Internet DRAFT - draft-pardue-httpbis-dont-be-clear
draft-pardue-httpbis-dont-be-clear
Network Working Group L. Pardue
Internet-Draft A. Ramine
Intended status: Standards Track Cloudflare
Expires: 17 September 2021 16 March 2021
Reserving the clear ALPN Protocol ID
draft-pardue-httpbis-dont-be-clear-00
Abstract
HTTP Alternative Services (Alt-Svc) are identified by a tuple of
Application-Protocol Layer Negotiation (ALPN) protocol identifier, a
host and a port. The wire format for Alt-Svc is defined in ABNF and
encodes this tuple or the keyword "clear", which has a special
meaning. This memo reserves the ALPN protocol identifier "clear" to
reduce the chances of accidental aliasing with the "clear" keyword.
Note to Readers
_RFC EDITOR: please remove this section before publication_
Source code and issues list for this draft can be found at
https://github.com/LPardue/draft-pardue-httpbis-dont-be-clear
(https://github.com/LPardue/draft-pardue-httpbis-dont-be-clear).
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 17 September 2021.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Conventions and Definitions . . . . . . . . . . . . . . . 2
2. Aliasing and Avoidance . . . . . . . . . . . . . . . . . . . 2
3. Security Considerations . . . . . . . . . . . . . . . . . . . 3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
4.1. Registration of "clear" Identification String . . . . . . 3
5. Normative References . . . . . . . . . . . . . . . . . . . . 3
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 4
1. Introduction
HTTP Alternative Services (Alt-Svc) [ALTSVC] are identified by a
tuple of Application-Protocol Layer Negotiation (ALPN) [ALPN]
protocol identifier, a host and a port. The wire format for Alt-Svc
is defined in ABNF and encodes this tuple or the keyword "clear",
which has a special meaning. This memo reserves the ALPN protocol
identifier "clear" to reduce the chances of accidental aliasing with
the "clear" keyword.
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.
2. Aliasing and Avoidance
[ALTSVC] Section 3 defines the Alt-Svc header field using ABNF. It
requires a custom parser, which introduces a possibility for custom
implementation errors. The Alt-Svc header field value can either be
the keyword "clear" - a special value that invalidates cached
alternative services, or a list of "alt-value", that includes an
encoded ALPN protocol identifier [ALPN]. There is a chance that
someone unwittingly defines the ALPN protocol identifier "clear" for
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genuine purposes but is unaware of the use of protocol identifiers in
Alternative Services. This could trigger Alt-Svc parser errors that
might lead to confusion between the keyword with the protocol
identifier use. Since the "clear" keyword has special meaning,
confusion might lead to detrimental effects.
To prevent unintended aliasing, this document registers the "clear"
ALPN protocol identifier. It relates to no actual application-layer
protocol, effectively reserving the code point and preventing any
unintended aliasing.
3. Security Considerations
Broken Alt-Svc header field parsers might confuse a "clear" keyword
with a "clear" ALPN protocol identifier. This could invalidate
Alternative Service cache state but a conformant client should fall
back safely as described in Section 2.4 of [ALTSVC].
4. IANA Considerations
4.1. Registration of "clear" Identification String
This document creates a new registration, "clear", in the
"Application-Layer Protocol Negotiation (ALPN) Protocol IDs" registry
established in [ALPN].
The "clear" string is a reserved value that does not identify any
protocol:
Protocol: Reserved
Identification Sequence: 0x63 0x6C 0x65 0x61 0x72 ("clear")
Specification: This document
5. Normative References
[ALPN] Friedl, S., Popov, A., Langley, A., and E. Stephan,
"Transport Layer Security (TLS) Application-Layer Protocol
Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301,
July 2014, <https://www.rfc-editor.org/rfc/rfc7301>.
[ALTSVC] Nottingham, M., McManus, P., and J. Reschke, "HTTP
Alternative Services", RFC 7838, DOI 10.17487/RFC7838,
April 2016, <https://www.rfc-editor.org/rfc/rfc7838>.
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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/rfc/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/rfc/rfc8174>.
Acknowledgments
Your name here.
Authors' Addresses
Lucas Pardue
Cloudflare
Email: lucaspardue.24.7@gmail.com
Anthony Ramine
Cloudflare
Email: nox@nox.paris
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