/*
* 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
*
* Author : Guillaume TEISSIER from FTR&D 02/02/2006
*/
#include <pcap.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <netinet/udp.h>
#if defined(__HPUX) || defined(__CYGWIN) || defined(__FreeBSD__)
#include <netinet/in_systm.h>
#endif
#include <netinet/ip.h>
#ifndef __CYGWIN
#include <netinet/ip6.h>
#endif
#include <string.h>
#include "prepare_pcap.h"
#include "screen.hpp"
/* We define our own structures for Ethernet Header and IPv6 Header as they are not available on CYGWIN.
* We only need the fields, which are necessary to determine the type of the next header.
* we could also define our own structures for UDP and IPv4. We currently use the structures
* made available by the platform, as we had no problems to get them on all supported platforms.
*/
typedef struct _ether_hdr {
char ether_dst[6];
char ether_src[6];
u_int16_t ether_type; /* we only need the type, so we can determine, if the next header is IPv4 or IPv6 */
} ether_hdr;
typedef struct _ipv6_hdr {
char dontcare[6];
u_int8_t nxt_header; /* we only need the next header, so we can determine, if the next header is UDP or not */
char dontcare2[33];
} ipv6_hdr;
#ifdef __HPUX
int check(u_int16_t *buffer, int len){
#else
inline int check(u_int16_t *buffer, int len){
#endif
int sum;
int i;
sum = 0;
for (i=0; i<(len&~1); i+= 2)
sum += *buffer++;
if (len & 1) {
sum += htons( (*(const u_int8_t *)buffer) << 8);
}
return sum;
}
#ifdef __HPUX
u_int16_t checksum_carry(int s) {
#else
inline u_int16_t checksum_carry(int s) {
#endif
int s_c = (s >> 16) + (s & 0xffff);
return (~(s_c + (s_c >> 16)) & 0xffff);
}
char errbuf[PCAP_ERRBUF_SIZE];
/* prepare a pcap file
*/
int prepare_pkts(char *file, pcap_pkts *pkts) {
pcap_t *pcap;
struct pcap_pkthdr *pkthdr = NULL;
u_char *pktdata = NULL;
int n_pkts = 0;
u_long max_length = 0;
u_int16_t base = 0xffff;
u_long pktlen;
pcap_pkt *pkt_index;
ether_hdr *ethhdr;
struct iphdr *iphdr;
ipv6_hdr *ip6hdr;
struct udphdr *udphdr;
pkts->pkts = NULL;
pcap = pcap_open_offline(file, errbuf);
if (!pcap)
ERROR("Can't open PCAP file '%s'", file);
#if HAVE_PCAP_NEXT_EX
while (pcap_next_ex (pcap, &pkthdr, (const u_char **) &pktdata) == 1)
{
#else
#ifdef __HPUX
pkthdr = (pcap_pkthdr *) malloc (sizeof (*pkthdr));
#else
pkthdr = malloc (sizeof (*pkthdr));
#endif
if (!pkthdr)
ERROR("Can't allocate memory for pcap pkthdr");
while ((pktdata = (u_char *) pcap_next (pcap, pkthdr)) != NULL)
{
#endif
ethhdr = (ether_hdr *)pktdata;
if (ntohs(ethhdr->ether_type) != 0x0800 /* IPv4 */
&& ntohs(ethhdr->ether_type) != 0x86dd) /* IPv6 */ {
fprintf(stderr, "Ignoring non IP{4,6} packet!\n");
continue;
}
iphdr = (struct iphdr *)((char *)ethhdr + sizeof(*ethhdr));
if (iphdr && iphdr->version == 6) {
//ipv6
pktlen = (u_long) pkthdr->len - sizeof(*ethhdr) - sizeof(*ip6hdr);
ip6hdr = (ipv6_hdr *)(void *) iphdr;
if (ip6hdr->nxt_header != IPPROTO_UDP) {
fprintf(stderr, "prepare_pcap.c: Ignoring non UDP packet!\n");
continue;
}
udphdr = (struct udphdr *)((char *)ip6hdr + sizeof(*ip6hdr));
} else {
//ipv4
if (iphdr->protocol != IPPROTO_UDP) {
fprintf(stderr, "prepare_pcap.c: Ignoring non UDP packet!\n");
continue;
}
#if defined(__DARWIN) || defined(__CYGWIN) || defined(__FreeBSD__)
udphdr = (struct udphdr *)((char *)iphdr + (iphdr->ihl << 2) + 4);
pktlen = (u_long)(ntohs(udphdr->uh_ulen));
#elif defined ( __HPUX)
udphdr = (struct udphdr *)((char *)iphdr + (iphdr->ihl << 2));
pktlen = (u_long) pkthdr->len - sizeof(*ethhdr) - sizeof(*iphdr);
#else
udphdr = (struct udphdr *)((char *)iphdr + (iphdr->ihl << 2));
pktlen = (u_long)(ntohs(udphdr->len));
#endif
}
if (pktlen > PCAP_MAXPACKET) {
ERROR("Packet size is too big! Recompile with bigger PCAP_MAXPACKET in prepare_pcap.h");
}
pkts->pkts = (pcap_pkt *) realloc(pkts->pkts, sizeof(*(pkts->pkts)) * (n_pkts + 1));
if (!pkts->pkts)
ERROR("Can't re-allocate memory for pcap pkt");
pkt_index = pkts->pkts + n_pkts;
pkt_index->pktlen = pktlen;
pkt_index->ts = pkthdr->ts;
pkt_index->data = (unsigned char *) malloc(pktlen);
if (!pkt_index->data)
ERROR("Can't allocate memory for pcap pkt data");
memcpy(pkt_index->data, udphdr, pktlen);
#if defined(__HPUX) || defined(__DARWIN) || (defined __CYGWIN) || defined(__FreeBSD__)
udphdr->uh_sum = 0 ;
#else
udphdr->check = 0;
#endif
// compute a partial udp checksum
// not including port that will be changed
// when sending RTP
#if defined(__HPUX) || defined(__DARWIN) || (defined __CYGWIN) || defined(__FreeBSD__)
pkt_index->partial_check = check((u_int16_t *) &udphdr->uh_ulen, pktlen - 4) + ntohs(IPPROTO_UDP + pktlen);
#else
pkt_index->partial_check = check((u_int16_t *) &udphdr->len, pktlen - 4) + ntohs(IPPROTO_UDP + pktlen);
#endif
if (max_length < pktlen)
max_length = pktlen;
#if defined(__HPUX) || defined(__DARWIN) || (defined __CYGWIN) || defined(__FreeBSD__)
if (base > ntohs(udphdr->uh_dport))
base = ntohs(udphdr->uh_dport);
#else
if (base > ntohs(udphdr->dest))
base = ntohs(udphdr->dest);
#endif
n_pkts++;
}
pkts->max = pkts->pkts + n_pkts;
pkts->max_length = max_length;
pkts->base = base;
fprintf(stderr, "In pcap %s, npkts %d\nmax pkt length %ld\nbase port %d\n", file, n_pkts, max_length, base);
pcap_close(pcap);
return 0;
}
void free_pkts(pcap_pkts *pkts) {
pcap_pkt *pkt_index;
while (pkt_index < pkts->max) {
free(pkt_index->data);
}
free(pkts->pkts);
}