3 * $Id: follow.c,v 1.31 2002/08/28 21:00:06 jmayer Exp $
5 * Copyright 1998 Mike Hall <mlh@io.com>
7 * Ethereal - Network traffic analyzer
8 * By Gerald Combs <gerald@ethereal.com>
9 * Copyright 1998 Gerald Combs
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License
13 * as published by the Free Software Foundation; either version 2
14 * of the License, or (at your option) any later version.
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
39 #include <epan/packet.h>
42 FILE* data_out_file = NULL;
44 gboolean incomplete_tcp_stream = FALSE;
46 static guint8 ip_address[2][MAX_IPADDR_LEN];
47 static guint tcp_port[2];
48 static guint bytes_written[2];
49 static gboolean is_ipv6 = FALSE;
51 static int check_fragments( int, tcp_stream_chunk * );
52 static void write_packet_data( int, tcp_stream_chunk *, const char * );
55 follow_tcp_stats(follow_tcp_stats_t* stats)
59 for (i = 0; i < 2 ; i++) {
60 memcpy(stats->ip_address[i], ip_address[i], MAX_IPADDR_LEN);
61 stats->tcp_port[i] = tcp_port[i];
62 stats->bytes_written[i] = bytes_written[i];
63 stats->is_ipv6 = is_ipv6;
67 /* this will build libpcap filter text that will only
68 pass the packets related to the stream. There is a
69 chance that two streams could intersect, but not a
72 build_follow_filter( packet_info *pi ) {
73 char* buf = g_malloc(1024);
75 if( pi->net_src.type == AT_IPv4 && pi->net_dst.type == AT_IPv4
76 && pi->ipproto == 6 ) {
79 "(ip.addr eq %s and ip.addr eq %s) and (tcp.port eq %d and tcp.port eq %d)",
80 ip_to_str( pi->net_src.data),
81 ip_to_str( pi->net_dst.data),
82 pi->srcport, pi->destport );
86 else if( pi->net_src.type == AT_IPv6 && pi->net_dst.type == AT_IPv6
87 && pi->ipproto == 6 ) {
90 "(ipv6.addr eq %s and ipv6.addr eq %s) and (tcp.port eq %d and tcp.port eq %d)",
91 ip6_to_str((struct e_in6_addr *)pi->net_src.data),
92 ip6_to_str((struct e_in6_addr *)pi->net_dst.data),
93 pi->srcport, pi->destport );
101 memcpy(ip_address[0], pi->net_src.data, len);
102 memcpy(ip_address[1], pi->net_dst.data, len);
103 tcp_port[0] = pi->srcport;
104 tcp_port[1] = pi->destport;
108 /* here we are going to try and reconstruct the data portion of a TCP
109 session. We will try and handle duplicates, TCP fragments, and out
110 of order packets in a smart way. */
112 static tcp_frag *frags[2] = { 0, 0 };
113 static gulong seq[2];
114 static guint8 src_addr[2][MAX_IPADDR_LEN];
115 static guint src_port[2] = { 0, 0 };
118 reassemble_tcp( gulong sequence, gulong length, const char* data,
119 gulong data_length, int synflag, address *net_src,
120 address *net_dst, guint srcport, guint dstport) {
121 guint8 srcx[MAX_IPADDR_LEN], dstx[MAX_IPADDR_LEN];
122 int src_index, j, first = 0, len;
129 /* First, check if this packet should be processed. */
131 if ((net_src->type != AT_IPv4 && net_src->type != AT_IPv6) ||
132 (net_dst->type != AT_IPv4 && net_dst->type != AT_IPv6))
135 if (net_src->type == AT_IPv4)
140 /* Now check if the packet is for this connection. */
141 memcpy(srcx, net_src->data, len);
142 memcpy(dstx, net_dst->data, len);
143 if ((memcmp(srcx, ip_address[0], len) != 0 &&
144 memcmp(srcx, ip_address[1], len) != 0) ||
145 (memcmp(dstx, ip_address[0], len) != 0 &&
146 memcmp(dstx, ip_address[1], len) != 0) ||
147 (srcport != tcp_port[0] && srcport != tcp_port[1]) ||
148 (dstport != tcp_port[0] && dstport != tcp_port[1]))
151 /* Initialize our stream chunk. This data gets written to disk. */
152 memcpy(sc.src_addr, srcx, len);
153 sc.src_port = srcport;
154 sc.dlen = data_length;
156 /* Check to see if we have seen this source IP and port before.
157 (Yes, we have to check both source IP and port; the connection
158 might be between two different ports on the same machine.) */
159 for( j=0; j<2; j++ ) {
160 if (memcmp(src_addr[j], srcx, len) == 0 && src_port[j] == srcport ) {
164 /* we didn't find it if src_index == -1 */
165 if( src_index < 0 ) {
166 /* assign it to a src_index and get going */
167 for( j=0; j<2; j++ ) {
168 if( src_port[j] == 0 ) {
169 memcpy(src_addr[j], srcx, len);
170 src_port[j] = srcport;
177 if( src_index < 0 ) {
178 fprintf( stderr, "ERROR in reassemble_tcp: Too many addresses!\n");
182 if( data_length < length ) {
183 incomplete_tcp_stream = TRUE;
186 /* now that we have filed away the srcs, lets get the sequence number stuff
189 /* this is the first time we have seen this src's sequence number */
190 seq[src_index] = sequence + length;
194 /* write out the packet data */
195 write_packet_data( src_index, &sc, data );
198 /* if we are here, we have already seen this src, let's
199 try and figure out if this packet is in the right place */
200 if( sequence < seq[src_index] ) {
201 /* this sequence number seems dated, but
202 check the end to make sure it has no more
203 info than we have already seen */
204 newseq = sequence + length;
205 if( newseq > seq[src_index] ) {
208 /* this one has more than we have seen. let's get the
209 payload that we have not seen. */
211 new_len = seq[src_index] - sequence;
213 if ( data_length <= new_len ) {
216 incomplete_tcp_stream = TRUE;
219 data_length -= new_len;
221 sc.dlen = data_length;
222 sequence = seq[src_index];
223 length = newseq - seq[src_index];
225 /* this will now appear to be right on time :) */
228 if ( sequence == seq[src_index] ) {
230 seq[src_index] += length;
231 if( synflag ) seq[src_index]++;
233 write_packet_data( src_index, &sc, data );
235 /* done with the packet, see if it caused a fragment to fit */
236 while( check_fragments( src_index, &sc ) )
240 /* out of order packet */
241 if(data_length > 0 && sequence > seq[src_index] ) {
242 tmp_frag = (tcp_frag *)malloc( sizeof( tcp_frag ) );
243 tmp_frag->data = (guchar *)malloc( data_length );
244 tmp_frag->seq = sequence;
245 tmp_frag->len = length;
246 tmp_frag->data_len = data_length;
247 memcpy( tmp_frag->data, data, data_length );
248 if( frags[src_index] ) {
249 tmp_frag->next = frags[src_index];
251 tmp_frag->next = NULL;
253 frags[src_index] = tmp_frag;
256 } /* end reassemble_tcp */
258 /* here we search through all the frag we have collected to see if
261 check_fragments( int index, tcp_stream_chunk *sc ) {
262 tcp_frag *prev = NULL;
264 current = frags[index];
266 if( current->seq == seq[index] ) {
267 /* this fragment fits the stream */
268 if( current->data ) {
269 sc->dlen = current->data_len;
270 write_packet_data( index, sc, current->data );
272 seq[index] += current->len;
274 prev->next = current->next;
276 frags[index] = current->next;
278 free( current->data );
283 current = current->next;
288 /* this should always be called before we start to reassemble a stream */
290 reset_tcp_reassembly() {
291 tcp_frag *current, *next;
293 incomplete_tcp_stream = FALSE;
294 for( i=0; i<2; i++ ) {
296 memset(src_addr[i], '\0', MAX_IPADDR_LEN);
298 memset(ip_address[i], '\0', MAX_IPADDR_LEN);
300 bytes_written[i] = 0;
303 next = current->next;
304 free( current->data );
313 write_packet_data( int index, tcp_stream_chunk *sc, const char *data )
315 fwrite( sc, 1, sizeof(tcp_stream_chunk), data_out_file );
316 fwrite( data, 1, sc->dlen, data_out_file );
317 bytes_written[index] += sc->dlen;