . . . . . . . . . . . . . 3 3. Updates to RFC 7983 . . . . . . . . . . . . . . . . . . . . . 4 4. Security Considerations . . . . . . . . . . . . . . . . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 6.1. Normative References . . . . . . . . . . . . . . . . . . 6 6.2. Informative References . . . . . . . . . . . . . . . . . 7 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 Aboba, et. al Standards Track [Page 2] INTERNET-DRAFT Multiplexing Scheme Updates for QUIC 28 January 2022 1. Introduction "Multiplexing Scheme Updates for Secure Real-time Transport Protocol (SRTP) Extension for Datagram Transport Layer Security (DTLS)" [RFC7983] defines a scheme for a Real-time Transport Protocol (RTP) [RFC3550] receiver to demultiplex DTLS [RFC6347], Session Traversal Utilities for NAT (STUN) [RFC8489], Secure Real-time Transport Protocol (SRTP) / Secure Real-time Transport Control Protocol (SRTCP) [RFC3711], ZRTP [RFC6189] and TURN Channel packets arriving on a single port. This document updates [RFC7983] and [RFC5764] to also allow QUIC [RFC9000] to be multiplexed on the same port. Currently implemented QUIC congestion control mechanisms are unsuitable for transport of media in realtime communications use cases. As a result, peer-to- peer operation in WebRTC scenarios, described in [P2P-QUIC] [P2P- QUIC-TRIAL], used RTP for transport of audio and video while QUIC was used for data exchange. In such a scenario, SRTP [RFC3711] is keyed using DTLS-SRTP [RFC5764] and therefore SRTP/SRTCP [RFC3550], STUN, TURN, DTLS [RFC6347] and QUIC need to be multiplexed on the same port. If QUIC congestion control is modified to enable peer-to-peer transport of audio and video with low latency [I-D.engelbart-rtp-over-quic] as well as data, only STUN, TURN and QUIC would need to be multiplexed on the same port. Since new versions of QUIC are allowed to change aspects of the wire image, there is no guarantee that future versions of QUIC beyond version 1 will adhere to the multiplexing scheme described in this document. 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. Multiplexing of TURN Channels TURN channels are an optimization where data packets are exchanged with a 4-byte prefix instead of the standard 36-byte STUN overhead (see Section 3.5 of [RFC8656]). [RFC7983] allocated the values from 64 to 79 in order to allow TURN channels to be demultiplexed when the TURN Client does the channel binding request in combination with the demultiplexing scheme described in [RFC7983]. As noted in [I-D.aboba-avtcore-quic-multiplexing], the first octet of Aboba, et. al Standards Track [Page 3] INTERNET-DRAFT Multiplexing Scheme Updates for QUIC 28 January 2022 a QUIC short header packet falls in the range 64 to 127, thereby overlapping with the allocated range for TURN channels of 64 to 79. The first octet of QUIC long header packets fall in the range 192 to 255. Since QUIC long header packets preceed QUIC short header packets, if no packets with a first octet in the range of 192 to 255 have been received, a packet whose first octet is in the range of 64 to 79 can be demultplexed unambiguously as TURN Channel traffic. Since WebRTC implementations supporting QUIC data exchange do not utilize TURN Channels, once packets with a first octet in the range of 192 to 255 have been received, a packet whose first octet is in the range of 64 to 127 can be demultiplexed as QUIC traffic. 3. Updates to RFC 7983 This document updates the text in Section 7 of [RFC7983] (which in turn updates [RFC5764]) as follows: OLD TEXT The process for demultiplexing a packet is as follows. The receiver looks at the first byte of the packet. If the value of this byte is in between 0 and 3 (inclusive), then the packet is STUN. If the value is between 16 and 19 (inclusive), then the packet is ZRTP. If the value is between 20 and 63 (inclusive), then the packet is DTLS. If the value is between 64 and 79 (inclusive), then the packet is TURN Channel. If the value is in between 128 and 191 (inclusive), then the packet is RTP (or RTCP, if both RTCP and RTP are being multiplexed over the same destination port). If the value does not match any known range, then the packet MUST be dropped and an alert MAY be logged. This process is summarized in Figure 3. +----------------+ | [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 3: The DTLS-SRTP receiver's packet demultiplexing algorithm. END OLD TEXT Aboba, et. al Standards Track [Page 4] INTERNET-DRAFT Multiplexing Scheme Updates for QUIC 28 January 2022 NEW TEXT The process for demultiplexing a packet is as follows. The receiver looks at the first byte of the packet. If the value of this byte is in between 0 and 3 (inclusive), then the packet is STUN. If the value is between 16 and 19 (inclusive), then the packet is ZRTP. If the value is between 20 and 63 (inclusive), then the packet is DTLS. If the value is in between 128 and 191 (inclusive) then the packet is RTP (or RTCP, if both RTCP and RTP are being multiplexed over the same destination port). If the value is between 80 and 127 or between 192 and 255 (inclusive) then the packet is QUIC. If the value is between 64 and 79 inclusive, then if a packet has been previously forwarded that is in the range of 192 and 255, then the packet is QUIC, otherwise it is TURN Channel. If the value does not match any known range, then the packet MUST be dropped and an alert MAY be logged. This process is summarized in Figure 3. +----------------+ | [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 | | | [192..255] -+--> forward to QUIC +----------------+ (Long Header) Figure 3: The receiver's packet demultiplexing algorithm. END NEW TEXT 4. Security Considerations The solution discussed in this document could potentially introduce some additional security considerations beyond those detailed in [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 Aboba, et. al Standards Track [Page 5] INTERNET-DRAFT Multiplexing Scheme Updates for QUIC 28 January 2022 exchange [RFC9001] 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. 5. IANA Considerations This document does not require actions by IANA. 6. References 6.1. Normative References [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 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, . [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, . [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, . [RFC8489] Petit-Huguenin, M., Salgueiro, G., Rosenberg, J., Wing, D., Mahy, R. and P. Matthews, "Session Traversal Utilities for NAT (STUN), RFC 8489, DOI 10.17487/RFC8489, February 2020, . [RFC8656] Reddy, T., Johnston, A., Matthews, P. and J. Rosenberg, "Traversal Using Relays around NAT (TURN): Relay Extensions Aboba, et. al Standards Track [Page 6] INTERNET-DRAFT Multiplexing Scheme Updates for QUIC 28 January 2022 to Session Traversal Utilities for NAT (STUN)", RFC 8656, DOI 10.17487/RFC8656, February 2020, . [RFC9000] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based Multiplexed and Secure Transport", RFC 9000, DOI 10.17487/RFC9000, May 2021, . [RFC9001] Thomson, M., Ed. and S. Turner, Ed., "Using TLS to Secure QUIC", RFC 9001, DOI 10.17487/RFC9001, May 2021, . 6.2. Informative References [I-D.aboba-avtcore-quic-multiplexing] Aboba, B., Thatcher, P. and C. Perkins, "QUIC Multiplexing", draft-aboba-avtcore-quic-multiplexing-04 (work in progress), January 28, 2020. [I-D.engelbart-rtp-over-quic] Ott, J. and M. Engelbart, "RTP over QUIC", draft-engelbart- rtp-over-quic-01 (work in progress), October 25, 2021. [RFC6189] Zimmermann, P., Johnston, A., Ed., and J. Callas, "ZRTP: Media Path Key Agreement for Unicast Secure RTP", RFC 6189, DOI 10.17487/RFC6189, April 2011, . [RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347, January 2012, . [P2P-QUIC] Thatcher, P., Aboba, B. and R. Raymond, "QUIC API For Peer- to-Peer Connections", W3C ORTC Community Group Draft (work in progress), 23 May 2021, [P2P-QUIC-TRIAL] Hampson, S., "RTCQuicTransport Coming to an Origin Trial Near You (Chrome 73)", January 2019, Aboba, et. al Standards Track [Page 7] INTERNET-DRAFT Multiplexing Scheme Updates for QUIC 28 January 2022 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 Gonzalo Salgueiro Cisco Systems 7200-12 Kit Creek Road Research Triangle Park, NC 27709 United States of America Email: gsalguei@cisco.com Colin Perkins School of Computing Science University of Glasgow Glasgow G12 8QQ United Kingdom Email: csp@csperkins.org Aboba, et. al Standards Track [Page 8]