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wireshark/epan/follow.c
Sake Blok 8f7d4aff96 Fixes the "follow tcp stream" output when there are frames missing in the 
capture file that were actually on the wire. The reassembly code waited for 
the gaps to be filled in by retransmissions, which would never come.

With this fix all acknowledged data will be output with "[xxx bytes missing in 
capture file]" inserted in every gap.


svn path=/trunk/; revision=23878
2007-12-15 23:25:05 +00:00

397 lines
11 KiB
C
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/* follow.c
*
* $Id$
*
* 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#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/ipproto.h>
#include "follow.h"
#define MAX_IPADDR_LEN 16
typedef struct _tcp_frag {
gulong seq;
gulong len;
gulong data_len;
gchar *data;
struct _tcp_frag *next;
} tcp_frag;
FILE* data_out_file = NULL;
gboolean empty_tcp_stream;
gboolean incomplete_tcp_stream;
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 *, gulong );
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 libpcap 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 */
char*
build_follow_filter( packet_info *pi ) {
char* buf;
int len;
if( pi->net_src.type == AT_IPv4 && pi->net_dst.type == AT_IPv4
&& pi->ipproto == IP_PROTO_TCP ) {
/* TCP over IPv4 */
buf = g_strdup_printf(
"(ip.addr eq %s and ip.addr eq %s) and (tcp.port eq %d and tcp.port eq %d)",
ip_to_str( pi->net_src.data),
ip_to_str( pi->net_dst.data),
pi->srcport, pi->destport );
len = 4;
is_ipv6 = FALSE;
}
else if( pi->net_src.type == AT_IPv4 && pi->net_dst.type == AT_IPv4
&& pi->ipproto == IP_PROTO_UDP ) {
/* UDP over IPv4 */
buf = g_strdup_printf(
"(ip.addr eq %s and ip.addr eq %s) and (udp.port eq %d and udp.port eq %d)",
ip_to_str( pi->net_src.data),
ip_to_str( pi->net_dst.data),
pi->srcport, pi->destport );
len = 4;
is_ipv6 = FALSE;
}
else if( pi->net_src.type == AT_IPv6 && pi->net_dst.type == AT_IPv6
&& pi->ipproto == IP_PROTO_TCP ) {
/* TCP over IPv6 */
buf = g_strdup_printf(
"(ipv6.addr eq %s and ipv6.addr eq %s) and (tcp.port eq %d and tcp.port eq %d)",
ip6_to_str((const struct e_in6_addr *)pi->net_src.data),
ip6_to_str((const struct e_in6_addr *)pi->net_dst.data),
pi->srcport, pi->destport );
len = 16;
is_ipv6 = TRUE;
}
else if( pi->net_src.type == AT_IPv6 && pi->net_dst.type == AT_IPv6
&& pi->ipproto == IP_PROTO_UDP ) {
/* UDP over IPv6 */
buf = g_strdup_printf(
"(ipv6.addr eq %s and ipv6.addr eq %s) and (udp.port eq %d and udp.port eq %d)",
ip6_to_str((const struct e_in6_addr *)pi->net_src.data),
ip6_to_str((const struct e_in6_addr *)pi->net_dst.data),
pi->srcport, pi->destport );
len = 16;
is_ipv6 = TRUE;
}
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;
}
/* 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 gulong seq[2];
static guint8 src_addr[2][MAX_IPADDR_LEN];
static guint src_port[2] = { 0, 0 };
void
reassemble_tcp( gulong sequence, gulong acknowledgement, gulong length,
const char* data, gulong data_length, int synflag,
address *net_src, address *net_dst,
guint srcport, guint dstport) {
guint8 srcx[MAX_IPADDR_LEN], dstx[MAX_IPADDR_LEN];
int src_index, j, first = 0, len;
gulong newseq;
tcp_frag *tmp_frag;
tcp_stream_chunk sc;
src_index = -1;
/* First, check if this packet should be processed. */
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;
/* Now check if the packet is for this connection. */
memcpy(srcx, net_src->data, len);
memcpy(dstx, net_dst->data, len);
if (
! (
memcmp(srcx, ip_address[0], len) == 0 &&
memcmp(dstx, ip_address[1], len) == 0 &&
srcport == port[0] &&
dstport == port[1]
) &&
! (
memcmp(srcx, ip_address[1], len) == 0 &&
memcmp(dstx, ip_address[0], len) == 0 &&
srcport == port[1] &&
dstport == port[0]
)
)
return;
/* 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;
/* 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( 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( newseq > seq[src_index] ) {
gulong 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 ( 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 && 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 index, tcp_stream_chunk *sc, gulong acknowledged ) {
tcp_frag *prev = NULL;
tcp_frag *current;
gulong lowest_seq;
gchar *dummy_str;
current = frags[index];
if( current ) {
lowest_seq = current->seq;
while( current ) {
if( current->seq == seq[index] ) {
/* this fragment fits the stream */
if( current->data ) {
sc->dlen = current->data_len;
write_packet_data( index, sc, current->data );
}
seq[index] += current->len;
if( prev ) {
prev->next = current->next;
} else {
frags[index] = current->next;
}
g_free( current->data );
g_free( current );
return 1;
}
prev = current;
current = current->next;
}
if( acknowledged - lowest_seq > 0 ) {
/* 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[index]) );
sc->dlen = strlen(dummy_str);
write_packet_data( index, sc, dummy_str );
g_free(dummy_str);
seq[index] = 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;
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 index, tcp_stream_chunk *sc, const char *data )
{
DISSECTOR_ASSERT(1 * sizeof(tcp_stream_chunk) == fwrite( sc, 1, sizeof(tcp_stream_chunk), data_out_file ));
DISSECTOR_ASSERT(1 * sc->dlen == fwrite( data, 1, sc->dlen, data_out_file ));
bytes_written[index] += sc->dlen;
empty_tcp_stream = FALSE;
}
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