More informative error when connecting to unsupported HTTP/2 end-point

[Songkeys]

Bug Description

node:internal/process/promises:289
            triggerUncaughtException(err, true /* fromPromise */);
            ^

HTTPParserError: Expected HTTP/
    at Parser.execute (/Users/songkeys/GitHub/playground/node_modules/undici/lib/client.js:572:15)
    at Parser.readMore (/Users/songkeys/GitHub/playground/node_modules/undici/lib/client.js:516:12)
    at TLSSocket.onSocketReadable (/Users/songkeys/GitHub/playground/node_modules/undici/lib/client.js:940:10)
    at TLSSocket.emit (node:events:513:28)
    at emitReadable_ (node:internal/streams/readable:590:12)
    at process.processTicksAndRejections (node:internal/process/task_queues:81:21) {
  code: 'HPE_INVALID_CONSTANT',
  data: '\x00\x00\x18\x04\x00\x00\x00\x00\x00\x00\x01\x00\x00\x10\x00\x00\x03\x00\x00\x00\x01\x00\x05\x00\x00@\x00\x00\x06\x00\x00\x1F@'
}

Node.js v19.3.0

Reproducible By

import { request } from "undici";

request("https://api.push.apple.com");

Environment

Node.js v19.3.0

undici@5.21.0

Additional context

This error only occurs on this specific endpoint.

[targos]

The error is not very informative, but I think this is expected because that endpoint is HTTP/2, not HTTP/1.1

[Songkeys]

Oh I just realized the API is HTTP/2 and undici only supports HTTP/1.1 so far. You were right. The issue might be the uninformative error message then.

[mcollina]

Thanks for reporting! Would you like to send a Pull Request to address this issue? Remember to add unit tests.

[Songkeys]

@mcollina Yes. I'm interested. Give me some time :)

[Songkeys]

@mcollina This looks more tough than I thought.

I tried to compare the first chunk read from the socket with http2 preface:

const HTTP2_PREFACE = 'PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n';
const http2PrefaceBuffer = Buffer.from(HTTP2_PREFACE, 'utf8');
return chunk.slice(0, http2PrefaceBuffer.length).equals(http2PrefaceBuffer);

but the chunk doesn't seem to make any sense. Take the API response in this issue as an example, it's: "\x00\x00\x18\x04\x00\x00\x00\x00\x00\x00\x01\x00\x00\x10\x00\x00\x03\x00\x00\x00\x01\x00\x05\x00\x00@\x00\x00\x06\x00\x00\x1F@".

I also tried to use socket.alpnProtocol to tell if the server is h2. but it always returns false.

Any instruction?

---

edit: do we need to actually tell if the server is h2 or just tell user that the http parsing is wrong and the server might be http2 with just changing the error message in HTTPParserError?

[mcollina]

I think we can just mention that we expected HTTP/1.1 and we didn't get it (leaving to the reader to figure out what protocol was on the wire).