#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <ulimit.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <string.h>

#include "packets.h" 
#define MAXFILES 20

void fatal_error(char *err_msg)
{
  fprintf(stderr,"%s\n",err_msg);
  exit(0);
}

void free_buffer (void *buffer)   
{
  free(buffer);
}

void send_buffer (int to_socket, void *buffer, int length) 
{
  int result, sent;

  for (sent = 0; sent < length; )
    {
      result = write(to_socket, buffer + sent, length - sent); 
      if (result < 0 && errno != EINTR)   
        fatal_error("Can't send packet");   
      if (!result) break;
      sent += result;
    }

  if (sent != length) 
    fatal_error("Can't send complete packet");   
}

void send_packet (int to_socket, void *packet, unsigned short int length)
{
  short int l = htons(length);
  send_buffer(to_socket,&l,sizeof(short int)); 
  send_buffer(to_socket,packet,length); 
}

void send_string (int to_socket, char *str)
{
  send_packet(to_socket,str,strlen(str)+1);
}

void wait_for_packet(int from_socket)   
{
  fd_set readfds;
  int result;

  for (;;)
    {
      FD_ZERO(&readfds);
      FD_SET(from_socket, &readfds);

      result = select(MAXFILES, &readfds, NULL, NULL, NULL);

      if (result < 0 && errno != EINTR)
        fatal_error("Can't wait for msg");

      if (FD_ISSET(from_socket,&readfds))   
        break;
    }
}

void receive_buffer (int from_socket, void *buffer, int length)
{
  int result,rcvd;

  for (rcvd = 0; rcvd < length; )
    {
      wait_for_packet(from_socket);
      result = read(from_socket, buffer + rcvd, length - rcvd); 
      if (result < 0 && errno != EINTR)
        fatal_error("Can't receive packet");
      if (!result) break;

      rcvd += result;
    }

  if (rcvd != length)
    fatal_error("Got incomplete packet");
}

unsigned short int receive_packet (int from_socket, void **buffer)
{
  unsigned short int length;
  receive_buffer(from_socket, &length, sizeof(short int));
  length = ntohs(length);
  *buffer = malloc(length);
  receive_buffer(from_socket, *buffer, length);
  return length;
}