Linux/Unix IO多路复用之select网络编程(含源码)
作者:互联网
前言
本章节是用基本的Linux/Unix基本函数加上select调用编写一个完整的服务器和客户端例子,可在Linux(ubuntu)和Unix(freebsd)上运行,客户端和服务端的功能如下:
客户端从标准输入读入一行,发送到服务端
服务端从网络读取一行,然后输出到客户端
客户端收到服务端的响应,输出这一行到标准输出
服务端
代码如下:
#include <unistd.h> #include <sys/types.h> /* basic system data types */ #include <sys/socket.h> /* basic socket definitions */ #include <netinet/in.h> /* sockaddr_in{} and other Internet defns */ #include <arpa/inet.h> /* inet(3) functions */ #include <sys/select.h> /* select function*/ #include <stdlib.h> #include <errno.h> #include <stdio.h> #include <string.h> #define MAXLINE 10240 void handle(int * clientSockFds, int maxFds, fd_set* pRset, fd_set* pAllset); int main(int argc, char **argv) { int servPort = 6888; int listenq = 1024; int listenfd, connfd; struct sockaddr_in cliaddr, servaddr; socklen_t socklen = sizeof(struct sockaddr_in); int nready, nread; char buf[MAXLINE]; int clientSockFds[FD_SETSIZE]; fd_set allset, rset; int maxfd; listenfd = socket(AF_INET, SOCK_STREAM, 0); if (listenfd < 0) { perror("socket error"); return -1; } int opt = 1; if (setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) < 0) { perror("setsockopt error"); } bzero(&servaddr, sizeof(servaddr)); servaddr.sin_family = AF_INET; servaddr.sin_addr.s_addr = htonl(INADDR_ANY); servaddr.sin_port = htons(servPort); if(bind(listenfd, (struct sockaddr*)&servaddr, socklen) == -1) { perror("bind error"); exit(-1); } if (listen(listenfd, listenq) < 0) { perror("listen error"); return -1; } int i = 0; for (i = 0; i< FD_SETSIZE; i++) clientSockFds[i] = -1; FD_ZERO(&allset); FD_SET(listenfd, &allset); maxfd = listenfd; printf("echo server use select startup, listen on port %d\n", servPort); printf("max connection: %d\n", FD_SETSIZE); for ( ; ; ) { rset = allset; nready = select(maxfd + 1, &rset, NULL, NULL, NULL); if (nready < 0) { perror("select error"); continue; } if (FD_ISSET(listenfd, &rset)) { connfd = accept(listenfd, (struct sockaddr*) &cliaddr, &socklen); if (connfd < 0) { perror("accept error"); continue; } sprintf(buf, "accept form %s:%d\n", inet_ntoa(cliaddr.sin_addr), cliaddr.sin_port); printf(buf, ""); for (i = 0; i< FD_SETSIZE; i++) { if (clientSockFds[i] == -1) { clientSockFds[i] = connfd; break; } } if (i == FD_SETSIZE) { fprintf(stderr, "too many connection, more than %d\n", FD_SETSIZE); close(connfd); continue; } if (connfd > maxfd) maxfd = connfd; FD_SET(connfd, &allset); if (--nready <= 0) continue; } handle(clientSockFds, maxfd, &rset, &allset); } } void handle(int * clientSockFds, int maxFds, fd_set* pRset, fd_set* pAllset) { int nread; int i; char buf[MAXLINE]; for (i = 0; i< maxFds; i++) { if (clientSockFds[i] != -1) { if (FD_ISSET(clientSockFds[i], pRset)) { nread = read(clientSockFds[i], buf, MAXLINE);//读取客户端socket流 if (nread < 0) { perror("read error"); close(clientSockFds[i]); FD_CLR(clientSockFds[i], pAllset); clientSockFds[i] = -1; continue; } if (nread == 0) { printf("client close the connection\n"); close(clientSockFds[i]); FD_CLR(clientSockFds[i], pAllset); clientSockFds[i] = -1; continue; } write(clientSockFds[i], buf, nread);//响应客户端 有可能失败,暂不处理 } } } }
客户端
代码如下:
#include <unistd.h> #include <sys/types.h> /* basic system data types */ #include <sys/socket.h> /* basic socket definitions */ #include <netinet/in.h> /* sockaddr_in{} and other Internet defns */ #include <arpa/inet.h> /* inet(3) functions */ #include <sys/select.h> /* select function*/ #include <stdlib.h> #include <errno.h> #include <stdio.h> #include <string.h> #define MAXLINE 10240 #define max(a,b) ((a) > (b) ? (a) : (b)) //typedef struct sockaddr SA; void handle(int sockfd); int main(int argc, char **argv) { char * servInetAddr = "127.0.0.1"; int servPort = 6888; char buf[MAXLINE]; int connfd; struct sockaddr_in servaddr; if (argc == 2) { servInetAddr = argv[1]; } if (argc == 3) { servInetAddr = argv[1]; servPort = atoi(argv[2]); } if (argc > 3) { printf("usage: selectechoclient <IPaddress> <Port>\n"); return -1; } connfd = socket(AF_INET, SOCK_STREAM, 0); bzero(&servaddr, sizeof(servaddr)); servaddr.sin_family = AF_INET; servaddr.sin_port = htons(servPort); inet_pton(AF_INET, servInetAddr, &servaddr.sin_addr); if (connect(connfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) < 0) { perror("connect error"); return -1; } printf("welcome to selectechoclient\n"); handle(connfd); /* do it all */ close(connfd); printf("exit\n"); exit(0); } void handle(int connfd) { FILE* fp = stdin; char sendline[MAXLINE], recvline[MAXLINE]; fd_set rset; FD_ZERO(&rset); int maxfds = max(fileno(fp), connfd) + 1; int nread; for (;;) { FD_SET(fileno(fp), &rset); FD_SET(connfd, &rset); if (select(maxfds, &rset, NULL, NULL, NULL) == -1) { perror("select error"); continue; } if (FD_ISSET(connfd, &rset)) { //接收到服务器响应 nread = read(connfd, recvline, MAXLINE); if (nread == 0) { printf("server close the connection\n"); break; } else if (nread == -1) { perror("read error"); break; } else { //server response write(STDOUT_FILENO, recvline, nread); } } if (FD_ISSET(fileno(fp), &rset)) { //标准输入可读 if (fgets(sendline, MAXLINE, fp) == NULL) { //eof exit break; } else { write(connfd, sendline, strlen(sendline)); } } } }
编译和启动服务端
gcc selectechoserver.c -o selectechoserver
编译和启动客户端
gcc selectechoclient.c -o selectechoclient
标签:int,rset,Unix,源码,FD,IO,connfd,include,servaddr 来源: https://blog.csdn.net/daocaokafei/article/details/113813461