Unix(Linux) C++ 下支持timeout的connect()的实现例子

java 的connect有timeout这个功能，C++的connect反而没有？ 网查得到了两个实现的版本如下：

 

支持timeout的connect() / Connect with timeout

Code:

 

 void connect_w_to(void) { int res; struct sockaddr_in addr; long arg; fd_set myset; struct timeval tv; int valopt; socklen_t lon; // Create socket soc = socket(AF_INET, SOCK_STREAM, 0); if (soc < 0) { fprintf(stderr, "Error creating socket (%d %s)/n", errno, strerror(errno)); exit(0); } addr.sin_family = AF_INET; addr.sin_port = htons(2000); addr.sin_addr.s_addr = inet_addr("192.168.0.1"); // Set non-blocking if( (arg = fcntl(soc, F_GETFL, NULL)) < 0) { fprintf(stderr, "Error fcntl(..., F_GETFL) (%s)/n", strerror(errno)); exit(0); } arg |= O_NONBLOCK; if( fcntl(soc, F_SETFL, arg) < 0) { fprintf(stderr, "Error fcntl(..., F_SETFL) (%s)/n", strerror(errno)); exit(0); } // Trying to connect with timeout res = connect(soc, (struct sockaddr *)&addr, sizeof(addr)); if (res < 0) { if (errno == EINPROGRESS) { fprintf(stderr, "EINPROGRESS in connect() - selecting/n"); do { tv.tv_sec = 5 //overtime; tv.tv_usec = 0; FD_ZERO(&myset); FD_SET(soc, &myset); res = select(soc+1, NULL, &myset, NULL, &tv); if (res < 0 && errno != EINTR) { fprintf(stderr, "Error connecting %d - %s/n", errno, strerror(errno)); exit(0); } else if (res > 0) { // Socket selected for write lon = sizeof(int); if (getsockopt(soc, SOL_SOCKET, SO_ERROR, (void*)(&valopt), &lon) < 0) { fprintf(stderr, "Error in getsockopt() %d - %s/n", errno, strerror(errno)); exit(0); } // Check the value returned... if (valopt) { fprintf(stderr, "Error in delayed connection() %d - %s/n", valopt, strerror(valopt) ); exit(0); } break; } else { fprintf(stderr, "Timeout in select() - Cancelling!/n"); exit(0); } } while (1); } else { fprintf(stderr, "Error connecting %d - %s/n", errno, strerror(errno)); exit(0); } } // Set to blocking mode again... if( (arg = fcntl(soc, F_GETFL, NULL)) < 0) { fprintf(stderr, "Error fcntl(..., F_GETFL) (%s)/n", strerror(errno)); exit(0); } arg &= (~O_NONBLOCK); if( fcntl(soc, F_SETFL, arg) < 0) { fprintf(stderr, "Error fcntl(..., F_SETFL) (%s)/n", strerror(errno)); exit(0); } // I hope that is all }

 

简化版本Code:

void connect_w_to(void) { int res, valopt; struct sockaddr_in addr; long arg; fd_set myset; struct timeval tv; socklen_t lon; // Create socket soc = socket(AF_INET, SOCK_STREAM, 0); // Set non-blocking arg = fcntl(soc, F_GETFL, NULL); arg |= O_NONBLOCK; fcntl(soc, F_SETFL, arg); // Trying to connect with timeout addr.sin_family = AF_INET; addr.sin_port = htons(2000); addr.sin_addr.s_addr = inet_addr("192.168.0.1"); res = connect(soc, (struct sockaddr *)&addr, sizeof(addr)); if (res < 0) { if (errno == EINPROGRESS) { tv.tv_sec = 15; tv.tv_usec = 0; FD_ZERO(&myset); FD_SET(soc, &myset); if (select(soc+1, NULL, &myset, NULL, &tv) > 0) { lon = sizeof(int); getsockopt(soc, SOL_SOCKET, SO_ERROR, (void*)(&valopt), &lon); if (valopt) { fprintf(stderr, "Error in connection() %d - %s/n", valopt, strerror(valopt)); exit(0); } } else { fprintf(stderr, "Timeout or error() %d - %s/n", valopt, strerror(valopt)); exit(0); } } else { fprintf(stderr, "Error connecting %d - %s/n", errno, strerror(errno)); exit(0); } } // Set to blocking mode again... arg = fcntl(soc, F_GETFL, NULL); arg &= (~O_NONBLOCK); fcntl(soc, F_SETFL, arg); // I hope that is all }

from：

http://www.developerweb.net/forum/showthread.php?p=13486

 

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这个是网络上查得的另一个版本，可以相互参考：

 

 /* * 带超时的非阻塞式connect()，这是W. Richard Stevens的实现 */ static int tcp_connect ( unsigned int ip, unsigned short int port, unsigned int timeout ) { struct sockaddr_in sin; int s, flags, error_value, n; fd_set rset, wset; struct timeval tv; size_t error_value_len; /* * fill in sockaddr_in structure */ memset( &sin, 0, sizeof( sin ) ); sin.sin_family = AF_INET; /* * 这两个全部是网络字节序 */ sin.sin_addr.s_addr = ip; sin.sin_port = port; error_value = 0; error_value_len = sizeof( error_value ); if ( ( s = socket( PF_INET, SOCK_STREAM, 0 ) ) < 0 ) { perror( "socket error" ); return( -1 ); } if ( ( flags = fcntl( s, F_GETFL, 0 ) ) < 0 ) { perror( "fcntl( F_GETFL ) error" ); goto tcp_connect_1; } /* * 设置非阻塞模式 */ if ( fcntl( s, F_SETFL, flags | O_NONBLOCK ) < 0 ) { perror( "fcntl( F_SETFL ) error" ); goto tcp_connect_1; } if ( ( n = connect( s, ( struct sockaddr * )&sin, sizeof( sin ) ) ) < 0 ) { /* * 由于是非阻塞的套接字，这里应该返回这个错误 */ if ( errno != EINPROGRESS ) { /* * connect error: Connection refused * * perror( "connect error" ); */ goto tcp_connect_1; } } /* * 这里可以插入其它代码，并行等待connect()完成 */ if ( n == 0 ) { /* * 即使是非阻塞的套接字，connect()也有可能立即成功返回 */ goto tcp_connect_0; } FD_ZERO( &rset ); FD_SET( s, &rset ); wset = rset; tv.tv_sec = timeout; tv.tv_usec = 0; n = select( s + 1, &rset, &wset, NULL, timeout ? &tv : NULL ); if ( n < 0 ) { perror( "select error" ); goto tcp_connect_1; } else if ( n == 0 ) { /* * fprintf( stderr, "select returned with timeout. " ); */ goto tcp_connect_1; } else if ( FD_ISSET( s, &rset ) || FD_ISSET( s, &wset ) ) { if ( getsockopt( s, SOL_SOCKET, SO_ERROR, &error_value, &error_value_len ) < 0 ) { goto tcp_connect_1; } } else { fprintf( stderr, "some error occur in tcp_connect() " ); goto tcp_connect_1; } tcp_connect_0: if ( fcntl( s, F_SETFL, flags ) < 0 ) { perror( "fcntl( F_SETFL ) error" ); goto tcp_connect_1; } if ( error_value != 0 ) { /* * Error: Connection refused * * fprintf( stderr, "Error: %s ", strerror( error_value ) ); */ goto tcp_connect_1; } n = 1; setsockopt( s, SOL_SOCKET, SO_KEEPALIVE, &n, sizeof( n ) ); return( s ); tcp_connect_1: close( s ); return( -1 ); } /* end of tcp_connect */