Linux Socket C/S 通信问题

main(int argc, char **argv )

{ 
    int listenfd, connfd; 
    pid_t childpid; 

    struct sockaddr_in servaddr, cliaddr; 
    socklen_t clilen; 

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

    Listen( listenfd, 10 ); 

    for ( ; ; ) { 
        clilen = sizeof( cliaddr ); 
        
        connfd = Accept( listenfd, ( struct sockaddr * ) &cliaddr, &clilen ); 
        if ( ( childpid = Fork( ) ) == 0 ) { 
            close( listenfd ); 
            str_echo( connfd ); 
            exit( 0 ); 
        } 
        close( connfd ); 
    } 
} 

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

again: 
    while ( ( n = read( sockfd,buf, MAXLINE ) ) > 0 ) { 
        write( sockfd, buf, n ); 
    } 
    if ( n < 0 && errno == EINTR ) 
        goto again; 
    else if ( n < 0 ) 
        printf( "str_echo error\n " ); 
    
}