#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <sys/timeb.h>
#include <string.h>

#define BYTES_NR 64
#define MSG_NR 512


char buf[BYTES_NR];

int main(int argc,char *argv[]) 
{
  int  sock;
  socklen_t length;
  struct   sockaddr_in   server,client;
  int  rval,i;
  struct  hostent  *hp,*gethostbyname();

  if(argc !=2)
  {
    fprintf(stderr,"Usage: %s port\n",argv[0]);
    exit(-1);
  }

  /* Create socket */
  sock = socket(AF_INET,SOCK_DGRAM,0);
  if(sock<0)
  {
    perror("opening stream socket");
    exit(1);
  }

  /* Name socket using wildcards */
  server.sin_family =   AF_INET;
  server.sin_addr.s_addr= INADDR_ANY;
  server.sin_port = htons(atoi(argv[1]));
  if (bind(sock,(struct sockaddr *)&server,sizeof server)<0)
  {
    perror("binding stream socket");
    exit(1);
  }

  /* Find out assigned port and print out */
  length= sizeof server;
  if(getsockname(sock,(struct sockaddr *)&server,&length)<0)
  {
    perror("getting socket name");
    exit(1);
  }

  printf("Socket port #%d\n",ntohs(server.sin_port));
  hp = gethostbyname(argv[1]);
  if (hp == 0)
  {
    fprintf(stderr,"%s :unknow host",argv[1]);
    exit(2);
  }
  bcopy( (char *)hp ->h_addr, (char *)&client.sin_addr,hp ->h_length);

  while(1)
  {
    do
    {
      bzero(buf,sizeof buf);
      if((rval = recvfrom(sock,buf,sizeof buf, 0, (struct sockaddr *)&client, (socklen_t *)&length ))<0)
        perror("reading stream message");
      i=0;
      if(rval==0)
        printf("Ending connection\n");
      else 
      {
        printf("Message received: sending back\n");
        strcat(buf,"*");
        if(sendto(sock,buf,sizeof buf,0,(struct sockaddr *)&client,sizeof client)<0)
          perror("writing on stream socket");
      }
    } while(rval !=0);
  }
  return 0;
}