If an idle socket has received data unexpectedly, we...

net/base/tcp_client_socket_libevent.cc

 // Copyright (c) 2006-2008 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/base/tcp_client_socket.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <netdb.h>
 #include <sys/socket.h>
@@ skipping 143 matching lines @@
   char c;
   int rv = recv(socket_, &c, 1, MSG_PEEK);
   if (rv == 0)
     return false;
   if (rv == -1 && errno != EAGAIN && errno != EWOULDBLOCK)
     return false;
 
   return true;
 }
 
+bool TCPClientSocket::IsConnectedAndIdle() const {
+  if (socket_ == kInvalidSocket || waiting_connect_)
+    return false;
+
+  // Check if connection is alive and we haven't received any data
+  // unexpectedly.
+  char c;
+  int rv = recv(socket_, &c, 1, MSG_PEEK);
+  if (rv >= 0)
+    return false;
+  if (errno != EAGAIN && errno != EWOULDBLOCK)
+    return false;
+
+  return true;
+}
+
 int TCPClientSocket::Read(char* buf,
                           int buf_len,
                           CompletionCallback* callback) {
   DCHECK(socket_ != kInvalidSocket);
   DCHECK(!waiting_connect_);
   DCHECK(!callback_);
   // Synchronous operation not supported
   DCHECK(callback);
   DCHECK(buf_len > 0);
 
@@ skipping 179 matching lines @@
     DidCompleteWrite();
   }
 }
 
 int TCPClientSocket::GetPeerName(struct sockaddr *name, socklen_t *namelen) {
   return ::getpeername(socket_, name, namelen);
 }
 
 }  // namespace net