draft-ietf-quic-http-00.txt   draft-ietf-quic-http-01.txt 
QUIC M. Bishop, Ed. QUIC M. Bishop, Ed.
Internet-Draft Microsoft Internet-Draft Microsoft
Intended status: Standards Track November 28, 2016 Intended status: Standards Track January 14, 2017
Expires: June 1, 2017 Expires: July 18, 2017
Hypertext Transfer Protocol (HTTP) over QUIC Hypertext Transfer Protocol (HTTP) over QUIC
draft-ietf-quic-http-00 draft-ietf-quic-http-01
Abstract Abstract
The QUIC transport protocol has several features that are desirable The QUIC transport protocol has several features that are desirable
in a transport for HTTP/2, such as stream multiplexing, per-stream in a transport for HTTP, such as stream multiplexing, per-stream flow
flow control, and low-latency connection establishment. This control, and low-latency connection establishment. This document
document describes a mapping of HTTP/2 semantics over QUIC. describes a mapping of HTTP semantics over QUIC. Specifically, this
Specifically, this document identifies HTTP/2 features that are document identifies HTTP/2 features that are subsumed by QUIC, and
subsumed by QUIC, and describes how the other features can be describes how the other features can be implemented atop QUIC.
implemented atop QUIC.
Note to Readers
Discussion of this draft takes place on the QUIC working group
mailing list (quic@ietf.org), which is archived at
https://mailarchive.ietf.org/arch/search/?email_list=quic .
Working Group information can be found at https://github.com/quicwg ;
source code and issues list for this draft can be found at
https://github.com/quicwg/base-drafts/labels/http .
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 http://datatracker.ietf.org/drafts/current/. Drafts is at http://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 June 1, 2017. This Internet-Draft will expire on July 18, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Notational Conventions . . . . . . . . . . . . . . . . . 2 1.1. Notational Conventions . . . . . . . . . . . . . . . . . 3
2. QUIC advertisement . . . . . . . . . . . . . . . . . . . . . 3 2. QUIC Advertisement . . . . . . . . . . . . . . . . . . . . . 3
3. Connection establishment . . . . . . . . . . . . . . . . . . 3 2.1. QUIC Version Hints . . . . . . . . . . . . . . . . . . . 4
4. Sending a request on an HTTP/2-over-QUIC connection . . . . . 4 3. Connection Establishment . . . . . . . . . . . . . . . . . . 4
4.1. Terminating a stream . . . . . . . . . . . . . . . . . . 4 3.1. Draft Version Identification . . . . . . . . . . . . . . 5
5. Writing data to QUIC streams . . . . . . . . . . . . . . . . 5 4. Stream Mapping and Usage . . . . . . . . . . . . . . . . . . 5
6. Stream Mapping . . . . . . . . . . . . . . . . . . . . . . . 5 4.1. Stream 3: Connection Control Stream . . . . . . . . . . . 6
6.1. Reserved Streams . . . . . . . . . . . . . . . . . . . . 5 4.2. HTTP Message Exchanges . . . . . . . . . . . . . . . . . 6
6.1.1. Stream 3: headers . . . . . . . . . . . . . . . . . . 6 4.2.1. Header Compression . . . . . . . . . . . . . . . . . 7
6.1.2. Stream states . . . . . . . . . . . . . . . . . . . . 6 4.2.2. The CONNECT Method . . . . . . . . . . . . . . . . . 8
7. Stream Priorities . . . . . . . . . . . . . . . . . . . . . . 7 4.3. Stream Priorities . . . . . . . . . . . . . . . . . . . . 9
8. Flow Control . . . . . . . . . . . . . . . . . . . . . . . . 8 4.4. Flow Control . . . . . . . . . . . . . . . . . . . . . . 9
9. Server Push . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.5. Server Push . . . . . . . . . . . . . . . . . . . . . . . 9
10. Error Codes . . . . . . . . . . . . . . . . . . . . . . . . . 8 5. HTTP Framing Layer . . . . . . . . . . . . . . . . . . . . . 10
11. Other HTTP/2 frames . . . . . . . . . . . . . . . . . . . . . 9 5.1. Frame Layout . . . . . . . . . . . . . . . . . . . . . . 10
11.1. GOAWAY frame . . . . . . . . . . . . . . . . . . . . . . 9 5.2. Frame Definitions . . . . . . . . . . . . . . . . . . . . 11
11.2. PING frame . . . . . . . . . . . . . . . . . . . . . . . 10 5.2.1. DATA . . . . . . . . . . . . . . . . . . . . . . . . 11
11.3. PADDING frame . . . . . . . . . . . . . . . . . . . . . 10 5.2.2. HEADERS . . . . . . . . . . . . . . . . . . . . . . . 11
12. Security Considerations . . . . . . . . . . . . . . . . . . . 10 5.2.3. PRIORITY . . . . . . . . . . . . . . . . . . . . . . 12
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 5.2.4. RST_STREAM . . . . . . . . . . . . . . . . . . . . . 13
14. Normative References . . . . . . . . . . . . . . . . . . . . 10 5.2.5. SETTINGS . . . . . . . . . . . . . . . . . . . . . . 13
Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . 11 5.2.6. PUSH_PROMISE . . . . . . . . . . . . . . . . . . . . 16
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 11 5.2.7. PING . . . . . . . . . . . . . . . . . . . . . . . . 17
5.2.8. GOAWAY frame . . . . . . . . . . . . . . . . . . . . 17
5.2.9. WINDOW_UPDATE frame . . . . . . . . . . . . . . . . . 17
5.2.10. CONTINUATION frame . . . . . . . . . . . . . . . . . 17
5.2.11. SETTINGS_ACK Frame . . . . . . . . . . . . . . . . . 18
6. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 19
6.1. HTTP-Defined QUIC Error Codes . . . . . . . . . . . . . . 19
6.2. Mapping HTTP/2 Error Codes . . . . . . . . . . . . . . . 20
7. Security Considerations . . . . . . . . . . . . . . . . . . . 21
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
8.1. Registration of HTTP/QUIC Identification String . . . . . 21
8.2. Registration of Version Hint Alt-Svc Parameter . . . . . 21
8.3. Existing Frame Types . . . . . . . . . . . . . . . . . . 22
8.4. New Frame Types . . . . . . . . . . . . . . . . . . . . . 23
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 23
9.1. Normative References . . . . . . . . . . . . . . . . . . 23
9.2. Informative References . . . . . . . . . . . . . . . . . 24
Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . 24
Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 24
B.1. Since draft-ietf-quic-http-00: . . . . . . . . . . . . . 24
B.2. Since draft-shade-quic-http2-mapping-00: . . . . . . . . 25
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 25
1. Introduction 1. Introduction
The QUIC transport protocol has several features that are desirable The QUIC transport protocol has several features that are desirable
in a transport for HTTP/2, such as stream multiplexing, per-stream in a transport for HTTP, such as stream multiplexing, per-stream flow
flow control, and low-latency connection establishment. This control, and low-latency connection establishment. This document
document describes a mapping of HTTP/2 semantics over QUIC. describes a mapping of HTTP semantics over QUIC, drawing heavily on
Specifically, this document identifies HTTP/2 features that are the existing TCP mapping, HTTP/2. Specifically, this document
subsumed by QUIC, and describes how the other features can be identifies HTTP/2 features that are subsumed by QUIC, and describes
implemented atop QUIC. how the other features can be implemented atop QUIC.
QUIC is described in [QUIC-TRANSPORT]. For a full description of QUIC is described in [QUIC-TRANSPORT]. For a full description of
HTTP/2, see [RFC7540]. HTTP/2, see [RFC7540].
1.1. Notational Conventions 1.1. Notational Conventions
The words "MUST", "MUST NOT", "SHOULD", and "MAY" are used in this The words "MUST", "MUST NOT", "SHOULD", and "MAY" are used in this
document. It's not shouting; when they are capitalized, they have document. It's not shouting; when they are capitalized, they have
the special meaning defined in [RFC2119]. the special meaning defined in [RFC2119].
2. QUIC advertisement 2. QUIC Advertisement
A server advertises that it can speak HTTP/2-over-QUIC via the Alt- A server advertises that it can speak HTTP/QUIC via the Alt-Svc
Svc HTTP response header. It does so by including the header in any ([RFC7838]) HTTP response header (or the semantically equivalent Alt-
response sent over a non-QUIC (e.g. HTTP/2 over TLS) connection: Svc HTTP/2 Extension Frame Type), using the ALPN token defined in
Section 3.
Alt-Svc: quic=":443" Thus, a server could indicate in an HTTP/1.1 or HTTP/2 response that
HTTP/QUIC was available on UDP port 443 by including the following
header in any response:
In addition, the list of QUIC versions supported by the server can be Alt-Svc: hq=":443"
specified by the v= parameter. For example, if a server supported
both version 33 and 34 it would specify the following header:
Alt-Svc: quic=":443"; v="34,33" 2.1. QUIC Version Hints
On receipt of this header, a client may attempt to establish a QUIC This document defines the "v" parameter for Alt-Svc, which is used to
connection on port 443 and, if successful, send HTTP/2 requests using provide version-negotiation hints to HTTP/QUIC clients. Syntax:
the mapping described in this document.
Connectivity problems (e.g. firewall blocking UDP) may result in QUIC v = version
connection establishment failure, in which case the client should version = DQUOTE ( "c" version-string / "x" version-number ) DQUOTE
gracefully fallback to HTTP/2-over-TLS/TCP. version-string = token; percent-encoded QUIC version
version-number = 1*8 HEXDIG; hex-encoded QUIC version
3. Connection establishment When multiple versions are supported, the "v" parameter MAY be
repeated multiple times in a single Alt-Svc entry. For example, if a
server supported both version "Q034" and version 0x00000001, it would
specify the following header:
HTTP/2-over-QUIC connections are established as described in Alt-Svc: hq=":443";v="x1";v="cQ034"
[QUIC-TRANSPORT]. The QUIC crypto handshake MUST use TLS [QUIC-TLS].
While connection-level options pertaining to the core QUIC protocol Where multiple versions are listed, the order of the values reflects
are set in the initial crypto handshake [QUIC-TLS]. HTTP/2-specific the server's preference (with the first value being the most
settings are conveyed in the HTTP/2 SETTINGS frame. After the QUIC preferred version).
connection is established, an HTTP/2 SETTINGS frame may be sent as
the initial frame of the QUIC headers stream (StreamID 3, See
Section 6). As in HTTP/2, additional SETTINGS frames may be sent
mid-connection by either endpoint.
TODO: Decide whether to acknowledge receipt of SETTINGS through QUIC versions are four-octet sequences with no additional constraints
empty SETTINGS frames with ACK bit set, as in HTTP/2, or rely on on format. Versions containing octets not allowed in tokens
transport- level acknowledgment. ([RFC7230], Section 3.2.6) MUST be encoded using the hexidecimal
representation. Versions containing only octets allowed in tokens
MAY be encoded using either representation.
Some transport-level options that HTTP/2-over-TCP specifies via the On receipt of an Alt-Svc header indicating QUIC support, a client MAY
SETTINGS frame are superseded by QUIC transport parameters in HTTP/2- attempt to establish a QUIC connection on the indicated port and, if
over-QUIC. Below is a listing of how each HTTP/2 SETTINGS parameter successful, send HTTP requests using the mapping described in this
is mapped: document. Servers SHOULD list only versions which they support, but
MAY omit supported versions for any reason.
SETTINGS_HEADER_TABLE_SIZE: Sent in HTTP/2 SETTINGS frame. Connectivity problems (e.g. firewall blocking UDP) may result in QUIC
connection establishment failure, in which case the client should
gracefully fall back to HTTP/2.
SETTINGS_ENABLE_PUSH: Sent in HTTP/2 SETTINGS frame (TBD, currently 3. Connection Establishment
set using QUIC "SPSH" connection option)
SETTINGS_MAX_CONCURRENT_STREAMS QUIC requires the maximum number of HTTP/QUIC connections are established as described in
incoming streams per connection to be specified in the initial [QUIC-TRANSPORT]. During connection establishment, HTTP/QUIC support
crypto handshake, using the "MSPC" tag. Specifying is indicated by selecting the ALPN token "hq" in the crypto
SETTINGS_MAX_CONCURRENT_STREAMS in the HTTP/2 SETTINGS frame is an handshake.
error.
SETTINGS_INITIAL_WINDOW_SIZE: QUIC requires both stream and While connection-level options pertaining to the core QUIC protocol
connection flow control window sizes to be specified in the are set in the initial crypto handshake, HTTP-specific settings are
initial crypto handshake, using the "SFCW" and "CFCW" tags, conveyed in the SETTINGS frame. After the QUIC connection is
respectively. Specifying SETTINGS_INITIAL_WINDOW_SIZE in the established, a SETTINGS frame (Section 5.2.5) MUST be sent as the
HTTP/2 SETTINGS frame is an error. initial frame of the HTTP control stream (StreamID 3, see Section 4).
SETTINGS_MAX_FRAME_SIZE: This setting has no equivalent in QUIC. 3.1. Draft Version Identification
Specifying it in the HTTP/2 SETTINGS frame is an error.
SETTINGS_MAX_HEADER_LIST_SIZE Sent in HTTP/2 SETTINGS frame. *RFC Editor's Note:* Please remove this section prior to
publication of a final version of this document.
As with HTTP/2-over-TCP, unknown SETTINGS parameters are tolerated Only implementations of the final, published RFC can identify
but ignored. SETTINGS parameters are acknowledged by the receiving themselves as "hq". Until such an RFC exists, implementations MUST
peer, by sending an empty SETTINGS frame in response with the ACK bit NOT identify themselves using these strings.
set.
4. Sending a request on an HTTP/2-over-QUIC connection Implementations of draft versions of the protocol MUST add the string
"-" and the corresponding draft number to the identifier. For
example, draft-ietf-quic-http-01 is identified using the string "hq-
01".
A high level overview of sending an HTTP/2 request on an established Non-compatible experiments that are based on these draft versions
QUIC connection is as follows, with further details in later sections MUST append the string "-" and an experiment name to the identifier.
of this document. A client should first encode any HTTP headers For example, an experimental implementation based on draft-ietf-quic-
using HPACK [RFC7541] and frame them as HTTP/2 HEADERS frames. These http-09 which reserves an extra stream for unsolicited transmission
are sent on StreamID 3 (see Section 6). The exact layout of the of 1980s pop music might identify itself as "hq-09-rickroll". Note
HEADERS frame is described in Section 6.2 of [RFC7540]. No HTTP/2 that any label MUST conform to the "token" syntax defined in
padding is required: QUIC provides a PADDING frame for this purpose. Section 3.2.6 of [RFC7230]. Experimenters are encouraged to
coordinate their experiments on the quic@ietf.org mailing list.
While HEADERS are sent on stream 3, the mandatory stream identifier 4. Stream Mapping and Usage
in each HEADERS frame indicates the QUIC StreamID on which a
corresponding request body may be sent. If there is no non-header
data, the specified QUIC data stream will never be used.
4.1. Terminating a stream A QUIC stream provides reliable in-order delivery of bytes, but makes
no guarantees about order of delivery with regard to bytes on other
streams. On the wire, data is framed into QUIC STREAM frames, but
this framing is invisible to the HTTP framing layer. A QUIC receiver
buffers and orders received STREAM frames, exposing the data
contained within as a reliable byte stream to the application.
A stream can be terminated in one of three ways: QUIC reserves Stream 1 for crypto operations (the handshake, crypto
config updates). Stream 3 is reserved for sending and receiving HTTP
control frames, and is analogous to HTTP/2's Stream 0.
o the request/response is headers only, in which case a HEADERS When HTTP headers and data are sent over QUIC, the QUIC layer handles
frame with the END_STREAM bit set ends the stream specified in the most of the stream management. An HTTP request/response consumes a
HEADERS frame pair of streams: This means that the client's first request occurs on
QUIC streams 5 and 7, the second on stream 9 and 11, and so on. The
server's first push consumes streams 2 and 4. This amounts to the
second least-significant bit differentiating the two streams in a
request.
o the request/response has headers and body but no trailing headers, The lower-numbered stream is called the message control stream and
in which case the final QUIC STREAM frame will have the FIN bit carries frames related to the request/response, including HEADERS.
set All request control streams are exempt from connection-level flow
control. The higher-numbered stream is the data stream and carries
the request/response body with no additional framing. Note that a
request or response without a body will cause this stream to be half-
closed in the corresponding direction without transferring data.
o the request/response has headers, body, and trailing headers, in Pairs of streams must be utilized sequentially, with no gaps. The
which case the final QUIC STREAM frame will not have the FIN bit data stream MUST be reserved with the QUIC implementation when the
set, and the trailing HEADERS frame will have the END_STREAM bit message control stream is opened or reserved, and MUST be closed
set after transferring the body, or else closed immediately after sending
the request headers if there is no body.
(TODO: Describe mapping of HTTP/2 stream state machine to QUIC stream HTTP does not need to do any separate multiplexing when using QUIC -
state machine.) data sent over a QUIC stream always maps to a particular HTTP
transaction. Requests and responses are considered complete when the
corresponding QUIC streams are closed in the appropriate direction.
5. Writing data to QUIC streams 4.1. Stream 3: Connection Control Stream
A QUIC stream provides reliable in-order delivery of bytes, within Since most connection-level concerns from HTTP/2 will be managed by
that stream. On the wire, data is framed into QUIC STREAM frames, QUIC, the primary use of Stream 3 will be for SETTINGS and PRIORITY
but this framing is invisible to the HTTP/2 layer. A QUIC receiver frames. Stream 3 is exempt from connection-level flow-control.
buffers and orders received STREAM frames, exposing the data
contained within as a reliable byte stream to the application.
Bytes written to Stream 3 must be HTTP/2 HEADERS frames (or other 4.2. HTTP Message Exchanges
HTTP/2 non-data frames), whereas bytes written to data streams should
simply be request or response bodies. No further framing is required
by HTTP/2 (i.e. no HTTP/2 DATA frames are used).
If data arrives on a data stream before the corresponding HEADERS A client sends an HTTP request on a new pair of QUIC streams. A
have arrived on stream 3, then the data is buffered until the HEADERS server sends an HTTP response on the same streams as the request.
arrive.
6. Stream Mapping An HTTP message (request or response) consists of:
When HTTP/2 headers and data are sent over QUIC, the QUIC layer 1. for a response only, zero or more header blocks (a sequence of
handles most of the stream management. HTTP/2 StreamIDs are replaced HEADERS frames with End Header Block set on the last) on the
by QUIC StreamIDs. HTTP/2 does not need to do any explicit stream control stream containing the message headers of informational
framing when using QUIC - data sent over a QUIC stream simply (1xx) HTTP responses (see [RFC7230], Section 3.2 and [RFC7231],
consists of HTTP/2 headers or body. Requests and responses are Section 6.2),
considered complete when the QUIC stream is closed in the
corresponding direction.
Like HTTP/2, QUIC uses odd-numbered StreamIDs for client initiated 2. one header block on the control stream containing the message
streams, and even-numbered IDs for server initiated (i.e. server headers (see [RFC7230], Section 3.2),
push) streams. Unlike HTTP/2 there are a couple of reserved (or
dedicated) StreamIDs in QUIC.
6.1. Reserved Streams 3. the payload body (see [RFC7230], Section 3.3), sent on the data
stream,
StreamID 1 is reserved for crypto operations (the handshake, crypto 4. optionally, one header block on the control stream containing the
config updates), and MUST NOT be used for HTTP/2 headers or body, see trailer-part, if present (see [RFC7230], Section 4.1.2).
[QUIC-TRANSPORT]. StreamID 3 is reserved for sending and receiving
HTTP/2 HEADERS frames. Therefore the first client initiated data
stream has StreamID 5.
There are no reserved server initiated StreamIDs, so the first server The data stream MUST be half-closed immediately after the transfer of
initiated (i.e. server push) stream has an ID of 2, followed by 4, the body. If the message does not contain a body, the corresponding
etc. data stream MUST still be half-closed without transferring any data.
The "chunked" transfer encoding defined in Section 4.1 of [RFC7230]
MUST NOT be used.
6.1.1. Stream 3: headers Trailing header fields are carried in a header block following the
body. Such a header block is a sequence of HEADERS frames with End
Header Block set on the last frame. Header blocks after the first
but before the end of the stream are invalid. These MUST be decoded
to maintain HPACK decoder state, but the resulting output MUST be
discarded.
HTTP/2-over-QUIC uses HPACK header compression as described in An HTTP request/response exchange fully consumes a pair of streams.
[RFC7541]. HPACK was designed for HTTP/2 with the assumption of in- After sending a request, a client closes the streams for sending;
order delivery such as that provided by TCP. A sequence of encoded after sending a response, the server closes its streams for sending
header blocks must arrive (and be decoded) at an endpoint in the same and the QUIC streams are fully closed.
order in which they were encoded. This ensures that the dynamic
state at the two endpoints remains in sync. A server can send a complete response prior to the client sending an
entire request if the response does not depend on any portion of the
request that has not been sent and received. When this is true, a
server MAY request that the client abort transmission of a request
without error by sending a RST_STREAM with an error code of NO_ERROR
after sending a complete response and closing its stream. Clients
MUST NOT discard responses as a result of receiving such a
RST_STREAM, though clients can always discard responses at their
discretion for other reasons.
4.2.1. Header Compression
HTTP/QUIC uses HPACK header compression as described in [RFC7541].
HPACK was designed for HTTP/2 with the assumption of in- order
delivery such as that provided by TCP. A sequence of encoded header
blocks must arrive (and be decoded) at an endpoint in the same order
in which they were encoded. This ensures that the dynamic state at
the two endpoints remains in sync.
QUIC streams provide in-order delivery of data sent on those streams, QUIC streams provide in-order delivery of data sent on those streams,
but there are no guarantees about order of delivery between streams. but there are no guarantees about order of delivery between streams.
To achieve in-order delivery of HEADERS frames in QUIC, they are all To achieve in-order delivery of HEADERS frames in QUIC, the HPACK-
sent on the reserved Stream 3. Data (request/response bodies) which bearing frames contain a counter which can be used to ensure in-order
arrive on other data streams are buffered until the corresponding processing. Data (request/response bodies) which arrive out of order
HEADERS arrive and are read out of Stream 3. are buffered until the corresponding HEADERS arrive.
This does introduce head-of-line blocking: if the packet containing This does introduce head-of-line blocking: if the packet containing
HEADERS for stream N is lost or reordered then stream N+2 cannot be HEADERS for stream N is lost or reordered then the HEADERS for stream
processed until they it has been retransmitted successfully, even N+4 cannot be processed until it has been retransmitted successfully,
though the HEADERS for stream N+2 may have arrived. even though the HEADERS for stream N+4 may have arrived.
Trailing headers (trailers) can also be sent on stream 3. These are DISCUSS: Keep HPACK with HOLB? Redesign HPACK to be order-
sent as HTTP/2 HEADERS frames, but MUST have the END_STREAM bit set, invariant? How much do we need to retain compatibility with
and MUST include a ":final-offset" pseudo-header. Since QUIC HTTP/2's HPACK?
supports out of order delivery, receipt of a HEADERS frame with the
END_STREAM bit set does not guarantee that the entire request/
response body has been fully received. Therefore, the extra ":final-
offset" pseudo-header is included in trailing HEADERS frames to
indicate the total number of body bytes sent on the corresponding
data stream. This is used by the QUIC layer to determine when the
full request has been received and therefore when it is safe to tear
down local stream state. The ":final-offset" pseudo header is
stripped from the HEADERS before passing to the HTTP/2 layer.
6.1.2. Stream states 4.2.2. The CONNECT Method
The mapping of HTTP/2-over-QUIC with potential out of order delivery The pseudo-method CONNECT ([RFC7231], Section 4.3.6) is primarily
of HEADERS frames results in some changes to the HTTP/2 stream state used with HTTP proxies to establish a TLS session with an origin
transition diagram ([RFC7540], Section 5.1}}. Specifically the server for the purposes of interacting with "https" resources. In
transition from "open" to "half closed (remote)", and the transition HTTP/1.x, CONNECT is used to convert an entire HTTP connection into a
from "half closed (local)" to "closed" takes place only when: tunnel to a remote host. In HTTP/2, the CONNECT method is used to
establish a tunnel over a single HTTP/2 stream to a remote host for
similar purposes.
o the peer has explicitly ended the stream via either A CONNECT request in HTTP/QUIC functions in the same manner as in
* an HTTP/2 HEADERS frame with END_STREAM bit set and, in the HTTP/2. The request MUST be formatted as described in [RFC7540],
case of trailing headers, the :final-offset pseudo-header Section 8.3. A CONNECT request that does not conform to these
restrictions is malformed. The message data stream MUST NOT be
closed at the end of the request.
* or a QUIC stream frame with the FIN bit set. A proxy that supports CONNECT establishes a TCP connection
([RFC0793]) to the server identified in the ":authority" pseudo-
header field. Once this connection is successfully established, the
proxy sends a HEADERS frame containing a 2xx series status code to
the client, as defined in [RFC7231], Section 4.3.6, on the message
control stream.
o and the full request or response body has been received. All QUIC STREAM frames on the message data stream correspond to data
sent on the TCP connection. Any QUIC STREAM frame sent by the client
is transmitted by the proxy to the TCP server; data received from the
TCP server is written to the data stream by the proxy. Note that the
size and number of TCP segments is not guaranteed to map predictably
to the size and number of QUIC STREAM frames.
7. Stream Priorities The TCP connection can be closed by either peer. When the client
half-closes the data stream, the proxy will set the FIN bit on its
connection to the TCP server. When the proxy receives a packet with
the FIN bit set, it will half-close the corresponding data stream.
TCP connections which remain half-closed in a single direction are
not invalid, but are often handled poorly by servers, so clients
SHOULD NOT half-close connections on which they are still expecting
data.
HTTP/2-over-QUIC uses the HTTP/2 priority scheme described in A TCP connection error is signaled with RST_STREAM. A proxy treats
[RFC7540] Section 5.3. In the HTTP/2 priority scheme, a given stream any error in the TCP connection, which includes receiving a TCP
can be designated as dependent upon another stream, which expresses segment with the RST bit set, as a stream error of type
the preference that the latter stream (the "parent" stream) be HTTP_CONNECT_ERROR (Section 6.1). Correspondingly, a proxy MUST send
allocated resources before the former stream (the "dependent" a TCP segment with the RST bit set if it detects an error with the
stream). Taken together, the dependencies across all streams in a stream or the QUIC connection.
connection form a dependency tree. The structure of the dependency
tree changes as HTTP/2 HEADERS and PRIORITY frames add, remove, or 4.3. Stream Priorities
change the dependency links between streams.
HTTP/QUIC uses the priority scheme described in [RFC7540]
Section 5.3. In this priority scheme, a given stream can be
designated as dependent upon another stream, which expresses the
preference that the latter stream (the "parent" stream) be allocated
resources before the former stream (the "dependent" stream). Taken
together, the dependencies across all streams in a connection form a
dependency tree. The structure of the dependency tree changes as
HEADERS and PRIORITY frames add, remove, or change the dependency
links between streams.
Implicit in this scheme is the notion of in-order delivery of Implicit in this scheme is the notion of in-order delivery of
priority changes (i.e., dependency tree mutations): since operations priority changes (i.e., dependency tree mutations): since operations
on the dependency tree such as reparenting a subtree are not on the dependency tree such as reparenting a subtree are not
commutative, both sender and receiver must apply them in the same commutative, both sender and receiver must apply them in the same
order to ensure that both sides have a consistent view of the stream order to ensure that both sides have a consistent view of the stream
dependency tree. HTTP/2 specifies priority assignments in PRIORITY dependency tree. HTTP/2 specifies priority assignments in PRIORITY
frames and (optionally) in HEADERS frames. To achieve in-order frames and (optionally) in HEADERS frames. To achieve in-order
delivery of HTTP/2 priority changes in HTTP/2-over-QUIC, HTTP/2 delivery of priority changes in HTTP/QUIC, PRIORITY frames are sent
PRIORITY frames, in addition to HEADERS frames, are also sent on on the connection control stream and the PRIORITY section is removed
reserved stream 3. The semantics of the Stream Dependency, Weight, E from the HEADERS frame. The semantics of the Stream Dependency,
flag, and (for HEADERS frames) PRIORITY flag are the same as in Weight, E flag, and (for HEADERS frames) PRIORITY flag are the same
HTTP/2-over-TCP. as in HTTP/2.
Since HEADERS and PRIORITY frames are sent on a different stream than
the STREAM frames for the streams they reference, they may be
delivered out-of-order with respect to the STREAM frames. There is
no special handling for this-the receiver should simply assign
resources according to the most recent stream priority information
that it has received.
ALTERNATIVE DESIGN: if the core QUIC protocol implements priorities, For consistency's sake, all PRIORITY frames MUST refer to the message
then this document should map the HTTP/2 priorities scheme to that control stream of the dependent request, not the data stream.
provided by the core protocol. This would likely involve prohibiting
the sending of HTTP/2 PRIORITY frames and setting of the PRIORITY
flag in HTTP/2 HEADERS frames, to avoid conflicting directives.
8. Flow Control 4.4. Flow Control
QUIC provides stream and connection level flow control, similar in QUIC provides stream and connection level flow control, similar in
principle to HTTP/2's flow control but with some implementation principle to HTTP/2's flow control but with some implementation
differences. As flow control is handled by QUIC, the HTTP/2 mapping differences. As flow control is handled by QUIC, the HTTP mapping
need not concern itself with maintaining flow control state, or how/ need not concern itself with maintaining flow control state. The
when to send flow control frames to the peer. The HTTP/2 mapping HTTP mapping MUST NOT send WINDOW_UPDATE frames at the HTTP level.
must not send HTTP/2 WINDOW_UPDATE frames.
The initial flow control window sizes (stream and connection) are
communicated during the crypto handshake (see Section 3). Setting
these values to the maximum size (2^31 - 1) effectively disables flow
control.
Relatively small initial windows can be used, as QUIC will attempt to
auto-tune the flow control windows based on usage. See
[QUIC-TRANSPORT] for more details.
9. Server Push 4.5. Server Push
HTTP/2-over-QUIC supports HTTP/2 server push. During connection HTTP/QUIC supports server push as described in [RFC7540]. During
establishment, the client indicates whether or it is willing to connection establishment, the client indicates whether it is willing
receive server pushes via the SETTINGS_ENABLE_PUSH setting in the to receive server pushes via the SETTINGS_ENABLE_PUSH setting in the
HTTP/2 SETTINGS frame (see Section 3), which defaults to 1 (true). SETTINGS frame (see Section 3), which defaults to 1 (true).
As with server push for HTTP/2-over-TCP, the server initiates a As with server push for HTTP/2, the server initiates a server push by
server push by sending an HTTP/2 PUSH_PROMISE frame containing the sending a PUSH_PROMISE frame containing the StreamID of the stream to
StreamID of the stream to be pushed, as well as request header fields be pushed, as well as request header fields attributed to the
attributed to the request. The PUSH_PROMISE frame is sent on stream request. The PUSH_PROMISE frame is sent on the control stream of the
3, to ensure proper ordering with respect to other HEADERS and non- associated (client-initiated) request, while the Promised Stream ID
data frames. Within the PUSH_PROMISE frame, the StreamID in the field specifies the Stream ID of the control stream for the server-
common HTTP/2 frame header indicates the associated (client- initiated request.
initiated) stream for the new push stream, while the Promised Stream
ID field specifies the StreamID of the new push stream.
The server push response is conveyed in the same way as a non-server- The server push response is conveyed in the same way as a non-server-
push response, with response headers and (if present) trailers push response, with response headers and (if present) trailers
carried by HTTP/2 HEADERS frames sent on reserved stream 3, and carried by HEADERS frames sent on the control stream, and response
response body (if any) sent via QUIC stream frames on the stream body (if any) sent via the corresponding data stream.
specified in the corresponding PUSH_PROMISE frame.
10. Error Codes 5. HTTP Framing Layer
Many framing concepts from HTTP/2 can be elided away on QUIC, because
the transport deals with them. Because frames are already on a
stream, they can omit the stream number. Because frames do not block
multiplexing (QUIC's multiplexing occurs below this layer), the
support for variable-maximum-length packets can be removed. Because
stream termination is handled by QUIC, an END_STREAM flag is not
required.
Frames are used only on the connection (stream 3) and message
(streams 5, 9, etc.) control streams. Other streams carry data
payload and are not framed at the HTTP layer.
Frame payloads are largely drawn from [RFC7540]. However, QUIC
includes some features (e.g. flow control) which are also present in
HTTP/2. In these cases, the HTTP mapping need not re-implement them.
As a result, some frame types are not required when using QUIC.
Where an HTTP/2-defined frame is no longer used, the frame ID is
reserved in order to maximize portability between HTTP/2 and HTTP/
QUIC implementations. However, equivalent frames between the two
mappings are not necessarily identical.
This section describes HTTP framing in QUIC and highlights
differences from HTTP/2 framing.
5.1. Frame Layout
All frames have the following format:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length (16) | Type (8) | Flags (8) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Frame Payload (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
HTTP/QUIC frame format
5.2. Frame Definitions
5.2.1. DATA
DATA frames do not exist. Frame type 0x0 is reserved.
5.2.2. HEADERS
The HEADERS frame (type=0x1) is used to carry part of a header set,
compressed using HPACK [RFC7541]. Because HEADERS frames from
different streams will be delivered out-of-order and priority-changes
are not commutative, the PRIORITY region of HEADERS is not supported.
A separate PRIORITY frame MUST be used.
Padding MUST NOT be used. The flags defined are:
Reserved (0x1): Reserved for HTTP/2 compatibility.
End Header Block (0x4): This frame concludes a header block.
Reserved (0x8): Reserved for HTTP/2 compatibility.
Reserved (0x20): Reserved for HTTP/2 compatibility.
A HEADERS frame with the Reserved bits set MUST be treated as a
connection error of type HTTP_MALFORMED_HEADERS.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence? (16) | Header Block Fragment (*)...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
HEADERS frame payload
The HEADERS frame payload has the following fields:
Sequence Number: Present only on the first frame of a header block
sequence. This MUST be set to zero on the first header block
sequence, and incremented on each header block.
The next frame on the same stream after a HEADERS frame without the
EHB flag set MUST be another HEADERS frame. A receiver MUST treat
the receipt of any other type of frame as a stream error of type
HTTP_INTERRUPTED_HEADERS. (Note that QUIC can intersperse data from
other streams between frames, or even during transmission of frames,
so multiplexing is not blocked by this requirement.)
A full header block is contained in a sequence of zero or more
HEADERS frames without EHB set, followed by a HEADERS frame with EHB
set.
On receipt, header blocks (HEADERS, PUSH_PROMISE) MUST be processed
by the HPACK decoder in sequence. If a block is missing, all
subsequent HPACK frames MUST be held until it arrives, or the
connection terminated.
5.2.3. PRIORITY
The PRIORITY (type=0x02) frame specifies the sender-advised priority
of a stream and is substantially different from [RFC7540]. In order
to support ordering, it MUST be sent only on the connection control
stream. The format has been modified to accommodate not being sent
on-stream and the larger stream ID space of QUIC.
The flags defined are:
E (0x01): Indicates that the stream dependency is exclusive (see
[RFC7540] Section 5.3).
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prioritized Stream (32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Dependent Stream (32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Weight (8) |
+-+-+-+-+-+-+-+-+
HEADERS frame payload
The HEADERS frame payload has the following fields:
Prioritized Stream: A 32-bit stream identifier for the message
control stream whose priority is being updated.
Stream Dependency: A 32-bit stream identifier for the stream that
this stream depends on (see Section 4.3 and {!RFC7540}}
Section 5.3).
Weight: An unsigned 8-bit integer representing a priority weight for
the stream (see [RFC7540] Section 5.3). Add one to the value to
obtain a weight between 1 and 256.
A PRIORITY frame MUST have a payload length of nine octets. A
PRIORITY frame of any other length MUST be treated as a connection
error of type HTTP_MALFORMED_PRIORITY.
5.2.4. RST_STREAM
RST_STREAM frames do not exist, since QUIC provides stream lifecycle
management. Frame type 0x3 is reserved.
5.2.5. SETTINGS
The SETTINGS frame (type=0x4) conveys configuration parameters that
affect how endpoints communicate, such as preferences and constraints
on peer behavior, and is substantially different from [RFC7540].
Individually, a SETTINGS parameter can also be referred to as a
"setting".
SETTINGS parameters are not negotiated; they describe characteristics
of the sending peer, which can be used by the receiving peer.
However, a negotiation can be implied by the use of SETTINGS - a peer
uses SETTINGS to advertise a set of supported values. The recipient
can then choose which entries from this list are also acceptable and
proceed with the value it has chosen. (This choice could be
announced in a field of an extension frame, or in its own value in
SETTINGS.)
Different values for the same parameter can be advertised by each
peer. For example, a client might permit a very large HPACK state
table while a server chooses to use a small one to conserve memory.
A SETTINGS frame MAY be sent at any time by either endpoint over the
lifetime of the connection.
Each parameter in a SETTINGS frame replaces any existing value for
that parameter. Parameters are processed in the order in which they
appear, and a receiver of a SETTINGS frame does not need to maintain
any state other than the current value of its parameters. Therefore,
the value of a SETTINGS parameter is the last value that is seen by a
receiver.
The SETTINGS frame defines the following flag:
REQUEST_ACK (0x1): When set, bit 0 indicates that this frame
contains values which the sender wants to know were understood and
applied. For more information, see Section 5.2.5.3.
The payload of a SETTINGS frame consists of zero or more parameters,
each consisting of an unsigned 16-bit setting identifier and a
length-prefixed binary value.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier (16) |B| Length (15) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Contents (?) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: SETTINGS value format
A zero-length content indicates that the setting value is a Boolean
given by the B bit. If Length is not zero, the B bit MUST be zero,
and MUST be ignored by receivers. The initial value of each setting
is "false" unless otherwise specified by the definition of the
setting.
Non-zero-length values MUST be compared against the remaining length
of the SETTINGS frame. Any value which purports to cross the end of
the frame MUST cause the SETTINGS frame to be considered malformed
and trigger a connection error.
An implementation MUST ignore the contents for any SETTINGS
identifier it does not understand.
SETTINGS frames always apply to a connection, never a single stream,
and MUST only be sent on the connection control stream (Stream 3).
If an endpoint receives an SETTINGS frame whose stream identifier
field is anything other than 0x0, the endpoint MUST respond with a
connection error of type HTTP_SETTINGS_ON_WRONG_STREAM.
The SETTINGS frame affects connection state. A badly formed or
incomplete SETTINGS frame MUST be treated as a connection error
(Section 5.4.1) of type HTTP_MALFORMED_SETTINGS.
5.2.5.1. Integer encoding
Settings which are integers are transmitted in network byte order.
Leading zero octets are permitted, but implementations SHOULD use
only as many bytes as are needed to represent the value. An integer
MUST NOT be represented in more bytes than would be used to transfer
the maximum permitted value.
5.2.5.2. Defined SETTINGS Parameters
Some transport-level options that HTTP/2 specifies via the SETTINGS
frame are superseded by QUIC transport parameters in HTTP/QUIC.
Below is a listing of how each HTTP/2 SETTINGS parameter is mapped:
SETTINGS_HEADER_TABLE_SIZE: An integer with a maximum value of 2^32
- 1.
SETTINGS_ENABLE_PUSH: Transmitted as a Boolean. The default remains
"true" as specified in [RFC7540].
SETTINGS_MAX_CONCURRENT_STREAMS: QUIC requires the maximum number of
incoming streams per connection to be specified in the initial
crypto handshake, using the "MSPC" tag. Specifying
SETTINGS_MAX_CONCURRENT_STREAMS in the SETTINGS frame is an error.
SETTINGS_INITIAL_WINDOW_SIZE: QUIC requires both stream and
connection flow control window sizes to be specified in the
initial crypto handshake, using the "SFCW" and "CFCW" tags,
respectively. Specifying SETTINGS_INITIAL_WINDOW_SIZE in the
SETTINGS frame is an error.
SETTINGS_MAX_FRAME_SIZE: This setting has no equivalent in QUIC.
Specifying it in the SETTINGS frame is an error.
SETTINGS_MAX_HEADER_LIST_SIZE: An integer with a maximium value of
2^32 - 1.
5.2.5.3. Settings Synchronization
Some values in SETTINGS benefit from or require an understanding of
when the peer has received and applied the changed parameter values.
In order to provide such synchronization timepoints, the recipient of
a SETTINGS frame MUST apply the updated parameters as soon as
possible upon receipt. The values in the SETTINGS frame MUST be
processed in the order they appear, with no other frame processing
between values. Unsupported parameters MUST be ignored.
Once all values have been processed, if the REQUEST_ACK flag was set,
the recipient MUST emit the following frames:
o On the connection control stream, a SETTINGS_ACK frame
(Section 5.2.11) listing the identifiers whose values were not
understood.
o On each request control stream which is not in the "half-closed
(local)" or "closed" state, an empty SETTINGS_ACK frame.
The SETTINGS_ACK frame on the connection control stream contains the
highest stream number which was open at the time the SETTINGS frame
was received. All streams with higher numbers can safely be assumed
to have the new settings in effect when they open.
For already-open streams including the connection control stream, the
SETTINGS_ACK frame indicates the point at which the new settings took
effect, if they did so before the peer half-closed the stream. If
the peer closed the stream before receiving the SETTINGS frame, the
previous settings were in effect for the full lifetime of that
stream.
In certain conditions, the SETTINGS_ACK frame can be the first frame
on a given stream - this simply indicates that the new settings apply
from the beginning of that stream.
If the sender of a SETTINGS frame with the REQUEST_ACK flag set does
not receive full acknowledgement within a reasonable amount of time,
it MAY issue a connection error (Section 6) of type
HTTP_SETTINGS_TIMEOUT. A full acknowledgement has occurred when:
o All previous SETTINGS frames have been fully acknowledged,
o A SETTINGS_ACK frame has been received on the connection control
stream,
o All message control streams with a Stream ID through those given
in the SETTINGS_ACK frame have either closed or received a
SETTINGS_ACK frame.
5.2.6. PUSH_PROMISE
The PUSH_PROMISE frame (type=0x05) is used to carry a request header
set from server to client, as in HTTP/2. It defines no flags.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Promised Stream ID (32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence? (16) | Header Block (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
PUSH_PROMISE frame payload
The payload consists of:
Promised Stream ID: A 32-bit Stream ID indicating the QUIC stream on
which the response headers will be sent. (The response body
stream is implied by the headers stream, as defined in Section 4.)
HPACK Sequence: A sixteen-bit counter, equivalent to the Sequence
field in HEADERS
Payload: HPACK-compressed request headers for the promised response.
TODOs:
o QUIC stream space may be enlarged; would need to redefine Promised
Stream field in this case.
o No CONTINUATION - HEADERS have EHB; do we need it here?
5.2.7. PING
PING frames do not exist, since QUIC provides equivalent
functionality. Frame type 0x6 is reserved.
5.2.8. GOAWAY frame
GOAWAY frames do not exist, since QUIC provides equivalent
functionality. Frame type 0x7 is reserved.
5.2.9. WINDOW_UPDATE frame
WINDOW_UPDATE frames do not exist, since QUIC provides equivalent
functionality. Frame type 0x8 is reserved.
5.2.10. CONTINUATION frame
CONTINUATION frames do not exist, since larger supported HEADERS/
PUSH_PROMISE frames provide equivalent functionality. Frame type 0x9
is reserved.
5.2.11. SETTINGS_ACK Frame
The SETTINGS_ACK frame (id = 0x0b) acknowledges receipt and
application of specific values in the peer's SETTINGS frame.
Depending on the stream where it is sent, it takes two different
forms.
On the connection control stream, it contains information about how
and when the sender has processed the most recently-received SETTINGS
frame, and has the following payload:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Highest Local Stream (32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Highest Remote Stream (32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unrecognized Identifiers (*) ...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: SETTINGS_ACK connection control stream format
Highest Local Stream (32 bits): The highest locally-initiated Stream
ID which is not in the "idle" state
Highest Remote Stream (32 bits): The highest peer-initiated Stream
ID which is not in the "idle" state
Unrecognized Identifiers: A list of 16-bit SETTINGS identifiers
which the sender has not understood and therefore ignored. This
list MAY be empty.
On message control streams, the SETTINGS_ACK frame carries no
payload, and is strictly a synchronization marker for settings
application. See Section 5.2.5.3 for more detail. A SETTINGS_ACK
frame with a non-zero length MUST be treated as a connection error of
type HTTP_MALFORMED_SETTINGS_ACK.
On the connection control stream, the SETTINGS_ACK frame MUST have a
length which is a multiple of two octets. A SETTINGS_ACK frame of
any other length MUST be treated as a connection error of type
HTTP_MALFORMED_SETTINGS_ACK.
6. Error Handling
This section describes the specific error codes defined by HTTP and
the mapping of HTTP/2 error codes into the QUIC error code space.
6.1. HTTP-Defined QUIC Error Codes
QUIC allocates error codes 0x0000-0x3FFF to application protocol
definition. The following error codes are defined by HTTP for use in
QUIC RST_STREAM, GOAWAY, and CONNECTION_CLOSE frames.
HTTP_SETTINGS_TIMEOUT (0x00): After sending a SETTINGS frame which
requested acknowledgement, the acknowledgement was not completed
(see Section 5.2.5.3) in a timely manner.
HTTP_PUSH_REFUSED (0x01): The server has attempted to push content
which the client will not accept on this connection.
HTTP_INTERNAL_ERROR (0x02): An internal error has occurred in the
HTTP stack.
HTTP_PUSH_ALREADY_IN_CACHE (0x03): The server has attempted to push
content which the client has cached.
HTTP_REQUEST_CANCELLED (0x04): The client no longer needs the
requested data.
HTTP_HPACK_DECOMPRESSION_FAILED (0x05): HPACK failed to decompress a
frame and cannot continue.
HTTP_CONNECT_ERROR (0x06): The connection established in response to
a CONNECT request was reset or abnormally closed.
HTTP_EXCESSIVE_LOAD (0x07): The endpoint detected that its peer is
exhibiting a behavior that might be generating excessive load.
HTTP_VERSION_FALLBACK (0x08): The requested operation cannot be
served over HTTP/QUIC. The peer should retry over HTTP/2.
HTTP_MALFORMED_HEADERS (0x09): A HEADERS frame has been received
with an invalid format.
HTTP_MALFORMED_PRIORITY (0x0A): A HEADERS frame has been received
with an invalid format.
HTTP_MALFORMED_SETTINGS (0x0B): A HEADERS frame has been received
with an invalid format.
HTTP_MALFORMED_PUSH_PROMISE (0x0C): A HEADERS frame has been
received with an invalid format.
HTTP_MALFORMED_SETTINGS_ACK (0x0D): A HEADERS frame has been
received with an invalid format.
HTTP_INTERRUPTED_HEADERS (0x0E): A HEADERS frame without the End
Header Block flag was followed by a frame other than HEADERS.
HTTP_SETTINGS_ON_WRONG_STREAM (0x0F): A SETTINGS frame was received
on a request control stream.
6.2. Mapping HTTP/2 Error Codes
The HTTP/2 error codes defined in Section 7 of [RFC7540] map to QUIC The HTTP/2 error codes defined in Section 7 of [RFC7540] map to QUIC
error codes as follows: error codes as follows:
NO_ERROR (0x0): Maps to QUIC_NO_ERROR NO_ERROR (0x0): QUIC_NO_ERROR
PROTOCOL_ERROR (0x1): No single mapping?
INTERNAL_ERROR (0x2) QUIC_INTERNAL_ERROR? (not currently defined in PROTOCOL_ERROR (0x1): No single mapping. See new HTTP_MALFORMED_*
core protocol spec) error codes defined in Section 6.1.
FLOW_CONTROL_ERROR (0x3): QUIC_FLOW_CONTROL_RECEIVED_TOO_MUCH_DATA? INTERNAL_ERROR (0x2) HTTP_INTERNAL_ERROR in Section 6.1.
(not currently defined in core protocol spec)
SETTINGS_TIMEOUT (0x4): (depends on whether we support SETTINGS FLOW_CONTROL_ERROR (0x3): Not applicable, since QUIC handles flow
acks) control. Would provoke a QUIC_FLOW_CONTROL_RECEIVED_TOO_MUCH_DATA
from the QUIC layer.
STREAM_CLOSED (0x5): QUIC_STREAM_DATA_AFTER_TERMINATION SETTINGS_TIMEOUT (0x4): HTTP_SETTINGS_TIMEOUT in Section 6.1.
FRAME_SIZE_ERROR (0x6) QUIC_INVALID_FRAME_DATA STREAM_CLOSED (0x5): Not applicable, since QUIC handles stream
management. Would provoke a QUIC_STREAM_DATA_AFTER_TERMINATION
from the QUIC layer.
REFUSED_STREAM (0x7): ? FRAME_SIZE_ERROR (0x6) No single mapping. See new error codes
defined in Section 6.1.
CANCEL (0x8): ? REFUSED_STREAM (0x7): Not applicable, since QUIC handles stream
management. Would provoke a QUIC_TOO_MANY_OPEN_STREAMS from the
QUIC layer.
COMPRESSION_ERROR (0x9): QUIC_DECOMPRESSION_FAILURE (not currently CANCEL (0x8): HTTP_REQUEST_CANCELLED in Section 6.1.
defined in core spec)
CONNECT_ERROR (0xa): ? (depends whether we decide to support COMPRESSION_ERROR (0x9): HTTP_HPACK_DECOMPRESSION_FAILED in
CONNECT) Section 6.1.
ENHANCE_YOUR_CALM (0xb): ? CONNECT_ERROR (0xa): HTTP_CONNECT_ERROR in Section 6.1.
INADEQUATE_SECURITY (0xc): QUIC_HANDSHAKE_FAILED, ENHANCE_YOUR_CALM (0xb): HTTP_EXCESSIVE_LOAD in Section 6.1.
QUIC_CRYPTO_NO_SUPPORT
HTTP_1_1_REQUIRED (0xd): ? INADEQUATE_SECURITY (0xc): Not applicable, since QUIC is assumed to
provide sufficient security on all connections.
HTTP_1_1_REQUIRED (0xd): HTTP_VERSION_FALLBACK in Section 6.1.
TODO: fill in missing error code mappings. TODO: fill in missing error code mappings.
11. Other HTTP/2 frames 7. Security Considerations
QUIC includes some features (e.g. flow control) which are also The security considerations of HTTP over QUIC should be comparable to
present in HTTP/2. In these cases the HTTP/2 mapping need not re- those of HTTP/2.
implement them. As a result some HTTP/2 frame types are not required
when using QUIC, as they either are directly implemented in the QUIC
layer, or their functionality is provided via other means. This
section of the document describes these cases.
11.1. GOAWAY frame The modified SETTINGS format contains nested length elements, which
could pose a security risk to an uncautious implementer. A SETTINGS
frame parser MUST ensure that the length of the frame exactly matches
the length of the settings it contains.
QUIC has its own GOAWAY frame, and QUIC implementations may to expose 8. IANA Considerations
the sending of a GOAWAY to the application. The semantics of sending
a GOAWAY in QUIC are identical to HTTP/2: an endpoint sending a
GOAWAY will continue processing open streams, but will not accept
newly created streams.
QUIC's GOAWAY frame is described in detail in the [QUIC-TRANSPORT]. 8.1. Registration of HTTP/QUIC Identification String
11.2. PING frame This document creates a new registration for the identification of
HTTP/QUIC in the "Application Layer Protocol Negotiation (ALPN)
Protocol IDs" registry established in [RFC7301].
QUIC has its own PING frame, which is currently exposed to the The "hq" string identifies HTTP/QUIC:
application. QUIC clients send periodic PINGs to servers if there
are no currently active data streams on the connection.
QUIC's PING frame is described in detail in the [QUIC-TRANSPORT]. Protocol: HTTP over QUIC
11.3. PADDING frame Identification Sequence: 0x68 0x71 ("hq")
There is no HTTP/2 padding in this mapping; padding is instead Specification: This document
provided at the QUIC layer by including QUIC PADDING frames in a
packet payload. An HTTP/2 over QUIC mapping should treat any HTTP/2
level padding as an error, to avoid any possibility of inconsistent
flow control states between endpoints (e.g. client sends HTTP/2
padding, counts it against flow control, server ignores).
12. Security Considerations 8.2. Registration of Version Hint Alt-Svc Parameter
The security considerations of HTTP over QUIC should be comparable to This document creates a new registration for version-negotiation
those of HTTP/2. hints in the "Hypertext Transfer Protocol (HTTP) Alt-Svc Parameter"
registry established in [RFC7838].
13. IANA Considerations Parameter: "v"
This document has no IANA actions. Yet. Specification: This document, Section 2.1
14. Normative References 8.3. Existing Frame Types
This document adds two new columns to the "HTTP/2 Frame Type"
registry defined in [RFC7540]:
Supported Protocols: Indicates which associated protocols use the
frame type. Values MUST be one of:
* "HTTP/2 only"
* "HTTP/QUIC only"
* "Both"
HTTP/QUIC Specification: Indicates where this frame's behavior over
QUIC is defined; required if the frame is supported over QUIC.
Values for existing registrations are assigned by this document:
+---+---------------+---------------------+-------------------------+
| | Frame Type | Supported Protocols | HTTP/QUIC Specification |
+---+---------------+---------------------+-------------------------+
| | DATA | HTTP/2 only | N/A |
| | | | |
| | HEADERS | Both | Section 5.2.2 |
| | | | |
| | PRIORITY | Both | Section 5.2.3 |
| | | | |
| | RST_STREAM | HTTP/2 only | N/A |
| | | | |
| | SETTINGS | Both | Section 5.2.5 |
| | | | |
| | PUSH_PROMISE | Both | Section 5.2.6 |
| | | | |
| | PING | HTTP/2 only | N/A |
| | | | |
| | GOAWAY | HTTP/2 only | N/A |
| | | | |
| | WINDOW_UPDATE | HTTP/2 only | N/A |
| | | | |
| | CONTINUATION | HTTP/2 only | N/A |
+---+---------------+---------------------+-------------------------+
The "Specification" column is renamed to "HTTP/2 specification" and
is only required if the frame is supported over HTTP/2.
8.4. New Frame Types
This document adds one new entry to the "HTTP/2 Frame Type" registry
defined in [RFC7540]:
Frame Type: SETTINGS_ACK
Code: 0x0b
HTTP/2 Specification: N/A
Supported Protocols: HTTP/QUIC only
HTTP/QUIC Specification: Section 5.2.11
9. References
9.1. Normative References
[QUIC-TLS] [QUIC-TLS]
Thomson, M., Ed. and S. Turner, Ed, Ed., "Using Transport Thomson, M., Ed. and S. Turner, Ed, Ed., "Using Transport
Layer Security (TLS) to Secure QUIC", November 2016. Layer Security (TLS) to Secure QUIC".
[QUIC-TRANSPORT] [QUIC-TRANSPORT]
Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
Multiplexed and Secure Transport", November 2016. Multiplexed and Secure Transport".
[RFC0793] Postel, J., "Transmission Control Protocol", STD 7,
RFC 793, DOI 10.17487/RFC0793, September 1981,
<http://www.rfc-editor.org/info/rfc793>.
[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,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014,
<http://www.rfc-editor.org/info/rfc7230>.
[RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
DOI 10.17487/RFC7231, June 2014,
<http://www.rfc-editor.org/info/rfc7231>.
[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, DOI 10.17487/RFC7540, May 2015,
<http://www.rfc-editor.org/info/rfc7540>. <http://www.rfc-editor.org/info/rfc7540>.
[RFC7541] Peon, R. and H. Ruellan, "HPACK: Header Compression for [RFC7541] Peon, R. and H. Ruellan, "HPACK: Header Compression for
HTTP/2", RFC 7541, DOI 10.17487/RFC7541, May 2015, HTTP/2", RFC 7541, DOI 10.17487/RFC7541, May 2015,
<http://www.rfc-editor.org/info/rfc7541>. <http://www.rfc-editor.org/info/rfc7541>.
[RFC7838] Nottingham, M., McManus, P., and J. Reschke, "HTTP
Alternative Services", RFC 7838, DOI 10.17487/RFC7838,
April 2016, <http://www.rfc-editor.org/info/rfc7838>.
9.2. Informative References
[RFC7301] Friedl, S., Popov, A., Langley, A., and E. Stephan,
"Transport Layer Security (TLS) Application-Layer Protocol
Negotiation Extension", RFC 7301, DOI 10.17487/RFC7301,
July 2014, <http://www.rfc-editor.org/info/rfc7301>.
Appendix A. Contributors Appendix A. Contributors
The original authors of this specification were Robbie Shade and Mike The original authors of this specification were Robbie Shade and Mike
Warres. Warres.
Appendix B. Change Log
*RFC Editor's Note:* Please remove this section prior to
publication of a final version of this document.
B.1. Since draft-ietf-quic-http-00:
o Changed "HTTP/2-over-QUIC" to "HTTP/QUIC" throughout
o Changed from using HTTP/2 framing within Stream 3 to new framing
format and two-stream-per-request model
o Adopted SETTINGS format from draft-bishop-httpbis-extended-
settings-01
o Reworked SETTINGS_ACK to account for indeterminate inter-stream
order.
o Described CONNECT pseudo-method
o Updated ALPN token and Alt-Svc guidance
o Application-layer-defined error codes
B.2. Since draft-shade-quic-http2-mapping-00:
o Adopted as base for draft-ietf-quic-http.
o Updated authors/editors list.
Author's Address Author's Address
Mike Bishop (editor) Mike Bishop (editor)
Microsoft Microsoft
Email: Mike.Bishop@microsoft.com Email: Michael.Bishop@microsoft.com
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