Avoiding a double disconnect scenario, and DFATALs on server.

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 1600 matching lines @@
 
 void QuicConnection::SendConnectionClose(QuicErrorCode error) {
   SendConnectionCloseWithDetails(error, string());
 }
 
 void QuicConnection::SendConnectionCloseWithDetails(QuicErrorCode error,
                                                     const string& details) {
   // If we're write blocked, WritePacket() will not send, but will capture the
   // serialized packet.
   SendConnectionClosePacket(error, details);
-  CloseConnection(error, false);
+  if (connected_) {
+    // It's possible that while sending the connection close packet, we get a
+    // socket error and disconnect right then and there.  Avoid a double
+    // disconnect in that case.
+    CloseConnection(error, false);
+  }
 }
 
 void QuicConnection::SendConnectionClosePacket(QuicErrorCode error,
                                                const string& details) {
   DVLOG(1) << ENDPOINT << "Force closing " << connection_id()
            << " with error " << QuicUtils::ErrorToString(error)
            << " (" << error << ") " << details;
   ScopedPacketBundler ack_bundler(this, SEND_ACK);
   QuicConnectionCloseFrame* frame = new QuicConnectionCloseFrame();
   frame->error_code = error;
@@ skipping 170 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