《UNIX网络编程》TCP客户端服务器：并发、消息回显

/*client_tcp.c*/
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>

#include <netinet/in.h>

#define MAXLINE 4096
#define PORT 12345

void process(FILE *fp, int sockfd)
{
    char send[MAXLINE], recv[MAXLINE];
    while (fgets(send, MAXLINE, fp) != NULL) {
        write(sockfd, send, strlen(send));
        int n = read(sockfd, recv, MAXLINE);
        recv[n] = 0;
        fputs(recv, stdout);
    }
}

int main(int argc, char *argv[])
{
    int sockfd, n;
    char recvline[MAXLINE+1];
    struct sockaddr_in servaddr;

    if (argc != 2) {
        fprintf(stderr, "usage: client_tcp <IP>\n");
        exit(1);
    }

    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        fprintf(stderr, "socket error\n");
        exit(1);
    }

    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) {
        fprintf(stderr, "inet_pton error for %s\n", argv[1]);
        exit(1);
    }

    if (connect(sockfd, (struct sockaddr *) &servaddr,
            sizeof(servaddr)) < 0) {
        fprintf(stderr, "connect error\n");
        exit(1);
    }

    process(stdin, sockfd);

    exit(0);
}

/*server_tcp.c*/
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <netinet/in.h>

#define MAXLINE 4096
#define    LISTENQ 1024
#define PORT 12345

void process(int sockfd)
{
    ssize_t n;
    char buff[MAXLINE+1];

    while ((n = read(sockfd, buff, MAXLINE)) > 0) {
        write(sockfd, buff, n);
    }
}

int main(int argc, char *argv[])
{
    int listenfd, connfd;
    struct sockaddr_in servaddr, cliaddr;
    pid_t pid;

    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(PORT);

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

    listen(listenfd, LISTENQ);

    while (1) {
        int clilen = sizeof(cliaddr);
        connfd = accept(listenfd, (struct sockaddr *)&cliaddr, &clilen);

        if ((pid = fork()) == 0) {//child
            close(listenfd);
            process(connfd);
            exit(0);
        }
        close(connfd);
    }

    exit(0);
}