📄 server
字号:
function anonymous()
{
img_auto_size(this,450,true);
}
}
}" align="baseline" /></p><p>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：<br /><table style="WIDTH: 100%" cellspacing="1" cellpadding="1" align="baseline" border="1"><tbody><tr><td><p>/*----------------------源代码开始--------------------------------------------*/<br />#include <stdlib.h><br />#include <stdio.h><br />#include <unistd.h><br />#include <sys/time.h><br />#include <sys/types.h><br />#include <string.h><br />#include <signal.h><br />#include <sys/socket.h><br />#include <netinet/in.h><br />#include <arpa/inet.h><br />#include <errno.h><br /></p><p>static int forward_port;</p><p>#undef max<br />#define max(x,y) ((x) > (y) ? (x) : (y))</p><p>/*************************关于本文档************************************<br />*filename: tcpforwardport.c<br />*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<br />*tidied by: zhoulifa(<a href="mailto:zhoulifa@163.com">zhoulifa@163.com</a>) 周立发(<a href="http://zhoulifa.bokee.com/">http://zhoulifa.bokee.com</a>)<br />Linux爱好者 Linux知识传播者 SOHO族 开发者 最擅长C语言<br />*date time:2006-07-05 19:00:00<br />*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<br />* 但请遵循GPL<br />*Thanks to: Paul Sheer 感谢Paul Sheer在select_tut的man手册里提供了这份源代码<br />*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<br />*********************************************************************/</p><p>static int listen_socket (int listen_port) {<br /> struct sockaddr_in a;<br /> int s;<br /> int yes;<br /> if ((s = socket (AF_INET, SOCK_STREAM, 0)) < 0) {<br /> perror ("socket");<br /> return -1;<br /> }<br /> yes = 1;<br /> if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (char *) &yes, sizeof (yes)) <<br />0) {<br /> perror ("setsockopt");<br /> close (s);<br /> return -1;<br /> }<br /> memset (&a, 0, sizeof (a));<br /> a.sin_port = htons (listen_port);<br /> a.sin_family = AF_INET;<br /> if (bind(s, (struct sockaddr *) &a, sizeof (a)) < 0) {<br /> perror ("bind");<br /> close (s);<br /> return -1;<br /> }<br /> printf ("accepting connections on port %d\n", (int) listen_port);<br /> listen (s, 10);<br /> return s;<br />}</p><p>static int connect_socket (int connect_port, char *address) {<br /> struct sockaddr_in a;<br /> int s;<br /> if ((s = socket (AF_INET, SOCK_STREAM, 0)) < 0) {<br /> perror ("socket");<br /> close (s);<br /> return -1;<br /> }</p><p> memset (&a, 0, sizeof (a));<br /> a.sin_port = htons (connect_port);<br /> a.sin_family = AF_INET;</p><p> if (!inet_aton(address, (struct in_addr *) &a.sin_addr.s_addr)) {<br /> perror ("bad IP address format");<br /> close (s);<br /> return -1;<br /> }</p><p> if (connect(s, (struct sockaddr *) &a, sizeof (a)) < 0) {<br /> perror ("connect()");<br /> shutdown (s, SHUT_RDWR);<br /> close (s);<br /> return -1;<br /> }<br /> return s;<br />}</p><p>#define SHUT_FD1 { \<br /> if (fd1 >= 0) { \<br /> shutdown (fd1, SHUT_RDWR); \<br /> close (fd1); \<br /> fd1 = -1; \<br /> } \<br />}</p><p>#define SHUT_FD2 { \<br /> if (fd2 >= 0) { \<br /> shutdown (fd2, SHUT_RDWR); \<br /> close (fd2); \<br /> fd2 = -1; \<br /> } \<br />}</p><p>#define BUF_SIZE 1024</p><p>int main (int argc, char **argv) {<br /> int h;<br /> int fd1 = -1, fd2 = -1;<br /> char buf1[BUF_SIZE], buf2[BUF_SIZE];<br /> int buf1_avail, buf1_written;<br /> int buf2_avail, buf2_written;</p><p> if (argc != 4) {<br /> fprintf (stderr, "Usage\n\tfwd <listen-port /> <forward-to-port /><forward-to-ip-address />\n");<br /> exit (1);<br /> }</p><p> signal (SIGPIPE, SIG_IGN);</p><p> forward_port = atoi (argv[2]);</p><p> /*建立监听socket*/<br /> h = listen_socket (atoi (argv[1]));<br /> if (h < 0) exit (1);</p><p> for (;;) {<br /> int r, nfds = 0;<br /> fd_set rd, wr, er;<br /> FD_ZERO (&rd);<br /> FD_ZERO (&wr);<br /> FD_ZERO (&er);<br /> FD_SET (h, &rd);</p><p> /*把监听socket和可读socket三个一起放入select的可读句柄列表里*/<br /> nfds = max (nfds, h);<br /> if (fd1 > 0 && buf1_avail < BUF_SIZE) {<br /> FD_SET (fd1, &rd);<br /> nfds = max (nfds, fd1);<br /> }<br /> if (fd2 > 0 && buf2_avail < BUF_SIZE) {<br /> FD_SET (fd2, &rd);<br /> nfds = max (nfds, fd2);<br /> }</p><p> /*把可写socket两个一起放入select的可写句柄列表里*/<br /> if (fd1 > 0 && buf2_avail - buf2_written > 0) {<br /> FD_SET (fd1, &wr);<br /> nfds = max (nfds, fd1);<br /> }<br /> if (fd2 > 0 && buf1_avail - buf1_written > 0) {<br /> FD_SET (fd2, &wr);<br /> nfds = max (nfds, fd2);<br /> }</p><p> /*把有异常数据的socket两个一起放入select的异常句柄列表里*/<br /> if (fd1 > 0) {<br /> FD_SET (fd1, &er);<br /> nfds = max (nfds, fd1);<br /> }<br /> if (fd2 > 0) {<br /> FD_SET (fd2, &er);<br /> nfds = max (nfds, fd2);<br /> }</p><p> /*开始select*/<br /> r = select (nfds + 1, &rd, &wr, &er, NULL);</p><p> if (r == -1 && errno == EINTR) continue;<br /> if (r < 0) {<br /> perror ("select()");<br /> exit (1);<br /> }</p><p> /*处理新连接*/<br /> if (FD_ISSET (h, &rd)) {<br /> unsigned int l;<br /> struct sockaddr_in client_address;<br /> memset (&client_address, 0, l = sizeof (client_address));<br /> r = accept (h, (struct sockaddr *)&client_address, &l);<br /> if (r < 0) {<br /> perror ("accept()");<br /> } else {<br /> /*关闭原有连接，把新连接作为fd1，同时连接新的目标fd2*/<br /> SHUT_FD1;<br /> SHUT_FD2;<br /> buf1_avail = buf1_written = 0;<br /> buf2_avail = buf2_written = 0;<br /> fd1 = r;<br /> fd2 = connect_socket (forward_port, argv[3]);<br /> if (fd2 < 0) {<br /> SHUT_FD1;<br /> } else<br /> printf ("connect from %s\n", inet_ntoa(client_address.sin_addr));<br /> }<br /> }</p><p> /* NB: read oob data before normal reads */<br /> if (fd1 > 0)<br /> if (FD_ISSET (fd1, &er)) {<br /> char c;<br /> errno = 0;<br /> r = recv (fd1, &c, 1, MSG_OOB);<br /> if (r < 1) {<br /> SHUT_FD1;<br /> } else<br /> send (fd2, &c, 1, MSG_OOB);<br /> }</p><p> if (fd2 > 0)<br /> if (FD_ISSET (fd2, &er)) {<br /> char c;<br /> errno = 0;<br /> r = recv (fd2, &c, 1, MSG_OOB);<br /> if (r < 1) {<br /> SHUT_FD1;<br /> } else<br /> send (fd1, &c, 1, MSG_OOB);<br /> }</p><p> /* NB: read data from fd1 */<br /> if (fd1 > 0)<br /> if (FD_ISSET (fd1, &rd)) {<br /> r = read (fd1, buf1 + buf1_avail, BUF_SIZE - buf1_avail);<br /> if (r < 1) {<br /> SHUT_FD1;<br /> } else<br /> buf1_avail += r;<br /> }</p><p> /* NB: read data from fd2 */<br /> if (fd2 > 0)<br /> if (FD_ISSET (fd2, &rd)) {<br /> r = read (fd2, buf2 + buf2_avail, BUF_SIZE - buf2_avail);<br /> if (r < 1) {<br /> SHUT_FD2;<br /> } else<br /> buf2_avail += r;<br /> }</p><p> /* NB: write data to fd1 */<br /> if (fd1 > 0)<br /> if (FD_ISSET (fd1, &wr)) {<br /> r = write (fd1, buf2 + buf2_written, buf2_avail - buf2_written);<br /> if (r < 1) {<br /> SHUT_FD1;<br /> } else<br /> buf2_written += r;<br /> }</p><p> /* NB: write data to fd1 */<br /> if (fd2 > 0)<br /> if (FD_ISSET (fd2, &wr)) {<br /> r = write (fd2, buf1 + buf1_written, buf1_avail - buf1_written);<br /> if (r < 1) {<br /> SHUT_FD2;<br /> } else<br /> buf1_written += r;<br /> }</p><p> /* check if write data has caught read data */<br /> if (buf1_written == buf1_avail) buf1_written = buf1_avail = 0;<br /> if (buf2_written == buf2_avail) buf2_written = buf2_avail = 0;</p><p> /* one side has closed the connection, keep writing to the other side until empty */<br /> if (fd1 < 0 && buf1_avail - buf1_written == 0) {<br /> SHUT_FD2;<br /> }<br /> if (fd2 < 0 && buf2_avail - buf2_written == 0) {<br /> SHUT_FD1;<br /> }<br /> }<br /> return 0;<br />}<br />/*----------------------源代码结束--------------------------------------------*/<br /></p></td></tr></tbody></table></p>用gcc tcpforwardport.c -o MyProxy编译此程序后运行效果如下：<br /><table style="WIDTH: 100%" cellspacing="1" cellpadding="1" align="baseline" border="1"><tbody><tr><td>./MyProxy 8000 80 172.16.100.218<br />accepting connections on port 8000<br />connect from 127.0.0.1<br /></td></tr></tbody></table><p>当有用户访问本机的8000端口时，MyProxy程序将把此请求转发到172.16.100.218主机的80端口，即实现了一个http代理。</p><p>关于select函数：<br />其函数原型为：<br />int select(int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout);<br />此函数的功能是由内核检测在timeout时间内，是否有readfds，writefds，exceptfds三个句柄集(file descriptors)里的某个句柄（file descriptor)的状态符合寻求，即readfds句柄集里有句柄可读或writefds句柄集里有可写或exceptfds句柄集里有例外发生，任何一个有变化函数就立即返回，返回值为timeout发生状态变化的句柄个数。<br />n是所有readfds，writefds，exceptfds三个句柄集(file descriptors)里编号最大值加1。比如：要检测两个socket句柄fd1和fd2在timeout时间内是否分别可读和可写就可以这样：<br />先把两个句柄集(file descriptors)清零：<br /> FD_ZERO (&readfds);<br /> FD_ZERO (&writefds);<br />然后把fd1加入读检测集：<br /> FD_SET (fd1, &readfds);<br />然后把fd2加入写检测集：<br /> FD_SET (fd2, &writefds);<br />再给timeout设置值，timeout是这样的一个结构：<br /> struct timeval {<br /> long tv_sec; /* seconds */<br /> long tv_usec; /* microseconds */<br /> };<br />你可以这样赋值：<br /> timeout.tv_sec=1;<br /> timeout.tv_uec=0;<br />表示检测在1秒钟内是否有句柄状态发生变化。<br />如果有句柄发生变化，就可以用FD_ISSET检测各个句柄，比如：<br /> FD_ISSET (fd1, &readfds);//检测是否fd1变成可读的了<br /> FD_ISSET (fd2, &writefds);//检测是否fd2变成可写的了<br />示意程序代码如下：<br /><table style="WIDTH: 100%" cellspacing="1" cellpadding="1" align="baseline" border="1"><tbody><tr><td>/*----------------------示意代码开始--------------------------------------------*/<br /> fd1 = socket();//创建一个socket<br /> fd2 = socket();//创建一个socket<br /> while(1) {<br /> FD_ZERO (&readfds);<br /> FD_ZERO (&writefds);<br /> FD_SET (fd1, &readfds);<br /> FD_SET (fd2, &writefds);<br /> timeout.tv_sec=1;<br /> timeout.tv_uec=0;<br /> ret = select(fd1>fd2?(fd1+1):(fd2+1), &readfds, &writefds, NULL, &timeout);<br /> if(ret < 0) {printf("系统错误，select出错，错误代码：%d, 错误信息：%s", errno, strerror(errno));}<br /> else if(ret == 0) {printf("select超时返回，没有任何句柄状态发生变化！");}<br /> //有句柄状态发生了变化<br /> if(FD_ISSET(fd1, &readfds)) {<br /> fd1有数据可读;<br /> fd1里的数据被读出来;<br /> }<br /> if(FD_ISSET(fd2, &writefds)) {<br /> fd2可写;<br /> fd2里发送数据给对方;<br /> }<br /> }<br />/*----------------------示意代码结束--------------------------------------------*/<br /></td></tr></tbody></table></p>经常用到的几个自定义函数：<br />1、开启监听的函数<br /><table style="WIDTH: 100%" cellspacing="1" cellpadding="1" align="baseline" border="1"><tbody><tr><td><p>/*----------------------源代码代码开始--------------------------------------------*/<br />int<br />OpenSCPServer(int port, int total, int sendbuflen, int recvbuflen, int blockORnot, int reuseORnot) {<br />/*************************关于本函数************************************<br />*function_name: OpenSCPServer<br />*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<br />* 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<br />*purpose: 用来建立一个tcp服务端socket<br />*tidied by: zhoulifa(<a href="mailto:zhoulifa@163.com">zhoulifa@163.com</a>) 周立发(<a href="http://zhoulifa.bokee.com/">http://zhoulifa.bokee.com</a>)<br />Linux爱好者 Linux知识传播者 SOHO族 开发者 最擅长C语言<br />*date time:2006-07-05 20:00:00<br />*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<br />* 但请遵循GPL<br />*Thanks to: Paul Sheer 感谢Paul Sheer在select_tut的man手册里提供了这份源代码<br />*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<br />*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<br />*********************************************************************/<br /> int sockfd = 0, ret = 0, opt = 0, flags=1;<br /> struct sockaddr_in laddr;</p><p> ret = sockfd = socket(PF_INET, SOCK_STREAM, 0);<br /> if(ret < 0) {<br /> sprintf(errorMessage, "OpenTCPServer socket() error! return:%d, errno=%d, errortext:'%s' %s", ret, errno, strerror(errno), GetCurrentTime(0, 0));<br /> return -1;<br /> }</p><p> ret = setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &reuseORnot, sizeof(int));<br /> if(ret < 0) {<br /> sprintf(errorMessage, "OpenTCPServer setsockopt() reuse error! return:%d, errno=%d, errortext:'%s' %s", ret, errno, strerror(errno), GetCurrentTime(0, 0));<br /> return -2;<br /> }</p><p> ret = setsockopt(sockfd, SOL_SOCKET, SO_RCVBUF, &recvbuflen, sizeof(int));<br /> if ( ret < 0) {<br /> sprintf(errorMessage, "OpenTCPServer setsockopt() recvbuf error! return:%d, errno=%d, errortext:'%s' %s", ret, errno, strerror(errno), GetCurrentTime(0, 0));<br /> return -3;<br /> }</p><p> ret = setsockopt(sockfd, SOL_SOCKET, SO_SNDBUF, &sendbuflen, sizeof(int));<br /> if (ret < 0) {<br /> sprintf(errorMessage, "OpenTCPServer setsockopt() sendbuf error! return:%d, errno=%d, errortext:'%s' %s", ret, errno, strerror(errno), GetCurrentTime(0, 0));<br /> return -4;<br /> }</p><p> ioctl(sockfd,FIONBIO,&blockORnot);/*block or not*/</p><p> laddr.sin_family = PF_INET;<br /> laddr.sin_port = htons(port);<br /> laddr.sin_addr.s_addr = INADDR_ANY;<br /> bzero(&(laddr.sin_zero), 8);</p><p> ret = bind(sockfd, (struct sockaddr *)&laddr, sizeof(struct sockaddr));<br /> if(ret < 0) {<br /> sprintf(errorMessage, "OpenTCPServer bind() error! return:%d, errno=%d, errortext:'%s' %s", ret, errno, strerror(errno), GetCurrentTime(0, 0));<br /> close(sockfd);<br /> return -5;<br /> }<br /> ret = listen(sockfd, total);<br /> if(ret < 0) {<br /> sprintf(errorMessage, "OpenTCPServer listen() error! return:%d, errno=%d, errortext:'%s' %s", ret, errno, strerror(errno), GetCurrentTime(0, 0));<br /> close(sockfd);<br /> return -6;<br /> }<br /> sprintf(errorMessage, "OpenTCPServer opened on port.%d(%d) OK, socket(%d), buf(%d:%d)! %s", port, total, sockfd, sendbuflen, recvbuflen, GetCurrentTime(0, 0));<br /> return sockfd;<br />}<br />/*----------------------源代码代码结束--------------------------------------------*/<br /></p></td></tr></tbody></table>2、连接服务器的函数<br /><table style="WIDTH: 100%" cellspac⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -