2 * Routines for IEEE 802.2 LLC layer
3 * Gilbert Ramirez <gram@alumni.rice.edu>
5 * $Id: packet-llc.c,v 1.93 2001/12/10 00:25:30 guy Exp $
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.
30 #ifdef HAVE_SYS_TYPES_H
31 # include <sys/types.h>
40 #include "bridged_pids.h"
41 #include "packet-ip.h"
42 #include "packet-ipx.h"
43 #include "packet-netbios.h"
44 #include "sna-utils.h"
46 #include "packet-llc.h"
48 static int proto_llc = -1;
49 static int hf_llc_dsap = -1;
50 static int hf_llc_ssap = -1;
51 static int hf_llc_dsap_ig = -1;
52 static int hf_llc_ssap_cr = -1;
53 static int hf_llc_ctrl = -1;
54 static int hf_llc_type = -1;
55 static int hf_llc_oui = -1;
56 static int hf_llc_pid = -1;
58 static gint ett_llc = -1;
59 static gint ett_llc_ctrl = -1;
61 static dissector_table_t subdissector_table;
62 static dissector_table_t cisco_subdissector_table;
64 static dissector_handle_t bpdu_handle;
65 static dissector_handle_t eth_handle;
66 static dissector_handle_t fddi_handle;
67 static dissector_handle_t tr_handle;
68 static dissector_handle_t data_handle;
70 typedef void (capture_func_t)(const u_char *, int, int, packet_counts *);
72 /* The SAP info is split into two tables, one value_string table and one
73 * table of sap_info. This is so that the value_string can be used in the
74 * header field registration.
78 capture_func_t *capture_func;
82 * Group/Individual bit, in the DSAP.
84 #define DSAP_GI_BIT 0x01
87 * Command/Response bit, in the SSAP.
89 * The low-order bit of the SSAP apparently determines whether this
90 * is a request or a response. (RFC 1390, "Transmission of IP and
91 * ARP over FDDI Networks", says
93 * Command frames are identified by having the low order
94 * bit of the SSAP address reset to zero. Response frames
95 * have the low order bit of the SSAP address set to one.
97 * and a page I've seen seems to imply that's part of 802.2.)
99 #define SSAP_CR_BIT 0x01
102 * Mask to extrace the SAP number from the DSAP or the SSAP.
104 #define SAP_MASK 0xFE
107 * These are for SSAP and DSAP, wth last bit always zero.
108 * XXX - some DSAPs come in separate "individual" and "group" versions,
109 * with the last bit 0 and 1, respectively (e.g., LLC Sub-layer Management,
110 * IBM SNA Path Control, IBM Net Management), but, whilst 0xFE is
111 * the ISO Network Layer Protocol, 0xFF is the Global LSAP.
113 static const value_string sap_vals[] = {
114 { SAP_NULL, "NULL LSAP" },
115 { SAP_LLC_SLMGMT, "LLC Sub-Layer Management" },
116 { SAP_SNA_PATHCTRL, "SNA Path Control" },
117 { SAP_IP, "TCP/IP" },
120 { SAP_PROWAY_NM_INIT, "PROWAY (IEC955) Network Management and Initialization" },
121 { SAP_TI, "Texas Instruments" },
122 { SAP_BPDU, "Spanning Tree BPDU" },
123 { SAP_RS511, "EIA RS-511 Manufacturing Message Service" },
124 { SAP_X25, "ISO 8208 (X.25 over 802.2)" },
126 * XXX - setting the group bit of SAP_X25 make 0x7F; is this just
127 * a group version of that?
129 { 0x7F, "ISO 802.2" },
131 { SAP_NESTAR, "Nestar" },
132 { SAP_PROWAY_ASLM, "PROWAY (IEC955) Active Station List Maintenance" },
133 { SAP_ARP, "ARP" }, /* XXX - hand to "dissect_arp()"? */
134 { SAP_SNAP, "SNAP" },
135 { SAP_VINES1, "Banyan Vines" },
136 { SAP_VINES2, "Banyan Vines" },
137 { SAP_NETWARE, "NetWare" },
138 { SAP_NETBIOS, "NetBIOS" },
139 { SAP_IBMNM, "IBM Net Management" },
140 { SAP_RPL1, "Remote Program Load" },
141 { SAP_UB, "Ungermann-Bass" },
142 { SAP_RPL2, "Remote Program Load" },
143 { SAP_OSINL, "ISO Network Layer" },
144 { SAP_GLOBAL, "Global LSAP" },
148 static struct sap_info saps[] = {
149 { SAP_IP, capture_ip },
150 { SAP_NETWARE, capture_ipx },
151 { SAP_NETBIOS, capture_netbios },
158 * http://www.cisco.com/univercd/cc/td/doc/product/lan/trsrb/vlan.htm
160 * for the PIDs for VTP and DRiP that go with an OUI of OUI_CISCO.
162 const value_string oui_vals[] = {
163 { OUI_ENCAP_ETHER, "Encapsulated Ethernet" },
165 http://www.cisco.com/univercd/cc/td/doc/product/software/ios113ed/113ed_cr/ibm_r/brprt1/brsrb.htm
167 { OUI_CISCO, "Cisco" },
168 { OUI_CISCO_90, "Cisco IOS 9.0 Compatible" },
169 { OUI_BRIDGED, "Frame Relay or ATM bridged frames" },
170 /* RFC 2427, RFC 2684 */
171 { OUI_ATM_FORUM, "ATM Forum" },
172 { OUI_CABLE_BPDU, "DOCSIS Spanning Tree" }, /* DOCSIS spanning tree BPDU */
173 { OUI_APPLE_ATALK, "Apple (AppleTalk)" },
177 static capture_func_t *
178 sap_capture_func(u_char sap) {
181 /* look for the second record where sap == 0, which should
184 while (saps[i].sap > 0 || i == 0) {
185 if (saps[i].sap == sap) {
186 return saps[i].capture_func;
194 capture_llc(const u_char *pd, int offset, int len, packet_counts *ld) {
201 capture_func_t *capture;
203 if (!BYTES_ARE_IN_FRAME(offset, len, 2)) {
207 is_snap = (pd[offset] == SAP_SNAP) && (pd[offset+1] == SAP_SNAP);
208 llc_header_len = 2; /* DSAP + SSAP */
211 * XXX - the page referred to in the comment above about the
212 * Command/Response bit also implies that LLC Type 2 always
213 * uses extended operation, so we don't need to determine
214 * whether it's basic or extended operation; is that the case?
216 control = get_xdlc_control(pd, offset+2, pd[offset+1] & SSAP_CR_BIT,
218 llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
220 llc_header_len += 5; /* 3 bytes of OUI, 2 bytes of protocol ID */
221 if (!BYTES_ARE_IN_FRAME(offset, len, llc_header_len)) {
227 oui = pd[offset+3] << 16 | pd[offset+4] << 8 | pd[offset+5];
228 if (XDLC_IS_INFORMATION(control)) {
229 etype = pntohs(&pd[offset+6]);
232 case OUI_ENCAP_ETHER:
234 case OUI_APPLE_ATALK:
235 /* No, I have no idea why Apple used
236 one of their own OUIs, rather than
237 OUI_ENCAP_ETHER, and an Ethernet
238 packet type as protocol ID, for
239 AppleTalk data packets - but used
240 OUI_ENCAP_ETHER and an Ethernet
241 packet type for AARP packets. */
242 capture_ethertype(etype, pd, offset+8, len,
246 capture_ethertype(etype, pd, offset + 8, len,
256 if (XDLC_IS_INFORMATION(control)) {
257 capture = sap_capture_func(pd[offset]);
260 offset += llc_header_len;
263 capture(pd, offset, len, ld);
273 dissect_llc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
275 proto_tree *llc_tree = NULL;
276 proto_item *ti = NULL;
283 if (check_col(pinfo->cinfo, COL_PROTOCOL)) {
284 col_set_str(pinfo->cinfo, COL_PROTOCOL, "LLC");
286 if (check_col(pinfo->cinfo, COL_INFO)) {
287 col_clear(pinfo->cinfo, COL_INFO);
290 dsap = tvb_get_guint8(tvb, 0);
292 ti = proto_tree_add_item(tree, proto_llc, tvb, 0, 0, FALSE);
293 llc_tree = proto_item_add_subtree(ti, ett_llc);
294 proto_tree_add_uint(llc_tree, hf_llc_dsap, tvb, 0,
296 proto_tree_add_boolean(llc_tree, hf_llc_dsap_ig, tvb, 0,
297 1, dsap & DSAP_GI_BIT);
301 ssap = tvb_get_guint8(tvb, 1);
303 proto_tree_add_uint(llc_tree, hf_llc_ssap, tvb, 1,
305 proto_tree_add_boolean(llc_tree, hf_llc_ssap_cr, tvb, 1,
306 1, ssap & SSAP_CR_BIT);
310 is_snap = (dsap == SAP_SNAP) && (ssap == SAP_SNAP);
311 llc_header_len = 2; /* DSAP + SSAP */
314 * XXX - the page referred to in the comment above about the
315 * Command/Response bit also implies that LLC Type 2 always
316 * uses extended operation, so we don't need to determine
317 * whether it's basic or extended operation; is that the case?
319 control = dissect_xdlc_control(tvb, 2, pinfo, llc_tree,
320 hf_llc_ctrl, ett_llc_ctrl,
321 ssap & SSAP_CR_BIT, TRUE);
322 llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
324 llc_header_len += 5; /* 3 bytes of OUI, 2 bytes of protocol ID */
327 proto_item_set_len(ti, llc_header_len);
330 dissect_snap(tvb, 3, pinfo, tree, llc_tree, control,
331 hf_llc_oui, hf_llc_type, hf_llc_pid, 2);
334 if (check_col(pinfo->cinfo, COL_INFO)) {
335 col_append_fstr(pinfo->cinfo, COL_INFO,
336 "; DSAP %s %s, SSAP %s %s",
337 val_to_str(dsap & SAP_MASK, sap_vals, "%02x"),
339 "Group" : "Individual",
340 val_to_str(ssap & SAP_MASK, sap_vals, "%02x"),
342 "Response" : "Command"
346 next_tvb = tvb_new_subset(tvb, llc_header_len, -1, -1);
347 if (XDLC_IS_INFORMATION(control)) {
349 /* do lookup with the subdissector table */
350 if (!dissector_try_port(subdissector_table, dsap,
351 next_tvb, pinfo, tree)) {
352 call_dissector(data_handle,next_tvb, pinfo, tree);
355 call_dissector(data_handle,next_tvb, pinfo, tree);
361 * Dissect SNAP header; used elsewhere, e.g. in the Frame Relay dissector.
364 dissect_snap(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *tree,
365 proto_tree *snap_tree, int control, int hf_oui, int hf_type, int hf_pid,
372 oui = tvb_get_ntoh24(tvb, offset);
373 etype = tvb_get_ntohs(tvb, offset+3);
375 if (check_col(pinfo->cinfo, COL_INFO)) {
376 col_append_fstr(pinfo->cinfo, COL_INFO,
377 "; SNAP, OUI 0x%06X (%s), PID 0x%04X",
378 oui, val_to_str(oui, oui_vals, "Unknown"), etype);
381 proto_tree_add_uint(snap_tree, hf_oui, tvb, offset, 3, oui);
386 case OUI_ENCAP_ETHER:
388 case OUI_APPLE_ATALK:
389 /* No, I have no idea why Apple used
390 one of their own OUIs, rather than
391 OUI_ENCAP_ETHER, and an Ethernet
392 packet type as protocol ID, for
393 AppleTalk data packets - but used
394 OUI_ENCAP_ETHER and an Ethernet
395 packet type for AARP packets. */
396 if (XDLC_IS_INFORMATION(control)) {
397 ethertype(etype, tvb, offset+5,
398 pinfo, tree, snap_tree, hf_type, -1);
400 next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
401 call_dissector(data_handle,next_tvb, pinfo, tree);
407 * MAC frames bridged over ATM (RFC 2684) or Frame Relay
410 * We have to figure out how much padding to put
411 * into the frame. We were handed a "bridge_pad"
412 * argument which should be 0 for Frame Relay and
413 * 2 for ATM; we add to that the amount of padding
414 * common to both bridging types.
417 proto_tree_add_uint(snap_tree, hf_pid, tvb, offset+3, 2,
423 case BPID_ETH_WITH_FCS:
424 case BPID_ETH_WITHOUT_FCS:
425 next_tvb = tvb_new_subset(tvb, offset+5+bridge_pad,
427 call_dissector(eth_handle, next_tvb, pinfo, tree);
430 case BPID_802_5_WITH_FCS:
431 case BPID_802_5_WITHOUT_FCS:
433 * We treat the last padding byte as the Access
434 * Control byte, as that's what the Token
435 * Ring dissector expects the first byte to
438 next_tvb = tvb_new_subset(tvb, offset+5+bridge_pad,
440 call_dissector(tr_handle, next_tvb, pinfo, tree);
443 case BPID_FDDI_WITH_FCS:
444 case BPID_FDDI_WITHOUT_FCS:
445 next_tvb = tvb_new_subset(tvb, offset+5+1+bridge_pad,
447 call_dissector(fddi_handle, next_tvb, pinfo, tree);
451 next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
452 call_dissector(bpdu_handle, next_tvb, pinfo, tree);
456 next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
457 call_dissector(data_handle,next_tvb, pinfo, tree);
463 /* So are all CDP packets LLC packets
464 with an OUI of OUI_CISCO and a
465 protocol ID of 0x2000, or
466 are some of them raw or encapsulated
469 proto_tree_add_uint(snap_tree, hf_pid, tvb, offset+3, 2,
472 next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
473 if (XDLC_IS_INFORMATION(control)) {
474 /* do lookup with the subdissector table */
475 /* for future reference, 0x0102 is Cisco DRIP */
476 if (!dissector_try_port(cisco_subdissector_table,
477 etype, next_tvb, pinfo, tree))
478 call_dissector(data_handle,next_tvb, pinfo, tree);
480 call_dissector(data_handle,next_tvb, pinfo, tree);
483 case OUI_CABLE_BPDU: /* DOCSIS cable modem spanning tree BPDU */
485 proto_tree_add_uint(snap_tree, hf_pid, tvb, offset+3, 2,
488 next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
489 call_dissector(bpdu_handle, next_tvb, pinfo, tree);
494 proto_tree_add_uint(snap_tree, hf_pid, tvb, offset+3, 2,
497 next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
498 call_dissector(data_handle,next_tvb, pinfo, tree);
504 proto_register_llc(void)
506 static struct true_false_string ig_bit = { "Group", "Individual" };
507 static struct true_false_string cr_bit = { "Response", "Command" };
509 static hf_register_info hf[] = {
511 { "DSAP", "llc.dsap", FT_UINT8, BASE_HEX,
512 VALS(sap_vals), 0x0, "", HFILL }},
515 { "IG Bit", "llc.dsap.ig", FT_BOOLEAN, BASE_HEX,
516 &ig_bit, 0x0, "Individual/Group", HFILL }},
519 { "SSAP", "llc.ssap", FT_UINT8, BASE_HEX,
520 VALS(sap_vals), 0x0, "", HFILL }},
523 { "CR Bit", "llc.ssap.cr", FT_BOOLEAN, BASE_HEX,
524 &cr_bit, 0x0, "Command/Response", HFILL }},
527 { "Control", "llc.control", FT_UINT16, BASE_HEX,
528 NULL, 0x0, "", HFILL }},
530 /* registered here but handled in ethertype.c */
532 { "Type", "llc.type", FT_UINT16, BASE_HEX,
533 VALS(etype_vals), 0x0, "", HFILL }},
536 { "Organization Code", "llc.oui", FT_UINT24, BASE_HEX,
537 VALS(oui_vals), 0x0, "", HFILL }},
540 { "Protocol ID", "llc.pid", FT_UINT16, BASE_HEX,
541 NULL, 0x0, "", HFILL }}
543 static gint *ett[] = {
548 proto_llc = proto_register_protocol("Logical-Link Control", "LLC", "llc");
549 proto_register_field_array(proto_llc, hf, array_length(hf));
550 proto_register_subtree_array(ett, array_length(ett));
552 /* subdissector code */
553 subdissector_table = register_dissector_table("llc.dsap",
554 "LLC SAP", FT_UINT8, BASE_HEX);
555 cisco_subdissector_table = register_dissector_table("llc.cisco_pid",
556 "Cisco OUI PID", FT_UINT16, BASE_HEX);
558 register_dissector("llc", dissect_llc, proto_llc);
562 proto_reg_handoff_llc(void)
564 dissector_handle_t llc_handle;
567 * Get handles for the BPDU, Ethernet, FDDI, and Token Ring
570 bpdu_handle = find_dissector("bpdu");
571 eth_handle = find_dissector("eth");
572 fddi_handle = find_dissector("fddi");
573 tr_handle = find_dissector("tr");
574 data_handle = find_dissector("data");
576 llc_handle = find_dissector("llc");
577 dissector_add("wtap_encap", WTAP_ENCAP_ATM_RFC1483, llc_handle);