Endless get request starting 0.6.7+1 version

[sestegra]

In my application, when a OPTIONS request is done, the server didn't answer (in the network console, the request is pending for 3 minutes).
The issue occurs on Dartium, Chrome, Safari, Firefox.

The same case is running well with previous Shelf versions.

[nex3]

Can you provide a pure-Dart reproduction with a Dart HTTP client?

[sestegra]

See following example that works on shelf 0.6.7 and doesn't work with next version

import 'dart:async';
import 'package:shelf/shelf.dart' as shelf;
import 'package:shelf/shelf_io.dart' as io;

Future<Null> main(List<String> args) async {
  var handler = const shelf.Pipeline()
      .addMiddleware(shelf.logRequests())
      .addHandler(echoRequest);

  var server = await io.serve(handler, '127.0.0.1', 8080);
  print('Serving at http://${server.address.host}:${server.port}');
}

shelf.Response echoRequest(shelf.Request request) {
  return new shelf.Response.ok(null);
}

Use following command to simulate the request, the command doesn't complete.

$ curl -v http://127.0.0.1:8080/
*   Trying 127.0.0.1...
* Connected to 127.0.0.1 (127.0.0.1) port 8080 (#0)
> GET / HTTP/1.1
> Host: 127.0.0.1:8080
> User-Agent: curl/7.43.0
> Accept: */*
> 
< HTTP/1.1 200 OK
< date: Sat, 19 Nov 2016 10:05:50 GMT
< x-frame-options: SAMEORIGIN
< content-type: text/plain; charset=utf-8
< x-xss-protection: 1; mode=block
< x-content-type-options: nosniff
< server: dart:io with Shelf
* no chunk, no close, no size. Assume close to signal end
< 

Compared to results from 0.6.7 version, the content-length: 0 part is missing in the response.

[nex3]

This turns out to be pretty complex. Some of the assumptions I was making about HTTP header validity turn out to have been wrong, but fixing them will involve coming up with a consistent model for how the Content-Length and Transfer-Encoding headers interact with one another and with adapters, which is non-trivial, especially in the face of a number of dart:io issues (dart-lang/sdk#27885 and dart-lang/sdk#27886 in particular).

[Tomucha]

I did run into it too. I'm using shelf_cors middleware, which does this:

 Response handleOptionsRequest(Request request) {
     if (request.method == 'OPTIONS') {
         return new Response.ok(null, headers: CORS_HEADERS);
         ...

Quick fix/workaround for anyone out there is to return something:

         return new Response.ok("OK", headers: CORS_HEADERS);

[nex3]

I should have a fixed version of shelf released in the next couple days.