[转]windows下设置socket的connect超时

原文地址:http://www.cnblogs.com/BloodAndBone/archive/2012/05/22/2513338.html

变相的实现connect的超时，我要讲的就是这个方法，原理上是这样的：
1．建立socket
2．将该socket设置为非阻塞模式
3．调用connect()
4．使用select()检查该socket描述符是否可写（注意，是可写）
5．根据select()返回的结果判断connect()结果
6．将socket设置为阻塞模式（如果你的程序不需要用阻塞模式的，这步就省了，不过一般情况下都是用阻塞模式的，这样也容易管理）

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// widonws: 默认设置socket TCP client connect为阻塞模式 void TcpConnect(char* strIP, UINT nPort) {     struct sockaddr_in serverAddress;     SOCKET hSocket = NULL;       hSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);     if( hSocket==INVALID_SOCKET)     {         return;     }       memset(&serverAddress, 0, sizeof(serverAddress));         serverAddress.sin_family      = AF_INET;     serverAddress.sin_addr.s_addr = inet_addr(strIP);       serverAddress.sin_port        = htons((short)nPort);          int iTimeOut = 3000;     setsockopt(hSocket,SOL_SOCKET,SO_RCVTIMEO,(char*)&iTimeOut,sizeof(iTimeOut));     setsockopt(hSocket,SOL_SOCKET,SO_SNDTIMEO,(char*)&iTimeOut,sizeof(iTimeOut));          if( SOCKET_ERROR==connect(hSocket, (sockaddr*)&serverAddress, sizeof(serverAddress)) )     {                closesocket(hSocket);         DWORD gle = WSAGetLastError();           return;     }       char buff[] = "hello";     int sl=::send(hSocket,(char*)buff, sizeof(buff), 0);     if( sl<0 )     {         closesocket(hSocket);         return ;     }     closesocket(hSocket); }   // widonws: 设置socket TCP client connect非阻塞模式 void SockSelect(char* strIP, UINT nPort) {     SOCKET/*int*/ sockfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);     if(sockfd < 0)     {         return;     }     struct sockaddr_in serv_addr;       //以服务器地址填充结构serv_addr     serv_addr.sin_family = AF_INET;     serv_addr.sin_addr.s_addr = inet_addr(strIP);     serv_addr.sin_port = htons(nPort);     int error = -1;     int len = sizeof(int);     timeval tm;     fd_set set;     unsigned long ul = 1;     ioctlsocket(sockfd, FIONBIO, &ul); //设置为非阻塞模式     bool ret = false;     if( connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) == -1)     {         tm.tv_sec  = 3;         tm.tv_usec = 0;         FD_ZERO(&set);         FD_SET(sockfd, &set);         if( select(sockfd+1, NULL, &set, NULL, &tm) > 0)         {             getsockopt(sockfd, SOL_SOCKET, SO_ERROR, (char *)&error, /*(socklen_t *)*/&len);             if(error == 0)                 ret = true;             else                 ret = false;         }         else             ret = false;     }     else         ret = true;     ul = 0;     ioctlsocket(sockfd, FIONBIO, &ul); //设置为阻塞模式     if(!ret)     {         closesocket( sockfd );         fprintf(stderr , "Cannot Connect the server!/n");         return;     }       fprintf( stderr , "Connected!/n");       char buff[] = "hello";     int sl=::send(sockfd,(char*)buff, sizeof(buff), 0);       closesocket( sockfd ); }