2 * Routines for IEEE 802.2 LLC layer
3 * Gilbert Ramirez <gram@xiexie.org>
5 * $Id: packet-llc.c,v 1.77 2001/01/05 19:07:37 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>
41 #include "packet-ip.h"
42 #include "packet-ipx.h"
43 #include "packet-netbios.h"
44 #include "packet-osi.h"
45 #include "packet-sna.h"
47 static int proto_llc = -1;
48 static int hf_llc_dsap = -1;
49 static int hf_llc_ssap = -1;
50 static int hf_llc_dsap_ig = -1;
51 static int hf_llc_ssap_cr = -1;
52 static int hf_llc_ctrl = -1;
53 static int hf_llc_type = -1;
54 static int hf_llc_oui = -1;
55 static int hf_llc_pid = -1;
57 static gint ett_llc = -1;
58 static gint ett_llc_ctrl = -1;
60 static dissector_table_t subdissector_table;
61 static dissector_table_t cisco_subdissector_table;
63 static dissector_handle_t bpdu_handle;
65 typedef void (capture_func_t)(const u_char *, int, packet_counts *);
67 /* The SAP info is split into two tables, one value_string table and one
68 * table of sap_info. This is so that the value_string can be used in the
69 * header field registration.
73 capture_func_t *capture_func;
77 * Group/Individual bit, in the DSAP.
79 #define DSAP_GI_BIT 0x01
82 * Command/Response bit, in the SSAP.
84 * The low-order bit of the SSAP apparently determines whether this
85 * is a request or a response. (RFC 1390, "Transmission of IP and
86 * ARP over FDDI Networks", says
88 * Command frames are identified by having the low order
89 * bit of the SSAP address reset to zero. Response frames
90 * have the low order bit of the SSAP address set to one.
92 * and a page I've seen seems to imply that's part of 802.2.)
94 #define SSAP_CR_BIT 0x01
97 * Mask to extrace the SAP number from the DSAP or the SSAP.
102 * These are for SSAP and DSAP, wth last bit always zero.
103 * XXX - some DSAPs come in separate "individual" and "group" versions,
104 * with the last bit 0 and 1, respectively (e.g., LLC Sub-layer Management,
105 * IBM SNA Path Control, IBM Net Management), but, whilst 0xFE is
106 * the ISO Network Layer Protocol, 0xFF is the Global LSAP.
108 static const value_string sap_vals[] = {
109 { SAP_NULL, "NULL LSAP" },
110 { SAP_LLC_SLMGMT, "LLC Sub-Layer Management" },
111 { SAP_SNA_PATHCTRL, "SNA Path Control" },
112 { SAP_IP, "TCP/IP" },
115 { SAP_PROWAY_NM_INIT, "PROWAY (IEC955) Network Management and Initialization" },
116 { SAP_TI, "Texas Instruments" },
117 { SAP_BPDU, "Spanning Tree BPDU" },
118 { SAP_RS511, "EIA RS-511 Manufacturing Message Service" },
119 { SAP_X25, "ISO 8208 (X.25 over 802.2)" },
121 * XXX - setting the group bit of SAP_X25 make 0x7F; is this just
122 * a group version of that?
124 { 0x7F, "ISO 802.2" },
126 { SAP_NESTAR, "Nestar" },
127 { SAP_PROWAY_ASLM, "PROWAY (IEC955) Active Station List Maintenance" },
128 { SAP_ARP, "ARP" }, /* XXX - hand to "dissect_arp()"? */
129 { SAP_SNAP, "SNAP" },
130 { SAP_VINES1, "Banyan Vines" },
131 { SAP_VINES2, "Banyan Vines" },
132 { SAP_NETWARE, "NetWare" },
133 { SAP_NETBIOS, "NetBIOS" },
134 { SAP_IBMNM, "IBM Net Management" },
135 { SAP_RPL1, "Remote Program Load" },
136 { SAP_UB, "Ungermann-Bass" },
137 { SAP_RPL2, "Remote Program Load" },
138 { SAP_OSINL, "ISO Network Layer" },
139 { SAP_GLOBAL, "Global LSAP" },
143 static struct sap_info saps[] = {
144 { SAP_IP, capture_ip },
145 { SAP_NETWARE, capture_ipx },
146 { SAP_NETBIOS, capture_netbios },
153 * http://www.cisco.com/univercd/cc/td/doc/product/lan/trsrb/vlan.htm
155 * for the PIDs for VTP and DRiP that go with an OUI of OUI_CISCO.
157 const value_string oui_vals[] = {
158 { OUI_ENCAP_ETHER, "Encapsulated Ethernet" },
160 http://www.cisco.com/univercd/cc/td/doc/product/software/ios113ed/113ed_cr/ibm_r/brprt1/brsrb.htm
162 { OUI_CISCO, "Cisco" },
163 { OUI_CISCO_90, "Cisco IOS 9.0 Compatible" },
164 { OUI_BFR, "Bridged Frame-Relay" }, /* RFC 2427 */
165 { OUI_ATM_FORUM, "ATM Forum" },
166 { OUI_APPLE_ATALK, "Apple (AppleTalk)" },
167 { OUI_CABLE_BPDU, "DOCSIS Spanning Tree" }, /* DOCSIS spanning tree BPDU */
171 static capture_func_t *
172 sap_capture_func(u_char sap) {
175 /* look for the second record where sap == 0, which should
178 while (saps[i].sap > 0 || i == 0) {
179 if (saps[i].sap == sap) {
180 return saps[i].capture_func;
188 capture_llc(const u_char *pd, int offset, packet_counts *ld) {
195 capture_func_t *capture;
197 if (!BYTES_ARE_IN_FRAME(offset, 2)) {
201 is_snap = (pd[offset] == SAP_SNAP) && (pd[offset+1] == SAP_SNAP);
202 llc_header_len = 2; /* DSAP + SSAP */
205 * XXX - the page referred to in the comment above about the
206 * Command/Response bit also implies that LLC Type 2 always
207 * uses extended operation, so we don't need to determine
208 * whether it's basic or extended operation; is that the case?
210 control = get_xdlc_control(pd, offset+2, pd[offset+1] & SSAP_CR_BIT,
212 llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
214 llc_header_len += 5; /* 3 bytes of OUI, 2 bytes of protocol ID */
215 if (!BYTES_ARE_IN_FRAME(offset, llc_header_len)) {
221 oui = pd[offset+3] << 16 | pd[offset+4] << 8 | pd[offset+5];
222 if (XDLC_IS_INFORMATION(control)) {
223 etype = pntohs(&pd[offset+6]);
226 case OUI_ENCAP_ETHER:
227 case OUI_APPLE_ATALK:
228 /* No, I have no idea why Apple used
229 one of their own OUIs, rather than
230 OUI_ENCAP_ETHER, and an Ethernet
231 packet type as protocol ID, for
232 AppleTalk data packets - but used
233 OUI_ENCAP_ETHER and an Ethernet
234 packet type for AARP packets. */
235 capture_ethertype(etype, offset+8, pd,
239 capture_ethertype(etype,
249 if (XDLC_IS_INFORMATION(control)) {
250 capture = sap_capture_func(pd[offset]);
253 offset += llc_header_len;
256 capture(pd, offset, ld);
266 dissect_llc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
268 proto_tree *llc_tree = NULL;
269 proto_item *ti = NULL;
280 CHECK_DISPLAY_AS_DATA(proto_llc, tvb, pinfo, tree);
282 pinfo->current_proto = "LLC";
284 if (check_col(pinfo->fd, COL_PROTOCOL)) {
285 col_set_str(pinfo->fd, COL_PROTOCOL, "LLC");
287 if (check_col(pinfo->fd, COL_INFO)) {
288 col_clear(pinfo->fd, COL_INFO);
291 dsap = tvb_get_guint8(tvb, 0);
293 ti = proto_tree_add_item(tree, proto_llc, tvb, 0, 0, FALSE);
294 llc_tree = proto_item_add_subtree(ti, ett_llc);
295 proto_tree_add_uint(llc_tree, hf_llc_dsap, tvb, 0,
297 proto_tree_add_boolean(llc_tree, hf_llc_dsap_ig, tvb, 0,
298 1, dsap & DSAP_GI_BIT);
302 ssap = tvb_get_guint8(tvb, 1);
304 proto_tree_add_uint(llc_tree, hf_llc_ssap, tvb, 1,
306 proto_tree_add_boolean(llc_tree, hf_llc_ssap_cr, tvb, 1,
307 1, ssap & SSAP_CR_BIT);
311 is_snap = (dsap == SAP_SNAP) && (ssap == SAP_SNAP);
312 llc_header_len = 2; /* DSAP + SSAP */
315 * XXX - the page referred to in the comment above about the
316 * Command/Response bit also implies that LLC Type 2 always
317 * uses extended operation, so we don't need to determine
318 * whether it's basic or extended operation; is that the case?
320 control = dissect_xdlc_control(tvb, 2, pinfo, llc_tree,
321 hf_llc_ctrl, ett_llc_ctrl,
322 ssap & SSAP_CR_BIT, TRUE);
323 llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
325 llc_header_len += 5; /* 3 bytes of OUI, 2 bytes of protocol ID */
328 proto_item_set_len(ti, llc_header_len);
331 oui = tvb_get_ntoh24(tvb, 3);
332 etype = tvb_get_ntohs(tvb, 6);
334 if (check_col(pinfo->fd, COL_INFO)) {
335 col_append_fstr(pinfo->fd, COL_INFO, "; SNAP, OUI 0x%06X (%s), PID 0x%04X",
336 oui, val_to_str(oui, oui_vals, "Unknown"),
340 proto_tree_add_uint(llc_tree, hf_llc_oui, tvb, 3, 3,
344 next_tvb = tvb_new_subset(tvb, 8, -1, -1);
345 tvb_compat(next_tvb, &pd, &offset);
349 case OUI_ENCAP_ETHER:
350 case OUI_APPLE_ATALK:
351 /* No, I have no idea why Apple used
352 one of their own OUIs, rather than
353 OUI_ENCAP_ETHER, and an Ethernet
354 packet type as protocol ID, for
355 AppleTalk data packets - but used
356 OUI_ENCAP_ETHER and an Ethernet
357 packet type for AARP packets. */
358 if (XDLC_IS_INFORMATION(control)) {
359 ethertype(etype, tvb, 8,
360 pinfo, tree, llc_tree, hf_llc_type);
362 dissect_data(next_tvb, 0, pinfo, tree);
366 /* So are all CDP packets LLC packets
367 with an OUI of OUI_CISCO and a
368 protocol ID of 0x2000, or
369 are some of them raw or encapsulated
372 proto_tree_add_uint(llc_tree,
373 hf_llc_pid, tvb, 6, 2, etype);
375 if (XDLC_IS_INFORMATION(control)) {
376 /* do lookup with the subdissector table */
377 /* for future reference, 0x0102 is Cisco DRIP */
378 if (!dissector_try_port(cisco_subdissector_table,
379 etype, next_tvb, pinfo, tree))
380 dissect_data(next_tvb, 0, pinfo, tree);
382 dissect_data(next_tvb, 0, pinfo, tree);
385 case OUI_CABLE_BPDU: /* DOCSIS cable modem spanning tree BPDU */
387 proto_tree_add_uint(llc_tree,
388 hf_llc_pid, tvb, 6, 2, etype);
390 call_dissector(bpdu_handle, next_tvb, pinfo, tree);
395 proto_tree_add_uint(llc_tree,
396 hf_llc_pid, tvb, 6, 2, etype);
398 dissect_data(next_tvb, 0, pinfo, tree);
403 if (check_col(pinfo->fd, COL_INFO)) {
404 col_append_fstr(pinfo->fd, COL_INFO,
405 "; DSAP %s %s, SSAP %s %s",
406 val_to_str(dsap & SAP_MASK, sap_vals, "%02x"),
408 "Group" : "Individual",
409 val_to_str(ssap & SAP_MASK, sap_vals, "%02x"),
411 "Response" : "Command"
415 next_tvb = tvb_new_subset(tvb, llc_header_len, -1, -1);
416 if (XDLC_IS_INFORMATION(control)) {
418 /* do lookup with the subdissector table */
419 if (!dissector_try_port(subdissector_table, dsap,
420 next_tvb, pinfo, tree)) {
421 dissect_data(next_tvb, 0, pinfo, tree);
424 dissect_data(next_tvb, 0, pinfo, tree);
430 proto_register_llc(void)
432 static struct true_false_string ig_bit = { "Group", "Individual" };
433 static struct true_false_string cr_bit = { "Response", "Command" };
435 static hf_register_info hf[] = {
437 { "DSAP", "llc.dsap", FT_UINT8, BASE_HEX,
438 VALS(sap_vals), 0x0, "" }},
441 { "IG Bit", "llc.dsap.ig", FT_BOOLEAN, BASE_HEX,
442 &ig_bit, 0x0, "Individual/Group" }},
445 { "SSAP", "llc.ssap", FT_UINT8, BASE_HEX,
446 VALS(sap_vals), 0x0, "" }},
449 { "CR Bit", "llc.ssap.cr", FT_BOOLEAN, BASE_HEX,
450 &cr_bit, 0x0, "Command/Response" }},
453 { "Control", "llc.control", FT_UINT16, BASE_HEX,
456 /* registered here but handled in ethertype.c */
458 { "Type", "llc.type", FT_UINT16, BASE_HEX,
459 VALS(etype_vals), 0x0, "" }},
462 { "Organization Code", "llc.oui", FT_UINT24, BASE_HEX,
463 VALS(oui_vals), 0x0, ""}},
466 { "Protocol ID", "llc.pid", FT_UINT16, BASE_HEX,
469 static gint *ett[] = {
474 proto_llc = proto_register_protocol("Logical-Link Control", "LLC", "llc");
475 proto_register_field_array(proto_llc, hf, array_length(hf));
476 proto_register_subtree_array(ett, array_length(ett));
478 /* subdissector code */
479 subdissector_table = register_dissector_table("llc.dsap");
480 cisco_subdissector_table = register_dissector_table("llc.cisco_pid");
482 register_dissector("llc", dissect_llc);
486 proto_reg_handoff_llc(void)
489 * Get a handle for the BPDU dissector.
491 bpdu_handle = find_dissector("bpdu");
493 dissector_add("wtap_encap", WTAP_ENCAP_ATM_RFC1483, dissect_llc);