2 * Routines for Token-Ring packet disassembly
3 * Gilbert Ramirez <gram@xiexie.org>
5 * $Id: packet-tr.c,v 1.45 2000/08/07 03:21:17 guy Exp $
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.
31 #ifdef HAVE_SYS_TYPES_H
32 # include <sys/types.h>
38 #include "packet-tr.h"
39 #include "packet-llc.h"
40 #include "packet-trmac.h"
42 static int proto_tr = -1;
43 static int hf_tr_dst = -1;
44 static int hf_tr_src = -1;
45 static int hf_tr_addr = -1;
46 static int hf_tr_sr = -1;
47 static int hf_tr_ac = -1;
48 static int hf_tr_priority = -1;
49 static int hf_tr_frame = -1;
50 static int hf_tr_monitor_cnt = -1;
51 static int hf_tr_priority_reservation = -1;
52 static int hf_tr_fc = -1;
53 static int hf_tr_fc_type = -1;
54 static int hf_tr_fc_pcf = -1;
55 static int hf_tr_rif_bytes = -1;
56 static int hf_tr_broadcast = -1;
57 static int hf_tr_max_frame_size = -1;
58 static int hf_tr_direction = -1;
59 static int hf_tr_rif = -1;
60 static int hf_tr_rif_ring = -1;
61 static int hf_tr_rif_bridge = -1;
63 static gint ett_token_ring = -1;
64 static gint ett_token_ring_ac = -1;
65 static gint ett_token_ring_fc = -1;
67 #define TR_MIN_HEADER_LEN 14
68 #define TR_MAX_HEADER_LEN 32
70 static const true_false_string ac_truth = { "Frame", "Token" };
72 static const value_string pcf_vals[] = {
73 { 0, "Normal buffer" },
74 { 1, "Express buffer" },
78 { 5, "Active Monitor Present" },
79 { 6, "Standby Monitor Present" },
83 static const value_string frame_vals[] = {
90 static const value_string broadcast_vals[] = {
91 { 0 << 5, "Non-broadcast" },
92 { 1 << 5, "Non-broadcast" },
93 { 2 << 5, "Non-broadcast" },
94 { 3 << 5, "Non-broadcast" },
95 { 4 << 5, "All-routes broadcast" },
96 { 5 << 5, "All-routes broadcast" },
97 { 6 << 5, "Single-route broadcast" },
98 { 7 << 5, "Single-route broadcast" },
102 static const value_string max_frame_size_vals[] = {
113 static const value_string direction_vals[] = {
114 { 0, "From originating station (-->)" },
115 { 128, "To originating station (<--)" },
120 * DODGY LINUX HACK DODGY LINUX HACK
121 * Linux 2.0.x always passes frames to the Token Ring driver for transmission with
122 * 18 bytes padding for source routing information. Some drivers copy the first
123 * (18 - srlen) bytes up the frame (18 - srlen) bytes thus removing the padding.
124 * Other drivers just make a copy of the entire frame and then hack about with it
125 * so the frame the sniffer gets is fine (just has extra sr routing).
126 * In the first instance (driver hacking frame in situ) the sniffer gets a garbled
128 * This function trys to detect this and returns the offset of where
129 * the frame really starts.
130 * This only detects frames that we have sent ourselves so if we are packet sniffing
131 * on the machine we are watching this is useful.
132 * Compare offset 0 with offset x+1 for a length of x bytes for all value of x = 1 to 18
133 * if match then Linux driver has done in situ source route compression of the crappy
134 * Linux 2.0.x frame so the beginning of the real frame is x bytes in.
135 * (And this real frame x bytes in looks like a proper TR frame that goes on the wire
136 * with none of the Linux idiosyncrasies).
138 int check_for_old_linux_tvb(tvbuff_t *tvb)
143 /* Restrict our looping to the boundaries of the frame */
144 bytes = tvb_length(tvb);
149 data = tvb_get_ptr(tvb, 0, bytes);
151 for(x = 1; x <= bytes-1 ;x++)
153 if (memcmp(&data[0], &data[x], x) == 0)
161 int check_for_old_linux(const u_char * pd)
166 if (memcmp(&pd[0],&pd[x],x) == 0)
176 add_ring_bridge_pairs(int rcf_len, tvbuff_t*, proto_tree *tree);
179 capture_tr(const u_char *pd, int offset, packet_counts *ld) {
181 int source_routed = 0;
184 guint8 trn_rif_bytes;
185 guint8 actual_rif_bytes;
187 /* The trn_hdr struct, as separate variables */
188 guint8 trn_fc; /* field control field */
189 const guint8 *trn_shost; /* source host */
191 if (!BYTES_ARE_IN_FRAME(offset, TR_MIN_HEADER_LEN)) {
196 if ((x = check_for_old_linux(pd)))
198 /* Actually packet starts x bytes into what we have got but with all
199 source routing compressed
201 /* pd = &pd[x]; */ offset+=x;
205 trn_fc = pd[offset + 1];
206 trn_shost = &pd[offset + 8];
208 frame_type = (trn_fc & 192) >> 6;
210 /* if the high bit on the first byte of src hwaddr is 1, then
211 this packet is source-routed */
212 source_routed = trn_shost[0] & 128;
214 trn_rif_bytes = pd[offset + 14] & 31;
216 /* sometimes we have a RCF but no RIF... half source-routed? */
217 if (!source_routed && trn_rif_bytes > 0) {
218 /* I'll check for 2 bytes of RIF and mark the packet as source
219 * routed even though I'm not sure _what_ that kind of packet is */
220 if (trn_rif_bytes == 2) {
223 /* the Linux 2.0 TR code strips source-route bits in
224 * order to test for SR. This can be removed from most
225 * packets with oltr, but not all. So, I try to figure out
226 * which packets should have been SR here. I'll check to
227 * see if there's a SNAP or IPX field right after
231 pd[offset + 0x0e + trn_rif_bytes] == 0xaa &&
232 pd[offset + 0x0f + trn_rif_bytes] == 0xaa &&
233 pd[offset + 0x10 + trn_rif_bytes] == 0x03) ||
235 pd[offset + 0x0e + trn_rif_bytes] == 0xe0 &&
236 pd[offset + 0x0f + trn_rif_bytes] == 0xe0) ) {
244 actual_rif_bytes = trn_rif_bytes;
248 actual_rif_bytes = 0;
251 /* this is a silly hack for Linux 2.0.x. Read the comment below,
252 in front of the other #ifdef linux. If we're sniffing our own NIC,
253 we get a full RIF, sometimes with garbage */
254 if ((source_routed && trn_rif_bytes == 2 && frame_type == 1) ||
255 (!source_routed && frame_type == 1)) {
256 /* look for SNAP or IPX only */
257 if ( (pd[offset + 0x20] == 0xaa && pd[offset + 0x21] == 0xaa && pd[offset + 0x22] == 03) ||
258 (pd[offset + 0x20] == 0xe0 && pd[offset + 0x21] == 0xe0) ) {
259 actual_rif_bytes = 18;
261 pd[offset + 0x23] == 0 &&
262 pd[offset + 0x24] == 0 &&
263 pd[offset + 0x25] == 0 &&
264 pd[offset + 0x26] == 0x00 &&
265 pd[offset + 0x27] == 0x11) {
267 actual_rif_bytes = 18;
269 /* Linux 2.0.x also requires drivers pass up a fake SNAP and LLC header before th
270 real LLC hdr for all Token Ring frames that arrive with DSAP and SSAP != 0xAA
271 (i.e. for non SNAP frames e.g. for Netware frames)
272 the fake SNAP header has the ETH_P_TR_802_2 ether type (0x0011) and the protocol id
273 bytes as zero frame looks like :-
274 TR Header | Fake LLC | Fake SNAP | Wire LLC | Rest of data */
275 offset += 8; /* Skip fake LLC and SNAP */
279 offset += actual_rif_bytes + TR_MIN_HEADER_LEN;
281 /* The package is either MAC or LLC */
282 switch (frame_type) {
288 capture_llc(pd, offset, ld);
291 /* non-MAC, non-LLC, i.e., "Reserved" */
299 dissect_tr(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
301 proto_tree *tr_tree, *bf_tree;
307 volatile int fixoffset = 0;
308 volatile int source_routed = 0;
309 volatile guint8 trn_rif_bytes;
310 volatile guint8 actual_rif_bytes;
312 /* I make tr_tvb static because I need to set it before any TRY block.
313 * If tr_tvb were not static, the possibility exists that the value
314 * I give to tr_tvb would be clobbered. */
315 static tvbuff_t *tr_tvb = NULL;
317 /* The trn_hdr struct, as separate variables */
318 guint8 trn_ac; /* access control field */
319 guint8 trn_fc; /* field control field */
320 const guint8 *trn_dhost; /* destination host */
321 const guint8 *trn_shost; /* source host */
323 /* non-source-routed version of source addr */
324 static guint8 trn_shost_nonsr[6];
327 /* Token-Ring Strings */
328 char *fc[] = { "MAC", "LLC", "Reserved", "Unknown" };
330 pinfo->current_proto = "Token-Ring";
332 if (check_col(pinfo->fd, COL_PROTOCOL))
333 col_add_str(pinfo->fd, COL_PROTOCOL, "TR");
335 if ((x = check_for_old_linux_tvb((tvbuff_t*) tvb))) {
336 /* Actually packet starts x bytes into what we have got but with all
337 source routing compressed. See comment above */
338 tr_tvb = tvb_new_subset((tvbuff_t*) tvb, x, -1, -1);
345 trn_fc = tvb_get_guint8(tr_tvb, 1);
346 trn_dhost = tvb_get_ptr(tr_tvb, 2, 6);
347 trn_shost = tvb_get_ptr(tr_tvb, 8, 6);
350 memcpy(trn_shost_nonsr, trn_shost, 6);
351 trn_shost_nonsr[0] &= 127;
352 frame_type = (trn_fc & 192) >> 6;
354 if (check_col(pinfo->fd, COL_INFO))
355 col_add_fstr(pinfo->fd, COL_INFO, "Token-Ring %s", fc[frame_type]);
357 /* if the high bit on the first byte of src hwaddr is 1, then
358 this packet is source-routed */
359 source_routed = trn_shost[0] & 128;
361 trn_rif_bytes = tvb_get_guint8(tr_tvb, 14) & 31;
363 /* sometimes we have a RCF but no RIF... half source-routed? */
364 /* I'll check for 2 bytes of RIF and the 0x70 byte */
365 if (!source_routed && trn_rif_bytes > 0) {
366 if (trn_rif_bytes == 2) {
369 /* the Linux 2.0 TR code strips source-route bits in
370 * order to test for SR. This can be removed from most
371 * packets with oltr, but not all. So, I try to figure out
372 * which packets should have been SR here. I'll check to
373 * see if there's a SNAP or IPX field right after
378 if ( ( tvb_get_ntohs(tr_tvb, trn_rif_bytes + 0x0e) == 0xaaaa &&
379 tvb_get_guint8(tr_tvb, trn_rif_bytes + 0x10) == 0x03) ||
381 tvb_get_ntohs(tr_tvb, trn_rif_bytes + 0x0e) == 0xe0e0 ) {
387 /* We had no information beyond the TR header. Just assume
388 * this is a normal (non-Linux) TR header. */
396 actual_rif_bytes = trn_rif_bytes;
400 actual_rif_bytes = 0;
403 /* this is a silly hack for Linux 2.0.x. Read the comment below,
404 in front of the other #ifdef linux. If we're sniffing our own NIC,
405 we get a full RIF, sometimes with garbage */
407 if ((source_routed && trn_rif_bytes == 2 && frame_type == 1) ||
408 (!source_routed && frame_type == 1)) {
409 /* look for SNAP or IPX only */
411 (tvb_get_ntohs(tr_tvb, 0x20) == 0xaaaa &&
412 tvb_get_guint8(tr_tvb, 0x22) == 0x03)
414 tvb_get_ntohs(tr_tvb, 0x20) == 0xe0e0 ) {
416 actual_rif_bytes = 18;
419 tvb_get_ntohl(tr_tvb, 0x23) == 0 &&
420 tvb_get_guint8(tr_tvb, 0x27) == 0x11) {
422 actual_rif_bytes = 18;
424 /* Linux 2.0.x also requires drivers pass up a fake SNAP and LLC header before th
425 real LLC hdr for all Token Ring frames that arrive with DSAP and SSAP != 0xAA
426 (i.e. for non SNAP frames e.g. for Netware frames)
427 the fake SNAP header has the ETH_P_TR_802_2 ether type (0x0011) and the protocol id
428 bytes as zero frame looks like :-
429 TR Header | Fake LLC | Fake SNAP | Wire LLC | Rest of data */
430 fixoffset += 8; /* Skip fake LLC and SNAP */
435 /* We had no information beyond the TR header. Just assume
436 * this is a normal (non-Linux) TR header. */
442 /* XXX - copy it to some buffer associated with "pi", rather than
443 just making "trn_shost_nonsr" static? */
444 SET_ADDRESS(&pi.dl_src, AT_ETHER, 6, trn_shost_nonsr);
445 SET_ADDRESS(&pi.src, AT_ETHER, 6, trn_shost_nonsr);
446 SET_ADDRESS(&pi.dl_dst, AT_ETHER, 6, trn_dhost);
447 SET_ADDRESS(&pi.dst, AT_ETHER, 6, trn_dhost);
449 /* protocol analysis tree */
451 /* Create Token-Ring Tree */
452 ti = proto_tree_add_item(tree, proto_tr, tr_tvb, 0, TR_MIN_HEADER_LEN + actual_rif_bytes, FALSE);
453 tr_tree = proto_item_add_subtree(ti, ett_token_ring);
455 /* Create the Access Control bitfield tree */
456 trn_ac = tvb_get_guint8(tr_tvb, 0);
457 ti = proto_tree_add_uint(tr_tree, hf_tr_ac, tr_tvb, 0, 1, trn_ac);
458 bf_tree = proto_item_add_subtree(ti, ett_token_ring_ac);
460 proto_tree_add_uint(bf_tree, hf_tr_priority, tr_tvb, 0, 1, trn_ac);
461 proto_tree_add_boolean(bf_tree, hf_tr_frame, tr_tvb, 0, 1, trn_ac);
462 proto_tree_add_uint(bf_tree, hf_tr_monitor_cnt, tr_tvb, 0, 1, trn_ac);
463 proto_tree_add_uint(bf_tree, hf_tr_priority_reservation, tr_tvb, 0, 1, trn_ac);
465 /* Create the Frame Control bitfield tree */
466 ti = proto_tree_add_uint(tr_tree, hf_tr_fc, tr_tvb, 1, 1, trn_fc);
467 bf_tree = proto_item_add_subtree(ti, ett_token_ring_fc);
469 proto_tree_add_uint(bf_tree, hf_tr_fc_type, tr_tvb, 1, 1, trn_fc);
470 proto_tree_add_uint(bf_tree, hf_tr_fc_pcf, tr_tvb, 1, 1, trn_fc);
471 proto_tree_add_ether(tr_tree, hf_tr_dst, tr_tvb, 2, 6, trn_dhost);
472 proto_tree_add_ether(tr_tree, hf_tr_src, tr_tvb, 8, 6, trn_shost);
473 proto_tree_add_ether_hidden(tr_tree, hf_tr_addr, tr_tvb, 2, 6, trn_dhost);
474 proto_tree_add_ether_hidden(tr_tree, hf_tr_addr, tr_tvb, 8, 6, trn_shost);
476 proto_tree_add_boolean(tr_tree, hf_tr_sr, tr_tvb, 8, 1, source_routed);
478 /* non-source-routed version of src addr */
479 proto_tree_add_ether_hidden(tr_tree, hf_tr_src, tr_tvb, 8, 6, trn_shost_nonsr);
483 rcf1 = tvb_get_guint8(tr_tvb, 14);
484 proto_tree_add_uint(tr_tree, hf_tr_rif_bytes, tr_tvb, 14, 1, trn_rif_bytes);
485 proto_tree_add_uint(tr_tree, hf_tr_broadcast, tr_tvb, 14, 1, rcf1 & 224);
488 rcf2 = tvb_get_guint8(tr_tvb, 15);
489 proto_tree_add_uint(tr_tree, hf_tr_max_frame_size, tr_tvb, 15, 1, rcf2 & 112);
490 proto_tree_add_uint(tr_tree, hf_tr_direction, tr_tvb, 15, 1, rcf2 & 128);
492 /* if we have more than 2 bytes of RIF, then we have
494 if (trn_rif_bytes > 2) {
495 add_ring_bridge_pairs(trn_rif_bytes, tr_tvb, tr_tree);
499 /* Linux 2.0.x has a problem in that the 802.5 code creates
500 an emtpy full (18-byte) RIF area. It's up to the tr driver to
501 either fill it in or remove it before sending the bytes out
502 to the wire. If you run tcpdump on a Linux 2.0.x machine running
503 token-ring, tcpdump will capture these 18 filler bytes. They
504 are filled with garbage. The best way to detect this problem is
505 to know the src hwaddr of the machine from which you were running
506 tcpdump. W/o that, however, I'm guessing that DSAP == SSAP if the
507 frame type is LLC. It's very much a hack. */
508 if (actual_rif_bytes > trn_rif_bytes) {
509 proto_tree_add_text(tr_tree, tr_tvb, TR_MIN_HEADER_LEN + trn_rif_bytes, actual_rif_bytes - trn_rif_bytes,
510 "Empty RIF from Linux 2.0.x driver. The sniffing NIC "
511 "is also running a protocol stack.");
514 proto_tree_add_text(tr_tree, tr_tvb, TR_MIN_HEADER_LEN + 18,8,"Linux 2.0.x fake LLC and SNAP header");
518 next_tvb = tvb_new_subset(tr_tvb, TR_MIN_HEADER_LEN + actual_rif_bytes + fixoffset, -1, -1);
520 /* The package is either MAC or LLC */
521 switch (frame_type) {
524 dissect_trmac(next_tvb, pinfo, tree);
527 dissect_llc(next_tvb, pinfo, tree);
530 /* non-MAC, non-LLC, i.e., "Reserved" */
531 dissect_data(next_tvb, pinfo, tree);
536 /* this routine is taken from the Linux net/802/tr.c code, which shows
537 ring-bridge pairs in the /proc/net/tr_rif virtual file. */
539 add_ring_bridge_pairs(int rcf_len, tvbuff_t *tvb, proto_tree *tree)
542 int segment, brdgnmb, unprocessed_rif;
545 #define RIF_OFFSET 16
546 #define RIF_BYTES_TO_PROCESS 30
548 char buffer[3 + (RIF_BYTES_TO_PROCESS / 2) * 6 + 1];
550 /* Only process so many bytes of RIF, as per TR spec, and not overflow
551 * static buffer above */
552 unprocessed_rif = rcf_len - RIF_BYTES_TO_PROCESS;
553 rcf_len = MIN(rcf_len, RIF_BYTES_TO_PROCESS);
555 /* Ignore the 2 RCF bytes, since they don't make up the ring/bride pairs */
558 for(j = 1; j < rcf_len - 1; j += 2) {
560 segment = tvb_get_ntohs(tvb, RIF_OFFSET) >> 4;
561 size = sprintf(buffer, "%03X",segment);
562 proto_tree_add_uint_hidden(tree, hf_tr_rif_ring, tvb, TR_MIN_HEADER_LEN + 2, 2, segment);
565 segment = tvb_get_ntohs(tvb, RIF_OFFSET + 1 + j) >> 4;
566 brdgnmb = tvb_get_guint8(tvb, RIF_OFFSET + j) & 0x0f;
567 size = sprintf(buffer+buff_offset, "-%01X-%03X",brdgnmb,segment);
568 proto_tree_add_uint_hidden(tree, hf_tr_rif_ring, tvb, TR_MIN_HEADER_LEN + 3 + j, 2, segment);
569 proto_tree_add_uint_hidden(tree, hf_tr_rif_bridge, tvb, TR_MIN_HEADER_LEN + 2 + j, 1, brdgnmb);
572 proto_tree_add_string(tree, hf_tr_rif, tvb, TR_MIN_HEADER_LEN + 2, rcf_len, buffer);
574 if (unprocessed_rif > 0) {
575 proto_tree_add_text(tree, tvb, TR_MIN_HEADER_LEN + RIF_BYTES_TO_PROCESS, unprocessed_rif,
576 "Extra RIF bytes beyond spec: %d", unprocessed_rif);
581 proto_register_tr(void)
583 static hf_register_info hf[] = {
585 { "Access Control", "tr.ac", FT_UINT8, BASE_HEX, NULL, 0x0,
589 { "Priority", "tr.priority", FT_UINT8, BASE_DEC, NULL, 0xe0,
593 { "Frame", "tr.frame", FT_BOOLEAN, 8, TFS(&ac_truth), 0x10,
596 { &hf_tr_monitor_cnt,
597 { "Monitor Count", "tr.monitor_cnt", FT_UINT8, BASE_DEC, NULL, 0x08,
600 { &hf_tr_priority_reservation,
601 { "Priority Reservation","tr.priority_reservation", FT_UINT8, BASE_DEC, NULL, 0x07,
605 { "Frame Control", "tr.fc", FT_UINT8, BASE_HEX, NULL, 0x0,
609 { "Frame Type", "tr.frame_type", FT_UINT8, BASE_DEC, VALS(frame_vals), 0xc0,
613 { "Frame PCF", "tr.frame_pcf", FT_UINT8, BASE_DEC, VALS(pcf_vals), 0x0f,
617 { "Destination", "tr.dst", FT_ETHER, BASE_NONE, NULL, 0x0,
618 "Destination Hardware Address" }},
621 { "Source", "tr.src", FT_ETHER, BASE_NONE, NULL, 0x0,
622 "Source Hardware Address" }},
625 { "Source or Destination Address", "tr.addr", FT_ETHER, BASE_NONE, NULL, 0x0,
626 "Source or Destination Hardware Address" }},
629 { "Source Routed", "tr.sr", FT_BOOLEAN, BASE_NONE, NULL, 0x0,
633 { "RIF Bytes", "tr.rif_bytes", FT_UINT8, BASE_DEC, NULL, 0x0,
634 "Number of bytes in Routing Information Fields, including "
635 "the two bytes of Routing Control Field" }},
638 { "Broadcast Type", "tr.broadcast", FT_UINT8, BASE_DEC, VALS(broadcast_vals), 0x0,
639 "Type of Token-Ring Broadcast" }},
641 { &hf_tr_max_frame_size,
642 { "Maximum Frame Size", "tr.max_frame_size", FT_UINT8, BASE_DEC, VALS(max_frame_size_vals),
647 { "Direction", "tr.direction", FT_UINT8, BASE_DEC, VALS(direction_vals), 0x0,
648 "Direction of RIF" }},
651 { "Ring-Bridge Pairs", "tr.rif", FT_STRING, BASE_NONE, NULL, 0x0,
652 "String representing Ring-Bridge Pairs" }},
655 { "RIF Ring", "tr.rif.ring", FT_UINT16, BASE_HEX, NULL, 0x0,
659 { "RIF Bridge", "tr.rif.bridge", FT_UINT8, BASE_HEX, NULL, 0x0,
662 static gint *ett[] = {
668 proto_tr = proto_register_protocol("Token-Ring", "tr");
669 proto_register_field_array(proto_tr, hf, array_length(hf));
670 proto_register_subtree_array(ett, array_length(ett));