wdiff draft-ietf-quic-http-00.txt draft-ietf-quic-http-01.txt

QUIC M. Bishop, Ed.
Internet-Draft Microsoft
Intended status: Standards Track November 28, 2016 January 14, 2017
Expires: June 1, July 18, 2017

Hypertext Transfer Protocol (HTTP) over QUIC
draft-ietf-quic-http-00
draft-ietf-quic-http-01

Abstract

The QUIC transport protocol has several features that are desirable
in a transport for HTTP/2, HTTP, such as stream multiplexing, per-stream flow
control, and low-latency connection establishment. This document
describes a mapping of HTTP/2 HTTP semantics over QUIC. Specifically, this
document identifies HTTP/2 features that are subsumed by QUIC, and
describes how the other features can be 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

This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.

Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."

This Internet-Draft will expire on June 1, July 18, 2017.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 3
1.1. Notational Conventions . . . . . . . . . . . . . . . . . 2 3
2. QUIC advertisement Advertisement . . . . . . . . . . . . . . . . . . . . . 3
2.1. QUIC Version Hints . . . . . . . . . . . . . . . . . . . 4
3. Connection establishment Establishment . . . . . . . . . . . . . . . . . . 3 4
3.1. Draft Version Identification . . . . . . . . . . . . . . 5
4. Sending a request on an HTTP/2-over-QUIC connection Stream Mapping and Usage . . . . . 4 . . . . . . . . . . . . . 5
4.1. Terminating a stream Stream 3: Connection Control Stream . . . . . . . . . . . 6
4.2. HTTP Message Exchanges . . . . . . . 4
5. Writing data to QUIC streams . . . . . . . . . . 6
4.2.1. Header Compression . . . . . . 5
6. . . . . . . . . . . . 7
4.2.2. The CONNECT Method . . . . . . . . . . . . . . . . . 8
4.3. Stream Mapping Priorities . . . . . . . . . . . . . . . . . . . . 9
4.4. Flow Control . . . 5
6.1. Reserved Streams . . . . . . . . . . . . . . . . . . . 9
4.5. Server Push . 5
6.1.1. Stream 3: headers . . . . . . . . . . . . . . . . . . 6
6.1.2. Stream states . . . . 9
5. HTTP Framing Layer . . . . . . . . . . . . . . . . 6
7. Stream Priorities . . . . . 10
5.1. Frame Layout . . . . . . . . . . . . . . . . . 7
8. Flow Control . . . . . 10
5.2. Frame Definitions . . . . . . . . . . . . . . . . . . . 8
9. Server Push . 11
5.2.1. DATA . . . . . . . . . . . . . . . . . . . . . . . . 8
10. Error Codes 11
5.2.2. HEADERS . . . . . . . . . . . . . . . . . . . . . . . 11
5.2.3. PRIORITY . . 8
11. Other HTTP/2 frames . . . . . . . . . . . . . . . . . . . . 12
5.2.4. RST_STREAM . 9
11.1. GOAWAY frame . . . . . . . . . . . . . . . . . . . . 13
5.2.5. SETTINGS . . 9
11.2. . . . . . . . . . . . . . . . . . . . . 13
5.2.6. PUSH_PROMISE . . . . . . . . . . . . . . . . . . . . 16
5.2.7. PING . . . . . . . . . . . . . . . . . . . . . . . . 17
5.2.8. GOAWAY frame . . . . . . . . . . . . . . . . . . . . 17
5.2.9. WINDOW_UPDATE frame . . . 10
11.3. PADDING . . . . . . . . . . . . . . 17
5.2.10. CONTINUATION frame . . . . . . . . . . . . . . . . . 17
5.2.11. SETTINGS_ACK Frame . . . . 10
12. . . . . . . . . . . . . . 18
6. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 19
6.1. HTTP-Defined QUIC Error Codes . . . . . . . . . . . . . . 19
6.2. Mapping HTTP/2 Error Codes . . . . . . . . . . . . . . . 20

7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
13. 21
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
14. 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 . . 10 . . . . . . . . . . . . . . . 24
Appendix A. Contributors . . . . . . . . . . . . . . . . . . . . 11 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 . . . . . . . . . . . . . . . . . . . . . . . . 11 25

1. Introduction

The QUIC transport protocol has several features that are desirable
in a transport for HTTP/2, HTTP, such as stream multiplexing, per-stream flow
control, and low-latency connection establishment. This document
describes a mapping of HTTP/2 HTTP semantics over QUIC. QUIC, drawing heavily on
the existing TCP mapping, HTTP/2. Specifically, this document
identifies HTTP/2 features that are subsumed by QUIC, and describes
how the other features can be implemented atop QUIC.

QUIC is described in [QUIC-TRANSPORT]. For a full description of
HTTP/2, see [RFC7540].

1.1. Notational Conventions

The words "MUST", "MUST NOT", "SHOULD", and "MAY" are used in this
document. It's not shouting; when they are capitalized, they have
the special meaning defined in [RFC2119].

2. QUIC advertisement Advertisement

A server advertises that it can speak HTTP/2-over-QUIC HTTP/QUIC via the Alt-Svc
([RFC7838]) HTTP response header (or the semantically equivalent Alt-
Svc HTTP HTTP/2 Extension Frame Type), using the ALPN token defined in
Section 3.

Thus, a server could indicate in an HTTP/1.1 or HTTP/2 response header. It does so that
HTTP/QUIC was available on UDP port 443 by including the following
header in any
response sent over a non-QUIC (e.g. HTTP/2 over TLS) connection: response:

Alt-Svc: quic=":443"

In addition, hq=":443"

2.1. QUIC Version Hints

This document defines the list of "v" parameter for Alt-Svc, which is used to
provide version-negotiation hints to HTTP/QUIC clients. Syntax:

v = version
version = DQUOTE ( "c" version-string / "x" version-number ) DQUOTE
version-string = token; percent-encoded QUIC version
version-number = 1*8 HEXDIG; hex-encoded QUIC version

When multiple versions supported by are supported, the server can "v" parameter MAY be
specified by the v= parameter.
repeated multiple times in a single Alt-Svc entry. For example, if a
server supported both version 33 "Q034" and 34 version 0x00000001, it would
specify the following header:

Alt-Svc: quic=":443"; v="34,33" hq=":443";v="x1";v="cQ034"

Where multiple versions are listed, the order of the values reflects
the server's preference (with the first value being the most
preferred version).

QUIC versions are four-octet sequences with no additional constraints
on format. Versions containing octets not allowed in tokens
([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.

On receipt of this header, an Alt-Svc header indicating QUIC support, a client may MAY
attempt to establish a QUIC connection on the indicated port 443 and, if
successful, send HTTP/2 HTTP requests using the mapping described in this
document. Servers SHOULD list only versions which they support, but
MAY omit supported versions for any reason.

Connectivity problems (e.g. firewall blocking UDP) may result in QUIC
connection establishment failure, in which case the client should
gracefully fallback fall back to HTTP/2-over-TLS/TCP. HTTP/2.

3. Connection establishment

HTTP/2-over-QUIC Establishment

HTTP/QUIC connections are established as described in
[QUIC-TRANSPORT]. The QUIC During connection establishment, HTTP/QUIC support
is indicated by selecting the ALPN token "hq" in the crypto handshake MUST use TLS [QUIC-TLS].
handshake.

While connection-level options pertaining to the core QUIC protocol
are set in the initial crypto handshake [QUIC-TLS]. HTTP/2-specific handshake, HTTP-specific settings are
conveyed in the HTTP/2 SETTINGS frame. After the QUIC connection is
established, an HTTP/2 a SETTINGS frame may (Section 5.2.5) MUST be sent as the
initial frame of the QUIC headers HTTP control stream (StreamID 3, See see Section 6). As in HTTP/2, additional SETTINGS frames may be sent
mid-connection by either endpoint.

TODO: Decide whether 4).

3.1. Draft Version Identification

*RFC Editor's Note:* Please remove this section prior to acknowledge receipt
publication of SETTINGS through
empty SETTINGS frames with ACK bit set, as in HTTP/2, or rely on
transport- level acknowledgment.

Some transport-level options that HTTP/2-over-TCP specifies via the
SETTINGS frame are superseded by QUIC transport parameters in HTTP/2-
over-QUIC. Below is a listing final version of how each HTTP/2 SETTINGS parameter
is mapped:

SETTINGS_HEADER_TABLE_SIZE: Sent in HTTP/2 SETTINGS frame.

SETTINGS_ENABLE_PUSH: Sent in HTTP/2 SETTINGS frame (TBD, currently
set using QUIC "SPSH" connection option)

SETTINGS_MAX_CONCURRENT_STREAMS QUIC requires the maximum number this document.

Only implementations of
incoming streams per connection to be specified in the initial
crypto handshake, final, published RFC can identify
themselves as "hq". Until such an RFC exists, implementations MUST
NOT identify themselves using these strings.

Implementations of draft versions of the "MSPC" tag. Specifying
SETTINGS_MAX_CONCURRENT_STREAMS in protocol MUST add the HTTP/2 SETTINGS frame is an
error.

SETTINGS_INITIAL_WINDOW_SIZE: QUIC requires both stream string
"-" 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 corresponding draft number to the
HTTP/2 SETTINGS frame identifier. For
example, draft-ietf-quic-http-01 is an error.

SETTINGS_MAX_FRAME_SIZE: This setting has no equivalent in QUIC.
Specifying it in identified using the HTTP/2 SETTINGS frame is an error.

SETTINGS_MAX_HEADER_LIST_SIZE Sent in HTTP/2 SETTINGS frame.

As with HTTP/2-over-TCP, unknown SETTINGS parameters are tolerated
but ignored. SETTINGS parameters string "hq-
01".

Non-compatible experiments that are acknowledged by based on these draft versions
MUST append the receiving
peer, by sending string "-" and an empty SETTINGS frame in response with experiment name to the ACK bit
set.

4. Sending a request on an HTTP/2-over-QUIC connection

A high level overview of sending identifier.
For example, an HTTP/2 request experimental implementation based on draft-ietf-quic-
http-09 which reserves an established
QUIC connection is as follows, with further details in later sections extra stream for unsolicited transmission
of this document. A client should first encode any HTTP headers
using HPACK [RFC7541] and frame them 1980s pop music might identify itself as HTTP/2 HEADERS frames. These
are sent on StreamID 3 (see Section 6). The exact layout of "hq-09-rickroll". Note
that any label MUST conform to the
HEADERS frame is described "token" syntax defined in
Section 6.2 3.2.6 of [RFC7540]. No HTTP/2
padding is required: QUIC provides a PADDING frame for this purpose.

While HEADERS [RFC7230]. Experimenters are sent on stream 3, the mandatory stream identifier
in each HEADERS frame indicates the QUIC StreamID encouraged to
coordinate their experiments 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 stream can be terminated in one of three ways:

o the request/response is headers only, in which case a HEADERS
frame with the END_STREAM bit set ends the stream specified in the
HEADERS frame

o the request/response has headers and body but no trailing headers,
in which case the final QUIC STREAM frame will have the FIN bit
set

o the request/response has headers, body, and trailing headers, in
which case the final QUIC STREAM frame will not have the FIN bit
set, quic@ietf.org mailing list.

4. Stream Mapping and the trailing HEADERS frame will have the END_STREAM bit
set

(TODO: Describe mapping of HTTP/2 stream state machine to QUIC stream
state machine.)

5. Writing data to QUIC streams Usage

A QUIC stream provides reliable in-order delivery of bytes, within
that stream. 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/2 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.

Bytes written to

QUIC reserves Stream 1 for crypto operations (the handshake, crypto
config updates). Stream 3 must be HTTP/2 HEADERS frames (or other
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
have arrived on stream 3, then the data reserved for sending and receiving HTTP
control frames, and is buffered until the HEADERS
arrive.

6. analogous to HTTP/2's Stream Mapping 0.

When HTTP/2 HTTP headers and data are sent over QUIC, the QUIC layer handles
most of the stream management. HTTP/2 StreamIDs An HTTP request/response consumes a
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.

The lower-numbered stream is called the message control stream and
carries frames related to the request/response, including HEADERS.
All request control streams are replaced
by 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.

Pairs of streams must be utilized sequentially, with no gaps. The
data stream MUST be reserved with the QUIC StreamIDs. HTTP/2 implementation when the
message control stream is opened or reserved, and MUST be closed
after transferring the body, or else closed immediately after sending
the request headers if there is no body.

HTTP does not need to do any explicit stream
framing separate multiplexing when using QUIC -
data sent over a QUIC stream simply
consists of HTTP/2 headers or body. always maps to a particular HTTP
transaction. Requests and responses are considered complete when the
corresponding QUIC stream is streams are closed in the
corresponding appropriate direction.

Like HTTP/2, QUIC uses odd-numbered StreamIDs

4.1. Stream 3: Connection Control Stream

Since most connection-level concerns from HTTP/2 will be managed by
QUIC, the primary use of Stream 3 will be for client initiated
streams, SETTINGS and even-numbered IDs for server initiated (i.e. server
push) streams. Unlike HTTP/2 there are PRIORITY
frames. Stream 3 is exempt from connection-level flow-control.

4.2. HTTP Message Exchanges

A client sends an HTTP request on a couple new pair of reserved (or
dedicated) StreamIDs in QUIC.

6.1. Reserved Streams

StreamID 1 is reserved QUIC streams. A
server sends an HTTP response on the same streams as the request.

An HTTP message (request or response) consists of:

1. for crypto operations (the handshake, crypto
config updates), a response only, zero or more header blocks (a sequence of
HEADERS frames with End Header Block set on the last) on the
control stream containing the message headers of informational
(1xx) HTTP responses (see [RFC7230], Section 3.2 and [RFC7231],
Section 6.2),

2. one header block on the control stream containing the message
headers (see [RFC7230], Section 3.2),

3. the payload body (see [RFC7230], Section 3.3), sent on the data
stream,

4. optionally, one header block on the control stream containing the
trailer-part, if present (see [RFC7230], Section 4.1.2).

The data stream MUST NOT be used for HTTP/2 headers or half-closed immediately after the transfer of
the body. If the message does not contain a body, see
[QUIC-TRANSPORT]. StreamID 3 the corresponding
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.

Trailing header fields are carried in a header block following the
body. Such a header block is reserved for sending and receiving
HTTP/2 a sequence of HEADERS frames. Therefore frames with End
Header Block set on the last frame. Header blocks after the first client initiated data
but before the end of the stream has StreamID 5.

There are no reserved server initiated StreamIDs, so invalid. These MUST be decoded
to maintain HPACK decoder state, but the resulting output MUST be
discarded.

An HTTP request/response exchange fully consumes a pair of streams.
After sending a request, a client closes the streams for sending;
after sending a response, the first server
initiated (i.e. closes its streams for sending
and the QUIC streams are fully closed.

A server push) stream has can send a complete response prior to the client sending an ID
entire request if the response does not depend on any portion of 2, followed 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 4,
etc.

6.1.1. Stream 3: headers

HTTP/2-over-QUIC 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,
but there are no guarantees about order of delivery between streams.
To achieve in-order delivery of HEADERS frames in QUIC, they are all
sent on the reserved Stream 3. HPACK-
bearing frames contain a counter which can be used to ensure in-order
processing. Data (request/response bodies) which arrive on other data streams out of order
are buffered until the corresponding HEADERS arrive and are read out of Stream 3. arrive.

This does introduce head-of-line blocking: if the packet containing
HEADERS for stream N is lost or reordered then the HEADERS for stream N+2
N+4 cannot be processed until they it has been retransmitted successfully,
even though the HEADERS for stream N+2 N+4 may have arrived.

Trailing headers (trailers) can also

DISCUSS: Keep HPACK with HOLB? Redesign HPACK to be sent on stream 3. These are
sent as HTTP/2 HEADERS frames, but MUST have the END_STREAM bit set,
and MUST include order-
invariant? How much do we need to retain compatibility with
HTTP/2's HPACK?

4.2.2. The CONNECT Method

The pseudo-method CONNECT ([RFC7231], Section 4.3.6) is primarily
used with HTTP proxies to establish a ":final-offset" pseudo-header. Since QUIC
supports out of order delivery, receipt TLS session with an origin
server for the purposes of a HEADERS frame interacting with "https" resources. In
HTTP/1.x, CONNECT is used to convert an entire HTTP connection into a
tunnel to a remote host. In HTTP/2, the
END_STREAM bit set CONNECT method is used to
establish a tunnel over a single HTTP/2 stream to a remote host for
similar purposes.

A CONNECT request in HTTP/QUIC functions in the same manner as in
HTTP/2. The request MUST be formatted as described in [RFC7540],
Section 8.3. A CONNECT request that does not guarantee conform to these
restrictions is malformed. The message data stream MUST NOT be
closed at the end of the request.

A proxy that supports CONNECT establishes a TCP connection
([RFC0793]) to the entire request/
response body has been fully received. Therefore, server identified in the extra ":final-
offset" pseudo-header ":authority" pseudo-
header field. Once this connection is included in trailing successfully established, the
proxy sends a HEADERS frames frame containing a 2xx series status code to
indicate
the total number of body bytes sent client, as defined in [RFC7231], Section 4.3.6, on the corresponding
data message
control stream. This

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 used transmitted by the QUIC layer proxy to determine when the
full request has been TCP server; data received and therefore when it from the
TCP server is safe written to tear
down local the data stream state. The ":final-offset" pseudo header is
stripped from by the HEADERS before passing to proxy. Note that the HTTP/2 layer.

6.1.2. Stream states

The mapping of HTTP/2-over-QUIC with potential out of order delivery
size and number of HEADERS frames results in some changes TCP segments is not guaranteed to the HTTP/2 stream state
transition diagram ([RFC7540], Section 5.1}}. Specifically the
transition from "open" map predictably
to "half closed (remote)", and the transition
from "half size and number of QUIC STREAM frames.

The TCP connection can be closed (local)" by either peer. When the client
half-closes the data stream, the proxy will set the FIN bit on its
connection to "closed" takes place only when:

o the peer has explicitly ended TCP server. When the stream via either
* an HTTP/2 HEADERS frame proxy receives a packet with END_STREAM
the FIN bit set and, 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.

A TCP connection error is signaled with RST_STREAM. A proxy treats
any error in the
case of trailing headers, TCP connection, which includes receiving a TCP
segment with the :final-offset pseudo-header

* or RST bit set, as a QUIC stream frame error of type
HTTP_CONNECT_ERROR (Section 6.1). Correspondingly, a proxy MUST send
a TCP segment with the FIN RST bit set.

o and set if it detects an error with the full request
stream or response body has been received.

7. the QUIC connection.

4.3. Stream Priorities

HTTP/2-over-QUIC

HTTP/QUIC uses the HTTP/2 priority scheme described in [RFC7540]
Section 5.3. In the HTTP/2 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 HTTP/2
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
priority changes (i.e., dependency tree mutations): since operations
on the dependency tree such as reparenting a subtree are not
commutative, both sender and receiver must apply them in the same
order to ensure that both sides have a consistent view of the stream
dependency tree. HTTP/2 specifies priority assignments in PRIORITY
frames and (optionally) in HEADERS frames. To achieve in-order
delivery of HTTP/2 priority changes in HTTP/2-over-QUIC, HTTP/2 HTTP/QUIC, PRIORITY frames, in addition to HEADERS frames, frames are also sent
on
reserved the connection control stream 3. and the PRIORITY section is removed
from the HEADERS frame. The semantics of the Stream Dependency,
Weight, E flag, and (for HEADERS frames) PRIORITY flag are the same
as in
HTTP/2-over-TCP.

Since HEADERS and HTTP/2.

For consistency's sake, all 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 MUST refer to the most recent message
control stream priority information
that it has received.

ALTERNATIVE DESIGN: if the core QUIC protocol implements priorities,
then this document should map the HTTP/2 priorities scheme to that
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. dependent request, not the data stream.

4.4. Flow Control

QUIC provides stream and connection level flow control, similar in
principle to HTTP/2's flow control but with some implementation
differences. As flow control is handled by QUIC, the HTTP/2 HTTP mapping
need not concern itself with maintaining flow control state, or how/
when to send flow control frames to the peer. state. The HTTP/2
HTTP mapping
must not 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 frames at the flow control windows based on usage. See
[QUIC-TRANSPORT] for more details.

9. HTTP level.

4.5. Server Push

HTTP/2-over-QUIC

HTTP/QUIC supports HTTP/2 server push. push as described in [RFC7540]. During
connection establishment, the client indicates whether or it is willing
to receive server pushes via the SETTINGS_ENABLE_PUSH setting in the
HTTP/2
SETTINGS frame (see Section 3), which defaults to 1 (true).

As with server push for HTTP/2-over-TCP, HTTP/2, the server initiates a server push by
sending an HTTP/2 a PUSH_PROMISE frame containing the StreamID of the stream to
be pushed, as well as request header fields attributed to the
request. The PUSH_PROMISE frame is sent on stream
3, to ensure proper ordering with respect to other HEADERS and non-
data frames. Within the PUSH_PROMISE frame, the StreamID in the
common HTTP/2 frame header indicates the associated (client-
initiated) control stream for of the new push stream,
associated (client-initiated) request, while the Promised Stream ID
field specifies the StreamID Stream ID of the new push stream. control stream for the server-
initiated request.

The server push response is conveyed in the same way as a non-server-
push response, with response headers and (if present) trailers
carried by HTTP/2 HEADERS frames sent on reserved stream 3, the control stream, and response
body (if any) sent via QUIC stream the corresponding data stream.

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
specified in number. Because frames do not block
multiplexing (QUIC's multiplexing occurs below this layer), the corresponding PUSH_PROMISE frame.

10. Error Codes

The HTTP/2 error codes defined in Section 7 of [RFC7540] map to QUIC
error codes as follows:

NO_ERROR (0x0): Maps to QUIC_NO_ERROR
PROTOCOL_ERROR (0x1): No single mapping?

INTERNAL_ERROR (0x2) QUIC_INTERNAL_ERROR? (not currently defined in
core protocol spec)

FLOW_CONTROL_ERROR (0x3): QUIC_FLOW_CONTROL_RECEIVED_TOO_MUCH_DATA?
(not currently defined in core protocol spec)

SETTINGS_TIMEOUT (0x4): (depends on whether we support SETTINGS
acks)

STREAM_CLOSED (0x5): QUIC_STREAM_DATA_AFTER_TERMINATION

FRAME_SIZE_ERROR (0x6) QUIC_INVALID_FRAME_DATA

REFUSED_STREAM (0x7): ?

CANCEL (0x8): ?

COMPRESSION_ERROR (0x9): QUIC_DECOMPRESSION_FAILURE (not currently
defined in core spec)

CONNECT_ERROR (0xa): ? (depends whether we decide to
support
CONNECT)

ENHANCE_YOUR_CALM (0xb): ?

INADEQUATE_SECURITY (0xc): QUIC_HANDSHAKE_FAILED,
QUIC_CRYPTO_NO_SUPPORT

HTTP_1_1_REQUIRED (0xd): ?

TODO: fill in missing error code mappings.

11. 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 HTTP/2 frames 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 cases, the HTTP/2 HTTP mapping need not re-
implement re-implement them.
As a result result, some HTTP/2 frame types are not required when using QUIC, as they either are directly implemented 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
layer, or their functionality 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 provided via other means. 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
section 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 document describes these cases.

11.1. GOAWAY 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 its own GOAWAY frame, 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 implementations may 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 expose 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 GOAWAY peer
uses SETTINGS to the application. advertise a set of supported values. The semantics 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 sending 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 GOAWAY 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 QUIC a SETTINGS frame replaces any existing value for
that parameter. Parameters are identical processed in the order in which they
appear, and a receiver of a SETTINGS frame does not need to HTTP/2: 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 sending receives an SETTINGS frame whose stream identifier
field is anything other than 0x0, the endpoint MUST respond with a
GOAWAY will continue processing open streams,
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 will not accept
newly created streams.

QUIC's GOAWAY 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 described 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 detail the initial
crypto handshake, using the "MSPC" tag. Specifying
SETTINGS_MAX_CONCURRENT_STREAMS in the [QUIC-TRANSPORT].

11.2. PING 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 its own PING frame, which no equivalent in QUIC.
Specifying it in the SETTINGS frame is currently exposed 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
application. QUIC clients send periodic PINGs 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 servers 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 there
are no currently active data 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 connection.

QUIC's 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 described 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 detail the "idle" state

Highest Remote Stream (32 bits): The highest peer-initiated Stream
ID which is not in the [QUIC-TRANSPORT].

11.3. PADDING "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

There is carries no HTTP/2 padding in this mapping; padding
payload, and is instead
provided at 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 layer 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 including HTTP for use in
QUIC PADDING frames 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
packet payload. 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 HTTP/2 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 QUIC mapping HTTP/QUIC. The peer should treat any HTTP/2
level padding as retry over HTTP/2.

HTTP_MALFORMED_HEADERS (0x09): A HEADERS frame has been received
with an error, to avoid any possibility of inconsistent
flow 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 states between endpoints (e.g. client sends stream.

6.2. Mapping HTTP/2
padding, counts it against Error Codes

The HTTP/2 error codes defined in Section 7 of [RFC7540] map to QUIC
error codes as follows:

NO_ERROR (0x0): QUIC_NO_ERROR

PROTOCOL_ERROR (0x1): No single mapping. See new HTTP_MALFORMED_*
error codes defined in Section 6.1.

INTERNAL_ERROR (0x2) HTTP_INTERNAL_ERROR in Section 6.1.

FLOW_CONTROL_ERROR (0x3): Not applicable, since QUIC handles flow control, server ignores).

12.
control. Would provoke a QUIC_FLOW_CONTROL_RECEIVED_TOO_MUCH_DATA
from the QUIC layer.

SETTINGS_TIMEOUT (0x4): HTTP_SETTINGS_TIMEOUT in Section 6.1.

STREAM_CLOSED (0x5): Not applicable, since QUIC handles stream
management. Would provoke a QUIC_STREAM_DATA_AFTER_TERMINATION
from the QUIC layer.

FRAME_SIZE_ERROR (0x6) No single mapping. See new error codes
defined in Section 6.1.

REFUSED_STREAM (0x7): Not applicable, since QUIC handles stream
management. Would provoke a QUIC_TOO_MANY_OPEN_STREAMS from the
QUIC layer.

CANCEL (0x8): HTTP_REQUEST_CANCELLED in Section 6.1.

COMPRESSION_ERROR (0x9): HTTP_HPACK_DECOMPRESSION_FAILED in
Section 6.1.

CONNECT_ERROR (0xa): HTTP_CONNECT_ERROR in Section 6.1.

ENHANCE_YOUR_CALM (0xb): HTTP_EXCESSIVE_LOAD in Section 6.1.

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.

7. Security Considerations

The security considerations of HTTP over QUIC should be comparable to
those of HTTP/2.

13.

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.

8. IANA Considerations

8.1. Registration of HTTP/QUIC Identification String

This document has no IANA actions. Yet.

14. creates a new registration for the identification of
HTTP/QUIC in the "Application Layer Protocol Negotiation (ALPN)
Protocol IDs" registry established in [RFC7301].

The "hq" string identifies HTTP/QUIC:

Protocol: HTTP over QUIC

Identification Sequence: 0x68 0x71 ("hq")

Specification: This document

8.2. Registration of Version Hint Alt-Svc Parameter

This document creates a new registration for version-negotiation
hints in the "Hypertext Transfer Protocol (HTTP) Alt-Svc Parameter"
registry established in [RFC7838].

Parameter: "v"

Specification: This document, Section 2.1

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:

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]
Thomson, M., Ed. and S. Turner, Ed, Ed., "Using Transport
Layer Security (TLS) to Secure QUIC", November 2016. QUIC".

[QUIC-TRANSPORT]
Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
Multiplexed and Secure Transport", November 2016. 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
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<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
Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
DOI 10.17487/RFC7540, May 2015,
<http://www.rfc-editor.org/info/rfc7540>.

[RFC7541] Peon, R. and H. Ruellan, "HPACK: Header Compression for
HTTP/2", RFC 7541, DOI 10.17487/RFC7541, May 2015,
<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

The original authors of this specification were Robbie Shade and Mike
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

Mike Bishop (editor)
Microsoft

Email: Mike.Bishop@microsoft.com Michael.Bishop@microsoft.com