用select实现TCP回射程序（服务器及客户端） Linux

该程序系参考《UNP》来编写的，主要用来练习select及shutdown函数的使用。
服务器代码

#include #include #include #include #include #include #include #include #include #include #include #define PORT 8888 #define BACKLOG 100 #define MAXLINE 1024int main() { int listenfd, connfd, sockfd; int client[FD_SETSIZE]; int i, n; struct sockaddr_in servaddr, cliaddr; socklen_t clilen; fd_set rset, allset; int maxfd, maxcli; int nready; char buf[MAXLINE]; //创建监听套接字 if ((listenfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) { printf("socket error\n"); exit(1); }//写入套接字地址 bzero(&servaddr, sizeof(servaddr)); servaddr.sin_family = AF_INET; servaddr.sin_addr.s_addr = htonl(INADDR_ANY); servaddr.sin_port = htons(PORT); //绑定地址 if ((n = bind(listenfd, (struct sockaddr *) &servaddr, sizeof(servaddr))) < 0) { printf("bind error\n"); exit(1); }//监听 if ((n = listen(listenfd, BACKLOG)) < 0) { printf("listen error\n"); exit(1); }for (i = 0; i < FD_SETSIZE; i++) client[i] = -1; maxfd = listenfd; maxcli = -1; FD_ZERO(&allset); FD_SET(listenfd, &allset); for (; ; ) { rset = allset; if ((nready = select(maxfd + 1, &rset, NULL, NULL, NULL)) < 0) { printf("select error\n"); printf("%s\n", strerror(errno)); exit(1); }if (FD_ISSET(listenfd, &rset)) { //接受新连接 if ((connfd = accept(listenfd, (struct sockaddr *) &cliaddr, &clilen)) < 0) { printf("accept error\n"); exit(1); } printf("accept: %d\n", connfd); //更新连接表 for (i = 0; i < FD_SETSIZE; i++) if (client[i] < 0) { client[i] = connfd; break; }FD_SET(connfd, &allset); //更新描述符集if (connfd > maxfd) maxfd = connfd; //更新最大文件描述符if (i > maxcli) maxcli = i; //更新最大连接表索引if (--nready <= 0) continue; }for (i = 0; i <= maxcli; i++) { if ((sockfd = client[i]) < 0) continue; if (FD_ISSET(sockfd, &rset)) { if ((n = read(sockfd, buf, MAXLINE)) == 0) { if (close(sockfd) < 0) { printf("close error\n"); exit(1); } printf("close: %d\n", sockfd); FD_CLR(sockfd, &allset); client[i] = -1; } else { if (n < 0) { printf("read error\n"); exit(0); } if (n > 0) { if (write(sockfd, buf, n) < 0) { printf("write error\n"); exit(1); } } } if (--nready <= 0) break; } } } }

【用select实现TCP回射程序（服务器及客户端）】客户端代码

#include #include #include #include #include #include #include #include #include #include #define PORT 8888 #define MAXLINE 1024int main(int argc, char* argv[]) { int sockfd; int n; struct sockaddr_in servaddr; char buf[MAXLINE]; fd_set rset; int maxfd; int stdineof; if(argc != 2){ printf("invalid usage!\n"); exit(1); }if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0){ printf("socket error!\n"); exit(1); }servaddr.sin_family = AF_INET; servaddr.sin_port = htons(PORT); if((n = inet_pton(AF_INET,argv[1], &servaddr.sin_addr)) < 0){ printf("pton error\n"); exit(1); } else if(n == 0){ printf("invalid ip\n"); exit(1); }if((n = connect(sockfd, (struct sockaddr*)&servaddr, sizeof(servaddr))) < 0){ printf("connect error\n"); exit(1); }maxfd = sockfd; FD_ZERO(&rset); stdineof = 0; for(; ; ){ if(stdineof == 0) FD_SET(0, &rset); FD_SET(sockfd, &rset); if((n = select(maxfd+1, &rset, NULL, NULL, NULL)) < 0){ printf("select error\n"); exit(1); }if(FD_ISSET(0, &rset)){ if((n = read(0, buf, MAXLINE)) == 0){ stdineof = 1; if(shutdown(sockfd, SHUT_WR) < 0){ printf("shutdown error\n"); exit(1); } FD_CLR(0, &rset); continue; } else if(n < 0){ printf("stdin read error\n"); exit(1); } if((n = write(sockfd, buf, n)) < 0){ printf("socket write error\n"); exit(1); } }if(FD_ISSET(sockfd, &rset)){ if((n = read(sockfd, buf, MAXLINE)) == 0){ if(stdineof == 1) break; else{ printf("server terminated\n"); exit(1); } } else if(n < 0){ printf("socket read error\n"); exit(1); } if((n = write(1, buf, n)) < 0){ printf("stdout write error\n"); exit(1); } } } return 0; }