draft-ietf-httpbis-header-structure-04.txt   draft-ietf-httpbis-header-structure-05.txt 
HTTP M. Nottingham HTTP M. Nottingham
Internet-Draft Fastly Internet-Draft Fastly
Intended status: Standards Track P-H. Kamp Intended status: Standards Track P-H. Kamp
Expires: September 5, 2018 The Varnish Cache Project Expires: December 1, 2018 The Varnish Cache Project
March 4, 2018 May 30, 2018
Structured Headers for HTTP Structured Headers for HTTP
draft-ietf-httpbis-header-structure-04 draft-ietf-httpbis-header-structure-05
Abstract Abstract
This document describes a set of data types and parsing algorithms This document describes a set of data types and parsing algorithms
associated with them that are intended to make it easier and safer to associated with them that are intended to make it easier and safer to
define and handle HTTP header fields. It is intended for use by new define and handle HTTP header fields. It is intended for use by new
specifications of HTTP header fields as well as revisions of existing specifications of HTTP header fields as well as revisions of existing
header field specifications when doing so does not cause header field specifications when doing so does not cause
interoperability issues. interoperability issues.
skipping to change at page 1, line 34 skipping to change at page 1, line 34
Discussion of this draft takes place on the HTTP working group Discussion of this draft takes place on the HTTP working group
mailing list (ietf-http-wg@w3.org), which is archived at mailing list (ietf-http-wg@w3.org), which is archived at
https://lists.w3.org/Archives/Public/ietf-http-wg/ [1]. https://lists.w3.org/Archives/Public/ietf-http-wg/ [1].
Working Group information can be found at https://httpwg.github.io/ Working Group information can be found at https://httpwg.github.io/
[2]; source code and issues list for this draft can be found at [2]; source code and issues list for this draft can be found at
https://github.com/httpwg/http-extensions/labels/header-structure https://github.com/httpwg/http-extensions/labels/header-structure
[3]. [3].
Tests for implementations are collected at https://github.com/httpwg/
structured-header-tests [4].
Implementations are tracked at https://github.com/httpwg/wiki/wiki/
Structured-Headers [5].
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 5, 2018. This Internet-Draft will expire on December 1, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Notational Conventions . . . . . . . . . . . . . . . . . 4 1.1. Notational Conventions . . . . . . . . . . . . . . . . . 4
2. Specifying Structured Headers . . . . . . . . . . . . . . . . 4 2. Defining New Structured Headers . . . . . . . . . . . . . . . 4
3. Parsing Text into Structured Headers . . . . . . . . . . . . 5 3. Parsing Textual Header Fields . . . . . . . . . . . . . . . . 6
4. Structured Header Data Types . . . . . . . . . . . . . . . . 6 4. Structured Header Data Types . . . . . . . . . . . . . . . . 7
4.1. Dictionaries . . . . . . . . . . . . . . . . . . . . . . 6 4.1. Dictionaries . . . . . . . . . . . . . . . . . . . . . . 7
4.2. Lists . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.2. Lists . . . . . . . . . . . . . . . . . . . . . . . . . . 8
4.3. Parameterised Lists . . . . . . . . . . . . . . . . . . . 9 4.3. Parameterised Lists . . . . . . . . . . . . . . . . . . . 9
4.4. Items . . . . . . . . . . . . . . . . . . . . . . . . . . 11 4.4. Items . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.5. Integers . . . . . . . . . . . . . . . . . . . . . . . . 11 4.5. Integers . . . . . . . . . . . . . . . . . . . . . . . . 12
4.6. Floats . . . . . . . . . . . . . . . . . . . . . . . . . 12 4.6. Floats . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.7. Strings . . . . . . . . . . . . . . . . . . . . . . . . . 13 4.7. Strings . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.8. Identifiers . . . . . . . . . . . . . . . . . . . . . . . 15 4.8. Identifiers . . . . . . . . . . . . . . . . . . . . . . . 15
4.9. Binary Content . . . . . . . . . . . . . . . . . . . . . 16 4.9. Binary Content . . . . . . . . . . . . . . . . . . . . . 16
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
6. Security Considerations . . . . . . . . . . . . . . . . . . . 17 6. Security Considerations . . . . . . . . . . . . . . . . . . . 17
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 17 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
7.1. Normative References . . . . . . . . . . . . . . . . . . 17 7.1. Normative References . . . . . . . . . . . . . . . . . . 18
7.2. Informative References . . . . . . . . . . . . . . . . . 18 7.2. Informative References . . . . . . . . . . . . . . . . . 18
7.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 18 7.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Appendix A. Changes . . . . . . . . . . . . . . . . . . . . . . 18 Appendix A. Changes . . . . . . . . . . . . . . . . . . . . . . 19
A.1. Since draft-ietf-httpbis-header-structure-03 . . . . . . 18 A.1. Since draft-ietf-httpbis-header-structure-04 . . . . . . 19
A.2. Since draft-ietf-httpbis-header-structure-02 . . . . . . 18 A.2. Since draft-ietf-httpbis-header-structure-03 . . . . . . 19
A.3. Since draft-ietf-httpbis-header-structure-01 . . . . . . 19 A.3. Since draft-ietf-httpbis-header-structure-02 . . . . . . 19
A.4. Since draft-ietf-httpbis-header-structure-00 . . . . . . 19 A.4. Since draft-ietf-httpbis-header-structure-01 . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19 A.5. Since draft-ietf-httpbis-header-structure-00 . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20
1. Introduction 1. Introduction
Specifying the syntax of new HTTP header fields is an onerous task; Specifying the syntax of new HTTP header fields is an onerous task;
even with the guidance in [RFC7231], Section 8.3.1, there are many even with the guidance in [RFC7231], Section 8.3.1, there are many
decisions - and pitfalls - for a prospective HTTP header field decisions - and pitfalls - for a prospective HTTP header field
author. author.
Once a header field is defined, bespoke parsers for it often need to Once a header field is defined, bespoke parsers for it often need to
be written, because each header has slightly different handling of be written, because each header has slightly different handling of
what looks like common syntax. what looks like common syntax.
This document introduces structured HTTP header field values This document introduces a set of common data structures for use in
(hereafter, Structured Headers) to address these problems. HTTP header field values to address these problems. In particular,
Structured Headers define a generic, abstract model for header field it defines a generic, abstract model for header field values, along
values, along with a concrete serialisation for expressing that model with a concrete serialisation for expressing that model in textual
in textual HTTP headers, as used by HTTP/1 [RFC7230] and HTTP/2 HTTP headers, as used by HTTP/1 [RFC7230] and HTTP/2 [RFC7540].
[RFC7540].
HTTP headers that are defined as Structured Headers use the types HTTP headers that are defined as "Structured Headers" use the types
defined in this specification to define their syntax and basic defined in this specification to define their syntax and basic
handling rules, thereby simplifying both their definition and handling rules, thereby simplifying both their definition and
parsing. parsing.
Additionally, future versions of HTTP can define alternative Additionally, future versions of HTTP can define alternative
serialisations of the abstract model of Structured Headers, allowing serialisations of the abstract model of these structures, allowing
headers that use it to be transmitted more efficiently without being headers that use it to be transmitted more efficiently without being
redefined. redefined.
Note that it is not a goal of this document to redefine the syntax of Note that it is not a goal of this document to redefine the syntax of
existing HTTP headers; the mechanisms described herein are only existing HTTP headers; the mechanisms described herein are only
intended to be used with headers that explicitly opt into them. intended to be used with headers that explicitly opt into them.
To specify a header field that uses Structured Headers, see To specify a header field that is a Structured Header, see Section 2.
Section 2.
Section 4 defines a number of abstract data types that can be used in Section 4 defines a number of abstract data types that can be used in
Structured Headers. Dictionaries and lists are only usable at the Structured Headers. Dictionaries and lists are only usable at the
"top" level, while the remaining types can be specified appear at the "top" level, while the remaining types can be specified appear at the
top level or inside those structures. top level or inside those structures.
Those abstract types can be serialised into textual headers - such as Those abstract types can be serialised into textual headers - such as
those used in HTTP/1 and HTTP/2 - using the algorithms described in those used in HTTP/1 and HTTP/2 - using the algorithms described in
Section 3. Section 3.
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The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
This document uses the Augmented Backus-Naur Form (ABNF) notation of This document uses the Augmented Backus-Naur Form (ABNF) notation of
[RFC5234], including the DIGIT, ALPHA and DQUOTE rules from that [RFC5234], including the DIGIT, ALPHA and DQUOTE rules from that
document. It also includes the OWS rule from [RFC7230]. document. It also includes the OWS rule from [RFC7230].
2. Specifying Structured Headers This document uses algorithms to specify normative parsing
behaviours, and ABNF to illustrate the on-wire format expected.
Implementations MUST follow the normative algorithms, but MAY vary in
implementation so as the behaviours are indistinguishable from
specified behaviour. If there is disagreement between the algorithms
and ABNF, the specified algorithms take precedence.
A HTTP header that uses Structured Headers need to be defined to do 2. Defining New Structured Headers
so explicitly; recipients and generators need to know that the
requirements of this document are in effect. The simplest way to do A HTTP header that uses the structures in this specification need to
that is by referencing this document in its definition. be defined to do so explicitly; recipients and generators need to
know that the requirements of this document are in effect. The
simplest way to do that is by referencing this document in its
definition.
The field's definition will also need to specify the field-value's The field's definition will also need to specify the field-value's
allowed syntax, in terms of the types described in Section 4, along allowed syntax, in terms of the types described in Section 4, along
with their associated semantics. with their associated semantics.
A header field definition cannot relax or otherwise modify the A header field definition cannot relax or otherwise modify the
requirements of this specification; doing so would preclude handling requirements of this specification, or change the nature of its data
by generic software. structures; doing so would preclude handling by generic software.
However, header field authors are encouraged to clearly state However, header field authors are encouraged to clearly state
additional constraints upon the syntax, as well as the consequences additional constraints upon the syntax, as well as the consequences
when those constraints are violated. Such additional constraints when those constraints are violated. When Structured Headers parsing
could include additional structure (e.g., a list of URLs [RFC3986] fails, the header is discarded (see Section 3); in most situations,
inside a string) that cannot be expressed using the primitives header-specific constraints should do likewise.
defined here.
Such constraints could include additional structure inside those
defined here (e.g., a list of URLs [RFC3986] inside a string).
For example: For example:
# FooExample Header # Foo-Example Header
The FooExample HTTP header field conveys a list of integers about how The Foo-Example HTTP header field conveys information about how
much Foo the sender has. much Foo the message has.
FooExample is a Structured header [RFCxxxx]. Its value MUST be a Foo-Example is a Structured Header [RFCxxxx]. Its value MUST be a
dictionary ([RFCxxxx], Section Y.Y). dictionary ([RFCxxxx], Section Y.Y).
The dictionary MUST contain: The dictionary MUST contain:
* Exactly one member whose key is "foo", and whose value is an integer * Exactly one member whose key is "foo", and whose value is an
([RFCxxxx], Section Y.Y), indicating the number of foos in integer ([RFCxxxx], Section Y.Y), indicating the number of foos in
the message. the message.
* Exactly one member whose key is "barUrls", and whose value is a string * Exactly one member whose key is "barUrls", and whose value is a
([RFCxxxx], Section Y.Y), conveying the Bar URLs for the message. string ([RFCxxxx], Section Y.Y), conveying the Bar URLs for the
See below for processing requirements. message. See below for processing requirements.
If the parsed header field does not contain both, it MUST be ignored. If the parsed header field does not contain both, it MUST be ignored.
"foo" MUST be between 0 and 10, inclusive; other values MUST be ignored. "foo" MUST be between 0 and 10, inclusive; other values MUST cause
the header to be ignored.
"barUrls" contains a space-separated list of URI-references ([RFC3986], "barUrls" contains a space-separated list of URI-references
Section 4.1): ([RFC3986], Section 4.1):
barURLs = URI-reference *( 1*SP URI-reference ) barURLs = URI-reference *( 1*SP URI-reference )
If a member of barURLs is not a valid URI-reference, it MUST be ignored. If a member of barURLs is not a valid URI-reference, it MUST cause
that value to be ignored.
If a member of barURLs is a relative reference ([RFC3986], Section 4.2), If a member of barURLs is a relative reference ([RFC3986],
it MUST be resolved ([RFC3986], Section 5) before being used. Section 4.2), it MUST be resolved ([RFC3986], Section 5) before being
used.
Note that empty header field values are not allowed by the syntax, This specification defines minimums for the length or number of
and therefore parsing for them will fail. various structures supported by Structured Headers implementations.
It does not specify maximum sizes in most cases, but header authors
should be aware that HTTP implementations do impose various limits on
the size of individual header fields, the total number of fields,
and/or the size of the entire header block.
3. Parsing Text into Structured Headers Note that specifications using Structured Headers do not re-specify
its ABNF or parsing algorithms; instead, they should be specified in
terms of its abstract data structures.
Also, empty header field values are not allowed, and therefore
parsing for them will fail.
3. Parsing Textual Header Fields
When a receiving implementation parses textual HTTP header fields When a receiving implementation parses textual HTTP header fields
(e.g., in HTTP/1 or HTTP/2) that are known to be Structured Headers, (e.g., in HTTP/1 or HTTP/2) that are known to be Structured Headers,
it is important that care be taken, as there are a number of edge it is important that care be taken, as there are a number of edge
cases that can cause interoperability or even security problems. cases that can cause interoperability or even security problems.
This section specifies the algorithm for doing so. This section specifies the algorithm for doing so.
Given an ASCII string input_string that represents the chosen Given an ASCII string input_string that represents the chosen
header's field-value, return the parsed header value. When header's field-value, and header_type, one of "dictionary", "list",
generating input_string, parsers MUST combine all instances of the "param-list", or "item", return the parsed header value.
target header field into one comma-separated field-value, as per
[RFC7230], Section 3.2.2; this assures that the header is processed
correctly.
1. Discard any leading OWS from input_string. 1. Discard any leading OWS from input_string.
2. If the field-value is defined to be a dictionary, let output be 2. If header_type is "dictionary", let output be the result of
the result of Parsing a Dictionary from Text (Section 4.1.1). Parsing a Dictionary from Text (Section 4.1.1).
3. If the field-value is defined to be a list, let output be the 3. If header_type is "list", let output be the result of Parsing a
result of Parsing a List from Text (Section 4.2.1). List from Text (Section 4.2.1).
4. If the field-value is defined to be a parameterised list, let 4. If header_type is "param-list", let output be the result of
output be the result of Parsing a Parameterised List from Text Parsing a Parameterised List from Text (Section 4.3.1).
(Section 4.3.1).
5. Otherwise, let output be the result of Parsing an Item from Text 5. Otherwise, let output be the result of Parsing an Item from Text
(Section 4.4.1). (Section 4.4.1).
6. Discard any leading OWS from input_string. 6. Discard any leading OWS from input_string.
7. If input_string is not empty, fail parsing. 7. If input_string is not empty, fail parsing.
8. Otherwise, return output. 8. Otherwise, return output.
Note that in the case of lists, parameterised lists and dictionaries, When generating input_string, parsers MUST combine all instances of
this has the effect of coalescing all of the values for that field. the target header field into one comma-separated field-value, as per
However, for singular items, parsing will fail if more than instance [RFC7230], Section 3.2.2; this assures that the header is processed
of that header field is present. correctly.
If parsing fails, the entire header field's value MUST be discarded. For Lists, Parameterised Lists and Dictionaries, this has the effect
This is intentionally strict, to improve interoperability and safety, of correctly concatenating all instances of the header field.
and specifications referencing this document MUST NOT loosen this
requirement. Strings can but SHOULD NOT be split across multiple header instances,
because comma(s) inserted upon combination will become part of the
string output by the parser.
Integers, Floats and Binary Content cannot be split across multiple
headers because the inserted commas will cause parsing to fail.
If parsing fails - including when calling another algorithm - the
entire header field's value MUST be discarded. This is intentionally
strict, to improve interoperability and safety, and specifications
referencing this document cannot loosen this requirement.
Note that this has the effect of discarding any header field with Note that this has the effect of discarding any header field with
non-ASCII characters in input_string. non-ASCII characters in input_string.
4. Structured Header Data Types 4. Structured Header Data Types
This section defines the abstract value types that can be composed This section defines the abstract value types that can be composed
into Structured Headers, along with the textual HTTP serialisations into Structured Headers, along with the textual HTTP serialisations
of them. of them.
4.1. Dictionaries 4.1. Dictionaries
Dictionaries are unordered maps of key-value pairs, where the keys Dictionaries are unordered maps of key-value pairs, where the keys
are identifiers (Section 4.8) and the values are items (Section 4.4). are identifiers (Section 4.8) and the values are items (Section 4.4).
There can be between 1 and 1024 members, and keys are required to be There can be one or more members, and keys are required to be unique.
unique.
In the textual HTTP serialisation, keys and values are separated by In the textual HTTP serialisation, keys and values are separated by
"=" (without whitespace), and key/value pairs are separated by a "=" (without whitespace), and key/value pairs are separated by a
comma with optional whitespace. Duplicate keys MUST cause parsing to comma with optional whitespace. Duplicate keys MUST cause parsing to
fail. fail.
dictionary = dictionary_member *1023( OWS "," OWS dictionary_member ) dictionary = dict-member *( OWS "," OWS dict-member )
dictionary_member = identifier "=" item dict-member = identifier "=" item
For example, a header field whose value is defined as a dictionary For example, a header field whose value is defined as a dictionary
could look like: could look like:
ExampleDictHeader: foo=1.23, en="Applepie", da=*w4ZibGV0w6ZydGUK Example-DictHeader: foo=1.23, en="Applepie", da=*w4ZibGV0w6ZydGUK=*
Typically, a header field specification will define the semantics of Typically, a header field specification will define the semantics of
individual keys, as well as whether their presence is required or individual keys, as well as whether their presence is required or
optional. Recipients MUST ignore keys that are undefined or unknown, optional. Recipients MUST ignore keys that are undefined or unknown,
unless the header field's specification specifically disallows them. unless the header field's specification specifically disallows them.
Parsers MUST support dictionaries containing at least 1024 key/value
pairs.
4.1.1. Parsing a Dictionary from Text 4.1.1. Parsing a Dictionary from Text
Given an ASCII string input_string, return a mapping of (identifier, Given an ASCII string input_string, return a mapping of (identifier,
item). input_string is modified to remove the parsed value. item). input_string is modified to remove the parsed value.
1. Let dictionary be an empty, unordered mapping. 1. Let dictionary be an empty, unordered mapping.
2. While input_string is not empty: 2. While input_string is not empty:
1. Let this_key be the result of running Parse Identifier from 1. Let this_key be the result of running Parse Identifier from
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2. If dictionary already contains this_key, fail parsing. 2. If dictionary already contains this_key, fail parsing.
3. Consume a "=" from input_string; if none is present, fail 3. Consume a "=" from input_string; if none is present, fail
parsing. parsing.
4. Let this_value be the result of running Parse Item from Text 4. Let this_value be the result of running Parse Item from Text
(Section 4.4.1) with input_string. (Section 4.4.1) with input_string.
5. Add key this_key with value this_value to dictionary. 5. Add key this_key with value this_value to dictionary.
6. If dictionary has more than 1024 members, fail parsing. 6. Discard any leading OWS from input_string.
7. Discard any leading OWS from input_string.
8. If input_string is empty, return dictionary. 7. If input_string is empty, return dictionary.
9. Consume a COMMA from input_string; if no comma is present, 8. Consume a COMMA from input_string; if no comma is present,
fail parsing. fail parsing.
10. Discard any leading OWS from input_string. 9. Discard any leading OWS from input_string.
11. If input_string is empty, fail parsing.
3. If dictionary is empty, fail parsing. 10. If input_string is empty, fail parsing.
4. Return dictionary. 3. No structured data has been found; fail parsing.
4.2. Lists 4.2. Lists
Lists are arrays of items (Section 4.4) with one to 1024 members. Lists are arrays of items (Section 4.4) with one or more members.
In the textual HTTP serialisation, each member is separated by a In the textual HTTP serialisation, each member is separated by a
comma and optional whitespace. comma and optional whitespace.
list = list_member 0*1023( OWS "," OWS list_member ) list = list-member *( OWS "," OWS list-member )
list_member = item list-member = item
For example, a header field whose value is defined as a list of For example, a header field whose value is defined as a list of
identifiers could look like: strings could look like:
ExampleIdListHeader: foo, bar, baz_45 Example-StrListHeader: "foo", "bar", "It was the best of times."
Parsers MUST support lists containing at least 1024 members.
4.2.1. Parsing a List from Text 4.2.1. Parsing a List from Text
Given an ASCII string input_string, return a list of items. Given an ASCII string input_string, return a list of items.
input_string is modified to remove the parsed value. input_string is modified to remove the parsed value.
1. Let items be an empty array. 1. Let items be an empty array.
2. While input_string is not empty: 2. While input_string is not empty:
1. Let item be the result of running Parse Item from Text 1. Let item be the result of running Parse Item from Text
(Section 4.4.1) with input_string. (Section 4.4.1) with input_string.
2. Append item to items. 2. Append item to items.
3. If items has more than 1024 members, fail parsing. 3. Discard any leading OWS from input_string.
4. Discard any leading OWS from input_string.
5. If input_string is empty, return items. 4. If input_string is empty, return items.
6. Consume a COMMA from input_string; if no comma is present, 5. Consume a COMMA from input_string; if no comma is present,
fail parsing. fail parsing.
7. Discard any leading OWS from input_string. 6. Discard any leading OWS from input_string.
8. If input_string is empty, fail parsing.
3. If items is empty, fail parsing. 7. If input_string is empty, fail parsing.
4. Return items. 3. No structured data has been found; fail parsing.
4.3. Parameterised Lists 4.3. Parameterised Lists
Parameterised Lists are arrays of a parameterised identifiers with 1 Parameterised Lists are arrays of a parameterised identifiers.
to 256 members.
A parameterised identifier is an identifier (Section 4.8) with up to A parameterised identifier is an identifier (Section 4.8) with an
256 parameters, each parameter having a identifier and an optional optional set of parameters, each parameter having a identifier and an
value that is an item (Section 4.4). Ordering between parameters is optional value that is an item (Section 4.4). Ordering between
not significant, and duplicate parameters MUST cause parsing to fail. parameters is not significant, and duplicate parameters MUST cause
parsing to fail.
In the textual HTTP serialisation, each parameterised identifier is In the textual HTTP serialisation, each parameterised identifier is
separated by a comma and optional whitespace. Parameters are separated by a comma and optional whitespace. Parameters are
delimited from each other using semicolons (";"), and equals ("=") delimited from each other using semicolons (";"), and equals ("=")
delimits the parameter name from its value. delimits the parameter name from its value.
param_list = param_id 0*255( OWS "," OWS param_id ) param-list = param-id *( OWS "," OWS param-id )
param_id = identifier 0*256( OWS ";" OWS identifier [ "=" item ] ) param-id = identifier *( OWS ";" OWS identifier [ "=" item ] )
For example, For example,
ExampleParamListHeader: abc_123;a=1;b=2; c, def_456, ghi;q="19";r=foo Example-ParamListHeader: abc_123;a=1;b=2; c, def_456, ghi;q="19";r=foo
Parsers MUST support parameterised lists containing at least 1024
members, and support members with at least 256 parameters.
4.3.1. Parsing a Parameterised List from Text 4.3.1. Parsing a Parameterised List from Text
Given an ASCII string input_string, return a list of parameterised Given an ASCII string input_string, return a list of parameterised
identifiers. input_string is modified to remove the parsed value. identifiers. input_string is modified to remove the parsed value.
1. Let items be an empty array. 1. Let items be an empty array.
2. While input_string is not empty: 2. While input_string is not empty:
1. Let item be the result of running Parse Parameterised 1. Let item be the result of running Parse Parameterised
Identifier from Text (Section 4.3.2) with input_string. Identifier from Text (Section 4.3.2) with input_string.
2. Append item to items. 2. Append item to items.
3. If items has more than 256 members, fail parsing. 3. Discard any leading OWS from input_string.
4. Discard any leading OWS from input_string.
5. If input_string is empty, return items. 4. If input_string is empty, return items.
6. Consume a COMMA from input_string; if no comma is present, 5. Consume a COMMA from input_string; if no comma is present,
fail parsing. fail parsing.
7. Discard any leading OWS from input_string. 6. Discard any leading OWS from input_string.
8. If input_string is empty, fail parsing.
3. If items is empty, fail parsing. 7. If input_string is empty, fail parsing.
4. Return items. 3. No structured data has been found; fail parsing.
4.3.2. Parsing a Parameterised Identifier from Text 4.3.2. Parsing a Parameterised Identifier from Text
Given an ASCII string input_string, return a identifier with an Given an ASCII string input_string, return a identifier with an
mapping of parameters. input_string is modified to remove the parsed mapping of parameters. input_string is modified to remove the parsed
value. value.
1. Let primary_identifier be the result of Parsing a Identifier from 1. Let primary_identifier be the result of Parsing a Identifier from
Text (Section 4.8.1) from input_string. Text (Section 4.8.1) from input_string.
2. Let parameters be an empty, unordered mapping. 2. Let parameters be an empty, unordered mapping.
3. In a loop: 3. In a loop:
1. Discard any leading OWS from input_string. 1. Discard any leading OWS from input_string.
2. If the first character of input_string is not ";", exit the
loop.
3. Consume a ";" character from the beginning of input_string. 2. If the first character of input_string is not ";", exit the
loop.
4. Discard any leading OWS from input_string. 3. Consume a ";" character from the beginning of input_string.
5. let param_name be the result of Parsing a Identifier from 4. Discard any leading OWS from input_string.
Text (Section 4.8.1) from input_string.
6. If param_name is already present in parameters, fail 5. let param_name be the result of Parsing a Identifier from
parsing. Text (Section 4.8.1) from input_string.
7. Let param_value be a null value. 6. If param_name is already present in parameters, fail parsing.
8. If the first character of input_string is "=": 7. Let param_value be a null value.
1. Consume the "=" character at the beginning of 8. If the first character of input_string is "=":
input_string.
2. Let param_value be the result of Parsing an Item from 1. Consume the "=" character at the beginning of
Text (Section 4.4.1) from input_string. input_string.
9. If parameters has more than 255 members, fail parsing. 2. Let param_value be the result of Parsing an Item from
Text (Section 4.4.1) from input_string.
10. Add param_name to parameters with the value param_value. 9. Insert (param_name, param_value) into parameters.
4. Return the tuple (primary_identifier, parameters). 4. Return the tuple (primary_identifier, parameters).
4.4. Items 4.4. Items
An item is can be a integer (Section 4.5), float (Section 4.6), An item is can be a integer (Section 4.5), float (Section 4.6),
string (Section 4.7), identifier (Section 4.8) or binary content string (Section 4.7), or binary content (Section 4.9).
(Section 4.9).
item = integer / float / string / identifier / binary item = integer / float / string / binary
4.4.1. Parsing an Item from Text 4.4.1. Parsing an Item from Text
Given an ASCII string input_string, return an item. input_string is Given an ASCII string input_string, return an item. input_string is
modified to remove the parsed value. modified to remove the parsed value.
1. Discard any leading OWS from input_string. 1. Discard any leading OWS from input_string.
2. If the first character of input_string is a "-" or a DIGIT, 2. If the first character of input_string is a "-" or a DIGIT,
process input_string as a number (Section 4.5.1) and return the process input_string as a number (Section 4.5.1) and return the
result. result.
3. If the first character of input_string is a DQUOTE, process 3. If the first character of input_string is a DQUOTE, process
input_string as a string (Section 4.7.1) and return the result. input_string as a string (Section 4.7.1) and return the result.
4. If the first character of input_string is "*", process 4. If the first character of input_string is "*", process
input_string as binary content (Section 4.9.1) and return the input_string as binary content (Section 4.9.1) and return the
result. result.
5. If the first character of input_string is an lcalpha, process 5. Otherwise, fail parsing.
input_string as a identifier (Section 4.8.1) and return the
result.
6. Otherwise, fail parsing.
4.5. Integers 4.5. Integers
Abstractly, integers have a range of -9,223,372,036,854,775,808 to Abstractly, integers have a range of -9,223,372,036,854,775,808 to
9,223,372,036,854,775,807 inclusive (i.e., a 64-bit signed integer). 9,223,372,036,854,775,807 inclusive (i.e., a 64-bit signed integer).
integer = ["-"] 1*19DIGIT integer = ["-"] 1*19DIGIT
Parsers that encounter an integer outside the range defined above Parsers that encounter an integer outside the range defined above
MUST fail parsing. Therefore, the value "9223372036854775808" would MUST fail parsing. Therefore, the value "9223372036854775808" would
be invalid. Likewise, values that do not conform to the ABNF above be invalid. Likewise, values that do not conform to the ABNF above
are invalid, and MUST fail parsing. are invalid, and MUST fail parsing.
For example, a header whose value is defined as a integer could look For example, a header whose value is defined as a integer could look
like: like:
ExampleIntegerHeader: 42 Example-IntegerHeader: 42
4.5.1. Parsing a Number from Text 4.5.1. Parsing a Number from Text
NOTE: This algorithm parses both Integers and Floats Section 4.6, and NOTE: This algorithm parses both Integers and Floats Section 4.6, and
returns the corresponding structure. returns the corresponding structure.
1. If the first character of input_string is not "-" or a DIGIT, 1. Let type be "integer".
fail parsing.
2. Let input_number be the result of consuming input_string up to 2. Let sign be 1.
(but not including) the first character that is not in DIGIT,
"-", and ".".
3. If input_number contains ".", parse it as a floating point number 3. Let input_number be an empty string.
and let output_number be the result.
4. Otherwise, parse input_number as an integer and let output_number 4. If the first character of input_string is "-", remove it from
be the result. input_string and set sign to -1.
5. Return output_number. 5. If input_string is empty, fail parsing.
6. If the first character of input_string is not a DIGIT, fail
parsing.
7. While input_string is not empty:
1. Let char be the result of removing the first character of
input_string.
2. If char is a DIGIT, append it to input_number.
3. Else, if type is "integer" and char is ".", append char to
input_number and set type to "float".
4. Otherwise, fail parsing.
5. If type is "integer" and input_number contains more than 19
characters, fail parsing.
6. If type is "float" and input_number contains more than 16
characters, fail parsing.
8. If type is "integer", parse input_number as an integer and let
output_number be the result.
9. Otherwise:
1. If the final character of input_number is ".", fail parsing.
2. Parse input_number as a float and let output_number be the
result.
10. Return the product of output_number and sign.
4.6. Floats 4.6. Floats
Abstractly, floats are integers with a fractional part. They have a Abstractly, floats are integers with a fractional part, that can be
maximum of fifteen digits available to be used in both of the parts, stored as IEEE 754 double precision numbers (binary64) ([IEEE754]).
as reflected in the ABNF below; this allows them to be stored as IEEE
754 double precision numbers (binary64) ([IEEE754]).
The textual HTTP serialisation of floats allows a maximum of fifteen The textual HTTP serialisation of floats allows a maximum of fifteen
digits between the integer and fractional part, with at least one digits between the integer and fractional part, with at least one
required on each side, along with an optional "-" indicating negative required on each side, along with an optional "-" indicating negative
numbers. numbers.
float = ["-"] ( float = ["-"] (
DIGIT "." 1*14DIGIT / DIGIT "." 1*14DIGIT /
2DIGIT "." 1*13DIGIT / 2DIGIT "." 1*13DIGIT /
3DIGIT "." 1*12DIGIT / 3DIGIT "." 1*12DIGIT /
skipping to change at page 13, line 27 skipping to change at page 14, line 8
12DIGIT "." 1*3DIGIT / 12DIGIT "." 1*3DIGIT /
13DIGIT "." 1*2DIGIT / 13DIGIT "." 1*2DIGIT /
14DIGIT "." 1DIGIT ) 14DIGIT "." 1DIGIT )
Values that do not conform to the ABNF above are invalid, and MUST Values that do not conform to the ABNF above are invalid, and MUST
fail parsing. fail parsing.
For example, a header whose value is defined as a float could look For example, a header whose value is defined as a float could look
like: like:
ExampleFloatHeader: 4.5 Example-FloatHeader: 4.5
See Section 4.5.1 for the parsing algorithm for floats. See Section 4.5.1 for the parsing algorithm for floats.
4.7. Strings 4.7. Strings
Abstractly, strings are up to 1024 printable ASCII [RFC0020] Abstractly, strings are zero or more printable ASCII [RFC0020]
characters (i.e., the range 0x20 to 0x7E). Note that this excludes characters (i.e., the range 0x20 to 0x7E). Note that this excludes
tabs, newlines and carriage returns. tabs, newlines, carriage returns, etc.
The textual HTTP serialisation of strings uses a backslash ("\") to The textual HTTP serialisation of strings uses a backslash ("\") to
escape double quotes and backslashes in strings. escape double quotes and backslashes in strings.
string = DQUOTE 0*1024(char) DQUOTE string = DQUOTE *(chr) DQUOTE
char = unescaped / escape ( DQUOTE / "\" ) chr = unescaped / escaped
unescaped = %x20-21 / %x23-5B / %x5D-7E unescaped = %x20-21 / %x23-5B / %x5D-7E
escape = "\" escaped = "\" ( DQUOTE / "\" )
For example, a header whose value is defined as a string could look For example, a header whose value is defined as a string could look
like: like:
ExampleStringHeader: "hello world" Example-StringHeader: "hello world"
Note that strings only use DQUOTE as a delimiter; single quotes do Note that strings only use DQUOTE as a delimiter; single quotes do
not delimit strings. Furthermore, only DQUOTE and "\" can be not delimit strings. Furthermore, only DQUOTE and "\" can be
escaped; other sequences MUST cause parsing to fail. escaped; other sequences MUST cause parsing to fail.
Unicode is not directly supported in Structured Headers, because it Unicode is not directly supported in this document, because it causes
causes a number of interoperability issues, and - with few exceptions a number of interoperability issues, and - with few exceptions -
- header values do not require it. header values do not require it.
When it is necessary for a field value to convey non-ASCII string When it is necessary for a field value to convey non-ASCII string
content, binary content (Section 4.9) SHOULD be specified, along with content, binary content (Section 4.9) SHOULD be specified, along with
a character encoding (preferably, UTF-8). a character encoding (preferably, UTF-8).
Parsers MUST support strings with at least 1024 characters.
4.7.1. Parsing a String from Text 4.7.1. Parsing a String from Text
Given an ASCII string input_string, return an unquoted string. Given an ASCII string input_string, return an unquoted string.
input_string is modified to remove the parsed value. input_string is modified to remove the parsed value.
1. Let output_string be an empty string. 1. Let output_string be an empty string.
2. If the first character of input_string is not DQUOTE, fail 2. If the first character of input_string is not DQUOTE, fail
parsing. parsing.
skipping to change at page 14, line 47 skipping to change at page 15, line 32
character of input_string. character of input_string.
2. If next_char is not DQUOTE or "\", fail parsing. 2. If next_char is not DQUOTE or "\", fail parsing.
3. Append next_char to output_string. 3. Append next_char to output_string.
3. Else, if char is DQUOTE, return output_string. 3. Else, if char is DQUOTE, return output_string.
4. Else, append char to output_string. 4. Else, append char to output_string.
5. If output_string contains more than 1024 characters, fail
parsing.
5. Otherwise, fail parsing. 5. Otherwise, fail parsing.
4.8. Identifiers 4.8. Identifiers
Identifiers are short (up to 256 characters) textual identifiers; Identifiers are short textual identifiers; their abstract model is
their abstract model is identical to their expression in the textual identical to their expression in the textual HTTP serialisation.
HTTP serialisation. Parsers MUST support identifiers with at least 64 characters.
identifier = lcalpha *255( lcalpha / DIGIT / "_" / "-"/ "*" / "/" ) identifier = lcalpha *( lcalpha / DIGIT / "_" / "-"/ "*" / "/" )
lcalpha = %x61-7A ; a-z lcalpha = %x61-7A ; a-z
Note that identifiers can only contain lowercase letters. Note that identifiers can only contain lowercase letters.
For example, a header whose value is defined as a identifier could
look like:
ExampleIdHeader: foo/bar
4.8.1. Parsing a Identifier from Text 4.8.1. Parsing a Identifier from Text
Given an ASCII string input_string, return a identifier. input_string Given an ASCII string input_string, return a identifier. input_string
is modified to remove the parsed value. is modified to remove the parsed value.
1. If the first character of input_string is not lcalpha, fail 1. If the first character of input_string is not lcalpha, fail
parsing. parsing.
2. Let output_string be an empty string. 2. Let output_string be an empty string.
skipping to change at page 15, line 44 skipping to change at page 16, line 20
input_string. input_string.
2. If char is not one of lcalpha, DIGIT, "_", "-", "*" or "/": 2. If char is not one of lcalpha, DIGIT, "_", "-", "*" or "/":
1. Prepend char to input_string. 1. Prepend char to input_string.
2. Return output_string. 2. Return output_string.
3. Append char to output_string. 3. Append char to output_string.
4. If output_string contains more than 256 characters, fail
parsing.
4. Return output_string. 4. Return output_string.
4.9. Binary Content 4.9. Binary Content
Arbitrary binary content up to 16384 bytes in size can be conveyed in Arbitrary binary content can be conveyed in Structured Headers.
Structured Headers.
The textual HTTP serialisation encodes the data using Base 64 The textual HTTP serialisation encodes the data using Base 64
Encoding [RFC4648], Section 4, and surrounds it with a pair of Encoding [RFC4648], Section 4, and surrounds it with a pair of
asterisks ("*") to delimit from other content. asterisks ("*") to delimit from other content.
The encoded data is required to be padded with "=", as per [RFC4648], The encoded data is required to be padded with "=", as per [RFC4648],
Section 3.2. It is RECOMMENDED that parsers reject encoded data that Section 3.2. It is RECOMMENDED that parsers reject encoded data that
is not properly padded, although this might not be possible with some is not properly padded, although this might not be possible with some
base64 implementations. base64 implementations.
Likewise, encoded data is required to have pad bits set to zero, as Likewise, encoded data is required to have pad bits set to zero, as
per [RFC4648], Section 3.5. It is RECOMMENDED that parsers fail on per [RFC4648], Section 3.5. It is RECOMMENDED that parsers fail on
encoded data that has non-zero pad bits, although this might not be encoded data that has non-zero pad bits, although this might not be
possible with some base64 implementations. possible with some base64 implementations.
This specification does not relax the requirements in [RFC4648], This specification does not relax the requirements in [RFC4648],
Section 3.1 and 3.3; therefore, parsers MUST fail on characters Section 3.1 and 3.3; therefore, parsers MUST fail on characters
outside the base64 alphabet, and on line feeds in encoded data. outside the base64 alphabet, and on line feeds in encoded data.
binary = "*" 0*21846(base64) "*" binary = "*" *(base64) "*"
base64 = ALPHA / DIGIT / "+" / "/" / "=" base64 = ALPHA / DIGIT / "+" / "/" / "="
For example, a header whose value is defined as binary content could For example, a header whose value is defined as binary content could
look like: look like:
ExampleBinaryHeader: *cHJldGVuZCB0aGlzIGlzIGJpbmFyeSBjb250ZW50Lg* Example-BinaryHeader: *cHJldGVuZCB0aGlzIGlzIGJpbmFyeSBjb250ZW50Lg==*
Parsers MUST support binary content with at least 16384 octets after
decoding.
4.9.1. Parsing Binary Content from Text 4.9.1. Parsing Binary Content from Text
Given an ASCII string input_string, return binary content. Given an ASCII string input_string, return binary content.
input_string is modified to remove the parsed value. input_string is modified to remove the parsed value.
1. If the first character of input_string is not "*", fail parsing. 1. If the first character of input_string is not "*", fail parsing.
2. Discard the first character of input_string. 2. Discard the first character of input_string.
3. Let b64_content be the result of removing content of input_string 3. Let b64_content be the result of removing content of input_string
up to but not including the first instance of the character "*". up to but not including the first instance of the character "*".
If there is not a "*" character before the end of input_string, If there is not a "*" character before the end of input_string,
fail parsing. fail parsing.
4. Consume the "*" character at the beginning of input_string. 4. Consume the "*" character at the beginning of input_string.
5. If b64_content is has more than 21846 characters, fail parsing. 5. Let binary_content be the result of Base 64 Decoding [RFC4648]
6. Let binary_content be the result of Base 64 Decoding [RFC4648]
b64_content, synthesising padding if necessary (note the b64_content, synthesising padding if necessary (note the
requirements about recipient behaviour in Section 4.9). requirements about recipient behaviour in Section 4.9).
7. Return binary_content. 6. Return binary_content.
5. IANA Considerations 5. IANA Considerations
This draft has no actions for IANA. This draft has no actions for IANA.
6. Security Considerations 6. Security Considerations
TBD The size of most types defined by Structured Headers is not limited;
as a result, extremely large header fields could be an attack vector
(e.g., for resource consumption). Most HTTP implementations limit
the sizes of size of individual header fields as well as the overall
header block size to mitigate such attacks.
7. References It is possible for parties with the ability to inject new HTTP header
fields to change the meaning of a Structured Headers. In some
circumstances, this will cause parsing to fail, but it is not
possible to reliably fail in all such circumstances.
7. References
7.1. Normative References 7.1. Normative References
[RFC0020] Cerf, V., "ASCII format for network interchange", STD 80, [RFC0020] Cerf, V., "ASCII format for network interchange", STD 80,
RFC 20, DOI 10.17487/RFC0020, October 1969, RFC 20, DOI 10.17487/RFC0020, October 1969,
<https://www.rfc-editor.org/info/rfc20>. <https://www.rfc-editor.org/info/rfc20>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
skipping to change at page 18, line 7 skipping to change at page 18, line 35
Protocol (HTTP/1.1): Message Syntax and Routing", Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014, RFC 7230, DOI 10.17487/RFC7230, June 2014,
<https://www.rfc-editor.org/info/rfc7230>. <https://www.rfc-editor.org/info/rfc7230>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
7.2. Informative References 7.2. Informative References
[IEEE754] IEEE, "IEEE Standard for Floating-Point Arithmetic", 2008, [IEEE754] IEEE, "IEEE Standard for Floating-Point Arithmetic",
<http://grouper.ieee.org/groups/754/>. IEEE 754-2008, DOI 10.1109/IEEESTD.2008.4610935,
ISBN 978-0-7381-5752-8, August 2008,
<http://ieeexplore.ieee.org/document/4610935/>.
See also http://grouper.ieee.org/groups/754/ [6].
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005, RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>. <https://www.rfc-editor.org/info/rfc3986>.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer [RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content", RFC 7231, Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
DOI 10.17487/RFC7231, June 2014, DOI 10.17487/RFC7231, June 2014,
<https://www.rfc-editor.org/info/rfc7231>. <https://www.rfc-editor.org/info/rfc7231>.
skipping to change at page 18, line 33 skipping to change at page 19, line 18
<https://www.rfc-editor.org/info/rfc7540>. <https://www.rfc-editor.org/info/rfc7540>.
7.3. URIs 7.3. URIs
[1] https://lists.w3.org/Archives/Public/ietf-http-wg/ [1] https://lists.w3.org/Archives/Public/ietf-http-wg/
[2] https://httpwg.github.io/ [2] https://httpwg.github.io/
[3] https://github.com/httpwg/http-extensions/labels/header-structure [3] https://github.com/httpwg/http-extensions/labels/header-structure
[4] https://github.com/httpwg/structured-header-tests
[5] https://github.com/httpwg/wiki/wiki/Structured-Headers
Appendix A. Changes Appendix A. Changes
A.1. Since draft-ietf-httpbis-header-structure-03 A.1. Since draft-ietf-httpbis-header-structure-04
o Remove identifiers from item.
o Remove most limits on sizes.
o Refine number parsing.
A.2. Since draft-ietf-httpbis-header-structure-03
o Strengthen language around failure handling. o Strengthen language around failure handling.
A.2. Since draft-ietf-httpbis-header-structure-02 A.3. Since draft-ietf-httpbis-header-structure-02
o Split Numbers into Integers and Floats. o Split Numbers into Integers and Floats.
o Define number parsing. o Define number parsing.
o Tighten up binary parsing and give it an explicit end delimiter. o Tighten up binary parsing and give it an explicit end delimiter.
o Clarify that mappings are unordered. o Clarify that mappings are unordered.
o Allow zero-length strings. o Allow zero-length strings.
o Improve string parsing algorithm. o Improve string parsing algorithm.
o Improve limits in algorithms. o Improve limits in algorithms.
o Require parsers to combine header fields before processing. o Require parsers to combine header fields before processing.
o Throw an error on trailing garbage. o Throw an error on trailing garbage.
A.3. Since draft-ietf-httpbis-header-structure-01 A.4. Since draft-ietf-httpbis-header-structure-01
o Replaced with draft-nottingham-structured-headers. o Replaced with draft-nottingham-structured-headers.
A.4. Since draft-ietf-httpbis-header-structure-00 A.5. Since draft-ietf-httpbis-header-structure-00
o Added signed 64bit integer type. o Added signed 64bit integer type.
o Drop UTF8, and settle on BCP137 ::EmbeddedUnicodeChar for h1- o Drop UTF8, and settle on BCP137 ::EmbeddedUnicodeChar for h1-
unicode-string. unicode-string.
o Change h1_blob delimiter to ":" since "'" is valid t_char o Change h1_blob delimiter to ":" since "'" is valid t_char
Authors' Addresses Authors' Addresses
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