Avoiding quic double-close bugs by detecting it at the connection.

net/quic/quic_connection.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/quic_connection.h"
 
 #include <string.h>
 #include <sys/types.h>
 #include <algorithm>
 #include <iterator>
@@ skipping 1597 matching lines @@
   ScopedPacketBundler ack_bundler(this, SEND_ACK);
   QuicConnectionCloseFrame* frame = new QuicConnectionCloseFrame();
   frame->error_code = error;
   frame->error_details = details;
   packet_generator_.AddControlFrame(QuicFrame(frame));
   Flush();
 }
 
 void QuicConnection::CloseConnection(QuicErrorCode error, bool from_peer) {
   DCHECK(connected_);
+  if (!connected_) {
+    return;
+  }
   connected_ = false;
   visitor_->OnConnectionClosed(error, from_peer);
   // Cancel the alarms so they don't trigger any action now that the
   // connection is closed.
   ack_alarm_->Cancel();
   resume_writes_alarm_->Cancel();
   retransmission_alarm_->Cancel();
   send_alarm_->Cancel();
   timeout_alarm_->Cancel();
 }
@@ skipping 149 matching lines @@
   // If we changed the generator's batch state, restore original batch state.
   if (!already_in_batch_mode_) {
     DVLOG(1) << "Leaving Batch Mode.";
     connection_->packet_generator_.FinishBatchOperations();
   }
   DCHECK_EQ(already_in_batch_mode_,
             connection_->packet_generator_.InBatchMode());
 }
 
 }  // namespace net