draft-ietf-httpbis-origin-frame-04.txt   draft-ietf-httpbis-origin-frame-05.txt 
HTTP Working Group M. Nottingham HTTP M. Nottingham
Internet-Draft Internet-Draft
Intended status: Standards Track E. Nygren Intended status: Standards Track E. Nygren
Expires: February 24, 2018 Akamai Expires: July 15, 2018 Akamai
August 23, 2017 January 11, 2018
The ORIGIN HTTP/2 Frame The ORIGIN HTTP/2 Frame
draft-ietf-httpbis-origin-frame-04 draft-ietf-httpbis-origin-frame-05
Abstract Abstract
This document specifies the ORIGIN frame for HTTP/2, to indicate what This document specifies the ORIGIN frame for HTTP/2, to indicate what
origins are available on a given connection. origins are available on a given connection.
Note to Readers Note to Readers
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/. https://lists.w3.org/Archives/Public/ietf-http-wg/ [1].
Working Group information can be found at http://httpwg.github.io/; Working Group information can be found at http://httpwg.github.io/
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/origin-frame. https://github.com/httpwg/http-extensions/labels/origin-frame [3].
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
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This Internet-Draft will expire on February 24, 2018. This Internet-Draft will expire on July 15, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 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.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Notational Conventions . . . . . . . . . . . . . . . . . 3 1.1. Notational Conventions . . . . . . . . . . . . . . . . . 3
2. The ORIGIN HTTP/2 Frame . . . . . . . . . . . . . . . . . . . 3 2. The ORIGIN HTTP/2 Frame . . . . . . . . . . . . . . . . . . . 3
2.1. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Syntax . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Processing ORIGIN Frames . . . . . . . . . . . . . . . . 3 2.2. Processing ORIGIN Frames . . . . . . . . . . . . . . . . 4
2.3. The Origin Set . . . . . . . . . . . . . . . . . . . . . 4 2.3. The Origin Set . . . . . . . . . . . . . . . . . . . . . 5
2.4. Authority, Push and Coalescing with ORIGIN . . . . . . . 5 2.4. Authority, Push and Coalescing with ORIGIN . . . . . . . 6
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
4. Security Considerations . . . . . . . . . . . . . . . . . . . 6 4. Security Considerations . . . . . . . . . . . . . . . . . . . 7
5. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 5. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.1. Normative References . . . . . . . . . . . . . . . . . . 7 5.1. Normative References . . . . . . . . . . . . . . . . . . 7
5.2. Informative References . . . . . . . . . . . . . . . . . 8 5.2. Informative References . . . . . . . . . . . . . . . . . 8
Appendix A. Non-Normative Processing Algorithm . . . . . . . . . 8 5.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Appendix A. Non-Normative Processing Algorithm . . . . . . . . . 9
Appendix B. Operational Considerations for Servers . . . . . . . 9 Appendix B. Operational Considerations for Servers . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction 1. Introduction
HTTP/2 [RFC7540] allows clients to coalesce different origins HTTP/2 [RFC7540] allows clients to coalesce different origins
[RFC6454] onto the same connection when certain conditions are met. [RFC6454] onto the same connection when certain conditions are met.
However, in certain cases, a connection is not usable for a coalesced However, in certain cases, a connection is not usable for a coalesced
origin, so the 421 (Misdirected Request) status code ([RFC7540], origin, so the 421 (Misdirected Request) status code ([RFC7540],
Section 9.1.2) was defined. Section 9.1.2) was defined.
skipping to change at page 3, line 8 skipping to change at page 3, line 10
Additionally, experience has shown that HTTP/2's requirement to Additionally, experience has shown that HTTP/2's requirement to
establish server authority using both DNS and the server's establish server authority using both DNS and the server's
certificate is onerous. This specification relaxes the requirement certificate is onerous. This specification relaxes the requirement
to check DNS when the ORIGIN frame is in use. Doing so has to check DNS when the ORIGIN frame is in use. Doing so has
additional benefits, such as removing the latency associated with additional benefits, such as removing the latency associated with
some DNS lookups. some DNS lookups.
1.1. Notational Conventions 1.1. Notational Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
document are to be interpreted as described in [RFC2119]. "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. The ORIGIN HTTP/2 Frame 2. The ORIGIN HTTP/2 Frame
The ORIGIN HTTP/2 frame ([RFC7540], Section 4) allows a server to This document defines a new HTTP/2 frame type ([RFC7540], Section 4)
indicate what origin(s) [RFC6454] the server would like the client to called ORIGIN, that allows a server to indicate what origin(s)
consider as members of the Origin Set (Section 2.3) for the [RFC6454] the server would like the client to consider as members of
connection it occurs within. the Origin Set (Section 2.3) for the connection it occurs within.
2.1. Syntax 2.1. Syntax
The ORIGIN frame type is 0xc (decimal 12), and contains zero to many The ORIGIN frame type is 0xc (decimal 12), and contains zero or more
Origin-Entry. instances of the Origin-Entry field.
+-------------------------------+-------------------------------+ +-------------------------------+-------------------------------+
| Origin-Entry (*) ... | Origin-Entry (*) ...
+-------------------------------+-------------------------------+ +-------------------------------+-------------------------------+
An Origin-Entry is a length-delimited string: An Origin-Entry is a length-delimited string:
+-------------------------------+-------------------------------+ +-------------------------------+-------------------------------+
| Origin-Len (16) | ASCII-Origin? ... | Origin-Len (16) | ASCII-Origin? ...
+-------------------------------+-------------------------------+ +-------------------------------+-------------------------------+
Specifically: Specifically:
Origin-Len: An unsigned, 16-bit integer indicating the length, in Origin-Len: An unsigned, 16-bit integer indicating the length, in
octets, of the ASCII-Origin field. octets, of the ASCII-Origin field.
Origin: An OPTIONAL sequence of characters containing the ASCII Origin: An OPTIONAL sequence of characters containing the ASCII
serialization of an origin ([RFC6454], Section 6.2) that the serialization of an origin ([RFC6454], Section 6.2) that the
sender believes this connection is or could be authoritative for. sender asserts this connection is or could be authoritative for.
The ORIGIN frame does not define any flags. However, future updates The ORIGIN frame does not define any flags. However, future updates
to this specification MAY define flags. See Section 2.2. to this specification MAY define flags. See Section 2.2.
2.2. Processing ORIGIN Frames 2.2. Processing ORIGIN Frames
The ORIGIN frame is a non-critical extension to HTTP/2. Endpoints The ORIGIN frame is a non-critical extension to HTTP/2. Endpoints
that do not support this frame can safely ignore it upon receipt. that do not support this frame can safely ignore it upon receipt.
When received by an implementing client, it is used to initialise and When received by an implementing client, it is used to initialise and
manipulate the Origin Set (see Section 2.3), thereby changing how the manipulate the Origin Set (see Section 2.3), thereby changing how the
client establishes authority for origin servers (see Section 2.4). client establishes authority for origin servers (see Section 2.4).
The origin frame MUST be sent on stream 0; an ORIGIN frame on any The ORIGIN frame MUST be sent on stream 0; an ORIGIN frame on any
other stream is invalid and MUST be ignored. other stream is invalid and MUST be ignored.
Likewise, the ORIGIN frame is only valid on connections with the "h2" Likewise, the ORIGIN frame is only valid on connections with the "h2"
protocol identifier, or when specifically nominated by the protocol's protocol identifier, or when specifically nominated by the protocol's
definition; it MUST be ignored when received on a connection with the definition; it MUST be ignored when received on a connection with the
"h2c" protocol identifier. "h2c" protocol identifier.
This specification does not define any flags for the ORIGIN frame, This specification does not define any flags for the ORIGIN frame,
but future updates might use them to change its semantics. The first but future updates to this specification (through IETF consensus)
four flags (0x1, 0x2, 0x4 and 0x8) are reserved for backwards- might use them to change its semantics. The first four flags (0x1,
incompatible changes, and therefore when any of them are set, the 0x2, 0x4 and 0x8) are reserved for backwards-incompatible changes,
ORIGIN frame containing them MUST be ignored by clients conforming to and therefore when any of them are set, the ORIGIN frame containing
this specification, unless the flag's semantics are understood. The them MUST be ignored by clients conforming to this specification,
remaining flags are reserved for backwards-compatible changes, and do unless the flag's semantics are understood. The remaining flags are
not affect processing by clients conformant to this specification. reserved for backwards-compatible changes, and do not affect
processing by clients conformant to this specification.
The ORIGIN frame describes a property of the connection, and The ORIGIN frame describes a property of the connection, and
therefore is processed hop-by-hop. An intermediary MUST NOT forward therefore is processed hop-by-hop. An intermediary MUST NOT forward
ORIGIN frames. Clients configured to use a proxy MUST ignore any ORIGIN frames. Clients configured to use a proxy MUST ignore any
ORIGIN frames received from it. ORIGIN frames received from it.
Each ASCII-Origin field in the frame's payload MUST be parsed as an Each ASCII-Origin field in the frame's payload MUST be parsed as an
ASCII serialisation of an origin ([RFC6454], Section 6.2). If ASCII serialisation of an origin ([RFC6454], Section 6.2). If
parsing fails, the field MUST be ignored. parsing fails, the field MUST be ignored.
Note that the ORIGIN frame does not support wildcard names (e.g.,
"*.example.com") in Origin-Entry. As a result, sending ORIGIN when a
wildcard certificate is in use effectively disables any origins that
are not explicitly listed in the ORIGIN frame(s) (when the client
understands ORIGIN).
See Appendix A for an illustrative algorithm for processing ORIGIN See Appendix A for an illustrative algorithm for processing ORIGIN
frames. frames.
2.3. The Origin Set 2.3. The Origin Set
The set of origins (as per [RFC6454]) that a given connection might The set of origins (as per [RFC6454]) that a given connection might
be used for is known in this specification as the Origin Set. be used for is known in this specification as the Origin Set.
By default, the Origin Set for a connection is uninitialised. When By default, the Origin Set for a connection is uninitialised. When
an ORIGIN frame is first received and successfully processed by a an ORIGIN frame is first received and successfully processed by a
client, the connection's Origin Set is defined to contain an initial client, the connection's Origin Set is defined to contain an initial
origin. The initial origin is composed from: origin. The initial origin is composed from:
o Scheme: "https" o Scheme: "https"
o Host: the value sent in Server Name Indication (SNI, [RFC6066] o Host: the value sent in Server Name Indication (SNI, [RFC6066],
Section 3), converted to lower case Section 3), converted to lower case; if SNI is not present, the
remote address of the connection (i.e., the server's IP address)
o Port: the remote port of the connection (i.e., the server's port) o Port: the remote port of the connection (i.e., the server's port)
The contents of that ORIGIN frame (and subsequent ones) allows the The contents of that ORIGIN frame (and subsequent ones) allows the
server to incrementally add new origins to the Origin Set, as server to incrementally add new origins to the Origin Set, as
described in Section 2.2. described in Section 2.2.
The Origin Set is also affected by the 421 (Misdirected Request) The Origin Set is also affected by the 421 (Misdirected Request)
response status code, defined in [RFC7540] Section 9.1.2. Upon response status code, defined in [RFC7540], Section 9.1.2. Upon
receipt of a response with this status code, implementing clients receipt of a response with this status code, implementing clients
MUST create the ASCII serialisation of the corresponding request's MUST create the ASCII serialisation of the corresponding request's
origin (as per [RFC6454], Section 6.2) and remove it from the origin (as per [RFC6454], Section 6.2) and remove it from the
connection's Origin Set, if present. connection's Origin Set, if present.
Note: When sending an ORIGIN frame to a connection that is Note: When sending an ORIGIN frame to a connection that is
initialised as an Alternative Service [RFC7838], the initial initialised as an Alternative Service [RFC7838], the initial
origin set Section 2.3 will contain an origin with the appropriate origin set (Section 2.3) will contain an origin with the
scheme and hostname (since Alternative Services specifies that the appropriate scheme and hostname (since Alternative Services
origin's hostname be sent in SNI). However, it is possible that specifies that the origin's hostname be sent in SNI). However, it
the port will be different than that of the intended origin, since is possible that the port will be different than that of the
the initial origin set is calculated using the actual port in use, intended origin, since the initial origin set is calculated using
which can be different for the alternative service. In this case, the actual port in use, which can be different for the alternative
the intended origin needs to be sent in the ORIGIN frame service. In this case, the intended origin needs to be sent in
explicitly. the ORIGIN frame explicitly.
For example, a client making requests for "https://example.com" is For example, a client making requests for "https://example.com" is
directed to an alternative service at ("h2", "x.example.net", directed to an alternative service at ("h2", "x.example.net",
"8443"). If this alternative service sends an ORIGIN frame, the "8443"). If this alternative service sends an ORIGIN frame, the
initial origin will be "https://example.com:8443". The client initial origin will be "https://example.com:8443". The client
will not be able to use the alternative service to make requests will not be able to use the alternative service to make requests
for "https://example.com" unless that origin is explicitly for "https://example.com" unless that origin is explicitly
included in the ORIGIN frame. included in the ORIGIN frame.
2.4. Authority, Push and Coalescing with ORIGIN 2.4. Authority, Push and Coalescing with ORIGIN
[RFC7540], Section 10.1 uses both DNS and the presented TLS Section 10.1 of [RFC7540] uses both DNS and the presented TLS
certificate to establish the origin server(s) that a connection is certificate to establish the origin server(s) that a connection is
authoritative for, just as HTTP/1.1 does in [RFC7230]. authoritative for, just as HTTP/1.1 does in [RFC7230].
Furthermore, [RFC7540] Section 9.1.1 explicitly allows a connection Furthermore, Section 9.1.1 of [RFC7540] explicitly allows a
to be used for more than one origin server, if it is authoritative. connection to be used for more than one origin server, if it is
This affects what requests can be sent on the connection, both in authoritative. This affects what responses can be considered
HEADERS frame by the client and as PUSH_PROMISE frames from the authoritative, both for direct responses to requests and for server
server ([RFC7540], Section 8.2.2). push (see [RFC7540], Section 8.2.2). Indirectly, it also affects
what requests will be sent on a connection, since clients will
generally only send requests on connections that they believe to be
authoritative for the origin in question.
Once an Origin Set has been initialised for a connection, clients Once an Origin Set has been initialised for a connection, clients
that implement this specification use it to help determine what the that implement this specification use it to help determine what the
connection is authoritative for. Specifically, such clients MUST NOT connection is authoritative for. Specifically, such clients MUST NOT
consider a connection to be authoritative for an origin not present consider a connection to be authoritative for an origin not present
in the Origin Set, and SHOULD use the connection for all requests to in the Origin Set, and SHOULD use the connection for all requests to
origins in the Origin Set for which the connection is authoritative, origins in the Origin Set for which the connection is authoritative,
unless there are operational reasons for opening a new connection. unless there are operational reasons for opening a new connection.
Note that for a connection to be considered authoritative for a given Note that for a connection to be considered authoritative for a given
origin, the client is still required to obtain a certificate that origin, the server is still required to authenticate with certificate
passes suitable checks; see [RFC7540] Section 9.1.1 for more that passes suitable checks; see Section 9.1.1 of [RFC7540] for more
information. This includes verifying that the host matches a information. This includes verifying that the host matches a
"dNSName" value from the certificate "subjectAltName" field (using "dNSName" value from the certificate "subjectAltName" field (using
the wildcard rules defined in [RFC2818]; see also [RFC5280] the rules defined in [RFC2818]; see also [RFC5280], Section 4.2.1.6).
Section 4.2.1.6).
Additionally, clients MAY avoid consulting DNS to establish the Additionally, clients MAY avoid consulting DNS to establish the
connection's authority for new requests; however, those that do so connection's authority for new requests to origins in the Origin Set;
face new risks, as explained in Section 4 however, those that do so face new risks, as explained in Section 4.
Because ORIGIN can change the set of origins a connection is used for Because ORIGIN can change the set of origins a connection is used for
over time, it is possible that a client might have more than one over time, it is possible that a client might have more than one
viable connection to an origin open at any time. When this occurs, viable connection to an origin open at any time. When this occurs,
clients SHOULD not emit new requests on any connection whose Origin clients SHOULD NOT emit new requests on any connection whose Origin
Set is a proper subset of another connection's Origin Set, and SHOULD Set is a proper subset of another connection's Origin Set, and SHOULD
close it once all outstanding requests are satisfied. close it once all outstanding requests are satisfied.
The Origin Set is unaffected by any alternative services [RFC7838] The Origin Set is unaffected by any alternative services [RFC7838]
advertisements made by the server. Advertising an alternative advertisements made by the server. Advertising an alternative
service does not affect whether a server is authoritative. service does not affect whether a server is authoritative.
3. IANA Considerations 3. IANA Considerations
This specification adds an entry to the "HTTP/2 Frame Type" registry. This specification adds an entry to the "HTTP/2 Frame Type" registry.
skipping to change at page 7, line 6 skipping to change at page 7, line 29
mitigations. mitigations.
Relaxing the requirement to consult DNS when determining authority Relaxing the requirement to consult DNS when determining authority
for an origin means that an attacker who possesses a valid for an origin means that an attacker who possesses a valid
certificate no longer needs to be on-path to redirect traffic to certificate no longer needs to be on-path to redirect traffic to
them; instead of modifying DNS, they need only convince the user to them; instead of modifying DNS, they need only convince the user to
visit another Web site in order to coalesce connections to the target visit another Web site in order to coalesce connections to the target
onto their existing connection. onto their existing connection.
As a result, clients opting not to consult DNS ought to employ some As a result, clients opting not to consult DNS ought to employ some
alternative means to increase confidence that the certificate is alternative means to establish a high degree of confidence that the
legitimate. Examples of mechanisms that can give additional certificate is legitimate. For example, clients might skip
confidence in a certificate include checking for a Signed Certificate consulting DNS only if they receive proof of inclusion in a
Timestamp [RFC6929] and performing certificate revocation checks. Certificate Transparency log [RFC6962] or they have a recent OCSP
response [RFC6960] (possibly using the "status_request" TLS extension
Clients opting not to consult DNS ought to do so only if they have a [RFC6066]) showing that the certificate was not revoked.
high degree of confidence that the certificate is legitimate. For
instance, clients might skip consulting DNS only if they receive
proof of inclusion in a Certificate Transparency log [RFC6929] or
they have a recent OCSP response [RFC6960] (possibly using the
"status_request" TLS extension [RFC6066]) showing that the
certificate was not revoked.
The Origin Set's size is unbounded by this specification, and thus The Origin Set's size is unbounded by this specification, and thus
could be used by attackers to exhaust client resources. To mitigate could be used by attackers to exhaust client resources. To mitigate
this risk, clients can monitor their state commitment and close the this risk, clients can monitor their state commitment and close the
connection if it is too high. connection if it is too high.
5. References 5. References
5.1. Normative References 5.1. Normative References
[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, <https://www.rfc- DOI 10.17487/RFC2119, March 1997,
editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818,
DOI 10.17487/RFC2818, May 2000, <https://www.rfc- DOI 10.17487/RFC2818, May 2000,
editor.org/info/rfc2818>. <https://www.rfc-editor.org/info/rfc2818>.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008, (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
<https://www.rfc-editor.org/info/rfc5280>. <https://www.rfc-editor.org/info/rfc5280>.
[RFC6066] Eastlake 3rd, D., "Transport Layer Security (TLS) [RFC6066] Eastlake 3rd, D., "Transport Layer Security (TLS)
Extensions: Extension Definitions", RFC 6066, Extensions: Extension Definitions", RFC 6066,
DOI 10.17487/RFC6066, January 2011, <https://www.rfc- DOI 10.17487/RFC6066, January 2011,
editor.org/info/rfc6066>. <https://www.rfc-editor.org/info/rfc6066>.
[RFC6454] Barth, A., "The Web Origin Concept", RFC 6454, [RFC6454] Barth, A., "The Web Origin Concept", RFC 6454,
DOI 10.17487/RFC6454, December 2011, <https://www.rfc- DOI 10.17487/RFC6454, December 2011,
editor.org/info/rfc6454>. <https://www.rfc-editor.org/info/rfc6454>.
[RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext [RFC7540] Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
Transfer Protocol Version 2 (HTTP/2)", RFC 7540, Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015, <https://www.rfc- DOI 10.17487/RFC7540, May 2015,
editor.org/info/rfc7540>. <https://www.rfc-editor.org/info/rfc7540>.
5.2. Informative References
[RFC5988] Nottingham, M., "Web Linking", RFC 5988, [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
DOI 10.17487/RFC5988, October 2010, <https://www.rfc- 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
editor.org/info/rfc5988>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC6929] DeKok, A. and A. Lior, "Remote Authentication Dial In User 5.2. Informative References
Service (RADIUS) Protocol Extensions", RFC 6929,
DOI 10.17487/RFC6929, April 2013, <https://www.rfc-
editor.org/info/rfc6929>.
[RFC6960] Santesson, S., Myers, M., Ankney, R., Malpani, A., [RFC6960] Santesson, S., Myers, M., Ankney, R., Malpani, A.,
Galperin, S., and C. Adams, "X.509 Internet Public Key Galperin, S., and C. Adams, "X.509 Internet Public Key
Infrastructure Online Certificate Status Protocol - OCSP", Infrastructure Online Certificate Status Protocol - OCSP",
RFC 6960, DOI 10.17487/RFC6960, June 2013, RFC 6960, DOI 10.17487/RFC6960, June 2013,
<https://www.rfc-editor.org/info/rfc6960>. <https://www.rfc-editor.org/info/rfc6960>.
[RFC6962] Laurie, B., Langley, A., and E. Kasper, "Certificate
Transparency", RFC 6962, DOI 10.17487/RFC6962, June 2013,
<https://www.rfc-editor.org/info/rfc6962>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
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>.
[RFC7838] Nottingham, M., McManus, P., and J. Reschke, "HTTP [RFC7838] Nottingham, M., McManus, P., and J. Reschke, "HTTP
Alternative Services", RFC 7838, DOI 10.17487/RFC7838, Alternative Services", RFC 7838, DOI 10.17487/RFC7838,
April 2016, <https://www.rfc-editor.org/info/rfc7838>. April 2016, <https://www.rfc-editor.org/info/rfc7838>.
[RFC8288] Nottingham, M., "Web Linking", RFC 8288,
DOI 10.17487/RFC8288, October 2017,
<https://www.rfc-editor.org/info/rfc8288>.
5.3. URIs
[1] https://lists.w3.org/Archives/Public/ietf-http-wg/
[2] http://httpwg.github.io/
[3] https://github.com/httpwg/http-extensions/labels/origin-frame
Appendix A. Non-Normative Processing Algorithm Appendix A. Non-Normative Processing Algorithm
The following algorithm illustrates how a client could handle The following algorithm illustrates how a client could handle
received ORIGIN frames: received ORIGIN frames:
1. If the client is configured to use a proxy for the connection, 1. If the client is configured to use a proxy for the connection,
ignore the frame and stop processing. ignore the frame and stop processing.
2. If the connection is not identified with the "h2" protocol 2. If the connection is not identified with the "h2" protocol
identifier or another protocol that has explicitly opted into identifier or another protocol that has explicitly opted into
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obligated to use it, or to advertise all origins which they might be obligated to use it, or to advertise all origins which they might be
able to answer a request for. able to answer a request for.
For example, it can be used to inform the client that the connection For example, it can be used to inform the client that the connection
is to only be used for the SNI-based origin, by sending an empty is to only be used for the SNI-based origin, by sending an empty
ORIGIN frame. Or, a larger number of origins can be indicated by ORIGIN frame. Or, a larger number of origins can be indicated by
including a payload. including a payload.
Generally, this information is most useful to send before sending any Generally, this information is most useful to send before sending any
part of a response that might initiate a new connection; for example, part of a response that might initiate a new connection; for example,
"Link" headers [RFC5988] in a response HEADERS, or links in the "Link" header fields [RFC8288] in a response HEADERS, or links in the
response body. response body.
Therefore, the ORIGIN frame ought be sent as soon as possible on a Therefore, the ORIGIN frame ought be sent as soon as possible on a
connection, ideally before any HEADERS or PUSH_PROMISE frames. connection, ideally before any HEADERS or PUSH_PROMISE frames.
However, if it's desirable to associate a large number of origins However, if it's desirable to associate a large number of origins
with a connection, doing so might introduce end-user perceived with a connection, doing so might introduce end-user perceived
latency, due to their size. As a result, it might be necessary to latency, due to their size. As a result, it might be necessary to
select a "core" set of origins to send initially, expanding the set select a "core" set of origins to send initially, expanding the set
of origins the connection is used for with subsequent ORIGIN frames of origins the connection is used for with subsequent ORIGIN frames
later (e.g., when the connection is idle). later (e.g., when the connection is idle).
That said, senders are encouraged to include as many origins as That said, senders are encouraged to include as many origins as
practical within a single ORIGIN frame; clients need to make practical within a single ORIGIN frame; clients need to make
decisions about creating connections on the fly, and if the origin decisions about creating connections on the fly, and if the origin
set is split across many frames, their behaviour might be suboptimal. set is split across many frames, their behaviour might be suboptimal.
Senders take note that, as per [RFC6454] Section 4, the values in an Senders take note that, as per Section 4, Step 5 of [RFC6454], the
ORIGIN header need to be case-normalised before serialisation. values in an ORIGIN header need to be case-normalised before
serialisation.
Finally, servers that host alternative services [RFC7838] will need Finally, servers that host alternative services [RFC7838] will need
to explicitly advertise their origins when sending ORIGIN, because to explicitly advertise their origins when sending ORIGIN, because
the default contents of the Origin Set (as per Section 2.3) do not the default contents of the Origin Set (as per Section 2.3) do not
contain any Alternative Services' origins, even if they have been contain any Alternative Services' origins, even if they have been
used previously on the connection. used previously on the connection.
Authors' Addresses Authors' Addresses
Mark Nottingham Mark Nottingham
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