http: do not emit `upgrade` on advertisement

Do not emit `upgrade` if the server is just advertising its protocols
support as per RFC 7230 Section 6.7.

    A server MAY send an Upgrade header field in any other response
    to advertise that it implements support for upgrading to the
    listed protocols, in order of descending preference, when
    appropriate for a future request.

Fix: https://github.com/nodejs/node/issues/4334
PR-URL: https://github.com/nodejs/node/pull/4337
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

lib/_http_client.js

@@ -471,6 +471,7 @@ function tickOnSocket(req, socket) {
   parser.reinitialize(HTTPParser.RESPONSE);
   parser.socket = socket;
   parser.incoming = null;
+  parser.outgoing = req;
   req.parser = parser;
 
   socket.parser = parser;

lib/_http_common.js

@@ -78,6 +78,20 @@ function parserOnHeadersComplete(versionMajor, versionMinor, headers, method,
     parser.incoming.statusMessage = statusMessage;
   }
 
+  // The client made non-upgrade request, and server is just advertising
+  // supported protocols.
+  //
+  // See RFC7230 Section 6.7
+  //
+  // NOTE: RegExp below matches `upgrade` in `Connection: abc, upgrade, def`
+  // header.
+  if (upgrade &&
+      parser.outgoing !== null &&
+      (parser.outgoing._headers.upgrade === undefined ||
+       !/(^|\W)upgrade(\W|$)/i.test(parser.outgoing._headers.connection))) {
+    upgrade = false;
+  }
+
   parser.incoming.upgrade = upgrade;
 
   var skipBody = false; // response to HEAD or CONNECT
@@ -143,6 +157,10 @@ var parsers = new FreeList('parsers', 1000, function() {
   parser._url = '';
   parser._consumed = false;
 
+  parser.socket = null;
+  parser.incoming = null;
+  parser.outgoing = null;
+
   // Only called in the slow case where slow means
   // that the request headers were either fragmented
   // across multiple TCP packets or too large to be
@@ -177,6 +195,7 @@ function freeParser(parser, req, socket) {
       parser.socket.parser = null;
     parser.socket = null;
     parser.incoming = null;
+    parser.outgoing = null;
     parser[kOnExecute] = null;
     if (parsers.free(parser) === false)
       parser.close();

test/parallel/test-http-upgrade-advertise.js

@@ -0,0 +1,54 @@
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+const http = require('http');
+
+const tests = [
+  { headers: {}, expected: 'regular' },
+  { headers: { upgrade: 'h2c' }, expected: 'regular' },
+  { headers: { connection: 'upgrade' }, expected: 'regular' },
+  { headers: { connection: 'upgrade', upgrade: 'h2c' }, expected: 'upgrade' }
+];
+
+function fire() {
+  if (tests.length === 0)
+    return server.close();
+
+  const test = tests.shift();
+
+  const done = common.mustCall(function done(result) {
+    assert.equal(result, test.expected);
+
+    fire();
+  });
+
+  const req = http.request({
+    port: common.PORT,
+    path: '/',
+    headers: test.headers
+  }, function onResponse(res) {
+    res.resume();
+    done('regular');
+  });
+
+  req.on('upgrade', function onUpgrade(res, socket) {
+    socket.destroy();
+    done('upgrade');
+  });
+
+  req.end();
+}
+
+const server = http.createServer(function(req, res) {
+  res.writeHead(200, {
+    Connection: 'upgrade, keep-alive',
+    Upgrade: 'h2c'
+  });
+  res.end('hello world');
+}).on('upgrade', function(req, socket) {
+  socket.end('HTTP/1.1 101 Switching protocols\r\n' +
+             'Connection: upgrade\r\n' +
+             'Upgrade: h2c\r\n\r\n' +
+             'ohai');
+}).listen(common.PORT, fire);

test/parallel/test-http-upgrade-agent.js

@@ -36,6 +36,7 @@ srv.listen(common.PORT, '127.0.0.1', function() {
     port: common.PORT,
     host: '127.0.0.1',
     headers: {
+      'connection': 'upgrade',
       'upgrade': 'websocket'
     }
   };

test/parallel/test-http-upgrade-client.js

@@ -32,7 +32,13 @@ var gotUpgrade = false;
 
 srv.listen(common.PORT, '127.0.0.1', function() {
 
-  var req = http.get({ port: common.PORT });
+  var req = http.get({
+    port: common.PORT,
+    headers: {
+      connection: 'upgrade',
+      upgrade: 'websocket'
+    }
+  });
   req.on('upgrade', function(res, socket, upgradeHead) {
     var recvData = upgradeHead;
     socket.on('data', function(d) {