Linux Socket C语言网络编程：Select Socket

Select Socket

结果

$ ./server &$ ./client 127.0.0.1accpet connection~accpet a new client: 127.0.0.1:23261this is a test.reading the socket~~~ clint[0] send message: this is a test.this is a test.

当然，你也可以再打开一个终端，然后运行客户端代码，结果在本文的最后部分

服务器代码server.c

#include <stdio.h>#include <stdlib.h>#include <string.h>#include <errno.h>#include <unistd.h>#include <time.h>#include <sys/socket.h>#include <sys/select.h>#include <sys/types.h>#include <netinet/in.h>#include <arpa/inet.h>#include <netdb.h>#include <fcntl.h>#define PORT 8888#define MAX_LINE 2048#define LISTENQ 20int main(int argc , char **argv){int i, maxi, maxfd, listenfd, connfd, sockfd;int nready , client[FD_SETSIZE];ssize_t n, ret;fd_set rset , allset;char buf[MAX_LINE];socklen_t clilen;struct sockaddr_in servaddr , cliaddr;/*(1) 得到监听描述符*/listenfd = socket(AF_INET , SOCK_STREAM , 0);/*(2) 绑定套接字*/bzero(&servaddr , sizeof(servaddr));servaddr.sin_family = AF_INET;servaddr.sin_addr.s_addr = htonl(INADDR_ANY);servaddr.sin_port = htons(PORT);bind(listenfd , (struct sockaddr *)&servaddr , sizeof(servaddr));/*(3) 监听*/listen(listenfd , LISTENQ);/*(4) 设置select*/maxfd = listenfd;maxi = -1;for(i=0 ; i<FD_SETSIZE ; ++i){client[i] = -1;}//forFD_ZERO(&allset);FD_SET(listenfd , &allset);/*(5) 进入服务器接收请求死循环*/while(1){rset = allset;nready = select(maxfd+1 , &rset , NULL , NULL , NULL);if(FD_ISSET(listenfd , &rset)){/*接收客户端的请求*/clilen = sizeof(cliaddr);printf("\naccpet connection~\n");if((connfd = accept(listenfd , (struct sockaddr *)&cliaddr , &clilen)) < 0){perror("accept error.\n");exit(1);}//ifprintf("accpet a new client: %s:%d\n", inet_ntoa(cliaddr.sin_addr) , cliaddr.sin_port);/*将客户链接套接字描述符添加到数组*/for(i=0 ; i<FD_SETSIZE ; ++i){if(client[i] < 0){client[i] = connfd;break;}//if}//forif(FD_SETSIZE == i){perror("too many connection.\n");exit(1);}//ifFD_SET(connfd , &allset);if(connfd > maxfd)maxfd = connfd;if(i > maxi)maxi = i;if(--nready < 0)continue;}//iffor(i=0; i<=maxi ; ++i){if((sockfd = client[i]) < 0)continue;if(FD_ISSET(sockfd , &rset)){/*处理客户请求*/printf("\nreading the socket~~~ \n");bzero(buf , MAX_LINE);if((n = read(sockfd , buf , MAX_LINE)) <= 0){close(sockfd);FD_CLR(sockfd , &allset);client[i] = -1;}//ifelse{printf("clint[%d] send message: %s\n", i , buf);if((ret = write(sockfd , buf , n)) != n){printf("error writing to the sockfd!\n");break;}//if}//elseif(--nready <= 0)break;}//if}//for}//while}

客户端代码client.c

#include <stdio.h>#include <stdlib.h>#include <string.h>#include <errno.h>#include <unistd.h>#include <time.h>#include <sys/socket.h>#include <sys/select.h>#include <sys/types.h>#include <netinet/in.h>#include <arpa/inet.h>#include <netdb.h>#include <fcntl.h>#define PORT 8888#define MAX_LINE 2048int max(int a , int b){return a > b ? a : b;}/*readline函数实现*/ssize_t readline(int fd, char *vptr, size_t maxlen){ssize_tn, rc;charc, *ptr;ptr = vptr;for (n = 1; n < maxlen; n++) {if ( (rc = read(fd, &c,1)) == 1) {*ptr++ = c;if (c == '\n')break;/* newline is stored, like fgets() */} else if (rc == 0) {*ptr = 0;return(n - 1);/* EOF, n - 1 bytes were read */} elsereturn(-1);/* error, errno set by read() */}*ptr = 0;/* null terminate like fgets() */return(n);}/*普通客户端消息处理函数*/void str_cli(int sockfd){/*发送和接收缓冲区*/char sendline[MAX_LINE] , recvline[MAX_LINE];while(fgets(sendline , MAX_LINE , stdin) != NULL){write(sockfd , sendline , strlen(sendline));bzero(recvline , MAX_LINE);if(readline(sockfd , recvline , MAX_LINE) == 0){perror("server terminated prematurely");exit(1);}//ifif(fputs(recvline , stdout) == EOF){perror("fputs error");exit(1);}//ifbzero(sendline , MAX_LINE);}//while}/*采用select的客户端消息处理函数*/void str_cli2(FILE* fp , int sockfd){int maxfd;fd_set rset;/*发送和接收缓冲区*/char sendline[MAX_LINE] , recvline[MAX_LINE];FD_ZERO(&rset);while(1){/*将文件描述符和套接字描述符添加到rset描述符集*/FD_SET(fileno(fp) , &rset);FD_SET(sockfd , &rset);maxfd = max(fileno(fp) , sockfd) + 1;select(maxfd , &rset , NULL , NULL , NULL);if(FD_ISSET(fileno(fp) , &rset)){if(fgets(sendline , MAX_LINE , fp) == NULL){printf("read nothing~\n");close(sockfd); /*all done*/return ;}//ifsendline[strlen(sendline) - 1] = '\0';write(sockfd , sendline , strlen(sendline));}//ifif(FD_ISSET(sockfd , &rset)){if(readline(sockfd , recvline , MAX_LINE) == 0){perror("handleMsg: server terminated prematurely.\n");exit(1);}//ifif(fputs(recvline , stdout) == EOF){perror("fputs error");exit(1);}//if}//if}//while}int main(int argc , char **argv){/*声明套接字和链接服务器地址*/int sockfd;struct sockaddr_in servaddr;/*判断是否为合法输入*/if(argc != 2){perror("usage:tcpcli <IPaddress>");exit(1);}//if/*(1) 创建套接字*/if((sockfd = socket(AF_INET , SOCK_STREAM , 0)) == -1){perror("socket error");exit(1);}//if/*(2) 设置链接服务器地址结构*/bzero(&servaddr , sizeof(servaddr));servaddr.sin_family = AF_INET;servaddr.sin_port = htons(PORT);if(inet_pton(AF_INET , argv[1] , &servaddr.sin_addr) < 0){printf("inet_pton error for %s\n",argv[1]);exit(1);}//if/*(3) 发送链接服务器请求*/if(connect(sockfd , (struct sockaddr *)&servaddr , sizeof(servaddr)) < 0){perror("connect error");exit(1);}//if/*调用普通消息处理函数*/str_cli(sockfd);/*调用采用select技术的消息处理函数*///str_cli2(stdin , sockfd);exit(0);}

Makefile

ALL:gcc server.c -o server -lmgcc client.c -o client -lm

在不同的终端下测试的结果：