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wireshark/epan/follow.c

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/* follow.c
*
* Copyright 1998 Mike Hall <mlh@io.com>
*
* Wireshark - Network traffic analyzer
* By Gerald Combs <gerald@wireshark.org>
* Copyright 1998 Gerald Combs
*
* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*
*/
#include "config.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <glib.h>
#include <epan/packet.h>
#include <epan/to_str.h>
#include <epan/dissectors/packet-tcp.h>
#include <epan/dissectors/packet-udp.h>
#include "follow.h"
#include <epan/conversation.h>
#include <epan/tap.h>
#define MAX_IPADDR_LEN 16
typedef struct _tcp_frag {
guint32 seq;
guint32 len;
guint32 data_len;
gchar *data;
struct _tcp_frag *next;
} tcp_frag;
WS_DLL_PUBLIC_DEF
FILE* data_out_file = NULL;
gboolean empty_tcp_stream;
gboolean incomplete_tcp_stream;
static guint32 stream_to_follow[MAX_STREAM] = {0};
static gboolean find_addr[MAX_STREAM] = {FALSE};
static gboolean find_index[MAX_STREAM] = {FALSE};
static address tcp_addr[2];
static guint8 ip_address[2][MAX_IPADDR_LEN];
static guint port[2];
static guint bytes_written[2];
static gboolean is_ipv6 = FALSE;
static int check_fragments( int, tcp_stream_chunk *, guint32 );
static void write_packet_data( int, tcp_stream_chunk *, const char * );
void
follow_stats(follow_stats_t* stats)
{
int i;
for (i = 0; i < 2 ; i++) {
memcpy(stats->ip_address[i], ip_address[i], MAX_IPADDR_LEN);
stats->port[i] = port[i];
stats->bytes_written[i] = bytes_written[i];
stats->is_ipv6 = is_ipv6;
}
}
/* This will build a display filter text that will only
pass the packets related to the stream. There is a
chance that two streams could intersect, but not a
very good one */
gchar*
build_follow_conv_filter( packet_info *pi ) {
char* buf;
int len;
conversation_t *conv=NULL;
struct tcp_analysis *tcpd;
struct udp_analysis *udpd;
wmem_list_frame_t* protos;
int proto_id;
const char* proto_name;
gboolean is_tcp = FALSE, is_udp = FALSE;
protos = wmem_list_head(pi->layers);
/* walk the list of a available protocols in the packet to
figure out if any of them affect context sensitivity */
while (protos != NULL)
{
proto_id = GPOINTER_TO_INT(wmem_list_frame_data(protos));
proto_name = proto_get_protocol_filter_name(proto_id);
if (!strcmp(proto_name, "tcp")) {
is_tcp = TRUE;
} else if (!strcmp(proto_name, "udp")) {
is_udp = TRUE;
}
protos = wmem_list_frame_next(protos);
}
if( ((pi->net_src.type == AT_IPv4 && pi->net_dst.type == AT_IPv4) ||
(pi->net_src.type == AT_IPv6 && pi->net_dst.type == AT_IPv6))
&& is_tcp && (conv=find_conversation(pi->fd->num, &pi->src, &pi->dst, pi->ptype,
pi->srcport, pi->destport, 0)) != NULL ) {
/* TCP over IPv4/6 */
tcpd=get_tcp_conversation_data(conv, pi);
if (tcpd) {
buf = g_strdup_printf("tcp.stream eq %d", tcpd->stream);
stream_to_follow[TCP_STREAM] = tcpd->stream;
if (pi->net_src.type == AT_IPv4) {
len = 4;
is_ipv6 = FALSE;
} else {
len = 16;
is_ipv6 = TRUE;
}
} else {
return NULL;
}
}
else if( ((pi->net_src.type == AT_IPv4 && pi->net_dst.type == AT_IPv4) ||
(pi->net_src.type == AT_IPv6 && pi->net_dst.type == AT_IPv6))
&& is_udp && (conv=find_conversation(pi->fd->num, &pi->src, &pi->dst, pi->ptype,
pi->srcport, pi->destport, 0)) != NULL ) {
/* UDP over IPv4/6 */
udpd=get_udp_conversation_data(conv, pi);
if (udpd) {
buf = g_strdup_printf("udp.stream eq %d", udpd->stream);
stream_to_follow[UDP_STREAM] = udpd->stream;
if (pi->net_src.type == AT_IPv4) {
len = 4;
is_ipv6 = FALSE;
} else {
len = 16;
is_ipv6 = TRUE;
}
} else {
return NULL;
}
}
else {
return NULL;
}
memcpy(ip_address[0], pi->net_src.data, len);
memcpy(ip_address[1], pi->net_dst.data, len);
port[0] = pi->srcport;
port[1] = pi->destport;
return buf;
}
static gboolean
udp_follow_packet(void *tapdata _U_, packet_info *pinfo,
epan_dissect_t *edt _U_, const void *data _U_)
{
if (find_addr[UDP_STREAM]) {
if (pinfo->net_src.type == AT_IPv6) {
is_ipv6 = TRUE;
} else {
is_ipv6 = FALSE;
}
memcpy(ip_address[0], pinfo->net_src.data, pinfo->net_src.len);
memcpy(ip_address[1], pinfo->net_dst.data, pinfo->net_dst.len);
port[0] = pinfo->srcport;
port[1] = pinfo->destport;
find_addr[UDP_STREAM] = FALSE;
}
return FALSE;
}
void
reset_udp_follow(void) {
remove_tap_listener(&stream_to_follow[UDP_STREAM]);
find_addr[UDP_STREAM] = FALSE;
find_index[UDP_STREAM] = FALSE;
}
gchar*
build_follow_index_filter(stream_type stream) {
gchar *buf;
find_addr[stream] = TRUE;
if (stream == TCP_STREAM) {
buf = g_strdup_printf("tcp.stream eq %d", stream_to_follow[TCP_STREAM]);
} else {
GString * error_string;
buf = g_strdup_printf("udp.stream eq %d", stream_to_follow[UDP_STREAM]);
error_string = register_tap_listener("udp_follow", &stream_to_follow[UDP_STREAM], buf, 0, NULL, udp_follow_packet, NULL);
if (error_string) {
g_string_free(error_string, TRUE);
}
}
return buf;
}
/* select a tcp stream to follow via it's address/port pairs */
gboolean
follow_addr(stream_type stream, const address *addr0, guint port0,
const address *addr1, guint port1)
{
if (addr0 == NULL || addr1 == NULL || addr0->type != addr1->type ||
port0 > G_MAXUINT16 || port1 > G_MAXUINT16 ) {
return FALSE;
}
if (find_index[stream] || find_addr[stream]) {
return FALSE;
}
switch (addr0->type) {
default:
return FALSE;
case AT_IPv4:
case AT_IPv6:
is_ipv6 = addr0->type == AT_IPv6;
break;
}
memcpy(ip_address[0], addr0->data, addr0->len);
port[0] = port0;
memcpy(ip_address[1], addr1->data, addr1->len);
port[1] = port1;
if (stream == TCP_STREAM) {
find_index[TCP_STREAM] = TRUE;
SET_ADDRESS(&tcp_addr[0], addr0->type, addr0->len, ip_address[0]);
SET_ADDRESS(&tcp_addr[1], addr1->type, addr1->len, ip_address[1]);
}
return TRUE;
}
/* select a stream to follow via its index */
gboolean
follow_index(stream_type stream, guint32 indx)
{
if (find_index[stream] || find_addr[stream]) {
return FALSE;
}
find_addr[stream] = TRUE;
stream_to_follow[stream] = indx;
memset(ip_address, 0, sizeof ip_address);
port[0] = port[1] = 0;
return TRUE;
}
guint32
get_follow_index(stream_type stream) {
return stream_to_follow[stream];
}
/* here we are going to try and reconstruct the data portion of a TCP
session. We will try and handle duplicates, TCP fragments, and out
of order packets in a smart way. */
static tcp_frag *frags[2] = { 0, 0 };
static guint32 seq[2];
static guint8 src_addr[2][MAX_IPADDR_LEN];
static guint src_port[2] = { 0, 0 };
void
reassemble_tcp( guint32 tcp_stream, guint32 sequence, guint32 acknowledgement,
guint32 length, const char* data, guint32 data_length,
int synflag, address *net_src, address *net_dst,
guint srcport, guint dstport, guint32 packet_num) {
guint8 srcx[MAX_IPADDR_LEN], dstx[MAX_IPADDR_LEN];
int src_index, j, first = 0, len;
guint32 newseq;
tcp_frag *tmp_frag;
tcp_stream_chunk sc;
src_index = -1;
/* First, check if this packet should be processed. */
if (find_index[TCP_STREAM]) {
if ((port[0] == srcport && port[1] == dstport &&
ADDRESSES_EQUAL(&tcp_addr[0], net_src) &&
ADDRESSES_EQUAL(&tcp_addr[1], net_dst))
||
(port[1] == srcport && port[0] == dstport &&
ADDRESSES_EQUAL(&tcp_addr[1], net_src) &&
ADDRESSES_EQUAL(&tcp_addr[0], net_dst))) {
find_index[TCP_STREAM] = FALSE;
stream_to_follow[TCP_STREAM] = tcp_stream;
}
else {
return;
}
}
else if ( tcp_stream != stream_to_follow[TCP_STREAM] )
return;
if ((net_src->type != AT_IPv4 && net_src->type != AT_IPv6) ||
(net_dst->type != AT_IPv4 && net_dst->type != AT_IPv6))
return;
if (net_src->type == AT_IPv4)
len = 4;
else
len = 16;
memcpy(srcx, net_src->data, len);
memcpy(dstx, net_dst->data, len);
/* follow_tcp_index() needs to learn address/port pairs */
if (find_addr[TCP_STREAM]) {
find_addr[TCP_STREAM] = FALSE;
memcpy(ip_address[0], net_src->data, net_src->len);
port[0] = srcport;
memcpy(ip_address[1], net_dst->data, net_dst->len);
port[1] = dstport;
if (net_src->type == AT_IPv6 && net_dst->type == AT_IPv6) {
is_ipv6 = TRUE;
} else {
is_ipv6 = FALSE;
}
}
/* Check to see if we have seen this source IP and port before.
(Yes, we have to check both source IP and port; the connection
might be between two different ports on the same machine.) */
for( j=0; j<2; j++ ) {
if (memcmp(src_addr[j], srcx, len) == 0 && src_port[j] == srcport ) {
src_index = j;
}
}
/* we didn't find it if src_index == -1 */
if( src_index < 0 ) {
/* assign it to a src_index and get going */
for( j=0; j<2; j++ ) {
if( src_port[j] == 0 ) {
memcpy(src_addr[j], srcx, len);
src_port[j] = srcport;
src_index = j;
first = 1;
break;
}
}
}
if( src_index < 0 ) {
fprintf( stderr, "ERROR in reassemble_tcp: Too many addresses!\n");
return;
}
if( data_length < length ) {
incomplete_tcp_stream = TRUE;
}
/* Before adding data for this flow to the data_out_file, check whether
* this frame acks fragments that were already seen. This happens when
* frames are not in the capture file, but were actually seen by the
* receiving host (Fixes bug 592).
*/
if( frags[1-src_index] ) {
memcpy(sc.src_addr, dstx, len);
sc.src_port = dstport;
sc.dlen = 0; /* Will be filled in in check_fragments */
while ( check_fragments( 1-src_index, &sc, acknowledgement ) )
;
}
/* Initialize our stream chunk. This data gets written to disk. */
memcpy(sc.src_addr, srcx, len);
sc.src_port = srcport;
sc.dlen = data_length;
sc.packet_num = packet_num;
/* now that we have filed away the srcs, lets get the sequence number stuff
figured out */
if( first ) {
/* this is the first time we have seen this src's sequence number */
seq[src_index] = sequence + length;
if( synflag ) {
seq[src_index]++;
}
/* write out the packet data */
write_packet_data( src_index, &sc, data );
return;
}
/* if we are here, we have already seen this src, let's
try and figure out if this packet is in the right place */
if( LT_SEQ(sequence, seq[src_index]) ) {
/* this sequence number seems dated, but
check the end to make sure it has no more
info than we have already seen */
newseq = sequence + length;
if( GT_SEQ(newseq, seq[src_index]) ) {
guint32 new_len;
/* this one has more than we have seen. let's get the
payload that we have not seen. */
new_len = seq[src_index] - sequence;
if ( data_length <= new_len ) {
data = NULL;
data_length = 0;
incomplete_tcp_stream = TRUE;
} else {
data += new_len;
data_length -= new_len;
}
sc.dlen = data_length;
sequence = seq[src_index];
length = newseq - seq[src_index];
/* this will now appear to be right on time :) */
}
}
if ( EQ_SEQ(sequence, seq[src_index]) ) {
/* right on time */
seq[src_index] += length;
if( synflag ) seq[src_index]++;
if( data ) {
write_packet_data( src_index, &sc, data );
}
/* done with the packet, see if it caused a fragment to fit */
while( check_fragments( src_index, &sc, 0 ) )
;
}
else {
/* out of order packet */
if(data_length > 0 && GT_SEQ(sequence, seq[src_index]) ) {
tmp_frag = (tcp_frag *)g_malloc( sizeof( tcp_frag ) );
tmp_frag->data = (gchar *)g_malloc( data_length );
tmp_frag->seq = sequence;
tmp_frag->len = length;
tmp_frag->data_len = data_length;
memcpy( tmp_frag->data, data, data_length );
if( frags[src_index] ) {
tmp_frag->next = frags[src_index];
} else {
tmp_frag->next = NULL;
}
frags[src_index] = tmp_frag;
}
}
} /* end reassemble_tcp */
/* here we search through all the frag we have collected to see if
one fits */
static int
check_fragments( int idx, tcp_stream_chunk *sc, guint32 acknowledged ) {
tcp_frag *prev = NULL;
tcp_frag *current;
guint32 lowest_seq;
gchar *dummy_str;
current = frags[idx];
if( current ) {
lowest_seq = current->seq;
while( current ) {
if( GT_SEQ(lowest_seq, current->seq) ) {
lowest_seq = current->seq;
}
if( LT_SEQ(current->seq, seq[idx]) ) {
guint32 newseq;
/* this sequence number seems dated, but
check the end to make sure it has no more
info than we have already seen */
newseq = current->seq + current->len;
if( GT_SEQ(newseq, seq[idx]) ) {
guint32 new_pos;
/* this one has more than we have seen. let's get the
payload that we have not seen. This happens when
part of this frame has been retransmitted */
new_pos = seq[idx] - current->seq;
if ( current->data_len > new_pos ) {
sc->dlen = current->data_len - new_pos;
write_packet_data( idx, sc, current->data + new_pos );
}
seq[idx] += (current->len - new_pos);
}
/* Remove the fragment from the list as the "new" part of it
* has been processed or its data has been seen already in
* another packet. */
if( prev ) {
prev->next = current->next;
} else {
frags[idx] = current->next;
}
g_free( current->data );
g_free( current );
return 1;
}
if( EQ_SEQ(current->seq, seq[idx]) ) {
/* this fragment fits the stream */
if( current->data ) {
sc->dlen = current->data_len;
write_packet_data( idx, sc, current->data );
}
seq[idx] += current->len;
if( prev ) {
prev->next = current->next;
} else {
frags[idx] = current->next;
}
g_free( current->data );
g_free( current );
return 1;
}
prev = current;
current = current->next;
}
if( GT_SEQ(acknowledged, lowest_seq) ) {
/* There are frames missing in the capture file that were seen
* by the receiving host. Add dummy stream chunk with the data
* "[xxx bytes missing in capture file]".
*/
dummy_str = g_strdup_printf("[%d bytes missing in capture file]",
(int)(lowest_seq - seq[idx]) );
sc->dlen = (guint32) strlen(dummy_str);
write_packet_data( idx, sc, dummy_str );
g_free(dummy_str);
seq[idx] = lowest_seq;
return 1;
}
}
return 0;
}
/* this should always be called before we start to reassemble a stream */
void
reset_tcp_reassembly(void)
{
tcp_frag *current, *next;
int i;
empty_tcp_stream = TRUE;
incomplete_tcp_stream = FALSE;
find_addr[TCP_STREAM] = FALSE;
find_index[TCP_STREAM] = FALSE;
for( i=0; i<2; i++ ) {
seq[i] = 0;
memset(src_addr[i], '\0', MAX_IPADDR_LEN);
src_port[i] = 0;
memset(ip_address[i], '\0', MAX_IPADDR_LEN);
port[i] = 0;
bytes_written[i] = 0;
current = frags[i];
while( current ) {
next = current->next;
g_free( current->data );
g_free( current );
current = next;
}
frags[i] = NULL;
}
}
static void
write_packet_data( int idx, tcp_stream_chunk *sc, const char *data )
{
size_t ret;
ret = fwrite( sc, 1, sizeof(tcp_stream_chunk), data_out_file );
DISSECTOR_ASSERT(sizeof(tcp_stream_chunk) == ret);
ret = fwrite( data, 1, sc->dlen, data_out_file );
DISSECTOR_ASSERT(sc->dlen == ret);
bytes_written[idx] += sc->dlen;
empty_tcp_stream = FALSE;
}
/*
* Editor modelines - http://www.wireshark.org/tools/modelines.html
*
* Local Variables:
* c-basic-offset: 2
* tab-width: 8
* indent-tabs-mode: nil
* End:
*
* ex: set shiftwidth=2 tabstop=8 expandtab:
* :indentSize=2:tabSize=8:noTabs=true:
*/
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