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Versions: 00                                                            
MASQUE                                                           M. Duke
Internet-Draft                                                  F5, Inc.
Intended status: Experimental                            25 January 2021
Expires: 29 July 2021


  The Other-Transport Extension: Arbitrary Transports over CONNECT-UDP
                  draft-duke-masque-other-transport-00

Abstract

   This document describes an extension to the HTTP CONNECT-UDP method
   [CONNECTUDP] that supports tunneling of other transport protocols, as
   long as the first four octets of those protocols encode the source
   and destination ports.

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 https://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 29 July 2021.

Copyright Notice

   Copyright (c) 2021 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 (https://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.





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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Conventions and Definitions . . . . . . . . . . . . . . .   3
   2.  Other-Transport Header Definition . . . . . . . . . . . . . .   3
   3.  Datagram Encoding of Proxied Packets  . . . . . . . . . . . .   4
   4.  Stream Encoding of Proxied Packets  . . . . . . . . . . . . .   4
   5.  HTTP Intermediaries . . . . . . . . . . . . . . . . . . . . .   4
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
     7.1.  HTTP Header . . . . . . . . . . . . . . . . . . . . . . .   5
     7.2.  Stream Chunk Type Registration  . . . . . . . . . . . . .   5
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   The HTTP CONNECT method (section 4.3.6 of [RFC7231]) has long
   provided a means of tunneling a TCP connection over an HTTP stream.
   The CONNECT-UDP method [CONNECTUDP] extends this capability to
   include UDP datagrams over a stream.

   As CONNECT-UDP delivers discrete datagrams to each endpoint, it can
   extend conceptually to any packetized protocol.  The Other-Transport
   extension allows a CONNECT-UDP proxy to tunnel packets with non-TCP,
   non-UDP protocol numbers, as long as the corresponding protocol meets
   minimal formatting requirements.

   Specifically, any protocol header where the first four octets encode
   the source and destination ports can be tunneled using this
   framework.  The client and proxy include all other protocol header
   information in the datagrams delivered over the tunnel.  For example,
   33 (DCCP, [RFC4330]); 132 (SCTP, [RFC4960]); and 136 (UDPLite,
   [RFC3828]) would all be valid candidates for Other-Transport.

   In principle, TCP can be proxied using this extension as well.  This
   might provide advantages over traditional HTTP CONNECT if the
   client's TCP implementation has features lacking at the proxy.










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1.1.  Conventions and Definitions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   In this document, we use the term "proxy" to refer to the HTTP server
   that opens the UDP socket and responds to the CONNECT-UDP request.
   If there are HTTP intermediaries (as defined in Section 2.3 of
   [RFC7230]) between the client and the proxy, those are referred to as
   "intermediaries" in this document.

2.  Other-Transport Header Definition

   "Other-Transport" is an Item Structured Header [HDRSTRUCT].  Its ABNF
   is:

   Other-Transport = sf-integer

   The value MUST be between 0 and 255, inclusive.  Any other value is
   malformed.  This value indicates the value of the Protocol Number
   (IPv4) or Next Header (IPv6) in IP headers corresponding to the
   CONNECT-UDP stream.

   An Other-Transport header is ignored in any method other than
   CONNECT-UDP.

   A client that sends this header MUST include the entire transport
   header, with the exception of the first four octets, in each HTTP/3
   DATAGRAM or Stream Chunk payload it sends.  It MUST process incoming
   datagrams with the same assumption.

   When a client sends the Other-Transport header field, it MUST use a
   value that corresponds to a protocol whose first four octets of each
   packet correspond to the source and destination ports.  For example,
   33 (DCCP, [RFC4330]); 132 (SCTP, [RFC4960]); and 136 (UDPLite,
   [RFC3828]) would all be valid choices.

   A proxy MUST NOT include this header unless it will prepend and strip
   port numbers instead of entire UDP headers, and use the Protocol
   Number in IP headers for both packets to the server and for
   demultiplexing incoming server packets.

   A proxy MAY choose not to send the header due to policy regarding
   specific protocol numbers.




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   This extension is said to have been negotiated when both client and
   proxy indicate support for it in their CONNECT-UDP request and
   response using the same value.

   If the server responds without the Other-Transport header, the client
   may either proceed with UDP datagrams or close the stream.

   A response with a Other-Transport value other than that provided by
   the client is malformed.

3.  Datagram Encoding of Proxied Packets

   All DATAGRAM frames corresponding to the negotiated Datagram-Flow-Id
   headers are processed in accordance with the Other-Transport
   extension, if negotiated.

   All DATAGRAM frames MUST include the entire IP payload with the
   exception of the first four octets.

   If a client sent an Other-Transport header, it MUST NOT send DATAGRAM
   frames until it confirms this extension has been negotiated.  If the
   proxy does not support Other-Transport, it will interpret DATAGRAM
   frames as UDP payloads, with unpredictable results.

4.  Stream Encoding of Proxied Packets

   Endpoints use the 0x10 Stream Chunk Type to encode datagrams.

   Clients MAY send payloads using Stream Chunks before negotiation is
   complete.  Proxies that do not support the extension will simply
   ignore these chunks.

5.  HTTP Intermediaries

   HTTP Intermediaries that discover that an upstream proxy does not
   support the Other-Transport header MUST abort the stream in the
   direction of the client.

6.  Security Considerations

   CONNECT-UDP streams that use the Other-Transport header have similar
   security properties to other CONNECT-UDP streams, as described in
   [CONNECTUDP].

   However, as more of the transport header originates at the server,
   and the tunneled protocols are less ubiquitous than UDP, these
   headers may serve to fingerprint the protocol implementation that
   generated them.



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   Furthermore, additional control over packet headers enhances the
   ability of clients to induce the proxy to generate certain packets,
   which might have undesirable effects in the network while being less
   traceable to the client.

7.  IANA Considerations

7.1.  HTTP Header

   This document requests that IANA registers the "Other-Transport"
   header in the "Permanent Message Header Field Names" registry
   maintained at <https://www.iana.org/assignments/message-headers>.

     +-------------------+----------+--------+---------------+
     | Header Field Name | Protocol | Status |   Reference   |
     +-------------------+----------+--------+---------------+
     |   Other-Transport |   http   |  std   | This document |
     +-------------------+----------+--------+---------------+

7.2.  Stream Chunk Type Registration

   This document will request IANA to register the following entry in
   the "CONNECT-UDP Stream Chunk Type" registry [CONNECTUDP]:

   +-------+-----------------+-------------------------+---------------+
   | Value |      Type       |       Description       |   Reference   |
   +-------+-----------------+-------------------------+---------------+
   | 0x10  | OTHER_TRANSPORT | Other Transport Protocol| This document |
   +-------+-----------------+-------------------------+---------------+

8.  References

8.1.  Normative References

   [CONNECTUDP]
              Schinazi, D., "The CONNECT-UDP HTTP Method", Work in
              Progress, Internet-Draft, draft-ietf-masque-connect-udp-
              03, 5 January 2021, <http://www.ietf.org/internet-drafts/
              draft-ietf-masque-connect-udp-03.txt>.

   [HDRSTRUCT]
              Nottingham, M. and P. Kamp, "Structured Field Values for
              HTTP", Work in Progress, Internet-Draft, draft-ietf-
              httpbis-header-structure-19, 3 June 2020,
              <http://www.ietf.org/internet-drafts/draft-ietf-httpbis-
              header-structure-19.txt>.





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   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

8.2.  Informative References

   [RFC3828]  Larzon, L-A., Degermark, M., Pink, S., Jonsson, L-E., Ed.,
              and G. Fairhurst, Ed., "The Lightweight User Datagram
              Protocol (UDP-Lite)", RFC 3828, DOI 10.17487/RFC3828, July
              2004, <https://www.rfc-editor.org/info/rfc3828>.

   [RFC4330]  Mills, D., "Simple Network Time Protocol (SNTP) Version 4
              for IPv4, IPv6 and OSI", RFC 4330, DOI 10.17487/RFC4330,
              January 2006, <https://www.rfc-editor.org/info/rfc4330>.

   [RFC4960]  Stewart, R., Ed., "Stream Control Transmission Protocol",
              RFC 4960, DOI 10.17487/RFC4960, September 2007,
              <https://www.rfc-editor.org/info/rfc4960>.

   [RFC7230]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Message Syntax and Routing",
              RFC 7230, DOI 10.17487/RFC7230, June 2014,
              <https://www.rfc-editor.org/info/rfc7230>.

   [RFC7231]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
              DOI 10.17487/RFC7231, June 2014,
              <https://www.rfc-editor.org/info/rfc7231>.

Acknowledgments

Author's Address

   Martin Duke
   F5, Inc.
   801 5th Ave
   Seattle, Washington, 98104,
   United States of America

   Email: martin.h.duke@gmail.com






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