Adding the rest of WebTransport into Kestrel

[Daniel-Genkin-MS-2]

This is step two in my implementation of WebTransport support in Kestrel. This PR makes WebTransport functional and will provide a basic API for using it. Step three will be integration tests and maybe adding more features.

Goals of the PR

This PR builds upon my previous one (#41877 ) to add an API that interfaces with the existing Http3 layer in Kestrel and allows the application layer to:

• Receive a WebTransport session
• Open and receive/accept streams
• Send and Receive data over the streams
• Add some unit tests to support the new functionality
• Add a new sample app to show how to use WebTransport in Kestrel

Non-Goals of this PR

• Datagrams (hopefully will be added in some future PRs but it will require substantial amounts of work)
• Integration/Functional tests (these will be added in a follow up PR. The testing infrastructure is not setup yet, so it will add significant scope to this PR if it were to be done here)

Non-goals are tracked in #42788

Inadvertent results of the PR

#42097 (comment)

How to use:

C#: https://github.com/dotnet/aspnetcore/blob/c5e66c255c0254a9be191ee53031cec6b79def48/docs/WebTransport.md
JS: #42097 (comment)

OR

Use the interactive sample called WebTransportInteractiveSample in src\Middleware\WebTransport\samples\WebTransportInteractiveSampleApp

Contributes to: #39583

[Daniel-Genkin-MS-2]

Start a webtransport connection

1. Start the WebTransportSampleApp
2. Go to file:///C:/users/ in edge or chrome (or some other local directory to avoid CORS errors)
3. Open devtools and execute commands

Supported JS client operations

1. Create a webtransport connection

let CERTIFICATE = ""; // TODO UPDATE THIS to the certificate hash that the sample app prints out

let encoder = new TextEncoder('utf-8');

let transport = new WebTransport("https://127.0.0.1:5007", {
    serverCertificateHashes:[
      {
            algorithm: "sha-256",
            value: Uint8Array.from(atob(CERTIFICATE), c => c.charCodeAt(0))
        }]
    })

await transport.ready;

2. Create a unidirectional stream and send data

const stream1 = await transport.createUnidirectionalStream();
const writer1 = stream1.getWriter();
writer1.write(new Uint8Array([65, 66, 67, 68, 69, 70, 71, 72, 73, 74]));

3. Create a bidirectional stream and send data

const stream2 = await transport.createBidirectionalStream();
const writer2 = stream2.writable.getWriter();
writer2.write(new Uint8Array([66, 67, 68, 69, 70, 71, 72, 73, 74, 75]));

4. Accept a unidirectional stream from the server

const streamReader = await transport.incomingUnidirectionalStreams.getReader();
const streamResult = await reader.read();
const stream = streamResult.value;

5. Read from a unidirectional stream

const reader1 = stream1.getReader();
await reader1.read();

6. Read from a bidirectional stream

const reader2 = stream2.readable.getReader();
await reader2.read();

[ghost]

@Daniel-Genkin-MS-2, this change will be considered for inclusion in the blog post for the release it'll ship in. Nice work!

Please ensure that the original comment in this thread contains a clear explanation of what the change does, why it's important (what problem does it solve?), and, if relevant, include things like code samples and/or performance numbers.

This content may not be exactly what goes into the blog post, but it will help the team putting together the announcement.

Thanks!

[halter73]

I still need to try out the samples, but don't wait on me.

[Tratcher]

Just a few minor comments left. Great job!

[Pilchie]

Yay!