#include "unp.h"

void str_echo(int); 

void sig_chld(int);

int main(int argc, char *argv[])
{
    int     listenfd, confd;
    pid_t   childpid;
    socklen_t clilen;
    struct sockaddr_in cliaddr, servaddr;

    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(SERV_PORT);
    Bind(listenfd, (SA *)&servaddr, sizeof(servaddr));
    Listen(listenfd, LISTENQ);
    Signal(SIGCHLD, sig_chld);
    for(;;) {
        clilen = sizeof(cliaddr);
        if((confd = accept(listenfd, (SA *) &cliaddr, &clilen))< 0 ) {
            if (errno == EINTR) 
                continue; // back to for()
            else 
                err_sys("accept error");
        }
        if((childpid = Fork()) == 0) { // child process 
            Close(listenfd); // close listening socket
            str_echo(confd);
            exit(0);
        }
        Close(confd); // parent close connected socket
    }

}

void str_echo(int sockfd)
{
    ssize_t     n;
    char        buf[MAXLINE];

again:
    while((n = read(sockfd, buf, MAXLINE)) > 0)
        Writen(sockfd, buf, n);

    if(n < 0 && errno == EINTR)
        goto again;
    else if (n < 0)
        err_sys("str echo: read error");
}

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

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