2 * Routines for TCP packet disassembly
4 * $Id: packet-tcp.c,v 1.121 2001/12/05 08:20:30 guy Exp $
6 * Ethereal - Network traffic analyzer
7 * By Gerald Combs <gerald@ethereal.com>
8 * Copyright 1998 Gerald Combs
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version 2
13 * of the License, or (at your option) any later version.
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
29 #ifdef HAVE_SYS_TYPES_H
30 # include <sys/types.h>
33 #ifdef HAVE_NETINET_IN_H
34 # include <netinet/in.h>
42 #ifdef NEED_SNPRINTF_H
43 # include "snprintf.h"
50 #include "packet-tcp.h"
51 #include "packet-ip.h"
52 #include "conversation.h"
54 #include "reassemble.h"
56 /* Place TCP summary in proto tree */
57 static gboolean tcp_summary_in_tree = TRUE;
59 extern FILE* data_out_file;
61 static int proto_tcp = -1;
62 static int hf_tcp_srcport = -1;
63 static int hf_tcp_dstport = -1;
64 static int hf_tcp_port = -1;
65 static int hf_tcp_seq = -1;
66 static int hf_tcp_nxtseq = -1;
67 static int hf_tcp_ack = -1;
68 static int hf_tcp_hdr_len = -1;
69 static int hf_tcp_flags = -1;
70 static int hf_tcp_flags_cwr = -1;
71 static int hf_tcp_flags_ecn = -1;
72 static int hf_tcp_flags_urg = -1;
73 static int hf_tcp_flags_ack = -1;
74 static int hf_tcp_flags_push = -1;
75 static int hf_tcp_flags_reset = -1;
76 static int hf_tcp_flags_syn = -1;
77 static int hf_tcp_flags_fin = -1;
78 static int hf_tcp_window_size = -1;
79 static int hf_tcp_checksum = -1;
80 static int hf_tcp_checksum_bad = -1;
81 static int hf_tcp_urgent_pointer = -1;
83 static gint ett_tcp = -1;
84 static gint ett_tcp_flags = -1;
85 static gint ett_tcp_options = -1;
86 static gint ett_tcp_option_sack = -1;
87 static gint ett_tcp_segments = -1;
89 static dissector_table_t subdissector_table;
90 static heur_dissector_list_t heur_subdissector_list;
91 static dissector_handle_t data_handle;
93 /* TCP structs and definitions */
104 /* Minimum TCP header length. */
105 #define TCPH_MIN_LEN 20
111 #define TCPOPT_NOP 1 /* Padding */
112 #define TCPOPT_EOL 0 /* End of options */
113 #define TCPOPT_MSS 2 /* Segment size negotiating */
114 #define TCPOPT_WINDOW 3 /* Window scaling */
115 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */
116 #define TCPOPT_SACK 5 /* SACK Block */
117 #define TCPOPT_ECHO 6
118 #define TCPOPT_ECHOREPLY 7
119 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
121 #define TCPOPT_CCNEW 12
122 #define TCPOPT_CCECHO 13
123 #define TCPOPT_MD5 19 /* RFC2385 */
129 #define TCPOLEN_MSS 4
130 #define TCPOLEN_WINDOW 3
131 #define TCPOLEN_SACK_PERM 2
132 #define TCPOLEN_SACK_MIN 2
133 #define TCPOLEN_ECHO 6
134 #define TCPOLEN_ECHOREPLY 6
135 #define TCPOLEN_TIMESTAMP 10
137 #define TCPOLEN_CCNEW 6
138 #define TCPOLEN_CCECHO 6
139 #define TCPOLEN_MD5 18
143 /* Desegmentation of TCP streams */
144 /* table to hold defragmented TCP streams */
145 static GHashTable *tcp_fragment_table = NULL;
147 tcp_fragment_init(void)
149 fragment_table_init(&tcp_fragment_table);
152 /* functions to trace tcp segments */
153 /* Enable desegmenting of TCP streams */
154 static gboolean tcp_desegment = FALSE;
156 static GHashTable *tcp_segment_table = NULL;
157 static GMemChunk *tcp_segment_key_chunk = NULL;
158 static int tcp_segment_init_count = 200;
159 static GMemChunk *tcp_segment_address_chunk = NULL;
160 static int tcp_segment_address_init_count = 500;
162 typedef struct _tcp_segment_key {
163 /* for ouwn bookkeeping inside packet-tcp.c */
174 free_all_segments(gpointer key_arg, gpointer value, gpointer user_data)
176 tcp_segment_key *key = key_arg;
178 if((key->src)&&(key->src->data)){
179 g_free((gpointer)key->src->data);
183 if((key->dst)&&(key->dst->data)){
184 g_free((gpointer)key->dst->data);
192 tcp_segment_hash(gconstpointer k)
194 tcp_segment_key *key = (tcp_segment_key *)k;
200 tcp_segment_equal(gconstpointer k1, gconstpointer k2)
202 tcp_segment_key *key1 = (tcp_segment_key *)k1;
203 tcp_segment_key *key2 = (tcp_segment_key *)k2;
205 return ( ( (key1->seq==key2->seq)
206 &&(ADDRESSES_EQUAL(key1->src, key2->src))
207 &&(ADDRESSES_EQUAL(key1->dst, key2->dst))
212 tcp_desegment_init(void)
215 /* dont allocate any memory chunks unless the user really
222 if(tcp_segment_table){
223 g_hash_table_foreach_remove(tcp_segment_table,
224 free_all_segments, NULL);
226 tcp_segment_table = g_hash_table_new(tcp_segment_hash,
230 if(tcp_segment_key_chunk){
231 g_mem_chunk_destroy(tcp_segment_key_chunk);
233 tcp_segment_key_chunk = g_mem_chunk_new("tcp_segment_key_chunk",
234 sizeof(tcp_segment_key),
235 tcp_segment_init_count*sizeof(tcp_segment_key),
238 if(tcp_segment_address_chunk){
239 g_mem_chunk_destroy(tcp_segment_address_chunk);
241 tcp_segment_address_chunk = g_mem_chunk_new("tcp_segment_address_chunk",
243 tcp_segment_address_init_count*sizeof(address),
248 desegment_tcp(tvbuff_t *tvb, packet_info *pinfo, int offset,
249 guint32 seq, guint32 nxtseq,
250 guint32 sport, guint32 dport,
251 proto_tree *tree, proto_tree *tcp_tree)
253 struct tcpinfo *tcpinfo = pinfo->private_data;
254 fragment_data *ipfd_head;
255 tcp_segment_key old_tsk, *tsk;
256 gboolean must_desegment = FALSE;
257 gboolean called_dissector = FALSE;
262 * Initialize these to assume no desegmentation.
263 * If that's not the case, these will be set appropriately
264 * by the subdissector.
266 pinfo->desegment_offset = 0;
267 pinfo->desegment_len = 0;
270 * Initialize this to assume that this segment will just be
271 * added to the middle of a desegmented chunk of data, so
272 * that we should show it all as data.
273 * If that's not the case, it will be set appropriately.
275 deseg_offset = offset;
277 /* First we must check if this TCP segment should be desegmented.
278 This is only to check if we should desegment this packet,
279 so we dont spend time doing COPY_ADDRESS/g_free.
280 We just "borrow" some address structures from pinfo instead. Cheaper.
282 old_tsk.src = &pinfo->src;
283 old_tsk.dst = &pinfo->dst;
285 tsk = g_hash_table_lookup(tcp_segment_table, &old_tsk);
288 /* OK, this segment was found, which means it continues
289 a higher-level PDU. This means we must desegment it.
290 Add it to the defragmentation lists.
292 ipfd_head = fragment_add(tvb, offset, pinfo, tsk->start_seq,
294 seq - tsk->start_seq,
296 (nxtseq < (tsk->start_seq + tsk->tot_len)) );
299 /* fragment_add() returned NULL, This means that
300 desegmentation is not completed yet.
301 (its like defragmentation but we know we will
302 always add the segments in order).
303 XXX - no, we don't; there is no guarantee that
304 TCP segments are in order on the wire.
306 we must add next segment to our table so we will
309 tcp_segment_key *new_tsk;
311 new_tsk = g_mem_chunk_alloc(tcp_segment_key_chunk);
312 memcpy(new_tsk, tsk, sizeof(tcp_segment_key));
314 g_hash_table_insert(tcp_segment_table,new_tsk,new_tsk);
317 /* This segment was not found in our table, so it doesn't
318 contain a continuation of a higher-level PDU.
319 Call the normal subdissector.
321 decode_tcp_ports(tvb, offset, pinfo, tree,
323 called_dissector = TRUE;
325 /* Did the subdissector ask us to desegment some more data
326 before it could handle the packet?
327 If so we have to create some structures in our table but
328 this is something we only do the first time we see this
331 if(pinfo->desegment_len) {
332 if (!pinfo->fd->flags.visited)
333 must_desegment = TRUE;
336 * Set "deseg_offset" to the offset in "tvb"
337 * of the first byte of data that the
338 * subdissector didn't process.
340 deseg_offset = offset + pinfo->desegment_offset;
343 /* Either no desegmentation is necessary, or this is
344 segment contains the beginning but not the end of
345 a higher-level PDU and thus isn't completely
351 /* is it completely desegmented? */
354 proto_tree *st = NULL;
355 proto_item *si = NULL;
357 /* first we show a tree with all segments */
358 si = proto_tree_add_text(tcp_tree, tvb, 0, 0,
360 st = proto_item_add_subtree(si, ett_tcp_segments);
361 for(ipfd=ipfd_head->next; ipfd; ipfd=ipfd->next){
362 proto_tree_add_text(st, tvb, 0, 0,
363 "Frame:%d seq#:%d-%d [%d-%d]",
365 tsk->start_seq + ipfd->offset,
366 tsk->start_seq + ipfd->offset + ipfd->len - 1,
368 ipfd->offset + ipfd->len - 1);
372 * We only call subdissector for the last segment.
373 * Note that the last segment may include more than what
376 if(nxtseq >= (tsk->start_seq + tsk->tot_len)){
377 /* ok, lest call subdissector with desegmented data */
380 /* create a new TVB structure for desegmented data */
381 next_tvb = tvb_new_real_data(ipfd_head->data,
382 ipfd_head->datalen, ipfd_head->datalen,
385 /* add this tvb as a child to the original one */
386 tvb_set_child_real_data_tvbuff(tvb, next_tvb);
388 /* add desegmented data to the data source list */
389 pinfo->fd->data_src = g_slist_append(pinfo->fd->data_src, next_tvb);
391 /* indicate that this is reassembled data */
392 tcpinfo->is_reassembled = TRUE;
394 /* call subdissector */
395 decode_tcp_ports(next_tvb, 0, pinfo, tree,
397 called_dissector = TRUE;
399 /* Did the subdissector ask us to desegment some more
400 data? This means that the data at the beginning
401 of this segment completed a higher-level PDU,
402 but the data at the end of this segment started
403 a higher-level PDU but didn't complete it.
405 If so we have to create some structures in our
406 table but this is something we only do the first
407 time we see this packet.
409 if(pinfo->desegment_len) {
410 if (!pinfo->fd->flags.visited)
411 must_desegment = TRUE;
414 * The stuff we couldn't dissect must have
415 * come from this segment, so it's all in
418 * "pinfo->desegment_offset" is relative
419 * to the beginning of "next_tvb";
420 * we want an offset relative to the
421 * beginning of "tvb".
423 * First, compute the offset relative to
424 * the *end* of "next_tvb" - i.e., the number
425 * of bytes before the end of "next_tvb"
426 * at which the subdissector stopped.
427 * That's the length of "next_tvb" minus
428 * the offset, relative to the beginning
429 * of "next_tvb, at which the subdissector
433 ipfd_head->datalen - pinfo->desegment_offset;
436 * "tvb" and "next_tvb" end at the same byte
437 * of data, so the offset relative to the
438 * end of "next_tvb" of the byte at which
439 * we stopped is also the offset relative
440 * to the end of "tvb" of the byte at which
443 * Convert that back into an offset relative
444 * to the beginninng of "tvb", by taking
445 * the length of "tvb" and subtracting the
446 * offset relative to the end.
448 deseg_offset = tvb_length(tvb) - deseg_offset;
453 if (must_desegment) {
454 tcp_segment_key *tsk, *new_tsk;
457 * The sequence number at which the stuff to be desegmented
458 * starts is the sequence number of the byte at an offset
459 * of "deseg_offset" into "tvb".
461 * The sequence number of the byte at an offset of "offset"
462 * is "seq", i.e. the starting sequence number of this
463 * segment, so the sequence number of the byte at
464 * "deseg_offset" is "seq + (deseg_offset - offset)".
466 deseg_seq = seq + (deseg_offset - offset);
469 * XXX - how do we detect out-of-order transmissions?
470 * We can't just check for "nxtseq" being greater than
471 * "tsk->start_seq"; for now, we check for the difference
472 * being less than a megabyte, but this is a really
473 * gross hack - we really need to handle out-of-order
474 * transmissions correctly.
476 if ((nxtseq - deseg_seq) <= 1024*1024) {
477 /* OK, subdissector wants us to desegment
478 some data before it can process it. Add
479 what remains of this packet and set
480 up next packet/sequence number as well.
482 We must remember this segment
484 tsk = g_mem_chunk_alloc(tcp_segment_key_chunk);
485 tsk->src = g_mem_chunk_alloc(tcp_segment_address_chunk);
486 COPY_ADDRESS(tsk->src, &pinfo->src);
487 tsk->dst = g_mem_chunk_alloc(tcp_segment_address_chunk);
488 COPY_ADDRESS(tsk->dst, &pinfo->dst);
489 tsk->seq = deseg_seq;
490 tsk->start_seq = tsk->seq;
491 tsk->tot_len = nxtseq - tsk->start_seq + pinfo->desegment_len;
492 tsk->first_frame = pinfo->fd->num;
493 g_hash_table_insert(tcp_segment_table, tsk, tsk);
495 /* Add portion of segment unprocessed by the subdissector
496 to defragmentation lists */
497 fragment_add(tvb, deseg_offset, pinfo, tsk->start_seq,
499 tsk->seq - tsk->start_seq,
500 nxtseq - tsk->start_seq,
501 (nxtseq < tsk->start_seq + tsk->tot_len));
503 /* this is the next segment in the sequence we want */
504 new_tsk = g_mem_chunk_alloc(tcp_segment_key_chunk);
505 memcpy(new_tsk, tsk, sizeof(tcp_segment_key));
506 new_tsk->seq = nxtseq;
507 g_hash_table_insert(tcp_segment_table,new_tsk,new_tsk);
511 if (!called_dissector || pinfo->desegment_len != 0) {
513 * Either we didn't call the subdissector at all (i.e.,
514 * this is a segment that contains the middle of a
515 * higher-level PDU, but contains neither the beginning
516 * nor the end), or the subdissector couldn't dissect it
517 * all, as some data was missing (i.e., it set
518 * "pinfo->desegment_len" to the amount of additional
521 if (pinfo->desegment_offset == 0) {
523 * It couldn't, in fact, dissect any of it (the
524 * first byte it couldn't dissect is at an offset
525 * of "pinfo->desegment_offset" from the beginning
526 * of the payload, and that's 0).
527 * Just mark this as TCP.
529 if (check_col(pinfo->fd, COL_PROTOCOL)){
530 col_set_str(pinfo->fd, COL_PROTOCOL, "TCP");
532 if (check_col(pinfo->fd, COL_INFO)){
533 col_set_str(pinfo->fd, COL_INFO, "[Desegmented TCP]");
538 * Show what's left in the packet as data.
540 call_dissector(data_handle,tvb_new_subset(tvb, deseg_offset,-1,tvb_reported_length_remaining(tvb,deseg_offset)), pinfo, tree);
542 pinfo->can_desegment=0;
543 pinfo->desegment_offset = 0;
544 pinfo->desegment_len = 0;
551 tcp_info_append_uint(frame_data *fd, const char *abbrev, guint32 val)
553 if (check_col(fd, COL_INFO))
554 col_append_fstr(fd, COL_INFO, " %s=%u", abbrev, val);
558 dissect_tcpopt_maxseg(const ip_tcp_opt *optp, tvbuff_t *tvb,
559 int offset, guint optlen, frame_data *fd, proto_tree *opt_tree)
563 mss = tvb_get_ntohs(tvb, offset + 2);
564 proto_tree_add_text(opt_tree, tvb, offset, optlen,
565 "%s: %u bytes", optp->name, mss);
566 tcp_info_append_uint(fd, "MSS", mss);
570 dissect_tcpopt_wscale(const ip_tcp_opt *optp, tvbuff_t *tvb,
571 int offset, guint optlen, frame_data *fd, proto_tree *opt_tree)
575 ws = tvb_get_guint8(tvb, offset + 2);
576 proto_tree_add_text(opt_tree, tvb, offset, optlen,
577 "%s: %u bytes", optp->name, ws);
578 tcp_info_append_uint(fd, "WS", ws);
582 dissect_tcpopt_sack(const ip_tcp_opt *optp, tvbuff_t *tvb,
583 int offset, guint optlen, frame_data *fd, proto_tree *opt_tree)
585 proto_tree *field_tree = NULL;
587 guint leftedge, rightedge;
589 tf = proto_tree_add_text(opt_tree, tvb, offset, optlen, "%s:", optp->name);
590 offset += 2; /* skip past type and length */
591 optlen -= 2; /* subtract size of type and length */
593 if (field_tree == NULL) {
594 /* Haven't yet made a subtree out of this option. Do so. */
595 field_tree = proto_item_add_subtree(tf, *optp->subtree_index);
598 proto_tree_add_text(field_tree, tvb, offset, optlen,
599 "(suboption would go past end of option)");
602 leftedge = tvb_get_ntohl(tvb, offset);
605 proto_tree_add_text(field_tree, tvb, offset, optlen,
606 "(suboption would go past end of option)");
609 /* XXX - check whether it goes past end of packet */
610 rightedge = tvb_get_ntohl(tvb, offset + 4);
612 proto_tree_add_text(field_tree, tvb, offset, 8,
613 "left edge = %u, right edge = %u", leftedge, rightedge);
614 tcp_info_append_uint(fd, "SLE", leftedge);
615 tcp_info_append_uint(fd, "SRE", rightedge);
621 dissect_tcpopt_echo(const ip_tcp_opt *optp, tvbuff_t *tvb,
622 int offset, guint optlen, frame_data *fd, proto_tree *opt_tree)
626 echo = tvb_get_ntohl(tvb, offset + 2);
627 proto_tree_add_text(opt_tree, tvb, offset, optlen,
628 "%s: %u", optp->name, echo);
629 tcp_info_append_uint(fd, "ECHO", echo);
633 dissect_tcpopt_timestamp(const ip_tcp_opt *optp, tvbuff_t *tvb,
634 int offset, guint optlen, frame_data *fd, proto_tree *opt_tree)
638 tsv = tvb_get_ntohl(tvb, offset + 2);
639 tser = tvb_get_ntohl(tvb, offset + 6);
640 proto_tree_add_text(opt_tree, tvb, offset, optlen,
641 "%s: tsval %u, tsecr %u", optp->name, tsv, tser);
642 tcp_info_append_uint(fd, "TSV", tsv);
643 tcp_info_append_uint(fd, "TSER", tser);
647 dissect_tcpopt_cc(const ip_tcp_opt *optp, tvbuff_t *tvb,
648 int offset, guint optlen, frame_data *fd, proto_tree *opt_tree)
652 cc = tvb_get_ntohl(tvb, offset + 2);
653 proto_tree_add_text(opt_tree, tvb, offset, optlen,
654 "%s: %u", optp->name, cc);
655 tcp_info_append_uint(fd, "CC", cc);
658 static const ip_tcp_opt tcpopts[] = {
677 "Maximum segment size",
681 dissect_tcpopt_maxseg
689 dissect_tcpopt_wscale
702 &ett_tcp_option_sack,
729 dissect_tcpopt_timestamp
765 #define N_TCP_OPTS (sizeof tcpopts / sizeof tcpopts[0])
768 static const true_false_string flags_set_truth = {
774 /* Determine if there is a sub-dissector and call it. This has been */
775 /* separated into a stand alone routine to other protocol dissectors */
776 /* can call to it, ie. socks */
779 decode_tcp_ports(tvbuff_t *tvb, int offset, packet_info *pinfo,
780 proto_tree *tree, int src_port, int dst_port)
784 next_tvb = tvb_new_subset(tvb, offset, -1, -1);
786 /* determine if this packet is part of a conversation and call dissector */
787 /* for the conversation if available */
789 if (try_conversation_dissector(&pinfo->src, &pinfo->dst, PT_TCP,
790 src_port, dst_port, next_tvb, pinfo, tree))
793 /* do lookup with the subdissector table */
794 if (dissector_try_port(subdissector_table, src_port, next_tvb, pinfo, tree) ||
795 dissector_try_port(subdissector_table, dst_port, next_tvb, pinfo, tree))
798 /* do lookup with the heuristic subdissector table */
799 if (dissector_try_heuristic(heur_subdissector_list, next_tvb, pinfo, tree))
802 /* Oh, well, we don't know this; dissect it as data. */
803 call_dissector(data_handle,next_tvb, pinfo, tree);
808 dissect_tcp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
814 guint8 th_off_x2; /* combines th_off and th_x2 */
819 proto_tree *tcp_tree = NULL, *field_tree = NULL;
820 proto_item *ti = NULL, *tf;
822 gchar flags[64] = "<None>";
823 gchar *fstr[] = {"FIN", "SYN", "RST", "PSH", "ACK", "URG", "ECN", "CWR" };
834 guint16 computed_cksum;
835 guint length_remaining;
836 struct tcpinfo tcpinfo;
838 if (check_col(pinfo->fd, COL_PROTOCOL))
839 col_set_str(pinfo->fd, COL_PROTOCOL, "TCP");
841 /* Clear out the Info column. */
842 if (check_col(pinfo->fd, COL_INFO))
843 col_clear(pinfo->fd, COL_INFO);
845 th_sport = tvb_get_ntohs(tvb, offset);
846 th_dport = tvb_get_ntohs(tvb, offset + 2);
847 if (check_col(pinfo->fd, COL_INFO)) {
848 col_append_fstr(pinfo->fd, COL_INFO, "%s > %s",
849 get_tcp_port(th_sport), get_tcp_port(th_dport));
853 if (tcp_summary_in_tree) {
854 ti = proto_tree_add_protocol_format(tree, proto_tcp, tvb, 0,
856 "Transmission Control Protocol, Src Port: %s (%u), Dst Port: %s (%u)",
857 get_tcp_port(th_sport), th_sport,
858 get_tcp_port(th_dport), th_dport);
861 ti = proto_tree_add_item(tree, proto_tcp, tvb, 0,
862 tvb_length(tvb), FALSE);
864 tcp_tree = proto_item_add_subtree(ti, ett_tcp);
865 proto_tree_add_uint_format(tcp_tree, hf_tcp_srcport, tvb, offset, 2, th_sport,
866 "Source port: %s (%u)", get_tcp_port(th_sport), th_sport);
867 proto_tree_add_uint_format(tcp_tree, hf_tcp_dstport, tvb, offset + 2, 2, th_dport,
868 "Destination port: %s (%u)", get_tcp_port(th_dport), th_dport);
869 proto_tree_add_uint_hidden(tcp_tree, hf_tcp_port, tvb, offset, 2, th_sport);
870 proto_tree_add_uint_hidden(tcp_tree, hf_tcp_port, tvb, offset + 2, 2, th_dport);
873 th_seq = tvb_get_ntohl(tvb, offset + 4);
874 th_ack = tvb_get_ntohl(tvb, offset + 8);
875 th_off_x2 = tvb_get_guint8(tvb, offset + 12);
876 th_flags = tvb_get_guint8(tvb, offset + 13);
877 th_win = tvb_get_ntohs(tvb, offset + 14);
879 if (check_col(pinfo->fd, COL_INFO) || tree) {
880 for (i = 0; i < 8; i++) {
882 if (th_flags & bpos) {
884 strcpy(&flags[fpos], ", ");
887 strcpy(&flags[fpos], fstr[i]);
894 if (check_col(pinfo->fd, COL_INFO)) {
895 col_append_fstr(pinfo->fd, COL_INFO, " [%s] Seq=%u Ack=%u Win=%u",
896 flags, th_seq, th_ack, th_win);
900 if (tcp_summary_in_tree)
901 proto_item_append_text(ti, ", Seq: %u", th_seq);
902 proto_tree_add_uint(tcp_tree, hf_tcp_seq, tvb, offset + 4, 4, th_seq);
905 hlen = hi_nibble(th_off_x2) * 4; /* TCP header length, in bytes */
907 if (hlen < TCPH_MIN_LEN) {
908 /* Give up at this point; we put the source and destination port in
909 the tree, before fetching the header length, so that they'll
910 show up if this is in the failing packet in an ICMP error packet,
911 but it's now time to give up if the header length is bogus. */
912 if (check_col(pinfo->fd, COL_INFO))
913 col_append_fstr(pinfo->fd, COL_INFO, ", bogus TCP header length (%u, must be at least %u)",
916 proto_tree_add_uint_format(tcp_tree, hf_tcp_hdr_len, tvb, offset + 12, 1, hlen,
917 "Header length: %u bytes (bogus, must be at least %u)", hlen,
923 reported_len = tvb_reported_length(tvb);
924 len = tvb_length(tvb);
926 /* Compute the length of data in this segment. */
927 seglen = reported_len - hlen;
929 /* Compute the sequence number of next octet after this segment. */
930 nxtseq = th_seq + seglen;
933 if (tcp_summary_in_tree)
934 proto_item_append_text(ti, ", Ack: %u", th_ack);
935 proto_item_set_len(ti, hlen);
936 if (nxtseq != th_seq)
937 proto_tree_add_uint(tcp_tree, hf_tcp_nxtseq, tvb, offset, 0, nxtseq);
938 if (th_flags & TH_ACK)
939 proto_tree_add_uint(tcp_tree, hf_tcp_ack, tvb, offset + 8, 4, th_ack);
940 proto_tree_add_uint_format(tcp_tree, hf_tcp_hdr_len, tvb, offset + 12, 1, hlen,
941 "Header length: %u bytes", hlen);
942 tf = proto_tree_add_uint_format(tcp_tree, hf_tcp_flags, tvb, offset + 13, 1,
943 th_flags, "Flags: 0x%04x (%s)", th_flags, flags);
944 field_tree = proto_item_add_subtree(tf, ett_tcp_flags);
945 proto_tree_add_boolean(field_tree, hf_tcp_flags_cwr, tvb, offset + 13, 1, th_flags);
946 proto_tree_add_boolean(field_tree, hf_tcp_flags_ecn, tvb, offset + 13, 1, th_flags);
947 proto_tree_add_boolean(field_tree, hf_tcp_flags_urg, tvb, offset + 13, 1, th_flags);
948 proto_tree_add_boolean(field_tree, hf_tcp_flags_ack, tvb, offset + 13, 1, th_flags);
949 proto_tree_add_boolean(field_tree, hf_tcp_flags_push, tvb, offset + 13, 1, th_flags);
950 proto_tree_add_boolean(field_tree, hf_tcp_flags_reset, tvb, offset + 13, 1, th_flags);
951 proto_tree_add_boolean(field_tree, hf_tcp_flags_syn, tvb, offset + 13, 1, th_flags);
952 proto_tree_add_boolean(field_tree, hf_tcp_flags_fin, tvb, offset + 13, 1, th_flags);
953 proto_tree_add_uint(tcp_tree, hf_tcp_window_size, tvb, offset + 14, 2, th_win);
956 /* Assume we'll pass un-reassembled data to subdissectors. */
957 tcpinfo.is_reassembled = FALSE;
959 pinfo->private_data = &tcpinfo;
962 * Assume, initially, that we can't desegment.
964 pinfo->can_desegment = 0;
966 th_sum = tvb_get_ntohs(tvb, offset + 16);
967 if (!pinfo->fragmented && len >= reported_len) {
968 /* The packet isn't part of a fragmented datagram, isn't being
969 returned inside an ICMP error packet, and isn't truncated, so we
971 XXX - make a bigger scatter-gather list once we do fragment
974 /* Set up the fields of the pseudo-header. */
975 cksum_vec[0].ptr = pinfo->src.data;
976 cksum_vec[0].len = pinfo->src.len;
977 cksum_vec[1].ptr = pinfo->dst.data;
978 cksum_vec[1].len = pinfo->dst.len;
979 cksum_vec[2].ptr = (const guint8 *)&phdr;
980 switch (pinfo->src.type) {
983 phdr[0] = htonl((IP_PROTO_TCP<<16) + reported_len);
984 cksum_vec[2].len = 4;
988 phdr[0] = htonl(reported_len);
989 phdr[1] = htonl(IP_PROTO_TCP);
990 cksum_vec[2].len = 8;
994 /* TCP runs only atop IPv4 and IPv6.... */
995 g_assert_not_reached();
998 cksum_vec[3].ptr = tvb_get_ptr(tvb, offset, len);
999 cksum_vec[3].len = reported_len;
1000 computed_cksum = in_cksum(&cksum_vec[0], 4);
1001 if (computed_cksum == 0) {
1003 * We have all the data for this TCP segment, and the checksum of
1004 * the header and the data is good, so we can desegment it.
1005 * Is desegmentation enabled?
1007 if (tcp_desegment) {
1008 /* Yes - is this segment being returned in an error packet? */
1009 if (!pinfo->in_error_pkt) {
1010 /* No - indicate that we will desegment.
1011 We do NOT want to desegment segments returned in error
1012 packets, as they're not part of a TCP connection. */
1013 pinfo->can_desegment = 2;
1016 proto_tree_add_uint_format(tcp_tree, hf_tcp_checksum, tvb,
1017 offset + 16, 2, th_sum, "Checksum: 0x%04x (correct)", th_sum);
1019 proto_tree_add_boolean_hidden(tcp_tree, hf_tcp_checksum_bad, tvb,
1020 offset + 16, 2, TRUE);
1021 proto_tree_add_uint_format(tcp_tree, hf_tcp_checksum, tvb,
1022 offset + 16, 2, th_sum,
1023 "Checksum: 0x%04x (incorrect, should be 0x%04x)", th_sum,
1024 in_cksum_shouldbe(th_sum, computed_cksum));
1027 proto_tree_add_uint_format(tcp_tree, hf_tcp_checksum, tvb,
1028 offset + 16, 2, th_sum, "Checksum: 0x%04x", th_sum);
1030 if (th_flags & TH_URG) {
1031 th_urp = tvb_get_ntohs(tvb, offset + 18);
1032 /* Export the urgent pointer, for the benefit of protocols such as
1034 tcpinfo.urgent = TRUE;
1035 tcpinfo.urgent_pointer = th_urp;
1036 if (check_col(pinfo->fd, COL_INFO))
1037 col_append_fstr(pinfo->fd, COL_INFO, " Urg=%u", th_urp);
1038 if (tcp_tree != NULL)
1039 proto_tree_add_uint(tcp_tree, hf_tcp_urgent_pointer, tvb, offset + 18, 2, th_urp);
1041 tcpinfo.urgent = FALSE;
1043 if (check_col(pinfo->fd, COL_INFO))
1044 col_append_fstr(pinfo->fd, COL_INFO, " Len=%d", seglen);
1046 /* Decode TCP options, if any. */
1047 if (tree && hlen > TCPH_MIN_LEN) {
1048 /* There's more than just the fixed-length header. Decode the
1050 optlen = hlen - TCPH_MIN_LEN; /* length of options, in bytes */
1051 tf = proto_tree_add_text(tcp_tree, tvb, offset + 20, optlen,
1052 "Options: (%d bytes)", optlen);
1053 field_tree = proto_item_add_subtree(tf, ett_tcp_options);
1054 dissect_ip_tcp_options(tvb, offset + 20, optlen,
1055 tcpopts, N_TCP_OPTS, TCPOPT_EOL, pinfo->fd, field_tree);
1058 /* Skip over header + options */
1061 pinfo->ptype = PT_TCP;
1062 pinfo->srcport = th_sport;
1063 pinfo->destport = th_dport;
1065 /* Check the packet length to see if there's more data
1066 (it could be an ACK-only packet) */
1067 length_remaining = tvb_length_remaining(tvb, offset);
1068 if (length_remaining != 0) {
1069 if (th_flags & TH_RST) {
1073 * 4.2.2.12 RST Segment: RFC-793 Section 3.4
1075 * A TCP SHOULD allow a received RST segment to include data.
1078 * It has been suggested that a RST segment could contain
1079 * ASCII text that encoded and explained the cause of the
1080 * RST. No standard has yet been established for such
1083 * so for segments with RST we just display the data as text.
1085 proto_tree_add_text(tcp_tree, tvb, offset, length_remaining,
1087 tvb_format_text(tvb, offset, length_remaining));
1089 /* Can we desegment this segment? */
1090 if (pinfo->can_desegment) {
1092 desegment_tcp(tvb, pinfo, offset, th_seq, nxtseq, th_sport, th_dport, tree, tcp_tree);
1094 /* No - just call the subdissector. */
1095 decode_tcp_ports(tvb, offset, pinfo, tree, th_sport, th_dport);
1100 if( data_out_file ) {
1101 reassemble_tcp( th_seq, /* sequence number */
1102 seglen, /* data length */
1103 tvb_get_ptr(tvb, offset, length_remaining), /* data */
1104 length_remaining, /* captured data length */
1105 ( th_flags & TH_SYN ), /* is syn set? */
1114 proto_register_tcp(void)
1116 static hf_register_info hf[] = {
1119 { "Source Port", "tcp.srcport", FT_UINT16, BASE_DEC, NULL, 0x0,
1123 { "Destination Port", "tcp.dstport", FT_UINT16, BASE_DEC, NULL, 0x0,
1127 { "Source or Destination Port", "tcp.port", FT_UINT16, BASE_DEC, NULL, 0x0,
1131 { "Sequence number", "tcp.seq", FT_UINT32, BASE_DEC, NULL, 0x0,
1135 { "Next sequence number", "tcp.nxtseq", FT_UINT32, BASE_DEC, NULL, 0x0,
1139 { "Acknowledgement number", "tcp.ack", FT_UINT32, BASE_DEC, NULL, 0x0,
1143 { "Header Length", "tcp.hdr_len", FT_UINT8, BASE_DEC, NULL, 0x0,
1147 { "Flags", "tcp.flags", FT_UINT8, BASE_HEX, NULL, 0x0,
1150 { &hf_tcp_flags_cwr,
1151 { "Congestion Window Reduced (CWR)", "tcp.flags.cwr", FT_BOOLEAN, 8, TFS(&flags_set_truth), TH_CWR,
1154 { &hf_tcp_flags_ecn,
1155 { "ECN-Echo", "tcp.flags.ecn", FT_BOOLEAN, 8, TFS(&flags_set_truth), TH_ECN,
1158 { &hf_tcp_flags_urg,
1159 { "Urgent", "tcp.flags.urg", FT_BOOLEAN, 8, TFS(&flags_set_truth), TH_URG,
1162 { &hf_tcp_flags_ack,
1163 { "Acknowledgment", "tcp.flags.ack", FT_BOOLEAN, 8, TFS(&flags_set_truth), TH_ACK,
1166 { &hf_tcp_flags_push,
1167 { "Push", "tcp.flags.push", FT_BOOLEAN, 8, TFS(&flags_set_truth), TH_PUSH,
1170 { &hf_tcp_flags_reset,
1171 { "Reset", "tcp.flags.reset", FT_BOOLEAN, 8, TFS(&flags_set_truth), TH_RST,
1174 { &hf_tcp_flags_syn,
1175 { "Syn", "tcp.flags.syn", FT_BOOLEAN, 8, TFS(&flags_set_truth), TH_SYN,
1178 { &hf_tcp_flags_fin,
1179 { "Fin", "tcp.flags.fin", FT_BOOLEAN, 8, TFS(&flags_set_truth), TH_FIN,
1182 { &hf_tcp_window_size,
1183 { "Window size", "tcp.window_size", FT_UINT16, BASE_DEC, NULL, 0x0,
1187 { "Checksum", "tcp.checksum", FT_UINT16, BASE_HEX, NULL, 0x0,
1190 { &hf_tcp_checksum_bad,
1191 { "Bad Checksum", "tcp.checksum_bad", FT_BOOLEAN, BASE_NONE, NULL, 0x0,
1194 { &hf_tcp_urgent_pointer,
1195 { "Urgent pointer", "tcp.urgent_pointer", FT_UINT16, BASE_DEC, NULL, 0x0,
1198 static gint *ett[] = {
1202 &ett_tcp_option_sack,
1205 module_t *tcp_module;
1207 proto_tcp = proto_register_protocol("Transmission Control Protocol",
1209 proto_register_field_array(proto_tcp, hf, array_length(hf));
1210 proto_register_subtree_array(ett, array_length(ett));
1212 /* subdissector code */
1213 subdissector_table = register_dissector_table("tcp.port");
1214 register_heur_dissector_list("tcp", &heur_subdissector_list);
1216 /* Register configuration preferences */
1217 tcp_module = prefs_register_protocol(proto_tcp, NULL);
1218 prefs_register_bool_preference(tcp_module, "tcp_summary_in_tree",
1219 "Show TCP summary in protocol tree",
1220 "Whether the TCP summary line should be shown in the protocol tree",
1221 &tcp_summary_in_tree);
1222 prefs_register_bool_preference(tcp_module, "desegment_tcp_streams",
1223 "Allow subdissector to desegment TCP streams",
1224 "Whether subdissector can request TCP streams to be desegmented",
1227 register_init_routine(tcp_desegment_init);
1228 register_init_routine(tcp_fragment_init);
1232 proto_reg_handoff_tcp(void)
1234 dissector_handle_t tcp_handle;
1236 tcp_handle = create_dissector_handle(dissect_tcp, proto_tcp);
1237 dissector_add("ip.proto", IP_PROTO_TCP, tcp_handle);
1238 data_handle = find_dissector("data");