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, 0);
    
    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, 20);
    signal(SIGCHLD, sig_chld);
    
    while(1)
    {
        cliaddr_len = sizeof(cliaddr);
        connfd = accept(listenfd, (struct sockaddr *)&cliaddr, &cliaddr_len);
        printf("receive from %s at port %d
", inet_ntop(AF_INET, &cliaddr.sin_addr, buff, sizeof(buff)), ntohs(cliaddr.sin_port));
        
        if ((childpid = fork()) == 0) /* child process */
        {
            printf("child process pid = %d
", (int)childpid);
            close(listenfd);
            str_echo(connfd);
            printf("child process terminated
");
            exit(0);
        }
        
        close(connfd);
    }

    return 0;
}

void str_echo(int sockfd)
{
    ssize_t n;
    char buf[MAX_LINE] = {0};

AGAIN:
    while ((n = read(sockfd, buf, MAX_LINE)) > 0)
    {
        printf("%s
", buf);
        write(sockfd, buf, n);
        bzero(buf, sizeof(buf));
    }
    
    if (n < 0 && errno == EINTR)
    {
        goto AGAIN;
    }
    else if (n < 0)
    {
        printf("read error
");
    }
    else
    {
        printf("str_echo: read EOF
");
    }
    
}

void sig_chld(int signo)
{
    pid_t pid;
    int stat;
    
    pid = wait(&stat);
    printf("child %d terminated
", 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, 0);

    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)) < 0)
    {
        printf("connect error:%s
", strerror(errno));
        return 0;
    }
    
    str_cli(stdin, sockfd);
    
    return 0;
}

void str_cli(FILE *fp, int sockfd)
{
    char sendline[MAX_LINE] = {0};
    char recvline[MAX_LINE] = {0};

        
    while (fgets(sendline, MAX_LINE, fp) != NULL)
    {
        write(sockfd, sendline, strlen(sendline));
        
        if (read(sockfd, recvline, MAX_LINE) == 0)
        {
            printf("server terminated
");
            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》