RFC 9412 | ORIGIN in HTTP/3 | June 2023 |
Bishop | Standards Track | [Page] |
The ORIGIN frame for HTTP/2 is equally applicable to HTTP/3, but itneeds to be separately registered. This document describes the ORIGINframe for HTTP/3.¶
This is an Internet Standards Track document.¶
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). Further information on Internet Standards is available in 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 athttps://www.rfc-editor.org/info/rfc9412.¶
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Existing RFCs define extensions to HTTP/2[HTTP/2] that remain useful inHTTP/3.Appendix A.2 of [HTTP/3] describes the required updates for HTTP/2frames to be used with HTTP/3.¶
[ORIGIN] defines the HTTP/2 ORIGIN frame, which indicates whatorigins are available on a given connection. It defines a single HTTP/2 frametype.¶
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.¶
The frame diagram in this document uses the format defined inSection 1.3 of [QUIC-TRANSPORT] to illustrate the order and size of fields.¶
The ORIGIN HTTP/3 frame allows a server to indicate what origin or origins[RFC6454] the server would like the client to consider as one or more members of theOrigin Set (Section 2.3 of [ORIGIN]) for the connection within which itoccurs.¶
The semantics of the frame payload are identical to those of the HTTP/2 framedefined in[ORIGIN]. Where HTTP/2 reserves stream 0 for frames related to thestate of the connection, HTTP/3 defines a pair of unidirectional streams called"control streams" for this purpose.¶
Where[ORIGIN] indicates that the ORIGINframe is sent on stream 0, this should be interpreted to mean the HTTP/3control stream: that is, the ORIGIN frame is sent from servers to clients on theserver's control stream.¶
HTTP/3 does not define a Flags field in the generic frame layout. As no flagshave been defined for the ORIGIN frame, this specification does not define amechanism for communicating such flags in HTTP/3.¶
The ORIGIN frame has a layout that is nearly identical to the layout used in HTTP/2; the information is restatedhere for clarity. The ORIGIN frame type is 0x0c (decimal 12), as in HTTP/2. Thepayload contains zero or more instances of the Origin-Entry field.¶
HTTP/3 Origin-Entry { Origin-Len (16), ASCII-Origin (..),}HTTP/3 ORIGIN Frame { Type (i) = 0x0c, Length (i), Origin-Entry (..) ...,}
An Origin-Entry is a length-delimited string. Specifically, it contains twofields:¶
An unsigned, 16-bit integer indicating the length, in octets, ofthe ASCII-Origin field.¶
AnOPTIONAL sequence of characters containing the ASCII serialization of anorigin ([RFC6454],Section 6.2) that the sender asserts this connection isor could be authoritative for.¶
This document introduces no new security considerations beyond those discussedin[ORIGIN] and[HTTP/3].¶
This document registers a frame type in the "HTTP/3 Frame Types"registry defined by[HTTP/3], located at<https://www.iana.org/assignments/http3-parameters/>.¶