PcapInterface.cpp

/*
 *
 * (C) 2013 - ntop.org
 *
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 */

#include "ntop_includes.h"

#ifdef __APPLE__
#include <uuid/uuid.h>
#endif

/* **************************************************** */

PcapInterface::PcapInterface(const char *name) : NetworkInterface(name) {
  char pcap_error_buffer[PCAP_ERRBUF_SIZE];

  if((pcap_handle = pcap_open_live(ifname, ntop->getGlobals()->getSnaplen(),
				   ntop->getGlobals()->getPromiscuousMode(),
				   500, pcap_error_buffer)) == NULL) {
    pcap_handle = pcap_open_offline(ifname, pcap_error_buffer);

    if(pcap_handle == NULL) {
      printf("ERROR: could not open pcap file: %s\n", pcap_error_buffer);
      exit(0);
    } else {
      char *slash = strrchr(ifname, '/');

      if(slash) {
	char *old = ifname;
	ifname = strdup(&slash[1]);
	free(old);
      }

      ntop->getTrace()->traceEvent(TRACE_NORMAL, "Reading packets from pcap file %s...", ifname);
      read_pkts_from_pcap_dump = true, purge_idle_flows_hosts = false;
    }
  } else {
    ntop->getTrace()->traceEvent(TRACE_NORMAL, "Reading packets from interface %s...", ifname);
    read_pkts_from_pcap_dump = false;
  }

  pcap_datalink_type = pcap_datalink(pcap_handle);
}

/* **************************************************** */

PcapInterface::~PcapInterface() {
  shutdown();

  if(pcap_handle)
    pcap_close(pcap_handle);

  deleteDataStructures();
}

/* **************************************************** */

static void* packetPollLoop(void* ptr) {
  PcapInterface *iface = (PcapInterface*)ptr;
  pcap_t  *pd = iface->get_pcap_handle();

  /* Wait until the initialization competes */
  while(!iface->isRunning()) sleep(1);

  while(iface->isRunning() 
	&& (!ntop->getGlobals()->isShutdown())) {
    const u_char *pkt;
    struct pcap_pkthdr hdr;

    if((pkt = pcap_next(pd, &hdr)) != NULL) {
      if((hdr.caplen > 0) && (hdr.len > 0))
	iface->packet_dissector(&hdr, pkt);
    } else {
      if(iface->read_from_pcap_dump())
	break;

      iface->purgeIdle(time(NULL));
    }
  } /* while */

  ntop->getTrace()->traceEvent(TRACE_NORMAL, "Terminated packet polling for %s", iface->get_name());
  return(NULL);
}

/* **************************************************** */

void PcapInterface::startPacketPolling() {
  pthread_create(&pollLoop, NULL, packetPollLoop, (void*)this);
  NetworkInterface::startPacketPolling();
}

/* **************************************************** */

void PcapInterface::shutdown() {
  if(running) {
    void *res;

    NetworkInterface::shutdown();
    if(pcap_handle) pcap_breakloop(pcap_handle);
    pthread_join(pollLoop, &res);
  }
}

/* **************************************************** */

u_int PcapInterface::getNumDroppedPackets() {
  struct pcap_stat pcapStat;

  if(pcap_stats(pcap_handle, &pcapStat) >= 0) {
    return(pcapStat.ps_drop);
  } else
    return(0);
}

/* **************************************************** */

bool PcapInterface::set_packet_filter(char *filter) {
  struct bpf_program fcode;
  struct in_addr netmask;

  netmask.s_addr = htonl(0xFFFFFF00);

  if((pcap_compile(pcap_handle, &fcode, filter, 1, netmask.s_addr) < 0)
     || (pcap_setfilter(pcap_handle, &fcode) < 0)) {
    ntop->getTrace()->traceEvent(TRACE_ERROR, "Unable to set filter %s. Filter ignored.\n", filter);
    return(false);
  } else {
    ntop->getTrace()->traceEvent(TRACE_NORMAL, "Packet capture filter set to \"%s\"", filter);
    return(true);
  }
};