#include "pcap-thread.h"
#include "rssi_list.h"
#include <semaphore.h>
#include <signal.h>
#include<pcap.h>



extern volatile sig_atomic_t got_sigint;
extern Element * rssi_list;
extern sem_t synchro;

void *pcap_function(void *arg)
{
  char *iface = (char *) arg;
  char errbuf[PCAP_ERROR_BUFFER_SIZE];
  struct pcap_t * handle = NULL;
  struct ieee80211_radiotap_header * rtap_head;
  struct ieee80211_header * eh;
  struct pcap_pkthdr header;
  const u_char * packet;
  u_char * mac;
  u_char first_flags;
  int offset = 0;
  char rssi;
  Element * dev_info;

  // Open pcap handle to sniff traffic
  handle = pcap_open_live(iface, BUFSIZ, 1, 1000, errbuf);
  if (handle == NULL) {
    printf("Could not open pcap on %s\n", iface);
    pthread_exit((void *) -1);
  }
  
  while (got_sigint == 0) {
    packet = pcap_next(handle, &header);
    if (!packet)
      continue;
    rtap_head = (struct ieee80211_radiotap_header *) packet;
    int len = (int) rtap_head->it_len[0] + 256 * (int) rtap_head->it_len[1];
    eh = (struct ieee80211_header *) (packet + len);
    if ((eh->frame_control & 0x03) == 0x01) {
      mac = eh->source_addr;
      first_flags = rtap_head->it_present[0];
      offset = 8;
      offset += ((first_flags & 0x01) == 0x01) ? 8 : 0 ;
      offset += ((first_flags & 0x02) == 0x02) ? 1 : 0 ;
      offset += ((first_flags & 0x04) == 0x04) ? 1 : 0 ;
      offset += ((first_flags & 0x08) == 0x08) ? 4 : 0 ;
      offset += ((first_flags & 0x10) == 0x10) ? 2 : 0 ;
      rssi = *((char *) rtap_head + offset) - 0x100;
      //printf("%d bytes -- %02X:%02X:%02X:%02X:%02X:%02X -- RSSI: %d dBm\n",
      //       len, mac[0], mac[1], mac[2], mac[3], mac[4], mac[5], (int) rssi);
      // We got some message issued by a terminal (FromDS=0,ToDS=1)
      sem_wait(&synchro);
      if ((dev_info = find_mac(rssi_list, mac)) == NULL) {
		dev_info = add_element(&rssi_list, mac);
      }
      clear_outdated_values(dev_info->measurements);
      add_value(dev_info->measurements, (int) rssi);
      sem_post(&synchro);
    }
  }
  pcap_close(handle);
  pthread_exit((void *) 0);
}