UDP通信的问题

问题描述：

       用UDP通信的时候有这个一个问题，假设有A,B两个进程，B向先A发消息，A收到消息以后，开2个线程，一个向B发消息，一个从B收消息，此时如果关掉B进程，A的接收线程就会不阻塞，错误码为10054。

原因：

看了很多资料，原来是winsock的bug，具体原因是：http://support.microsoft.com/kb/263823/

If sending a datagram using the sendto function results in an "ICMP port unreachable" response and the select function is set for readfds, the program returns 1 and the subsequent call to the recvfrom function does not work with a WSAECONNRESET (10054) error response. In Microsoft Windows NT 4.0, this situation causes the select function to block or time out.

解决：

A进程在创建SOCKET后，加入如下的代码：

DWORD dwBytesReturned = 0;
BOOL bNewBehavior = FALSE;
DWORD status;

#define SIO_UDP_CONNRESET _WSAIOW(IOC_VENDOR,12)
// disable  new behavior using
// IOCTL: SIO_UDP_CONNRESET
status = WSAIoctl(m_ClientSocket, SIO_UDP_CONNRESET,
      &bNewBehavior, sizeof(bNewBehavior),
      NULL, 0, &dwBytesReturned,
      NULL, NULL);

if (SOCKET_ERROR == status)
{
 DWORD dwErr = WSAGetLastError();
 if (WSAEWOULDBLOCK == dwErr)
 {
  // nothing to do
  return(FALSE);
 }
 else
 {
  printf("WSAIoctl(SIO_UDP_CONNRESET) Error: %d\\n", dwErr);
  return(FALSE);
 }
}