如何判断一个socket连接是否关闭？

[wangcn]

如何判断一个socket连接是否关闭？

[V九门提督V]

发心跳包
www.google.com
解决了别忘了告诉我………

[老夏Max]

LOOK

[Jazzlover]

struct tcp_keepalive inKeepAlive, outKeepAlive;
unsigned long ulInLen, ulOutLen, ulBytesReturn;
inKeepAlive.onoff = 1;
inKeepAlive.keepaliveinterval = 30000;
inKeepAlive.keepalivetime = 300000;
ulInLen = sizeof(tcp_keepalive);
ulOutLen = sizeof(tcp_keepalive);
ulBytesReturn = 0;
memset( &outKeepAlive, 0, sizeof(tcp_keepalive) );
if (WSAIoctl(sock, SIO_KEEPALIVE_VALS, (LPVOID)&inKeepAlive, ulInLen,
(LPVOID)&outKeepAlive, ulOutLen, &ulBytesReturn, NULL, NULL) == SOCKET_ERROR){ writelog("WSAIoctl(keep alive) failed. error code = " + WSAGetLastError()) ;
}

如果 socket 关闭你就会接到通知。
p.s. 我的程序是 IOCP 的，通知从 GetQueuedCompletionStatus() 返回中得到。估计要是用 select() 的话，也可以从 errorlist 中得到；

[cnlzx]

如果你要判断网络状况，可以发心跳包什么的，

如果是想判断下本机的那个SOCKET是不是有效的，可以select，最后的参数结构里都为0可以马上返回，看下select的返回值就可以啦