/* to compile do: gcc -g -o server server.c -lsocket -lnsl */

#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>

int main(int argc, char **argv)
{
   int sockfd, i, j, n, loss, size, val, flag, port, count, delay;
   struct sockaddr_in servaddr,cliaddr;
   float floss;
   socklen_t len;
   unsigned char init[101], filename[11], client[21];
   unsigned short *mesg;
   FILE *fpi;

   if (argc != 2) {
     printf ("\nusage: exec <port> \n");
     exit (0);
   }
   sockfd=socket(AF_INET,SOCK_DGRAM,0);
 
   bzero(&servaddr,sizeof(servaddr));
   servaddr.sin_family = AF_INET;
   servaddr.sin_addr.s_addr=htonl(INADDR_ANY);
   servaddr.sin_port=htons(atoi(argv[1]));
   bind(sockfd,(struct sockaddr *)&servaddr,sizeof(servaddr));
   
   for (i = 0; i < 101; i++) { init[i] = 0; }
   for (;;) {
     flag = 0;
     n = recvfrom (sockfd, init, 100*sizeof(char), 0, (struct sockaddr *) &cliaddr, &len);
     printf ("\n%s\n", init);
     sscanf (init, "%s %d %s %d %f", client, &port, filename, &size, &floss);
     strcat (filename, ".au");
     printf ("\n----------------------------------\n");
     loss = (int) (100*floss);
     printf ("\nThe client IPaddess : %s", client);
     printf ("\nThe port number : %d", port);
     printf ("\nThe requested file : %s", filename);
     printf ("\nThe size of each datagram : %d", size);
     printf ("\nThe loss percentage : %d", loss);
     printf ("\n\nSending "); 
     delay = (int)(1000*size/8);
     mesg = (unsigned short *) malloc (sizeof (unsigned short)*size);
     if ((fpi = fopen(filename, "r")) != NULL)  flag = 1;
     else flag = 0;
     if (flag == 1) {
       count = 0;
       while (fread (mesg, sizeof (unsigned short), size, fpi) != '\0') {
	 val = 1 + (int)(100.0*rand()/(RAND_MAX + 1.0));
	 if ((loss < val) || (count == 0)) {
	   sendto (sockfd, mesg, size*sizeof(unsigned short), 0, (struct sockaddr *)&cliaddr, sizeof(cliaddr));
	   for (i = 0; i < size; i++) { mesg[i] = 0; }
	 }
	 else {
	   for (i = 0; i < size; i++) { mesg[i] = 0; }
	   /*sendto (sockfd, mesg, size*sizeof(unsigned short), 0, (struct 
sockaddr *)&cliaddr, sizeof(cliaddr));*/
	 }
	 count++;
	 printf (".");
	 usleep(delay);
       }
       fclose (fpi);
       sendto (sockfd, NULL, sizeof(unsigned char), 0, (struct sockaddr *) &cliaddr, sizeof(cliaddr));
       printf ("\nSent last packet .. \n");
       break;
     }
     else {
       continue;
     }
   }
   printf ("\n\n\n\n");
   return 0;
}