#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define MYPORT 4950    // the port users will be connecting to

#define MYPORT2 4951
#define MAXBUFLEN 100

int main()
{
  int sockfd, sockfd_forward,i,j;
  struct sockaddr_in my_addr;    // my address information
  struct sockaddr_in their_addr; // connector's address information
  int addr_len, numbytes;
  char buf[MAXBUFLEN];
  char address[MAXBUFLEN];
  char msg[MAXBUFLEN];
  struct sockaddr_in their_addr_forward; // destination's address information
  struct hostent *h;

  if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
        perror("socket");
        exit(1);
  }

  if ((sockfd_forward = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
    perror("socket");
    exit(1);
  }

  my_addr.sin_family = AF_INET;         // host byte order
  my_addr.sin_port = htons(MYPORT);     // short, network byte order
  my_addr.sin_addr.s_addr = INADDR_ANY; // automatically fill with my IP
  memset(&(my_addr.sin_zero), '\0', 8); // zero the rest of the struct

  if (bind(sockfd, (struct sockaddr *)&my_addr,
	   sizeof(struct sockaddr)) == -1) {
    perror("bind");
    exit(1);
  }

  addr_len = sizeof(struct sockaddr);
  if ((numbytes=recvfrom(sockfd, buf, MAXBUFLEN-1 , 0,
			 (struct sockaddr *)&their_addr, &addr_len)) == -1) {
    perror("recvfrom");
    exit(1);
  }

  printf("got packet from %s\n",inet_ntoa(their_addr.sin_addr));
  printf ("packet is %d bytes long\n",numbytes);
  buf[numbytes] = '\0';

  for(i=0;buf[i]!='+';i++)
    {
      address[i]=buf[i];
    }
  address[i]='\0';

  j=i+1;
  i=0;
  for(;j<numbytes;j++)
    msg[i++]=buf[j];
  msg[i]='\0';

  printf("packet contains \"%s\"\n",buf);
  close(sockfd);


  if (bind(sockfd_forward, (struct sockaddr *)&my_addr,
	   sizeof(struct sockaddr)) == -1) {
    perror("bind");
    exit(1);
  }

  if ((h=gethostbyname(address))==NULL) {  // get the host info
    herror("gethostbyname");
    exit(1);
  }

  their_addr_forward.sin_family = AF_INET;
  their_addr_forward.sin_port=htons(MYPORT2);

  their_addr_forward.sin_addr = *((struct in_addr *)h->h_addr);
  memset(&(their_addr_forward.sin_zero), '\0', 8);

  if ((numbytes=sendto(sockfd_forward, msg, strlen(msg), 0,
		       (struct sockaddr *)&their_addr_forward, sizeof(struct sockaddr))) == -1) {
    perror("sendto");
    exit(1);
  }

  printf("Sent message to Host name  : %s\n", h->h_name);
  printf("IP Address : %s\n", inet_ntoa(*((struct in_addr *)h->h_addr)));

  //close(sockfd);
  close(sockfd_forward);
  return 0;
}