[dart:io] Ignore server http upgrade request unless status code is right

sdk/lib/io/http_parser.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart.io;
 
 // Global constants.
 class _Const {
   // Bytes for "HTTP".
   static const HTTP = const [72, 84, 84, 80];
@@ skipping 646 matching lines @@
             _state = _State.HEADER_VALUE_START;
           } else {
             String headerField = new String.fromCharCodes(_headerField);
             String headerValue = new String.fromCharCodes(_headerValue);
             if (headerField == "transfer-encoding" &&
                 _caseInsensitiveCompare("chunked".codeUnits, _headerValue)) {
               _chunked = true;
             }
             if (headerField == "connection") {
               List<String> tokens = _tokenizeFieldValue(headerValue);
+              final bool isResponse = _messageType == _MessageType.RESPONSE;
+              final bool isUpgradeCode =
+                  _statusCode == HttpStatus.UPGRADE_REQUIRED ||
+                      _statusCode == HttpStatus.SWITCHING_PROTOCOLS;

[siva, 2017/08/07 21:30:19]

Not sure about Dart coding standards but would make sense to add parens around
the conditions for better readability
(_statusCode == ...) || (_statusCode == ...)

[zra, 2017/08/07 22:09:04]

Couldn't find any guidance in the style guide, but I added the parens for
grouping.

               for (int i = 0; i < tokens.length; i++) {
-                if (_caseInsensitiveCompare(
-                    "upgrade".codeUnits, tokens[i].codeUnits)) {
+                final bool isUpgrade = _caseInsensitiveCompare(
+                    "upgrade".codeUnits, tokens[i].codeUnits);
+                if ((isUpgrade && !isResponse) ||
+                    (isUpgrade && isResponse && isUpgradeCode)) {
                   _connectionUpgrade = true;
                 }
                 _headers._add(headerField, tokens[i]);
               }
             } else {
               _headers._add(headerField, headerValue);
             }
             _headerField.clear();
             _headerValue.clear();
 
@@ skipping 367 matching lines @@
     }
   }
 
   void _reportError(error, [stackTrace]) {
     if (_socketSubscription != null) _socketSubscription.cancel();
     _state = _State.FAILURE;
     _controller.addError(error, stackTrace);
     _controller.close();
   }
 }