#include        <sys/types.h>   /* basic system data types */
#include        <sys/socket.h>  /* basic socket definitions */
#include	<netinet/in.h>
#include 	<stdio.h>
#include	<unistd.h>
#include	<strings.h>
#include	<stdlib.h>

#define MAXLINE 1024
#define LISTENQ 16    /* max size of queue */

ssize_t
readline(int fd, void *vptr, size_t maxlen)
{
  int n, rc;
  char c, *ptr;

  ptr = vptr;
  for (n = 1; n < maxlen; n++) {
    if ( (rc = read(fd, &c, 1)) == 1) {
      *ptr++ = c;
      if (c == '\n')
	break;  /* newline is stored, like fgets() */
    } else if (rc == 0) {
      if (n == 1)
	return(0);      /* EOF, no data read */
      else
	break;          /* EOF, some data was read */
    } else
      return(-1);             /* error, errno set by read() */
  }
  
  *ptr = 0;       /* null terminate like fgets() */
  return(n);
} /* end readline */


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

  for ( ; ; ) {
    if ( (n = readline(sockfd, line, MAXLINE)) == 0)
      return;         /* connection closed by other end */
    
    write(sockfd, line, n);
  }
} /* end str_echo */


int
main(int argc, char **argv)
{
  int			listenfd, connfd;
//  pid_t			childpid;
  int		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(6789);

  if(bind(listenfd, (struct sockaddr *) &servaddr, sizeof(servaddr)))
	{
	printf("Bind failed.\n");
//	exit(-1);
	}

  if (listen(listenfd, LISTENQ) == -1)
  {
	printf("Listen failed\n");
//	exit(-1);
  }

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

    str_echo(connfd);	/* process the request */
    close(connfd);		/* close connected socket */
  }
} /* end main */