Internet DRAFT - draft-cms-masque-connect-ip
draft-cms-masque-connect-ip
MASQUE A. Chernyakhovsky
Internet-Draft D. McCall
Intended status: Standards Track D. Schinazi
Expires: 28 February 2022 Google LLC
27 August 2021
The CONNECT-IP HTTP Method
draft-cms-masque-connect-ip-02
Abstract
This document describes the CONNECT-IP HTTP method. CONNECT-IP is
similar to CONNECT-UDP, but allows transmitting IP packets, without
being limited to just TCP like CONNECT or UDP like CONNECT-UDP.
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/.
Source for this draft and an issue tracker can be found at
https://github.com/DavidSchinazi/draft-cms-masque-connect-ip.
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 28 February 2022.
Chernyakhovsky, et al. Expires 28 February 2022 [Page 1]
Internet-Draft CONNECT-IP August 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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions and Definitions . . . . . . . . . . . . . . . 3
2. The CONNECT-IP Method . . . . . . . . . . . . . . . . . . . . 3
3. Transmitting IP Packets using HTTP Datagrams . . . . . . . . 4
4. Forwarding of IP Packets . . . . . . . . . . . . . . . . . . 4
5. Capsules . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5.1. ADDRESS_ASSIGN Capsule . . . . . . . . . . . . . . . . . 5
5.2. ADDRESS_REQUEST Capsule . . . . . . . . . . . . . . . . . 6
5.3. SHUTDOWN Capsule . . . . . . . . . . . . . . . . . . . . 6
6. Extensibility Considerations . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
8.1. HTTP Method . . . . . . . . . . . . . . . . . . . . . . . 7
8.2. Capsule Type Registrations . . . . . . . . . . . . . . . 8
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
9.1. Normative References . . . . . . . . . . . . . . . . . . 8
9.2. Informative References . . . . . . . . . . . . . . . . . 9
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 9
A.1. Consumer VPN . . . . . . . . . . . . . . . . . . . . . . 9
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
This document describes the CONNECT-IP HTTP method. CONNECT-IP is
similar to CONNECT-UDP, but allows transmitting IP packets, without
being limited to just TCP like CONNECT or UDP like CONNECT-UDP.
CONNECT-IP allows endpoints to set up an IP tunnel between one
another. This can be used to implement a consumer VPN, point-to-
point and point-to-network capabilities as described in [REQS].
Chernyakhovsky, et al. Expires 28 February 2022 [Page 2]
Internet-Draft CONNECT-IP August 2021
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. The CONNECT-IP Method
The CONNECT-IP method establishes a stream to an endpoint server that
then permits the exchange of control data, such as IP address
information and other relevant information for successfully
transmitting IP datagrams between hosts.
The request-target of a CONNECT-IP request is a URI [URI] which uses
the "https" scheme and a client-specified path. When using HTTP/2
[H2] or later, CONNECT-IP requests use HTTP pseudo-headers with the
following requirements:
* The ":method" pseudo-header field is set to "CONNECT-IP".
* The ":scheme" pseudo-header field is set to "https".
* The ":path" pseudo-header field is set to the value provided by
the client. That value MUST NOT be empty.
* The ":authority" pseudo-header field contains the host and port of
the proxy. The target of a CONNECT-IP request is the server
providing the CONNECT-IP featureset, not an individual endpoint
with which a connection is desired.
A CONNECT-IP request that does not conform to these restrictions is
malformed (see [H2], Section 8.1.2.6).
Any 2xx (Successful) response indicates that the proxy is willing to
open an IP tunnel between it and the client. Any response other than
a successful response indicates that the tunnel has not yet been
formed.
Chernyakhovsky, et al. Expires 28 February 2022 [Page 3]
Internet-Draft CONNECT-IP August 2021
A proxy MUST NOT send any Transfer-Encoding or Content-Length header
fields in a 2xx (Successful) response to CONNECT-IP. A client MUST
treat a successful response to CONNECT-IP containing any Content-
Length or Transfer-Encoding header fields as malformed.
A payload within a CONNECT-IP request message has no defined
semantics; a CONNECT-IP request with a non-empty payload is
malformed. Note that the CONNECT-IP stream is used to convey control
messages, but they are not semantically part of the request or
response themselves.
Responses to the CONNECT-IP method are not cacheable.
The lifetime of the tunnel is tied to the CONNECT-IP stream. Closing
the stream (via the FIN bit on a QUIC STREAM frame, or a QUIC
RESET_STREAM frame) closes the associated tunnel.
3. Transmitting IP Packets using HTTP Datagrams
IP packets are sent using HTTP Datagrams [HTTP-DGRAM]. The HTTP
Datagram Payload contains a full IP packet, from the IP Version field
until the last byte of the IP Payload. In order to use HTTP
Datagrams, the CONNECT-IP client will first decide whether or not to
use HTTP Datagram Contexts and then register its context ID (or lack
thereof) using the corresponding registration capsule, see
[HTTP-DGRAM].
Since HTTP Datagrams require prior negotiation (for example, in
HTTP/3 it is necessary to both send and receive the H3_DATAGRAM
SETTINGS Parameter), clients MUST NOT send any HTTP Datagrams until
they have established support on a given connection. If negotiation
of HTTP Datagrams fails (for example if an HTTP/3 SETTINGS frame was
received without the H3_DATAGRAM SETTINGS Parameter), the client MUST
consider its CONNECT-IP request as failed.
4. Forwarding of IP Packets
Since CONNECT-IP allows the transmission of IP packets over HTTP,
CONNECT-IP endpoints will most often forward these packets to and
from traditional IP interfaces. As such, CONNECT-IP endpoints act as
IP routers. When a CONNECT-IP endpoint receives an HTTP Datagram
containing an IP packet, it will parse the packet's IP header,
perform any local policy checks (e.g., source address validation),
check their routing table to pick an outbound interface, and then use
an implementation-specific mechanism (such as raw sockets) to send
the IP packet on that interface.
Chernyakhovsky, et al. Expires 28 February 2022 [Page 4]
Internet-Draft CONNECT-IP August 2021
Conversely, when a CONNECT-IP endpoint receives an IP packet whose
destination address does not match any local addresses, it consults
its routing table to pick a forwarding destination, and if the table
points to a CONNECT-IP tunnel, the endpoint performs the same
forwarding checks before transmitting the packet inside the tunnel.
Note that CONNECT-IP endpoints will decrement the IP Hop Count (or
TTL) upon encapsulation but not decapsulation. In other words, the
Hop Count is decremented right before an IP packet is transmitted in
an HTTP Datagram. This prevents infinite loops in the presence of
routing loops, and matches the choices in IPsec [IPSEC].
Endpoints MAY implement additional filtering policies on the IP
packets they forward.
5. Capsules
5.1. ADDRESS_ASSIGN Capsule
The ADDRESS_ASSIGN capsule allows an endpoint to inform its peer that
it has assigned an IP address to it. It allows assigning a prefix
which can contain multiple addresses. This capsule uses a Capsule
Type of 0xfff100. Its value uses the following format:
ADDRESS_ASSIGN Capsule {
IP Version (8),
IP Address (32..128),
IP Prefix Length (8),
}
Figure 1: ADDRESS_ASSIGN Capsule Format
IP Version: IP Version of this address assignment. MUST be either 4
or 6.
IP Address: Assigned IP address. 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 assigned, in bits. MUST
be lesser or equal to the length of the IP Address field, in bits.
Chernyakhovsky, et al. Expires 28 February 2022 [Page 5]
Internet-Draft CONNECT-IP August 2021
5.2. ADDRESS_REQUEST Capsule
The ADDRESS_REQUEST capsule allows an endpoint to request assignment
of an IP address from its peer. It allows the endpoint to optionally
indicate a preference for which address it would get assigned. This
capsule uses a Capsule Type of 0xfff101. Its value uses the
following format:
ADDRESS_REQUEST Capsule {
IP Version (8),
IP Address (32..128),
IP Prefix Length (8),
}
Figure 2: ADDRESS_REQUEST Capsule Format
IP Version: IP Version of this address request. MUST be either 4 or
6.
IP Address: Requested IP address. 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 requested, in bits. MUST
be lesser or equal to the length of the IP Address field, in bits.
Upon receiving the ADDRESS_REQUEST capsule, an endpoint SHOULD assign
an IP address to its peer, and then respond with an ADDRESS_ASSIGN
capsule to inform the peer of the assignment.
5.3. SHUTDOWN Capsule
The SHUTDOWN capsule allows an endpoint to communicate to its peer
that it is about to close the CONNECT-IP stream, with a string
explaining the reason for the shutdown. This capsule uses a Capsule
Type of 0xfff105. Its value uses the following format:
SHUTDOWN Capsule {
Reason Phrase (..),
}
Figure 3: SHUTDOWN Capsule Format
Reason Phrase: Additional diagnostic information for the shutdown.
Chernyakhovsky, et al. Expires 28 February 2022 [Page 6]
Internet-Draft CONNECT-IP August 2021
This SHOULD be a UTF-8 encoded string [UTF8], though the frame
does not carry information, such as language tags, that would aid
comprehension by any entity other than the one that created the
text.
Note that the SHUTDOWN capsule is informational, the tunnel is only
closed when its corresponding CONNECT-IP stream is closed. Endpoints
MAY close the tunnel with a reason phrase by sending the SHUTDOWN
capsule with the FIN bit set on the underlying QUIC STREAM frame that
carried it.
6. Extensibility Considerations
CONNECT-IP can be extended via multiple mechanisms to increase
functionality. There are three main ways to extend CONNECT-IP: HTTP
headers, Capsule Types, and HTTP Datagram Registration Extension
Data. For example, an authentication extension could define an HTTP
header that allows endpoints to send authentication credentials to
their peer during the creation of the tunnel. Alternatively, one
could specify an extension that defines a new Capsule Type which
allows exchanging DNS configuration between endpoints. Additionally,
an extension to CONNECT-IP can use multiple HTTP Datagram Contexts
[HTTP-DGRAM] simultaneously to compress some IP packets by
associating the compression context with an HTTP Datagram Context ID.
7. Security Considerations
There are significant risks in allowing arbitrary clients to
establish a tunnel to arbitrary servers, as that could allow bad
actors to send traffic and have it attributed to the proxy. Proxies
that support CONNECT-IP SHOULD restrict its use to authenticated
users. The HTTP Authorization header [AUTH] MAY be used to
authenticate clients. More complex authentication schemes are out of
scope for this document but can be implemented using CONNECT-IP
extensions.
Since CONNECT-IP endpoints can proxy IP packets send by their peer,
they SHOULD follow the guidance in [BCP38] to help prevent denial of
service attacks.
8. IANA Considerations
8.1. HTTP Method
This document will request IANA to register "CONNECT-IP" in the HTTP
Method Registry (IETF review) maintained at
<https://www.iana.org/assignments/http-methods>.
Chernyakhovsky, et al. Expires 28 February 2022 [Page 7]
Internet-Draft CONNECT-IP August 2021
+-------------+------+------------+---------------+
| Method Name | Safe | Idempotent | Reference |
+-------------+------+------------+---------------+
| CONNECT-IP | no | no | This document |
+-------------+------+------------+---------------+
8.2. Capsule Type Registrations
This document will request IANA to add the following values to the
"HTTP Capsule Types" registry created by [HTTP-DGRAM]:
+----------+---------------------+---------------------+---------------+
| Value | Type | Description | Reference |
+----------+---------------------+---------------------+---------------+
| 0xfff100 | ADDRESS_ASSIGN | Address Assignment | This document |
| 0xfff101 | ADDRESS_REQUEST | Address Request | This document |
| 0xfff105 | SHUTDOWN | Shutdown Reason | This document |
+----------+---------------------+---------------------+---------------+
9. References
9.1. Normative References
[BCP38] Ferguson, P. and D. Senie, "Network Ingress Filtering:
Defeating Denial of Service Attacks which employ IP Source
Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827,
May 2000, <https://www.rfc-editor.org/rfc/rfc2827>.
[H2] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015,
<https://www.rfc-editor.org/rfc/rfc7540>.
[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>.
Chernyakhovsky, et al. Expires 28 February 2022 [Page 8]
Internet-Draft CONNECT-IP August 2021
[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>.
[URI] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/rfc/rfc3986>.
[UTF8] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
2003, <https://www.rfc-editor.org/rfc/rfc3629>.
9.2. Informative References
[AUTH] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Authentication", RFC 7235,
DOI 10.17487/RFC7235, June 2014,
<https://www.rfc-editor.org/rfc/rfc7235>.
[IPSEC] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, DOI 10.17487/RFC4301,
December 2005, <https://www.rfc-editor.org/rfc/rfc4301>.
[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:
Chernyakhovsky, et al. Expires 28 February 2022 [Page 9]
Internet-Draft CONNECT-IP August 2021
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
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
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
Chernyakhovsky, et al. Expires 28 February 2022 [Page 10]
