Don't allow half-open TLS connections

[pimterry]

I'm trying to detect clients rejecting my HTTPS certificate, using httpolyglot.

With the current httpolyglot server, if a client cleanly closes a TLS connection after the server hello (i.e. when it decides it doesn't like the certificate), the current httpolyglot never fires a tlsClientError event, whilst https.Server does.

I've hit this because that's the behaviour of Node 12 TLS clients - they cleanly close connections at this point (in Node 10, the handshake completes, secureConnection fires, and then the client closes the connection without sending any data - that works fine).

The below test demonstrates the issue. I haven't committed it, because it only works with Node 12, but hopefully it shows what I'm talking about.

var fs = require('fs');
var https = require('https');
var assert = require('assert');

var common = require(__dirname + '/common');
var httpolyglot = require(__dirname + '/../lib/index');

var srv = httpolyglot.createServer({
  key: fs.readFileSync(__dirname + '/fixtures/server.key'),
  cert: fs.readFileSync(__dirname + '/fixtures/server.crt')
}, function() {
  assert(false, 'Request handler should not be called');
})

srv.listen(0, '127.0.0.1', common.mustCall(function() {
  var port = this.address().port;

  var request = https.get({
    host: '127.0.0.1',
    port: port,
    rejectUnauthorized: true
  });
  request.on('error', common.mustCall(function (error) {
    assert(
      /certificate/.test(error.message),
      'Request should be rejected with a certificate error'
    );
  }));
}));

// Without this change, this is never called:
srv.on('tlsClientError', common.mustCall(function() {
  srv.close();
}));

This appears to happen because httpolyglot allows half-open TLS connections, whilst https.Server does not. As far as I can tell half-open connections are only allowed by default on http.Server, so I've changed the code here to disable it on sockets once we know that they are definitely TLS.

With this change, the above test passes.

[pimterry]

Just wanted to highlight that this is different to #10, in that this change only disables half-open sockets for TLS connections, and leaves plain HTTP untouched.

Afaict your comment there is only half correct, and HTTPS servers don't actually set allowHalfOpen to true. Mainly because the above test passes immediately if you use https.Server instead of httpolyglot, but also based on a skim of https://github.com/nodejs/node/blob/master/lib/https.js, which doesn't do that or call the http.Server constructor that would do so either.

[r0mflip]

+1

[pimterry]

@mscdex anything I can do to help get this merged? It's a clear difference in behaviour between httpolyglot & https.Server, and it'd be really useful to have it fixed so that tlsClientError events work correctly, and to make the behaviour generally more consistent.