Function onWebTransportSession

packages/engine.io/lib/server.ts:530–636

(session: any)

  }

  public async onWebTransportSession(session: any) {
    if (this.middlewares.length > 0) {
      // middlewares expect an IncomingMessage argument, which cannot be created from the WebTransport session object
      // see also: https://github.com/fails-components/webtransport/issues/448
      debug(
        "closing session since WebTransport is not compatible with middlewares",
      );
      return session.close();
    }

    const timeout = setTimeout(() => {
      debug(
        "the client failed to establish a bidirectional stream in the given period",
      );
      session.close();
    }, this.opts.upgradeTimeout);

    const streamReader = session.incomingBidirectionalStreams.getReader();
    const result = await streamReader.read();

    if (result.done) {
      clearTimeout(timeout);
      debug("session is closed");
      return;
    }

    const stream = result.value;
    const transformStream = createPacketDecoderStream(
      this.opts.maxHttpBufferSize,
      "nodebuffer",
    );
    const reader = stream.readable.pipeThrough(transformStream).getReader();

    const closeSession = async () => {
      try {
        await reader.cancel();
      } catch (e) {
        debug(
          "error while canceling WebTransport stream reader: %s",
          e.message,
        );
      }
      reader.releaseLock();
      session.close();
    };

    // reading the first packet of the stream
    const { value, done } = await reader.read();
    clearTimeout(timeout);

    if (done) {
      debug("stream is closed");
      reader.releaseLock();
      return;
    }

    if (value.type !== "open") {
      debug("invalid WebTransport handshake");