voiponglfp.c

/*
	VoIPong Voice Over IP Sniffer
	Copyright (C) 2005 Murat Balaban <murat || enderunix.org>
	All rights reserved.

	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 2
	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.




	"Least False Positive" Algorithm
	This will try to catch calls that are compliant with the RTP and RTCP RFCs.
	Note that this algorithm was the default call-catching algorithm prior to
	version 1.2 and may not catch calls that are not RFC-compliant at all.
*/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <netdb.h>
#include <pcap.h>

#include <sys/socket.h>
#include <netinet/in_systm.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define __USE_BSD 1
#define __FAVOR_BSD 1

#include <netinet/ip.h>
#include <netinet/udp.h>
#include <voipong.h>
#include <voipongsock.h>
#include <voipongpcap.h>
#include <voipongvoip.h>
#include <voipongnet.h>
#include <miscutil.h>
#include <conf.h>


extern char gdevice[256];
extern char gfilter[1024];
extern int gpromisc;
extern int gsnaplen;
extern int greadtmt;

void
packet_handler_lfp(vnet *v, u_char *udata, const struct pcap_pkthdr *pkthdr, const u_char *packet)
{
	struct ip *ip;
	struct udphdr *udp;
	short iphlen = 0;

	ip = (struct ip *)packet;
	iphlen = ip->ip_hl << 2;
	if (ip->ip_p != IPPROTO_UDP)
		return;
	udp = (struct udphdr *)(packet + iphlen);
	if (isodd(ntohs(udp->uh_sport)) && isodd(ntohs(udp->uh_dport)))
		probertcp(udata, pkthdr, packet);
	else
	if (iseven(ntohs(udp->uh_sport)) && iseven(ntohs(udp->uh_dport)))
		probertp(udata, pkthdr, packet);
}