Huangea Blog 嵌入式博客解决多客户端高并发的问题，通过非阻塞的模式去轮训多个clent客户端的发送内容，进行解析。
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// // main.c // 震动台server // // Created by ea huang on 2016/7/19. // Copyright © 2018年 ea huang. All rights reserved. // #include <stdio.h> #include <stdlib.h> #include <string.h> #include <arpa/inet.h> #include <sys/types.h> #include <sys/socket.h> #include <unistd.h> #include <fcntl.h> #include <errno.h> #include <sys/time.h> #define DEFAULT_PORT 1921 //默认端口 #define BUFF_SIZE 1024 //buffer大小 #define SELECT_TIMEOUT 5 //select的timeout seconds void parse_socket_buf(char * buf) { if(buf == NULL) { return ; } char delims[] = ","; char *result = NULL; while( (result = strtok( NULL, delims )) != NULL ) { printf( "result is \"%s\"\n", result ); } } //函数：设置sock为non-blocking mode void setSockNonBlock(int sock) { int flags; flags = fcntl(sock, F_GETFL, 0); if (flags < 0) { perror("fcntl(F_GETFL) failed"); exit(EXIT_FAILURE); } if (fcntl(sock, F_SETFL, flags | O_NONBLOCK) < 0) { perror("fcntl(F_SETFL) failed"); exit(EXIT_FAILURE); } } //函数：更新maxfd int updateMaxfd(fd_set fds, int maxfd) { int i; int new_maxfd = 0; for (i = 0; i <= maxfd; i++) { if (FD_ISSET(i, &fds) && i > new_maxfd) { new_maxfd = i; } } return new_maxfd; } int main(int argc, char *argv[]) { unsigned short int port; //获取自定义端口 if (argc == 2) { port = atoi(argv[1]); } else if (argc < 2) { port = DEFAULT_PORT; } else { fprintf(stderr, "USAGE: %s [port]\n", argv[0]); exit(EXIT_FAILURE); } //创建socket int sock; if ( (sock = socket(PF_INET, SOCK_STREAM, 0)) == -1 ) { perror("socket failed, "); exit(EXIT_FAILURE); } printf("socket done\n"); //in case of 'address already in use' error message int yes = 1; if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int))) { perror("setsockopt failed"); exit(EXIT_FAILURE); } //设置sock为non-blocking setSockNonBlock(sock); //创建要bind的socket address struct sockaddr_in bind_addr; memset(&bind_addr, 0, sizeof(bind_addr)); bind_addr.sin_family = AF_INET; bind_addr.sin_addr.s_addr = htonl(INADDR_ANY); //设置接受任意地址 bind_addr.sin_port = htons(port); //将host byte order转换为network byte order //bind sock到创建的socket address上 if ( bind(sock, (struct sockaddr *) &bind_addr, sizeof(bind_addr)) == -1 ) { perror("bind failed, "); exit(EXIT_FAILURE); } printf("bind done\n"); //listen if ( listen(sock, 20) == -1) { perror("listen failed."); exit(EXIT_FAILURE); } printf("listen done\n"); //创建并初始化select需要的参数(这里仅监视read)，并把sock添加到fd_set中 fd_set readfds; fd_set readfds_bak; //backup for readfds(由于每次select之后会更新readfds，因此需要backup) struct timeval timeout; int maxfd; maxfd = sock; FD_ZERO(&readfds); FD_ZERO(&readfds_bak); FD_SET(sock, &readfds_bak); //循环接受client请求 int new_sock; struct sockaddr_in client_addr; socklen_t client_addr_len; char client_ip_str[INET_ADDRSTRLEN]; int res; int i; char buffer[BUFF_SIZE]; long int recv_size; while (1) { //注意select之后readfds和timeout的值都会被修改，因此每次都进行重置 readfds = readfds_bak; maxfd = updateMaxfd(readfds, maxfd); //更新maxfd timeout.tv_sec = SELECT_TIMEOUT; timeout.tv_usec = 0; printf("selecting maxfd=%d\n", maxfd); //select(这里没有设置writefds和errorfds，如有需要可以设置) res = select(maxfd + 1, &readfds, NULL, NULL, &timeout); if (res == -1) { perror("select failed"); exit(EXIT_FAILURE); } else if (res == 0) { fprintf(stderr, "no socket ready for read within %d secs\n", SELECT_TIMEOUT); continue; } //检查每个socket，并进行读(如果是sock则accept) for (i = 0; i <= maxfd; i++) { if (!FD_ISSET(i, &readfds)) { continue; } //可读的socket if ( i == sock) { //当前是server的socket，不进行读写而是accept新连接 client_addr_len = sizeof(client_addr); new_sock = accept(sock, (struct sockaddr *) &client_addr, &client_addr_len); if (new_sock == -1) { perror("accept failed"); exit(EXIT_FAILURE); } if (!inet_ntop(AF_INET, &(client_addr.sin_addr), client_ip_str, sizeof(client_ip_str))) { perror("inet_ntop failed"); exit(EXIT_FAILURE); } printf("accept a client from: %s\n", client_ip_str); //设置new_sock为non-blocking setSockNonBlock(new_sock); //把new_sock添加到select的侦听中 if (new_sock > maxfd) { maxfd = new_sock; } FD_SET(new_sock, &readfds_bak); } else { //当前是client连接的socket，可以写(read from client) memset(buffer, 0, sizeof(buffer)); if ( (recv_size = recv(i, buffer, sizeof(buffer), 0)) == -1 ) { perror("recv failed"); if ( close(i) == -1 ) { perror("close failed"); exit(EXIT_FAILURE); } FD_CLR(i, &readfds_bak); } if((res == 1) && (recv_size == 0)) { //perror("send failed"); printf("res is %d but rcv_sizeis %ld clent off\n",res,recv_size); if ( close(i) == -1 ) { perror("close failed"); exit(EXIT_FAILURE); } FD_CLR(i, &readfds_bak); } printf("recved from new_sock=%d : %s(%ld length string)\n", i, buffer, recv_size); parse_socket_buf(buffer); //立即将收到的内容写回去，并关闭连接 // if ( send(i, buffer, recv_size, 0) == -1 ) // { // perror("send failed"); // close(i); // FD_CLR(i, &readfds_bak); // exit(EXIT_FAILURE); // } /* printf("send to new_sock=%d done\n", i); if ( close(i) == -1 ) { perror("close failed"); exit(EXIT_FAILURE); } printf("close new_sock=%d done\n", i); //将当前的socket从select的侦听中移除 FD_CLR(i, &readfds_bak); */ } } } return 0; } |
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