MASQUE                                                 A. Chernyakhovsky
Internet-Draft                                                 D. McCall
Intended status: Standards Track                             D. Schinazi
Expires: 28 February 2022                                     Google LLC
                                                          27 August 2021


                   A Routing Extension to CONNECT-IP
               draft-cms-masque-connect-ip-ext-routes-00

Abstract

   This document describes an extension to the CONNECT-IP HTTP method.
   This extension allows both endpoints to negotiate routes.  This
   enables split-tunnel VPN services, and network-to-network VPNs.

Discussion Venues

   This note is to be removed before publishing as an RFC.

   Discussion of this document takes place on the Multiplexed
   Application Substrate over QUIC Encryption Working Group mailing list
   (masque@ietf.org), which is archived at
   https://mailarchive.ietf.org/arch/browse/masque/.

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
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   This Internet-Draft will expire on 28 February 2022.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.





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   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
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   provided without warranty as described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Conventions and Definitions . . . . . . . . . . . . . . .   3
   2.  Routes  . . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Capsules  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  ROUTE_ADVERTISEMENT Capsule . . . . . . . . . . . . . . .   3
     3.2.  ROUTE_REJECTION Capsule . . . . . . . . . . . . . . . . .   4
     3.3.  ROUTE_RESET Capsule . . . . . . . . . . . . . . . . . . .   5
     3.4.  ATOMIC_START Capsule  . . . . . . . . . . . . . . . . . .   5
     3.5.  ATOMIC_END Capsule  . . . . . . . . . . . . . . . . . . .   6
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
     5.1.  Capsule Type Registrations  . . . . . . . . . . . . . . .   6
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   7
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   7
   Appendix A.  Examples . . . . . . . . . . . . . . . . . . . . . .   8
     A.1.  Consumer VPN  . . . . . . . . . . . . . . . . . . . . . .   8
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   This document describes an extension to the CONNECT-IP HTTP method
   [CONNECT-IP].  This extension allows both endpoints to negotiate
   routes.  This enables split-tunnel VPN services, and network-to-
   network VPNs.

   CONNECT-IP allows endpoints to set up an IP tunnel between one
   another but does not allow exchanging which routes are supported
   though the tunnel.  This extension can be used to connect an endpoint
   or network to another network without changing default routes.









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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 responds to the CONNECT-IP 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.  Routes

   Endpoints have the ability to advertise and reject routes using the
   ROUTE_ADVERTISEMENT (Section 3.1) and ROUTE_REJECTION (Section 3.1)
   capsule.  Note that these capsules are purely informational: receipt
   of a ROUTE_ADVERTISEMENT capsule does not require the recipient to
   start routing traffic to its peer.  Additionally, if an endpoint
   receives a ROUTE_REJECTION for a given prefix that it had previously
   received a ROUTE_ADVERTISEMENT capsule for, then the two cancel out
   and the endpoint MUST remove its state from the ROUTE_ADVERTISEMENT
   capsule instead of installing new state for the ROUTE_REJECTION
   capsule.  Conversely, the same is true of a ROUTE_ADVERTISEMENT that
   matches a previous ROUTE_REJECTION.  Routes are handled via longest-
   prefix-first preference, meaning that if a given IP prefix is covered
   by multiple route advertisement and route rejections, the one with
   the longest prefix is used.

   When processing ROUTE_ADVERTISEMENT capsules, endpoints MUST check
   their local policy before deciding whether to forward packets to
   their peer.  Since ignoring these capsules is allowed by the
   protocol, such policy decisions will not prevent interoperability.

3.  Capsules

3.1.  ROUTE_ADVERTISEMENT Capsule

   The ROUTE_ADVERTISEMENT capsule allows an endpoint to communicate to
   its peer that it is willing to route traffic to a given prefix.  This
   indicates that the sender has an existing route to the prefix, and
   notifies its peer that if the receiver of the ROUTE_ADVERTISEMENT
   capsule sends IP packets for this prefix in HTTP Datagrams, the
   sender of the capsule will forward them along its preexisting route.
   This capsule uses a Capsule Type of 0xfff102.  Its value uses the
   following format:



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   ROUTE_ADVERTISEMENT Capsule {
     IP Version (8),
     IP Address (32..128),
     IP Prefix Length (8),
   }

                Figure 1: ROUTE_ADVERTISEMENT Capsule Format

   IP Version:  IP Version of this route advertisement.  MUST be either
      4 or 6.

   IP Address:  IP address of the advertised route.  If the IP Version
      field has value 4, the IP Address field SHALL have a length of 32
      bits.  If the IP Version field has value 6, the IP Address field
      SHALL have a length of 128 bits.

   IP Prefix Length:  Length of the IP Prefix of the advertised route,
      in bits.  MUST be lesser or equal to the length of the IP Address
      field, in bits.

   Upon receiving the ROUTE_ADVERTISEMENT capsule, an endpoint MAY start
   routing IP packets in that prefix to its peer.

3.2.  ROUTE_REJECTION Capsule

   The ROUTE_REJECTION capsule allows an endpoint to communicate to its
   peer that it is not willing to route traffic to a given prefix.  This
   capsule uses a Capsule Type of 0xfff103.  Its value uses the
   following format:

   ROUTE_REJECTION Capsule {
     IP Version (8),
     IP Address (32..128),
     IP Prefix Length (8),
   }

                  Figure 2: ROUTE_REJECTION Capsule Format

   IP Version:  IP Version of this route rejection.  MUST be either 4 or
      6.

   IP Address:  IP address of the rejected route.  If the IP Version
      field has value 4, the IP Address field SHALL have a length of 32
      bits.  If the IP Version field has value 6, the IP Address field
      SHALL have a length of 128 bits.

   IP Prefix Length:  Length of the IP Prefix of the advertised route,




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      in bits.  MUST be lesser or equal to the length of the IP Address
      field, in bits.

   Upon receiving the ROUTE_REJECTION capsule, an endpoint MUST stop
   routing IP packets in that prefix to its peer.  Note that this
   capsule can be reordered with DATAGRAM frames, and therefore an
   endpoint that receives packets for routes it has rejected MUST NOT
   treat that as an error.

3.3.  ROUTE_RESET Capsule

   The ROUTE_RESET capsule allows an endpoint to cancel any routes it
   had previously advertised or denied.  This capsule uses a Capsule
   Type of 0xfff104.  Its value uses the following format:

   ROUTE_RESET Capsule {
   }

                    Figure 3: ROUTE_RESET Capsule Format

   Upon receiving the ROUTE_RESET capsule, an endpoint MUST stop routing
   IP packets to its peer.  Note that this capsule can be reordered with
   DATAGRAM frames, and therefore an endpoint that receives packets for
   routes it has rejected MUST NOT treat that as an error.

   The main purpose of the ROUTE_RESET capsule is to allow endpoints to
   not have to remember the full list of routes they have shared with
   their peer.  In practice, it is expected that ROUTE_RESET capsules
   will be closely followed by ROUTE_ADVERTISEMENT capsules that will
   refill the routing table that was just cleared.

3.4.  ATOMIC_START Capsule

   The ATOMIC_START capsule allows an endpoint to create an atomic set
   of capsules.  This capsule uses a Capsule Type of 0xfff106.  Its
   value uses the following format:

   ATOMIC_START Capsule {
   }

                   Figure 4: ATOMIC_START Capsule Format

   Upon receiving an ATOMIC_START capsule, an endpoint MUST buffer all
   incoming known CONNECT-IP-specific capsules (i.e., capsules defined
   in this document) until it receives an ATOMIC_END capsule.  Endpoints
   MUST NOT send two ATOMIC_START capsules without an ATOMIC_END capsule
   between them.




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   Endpoints MUST NOT buffer unknown capsules.  Endpoints MAY choose to
   immediately process IP_PACKET and SHUTDOWN capsules instead of
   buffering them.  Capsules defined in other documents are by default
   not buffered by ATOMIC_START.  Extensions that register new capsule
   types MAY specify that these capsules should be buffered by
   ATOMIC_START, and whether it is allowed to skip buffering for them.

   The purpose of this frame is to avoid timing issues where an endpoint
   installs a route before an important route rejection was received.
   Endpoints SHOULD group their initial configuration into an atomic
   block to allow their peer to mark the tunnel as operational once the
   whole block is parsed.

3.5.  ATOMIC_END Capsule

   The ATOMIC_END capsule allows an endpoint to end an atomic set of
   capsules.  This capsule uses a Capsule Type of 0xfff107.  Its value
   uses the following format:

   ATOMIC_END Capsule {
   }

                    Figure 5: ATOMIC_END Capsule Format

   Upon receiving an ATOMIC_END capsule, an endpoint MUST parse all
   previously buffered capsules, in order of receipt.  Endpoints MUST
   NOT send an ATOMIC_END capsule without a preceding ATOMIC_START
   capsule.

4.  Security Considerations

   In theory, endpoints could use ROUTE_ADVERTISEMENT capsules to divert
   traffic from naive endpoints.  To avoid this, receivers of
   ROUTE_ADVERTISEMENT capsules MUST check their local policy before
   acting on such capsules, see Section 2.

5.  IANA Considerations

5.1.  Capsule Type Registrations

   This document will request IANA to add the following values to the
   "HTTP Capsule Types" registry created by [HTTP-DGRAM]:









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+----------+---------------------+---------------------+---------------+
|   Value  |        Type         |      Description    |   Reference   |
+----------+---------------------+---------------------+---------------+
| 0xfff102 | ROUTE_ADVERTISEMENT | Route Advertisement | This document |
| 0xfff103 |   ROUTE_REJECTION   | Route Rejection     | This document |
| 0xfff104 |     ROUTE_RESET     | Route Reset         | This document |
| 0xfff106 |    ATOMIC_START     | Atomic Start        | This document |
| 0xfff107 |     ATOMIC_END      | Atomic End          | This document |
+----------+---------------------+---------------------+---------------+

6.  References

6.1.  Normative References

   [HTTP-DGRAM]
              Schinazi, D. and L. Pardue, "Using Datagrams with HTTP",
              Work in Progress, Internet-Draft, draft-ietf-masque-h3-
              datagram-03, 12 July 2021,
              <https://datatracker.ietf.org/doc/html/draft-ietf-masque-
              h3-datagram-03>.

   [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/rfc/rfc2119>.

   [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/rfc/rfc7230>.

   [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/rfc/rfc8174>.

6.2.  Informative References

   [CONNECT-IP]
              Chernyakhovsky, A., McCall, D., and D. Schinazi, "The
              CONNECT-IP HTTP Method", Work in Progress, Internet-Draft,
              draft-cms-masque-connect-ip-02, 27 August 2021,
              <https://datatracker.ietf.org/doc/html/draft-cms-masque-
              connect-ip-02>.








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   [REQS]     Chernyakhovsky, A., McCall, D., and D. Schinazi,
              "Requirements for a MASQUE Protocol to Proxy IP Traffic",
              Work in Progress, Internet-Draft, draft-ietf-masque-ip-
              proxy-reqs-03, 27 August 2021,
              <https://datatracker.ietf.org/doc/html/draft-ietf-masque-
              ip-proxy-reqs-03>.

Appendix A.  Examples

A.1.  Consumer VPN

   In this scenario, the client will typically receive a single IP
   address that the proxy has picked from a pool of addresses it
   maintains.  The client will route all traffic through the tunnel.
   The exchange could look as follows:

       Client                                             Server

       ADDRESS_REQUEST          -------->
         IP Version = 4
         IP Address = 0.0.0.0
         IP Prefix Length = 0

                                <--------  ADDRESS_ASSIGN
                                             IP Version = 4
                                             IP Address = 192.0.2.42
                                             IP Prefix Length = 32

                                <--------  ROUTE_ADVERTISEMENT
                                             IP Version = 4
                                             IP Address = 0.0.0.0
                                             IP Prefix Length = 0

Acknowledgments

   The design of CONNECT-IP was inspired by discussions in the MASQUE
   working group around [REQS].  The authors would like to thank
   participants in those discussions for their feedback.

Authors' Addresses

   Alex Chernyakhovsky
   Google LLC
   1600 Amphitheatre Parkway
   Mountain View, California 94043,
   United States of America

   Email: achernya@google.com



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   Dallas McCall
   Google LLC
   1600 Amphitheatre Parkway
   Mountain View, California 94043,
   United States of America

   Email: dallasmccall@google.com


   David Schinazi
   Google LLC
   1600 Amphitheatre Parkway
   Mountain View, California 94043,
   United States of America

   Email: dschinazi.ietf@gmail.com



































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