/*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] = ;
        fputs(recv, stdout);
    }
}

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

    ) {
        fprintf(stderr, "usage: client_tcp <IP>\n");
        exit();
    }

    )) < ) {
        fprintf(stderr, "socket error\n");
        exit();
    }

    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(PORT);
    ], &servaddr.sin_addr) <= ) {
        fprintf(stderr, ]);
        exit();
    }

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

    process(stdin, sockfd);

    exit();
}

/*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;
    ];

    ) {
        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, );

    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);

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

        ) {//child
            close(listenfd);
            process(connfd);
            exit();
        }
        close(connfd);
    }

    exit();
}