draft-ietf-masque-h3-datagram-03.txt   draft-ietf-masque-h3-datagram-04.txt 
MASQUE D. Schinazi MASQUE D. Schinazi
Internet-Draft Google LLC Internet-Draft Google LLC
Intended status: Standards Track L. Pardue Intended status: Standards Track L. Pardue
Expires: 13 January 2022 Cloudflare Expires: 10 April 2022 Cloudflare
12 July 2021 7 October 2021
Using Datagrams with HTTP Using Datagrams with HTTP
draft-ietf-masque-h3-datagram-03 draft-ietf-masque-h3-datagram-04
Abstract Abstract
The QUIC DATAGRAM extension provides application protocols running The QUIC DATAGRAM extension provides application protocols running
over QUIC with a mechanism to send unreliable data while leveraging over QUIC with a mechanism to send unreliable data while leveraging
the security and congestion-control properties of QUIC. However, the security and congestion-control properties of QUIC. However,
QUIC DATAGRAM frames do not provide a means to demultiplex QUIC DATAGRAM frames do not provide a means to demultiplex
application contexts. This document describes how to use QUIC application contexts. This document describes how to use QUIC
DATAGRAM frames when the application protocol running over QUIC is DATAGRAM frames when the application protocol running over QUIC is
HTTP/3. It associates datagrams with client-initiated bidirectional HTTP/3. It associates datagrams with client-initiated bidirectional
skipping to change at page 2, line 4 skipping to change at page 2, line 4
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This Internet-Draft will expire on 13 January 2022. This Internet-Draft will expire on 10 April 2022.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Conventions and Definitions . . . . . . . . . . . . . . . 3 1.1. Conventions and Definitions . . . . . . . . . . . . . . . 4
2. Multiplexing . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Multiplexing . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Datagram Contexts . . . . . . . . . . . . . . . . . . . . 4 2.1. Datagram Contexts . . . . . . . . . . . . . . . . . . . . 4
2.2. Context ID Allocation . . . . . . . . . . . . . . . . . . 4 2.2. Datagram Formats . . . . . . . . . . . . . . . . . . . . 5
3. HTTP/3 DATAGRAM Format . . . . . . . . . . . . . . . . . . . 4 2.3. Context ID Allocation . . . . . . . . . . . . . . . . . . 5
4. CAPSULE HTTP/3 Frame Definition . . . . . . . . . . . . . . . 6 3. HTTP/3 DATAGRAM Format . . . . . . . . . . . . . . . . . . . 6
4.1. The REGISTER_DATAGRAM_CONTEXT Capsule . . . . . . . . . . 7 4. Capsules . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.2. The REGISTER_DATAGRAM_NO_CONTEXT Capsule . . . . . . . . 9 4.1. Capsule Protocol . . . . . . . . . . . . . . . . . . . . 8
4.3. The CLOSE_DATAGRAM_CONTEXT Capsule . . . . . . . . . . . 10 4.2. Requirements . . . . . . . . . . . . . . . . . . . . . . 9
4.4. The DATAGRAM Capsule . . . . . . . . . . . . . . . . . . 11 4.3. Intermediary Processing . . . . . . . . . . . . . . . . . 9
5. Context Extensibility . . . . . . . . . . . . . . . . . . . . 12 4.4. Capsule Types . . . . . . . . . . . . . . . . . . . . . . 10
5.1. The CLOSE_CODE Context Extension Type . . . . . . . . . . 13 4.4.1. The REGISTER_DATAGRAM_CONTEXT Capsule . . . . . . . . 10
5.2. The DETAILS Context Extension Type . . . . . . . . . . . 13 4.4.2. The REGISTER_DATAGRAM_NO_CONTEXT Capsule . . . . . . 11
6. The H3_DATAGRAM HTTP/3 SETTINGS Parameter . . . . . . . . . . 13 4.4.3. The CLOSE_DATAGRAM_CONTEXT Capsule . . . . . . . . . 12
7. Prioritization . . . . . . . . . . . . . . . . . . . . . . . 14 4.4.4. The DATAGRAM Capsule . . . . . . . . . . . . . . . . 14
8. HTTP/1.x and HTTP/2 Support . . . . . . . . . . . . . . . . . 14 5. The H3_DATAGRAM HTTP/3 SETTINGS Parameter . . . . . . . . . . 16
9. Security Considerations . . . . . . . . . . . . . . . . . . . 14 5.1. Note About Draft Versions . . . . . . . . . . . . . . . . 16
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 6. Prioritization . . . . . . . . . . . . . . . . . . . . . . . 16
10.1. HTTP/3 CAPSULE Frame . . . . . . . . . . . . . . . . . . 14 7. Security Considerations . . . . . . . . . . . . . . . . . . . 17
10.2. HTTP/3 SETTINGS Parameter . . . . . . . . . . . . . . . 15 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
10.3. Capsule Types . . . . . . . . . . . . . . . . . . . . . 15 8.1. HTTP/3 SETTINGS Parameter . . . . . . . . . . . . . . . . 17
10.4. Context Extension Types . . . . . . . . . . . . . . . . 16 8.2. Capsule Types . . . . . . . . . . . . . . . . . . . . . . 17
10.5. Context Close Codes . . . . . . . . . . . . . . . . . . 17 8.3. Datagram Format Types . . . . . . . . . . . . . . . . . . 18
11. Normative References . . . . . . . . . . . . . . . . . . . . 17 8.4. Context Close Codes . . . . . . . . . . . . . . . . . . . 19
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 18 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
A.1. CONNECT-UDP . . . . . . . . . . . . . . . . . . . . . . . 18 9.1. Normative References . . . . . . . . . . . . . . . . . . 19
A.2. CONNECT-UDP with Timestamp Extension . . . . . . . . . . 19 9.2. Informative References . . . . . . . . . . . . . . . . . 20
A.3. CONNECT-IP with IP compression . . . . . . . . . . . . . 20 Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 21
A.4. WebTransport . . . . . . . . . . . . . . . . . . . . . . 21 A.1. CONNECT-UDP . . . . . . . . . . . . . . . . . . . . . . . 21
A.2. CONNECT-UDP with Timestamp Extension . . . . . . . . . . 21
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 22 A.3. CONNECT-IP with IP compression . . . . . . . . . . . . . 22
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22 A.4. WebTransport . . . . . . . . . . . . . . . . . . . . . . 24
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 24
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24
1. Introduction 1. Introduction
The QUIC DATAGRAM extension [DGRAM] provides application protocols The QUIC DATAGRAM extension [DGRAM] provides application protocols
running over QUIC [QUIC] with a mechanism to send unreliable data running over QUIC [QUIC] with a mechanism to send unreliable data
while leveraging the security and congestion-control properties of while leveraging the security and congestion-control properties of
QUIC. However, QUIC DATAGRAM frames do not provide a means to QUIC. However, QUIC DATAGRAM frames do not provide a means to
demultiplex application contexts. This document describes how to use demultiplex application contexts. This document describes how to use
QUIC DATAGRAM frames when the application protocol running over QUIC QUIC DATAGRAM frames when the application protocol running over QUIC
is HTTP/3 [H3]. It associates datagrams with client-initiated is HTTP/3 [H3]. It associates datagrams with client-initiated
bidirectional streams and defines an optional additional bidirectional streams and defines an optional additional
demultiplexing layer. Additionally, this document defines how to demultiplexing layer. Additionally, this document defines how to
convey datagrams over prior versions of HTTP. convey datagrams over prior versions of HTTP.
This document is structured as follows:
* Section 2 presents core concepts for multiplexing across HTTP
versions.
- Section 2.1 defines datagram contexts, an optional end-to-end
multiplexing concept scoped to each HTTP request.
- Section 2.2 defines datagram formats, which are scoped to
contexts. Formats communicate the format and encoding of
datagrams sent using the associated context.
- Contexts are identified using a variable-length integer.
Requirements for allocating identifier values are detailed in
Section 2.3.
* Section 3 defines how QUIC DATAGRAM frames are used with HTTP/3.
Section 5 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.
- The following Capsule types are defined, together with guidance
for defining new types:
o REGISTER_DATAGRAM_CONTEXT Section 4.4.1
o REGISTER_DATAGRAM_NO_CONTEXT Section 4.4.2
o CLOSE_DATAGRAM_CONTEXT Section 4.4.3
o DATAGRAM Section 4.4.4
1.1. Conventions and Definitions 1.1. Conventions and Definitions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
2. Multiplexing 2. Multiplexing
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2.1. Datagram Contexts 2.1. Datagram Contexts
Within the scope of a given HTTP request, contexts provide an Within the scope of a given HTTP request, contexts provide an
additional demultiplexing layer. Contexts determine the encoding of additional demultiplexing layer. Contexts determine the encoding of
datagrams, and can be used to implicitly convey metadata. For datagrams, and can be used to implicitly convey metadata. For
example, contexts can be used for compression to elide some parts of example, contexts can be used for compression to elide some parts of
the datagram: the context identifier then maps to a compression the datagram: the context identifier then maps to a compression
context that the receiver can use to reconstruct the elided data. context that the receiver can use to reconstruct the elided data.
Contexts are optional, their use is negotiated on each request stream Contexts are optional, whether to use them or not is decided by the
using registration capsules, see Section 4.1 and Section 4.2. When client on each request stream using registration capsules, see
contexts are used, they are identified within the scope of a given Section 4.4.1 and Section 4.4.2. When contexts are used, they are
request by a numeric value, referred to as the context ID. A context identified within the scope of a given request by a numeric value,
ID is a 62-bit integer (0 to 2^62-1). referred to as the context ID. A context ID is a 62-bit integer (0
to 2^62-1).
While stream IDs are a per-hop concept, context IDs are an end-to-end While stream IDs are a per-hop concept, context IDs are an end-to-end
concept. In other words, if a datagram travels through one or more concept. In other words, if a datagram travels through one or more
intermediaries on its way from client to server, the stream ID will intermediaries on its way from client to server, the stream ID will
most likely change from hop to hop, but the context ID will remain most likely change from hop to hop, but the context ID will remain
the same. Context IDs are opaque to intermediaries. the same. Context IDs are opaque to intermediaries.
2.2. Context ID Allocation 2.2. Datagram Formats
When an endpoint registers a datagram context (or the lack of
contexts), it communicates the format (i.e., the semantics and
encoding) of datagrams sent using this context. This is
acccomplished by sending a Datagram Format Type as part of the
registration capsule, see Section 4.4.1 and Section 4.4.2. This type
identifier is registered with IANA (see Section 8.3) and allows
applications that use HTTP Datagrams to indicate what the content of
datagrams are. Registration capsules carry a Datagram Format
Additional Data field which allows sending some additional
information that would impact the format of datagrams.
For example, a protocol which proxies IP packets can define a
Datagram Format Type which represents an IP packet. The
corresponding Datagram Format Additional Data field would be empty.
An extension to such a protocol that wishes to compress IP addresses
could define a distinct Datagram Format Type and exchange two IP
addresses via the Datagram Format Additional Data field. Then any
datagrams with that type would contain the IP packet with addresses
elided.
2.3. Context ID Allocation
Implementations of HTTP Datagrams MUST provide a context ID Implementations of HTTP Datagrams MUST provide a context ID
allocation service. That service will allow applications co-located allocation service. That service will allow applications co-located
with HTTP to request a unique context ID that they can subsequently with HTTP to request a unique context ID that they can subsequently
use for their own purposes. The HTTP implementation will then parse use for their own purposes. The HTTP implementation will then parse
the context ID of incoming HTTP Datagrams and use it to deliver the the context ID of incoming HTTP Datagrams and use it to deliver the
frame to the appropriate application context. frame to the appropriate application context.
Even-numbered context IDs are client-initiated, while odd-numbered Even-numbered context IDs are client-initiated, while odd-numbered
context IDs are server-initiated. This means that an HTTP client context IDs are server-initiated. This means that an HTTP client
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HTTP/3 Datagram { HTTP/3 Datagram {
Quarter Stream ID (i), Quarter Stream ID (i),
[Context ID (i)], [Context ID (i)],
HTTP Datagram Payload (..), HTTP Datagram Payload (..),
} }
Figure 1: HTTP/3 DATAGRAM Format Figure 1: HTTP/3 DATAGRAM Format
Quarter Stream ID: A variable-length integer that contains the value Quarter Stream ID: A variable-length integer that contains the value
of the client-initiated bidirectional stream that this datagram is of the client-initiated bidirectional stream that this datagram is
associated with, divided by four. (The division by four stems associated with, divided by four (the division by four stems from
from the fact that HTTP requests are sent on client-initiated the fact that HTTP requests are sent on client-initiated
bidirectional streams, and those have stream IDs that are bidirectional streams, and those have stream IDs that are
divisible by four.) divisible by four). The largest legal QUIC stream ID value is
2^62-1, so the largest legal value of Quarter Stream ID is 2^62-1
/ 4. Receipt of a frame that includes a larger value MUST be
treated as a connection error of type FRAME_ENCODING_ERROR.
Context ID: A variable-length integer indicating the context ID of Context ID: A variable-length integer indicating the context ID of
the datagram (see Section 2.1). Whether or not this field is the datagram (see Section 2.1). Whether or not this field is
present depends on which registration capsules were exchanged on present depends on which registration capsules were exchanged on
the associated stream: if a REGISTER_DATAGRAM_CONTEXT capsule (see the associated stream: if a REGISTER_DATAGRAM_CONTEXT capsule (see
Section 4.1) has been sent or received on this stream, then the Section 4.4.1) has been sent or received on this stream, then the
field is present; if a REGISTER_DATAGRAM_NO_CONTEXT capsule (see field is present; if a REGISTER_DATAGRAM_NO_CONTEXT capsule (see
Section 4.2) has been sent or received, then this field is absent; Section 4.4.2) has been sent or received, then this field is
if neither has been sent or received, then it is not yet possible absent; if neither has been sent or received, then it is not yet
to parse this datagram and the receiver MUST either drop that possible to parse this datagram and the receiver MUST either drop
datagram silently or buffer it temporarily while awaiting the that datagram silently or buffer it temporarily while awaiting the
registration capsule. registration capsule.
HTTP Datagram Payload: The payload of the datagram, whose semantics HTTP Datagram Payload: The payload of the datagram, whose semantics
are defined by individual applications. Note that this field can are defined by individual applications. Note that this field can
be empty. be empty.
Intermediaries parse the Quarter Stream ID field in order to Intermediaries parse the Quarter Stream ID field in order to
associate the QUIC DATAGRAM frame with a stream. If an intermediary associate the QUIC DATAGRAM frame with a stream. If an intermediary
receives a QUIC DATAGRAM frame whose payload is too short to allow receives a QUIC DATAGRAM frame whose payload is too short to allow
parsing the Quarter Stream ID field, the intermediary MUST treat it parsing the Quarter Stream ID field, the intermediary MUST treat it
as an HTTP/3 connection error of type H3_GENERAL_PROTOCOL_ERROR. The as an HTTP/3 connection error of type H3_GENERAL_PROTOCOL_ERROR. The
Context ID field is optional and its use is negotiated end-to-end, Context ID field is optional and whether it is present or not is
see Section 4.2. Therefore intermediaries cannot know whether the decided end-to-end by the client, see Section 4.4.2. Therefore
Context ID field is present or absent and they MUST ignore any HTTP/3 intermediaries cannot know whether the Context ID field is present or
Datagram fields after the Quarter Stream ID. absent and they MUST ignore any HTTP/3 Datagram fields after the
Quarter Stream ID.
Endpoints parse both the Quarter Stream ID field and the Context ID Endpoints parse both the Quarter Stream ID field and the Context ID
field in order to associate the QUIC DATAGRAM frame with a stream and field in order to associate the QUIC DATAGRAM frame with a stream and
context within that stream. If an endpoint receives a QUIC DATAGRAM context within that stream. If an endpoint receives a QUIC DATAGRAM
frame whose payload is too short to allow parsing the Quarter Stream frame whose payload is too short to allow parsing the Quarter Stream
ID field, the endpoint MUST treat it as an HTTP/3 connection error of ID field, the endpoint MUST treat it as an HTTP/3 connection error of
type H3_GENERAL_PROTOCOL_ERROR. If an endpoint receives a QUIC type H3_GENERAL_PROTOCOL_ERROR. If an endpoint receives a QUIC
DATAGRAM frame whose payload is long enough to allow parsing the DATAGRAM frame whose payload is long enough to allow parsing the
Quarter Stream ID field but too short to allow parsing the Context ID Quarter Stream ID field but too short to allow parsing the Context ID
field, the endpoint MUST abruptly terminate the corresponding stream field, the endpoint MUST abruptly terminate the corresponding stream
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longer expected so the endpoint can release related state. Endpoints longer expected so the endpoint can release related state. Endpoints
MAY keep state for a short time to account for reordering. Once the MAY keep state for a short time to account for reordering. Once the
state is released, the endpoint MUST silently drop received state is released, the endpoint MUST silently drop received
associated datagrams. associated datagrams.
If an HTTP/3 datagram is received and its Quarter Stream ID maps to a 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 stream that has not yet been created, the receiver SHALL either drop
that datagram silently or buffer it temporarily while awaiting the that datagram silently or buffer it temporarily while awaiting the
creation of the corresponding stream. creation of the corresponding stream.
4. CAPSULE HTTP/3 Frame Definition 4. Capsules
CAPSULE allows reliably sending request-related information end-to- This specification introduces the Capsule Protocol. The Capsule
Protocol is a sequence of type-length-value tuples that allows
endpoints to reliably communicate request-related information end-to-
end, even in the presence of HTTP intermediaries. end, even in the presence of HTTP intermediaries.
CAPSULE is an HTTP/3 Frame (as opposed to a QUIC frame) which SHALL 4.1. Capsule Protocol
only be sent in client-initiated bidirectional streams.
Intermediaries forward received CAPSULE frames on the same stream
where it would forward DATA frames. Each Capsule Type determines
whether it is opaque or transparent to intermediaries: opaque
capsules are forwarded unmodified while transparent ones can be
parsed, added, or removed by intermediaries.
This specification of CAPSULE currently uses HTTP/3 frame type This specification defines the "data stream" of an HTTP request as
0xffcab5. If this document is approved, a lower number will be the bidirectional stream of bytes that follow the headers in both
requested from IANA. 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. 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.
CAPSULE HTTP/3 Frame { Definitions of new HTTP Methods or of new HTTP Upgrade Tokens can
Type (i) = 0xffcab5, state that their data stream uses the Capsule Protocol. If they do
Length (i), 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 Type (i),
Capsule Data (..), Capsule Length (i),
Capsule Value (..),
} }
Figure 2: CAPSULE HTTP/3 Frame Format Figure 3: Capsule Format
The Type and Length fields follows the definition of HTTP/3 frames Capsule Type: A variable-length integer indicating the Type of the
from [H3]. The payload consists of: capsule. Endpoints that receive a capsule with an unknown Capsule
Type MUST silently skip over that capsule.
Capsule Type: The type of this 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 Data: Data whose semantics depends on the Capsule Type. Capsule Value: The payload of this capsule. Its semantics are
determined by the value of the Capsule Type field.
4.2. Requirements
If the definition of an HTTP Method or HTTP Upgrade Token states that
it uses the capsule protocol, its implementations MUST follow the
following requirements:
* A server MUST NOT send any Transfer-Encoding or Content-Length
header fields in a 2xx (Successful) response. If a client
receives a Content-Length or Transfer-Encoding header fields in a
successful response, it MUST treat that response as malformed.
* A request message does not have content.
* A successful response message does not have content.
* Responses are not cacheable.
4.3. Intermediary Processing
Intermediaries MUST operate in one of the two following modes:
Pass-through mode: In this mode, the intermediary forwards the data
stream between two associated streams without any modification of
the data stream.
Participant mode: In this mode, the intermediary terminates the data
stream and parses all Capsule Type and Capsule Length fields it
receives.
Each Capsule Type determines whether it is opaque or transparent to
intermediaries in participant mode: opaque capsules are forwarded
unmodified while transparent ones can be parsed, added, or removed by
intermediaries. Intermediaries MAY modify the contents of the
Capsule Data field of transparent capsule types.
Unless otherwise specified, all Capsule Types are defined as opaque Unless otherwise specified, all Capsule Types are defined as opaque
to intermediaries. Intermediaries MUST forward all received opaque to intermediaries. Intermediaries MUST forward all received opaque
CAPSULE frames in their unmodified entirety. Intermediaries MUST NOT CAPSULE frames in their unmodified entirety. Intermediaries MUST NOT
send any opaque CAPSULE frames other than the ones it is forwarding. send any opaque CAPSULE frames other than the ones it is forwarding.
All Capsule Types defined in this document are opaque, with the All Capsule Types defined in this document are opaque, with the
exception of the DATAGRAM Capsule, see Section 4.4. Definitions of exception of the DATAGRAM Capsule, see Section 4.4.4. Definitions of
new Capsule Types MAY specify that the newly introduced type is new Capsule Types MAY specify that the newly introduced type is
transparent. Intermediaries MUST treat unknown Capsule Types as transparent. Intermediaries MUST treat unknown Capsule Types as
opaque. opaque.
Intermediaries respect the order of opaque CAPSULE frames: if an Intermediaries respect the order of opaque CAPSULE frames: if an
intermediary receives two opaque CAPSULE frames in a given order, it intermediary receives two opaque CAPSULE frames in a given order, it
MUST forward them in the same order. MUST forward them in the same order.
Endpoints which receive a Capsule with an unknown Capsule Type MUST Endpoints which receive a Capsule with an unknown Capsule Type MUST
silently drop that Capsule. silently drop that Capsule.
Receipt of a CAPSULE HTTP/3 Frame on a stream that is not a client- 4.4. Capsule Types
initiated bidirectional stream MUST be treated as a connection error
of type H3_FRAME_UNEXPECTED.
4.1. The REGISTER_DATAGRAM_CONTEXT Capsule 4.4.1. The REGISTER_DATAGRAM_CONTEXT Capsule
The REGISTER_DATAGRAM_CONTEXT capsule (type=0x00) allows an endpoint The REGISTER_DATAGRAM_CONTEXT capsule (see Section 8.2 for the value
to inform its peer of the encoding and semantics of datagrams of the capsule type) allows an endpoint to inform its peer of the
associated with a given context ID. Its Capsule Data field consists encoding and semantics of datagrams associated with a given context
of: ID.
REGISTER_DATAGRAM_CONTEXT Capsule { REGISTER_DATAGRAM_CONTEXT Capsule {
Type (i) = REGISTER_DATAGRAM_CONTEXT,
Length (i),
Context ID (i), Context ID (i),
Context Extensions (..), Datagram Format Type (i),
Datagram Format Additional Data (..),
} }
Figure 3: REGISTER_DATAGRAM_CONTEXT Capsule Format Figure 4: REGISTER_DATAGRAM_CONTEXT Capsule Format
Context ID: The context ID to register. Context ID: The context ID to register.
Context Extensions: See Section 5. Datagram Format Type: A variable-length integer that defines the
semantics and encoding of the HTTP Datagram Payload field of
datagrams with this context ID, see Section 2.2.
Datagram Format Additional Data: This field carries additional
information that impact the format of datagrams with this context
ID, see Section 2.2.
Note that these registrations are unilateral and bidirectional: the Note that these registrations are unilateral and bidirectional: the
sender of the frame unilaterally defines the semantics it will apply sender of the frame unilaterally defines the semantics it will apply
to the datagrams it sends and receives using this context ID. Once a to the datagrams it sends and receives using this context ID. Once a
context ID is registered, it can be used in both directions. context ID is registered, it can be used in both directions.
Endpoints MUST NOT send DATAGRAM frames using a Context ID until they Endpoints MUST NOT send DATAGRAM frames using a Context ID until they
have either sent or received a REGISTER_DATAGRAM_CONTEXT Capsule with have either sent or received a REGISTER_DATAGRAM_CONTEXT Capsule with
the same Context ID. However, due to reordering, an endpoint that the same Context ID. However, reordering can cause DATAGRAM frames
receives a DATAGRAM frame with an unknown Context ID MUST NOT treat to be received with an unknown Context ID. Receipt of such frames
it as an error, it SHALL instead drop the DATAGRAM frame silently, or MUST NOT be treated as an error. Endpoints SHALL drop the DATAGRAM
buffer it temporarily while awaiting the corresponding frame silently, or buffer it temporarily while awaiting the
REGISTER_DATAGRAM_CONTEXT Capsule. corresponding REGISTER_DATAGRAM_CONTEXT Capsule. Intermediaries
SHALL drop the DATAGRAM frame silently, MAY buffer it, or forward it
on immediately.
Endpoints MUST NOT register the same Context ID twice on the same Endpoints MUST NOT register the same Context ID twice on the same
stream. This also applies to Context IDs that have been closed using stream. This also applies to Context IDs that have been closed using
a CLOSE_DATAGRAM_CONTEXT capsule. Clients MUST NOT register server- a CLOSE_DATAGRAM_CONTEXT capsule. Clients MUST NOT register server-
initiated Context IDs and servers MUST NOT register client-initiated initiated Context IDs and servers MUST NOT register client-initiated
Context IDs. If an endpoint receives a REGISTER_DATAGRAM_CONTEXT Context IDs. If an endpoint receives a REGISTER_DATAGRAM_CONTEXT
capsule that violates one or more of these requirements, the endpoint capsule that violates one or more of these requirements, the endpoint
MUST abruptly terminate the corresponding stream with a stream error MUST abruptly terminate the corresponding stream with a stream error
of type H3_GENERAL_PROTOCOL_ERROR. of type H3_GENERAL_PROTOCOL_ERROR.
Endpoints MUST NOT send a REGISTER_DATAGRAM_CONTEXT capsule on a
stream before they have sent at least one HEADERS frame on that
stream. This removes the need to buffer REGISTER_DATAGRAM_CONTEXT
capsules when the endpoint needs information from headers to
determine how to react to the capsule. If an endpoint receives a
REGISTER_DATAGRAM_CONTEXT capsule on a stream that hasn't yet
received a HEADERS frame, the endpoint MUST abruptly terminate the
corresponding stream with a stream error of type
H3_GENERAL_PROTOCOL_ERROR.
Servers MUST NOT send a REGISTER_DATAGRAM_CONTEXT capsule on a stream Servers MUST NOT send a REGISTER_DATAGRAM_CONTEXT capsule on a stream
before they have received at least one REGISTER_DATAGRAM_CONTEXT before they have received at least one REGISTER_DATAGRAM_CONTEXT
capsule or one REGISTER_DATAGRAM_NO_CONTEXT capsule from the client capsule or one REGISTER_DATAGRAM_NO_CONTEXT capsule from the client
on that stream. This ensures that clients control whether datagrams on that stream. This ensures that clients control whether datagrams
are allowed for a given request. If a client receives a are allowed for a given request. If a client receives a
REGISTER_DATAGRAM_CONTEXT capsule on a stream where the client has REGISTER_DATAGRAM_CONTEXT capsule on a stream where the client has
not yet sent a REGISTER_DATAGRAM_CONTEXT capsule, the client MUST not yet sent a REGISTER_DATAGRAM_CONTEXT capsule, the client MUST
abruptly terminate the corresponding stream with a stream error of abruptly terminate the corresponding stream with a stream error of
type H3_GENERAL_PROTOCOL_ERROR. type H3_GENERAL_PROTOCOL_ERROR.
Servers MUST NOT send a REGISTER_DATAGRAM_CONTEXT capsule on a stream Servers MUST NOT send a REGISTER_DATAGRAM_CONTEXT capsule on a stream
where it has received a REGISTER_DATAGRAM_NO_CONTEXT capsule. If a where it has received a REGISTER_DATAGRAM_NO_CONTEXT capsule. If a
client receives a REGISTER_DATAGRAM_CONTEXT capsule on a stream where client receives a REGISTER_DATAGRAM_CONTEXT capsule on a stream where
the client has sent a REGISTER_DATAGRAM_NO_CONTEXT capsule, the the client has sent a REGISTER_DATAGRAM_NO_CONTEXT capsule, the
client MUST abruptly terminate the corresponding stream with a stream client MUST abruptly terminate the corresponding stream with a stream
error of type H3_GENERAL_PROTOCOL_ERROR. error of type H3_GENERAL_PROTOCOL_ERROR.
4.2. The REGISTER_DATAGRAM_NO_CONTEXT Capsule 4.4.2. The REGISTER_DATAGRAM_NO_CONTEXT Capsule
The REGISTER_DATAGRAM_NO_CONTEXT capsule (type=0x03) allows a client The REGISTER_DATAGRAM_NO_CONTEXT capsule (see Section 8.2 for the
to inform the server that datagram contexts will not be used with value of the capsule type) allows a client to inform the server that
this stream. It also informs the server of the encoding and datagram contexts will not be used with this stream. It also informs
semantics of datagrams associated with this stream. Its Capsule Data the server of the encoding and semantics of datagrams associated with
field consists of: this stream.
REGISTER_DATAGRAM_NO_CONTEXT Capsule { REGISTER_DATAGRAM_NO_CONTEXT Capsule {
Context Extensions (..), Type (i) = REGISTER_DATAGRAM_NO_CONTEXT,
Length (i),
Datagram Format Type (i),
Datagram Format Additional Data (..),
} }
Figure 4: REGISTER_DATAGRAM_NO_CONTEXT Capsule Format Figure 5: REGISTER_DATAGRAM_NO_CONTEXT Capsule Format
Context Extensions: See Section 5. Datagram Format Type: A variable-length integer that defines the
semantics and encoding of the HTTP Datagram Payload field of
datagrams, see Section 2.2.
Datagram Format Additional Data: This field carries additional
information that impact the format of datagrams, see Section 2.2.
Note that this registration is unilateral and bidirectional: the Note that this registration is unilateral and bidirectional: the
client unilaterally defines the semantics it will apply to the client unilaterally defines the semantics it will apply to the
datagrams it sends and receives with this stream. datagrams it sends and receives with this stream.
Endpoints MUST NOT send DATAGRAM frames without a Context ID until Endpoints MUST NOT send DATAGRAM frames without a Context ID until
they have either sent or received a REGISTER_DATAGRAM_NO_CONTEXT they have either sent or received a REGISTER_DATAGRAM_NO_CONTEXT
Capsule. However, due to reordering, an endpoint that receives a Capsule. However, due to reordering, an endpoint that receives a
DATAGRAM frame before receiving either a REGISTER_DATAGRAM_CONTEXT DATAGRAM frame before receiving either a REGISTER_DATAGRAM_CONTEXT
capsule or a REGISTER_DATAGRAM_NO_CONTEXT capsule MUST NOT treat it capsule or a REGISTER_DATAGRAM_NO_CONTEXT capsule MUST NOT treat it
skipping to change at page 10, line 5 skipping to change at page 12, line 30
client receives a REGISTER_DATAGRAM_NO_CONTEXT capsule, the client client receives a REGISTER_DATAGRAM_NO_CONTEXT capsule, the client
MUST abruptly terminate the corresponding stream with a stream error MUST abruptly terminate the corresponding stream with a stream error
of type H3_GENERAL_PROTOCOL_ERROR. of type H3_GENERAL_PROTOCOL_ERROR.
Clients MUST NOT send more than one REGISTER_DATAGRAM_NO_CONTEXT Clients MUST NOT send more than one REGISTER_DATAGRAM_NO_CONTEXT
capsule on a stream. If a server receives a second capsule on a stream. If a server receives a second
REGISTER_DATAGRAM_NO_CONTEXT capsule on the same stream, the server REGISTER_DATAGRAM_NO_CONTEXT capsule on the same stream, the server
MUST abruptly terminate the corresponding stream with a stream error MUST abruptly terminate the corresponding stream with a stream error
of type H3_GENERAL_PROTOCOL_ERROR. of type H3_GENERAL_PROTOCOL_ERROR.
Clients MUST NOT send a REGISTER_DATAGRAM_NO_CONTEXT capsule on a
stream before they have sent at least one HEADERS frame on that
stream. This removes the need to buffer REGISTER_DATAGRAM_CONTEXT
capsules when the server needs information from headers to determine
how to react to the capsule. If a server receives a
REGISTER_DATAGRAM_NO_CONTEXT capsule on a stream that hasn't yet
received a HEADERS frame, the server MUST abruptly terminate the
corresponding stream with a stream error of type
H3_GENERAL_PROTOCOL_ERROR.
Clients MUST NOT send both REGISTER_DATAGRAM_CONTEXT capsules and Clients MUST NOT send both REGISTER_DATAGRAM_CONTEXT capsules and
REGISTER_DATAGRAM_NO_CONTEXT capsules on the same stream. If a REGISTER_DATAGRAM_NO_CONTEXT capsules on the same stream. If a
server receives both a REGISTER_DATAGRAM_CONTEXT capsule and a server receives both a REGISTER_DATAGRAM_CONTEXT capsule and a
REGISTER_DATAGRAM_NO_CONTEXT capsule on the same stream, the server REGISTER_DATAGRAM_NO_CONTEXT capsule on the same stream, the server
MUST abruptly terminate the corresponding stream with a stream error MUST abruptly terminate the corresponding stream with a stream error
of type H3_GENERAL_PROTOCOL_ERROR. of type H3_GENERAL_PROTOCOL_ERROR.
Extensions MAY define a different mechanism to negotiate the presence Extensions MAY define a different mechanism to communicate whether
of contexts, and they MAY do so in a way which is opaque to contexts are in use, and they MAY do so in a way which is opaque to
intermediaries. intermediaries.
4.3. The CLOSE_DATAGRAM_CONTEXT Capsule 4.4.3. The CLOSE_DATAGRAM_CONTEXT Capsule
The CLOSE_DATAGRAM_CONTEXT capsule (type=0x01) allows an endpoint to The CLOSE_DATAGRAM_CONTEXT capsule (see Section 8.2 for the value of
inform its peer that it will no longer send or parse received the capsule type) allows an endpoint to inform its peer that it will
datagrams associated with a given context ID. Its Capsule Data field no longer send or parse received datagrams associated with a given
consists of: context ID.
CLOSE_DATAGRAM_CONTEXT Capsule { CLOSE_DATAGRAM_CONTEXT Capsule {
Type (i) = CLOSE_DATAGRAM_CONTEXT,
Length (i),
Context ID (i), Context ID (i),
Context Extensions (..), Close Code (i),
Close Details (..),
} }
Figure 5: CLOSE_DATAGRAM_CONTEXT Capsule Format Figure 6: CLOSE_DATAGRAM_CONTEXT Capsule Format
Context ID: The context ID to close. Context ID: The context ID to close.
Context Extensions: See Section 5. Close Code: The close code allows an endpoint to provide additional
information as to why a datagram context was closed.
Section 4.4.3.1 defines a set of codes, the circumstances under
which an implementation sends them, and how receivers react.
Close Details: This is meant for debugging purposes. It consists of
a human-readable string encoded in UTF-8.
Note that this close is unilateral and bidirectional: the sender of Note that this close is unilateral and bidirectional: the sender of
the frame unilaterally informs its peer of the closure. Endpoints the frame unilaterally informs its peer of the closure. Endpoints
can use CLOSE_DATAGRAM_CONTEXT capsules to close a context that was can use CLOSE_DATAGRAM_CONTEXT capsules to close a context that was
initially registered by either themselves, or by their peer. initially registered by either themselves, or by their peer.
Endpoints MAY use the CLOSE_DATAGRAM_CONTEXT capsule to immediately Endpoints MAY use the CLOSE_DATAGRAM_CONTEXT capsule to immediately
reject a context that was just registered using a reject a context that was just registered using a
REGISTER_DATAGRAM_CONTEXT capsule if they find its Context Extensions REGISTER_DATAGRAM_CONTEXT capsule if they find its Datagram Format
field to be unacceptable. Type field to be unacceptable.
After an endpoint has either sent or received a After an endpoint has either sent or received a
CLOSE_DATAGRAM_CONTEXT frame, it MUST NOT send any DATAGRAM frames CLOSE_DATAGRAM_CONTEXT frame, it MUST NOT send any DATAGRAM frames
with that Context ID. However, due to reordering, an endpoint that with that Context ID. However, due to reordering, an endpoint that
receives a DATAGRAM frame with a closed Context ID MUST NOT treat it receives a DATAGRAM frame with a closed Context ID MUST NOT treat it
as an error, it SHALL instead drop the DATAGRAM frame silently. as an error, it SHALL instead drop the DATAGRAM frame silently.
Endpoints MUST NOT close a Context ID that was not previously Endpoints MUST NOT close a Context ID that was not previously
registered. Endpoints MUST NOT close a Context ID that has already registered. Endpoints MUST NOT close a Context ID that has already
been closed. If an endpoint receives a CLOSE_DATAGRAM_CONTEXT been closed. If an endpoint receives a CLOSE_DATAGRAM_CONTEXT
capsule that violates one or more of these requirements, the endpoint capsule that violates one or more of these requirements, the endpoint
MUST abruptly terminate the corresponding stream with a stream error MUST abruptly terminate the corresponding stream with a stream error
of type H3_GENERAL_PROTOCOL_ERROR. of type H3_GENERAL_PROTOCOL_ERROR.
All CLOSE_DATAGRAM_CONTEXT capsules MUST contain a CLOSE_CODE context 4.4.3.1. Close Codes
extension, see Section 5.1. If an endpoint receives a
CLOSE_DATAGRAM_CONTEXT capsule without a CLOSE_CODE context
extension, the endpoint MUST abruptly terminate the corresponding
stream with a stream error of type H3_GENERAL_PROTOCOL_ERROR.
4.4. The DATAGRAM Capsule Close codes are intended to allow implementations to react
differently when they receive them - for example, some close codes
require the receiver to not open another context under certain
conditions.
The DATAGRAM capsule (type=0x02) allows an endpoint to send a This specification defines the close codes below. Their numeric
datagram frame over an HTTP stream. This is particularly useful when values are in Section 8.4. Extensions to this mechanism MAY define
using a version of HTTP that does not support QUIC DATAGRAM frames. new close codes and they SHOULD state how receivers react to them.
Its Capsule Data field consists of:
NO_ERROR: This indicates that a context was closed without any
action specified for the receiver.
UNKNOWN_FORMAT: This indicates that the sender does not know how to
interpret the datagram format type associated with this context.
The endpoint that had originally registered this context MUST NOT
try to register another context with the same datagram format type
on this stream.
DENIED: This indicates that the sender has rejected the context
registration based on its local policy. The endpoint that had
originally registered this context MUST NOT try to register
another context with the same datagram format type and datagram
format data on this stream.
RESOURCE_LIMIT: This indicates that the context was closed to save
resources. The recipient SHOULD limit its future registration of
resource-intensive contexts.
Receipt of an unknown close code MUST be treated as if the NO_ERROR
code was present. Close codes are registered with IANA, see
Section 8.4.
4.4.4. The DATAGRAM Capsule
The DATAGRAM capsule (see Section 8.2 for the value of the capsule
type) allows an endpoint to send a datagram frame over an HTTP
stream. This is particularly useful when using a version of HTTP
that does not support QUIC DATAGRAM frames.
DATAGRAM Capsule { DATAGRAM Capsule {
Type (i) = DATAGRAM,
Length (i),
[Context ID (i)], [Context ID (i)],
HTTP Datagram Payload (..), HTTP Datagram Payload (..),
} }
Figure 6: DATAGRAM Capsule Format Figure 7: DATAGRAM Capsule Format
Context ID: A variable-length integer indicating the context ID of Context ID: A variable-length integer indicating the context ID of
the datagram (see Section 2.1). Whether or not this field is the datagram (see Section 2.1). Whether or not this field is
present depends on which registration capsules were exchanged on present depends on which registration capsules were exchanged on
the associated stream: if a REGISTER_DATAGRAM_CONTEXT capsule (see the associated stream: if a REGISTER_DATAGRAM_CONTEXT capsule (see
Section 4.1) has been sent or received on this stream, then the Section 4.4.1) has been sent or received on this stream, then the
field is present; if a REGISTER_DATAGRAM_NO_CONTEXT capsule (see field is present; if a REGISTER_DATAGRAM_NO_CONTEXT capsule (see
Section 4.2) has been sent or received, then this field is absent; Section 4.4.2) has been sent or received, then this field is
if neither has been sent or received, then it is not yet possible absent; if neither has been sent or received, then it is not yet
to parse this datagram and the receiver MUST either drop that possible to parse this datagram and the receiver MUST either drop
datagram silently or buffer it temporarily while awaiting the that datagram silently or buffer it temporarily while awaiting the
registration capsule. registration capsule.
HTTP Datagram Payload: The payload of the datagram, whose semantics HTTP Datagram Payload: The payload of the datagram, whose semantics
are defined by individual applications. Note that this field can are defined by individual applications. Note that this field can
be empty. be empty.
Datagrams sent using the DATAGRAM Capsule have the exact same Datagrams sent using the DATAGRAM Capsule have the exact same
semantics as datagrams sent in QUIC DATAGRAM frames. In particular, semantics as datagrams sent in QUIC DATAGRAM frames. In particular,
the restrictions on when it is allowed to send an HTTP Datagram and 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 how to process them from Section 3 also apply to HTTP Datagrams sent
skipping to change at page 12, line 24 skipping to change at page 15, line 34
as it forwards them: in other words, an intermediary MAY send a as it forwards them: in other words, an intermediary MAY send a
DATAGRAM Capsule to forward an HTTP Datagram which was received in a DATAGRAM Capsule to forward an HTTP Datagram which was received in a
QUIC DATAGRAM frame, and vice versa. QUIC DATAGRAM frame, and vice versa.
Note that while DATAGRAM capsules are sent on a stream, Note that while DATAGRAM capsules are sent on a stream,
intermediaries can reencode HTTP Datagrams into QUIC DATAGRAM frames intermediaries can reencode HTTP Datagrams into QUIC DATAGRAM frames
over the next hop, and those could be dropped. Because of this, over the next hop, and those could be dropped. Because of this,
applications have to always consider HTTP Datagrams to be unreliable, applications have to always consider HTTP Datagrams to be unreliable,
even if they were initially sent in a capsule. even if they were initially sent in a capsule.
5. Context Extensibility If an intermediary receives an HTTP Datagram in a QUIC DATAGRAM frame
and is forwarding it on a connection that supports QUIC DATAGRAM
In order to facilitate extensibility of contexts, the frames, the intermediary SHOULD NOT convert that HTTP Datagram to a
REGISTER_DATAGRAM_CONTEXT, REGISTER_DATAGRAM_NO_CONTEXT, and the DATAGRAM capsule. If the HTTP Datagram is too large to fit in a
CLOSE_DATAGRAM_CONTEXT capsules carry a Context Extensions field. DATAGRAM frame (for example because the path MTU of that QUIC
That field contains a sequence of context extensions: connection is too low or if the maximum UDP payload size advertised
on that connection is too low), the intermediary SHOULD drop the HTTP
Context Extensions { Datagram instead of converting it to a DATAGRAM capsule. This
Context Extension (..) ..., preserves the end-to-end unreliability characteristic that methods
} such as Datagram Packetization Layer Path MTU Discovery (DPLPMTUD)
depend on [RFC8899]. An intermediary that converts QUIC DATAGRAM
Each context extension is encoded as a (type, length, value) tuple: frames to DATAGRAM capsules allows HTTP Datagrams to be arbitrarily
large without suffering any loss; this can misrepresent the true path
Context Extension { properties, defeating methods such a DPLPMTUD.
Context Extension Type (i),
Context Extension Length (i),
Context Extension Value (..),
}
Context Extension Types are registered with IANA, see Section 10.4.
The Context Extension Length field contains the length of the Context
Extension Value field in bytes. The semantics of the Context
Extension Value field are defined by the corresponding Context
Extension Type.
5.1. The CLOSE_CODE Context Extension Type
The CLOSE_CODE context extension type (type=0x00) allows an endpoint
to provide additional information as to why a datagram context was
closed. This type SHALL only be sent in CLOSE_DATAGRAM_CONTEXT
capsules. Its Context Extension Value field consists of a single
variable-length integer which contains the close code. The following
codes are defined:
NO_ERROR (code=0x00): This indicates that the registration was
closed without any additional information.
DENIED (code=0x01): This indicates that the sender has rejected the
context registration based on its local policy. The endpoint that
had originally registered this context MUST NOT try to register
another context with the same context extensions on this stream.
RESOURCE_LIMIT (code=0x02): This indicates that the context was
closed to save resources. The recipient SHOULD limit its future
registration of resource-incentive contexts.
Receipt of an unknown close code MUST be treated as if the NO_ERROR
code was present. Close codes are registered with IANA, see
Section 10.5.
5.2. The DETAILS Context Extension Type
The DETAILS context extension type (type=0x01) allows an endpoint to
provide additional details to context capsules. It is meant for
debugging purposes. Its Context Extension Value field consists of a
human-readable string encoded in UTF-8.
6. The H3_DATAGRAM HTTP/3 SETTINGS Parameter 5. The H3_DATAGRAM HTTP/3 SETTINGS Parameter
Implementations of HTTP/3 that support this mechanism can indicate Implementations of HTTP/3 that support HTTP Datagrams can indicate
that to their peer by sending the H3_DATAGRAM SETTINGS parameter with 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 a value of 1. The value of the H3_DATAGRAM SETTINGS parameter MUST
be either 0 or 1. A value of 0 indicates that this mechanism is not be either 0 or 1. A value of 0 indicates that HTTP Datagrams are not
supported. An endpoint that receives the H3_DATAGRAM SETTINGS supported. An endpoint that receives the H3_DATAGRAM SETTINGS
parameter with a value that is neither 0 or 1 MUST terminate the parameter with a value that is neither 0 or 1 MUST terminate the
connection with error H3_SETTINGS_ERROR. connection with error H3_SETTINGS_ERROR.
An endpoint that sends the H3_DATAGRAM SETTINGS parameter with a Endpoints MUST NOT send QUIC DATAGRAM frames until they have both
value of 1 MUST send the max_datagram_frame_size QUIC Transport sent and received the H3_DATAGRAM SETTINGS parameter with a value of
Parameter [DGRAM]. An endpoint that receives the H3_DATAGRAM 1.
SETTINGS parameter with a value of 1 on a QUIC connection that did
not also receive the max_datagram_frame_size QUIC Transport Parameter
MUST terminate the connection with error H3_SETTINGS_ERROR.
When clients use 0-RTT, they MAY store the value of the server's When clients use 0-RTT, they MAY store the value of the server's
H3_DATAGRAM SETTINGS parameter. Doing so allows the client to use H3_DATAGRAM SETTINGS parameter. Doing so allows the client to send
HTTP/3 datagrams in 0-RTT packets. When servers decide to accept QUIC DATAGRAM frames in 0-RTT packets. When servers decide to accept
0-RTT data, they MUST send a H3_DATAGRAM SETTINGS parameter greater 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 than or equal to the value they sent to the client in the connection
where they sent them the NewSessionTicket message. If a client where they sent them the NewSessionTicket message. If a client
stores the value of the H3_DATAGRAM SETTINGS parameter with their 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 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 SETTINGS parameter sent by the server in the handshake is greater
than or equal to the stored value; if not, the client MUST terminate than or equal to the stored value; if not, the client MUST terminate
the connection with error H3_SETTINGS_ERROR. In all cases, the the connection with error H3_SETTINGS_ERROR. In all cases, the
maximum permitted value of the H3_DATAGRAM SETTINGS parameter is 1. maximum permitted value of the H3_DATAGRAM SETTINGS parameter is 1.
7. Prioritization 5.1. Note About Draft Versions
Prioritization of HTTP/3 datagrams is not defined in this document. [[RFC editor: please remove this section before publication.]]
Future extensions MAY define how to prioritize datagrams, and MAY
define signaling to allow endpoints to communicate their
prioritization preferences.
8. HTTP/1.x and HTTP/2 Support 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.
We can provide DATAGRAM support in HTTP/2 by defining the CAPSULE 6. Prioritization
frame in HTTP/2.
We can provide DATAGRAM support in HTTP/1.x by defining its data Data streams (see Section 4.1) can be prioritized using any means
stream format to a sequence of length-value capsules. suited to stream or request prioritization. For example, see
Section 11 of [PRIORITY].
TODO: Refactor this document and add definitions for HTTP/1.x and Prioritization of HTTP/3 datagrams is not defined in this document.
HTTP/2. Future extensions MAY define how to prioritize datagrams, and MAY
define signaling to allow endpoints to communicate their
prioritization preferences.
9. Security Considerations 7. Security Considerations
Since this feature requires sending an HTTP/3 Settings parameter, it Since this feature requires sending an HTTP/3 Settings parameter, it
"sticks out". In other words, probing clients can learn whether a "sticks out". In other words, probing clients can learn whether a
server supports this feature. Implementations that support this server supports this feature. Implementations that support this
feature SHOULD always send this Settings parameter to avoid leaking feature SHOULD always send this Settings parameter to avoid leaking
the fact that there are applications using HTTP/3 datagrams enabled the fact that there are applications using HTTP/3 datagrams enabled
on this endpoint. on this endpoint.
10. IANA Considerations 8. IANA Considerations
10.1. HTTP/3 CAPSULE Frame
This document will request IANA to register the following entry in
the "HTTP/3 Frames" registry:
+------------+----------+---------------+
| Frame Type | Value | Specification |
+============+==========+===============+
| CAPSULE | 0xffcab5 | This Document |
+------------+----------+---------------+
10.2. HTTP/3 SETTINGS Parameter 8.1. HTTP/3 SETTINGS Parameter
This document will request IANA to register the following entry in This document will request IANA to register the following entry in
the "HTTP/3 Settings" registry: the "HTTP/3 Settings" registry:
+--------------+----------+---------------+---------+ +==============+==========+===============+=========+
| Setting Name | Value | Specification | Default | | Setting Name | Value | Specification | Default |
+==============+==========+===============+=========+ +==============+==========+===============+=========+
| H3_DATAGRAM | 0xffd276 | This Document | 0 | | H3_DATAGRAM | 0xffd277 | This Document | 0 |
+--------------+----------+---------------+---------+ +--------------+----------+---------------+---------+
10.3. Capsule Types Table 1: New HTTP/3 Settings
8.2. Capsule Types
This document establishes a registry for HTTP capsule type codes. This document establishes a registry for HTTP capsule type codes.
The "HTTP Capsule Types" registry governs a 62-bit space. The "HTTP Capsule Types" registry governs a 62-bit space.
Registrations in this registry MUST include the following fields: Registrations in this registry MUST include the following fields:
Type: Type: A name or label for the capsule type.
A name or label for the capsule type.
Value: The value of the Capsule Type field (see Section 4) is a Value: The value of the Capsule Type field (see Section 4.1) is a
62bit integer. 62-bit integer.
Reference: An optional reference to a specification for the type. Reference: An optional reference to a specification for the type.
This field MAY be empty. This field MAY be empty.
Registrations follow the "First Come First Served" policy (see Registrations follow the "First Come First Served" policy (see
Section 4.4 of [IANA-POLICY]) where two registrations MUST NOT have Section 4.4 of [IANA-POLICY]) where two registrations MUST NOT have
the same Type. the same Type.
This registry initially contains the following entries: This registry initially contains the following entries:
+------------------------------+-------+---------------+ +==============================+==========+===============+
| Capsule Type | Value | Specification | | Capsule Type | Value | Specification |
+------------------------------+-------+---------------+ +==============================+==========+===============+
| REGISTER_DATAGRAM_CONTEXT | 0x00 | This Document | | DATAGRAM | 0xff37a0 | This Document |
+------------------------------+-------+---------------+ +------------------------------+----------+---------------+
| CLOSE_DATAGRAM_CONTEXT | 0x01 | This Document | | REGISTER_DATAGRAM_CONTEXT | 0xff37a1 | This Document |
+------------------------------+-------+---------------+ +------------------------------+----------+---------------+
| DATAGRAM | 0x02 | This Document | | REGISTER_DATAGRAM_NO_CONTEXT | 0xff37a2 | This Document |
+------------------------------+-------+---------------+ +------------------------------+----------+---------------+
| REGISTER_DATAGRAM_NO_CONTEXT | 0x03 | This Document | | CLOSE_DATAGRAM_CONTEXT | 0xff37a3 | This Document |
+------------------------------+-------+---------------+ +------------------------------+----------+---------------+
Table 2: Initial Capsule Types Registry Entries
Capsule types with a value of the form 41 * N + 23 for integer values 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 of N are reserved to exercise the requirement that unknown capsule
types be ignored. These capsules have no semantics and can carry types be ignored. These capsules have no semantics and can carry
arbitrary values. These values MUST NOT be assigned by IANA and MUST arbitrary values. These values MUST NOT be assigned by IANA and MUST
NOT appear in the listing of assigned values. NOT appear in the listing of assigned values.
10.4. Context Extension Types 8.3. Datagram Format Types
This document establishes a registry for HTTP datagram context
extension type codes. The "HTTP Context Extension Types" registry
governs a 62-bit space. Registrations in this registry MUST include
the following fields:
Type: This document establishes a registry for HTTP datagram format type
codes. The "HTTP Datagram Format Types" registry governs a 62-bit
space. Registrations in this registry MUST include the following
fields:
A name or label for the context extension type. Type: A name or label for the datagram format type.
Value: The value of the Context Extension Type field (see Section 5) Value: The value of the Datagram Format Type field (see Section 2.2)
is a 62bit integer. is a 62-bit integer.
Reference: An optional reference to a specification for the Reference: An optional reference to a specification for the
parameter. This field MAY be empty. parameter. This field MAY be empty.
Registrations follow the "First Come First Served" policy (see Registrations follow the "First Come First Served" policy (see
Section 4.4 of [IANA-POLICY]) where two registrations MUST NOT have Section 4.4 of [IANA-POLICY]) where two registrations MUST NOT have
the same Type nor Value. the same Type nor Value.
This registry initially contains the following entries: This registry is initially empty.
+------------------------------+-------+---------------+ Datagram format types with a value of the form 41 * N + 17 for
| Context Extension Type | Value | Specification |
+------------------------------+-------+---------------+
| CLOSE_CODE | 0x00 | This Document |
+------------------------------+-------+---------------+
| DETAILS | 0x01 | This Document |
+------------------------------+-------+---------------+
Context extension types with a value of the form 41 * N + 17 for
integer values of N are reserved to exercise the requirement that integer values of N are reserved to exercise the requirement that
unknown context extension types be ignored. These extensions have no unknown datagram format types be ignored. These format types have no
semantics and can carry arbitrary values. These values MUST NOT be semantics and can carry arbitrary values. These values MUST NOT be
assigned by IANA and MUST NOT appear in the listing of assigned assigned by IANA and MUST NOT appear in the listing of assigned
values. values.
10.5. Context Close Codes 8.4. Context Close Codes
This document establishes a registry for HTTP context extension type
codes. The "HTTP Context Close Codes" registry governs a 62-bit
space. Registrations in this registry MUST include the following
fields:
Type: This document establishes a registry for HTTP context close codes.
The "HTTP Context Close Codes" registry governs a 62-bit space.
Registrations in this registry MUST include the following fields:
A name or label for the close code. Type: A name or label for the close code.
Value: The value of the CLOSE_CODE Context Extension Value field Value: The value of the Close Code field (see Section 4.4.3) is a
(see Section 5.1) is a 62bit integer. 62-bit integer.
Reference: An optional reference to a specification for the Reference: An optional reference to a specification for the
parameter. This field MAY be empty. parameter. This field MAY be empty.
Registrations follow the "First Come First Served" policy (see Registrations follow the "First Come First Served" policy (see
Section 4.4 of [IANA-POLICY]) where two registrations MUST NOT have Section 4.4 of [IANA-POLICY]) where two registrations MUST NOT have
the same Type nor Value. the same Type nor Value.
This registry initially contains the following entries: This registry initially contains the following entries:
+------------------------------+-------+---------------+ +====================+==========+===============+
| Context Close Code | Value | Specification | | Context Close Code | Value | Specification |
+------------------------------+-------+---------------+ +====================+==========+===============+
| NO_ERROR | 0x00 | This Document | | NO_ERROR | 0xff78a0 | This Document |
+------------------------------+-------+---------------+ +--------------------+----------+---------------+
| DENIED | 0x01 | This Document | | UNKNOWN_FORMAT | 0xff78a1 | This Document |
+------------------------------+-------+---------------+ +--------------------+----------+---------------+
| RESOURCE_LIMIT | 0x02 | This Document | | DENIED | 0xff78a2 | This Document |
+------------------------------+-------+---------------+ +--------------------+----------+---------------+
| RESOURCE_LIMIT | 0xff78a3 | This Document |
+--------------------+----------+---------------+
Table 3: Initial Context Close Code Registry
Entries
Context close codes with a value of the form 41 * N + 19 for integer Context close codes with a value of the form 41 * N + 19 for integer
values of N are reserved to exercise the requirement that unknown values of N are reserved to exercise the requirement that unknown
context close codes be treated as NO_ERROR. These values MUST NOT be context close codes be treated as NO_ERROR. These values MUST NOT be
assigned by IANA and MUST NOT appear in the listing of assigned assigned by IANA and MUST NOT appear in the listing of assigned
values. values.
11. Normative References 9. References
9.1. Normative References
[DGRAM] Pauly, T., Kinnear, E., and D. Schinazi, "An Unreliable [DGRAM] Pauly, T., Kinnear, E., and D. Schinazi, "An Unreliable
Datagram Extension to QUIC", Work in Progress, Internet- Datagram Extension to QUIC", Work in Progress, Internet-
Draft, draft-ietf-quic-datagram-03, 12 July 2021, Draft, draft-ietf-quic-datagram-06, 5 October 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-quic- <https://datatracker.ietf.org/doc/html/draft-ietf-quic-
datagram-03>. datagram-06>.
[H3] Bishop, M., "Hypertext Transfer Protocol Version 3 [H3] Bishop, M., "Hypertext Transfer Protocol Version 3
(HTTP/3)", Work in Progress, Internet-Draft, draft-ietf- (HTTP/3)", Work in Progress, Internet-Draft, draft-ietf-
quic-http-34, 2 February 2021, quic-http-34, 2 February 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-quic- <https://datatracker.ietf.org/doc/html/draft-ietf-quic-
http-34>. http-34>.
[IANA-POLICY] [IANA-POLICY]
Cotton, M., Leiba, B., and T. Narten, "Guidelines for Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26, Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017, RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/rfc/rfc8126>. <https://www.rfc-editor.org/rfc/rfc8126>.
[QUIC] Iyengar, J. and M. Thomson, "QUIC: A UDP-Based Multiplexed [QUIC] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
and Secure Transport", Work in Progress, Internet-Draft, Multiplexed and Secure Transport", RFC 9000,
draft-ietf-quic-transport-34, 14 January 2021, DOI 10.17487/RFC9000, May 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-quic- <https://www.rfc-editor.org/rfc/rfc9000>.
transport-34>.
[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,
<https://www.rfc-editor.org/rfc/rfc2119>. <https://www.rfc-editor.org/rfc/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>. May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
9.2. Informative References
[PRIORITY] Oku, K. and L. Pardue, "Extensible Prioritization Scheme
for HTTP", Work in Progress, Internet-Draft, draft-ietf-
httpbis-priority-06, 30 September 2021,
<https://datatracker.ietf.org/doc/html/draft-ietf-httpbis-
priority-06>.
[RFC8899] 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>.
Appendix A. Examples Appendix A. Examples
A.1. CONNECT-UDP A.1. CONNECT-UDP
Client Server Client Server
STREAM(44): HEADERS --------> STREAM(44): HEADERS -------->
:method = CONNECT-UDP :method = CONNECT-UDP
:scheme = https :scheme = https
:path = / :path = /
:authority = target.example.org:443 :authority = target.example.org:443
STREAM(44): CAPSULE --------> STREAM(44): DATA -------->
Capsule Type = REGISTER_DATAGRAM_CONTEXT Capsule Type = REGISTER_DATAGRAM_CONTEXT
Context ID = 0 Context ID = 0
Context Extension = {} Datagram Format Type = UDP_PAYLOAD
Datagram Format Additional Data = ""
DATAGRAM --------> DATAGRAM -------->
Quarter Stream ID = 11 Quarter Stream ID = 11
Context ID = 0 Context ID = 0
Payload = Encapsulated UDP Payload Payload = Encapsulated UDP Payload
<-------- STREAM(44): HEADERS <-------- STREAM(44): HEADERS
:status = 200 :status = 200
/* Wait for target server to respond to UDP packet. */ /* Wait for target server to respond to UDP packet. */
skipping to change at page 20, line 12 skipping to change at page 22, line 12
A.2. CONNECT-UDP with Timestamp Extension A.2. CONNECT-UDP with Timestamp Extension
Client Server Client Server
STREAM(44): HEADERS --------> STREAM(44): HEADERS -------->
:method = CONNECT-UDP :method = CONNECT-UDP
:scheme = https :scheme = https
:path = / :path = /
:authority = target.example.org:443 :authority = target.example.org:443
STREAM(44): CAPSULE --------> STREAM(44): DATA -------->
Capsule Type = REGISTER_DATAGRAM_CONTEXT Capsule Type = REGISTER_DATAGRAM_CONTEXT
Context ID = 0 Context ID = 0
Context Extension = {} Datagram Format Type = UDP_PAYLOAD
Datagram Format Additional Data = ""
DATAGRAM --------> DATAGRAM -------->
Quarter Stream ID = 11 Quarter Stream ID = 11
Context ID = 0 Context ID = 0
Payload = Encapsulated UDP Payload Payload = Encapsulated UDP Payload
<-------- STREAM(44): HEADERS <-------- STREAM(44): HEADERS
:status = 200 :status = 200
/* Wait for target server to respond to UDP packet. */ /* Wait for target server to respond to UDP packet. */
<-------- DATAGRAM <-------- DATAGRAM
Quarter Stream ID = 11 Quarter Stream ID = 11
Context ID = 0 Context ID = 0
Payload = Encapsulated UDP Payload Payload = Encapsulated UDP Payload
STREAM(44): CAPSULE --------> STREAM(44): DATA -------->
Capsule Type = REGISTER_DATAGRAM_CONTEXT Capsule Type = REGISTER_DATAGRAM_CONTEXT
Context ID = 2 Context ID = 2
Context Extension = {TIMESTAMP=""} Datagram Format Type = UDP_PAYLOAD_WITH_TIMESTAMP
Datagram Format Additional Data = ""
DATAGRAM --------> DATAGRAM -------->
Quarter Stream ID = 11 Quarter Stream ID = 11
Context ID = 2 Context ID = 2
Payload = Encapsulated UDP Payload With Timestamp Payload = Encapsulated UDP Payload With Timestamp
A.3. CONNECT-IP with IP compression A.3. CONNECT-IP with IP compression
Client Server Client Server
STREAM(44): HEADERS --------> STREAM(44): HEADERS -------->
:method = CONNECT-IP :method = CONNECT-IP
:scheme = https :scheme = https
:path = / :path = /
:authority = proxy.example.org:443 :authority = proxy.example.org:443
<-------- STREAM(44): HEADERS <-------- STREAM(44): HEADERS
:status = 200 :status = 200
/* Exchange CONNECT-IP configuration information. */ /* Exchange CONNECT-IP configuration information. */
STREAM(44): CAPSULE --------> STREAM(44): DATA -------->
Capsule Type = REGISTER_DATAGRAM_CONTEXT Capsule Type = REGISTER_DATAGRAM_CONTEXT
Context ID = 0 Context ID = 0
Context Extension = {} Datagram Format Type = IP_PACKET
Datagram Format Additional Data = ""
DATAGRAM --------> DATAGRAM -------->
Quarter Stream ID = 11 Quarter Stream ID = 11
Context ID = 0 Context ID = 0
Payload = Encapsulated IP Packet Payload = Encapsulated IP Packet
/* Endpoint happily exchange encapsulated IP packets */ /* Endpoint happily exchange encapsulated IP packets */
/* using Quarter Stream ID 11 and Context ID 0. */ /* using Quarter Stream ID 11 and Context ID 0. */
DATAGRAM --------> DATAGRAM -------->
Quarter Stream ID = 11 Quarter Stream ID = 11
Context ID = 0 Context ID = 0
Payload = Encapsulated IP Packet Payload = Encapsulated IP Packet
/* After performing some analysis on traffic patterns, */ /* After performing some analysis on traffic patterns, */
/* the client decides it wants to compress a 5-tuple. */ /* the client decides it wants to compress a 2-tuple. */
STREAM(44): CAPSULE --------> STREAM(44): DATA -------->
Capsule Type = REGISTER_DATAGRAM_CONTEXT Capsule Type = REGISTER_DATAGRAM_CONTEXT
Context ID = 2 Context ID = 2
Context Extension = {IP_COMPRESSION=tcp,192.0.2.6:9876,192.0.2.7:443} Datagram Format Type = COMPRESSED_IP_PACKET
Datagram Format Additional Data = "192.0.2.6,192.0.2.7"
DATAGRAM --------> DATAGRAM -------->
Quarter Stream ID = 11 Quarter Stream ID = 11
Context ID = 2 Context ID = 2
Payload = Compressed IP Packet Payload = Compressed IP Packet
A.4. WebTransport A.4. WebTransport
Client Server Client Server
STREAM(44): HEADERS --------> STREAM(44): HEADERS -------->
:method = CONNECT :method = CONNECT
:scheme = https :scheme = https
:method = webtransport :method = webtransport
:path = /hello :path = /hello
:authority = webtransport.example.org:443 :authority = webtransport.example.org:443
Origin = https://www.example.org:443 Origin = https://www.example.org:443
skipping to change at page 22, line 14 skipping to change at page 24, line 17
Client Server Client Server
STREAM(44): HEADERS --------> STREAM(44): HEADERS -------->
:method = CONNECT :method = CONNECT
:scheme = https :scheme = https
:method = webtransport :method = webtransport
:path = /hello :path = /hello
:authority = webtransport.example.org:443 :authority = webtransport.example.org:443
Origin = https://www.example.org:443 Origin = https://www.example.org:443
STREAM(44): CAPSULE --------> STREAM(44): DATA -------->
Capsule Type = REGISTER_DATAGRAM_NO_CONTEXT Capsule Type = REGISTER_DATAGRAM_NO_CONTEXT
Context Extension = {} Datagram Format Type = WEBTRANSPORT_DATAGRAM
Datagram Format Additional Data = ""
<-------- STREAM(44): HEADERS <-------- STREAM(44): HEADERS
:status = 200 :status = 200
/* Both endpoints can now send WebTransport datagrams. */ /* Both endpoints can now send WebTransport datagrams. */
Acknowledgments Acknowledgments
The DATAGRAM context identifier was previously part of the DATAGRAM The DATAGRAM context identifier was previously part of the DATAGRAM
frame definition itself, the authors would like to acknowledge the frame definition itself, the authors would like to acknowledge the
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