1821566 - Can't send datagrams of exactly the maxDatagramSize in WebTransport

Status: NEW

(Core :: Networking: HTTP, defect, P2)

Description

[Randell Jesup [:jesup] (needinfo me)]

If I send 1200 byte datagrams, I get a closed on the WebTransport:

0:18.70 pid:1244701 2023-03-10 01:53:24.897007 UTC - [Child 1244961: DOM Worker]: D/WebTransport Sending Datagram, size = 1200
 0:18.70 pid:1244701 2023-03-10 01:53:24.897053 UTC - [Parent 1244701: Socket Thread]: D/WebTransport WebTransportParent sending datagram
 0:18.70 pid:1244701 2023-03-10 01:53:24.897056 UTC - [Parent 1244701: Socket Thread]: V/WebTransport Sending datagram 8, length 1200
 0:18.70 pid:1244701 2023-03-10 01:53:24.897058 UTC - [Parent 1244701: Socket Thread]: D/nsWebTransport Sending datagram id=8
 0:18.70 pid:1244701 2023-03-10 01:53:24.897062 UTC - [Parent 1244701: Socket Thread]: D/WebTransport Sent datagram id= 8
 0:18.70 pid:1244701 2023-03-10 01:53:24.897066 UTC - [Child 1244961: DOM Worker]: V/WebTransport NewBidirectionalStream()
 0:18.70 pid:1244701 2023-03-10 01:53:24.897070 UTC - [Child 1244961: DOM Worker]: D/WebTransport NotifyIncomingStream
 0:18.70 pid:1244701 2023-03-10 01:53:24.897073 UTC - [Child 1244961: DOM Worker]: D/WebTransport NotifyIncomingStream: 1 Bidirectional
 0:18.70 pid:1244701 2023-03-10 01:53:24.897098 UTC - [Child 1244961: DOM Worker]: D/WebTransport Datagram was sent
 0:18.70 pid:1244701 2023-03-10 01:53:24.897121 UTC - [Child 1244961: DOM Worker]: D/WebTransport Datagrams Pull waiting for a datagram
 0:18.70 pid:1244701 2023-03-10 01:53:24.897394 UTC - [Parent 1244701: Socket Thread]: D/nsWebTransport WebTransportSessionProxy::OnSessionClosed 7f57f228f340 mState=3 mStopRequestCalled=1
 0:18.70 pid:1244701 2023-03-10 01:53:24.897399 UTC - [Parent 1244701: Socket Thread]: D/nsWebTransport WebTransportSessionProxy::ChangeState 3 -> 4 [this=7f57f228f340]
 0:18.70 pid:1244701 2023-03-10 01:53:24.897402 UTC - [Parent 1244701: Socket Thread]: D/nsWebTransport WebTransportSessionProxy::ChangeState 4 -> 6 [this=7f57f228f340]

Comment 1

[Randell Jesup [:jesup] (needinfo me)]

Added this test to datagrams:

promise_test(async t => {
  // Establish a WebTransport session.
  const wt = new WebTransport(webtransport_url('echo.py'));
  await wt.ready;
  wt.closed.then(() => dump("******* closed\n"));

  const writer = wt.datagrams.writable.getWriter();
  const reader = wt.datagrams.readable.getReader();

  // Write and read max-size datagram.
  await writer.write(new Uint8Array(wt.datagrams.maxDatagramSize));
  const { value: token, done } = await reader.read();
  dump("*** length = " + token.length + " : " + wt.datagrams.maxDatagramSize + "\n");
  assert_equals(token.length, wt.datagrams.maxDatagramSize);
  dump("*** pass\n");
}, 'Transfer max-size datagrams');

Comment 2

[Randell Jesup [:jesup] (needinfo me)]

The real issue is that the pref for datagram size isn't the payload, it's the raw datagram data packet size; we need to get the actual max payload size from the stack and feed that over to content.