doc: Add RFC documents

1 files changed, 177 insertions, 0 deletions

diff --git a/doc/rfc/rfc9659.txt b/doc/rfc/rfc9659.txt
new file mode 100644
index 0000000..fea227c
--- /dev/null
+++ b/doc/rfc/rfc9659.txt
@@ -0,0 +1,177 @@
+
+
+
+
+Internet Engineering Task Force (IETF)                      N. Jaju, Ed.
+Request for Comments: 9659                                        Google
+Updates: 8878                                          W. F. Handte, Ed.
+Category: Informational                             Meta Platforms, Inc.
+ISSN: 2070-1721                                           September 2024
+
+
+              Window Sizing for Zstandard Content Encoding
+
+Abstract
+
+   Deployments of Zstandard, or "zstd", can use different window sizes
+   to limit memory usage during compression and decompression.  Some
+   browsers and user agents limit window sizes to mitigate memory usage
+   concerns, thereby causing interoperability issues.  This document
+   updates the window size limit in RFC 8878 from a recommendation to a
+   requirement in HTTP contexts.
+
+Status of This Memo
+
+   This document is not an Internet Standards Track specification; it is
+   published for informational purposes.
+
+   This document is a product of the Internet Engineering Task Force
+   (IETF).  It represents the consensus of the IETF community.  It has
+   received public review and has been approved for publication by the
+   Internet Engineering Steering Group (IESG).  Not all documents
+   approved by the IESG are candidates for any level of Internet
+   Standard; see Section 2 of RFC 7841.
+
+   Information about the current status of this document, any errata,
+   and how to provide feedback on it may be obtained at
+   https://www.rfc-editor.org/info/rfc9659.
+
+Copyright Notice
+
+   Copyright (c) 2024 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 Revised BSD License text as described in Section 4.e of the
+   Trust Legal Provisions and are provided without warranty as described
+   in the Revised BSD License.
+
+Table of Contents
+
+   1.  Introduction
+   2.  Conventions and Definitions
+   3.  Window Size
+   4.  Security Considerations
+   5.  IANA Considerations
+     5.1.  Content Encoding
+   6.  Normative References
+   Acknowledgments
+   Authors' Addresses
+
+1.  Introduction
+
+   Zstandard, or "zstd", specified in [RFC8878], is a lossless data
+   compression mechanism similar to gzip.  When used with HTTP, the
+   "zstd" content coding token signals to the decoder that the content
+   is Zstandard-compressed.
+
+   An important property of Zstandard-compressed content is its
+   Window_Size ([RFC8878], Section 3.1.1.1.2), which describes the
+   maximum distance for back-references and therefore how much of the
+   content must be kept in memory during decompression.
+
+   The minimum Window_Size is 1 KB.  The maximum Window_Size is (1<<41)
+   + 7*(1<<38) bytes, where "<<" denotes a bitwise left shift, which is
+   3.75 TB.  Larger Window_Size values tend to improve the compression
+   ratio but at the cost of increased memory usage.
+
+   To protect against unreasonable memory usage, some browsers and user
+   agents limit the maximum Window_Size they will handle.  This causes
+   failures to decode responses when the content is compressed with a
+   larger Window_Size than the recipient allows, leading to decreased
+   interoperability.
+
+   [RFC8878], Section 3.1.1.1.2 recommends that decoders support a
+   Window_Size of up to 8 MB, and that encoders not generate frames
+   using a Window_Size larger than 8 MB.  However, it imposes no
+   requirements.
+
+   This document updates [RFC8878] to enforce Window_Size limits on the
+   encoder and decoder for the "zstd" HTTP content coding.
+
+2.  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.
+
+3.  Window Size
+
+   To ensure interoperability, when using the "zstd" content coding,
+   decoders MUST support a Window_Size of up to and including 8 MB, and
+   encoders MUST NOT generate frames requiring a Window_Size larger than
+   8 MB (see Section 5.1).
+
+4.  Security Considerations
+
+   This document introduces no new security considerations beyond those
+   discussed in [RFC8878].
+
+   Note that decoders still need to take into account that they can
+   receive oversized frames that do not follow the window size limit
+   specified in this document and fail decoding when such invalid frames
+   are received.
+
+5.  IANA Considerations
+
+5.1.  Content Encoding
+
+   This document updates the following entry in the "HTTP Content Coding
+   Registry" in the "Hypertext Transfer Protocol (HTTP) Parameters"
+   registry group (https://www.iana.org/assignments/http-parameters):
+
+   Name:  zstd
+
+   Description:  A stream of bytes compressed using the Zstandard
+      protocol with a Window_Size of not more than 8 MB.
+
+   Reference:  This document and [RFC8878]
+
+6.  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,
+              <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>.
+
+   [RFC8878]  Collet, Y. and M. Kucherawy, Ed., "Zstandard Compression
+              and the 'application/zstd' Media Type", RFC 8878,
+              DOI 10.17487/RFC8878, February 2021,
+              <https://www.rfc-editor.org/info/rfc8878>.
+
+Acknowledgments
+
+   Zstandard was developed by Yann Collet.
+
+   The authors would like to thank Yann Collet, Klaus Post, Adam Rice,
+   and members of the Web Performance Working Group in the W3C for
+   collaborating on the window size issue and helping to formulate a
+   solution.
+
+Authors' Addresses
+
+   Nidhi Jaju (editor)
+   Google
+   Shibuya Stream, 3 Chome-21-3 Shibuya, Shibuya City, Tokyo
+   150-0002
+   Japan
+   Email: nidhijaju@google.com
+
+
+   W. Felix P. Handte (editor)
+   Meta Platforms, Inc.
+   380 W 33rd St
+   New York, NY 10001
+   United States of America
+   Email: felixh@meta.com