3 * $Id: follow.c,v 1.4 1998/10/28 01:29:16 guy Exp $
5 * Copyright 1998 Mike Hall <mlh@io.com>
7 * Ethereal - Network traffic analyzer
8 * By Gerald Combs <gerald@zing.org>
9 * Copyright 1998 Gerald Combs
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation; either version 2
15 * of the License, or (at your option) any later version.
17 * This program is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU General Public License for more details.
22 * You should have received a copy of the GNU General Public License
23 * along with this program; if not, write to the Free Software
24 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
36 #ifdef HAVE_SYS_TYPES_H
37 # include <sys/types.h>
44 extern FILE* data_out_file;
46 /* this will build libpcap filter text that will only
47 pass the packets related to the stream. There is a
48 chance that two streams could intersect, but not a
51 build_follow_filter( packet_info *pi ) {
52 char* buf = malloc(1024);
53 if( pi->ipproto == 6 ) {
55 sprintf( buf, "host %s and host %s and (ip proto \\tcp) and (port %d and port %d)",
56 pi->srcip, pi->destip, pi->srcport, pi->destport );
65 /* here we are going to try and reconstruct the data portion of a TCP
66 session. We will try and handle duplicates, TCP fragments, and out
67 of order packets in a smart way. */
69 static tcp_frag *frags[2] = { 0, 0};
71 static u_long src[2] = { 0, 0 };
74 reassemble_tcp( u_long sequence, u_long length, const char* data, int synflag, u_long srcx ) {
75 int src_index, j, first = 0;
79 /* first we check to see if we have seen this src ip before. */
80 for( j=0; j<2; j++ ) {
81 if( src[j] == srcx ) {
85 /* we didn't find it if src_index == -1 */
87 /* assign it to a src_index and get going */
88 for( j=0; j<2; j++ ) {
98 fprintf( stderr, "ERROR in reassemble_tcp: Too many addresses!\n");
101 /* now that we have filed away the srcs, lets get the sequence number stuff
104 /* this is the first time we have seen this src's sequence number */
105 seq[src_index] = sequence + length;
109 /* write out the packet data */
110 write_packet_data( data, length );
113 /* if we are here, we have already seen this src, let's
114 try and figure out if this packet is in the right place */
115 if( sequence < seq[src_index] ) {
116 /* this sequence number seems dated, but
117 check the end to make sure it has no more
118 info than we have already seen */
119 newseq = sequence + length;
120 if( newseq > seq[src_index] ) {
121 /* this one has more than we have seen. let's get the
122 payload that we have not seen. */
123 data += ( seq[src_index] - sequence );
124 sequence = seq[src_index];
125 length = newseq - seq[src_index];
126 /* this will now appear to be right on time :) */
129 if ( sequence == seq[src_index] ) {
131 seq[src_index] += length;
132 if( synflag ) seq[src_index]++;
133 write_packet_data( data, length );
134 /* done with the packet, see if it caused a fragment to fit */
135 while( check_fragments( src_index ) )
139 /* out of order packet */
140 if( sequence > seq[src_index] ) {
141 tmp_frag = (tcp_frag *)malloc( sizeof( tcp_frag ) );
142 tmp_frag->data = (u_char *)malloc( length );
143 tmp_frag->seq = sequence;
144 tmp_frag->len = length;
145 memcpy( tmp_frag->data, data, length );
146 if( frags[src_index] ) {
147 tmp_frag->next = frags[src_index];
149 tmp_frag->next = NULL;
151 frags[src_index] = tmp_frag;
154 } /* end reassemble_tcp */
156 /* here we search through all the frag we have collected to see if
159 check_fragments( int index ) {
160 tcp_frag *prev = NULL;
162 current = frags[index];
164 if( current->seq == seq[index] ) {
165 /* this fragment fits the stream */
166 write_packet_data( current->data, current->len );
167 seq[index] += current->len;
169 prev->next = current->next;
171 src[index] = current->next;
173 free( current->data );
178 current = current->next;
183 /* this should always be called before we start to reassemble a stream */
185 reset_tcp_reassembly() {
186 tcp_frag *current, *next;
188 for( i=0; i<2; i++ ) {
193 next = current->next;
194 free( current->data );
203 write_packet_data( const u_char* data, int length ) {
204 fwrite( data, 1, length, data_out_file );