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Integrate with fetch #697

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ab09da5
Integrate with fetch
jan-ivar Oct 20, 2025
b5506d7
Fixes bikeshed errors
jan-ivar Oct 21, 2025
738cd63
s/process a response/process a WebTransport fetch response/
jan-ivar Oct 21, 2025
dcd86af
Anticipate fetch passing in |request| to obtain a WebTransport connec…
jan-ivar Oct 21, 2025
0d5b665
Fixes bikeshed errors
jan-ivar Oct 21, 2025
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105 changes: 62 additions & 43 deletions index.bs
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Original file line number Diff line number Diff line change
Expand Up @@ -853,6 +853,18 @@ A {{WebTransport}} object has the following internal slots.
<td><dfn>`[[Session]]`</dfn>
<td class="non-normative">A [=WebTransport session=] for this {{WebTransport}} object, or null.
</tr>
<tr>
<td><dfn>`[[NewConnection]]`</dfn>
<td class="non-normative">Either `"no"` or `"yes-and-dedicated"`.
</tr>
<tr>
<td><dfn>`[[RequireUnreliable]]`</dfn>
<td class="non-normative">A boolean indicating whether UDP is required.
</tr>
<tr>
<td><dfn>`[[ServerCertificateHashes]]`</dfn>
<td class="non-normative">A [=list=] of zero or more {{WebTransportHash}} objects.
</tr>
</table>

## Constructor ## {#webtransport-constructor}
Expand All @@ -861,18 +873,19 @@ A {{WebTransport}} object has the following internal slots.
When the {{WebTransport/constructor()}} constructor is invoked, the user
agent MUST run the following steps:
1. Let |baseURL| be [=this=]'s [=relevant settings object=]'s [=API base URL=].
1. Let |parsedURL| be the [=URL record=] resulting from [=URL parser|parsing=]
1. Let |url| be the [=URL record=] resulting from [=URL parser|parsing=]
{{WebTransport/constructor(url, options)/url}} with |baseURL|.
1. If |parsedURL| is a failure, [=throw=] a {{SyntaxError}} exception.
1. If |parsedURL| [=scheme=] is not `https`, [=throw=] a {{SyntaxError}} exception.
1. If |parsedURL| [=fragment=] is not null, [=throw=] a {{SyntaxError}} exception.
1. If |url| is a failure, [=throw=] a {{SyntaxError}} exception.
1. If |url| [=scheme=] is not `https`, [=throw=] a {{SyntaxError}} exception.
1. If |url| [=fragment=] is not null, [=throw=] a {{SyntaxError}} exception.
1. Let |allowPooling| be {{WebTransport/constructor(url, options)/options}}'s
{{WebTransportOptions/allowPooling}}.
1. Let |dedicated| be the negation of |allowPooling|.
1. Let |serverCertificateHashes| be {{WebTransport/constructor(url, options)/options}}'s
{{WebTransportOptions/serverCertificateHashes}} if it exists, and null otherwise.
1. If |dedicated| is false and |serverCertificateHashes| is non-null, then [=throw=] a
{{NotSupportedError}} exception.
1. Let |newConnection| be `"no"` if |dedicated| is false; otherwise `"yes-and-dedicated"`.
1. Let |requireUnreliable| be {{WebTransport/constructor(url, options)/options}}'s
{{WebTransportOptions/requireUnreliable}}.
1. Let |congestionControl| be {{WebTransport/constructor(url, options)/options}}'s
Expand Down Expand Up @@ -930,12 +943,18 @@ agent MUST run the following steps:
:: |datagrams|
: {{[[Session]]}}
:: null
: {{[[NewConnection]]}}
:: |newConnection|
: {{[[RequireUnreliable]]}}
:: |requireUnreliable|
: {{[[ServerCertificateHashes]]}}
:: |serverCertificateHashes|
1. Let |pullDatagramsAlgorithm| be an action that runs [=pullDatagrams=] with |transport|.

Note: Using 64kB buffers with datagrams is recommended because the effective
maximum WebTransport datagram frame size has an upper bound of the QUIC maximum datagram frame size
which is recommended to be 64kB (See [[!QUIC-DATAGRAM]] [Section 3](https://datatracker.ietf.org/doc/html/rfc9221#section-3)).
This will ensure the stream is not errored due to a datagram being larger than the buffer.
Note: Using 64kB buffers with datagrams is recommended because the effective
maximum WebTransport datagram frame size has an upper bound of the QUIC maximum datagram frame size
which is recommended to be 64kB (See [[!QUIC-DATAGRAM]] [Section 3](https://datatracker.ietf.org/doc/html/rfc9221#section-3)).
This will ensure the stream is not errored due to a datagram being larger than the buffer.

1. If |datagramsReadableMode| is `"bytes"`, [=ReadableStream/set up with byte reading support=]
|incomingDatagrams| with [=ReadableStream/set up with byte reading support/pullAlgorithm=] set
Expand All @@ -953,48 +972,45 @@ This will ensure the stream is not errored due to a datagram being larger than t
1. [=ReadableStream/Set up=] |transport|.{{[[IncomingUnidirectionalStreams]]}} with
[=ReadableStream/set up/pullAlgorithm=] set to |pullUnidirectionalStreamAlgorithm|, and
[=ReadableStream/set up/highWaterMark=] set to 0.
1. [=Initialize WebTransport over HTTP=] with |transport|, |parsedURL|, |dedicated|,
|requireUnreliable|, |congestionControl|, |protocols|, and |serverCertificateHashes|.
1. Let |client| be |transport|'s [=relevant settings object=].
1. Let |origin| be |client|'s [=environment settings object/origin=].
1. Let |request| be a new [=/request=] whose [=request/URL=] is |url|, [=request/client=] is
|client|, [=service-workers mode=] is "`none`",
[=request/referrer=] is "`no-referrer`", [=request/mode=] is "`webtransport`",
[=request/credentials mode=] is "`omit`", [=request/cache mode=] is "`no-store`",
[=request/policy container=] is |client|'s
[=environment settings object/policy container=], [=request/destination=] is "",
[=request/origin=] is |origin| and [=request/redirect mode=] is "error".
1. [=Fetch=] |request|, with [=useParallelQueue=] set to true, and [=processResponse=]
set to the following steps given a |response|:
1. [=Process a response=] with |response|, |origin|, |protocols|, and |congestionControl|.
1. Return |transport|.

</div>

<div algorithm>
To <dfn>initialize WebTransport over HTTP</dfn>, given a {{WebTransport}} object
<var>transport</var>, a [=URL record=] |url|, a boolean |dedicated|, a boolean
|requireUnreliable|, a {{WebTransportCongestionControl}} |congestionControl|,
a |protocols| array, and a
sequence&lt;{{WebTransportHash}}&gt; |serverCertificateHashes|, run these steps.
Note: The plan is for [=fetch=] to call into the below algorithm based off a
new "`webtransport`" [=request/mode=]. [#1808](https://github.com/whatwg/fetch/issues/1808).

1. Let |client| be |transport|'s [=relevant settings object=].
1. Let |origin| be |client|'s [=environment settings object/origin=].
1. Let |request| be a new [=/request=] whose [=request/URL=] is |url|, [=request/client=] is
|client|, [=request/policy container=] is |client|'s
[=environment settings object/policy container=], [=request/destination=] is an empty string,
[=request/origin=] is |origin| and [=request/redirect mode=] is "error".
1. Run <a>report Content Security Policy violations for |request|</a>.
1. If [=should request be blocked by Content Security Policy?=] with |request| returns
<b>"Blocked"</b>, or if |request| [=block bad port|should be blocked due to a bad port=]
returns <b>blocked</b>, then abort the remaining steps and [=queue a network task=] with |transport|
to run these steps:
1. If |transport|.{{[[State]]}} is `"closed"` or `"failed"`, then abort these steps.
1. Let |error| be a newly [=DOMException/created=] {{WebTransportError}} whose
{{WebTransportErrorOptions/source}} is `"session"`.
1. [=Cleanup=] |transport| with |error|.
1. Let |networkPartitionKey| be the result of [=determining the network partition key=] with
|transport|'s [=relevant settings object=].
1. Run the following steps [=in parallel=], but [=abort when=] |transport|.{{[[State]]}} becomes `"closed"` or `"failed"`:
1. Let |newConnection| be "`no`" if |dedicated| is false; otherwise "`yes-and-dedicated`".
1. Let |connection| be the result of [=obtain a connection|obtaining a connection=] with
|networkPartitionKey|, |url|, false, |newConnection|, and |requireUnreliable|. If the user agent
supports more than one congestion control algorithm, choose one appropriate for
|congestionControl| for sending of data on this |connection|. When obtaining a connection, if
<div algorithm>
To <dfn export>obtain a WebTransport connection</dfn>, given a [=network partition key=]
|networkPartitionKey|, and a [=URL record=] |url|, run these steps:
1. Let |transport| be the {{WebTransport}} object associated with this request.
1. Let |newConnection| be |transport|.{{[[NewConnection]]}}.
1. Let |requireUnreliable| be |transport|.{{[[RequireUnreliable]]}}.
1. Let |serverCertificateHashes| be the values in |transport|.{{[[ServerCertificateHashes]]}}.
1. Return the result of [=obtain a connection|obtaining a connection=] with
|networkPartitionKey|, |url|, false, |newConnection|, and |requireUnreliable|.
When obtaining a connection, if
|serverCertificateHashes| is specified, instead of using the default certificate verification
algorithm, consider the certificate valid if it meets the [=custom certificate
requirements=] and if [=verify a certificate hash|verifying the certificate hash=] against
|serverCertificateHashes| returns true. If either condition is not met, let |connection| be
failure.
1. If |connection| is failure, then abort the remaining steps and [=queue a network task=] with
|serverCertificateHashes| returns true. If either condition is not met, fail with a
[=network error=].
</div>

<div algorithm>
To <dfn>process a response</dfn>, given a |response|, |origin|, |protocols|, and |congestionControl|, run these steps:
1. If |response| is [=network error=], then abort the remaining steps and [=queue a network task=] with
|transport| to run these steps:
1. If |transport|.{{[[State]]}} is `"closed"` or `"failed"`, then abort these steps.
1. Let |error| be a newly [=DOMException/created=] {{WebTransportError}} whose
Expand All @@ -1006,6 +1022,7 @@ sequence&lt;{{WebTransportHash}}&gt; |serverCertificateHashes|, run these steps.
information that would normally be blocked by CORS. In same-origin contexts, it might
encourage applications to abuse the handshake as a vector for passing information.

1. Let |connection| be the underlying connection associated with |response|.
1. Wait for |connection| to receive the first SETTINGS frame, and let |settings| be a dictionary that
represents the SETTINGS frame.
1. If |settings| doesn't contain SETTINGS_ENABLE_WEBTRANPORT with a value of 1, or it doesn't
Expand All @@ -1026,6 +1043,8 @@ sequence&lt;{{WebTransportHash}}&gt; |serverCertificateHashes|, run these steps.
{{WebTransportErrorOptions/source}} is `"session"`.
1. [=Cleanup=] |transport| with |error|.
1. Let |session| be the established [=WebTransport session=].
1. If the user agent supports more than one congestion control algorithm, choose one
appropriate for |congestionControl| for sending of data on this |connection|.
1. [=Queue a network task=] with |transport| to run these steps:
1. Assert: [=this=]'s {{[[Datagrams]]}}'s {{[[OutgoingMaxDatagramSize]]}} is an integer.
1. If |transport|.{{[[State]]}} is not `"connecting"`:
Expand Down Expand Up @@ -1433,7 +1452,7 @@ run these steps:

## Context cleanup steps ## {#web-transport-context-cleanup-steps}

This specification defines <dfn>context cleanup steps</dfn> as the following steps, given
This specification defines <dfn export>context cleanup steps</dfn> as the following steps, given
{{WebTransport}} |transport|:

1. If |transport|.{{[[State]]}} is `"connected"`, then:
Expand Down