Linux网络编程（一）：一个简单的socket程序

服务器：

 /*
  *tcp_server.c
  */

 #include <stdio.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include <string.h>
 #include <errno.h>
 #include <stdlib.h>
 #include <signal.h>

 #define SER_PORT 8000
 #define MAX_LINE 1024

 void str_echo(int sockfd);
 void sig_chld(int signo);

 int main(int argc, char **argv)
 {
     int listenfd, connfd;
     struct sockaddr_in servaddr, cliaddr;
     socklen_t cliaddr_len;
     char buff[MAX_LINE];
     pid_t childpid;

     listenfd = socket(AF_INET, SOCK_STREAM, );

     bzero(&servaddr, sizeof(servaddr));
     servaddr.sin_family = AF_INET;
     servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
     servaddr.sin_port = htons(SER_PORT);

     bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr));

     listen(listenfd, );
     signal(SIGCHLD, sig_chld);

     while()
     {
         cliaddr_len = sizeof(cliaddr);
         connfd = accept(listenfd, (struct sockaddr *)&cliaddr, &cliaddr_len);
         printf("receive from %s at port %d\n", inet_ntop(AF_INET, &cliaddr.sin_addr, buff, sizeof(buff)), ntohs(cliaddr.sin_port));

         if ((childpid = fork()) == ) /* child process */
         {
             printf("child process pid = %d\n", (int)childpid);
             close(listenfd);
             str_echo(connfd);
             printf("child process terminated\n");
             exit();
         }

         close(connfd);
     }

     return ;
 }

 void str_echo(int sockfd)
 {
     ssize_t n;
     char buf[MAX_LINE] = {};

 AGAIN:
     while ((n = read(sockfd, buf, MAX_LINE)) > )
     {
         printf("%s\n", buf);
         write(sockfd, buf, n);
         bzero(buf, sizeof(buf));
     }

     if (n <  && errno == EINTR)
     {
         goto AGAIN;
     }
     else if (n < )
     {
         printf("read error\n");
     }
     else
     {
         printf("str_echo: read EOF\n");
     }

 }

 void sig_chld(int signo)
 {
     pid_t pid;
     int stat;

     pid = wait(&stat);
     printf("child %d terminated\n", pid);

     return;
 }

客户端：

 /*
  *tcp_client.c
  */

 #include <stdio.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include <errno.h>
 #include <string.h>

 #define SER_PORT 8000
 #define MAX_LINE 1024

 void str_cli(FILE *fp, int sockfd);

 int main(int argc, char **argv)
 {
     int sockfd;
     struct sockaddr_in servaddr;

     sockfd = socket(AF_INET, SOCK_STREAM, );

     bzero(&servaddr, sizeof(servaddr));
     servaddr.sin_family = AF_INET;
     inet_pton(AF_INET, "127.0.0.1", &servaddr.sin_addr);
     servaddr.sin_port = htons(SER_PORT);

     if(connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) < )
     {
         printf("connect error:%s\n", strerror(errno));
         return ;
     }

     str_cli(stdin, sockfd);

     return ;
 }

 void str_cli(FILE *fp, int sockfd)
 {
     char sendline[MAX_LINE] = {};
     char recvline[MAX_LINE] = {};

     while (fgets(sendline, MAX_LINE, fp) != NULL)
     {
         write(sockfd, sendline, strlen(sendline));

         if (read(sockfd, recvline, MAX_LINE) == )
         {
             printf("server terminated\n");
             break;
         }
         fputs(recvline, stdout);

         bzero(sendline, sizeof(sendline));
         bzero(recvline, sizeof(recvline));
     }
 }

参考：

《UNIX网络编程 - 卷1：套接字联网API》