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大家都知道各类网络服务器程序的编写步骤,并且都知道网络服务器就两大类:循环服务和并发服务。这里附上源代码来个小结吧。
首先,循环网络服务器编程实现的步骤是这样的:这种服务器模型是典型循环服务,如果不加上多进程/线程技术,此种服务吞吐量有限,大家都可以看到,如果前一个连接服务数据没有收发完毕后面的连接没办法处理。所以一般有多进程技术,对一个新连接启用一个新进程去处理,而监听socket继续监听。
/************关于本文档*********************************************filename: Linux下各类TCP网络服务器的实现源代码*purpose: 记录Linux下各类tcp服务程序源代码*wrote by: zhoulifa(zhoulifa@163.com) 周立发()Linux爱好者 Linux知识传播者 SOHO族 开发者 最擅长C语言*date time:2006-07-04 22:00:00*Note: 任何人可以任意复制代码并运用这些文档,当然包括你的商业用途* 但请遵循GPL*Hope:希望越来越多的人贡献自己的力量,为科学技术发展出力*********************************************************************/一个循环TCP服务源代码(因为用fork进行多进程服务了,所以这种服务现实中也有用)如下:/*----------------------源代码开始--------------------------------------------*/#include#include #include #include #include #include #include #include /**********************************************************************filename: cycletcpserver.c*purpose: 循环tcp服务端程序*tidied by: zhoulifa(zhoulifa@163.com) 周立发(http://zhoulifa.bokee.com)Linux爱好者 Linux知识传播者 SOHO族 开发者 最擅长C语言*date time:2006-07-04 22:00:00*Note: 任何人可以任意复制代码并运用这些文档,当然包括你的商业用途* 但请遵循GPL*Thanks to: Google.com*********************************************************************/int main(int argc, char ** argv){ int sockfd,new_fd; /* 监听socket: sock_fd,数据传输socket: new_fd */ struct sockaddr_in my_addr; /* 本机地址信息 */ struct sockaddr_in their_addr; /* 客户地址信息 */ unsigned int sin_size, myport, lisnum; if(argv[1]) myport = atoi(argv[1]); else myport = 7838; if(argv[2]) lisnum = atoi(argv[2]); else lisnum = 2; if ((sockfd = socket(PF_INET, SOCK_STREAM, 0)) == -1) { perror("socket"); exit(1); } my_addr.sin_family=PF_INET; my_addr.sin_port=htons(myport); my_addr.sin_addr.s_addr = INADDR_ANY; bzero(&(my_addr.sin_zero), 0); if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr)) == -1) { perror("bind"); exit(1); } if (listen(sockfd, lisnum) == -1) { perror("listen"); exit(1); } while(1) { sin_size = sizeof(struct sockaddr_in); if ((new_fd = accept(sockfd, (struct sockaddr *)&their_addr, &sin_size)) == -1) { perror("accept"); continue; } printf("server: got connection from %s\n",inet_ntoa(their_addr.sin_addr)); if (!fork()) { /* 子进程代码段 */ if (send(new_fd, "Hello, world!\n", 14, 0) == -1) { perror("send"); close(new_fd); exit(0); } } close(new_fd); /*父进程不再需要该socket*/ waitpid(-1,NULL,WNOHANG);/*等待子进程结束,清除子进程所占用资源*/ }}/*----------------------源代码结束--------------------------------------------*/
一个测试客户端代码如下:
/*----------------------源代码开始--------------------------------------------*/#include#include #include #include #include #include #include #include #define MAXDATASIZE 100 /*每次最大数据传输量 *//**********************************************************************filename: cycletcpclient.c*purpose: 循环tcp客户端程序*tidied by: zhoulifa(zhoulifa@163.com) 周立发(http://zhoulifa.bokee.com)Linux爱好者 Linux知识传播者 SOHO族 开发者 最擅长C语言*date time:2006-07-04 22:20:00*Note: 任何人可以任意复制代码并运用这些文档,当然包括你的商业用途* 但请遵循GPL*Thanks to: Google.com*Hope:希望越来越多的人贡献自己的力量,为科学技术发展出力*********************************************************************/int main(int argc, char *argv[]){ int sockfd, numbytes; char buf[MAXDATASIZE]; struct hostent *he; struct sockaddr_in their_addr; unsigned int myport; if(argv[2]) myport = atoi(argv[2]); else myport = 7838; if (argc != 3) { fprintf(stderr,"usage: %s hostname port\n", argv[0]); exit(1); } if((he=gethostbyname(argv[1]))==NULL) { herror("gethostbyname"); exit(1); } if ((sockfd = socket(PF_INET, SOCK_STREAM, 0)) == -1) { perror("socket"); exit(1); } their_addr.sin_family=PF_INET; their_addr.sin_port=htons(myport); their_addr.sin_addr = *((struct in_addr *)he->h_addr); bzero(&(their_addr.sin_zero),0); if (connect(sockfd, (struct sockaddr *)&their_addr, sizeof(struct sockaddr)) == -1) { perror("connect"); exit(1); } if ((numbytes=recv(sockfd, buf, MAXDATASIZE, 0)) == -1) { perror("recv"); exit(1); } buf[numbytes] = 0; printf("Received: %s\n",buf); close(sockfd); return 0;}/*----------------------源代码结束--------------------------------------------*/
用gcc cycletcpserver.c -o tcpserver和gcc cycletcpclient.c -o tcpclient分别编译上述代码后运行情况如下:
服务端运行显示:administrator@ubuzlf:/data/example/c$ ./tcpserver server: got connection from 127.0.0.1 server: got connection from 127.0.0.1 server: got connection from 127.0.0.1
administrator@ubuzlf:/data/example/c$ ./tcpclient 127.0.0.1 7838 Received: Hello, world! administrator@ubuzlf:/data/example/c$ ./tcpclient 127.0.0.1 7838 Received: Hello, world! administrator@ubuzlf:/data/example/c$ ./tcpclient 127.0.0.1 7838 Received: Hello, world!
下面是一个演示IO多路复用的源程序,是一个端口转发程序,但它的用处相当大,实际应用中的各类代理软件或端口映射软件都是基于这样的代码的,比如Windows下的WinGate、WinProxy等都是在此基础上实现的。源代码如下:
/*----------------------源代码开始--------------------------------------------*/#include#include #include #include #include #include #include #include #include #include #include static int forward_port;#undef max#define max(x,y) ((x) > (y) ? (x) : (y))/*************************关于本文档*************************************filename: tcpforwardport.c*purpose: 演示了select的用法,这是一个极好的代理软件核心,专门作端口映射用*tidied by: zhoulifa(zhoulifa@163.com) 周立发(http://zhoulifa.bokee.com)Linux爱好者 Linux知识传播者 SOHO族 开发者 最擅长C语言*date time:2006-07-05 19:00:00*Note: 任何人可以任意复制代码并运用这些文档,当然包括你的商业用途* 但请遵循GPL*Thanks to: Paul Sheer 感谢Paul Sheer在select_tut的man手册里提供了这份源代码*Hope:希望越来越多的人贡献自己的力量,为科学技术发展出力*********************************************************************/static int listen_socket (int listen_port) { struct sockaddr_in a; int s; int yes; if ((s = socket (AF_INET, SOCK_STREAM, 0)) < 0) { perror ("socket"); return -1; } yes = 1; if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (char *) &yes, sizeof (yes)) <0) { perror ("setsockopt"); close (s); return -1; } memset (&a, 0, sizeof (a)); a.sin_port = htons (listen_port); a.sin_family = AF_INET; if (bind(s, (struct sockaddr *) &a, sizeof (a)) < 0) { perror ("bind"); close (s); return -1; } printf ("accepting connections on port %d\n", (int) listen_port); listen (s, 10); return s;}static int connect_socket (int connect_port, char *address) { struct sockaddr_in a; int s; if ((s = socket (AF_INET, SOCK_STREAM, 0)) < 0) { perror ("socket"); close (s); return -1; } memset (&a, 0, sizeof (a)); a.sin_port = htons (connect_port); a.sin_family = AF_INET; if (!inet_aton(address, (struct in_addr *) &a.sin_addr.s_addr)) { perror ("bad IP address format"); close (s); return -1; } if (connect(s, (struct sockaddr *) &a, sizeof (a)) < 0) { perror ("connect()"); shutdown (s, SHUT_RDWR); close (s); return -1; } return s;}#define SHUT_FD1 { \ if (fd1 >= 0) { \ shutdown (fd1, SHUT_RDWR); \ close (fd1); \ fd1 = -1; \ } \}#define SHUT_FD2 { \ if (fd2 >= 0) { \ shutdown (fd2, SHUT_RDWR); \ close (fd2); \ fd2 = -1; \ } \}#define BUF_SIZE 1024int main (int argc, char **argv) { int h; int fd1 = -1, fd2 = -1; char buf1[BUF_SIZE], buf2[BUF_SIZE]; int buf1_avail, buf1_written; int buf2_avail, buf2_written; if (argc != 4) { fprintf (stderr, "Usage\n\tfwd \n"); exit (1); } signal (SIGPIPE, SIG_IGN); forward_port = atoi (argv[2]); /*建立监听socket*/ h = listen_socket (atoi (argv[1])); if (h < 0) exit (1); for (;;) { int r, nfds = 0; fd_set rd, wr, er; FD_ZERO (&rd); FD_ZERO (&wr); FD_ZERO (&er); FD_SET (h, &rd); /*把监听socket和可读socket三个一起放入select的可读句柄列表里*/ nfds = max (nfds, h); if (fd1 > 0 && buf1_avail < BUF_SIZE) { FD_SET (fd1, &rd); nfds = max (nfds, fd1); } if (fd2 > 0 && buf2_avail < BUF_SIZE) { FD_SET (fd2, &rd); nfds = max (nfds, fd2); } /*把可写socket两个一起放入select的可写句柄列表里*/ if (fd1 > 0 && buf2_avail - buf2_written > 0) { FD_SET (fd1, &wr); nfds = max (nfds, fd1); } if (fd2 > 0 && buf1_avail - buf1_written > 0) { FD_SET (fd2, &wr); nfds = max (nfds, fd2); } /*把有异常数据的socket两个一起放入select的异常句柄列表里*/ if (fd1 > 0) { FD_SET (fd1, &er); nfds = max (nfds, fd1); } if (fd2 > 0) { FD_SET (fd2, &er); nfds = max (nfds, fd2); } /*开始select*/ r = select (nfds + 1, &rd, &wr, &er, NULL); if (r == -1 && errno == EINTR) continue; if (r < 0) { perror ("select()"); exit (1); } /*处理新连接*/ if (FD_ISSET (h, &rd)) { unsigned int l; struct sockaddr_in client_address; memset (&client_address, 0, l = sizeof (client_address)); r = accept (h, (struct sockaddr *)&client_address, &l); if (r < 0) { perror ("accept()"); } else { /*关闭原有连接,把新连接作为fd1,同时连接新的目标fd2*/ SHUT_FD1; SHUT_FD2; buf1_avail = buf1_written = 0; buf2_avail = buf2_written = 0; fd1 = r; fd2 = connect_socket (forward_port, argv[3]); if (fd2 < 0) { SHUT_FD1; } else printf ("connect from %s\n", inet_ntoa(client_address.sin_addr)); } } /* NB: read oob data before normal reads */ if (fd1 > 0) if (FD_ISSET (fd1, &er)) { char c; errno = 0; r = recv (fd1, &c, 1, MSG_OOB); if (r < 1) { SHUT_FD1; } else send (fd2, &c, 1, MSG_OOB); } if (fd2 > 0) if (FD_ISSET (fd2, &er)) { char c; errno = 0; r = recv (fd2, &c, 1, MSG_OOB); if (r < 1) { SHUT_FD1; } else send (fd1, &c, 1, MSG_OOB); } /* NB: read data from fd1 */ if (fd1 > 0) if (FD_ISSET (fd1, &rd)) { r = read (fd1, buf1 + buf1_avail, BUF_SIZE - buf1_avail); if (r < 1) { SHUT_FD1; } else buf1_avail += r; } /* NB: read data from fd2 */ if (fd2 > 0) if (FD_ISSET (fd2, &rd)) { r = read (fd2, buf2 + buf2_avail, BUF_SIZE - buf2_avail); if (r < 1) { SHUT_FD2; } else buf2_avail += r; } /* NB: write data to fd1 */ if (fd1 > 0) if (FD_ISSET (fd1, &wr)) { r = write (fd1, buf2 + buf2_written, buf2_avail - buf2_written); if (r < 1) { SHUT_FD1; } else buf2_written += r; } /* NB: write data to fd1 */ if (fd2 > 0) if (FD_ISSET (fd2, &wr)) { r = write (fd2, buf1 + buf1_written, buf1_avail - buf1_written); if (r < 1) { SHUT_FD2; } else buf1_written += r; } /* check if write data has caught read data */ if (buf1_written == buf1_avail) buf1_written = buf1_avail = 0; if (buf2_written == buf2_avail) buf2_written = buf2_avail = 0; /* one side has closed the connection, keep writing to the other side until empty */ if (fd1 < 0 && buf1_avail - buf1_written == 0) { SHUT_FD2; } if (fd2 < 0 && buf2_avail - buf2_written == 0) { SHUT_FD1; } } return 0;}/*----------------------源代码结束--------------------------------------------*/
用gcc tcpforwardport.c -o MyProxy编译此程序后运行效果如下:
./MyProxy 8000 80 172.16.100.218 accepting connections on port 8000 connect from 127.0.0.1
/*----------------------示意代码开始--------------------------------------------*/ fd1 = socket();//创建一个socket fd2 = socket();//创建一个socket while(1) { FD_ZERO (&readfds); FD_ZERO (&writefds); FD_SET (fd1, &readfds); FD_SET (fd2, &writefds); timeout.tv_sec=1; timeout.tv_uec=0; ret = select(fd1>fd2?(fd1+1):(fd2+1), &readfds, &writefds, NULL, &timeout); if(ret < 0) {printf("系统错误,select出错,错误代码:%d, 错误信息:%s", errno, strerror(errno));} else if(ret == 0) {printf("select超时返回,没有任何句柄状态发生变化!");} //有句柄状态发生了变化 if(FD_ISSET(fd1, &readfds)) { fd1有数据可读; fd1里的数据被读出来; } if(FD_ISSET(fd2, &writefds)) { fd2可写; fd2里发送数据给对方; } }/*----------------------示意代码结束--------------------------------------------*/用gcc tcpforwardport.c -o MyProxy编译此程序后运行效果如下:
./MyProxy 8000 80 172.16.100.218 accepting connections on port 8000 connect from 127.0.0.1
/*----------------------示意代码开始--------------------------------------------*/ fd1 = socket();//创建一个socket fd2 = socket();//创建一个socket while(1) { FD_ZERO (&readfds); FD_ZERO (&writefds); FD_SET (fd1, &readfds); FD_SET (fd2, &writefds); timeout.tv_sec=1; timeout.tv_uec=0; ret = select(fd1>fd2?(fd1+1):(fd2+1), &readfds, &writefds, NULL, &timeout); if(ret < 0) {printf("系统错误,select出错,错误代码:%d, 错误信息:%s", errno, strerror(errno));} else if(ret == 0) {printf("select超时返回,没有任何句柄状态发生变化!");} //有句柄状态发生了变化 if(FD_ISSET(fd1, &readfds)) { fd1有数据可读; fd1里的数据被读出来; } if(FD_ISSET(fd2, &writefds)) { fd2可写; fd2里发送数据给对方; } }/*----------------------示意代码结束--------------------------------------------*/
经常用到的几个自定义函数:
1、开启监听的函数/*----------------------源代码代码开始--------------------------------------------*/intOpenSCPServer(int port, int total, int sendbuflen, int recvbuflen, int blockORnot, int reuseORnot) {/*************************关于本函数*************************************function_name: OpenSCPServer*参数说明:port整数型监听端口号,total整数型监听个数,sendbuflen整数型发送缓冲区大小* recvbuflen整数型接收缓冲区大小,blockORnot整数型是否阻塞,reuseORnot整数型是否端口重用*purpose: 用来建立一个tcp服务端socket*tidied by: zhoulifa(zhoulifa@163.com) 周立发(http://zhoulifa.bokee.com)Linux爱好者 Linux知识传播者 SOHO族 开发者 最擅长C语言*date time:2006-07-05 20:00:00*Note: 任何人可以任意复制代码并运用这些文档,当然包括你的商业用途* 但请遵循GPL*Thanks to: Paul Sheer 感谢Paul Sheer在select_tut的man手册里提供了这份源代码*Hope:希望越来越多的人贡献自己的力量,为科学技术发展出力*Note:要使用此函数需要自定义一个全局变量char errorMessage[1024];并包含GetCurrentTime.h头文件*********************************************************************/ int sockfd = 0, ret = 0, opt = 0, flags=1; struct sockaddr_in laddr; ret = sockfd = socket(PF_INET, SOCK_STREAM, 0); if(ret < 0) { sprintf(errorMessage, "OpenTCPServer socket() error! return:%d, errno=%d, errortext:'%s' %s", ret, errno, strerror(errno), GetCurrentTime(0, 0)); return -1; } ret = setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &reuseORnot, sizeof(int)); if(ret < 0) { sprintf(errorMessage, "OpenTCPServer setsockopt() reuse error! return:%d, errno=%d, errortext:'%s' %s", ret, errno, strerror(errno), GetCurrentTime(0, 0)); return -2; } ret = setsockopt(sockfd, SOL_SOCKET, SO_RCVBUF, &recvbuflen, sizeof(int)); if ( ret < 0) { sprintf(errorMessage, "OpenTCPServer setsockopt() recvbuf error! return:%d, errno=%d, errortext:'%s' %s", ret, errno, strerror(errno), GetCurrentTime(0, 0)); return -3; } ret = setsockopt(sockfd, SOL_SOCKET, SO_SNDBUF, &sendbuflen, sizeof(int)); if (ret < 0) { sprintf(errorMessage, "OpenTCPServer setsockopt() sendbuf error! return:%d, errno=%d, errortext:'%s' %s", ret, errno, strerror(errno), GetCurrentTime(0, 0)); return -4; } ioctl(sockfd,FIONBIO,&blockORnot);/*block or not*/ laddr.sin_family = PF_INET; laddr.sin_port = htons(port); laddr.sin_addr.s_addr = INADDR_ANY; bzero(&(laddr.sin_zero), 8); ret = bind(sockfd, (struct sockaddr *)&laddr, sizeof(struct sockaddr)); if(ret < 0) { sprintf(errorMessage, "OpenTCPServer bind() error! return:%d, errno=%d, errortext:'%s' %s", ret, errno, strerror(errno), GetCurrentTime(0, 0)); close(sockfd); return -5; } ret = listen(sockfd, total); if(ret < 0) { sprintf(errorMessage, "OpenTCPServer listen() error! return:%d, errno=%d, errortext:'%s' %s", ret, errno, strerror(errno), GetCurrentTime(0, 0)); close(sockfd); return -6; } sprintf(errorMessage, "OpenTCPServer opened on port.%d(%d) OK, socket(%d), buf(%d:%d)! %s", port, total, sockfd, sendbuflen, recvbuflen, GetCurrentTime(0, 0)); return sockfd;}/*----------------------源代码代码结束--------------------------------------------*/
2、连接服务器的函数
/*----------------------源代码代码开始--------------------------------------------*/intConnectSCPServer(char * serverip, int serverport, int blockORnot) {/*************************关于本函数*************************************function_name: ConnectSCPServer*参数说明:serverip服务器IP地址或主机名,serverport服务器端口,blockORnot整数型是否阻塞*purpose: 用来建立一个tcp客户端socket*tidied by: zhoulifa(zhoulifa@163.com) 周立发(http://zhoulifa.bokee.com)Linux爱好者 Linux知识传播者 SOHO族 开发者 最擅长C语言*date time:2006-07-05 20:40:00*Note: 任何人可以任意复制代码并运用这些文档,当然包括你的商业用途* 但请遵循GPL*Thanks to: Paul Sheer 感谢Paul Sheer在select_tut的man手册里提供了这份源代码*Hope:希望越来越多的人贡献自己的力量,为科学技术发展出力*Note:要使用此函数需要自定义一个全局变量char errorMessage[1024];并包含自己编写的GetCurrentTime.h头文件*********************************************************************/ int serversock = 0, ret = 0; unsigned long addr; struct sockaddr_in sin; struct hostent *he; if((he=gethostbyname(serverip))== 0) { sprintf(errorMessage, "ConnectSCPServer IP address '%s' error! return:-1 %s", serverip, GetCurrentTime(0, 0)); return -1; } serversock = socket(PF_INET, SOCK_STREAM, 0); if(serversock == -1) { sprintf(errorMessage, "ConnectSCPServer socket() error! return:-2, errno=%d, errortext:'%s' %s", errno, strerror(errno), GetCurrentTime(0, 0)); return -2; } ioctl(serversock, FIONBIO, &blockORnot); //block or not memset((char*)&sin, 0, sizeof(struct sockaddr_in)); sin.sin_family = PF_INET; sin.sin_port = htons(serverport); sin.sin_addr = *((struct in_addr *)he->h_addr); ret = connect(serversock, (struct sockaddr *)&sin, sizeof(sin)); if(ret == -1) { sprintf(errorMessage, "ConnectSCPServer connect() error! return:-3, errno=%d, errortext:'%s' %s", errno, strerror(errno), GetCurrentTime(0, 0)); close(serversock); return -3; } return serversock;}/*----------------------源代码代码结束--------------------------------------------*/发送数据函数Send
/*----------------------源代码代码开始--------------------------------------------*/intSend(int sock, char * buf, size_t size, int flag, int timeout) {/*************************关于本函数*************************************function_name: Send*参数说明:sock整数型socket,buf待发送的内容,size要发送的大小,flag发送选项,timeout超时时间值*purpose: 用来通过一个socket在指定时间内发送数据*tidied by: zhoulifa(zhoulifa@163.com) 周立发(http://zhoulifa.bokee.com)Linux爱好者 Linux知识传播者 SOHO族 开发者 最擅长C语言*date time:2006-07-05 20:58:00*Note: 任何人可以任意复制代码并运用这些文档,当然包括你的商业用途* 但请遵循GPL*Thanks to: Paul Sheer 感谢Paul Sheer在select_tut的man手册里提供了这份源代码*Hope:希望越来越多的人贡献自己的力量,为科学技术发展出力*Note:要使用此函数需要自定义一个全局变量char errorMessage[1024];并包含自己编写的GetCurrentTime.h头文件*********************************************************************/ int i = 0, ret = 0, intretry = 0; struct timeval tival; fd_set writefds; int maxfds = 0; tival.tv_sec = timeout; tival.tv_usec = 0; FD_ZERO(&writefds); if(sock > 0) { FD_SET(sock, &writefds); maxfds=((sock > maxfds)?sock:maxfds); } else { sprintf(errorMessage, "Send socket:%d error! return:-2 %s", sock, GetCurrentTime(0, 0)); return -2; } ret = select(maxfds + 1, NULL, &writefds, NULL, &tival); if(ret <= 0) { if(ret < 0) sprintf(errorMessage, "Send socket:%d select() error! return:%d, errno=%d, errortext:'%s' %s", sock, ret, errno, strerror(errno), GetCurrentTime(0, 0)); else sprintf(errorMessage, "Send socket:%d select timeout(%d)! %s", sock, timeout, GetCurrentTime(0, 0)); close(sock); return -3; } if(!(FD_ISSET(sock, &writefds))) { sprintf(errorMessage, "Send socket:%d not in writefds! %s", sock, GetCurrentTime(0, 0)); close(sock); return -4; } while(i < size) { ret = send(sock, buf + i, size - i, flag); if(ret <= 0) { sprintf(errorMessage, "Send socket:%d send() error! return:%d, errno=%d, errortext:'%s' %s", sock, ret, errno, strerror(errno), GetCurrentTime(0, 0)); if (EINTR == errno) if(intretry < 10) {intretry++;continue;} else sprintf(errorMessage, "Send socket:%d send() error!EINTR 10 times! %s", sock, GetCurrentTime(0, 0)); close(sock); return -1; } else i += ret; } sprintf(errorMessage, "Send socket:%d send() OK! %d/%d bytes sent! %s", sock, i, size, GetCurrentTime(0, 0)); return i;}/*----------------------源代码代码结束--------------------------------------------*/
4、接收数据函数Recv
/*----------------------源代码代码开始--------------------------------------------*/intRecv(int sock, char * buf, size_t size, int flag, int timeout) {/*************************关于本函数*************************************function_name: Recv*参数说明:sock整数型socket,buf接收数据的缓冲区,size要接收数据的大小,flag接收选项,timeout超时时间值*purpose: 用来从一个socket在指定时间内读取数据*tidied by: zhoulifa(zhoulifa@163.com) 周立发(http://zhoulifa.bokee.com)Linux爱好者 Linux知识传播者 SOHO族 开发者 最擅长C语言*date time:2006-07-05 21:10:00*Note: 任何人可以任意复制代码并运用这些文档,当然包括你的商业用途* 但请遵循GPL*Thanks to: Paul Sheer 感谢Paul Sheer在select_tut的man手册里提供了这份源代码*Hope:希望越来越多的人贡献自己的力量,为科学技术发展出力*Note:要使用此函数需要自定义一个全局变量char errorMessage[1024];并包含自己编写的GetCurrentTime.h头文件*********************************************************************/ int i = 0, ret = 0, intretry = 0; struct timeval tival; fd_set readfds; int maxfds = 0; tival.tv_sec = timeout; tival.tv_usec = 0; FD_ZERO(&readfds); if(sock > 0) { FD_SET(sock, &readfds); maxfds=((sock > maxfds)?sock:maxfds); } else { sprintf(errorMessage, "Recv socket:%d error! return:-2 %s", sock, GetCurrentTime(0, 0)); return -2; } ret = select(maxfds + 1, &readfds, NULL, NULL, &tival); if(ret <= 0) { if(ret < 0) sprintf(errorMessage, "Recv socket:%d select() error! return:%d, errno=%d, errortext:'%s' %s", sock, ret, errno, strerror(errno), GetCurrentTime(0, 0)); else sprintf(errorMessage, "Recv socket:%d select timeout(%d)! %s", sock, timeout, GetCurrentTime(0, 0)); close(sock); return -3; } if(!(FD_ISSET(sock, &readfds))) { sprintf(errorMessage, "Recv socket:%d not in readfds! %s", sock, GetCurrentTime(0, 0)); close(sock); return -4; } while(i < size) { ret = recv(sock, buf + i, size - i, flag); if(ret <= 0){ sprintf(errorMessage, "Recv socket:%d recv() error! return:%d, errno=%d, errortext:'%s' %s", sock, ret, errno, strerror(errno), GetCurrentTime(0, 0)); if(errno == EINTR) if(intretry < 10) {intretry++;continue;} else sprintf(errorMessage, "Recv socket:%d recv() error! EINTR 10 times! %s", sock, GetCurrentTime(0, 0)); close(sock); return -1; } else i += ret; } sprintf(errorMessage, "Recv socket:%d recv() OK! %d/%d bytes received! %s", sock, i, size, GetCurrentTime(0, 0)); return i;}
最后需要说明的是:我这里讲到的源程序并不能实际地作为一个产品程序来用,实际情况下可能会有其它许多工作要做,比如可能要建立共享队列来存放 socket里读到的消息,也可能把发送消息先进行排队然后再调用Send函数。还有,如果不是全数字,在发送前一定要htonl转换为网络字节序,同理接收到后一定要先ntohl由网络字节序转换为主机字节序,否则对方发送过来的0x00000001在你这里可能是0x00010000,因为高低位顺序不同。
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