Using Datagrams with HTTP
draft-ietf-masque-h3-datagram-06
The information below is for an old version of the document.
| Document | Type | Active Internet-Draft (masque WG) | |
|---|---|---|---|
| Authors | David Schinazi , Lucas Pardue | ||
| Last updated | 2022-03-21 (Latest revision 2022-03-04) | ||
| Replaces | draft-schinazi-masque-h3-datagram | ||
| Stream | Internet Engineering Task Force (IETF) | ||
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draft-ietf-masque-h3-datagram-06
MASQUE D. Schinazi
Internet-Draft Google LLC
Intended status: Standards Track L. Pardue
Expires: 5 September 2022 Cloudflare
4 March 2022
Using Datagrams with HTTP
draft-ietf-masque-h3-datagram-06
Abstract
The QUIC DATAGRAM extension provides application protocols running
over QUIC with a mechanism to send unreliable data while leveraging
the security and congestion-control properties of QUIC. However,
QUIC DATAGRAM frames do not provide a means to demultiplex
application contexts. This document describes how to use QUIC
DATAGRAM frames with HTTP/3 by association with HTTP requests.
Additionally, this document defines the Capsule Protocol that can
convey datagrams over prior versions of HTTP.
Discussion Venues
This note is to be removed before publishing as an RFC.
Discussion of this document takes place on the MASQUE WG mailing list
(masque@ietf.org), which is archived at
https://mailarchive.ietf.org/arch/browse/masque/.
Source for this draft and an issue tracker can be found at
https://github.com/ietf-wg-masque/draft-ietf-masque-h3-datagram.
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 https://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 5 September 2022.
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Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Conventions and Definitions . . . . . . . . . . . . . . . 3
2. Multiplexing . . . . . . . . . . . . . . . . . . . . . . . . 3
3. HTTP/3 Datagram Format . . . . . . . . . . . . . . . . . . . 4
3.1. The H3_DATAGRAM HTTP/3 SETTINGS Parameter . . . . . . . . 5
3.1.1. Note About Draft Versions . . . . . . . . . . . . . . 6
4. Capsules . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.1. Capsule Protocol . . . . . . . . . . . . . . . . . . . . 7
4.2. Error Handling . . . . . . . . . . . . . . . . . . . . . 8
4.3. The Capsule-Protocol Header Field . . . . . . . . . . . . 8
4.4. The DATAGRAM Capsule . . . . . . . . . . . . . . . . . . 9
5. Prioritization . . . . . . . . . . . . . . . . . . . . . . . 10
6. Security Considerations . . . . . . . . . . . . . . . . . . . 11
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
7.1. HTTP/3 SETTINGS Parameter . . . . . . . . . . . . . . . . 11
7.2. HTTP/3 Error Code . . . . . . . . . . . . . . . . . . . . 11
7.3. HTTP Header Field Name . . . . . . . . . . . . . . . . . 12
7.4. Capsule Types . . . . . . . . . . . . . . . . . . . . . . 12
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
8.1. Normative References . . . . . . . . . . . . . . . . . . 13
8.2. Informative References . . . . . . . . . . . . . . . . . 14
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 14
A.1. CONNECT-UDP . . . . . . . . . . . . . . . . . . . . . . . 14
A.2. WebTransport . . . . . . . . . . . . . . . . . . . . . . 15
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
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1. Introduction
The QUIC DATAGRAM extension [DGRAM] provides application protocols
running over QUIC [QUIC] with a mechanism to send unreliable data
while leveraging the security and congestion-control properties of
QUIC. However, QUIC DATAGRAM frames do not provide a means to
demultiplex application contexts. This document describes how to use
QUIC DATAGRAM frames with HTTP/3 [H3] by association with HTTP
requests. Additionally, this document defines the Capsule Protocol
that can convey datagrams over prior versions of HTTP.
This document is structured as follows:
* Section 2 presents core concepts for multiplexing across HTTP
versions.
* Section 3 defines how QUIC DATAGRAM frames are used with HTTP/3.
- Section 3.1 defines an HTTP/3 setting that endpoints can use to
advertise support of the frame.
* Section 4 introduces the Capsule Protocol and the "data stream"
concept. Data streams are initiated using special-purpose HTTP
requests, after which Capsules, an end-to-end message, can be
sent.
- Section 4.4 defines Datagram Capsule types, along with guidance
for specifying new capsule types.
1.1. Conventions and Definitions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Multiplexing
All HTTP Datagrams are associated with an HTTP request.
When running over HTTP/3, multiple exchanges of datagrams need the
ability to coexist on a given QUIC connection. To allow this, the
QUIC DATAGRAM frame payload starts with an encoded stream identifier
that associates the datagram with a request stream.
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When running over HTTP/2, demultiplexing is provided by the HTTP/2
framing layer. When running over HTTP/1, requests are strictly
serialized in the connection, therefore demultiplexing is not needed.
3. HTTP/3 Datagram Format
When used with HTTP/3, the Datagram Data field of QUIC DATAGRAM
frames uses the following format (using the notation from the
"Notational Conventions" section of [QUIC]):
HTTP/3 Datagram {
Quarter Stream ID (i),
HTTP Datagram Payload (..),
}
Figure 1: HTTP/3 DATAGRAM Format
Quarter Stream ID: A variable-length integer that contains the value
of the client-initiated bidirectional stream that this datagram is
associated with, divided by four (the division by four stems from
the fact that HTTP requests are sent on client-initiated
bidirectional streams, and those have stream IDs that are
divisible by four). The largest legal QUIC stream ID value is
2^62-1, so the largest legal value of Quarter Stream ID is 2^60-1.
Receipt of a frame that includes a larger value MUST be treated as
an HTTP/3 connection error of type H3_DATAGRAM_ERROR.
HTTP Datagram Payload: The payload of the datagram, whose semantics
are defined by individual applications. Note that this field can
be empty.
Receipt of a QUIC DATAGRAM frame whose payload is too short to allow
parsing the Quarter Stream ID field MUST be treated as an HTTP/3
connection error of type H3_DATAGRAM_ERROR.
Endpoints MUST NOT send HTTP/3 datagrams unless the corresponding
stream's send side is open. On a given endpoint, once the receive
side of a stream is closed, incoming datagrams for this stream are no
longer expected so the endpoint can release related state. Endpoints
MAY keep state for a short time to account for reordering. Once the
state is released, the endpoint MUST silently drop received
associated datagrams.
If an HTTP/3 datagram is received and its Quarter Stream ID maps to a
stream that has not yet been created, the receiver SHALL either drop
that datagram silently or buffer it temporarily (on the order of a
round trip) while awaiting the creation of the corresponding stream.
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If an HTTP/3 datagram is received and its Quarter Stream ID maps to a
stream that cannot be created due to client-initiated bidirectional
stream limits, it SHOULD be treated as an HTTP/3 connection error of
type H3_ID_ERROR. Generating an error is not mandatory in this case
because HTTP/3 implementations might have practical barriers to
determining the active stream concurrency limit that is applied by
the QUIC layer.
HTTP/3 datagrams MUST only be sent with an association to a stream
that supports semantics for HTTP Datagrams. For example, existing
HTTP methods GET and POST do not define semantics for associated HTTP
Datagrams; therefore, HTTP/3 datagrams cannot be sent associated with
GET or POST request streams. If an endpoint receives an HTTP/3
datagram associated with a method that has no known semantics for
HTTP Datagrams, it MUST abort the corresponding stream with
H3_DATAGRAM_ERROR. Future extensions MAY remove these requirements
if they define semantics for such HTTP Datagrams and negotiate mutual
support.
3.1. The H3_DATAGRAM HTTP/3 SETTINGS Parameter
Implementations of HTTP/3 that support HTTP Datagrams can indicate
that to their peer by sending the H3_DATAGRAM SETTINGS parameter with
a value of 1. The value of the H3_DATAGRAM SETTINGS parameter MUST
be either 0 or 1. A value of 0 indicates that HTTP Datagrams are not
supported. An endpoint that receives the H3_DATAGRAM SETTINGS
parameter with a value that is neither 0 or 1 MUST terminate the
connection with error H3_SETTINGS_ERROR.
Endpoints MUST NOT send QUIC DATAGRAM frames until they have both
sent and received the H3_DATAGRAM SETTINGS parameter with a value of
1.
When clients use 0-RTT, they MAY store the value of the server's
H3_DATAGRAM SETTINGS parameter. Doing so allows the client to send
QUIC DATAGRAM frames in 0-RTT packets. When servers decide to accept
0-RTT data, they MUST send a H3_DATAGRAM SETTINGS parameter greater
than or equal to the value they sent to the client in the connection
where they sent them the NewSessionTicket message. If a client
stores the value of the H3_DATAGRAM SETTINGS parameter with their
0-RTT state, they MUST validate that the new value of the H3_DATAGRAM
SETTINGS parameter sent by the server in the handshake is greater
than or equal to the stored value; if not, the client MUST terminate
the connection with error H3_SETTINGS_ERROR. In all cases, the
maximum permitted value of the H3_DATAGRAM SETTINGS parameter is 1.
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It is RECOMMENDED that implementations that support receiving HTTP
Datagrams using QUIC always send the H3_DATAGRAM SETTINGS parameter
with a value of 1, even if the application does not intend to use
HTTP Datagrams. This helps to avoid "sticking out"; see Section 6.
3.1.1. Note About Draft Versions
[[RFC editor: please remove this section before publication.]]
Some revisions of this draft specification use a different value (the
Identifier field of a Setting in the HTTP/3 SETTINGS frame) for the
H3_DATAGRAM Settings Parameter. This allows new draft revisions to
make incompatible changes. Multiple draft versions MAY be supported
by either endpoint in a connection. Such endpoints MUST send
multiple values for H3_DATAGRAM. Once an endpoint has sent and
received SETTINGS, it MUST compute the intersection of the values it
has sent and received, and then it MUST select and use the most
recent draft version from the intersection set. This ensures that
both endpoints negotiate the same draft version.
4. Capsules
This specification introduces the Capsule Protocol. The Capsule
Protocol is a sequence of type-length-value tuples that new HTTP
Upgrade Tokens (see Section 16.7 of [HTTP]) can choose to use. It
allows endpoints to reliably communicate request-related information
end-to-end on HTTP request streams, even in the presence of HTTP
intermediaries. The Capsule Protocol can be used to exchange HTTP
Datagrams when HTTP is running over a transport that does not support
the QUIC DATAGRAM frame.
This specification defines the "data stream" of an HTTP request as
the bidirectional stream of bytes that follow the headers in both
directions. In HTTP/1.x, the data stream consists of all bytes on
the connection that follow the blank line that concludes either the
request header section, or the 2xx (Successful) response header
section. (Note that only a single HTTP request starting the capsule
protocol can be sent on HTTP/1.x connections.) In HTTP/2 and HTTP/3,
the data stream of a given HTTP request consists of all bytes sent in
DATA frames with the corresponding stream ID. The concept of a data
stream is particularly relevant for methods such as CONNECT where
there is no HTTP message content after the headers.
Note that use of the Capsule Protocol is not required to use HTTP
Datagrams. If a new HTTP Upgrade Token is only defined over
transports that support QUIC DATAGRAM frames, they might not need a
stream encoding. Additionally, definitions of new HTTP Upgrade
Tokens can use HTTP Datagrams with their own data stream protocol.
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However, new HTTP Upgrade Tokens that wish to use HTTP Datagrams
SHOULD use the Capsule Protocol unless they have a good reason not
to.
4.1. Capsule Protocol
Definitions of new HTTP Upgrade Tokens can state that their data
stream uses the Capsule Protocol. If they do so, that means that the
contents of their data stream uses the following format (using the
notation from the "Notational Conventions" section of [QUIC]):
Capsule Protocol {
Capsule (..) ...,
}
Figure 2: Capsule Protocol Stream Format
Capsule {
Capsule Type (i),
Capsule Length (i),
Capsule Value (..),
}
Figure 3: Capsule Format
Capsule Type: A variable-length integer indicating the Type of the
capsule. Endpoints that receive a capsule with an unknown Capsule
Type MUST silently skip over that capsule.
Capsule Length: The length of the Capsule Value field following this
field, encoded as a variable-length integer. Note that this field
can have a value of zero.
Capsule Value: The payload of this capsule. Its semantics are
determined by the value of the Capsule Type field.
Because new protocols or extensions may involve defining new capsule
types, intermediaries that wish to allow for future extensibility
SHOULD forward capsules unmodified. One exception to this rule is
the DATAGRAM capsule; see Section 4.4. An intermediary can identify
the use of the capsule protocol either through the presence of the
Capsule-Protocol header field (Section 4.3) or by understanding the
chosen HTTP Upgrade token. An intermediary that identifies the use
of the capsule protocol MAY convert between DATAGRAM capsules and
QUIC DATAGRAM frames when forwarding. Definitions of new Capsule
Types MAY specify optional custom intermediary processing.
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Endpoints which receive a Capsule with an unknown Capsule Type MUST
silently drop that Capsule.
By virtue of the definition of the data stream, the Capsule Protocol
is not in use on responses unless the response includes a 2xx
(Successful) status code.
The Capsule Protocol MUST NOT be used with messages that contain
Content-Length, Content-Type, or Transfer-Encoding header fields.
Additionally, HTTP status codes 204 (No Content), 205 (Reset
Content), and 206 (Partial Content) MUST NOT be sent on responses
that use the Capsule Protocol.
4.2. Error Handling
When an error occurs processing the capsule protocol, the receiver
MUST treat the message as malformed or incomplete, according to the
underlying transport protocol. For HTTP/3, the handling of malformed
messages is described in Section 4.1.3 of [H3]. For HTTP/2, the
handling of malformed messages is described in Section 8.1.1 of [H2].
For HTTP/1.1, the handling of incomplete messages is described in
Section 8 of [H1].
Each capsule's payload MUST contain exactly the fields identified in
its description. A capsule payload that contains additional bytes
after the identified fields or a capsule payload that terminates
before the end of the identified fields MUST be treated as a
malformed or incomplete message. In particular, redundant length
encodings MUST be verified to be self-consistent.
When a stream carrying capsules terminates cleanly, if the last
capsule on the stream was truncated, this MUST be treated as a
malformed or incomplete message.
4.3. The Capsule-Protocol Header Field
This document defines the "Capsule-Protocol" header field. It is an
Item Structured Field, see Section 3.3 of [STRUCT-FIELD]; its value
MUST be a Boolean. Its ABNF is:
Capsule-Protocol = sf-item
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Endpoints indicate that the Capsule Protocol is in use on the data
stream by sending the Capsule-Protocol header field with a value of
?1. A Capsule-Protocol header field with a value of ?0 has the same
semantics as when the header is not present. Intermediaries MAY use
this header field to allow processing of HTTP Datagrams for unknown
HTTP Upgrade Tokens; note that this is only possible for HTTP Upgrade
or Extended CONNECT.
The Capsule-Protocol header field MUST NOT be sent multiple times on
a message. The Capsule-Protocol header field MUST NOT be used on
HTTP responses with a status code different from 2xx (Successful).
This specification does not define any parameters for the Capsule-
Protocol header field value, but future documents MAY define
parameters. Receivers MUST ignore unknown parameters.
Definitions of new HTTP Upgrade Tokens that use the Capsule Protocol
MAY use the Capsule-Protocol header field to simplify intermediary
processing.
4.4. The DATAGRAM Capsule
This document defines the DATAGRAM capsule type (see Section 7.4 for
the value of the capsule type). This capsule allows an endpoint to
send an HTTP Datagram on a stream using the Capsule Protocol. This
is particularly useful when HTTP is running over a transport that
does not support the QUIC DATAGRAM frame.
Datagram Capsule {
Type (i) = DATAGRAM,
Length (i),
HTTP Datagram Payload (..),
}
Figure 4: DATAGRAM Capsule Format
HTTP Datagram Payload: The payload of the datagram, whose semantics
are defined by individual applications. Note that this field can
be empty.
Datagrams sent using the DATAGRAM capsule have the same semantics as
datagrams sent in QUIC DATAGRAM frames. In particular, the
restrictions on when it is allowed to send an HTTP Datagram and how
to process them from Section 3 also apply to HTTP Datagrams sent and
received using the DATAGRAM capsule.
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An intermediary can reencode HTTP Datagrams as it forwards them. In
other words, an intermediary MAY send a DATAGRAM capsule to forward
an HTTP Datagram which was received in a QUIC DATAGRAM frame, and
vice versa.
Note that while DATAGRAM capsules that are sent on a stream are
reliably delivered in order, intermediaries can reencode DATAGRAM
capsules into QUIC DATAGRAM frames when forwarding messages, which
could result in loss or reordering.
If an intermediary receives an HTTP Datagram in a QUIC DATAGRAM frame
and is forwarding it on a connection that supports QUIC DATAGRAM
frames, the intermediary SHOULD NOT convert that HTTP Datagram to a
DATAGRAM capsule. If the HTTP Datagram is too large to fit in a
DATAGRAM frame (for example because the path MTU of that QUIC
connection is too low or if the maximum UDP payload size advertised
on that connection is too low), the intermediary SHOULD drop the HTTP
Datagram instead of converting it to a DATAGRAM capsule. This
preserves the end-to-end unreliability characteristic that methods
such as Datagram Packetization Layer Path MTU Discovery (DPLPMTUD)
depend on [DPLPMTUD]. An intermediary that converts QUIC DATAGRAM
frames to DATAGRAM capsules allows HTTP Datagrams to be arbitrarily
large without suffering any loss; this can misrepresent the true path
properties, defeating methods such as DPLPMTUD.
While DATAGRAM capsules can theoretically carry a payload of length
2^62-1, most applications will have their own limits on what datagran
payload sizes are practical. Implementations SHOULD take those
limits into account when parsing DATAGRAM capsules: if an incoming
DATAGRAM capsule has a length that is known to be so large as to not
be usable, the implementation SHOULD discard the capsule without
buffering its contents into memory.
5. Prioritization
Data streams (see Section 4.1) can be prioritized using any means
suited to stream or request prioritization. For example, see
Section 11 of [PRIORITY].
Prioritization of HTTP/3 datagrams is not defined in this document.
Future extensions MAY define how to prioritize datagrams, and MAY
define signaling to allow endpoints to communicate their
prioritization preferences.
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6. Security Considerations
Since transmitting HTTP Datagrams using QUIC DATAGRAM frames requires
sending an HTTP/3 Settings parameter, it "sticks out". In other
words, probing clients can learn whether a server supports HTTP
Datagrams over QUIC DATAGRAM frames. As some servers might wish to
obfuscate the fact that they offer application services that use HTTP
datagrams, it's best for all implementations that support this
feature to always send this Settings parameter, see Section 3.1.
Since use of the Capsule Protocol is restricted to new HTTP Upgrade
Tokens, it is not accessible from Web Platform APIs (such as those
commonly accessed via JavaScript in web browsers).
7. IANA Considerations
7.1. HTTP/3 SETTINGS Parameter
This document will request IANA to register the following entry in
the "HTTP/3 Settings" registry:
Value: 0xffd277 (note that this will switch to a lower value before
publication)
Setting Name: H3_DATAGRAM
Default: 0
Status: provisional (permanent if this document is approved)
Specification: This Document
Change Controller: IETF
Contact: HTTP_WG; HTTP working group; ietf-http-wg@w3.org
7.2. HTTP/3 Error Code
This document will request IANA to register the following entry in
the "HTTP/3 Error Codes" registry:
Value: 0x4A1268 (note that this will switch to a lower value before
publication)
Name: H3_DATAGRAM_ERROR
Description: Datagram or capsule protocol parse error
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Status: provisional (permanent if this document is approved)
Specification: This Document
Change Controller: IETF
Contact: HTTP_WG; HTTP working group; ietf-http-wg@w3.org
7.3. HTTP Header Field Name
This document will request IANA to register the following entry in
the "HTTP Field Name" registry:
Field Name: Capsule-Protocol
Template: None
Status: provisional (permanent if this document is approved)
Reference: This document
Comments: None
7.4. Capsule Types
This document establishes a registry for HTTP capsule type codes.
The "HTTP Capsule Types" registry governs a 62-bit space.
Registrations in this registry MUST include the following fields:
Type: A name or label for the capsule type.
Value: The value of the Capsule Type field (see Section 4.1) is a
62-bit integer.
Reference: An optional reference to a specification for the type.
This field MAY be empty.
Registrations follow the "First Come First Served" policy (see
Section 4.4 of [IANA-POLICY]) where two registrations MUST NOT have
the same Type.
This registry initially contains the following entry:
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+==============+==========+===============+
| Capsule Type | Value | Specification |
+==============+==========+===============+
| DATAGRAM | 0xff37a5 | This Document |
+--------------+----------+---------------+
Table 1: Initial Capsule Types Registry
Capsule types with a value of the form 41 * N + 23 for integer values
of N are reserved to exercise the requirement that unknown capsule
types be ignored. These capsules have no semantics and can carry
arbitrary values. These values MUST NOT be assigned by IANA and MUST
NOT appear in the listing of assigned values.
8. References
8.1. Normative References
[DGRAM] Pauly, T., Kinnear, E., and D. Schinazi, "An Unreliable
Datagram Extension to QUIC", Work in Progress, Internet-
Draft, draft-ietf-quic-datagram-10, 4 February 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-quic-
datagram-10>.
[H1] Fielding, R. T., Nottingham, M., and J. Reschke,
"HTTP/1.1", Work in Progress, Internet-Draft, draft-ietf-
httpbis-messaging-19, 12 September 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-
messaging-19>.
[H2] Thomson, M. and C. Benfield, "HTTP/2", Work in Progress,
Internet-Draft, draft-ietf-httpbis-http2bis-07, 24 January
2022, <https://datatracker.ietf.org/doc/html/draft-ietf-
httpbis-http2bis-07>.
[H3] Bishop, M., "Hypertext Transfer Protocol Version 3
(HTTP/3)", Work in Progress, Internet-Draft, draft-ietf-
quic-http-34, 2 February 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-quic-
http-34>.
[HTTP] Fielding, R. T., Nottingham, M., and J. Reschke, "HTTP
Semantics", Work in Progress, Internet-Draft, draft-ietf-
httpbis-semantics-19, 12 September 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-
semantics-19>.
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[IANA-POLICY]
Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/rfc/rfc8126>.
[QUIC] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
Multiplexed and Secure Transport", RFC 9000,
DOI 10.17487/RFC9000, May 2021,
<https://www.rfc-editor.org/rfc/rfc9000>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/rfc/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
[STRUCT-FIELD]
Nottingham, M. and P-H. Kamp, "Structured Field Values for
HTTP", RFC 8941, DOI 10.17487/RFC8941, February 2021,
<https://www.rfc-editor.org/rfc/rfc8941>.
8.2. Informative References
[DPLPMTUD] Fairhurst, G., Jones, T., Tüxen, M., Rüngeler, I., and T.
Völker, "Packetization Layer Path MTU Discovery for
Datagram Transports", RFC 8899, DOI 10.17487/RFC8899,
September 2020, <https://www.rfc-editor.org/rfc/rfc8899>.
[PRIORITY] Oku, K. and L. Pardue, "Extensible Prioritization Scheme
for HTTP", Work in Progress, Internet-Draft, draft-ietf-
httpbis-priority-12, 17 January 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-
priority-12>.
Appendix A. Examples
[[RFC editor: please remove this appendix before publication.]]
A.1. CONNECT-UDP
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Client Server
STREAM(44): HEADERS -------->
:method = CONNECT
:protocol = connect-udp
:scheme = https
:path = /target.example.org/443/
:authority = proxy.example.org:443
capsule-protocol = ?1
DATAGRAM -------->
Quarter Stream ID = 11
Payload = Encapsulated UDP Payload
<-------- STREAM(44): HEADERS
:status = 200
capsule-protocol = ?1
/* Wait for target server to respond to UDP packet. */
<-------- DATAGRAM
Quarter Stream ID = 11
Payload = Encapsulated UDP Payload
A.2. WebTransport
Client Server
STREAM(44): HEADERS -------->
:method = CONNECT
:scheme = https
:protocol = webtransport
:path = /hello
:authority = webtransport.example.org:443
origin = https://www.example.org:443
<-------- STREAM(44): HEADERS
:status = 200
/* Both endpoints can now send WebTransport datagrams. */
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Acknowledgments
Portions of this document were previously part of the QUIC DATAGRAM
frame definition itself, the authors would like to acknowledge the
authors of that document and the members of the IETF MASQUE working
group for their suggestions. Additionally, the authors would like to
thank Martin Thomson for suggesting the use of an HTTP/3 SETTINGS
parameter. Furthermore, the authors would like to thank Ben Schwartz
for writing the first proposal that used two layers of indirection.
The final design in this document came out of the HTTP Datagrams
Design Team, whose members were Alan Frindell, Alex Chernyakhovsky,
Ben Schwartz, Eric Rescorla, Marcus Ihlar, Martin Thomson, Mike
Bishop, Tommy Pauly, Victor Vasiliev, and the authors of this
document.
Authors' Addresses
David Schinazi
Google LLC
1600 Amphitheatre Parkway
Mountain View, California 94043,
United States of America
Email: dschinazi.ietf@gmail.com
Lucas Pardue
Cloudflare
Email: lucaspardue.24.7@gmail.com
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