packet-llc.c

   1 /* packet-llc.c
   2  * Routines for IEEE 802.2 LLC layer
   3  * Gilbert Ramirez <gram@alumni.rice.edu>
   4  *
   5  * $Id: packet-llc.c,v 1.112 2003/08/28 01:29:15 guy Exp $
   6  *
   7  * Ethereal - Network traffic analyzer
   8  * By Gerald Combs <gerald@ethereal.com>
   9  * Copyright 1998 Gerald Combs
  10  *
  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.
  15  *
  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.
  20  *
  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.
  24  */
  25
  26 #ifdef HAVE_CONFIG_H
  27 # include "config.h"
  28 #endif
  29
  30 #include <glib.h>
  31 #include <epan/packet.h>
  32 #include "oui.h"
  33 #include "xdlc.h"
  34 #include "etypes.h"
  35 #include "llcsaps.h"
  36 #include "bridged_pids.h"
  37 #include "ppptypes.h"
  38 #include "arcnet_pids.h"
  39 #include "packet-fc.h"
  40 #include "packet-ip.h"
  41 #include "packet-ipx.h"
  42 #include "packet-netbios.h"
  43 #include "packet-vines.h"
  44 #include <epan/sna-utils.h>
  45
  46 #include "packet-llc.h"
  47
  48 #define UDP_PORT_LLC1   12000
  49 #define UDP_PORT_LLC2   12001
  50 #define UDP_PORT_LLC3   12002
  51 #define UDP_PORT_LLC4   12003
  52 #define UDP_PORT_LLC5   12004
  53
  54 static int proto_llc = -1;
  55 static int hf_llc_dsap = -1;
  56 static int hf_llc_ssap = -1;
  57 static int hf_llc_dsap_ig = -1;
  58 static int hf_llc_ssap_cr = -1;
  59 static int hf_llc_ctrl = -1;
  60 static int hf_llc_type = -1;
  61 static int hf_llc_oui = -1;
  62 static int hf_llc_pid = -1;
  63
  64 static gint ett_llc = -1;
  65 static gint ett_llc_ctrl = -1;
  66
  67 static dissector_table_t subdissector_table;
  68 static dissector_table_t cisco_subdissector_table;
  69 static dissector_table_t xid_subdissector_table;
  70
  71 static dissector_table_t nortel_subdissector_table;
  72
  73 static dissector_handle_t bpdu_handle;
  74 static dissector_handle_t eth_handle;
  75 static dissector_handle_t fddi_handle;
  76 static dissector_handle_t tr_handle;
  77 static dissector_handle_t data_handle;
  78
  79 /*
  80  * Group/Individual bit, in the DSAP.
  81  */
  82 #define DSAP_GI_BIT     0x01
  83
  84 /*
  85  * Command/Response bit, in the SSAP.
  86  *
  87  * The low-order bit of the SSAP apparently determines whether this
  88  * is a request or a response.  (RFC 1390, "Transmission of IP and
  89  * ARP over FDDI Networks", says
  90  *
  91  *      Command frames are identified by having the low order
  92  *      bit of the SSAP address reset to zero.  Response frames
  93  *      have the low order bit of the SSAP address set to one.
  94  *
  95  * and a page I've seen seems to imply that's part of 802.2.)
  96  */
  97 #define SSAP_CR_BIT     0x01
  98
  99 /*
 100  * Mask to extrace the SAP number from the DSAP or the SSAP.
 101  */
 102 #define SAP_MASK        0xFE
 103
 104 /*
 105  * These are for SSAP and DSAP, wth last bit always zero.
 106  * XXX - some DSAPs come in separate "individual" and "group" versions,
 107  * with the last bit 0 and 1, respectively (e.g., LLC Sub-layer Management,
 108  * IBM SNA Path Control, IBM Net Management), but, whilst 0xFE is
 109  * the ISO Network Layer Protocol, 0xFF is the Global LSAP.
 110  */
 111 const value_string sap_vals[] = {
 112         { SAP_NULL,           "NULL LSAP" },
 113         { SAP_LLC_SLMGMT,     "LLC Sub-Layer Management" },
 114         { SAP_SNA_PATHCTRL,   "SNA Path Control" },
 115         { SAP_IP,             "TCP/IP" },
 116         { SAP_SNA1,           "SNA" },
 117         { SAP_SNA2,           "SNA" },
 118         { SAP_PROWAY_NM_INIT, "PROWAY (IEC955) Network Management and Initialization" },
 119         { SAP_NETWARE1,       "NetWare (unofficial?)" },
 120         { SAP_OSINL1,         "ISO Network Layer (OSLAN 1)" },
 121         { SAP_TI,             "Texas Instruments" },
 122         { SAP_OSINL2,         "ISO Network Layer (unofficial?)" },
 123         { SAP_OSINL3,         "ISO Network Layer (unofficial?)" },
 124         { SAP_BPDU,           "Spanning Tree BPDU" },
 125         { SAP_RS511,          "EIA RS-511 Manufacturing Message Service" },
 126         { SAP_OSINL4,         "ISO Network Layer (OSLAN 2)" },
 127         { SAP_X25,            "ISO 8208 (X.25 over 802.2)" },
 128         /*
 129          * XXX - setting the group bit of SAP_X25 make 0x7F; is this just
 130          * a group version of that?
 131          */
 132         { 0x7F,               "ISO 802.2" },
 133         { SAP_XNS,            "XNS" },
 134         { SAP_BACNET,         "BACnet" },
 135         { SAP_NESTAR,         "Nestar" },
 136         { SAP_PROWAY_ASLM,    "PROWAY (IEC955) Active Station List Maintenance" },
 137         { SAP_ARP,            "ARP" },  /* XXX - hand to "dissect_arp()"? */
 138         { SAP_SNAP,           "SNAP" },
 139         { SAP_VINES1,         "Banyan Vines" },
 140         { SAP_VINES2,         "Banyan Vines" },
 141         { SAP_NETWARE2,       "NetWare" },
 142         { SAP_NETBIOS,        "NetBIOS" },
 143         { SAP_IBMNM,          "IBM Net Management" },
 144         { SAP_HPEXT,          "HP Extended LLC" },
 145         { SAP_UB,             "Ungermann-Bass" },
 146         { SAP_RPL,            "Remote Program Load" },
 147         { SAP_OSINL5,         "ISO Network Layer" },
 148         { SAP_GLOBAL,         "Global LSAP" },
 149         { 0x00,               NULL }
 150 };
 151
 152 /*
 153  * See
 154  *
 155  * http://www.cisco.com/univercd/cc/td/doc/product/lan/trsrb/vlan.htm
 156  *
 157  * for the PIDs for VTP and DRiP that go with an OUI of OUI_CISCO.
 158  */
 159 const value_string oui_vals[] = {
 160         { OUI_ENCAP_ETHER, "Encapsulated Ethernet" },
 161 /*
 162 http://www.cisco.com/univercd/cc/td/doc/product/software/ios113ed/113ed_cr/ibm_r/brprt1/brsrb.htm
 163 */
 164         { OUI_CISCO,       "Cisco" },
 165         { OUI_CISCO_90,    "Cisco IOS 9.0 Compatible" },
 166         { OUI_BRIDGED,     "Frame Relay or ATM bridged frames" },
 167                                 /* RFC 2427, RFC 2684 */
 168         { OUI_ATM_FORUM,   "ATM Forum" },
 169         { OUI_CABLE_BPDU,  "DOCSIS Spanning Tree" }, /* DOCSIS spanning tree BPDU */
 170         { OUI_APPLE_ATALK, "Apple (AppleTalk)" },
 171         { OUI_NORTEL,   "Nortel Networks SONMP" },
 172         { 0,               NULL }
 173 };
 174
 175 /*
 176  * Hash table for translating OUIs to a dissector table/field ID pair;
 177  * the dissector table maps PID values to dissectors, and the field
 178  * corresponds to the PID for that OUI.
 179  */
 180 typedef struct {
 181         dissector_table_t table;
 182         int     field_id;
 183 } oui_info_t;
 184
 185 static GHashTable *oui_dissector_tables = NULL;
 186
 187 /*
 188  * Add an entry for a new OID.
 189  */
 190 void
 191 llc_add_oid(guint32 oid, const char *table_name, char *table_ui_name,
 192     int field_id)
 193 {
 194         oui_info_t *new_info;
 195
 196         new_info = g_malloc(sizeof (oui_info_t));
 197         new_info->table = register_dissector_table(table_name,
 198             table_ui_name, FT_UINT16, BASE_HEX);
 199         new_info->field_id = field_id;
 200
 201         /*
 202          * Create the hash table for OUI information, if it doesn't
 203          * already exist.
 204          */
 205         if (oui_dissector_tables == NULL) {
 206                 oui_dissector_tables = g_hash_table_new(g_direct_hash,
 207                     g_direct_equal);
 208         }
 209         g_hash_table_insert(oui_dissector_tables, (gpointer)oid,
 210             new_info->table);
 211 }
 212
 213 void
 214 capture_llc(const guchar *pd, int offset, int len, packet_counts *ld) {
 215
 216         int             is_snap;
 217         guint16         control;
 218         int             llc_header_len;
 219         guint32         oui;
 220         guint16         etype;
 221
 222         if (!BYTES_ARE_IN_FRAME(offset, len, 2)) {
 223                 ld->other++;
 224                 return;
 225         }
 226         is_snap = (pd[offset] == SAP_SNAP) && (pd[offset+1] == SAP_SNAP);
 227         llc_header_len = 2;     /* DSAP + SSAP */
 228
 229         /*
 230          * XXX - the page referred to in the comment above about the
 231          * Command/Response bit also implies that LLC Type 2 always
 232          * uses extended operation, so we don't need to determine
 233          * whether it's basic or extended operation; is that the case?
 234          */
 235         control = get_xdlc_control(pd, offset+2, pd[offset+1] & SSAP_CR_BIT);
 236         llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
 237         if (is_snap)
 238                 llc_header_len += 5;    /* 3 bytes of OUI, 2 bytes of protocol ID */
 239         if (!BYTES_ARE_IN_FRAME(offset, len, llc_header_len)) {
 240                 ld->other++;
 241                 return;
 242         }
 243
 244         if (is_snap) {
 245                 oui = pd[offset+3] << 16 | pd[offset+4] << 8 | pd[offset+5];
 246                 if (XDLC_IS_INFORMATION(control)) {
 247                         etype = pntohs(&pd[offset+6]);
 248                         switch (oui) {
 249
 250                         case OUI_ENCAP_ETHER:
 251                         case OUI_CISCO_90:
 252                         case OUI_APPLE_ATALK:
 253                                 /* No, I have no idea why Apple used
 254                                    one of their own OUIs, rather than
 255                                    OUI_ENCAP_ETHER, and an Ethernet
 256                                    packet type as protocol ID, for
 257                                    AppleTalk data packets - but used
 258                                    OUI_ENCAP_ETHER and an Ethernet
 259                                    packet type for AARP packets. */
 260                                 capture_ethertype(etype, pd, offset+8, len,
 261                                     ld);
 262                                 break;
 263                         case OUI_CISCO:
 264                                 capture_ethertype(etype, pd, offset + 8, len,
 265                                     ld);
 266                                 break;
 267                         default:
 268                                 ld->other++;
 269                                 break;
 270                         }
 271                 }
 272         }
 273         else {
 274                 /* non-SNAP */
 275                 if (XDLC_IS_INFORMATION(control)) {
 276                         switch (pd[offset]) {
 277
 278                         case SAP_IP:
 279                                 capture_ip(pd, offset + llc_header_len, len,
 280                                     ld);
 281                                 break;
 282
 283                         case SAP_NETWARE1:
 284                         case SAP_NETWARE2:
 285                                 capture_ipx(ld);
 286                                 break;
 287
 288                         case SAP_NETBIOS:
 289                                 capture_netbios(ld);
 290                                 break;
 291
 292                         case SAP_VINES1:
 293                         case SAP_VINES2:
 294                                 capture_vines(ld);
 295                                 break;
 296
 297                         default:
 298                                 ld->other++;
 299                                 break;
 300                         }
 301                 }
 302         }
 303 }
 304
 305 static void
 306 dissect_llc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 307 {
 308         proto_tree      *llc_tree = NULL;
 309         proto_item      *ti = NULL;
 310         int             is_snap;
 311         guint16         control;
 312         int             llc_header_len;
 313         guint8          dsap, ssap;
 314         tvbuff_t        *next_tvb;
 315
 316         if (check_col(pinfo->cinfo, COL_PROTOCOL)) {
 317                 col_set_str(pinfo->cinfo, COL_PROTOCOL, "LLC");
 318         }
 319         if (check_col(pinfo->cinfo, COL_INFO)) {
 320                 col_clear(pinfo->cinfo, COL_INFO);
 321         }
 322
 323         dsap = tvb_get_guint8(tvb, 0);
 324         if (tree) {
 325                 ti = proto_tree_add_item(tree, proto_llc, tvb, 0, -1, FALSE);
 326                 llc_tree = proto_item_add_subtree(ti, ett_llc);
 327                 proto_tree_add_uint(llc_tree, hf_llc_dsap, tvb, 0,
 328                         1, dsap & SAP_MASK);
 329                 proto_tree_add_boolean(llc_tree, hf_llc_dsap_ig, tvb, 0,
 330                         1, dsap & DSAP_GI_BIT);
 331         } else
 332                 llc_tree = NULL;
 333
 334         ssap = tvb_get_guint8(tvb, 1);
 335         if (tree) {
 336                 proto_tree_add_uint(llc_tree, hf_llc_ssap, tvb, 1,
 337                         1, ssap & SAP_MASK);
 338                 proto_tree_add_boolean(llc_tree, hf_llc_ssap_cr, tvb, 1,
 339                         1, ssap & SSAP_CR_BIT);
 340         } else
 341                 llc_tree = NULL;
 342
 343         is_snap = (dsap == SAP_SNAP) && (ssap == SAP_SNAP);
 344         llc_header_len = 2;     /* DSAP + SSAP */
 345
 346         /*
 347          * XXX - the page referred to in the comment above about the
 348          * Command/Response bit also implies that LLC Type 2 always
 349          * uses extended operation, so we don't need to determine
 350          * whether it's basic or extended operation; is that the case?
 351          */
 352         control = dissect_xdlc_control(tvb, 2, pinfo, llc_tree,
 353                                 hf_llc_ctrl, ett_llc_ctrl,
 354                                 ssap & SSAP_CR_BIT, TRUE);
 355         llc_header_len += XDLC_CONTROL_LEN(control, TRUE);
 356         if (is_snap)
 357                 llc_header_len += 5;    /* 3 bytes of OUI, 2 bytes of protocol ID */
 358
 359         if (tree)
 360                 proto_item_set_len(ti, llc_header_len);
 361
 362         if (is_snap) {
 363                 dissect_snap(tvb, 3, pinfo, tree, llc_tree, control,
 364                     hf_llc_oui, hf_llc_type, hf_llc_pid, 2);
 365         }
 366         else {
 367                 if (check_col(pinfo->cinfo, COL_INFO)) {
 368                         col_append_fstr(pinfo->cinfo, COL_INFO,
 369                             "; DSAP %s %s, SSAP %s %s",
 370                             val_to_str(dsap & SAP_MASK, sap_vals, "%02x"),
 371                             dsap & DSAP_GI_BIT ?
 372                               "Group" : "Individual",
 373                             val_to_str(ssap & SAP_MASK, sap_vals, "%02x"),
 374                             ssap & SSAP_CR_BIT ?
 375                               "Response" : "Command"
 376                         );
 377                 }
 378
 379                 if (tvb_length_remaining(tvb, llc_header_len) > 0) {
 380                         next_tvb = tvb_new_subset(tvb, llc_header_len, -1, -1);
 381                         if (XDLC_IS_INFORMATION(control)) {
 382                                 /*
 383                                  * Non-SNAP I or UI frame.
 384                                  * Try the regular LLC subdissector table
 385                                  * with the DSAP.
 386                                  */
 387                                 if (!dissector_try_port(subdissector_table,
 388                                     dsap, next_tvb, pinfo, tree)) {
 389                                         call_dissector(data_handle, next_tvb,
 390                                             pinfo, tree);
 391                                 }
 392                         } else if ((control & (XDLC_U_MODIFIER_MASK|XDLC_U))
 393                             == (XDLC_XID|XDLC_U)) {
 394                                 /*
 395                                  * Non-SNAP XID frame.
 396                                  * Try the XID LLC subdissector table
 397                                  * with the DSAP.
 398                                  */
 399                                 if (!dissector_try_port(xid_subdissector_table,
 400                                     dsap, next_tvb, pinfo, tree)) {
 401                                         call_dissector(data_handle, next_tvb,
 402                                             pinfo, tree);
 403                                 }
 404                         } else {
 405                                 call_dissector(data_handle, next_tvb, pinfo,
 406                                     tree);
 407                         }
 408                 }
 409         }
 410 }
 411
 412 /*
 413  * Dissect SNAP header; used elsewhere, e.g. in the Frame Relay dissector.
 414  */
 415 void
 416 dissect_snap(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *tree,
 417     proto_tree *snap_tree, int control, int hf_oui, int hf_type, int hf_pid,
 418     int bridge_pad)
 419 {
 420         guint32         oui;
 421         guint16         etype;
 422         tvbuff_t        *next_tvb;
 423         oui_info_t      *oui_info;
 424         dissector_table_t subdissector_table;
 425         int             hf;
 426
 427         oui =   tvb_get_ntoh24(tvb, offset);
 428         etype = tvb_get_ntohs(tvb, offset+3);
 429
 430         if (check_col(pinfo->cinfo, COL_INFO)) {
 431                 col_append_fstr(pinfo->cinfo, COL_INFO,
 432                     "; SNAP, OUI 0x%06X (%s), PID 0x%04X",
 433                     oui, val_to_str(oui, oui_vals, "Unknown"), etype);
 434         }
 435         if (tree) {
 436                 proto_tree_add_uint(snap_tree, hf_oui, tvb, offset, 3, oui);
 437         }
 438
 439         switch (oui) {
 440
 441         case OUI_ENCAP_ETHER:
 442         case OUI_CISCO_90:
 443         case OUI_APPLE_ATALK:
 444                 /* No, I have no idea why Apple used
 445                    one of their own OUIs, rather than
 446                    OUI_ENCAP_ETHER, and an Ethernet
 447                    packet type as protocol ID, for
 448                    AppleTalk data packets - but used
 449                    OUI_ENCAP_ETHER and an Ethernet
 450                    packet type for AARP packets. */
 451                 if (XDLC_IS_INFORMATION(control)) {
 452                         ethertype(etype, tvb, offset+5,
 453                             pinfo, tree, snap_tree, hf_type, -1);
 454                 } else {
 455                         next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 456                         call_dissector(data_handle,next_tvb, pinfo, tree);
 457                 }
 458                 break;
 459
 460         case OUI_BRIDGED:
 461                 /*
 462                  * MAC frames bridged over ATM (RFC 2684) or Frame Relay
 463                  * (RFC 2427).
 464                  *
 465                  * We have to figure out how much padding to put
 466                  * into the frame.  We were handed a "bridge_pad"
 467                  * argument which should be 0 for Frame Relay and
 468                  * 2 for ATM; we add to that the amount of padding
 469                  * common to both bridging types.
 470                  */
 471                 if (tree) {
 472                         proto_tree_add_uint(snap_tree, hf_pid, tvb, offset+3, 2,
 473                             etype);
 474                 }
 475
 476                 switch (etype) {
 477
 478                 case BPID_ETH_WITH_FCS:
 479                 case BPID_ETH_WITHOUT_FCS:
 480                         next_tvb = tvb_new_subset(tvb, offset+5+bridge_pad,
 481                             -1, -1);
 482                         call_dissector(eth_handle, next_tvb, pinfo, tree);
 483                         break;
 484
 485                 case BPID_802_5_WITH_FCS:
 486                 case BPID_802_5_WITHOUT_FCS:
 487                         /*
 488                          * We treat the last padding byte as the Access
 489                          * Control byte, as that's what the Token
 490                          * Ring dissector expects the first byte to
 491                          * be.
 492                          */
 493                         next_tvb = tvb_new_subset(tvb, offset+5+bridge_pad,
 494                             -1, -1);
 495                         call_dissector(tr_handle, next_tvb, pinfo, tree);
 496                         break;
 497
 498                 case BPID_FDDI_WITH_FCS:
 499                 case BPID_FDDI_WITHOUT_FCS:
 500                         next_tvb = tvb_new_subset(tvb, offset+5+1+bridge_pad,
 501                             -1, -1);
 502                         call_dissector(fddi_handle, next_tvb, pinfo, tree);
 503                         break;
 504
 505                 case BPID_BPDU:
 506                         next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 507                         call_dissector(bpdu_handle, next_tvb, pinfo, tree);
 508                         break;
 509
 510                 default:
 511                         next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 512                         call_dissector(data_handle,next_tvb, pinfo, tree);
 513                         break;
 514                 }
 515                 break;
 516
 517         case OUI_CISCO:
 518                 /* So are all CDP packets LLC packets
 519                    with an OUI of OUI_CISCO and a
 520                    protocol ID of 0x2000, or
 521                    are some of them raw or encapsulated
 522                    Ethernet? */
 523                 if (tree) {
 524                         proto_tree_add_uint(snap_tree, hf_pid, tvb, offset+3, 2,
 525                             etype);
 526                 }
 527                 next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 528                 if (XDLC_IS_INFORMATION(control)) {
 529                         /* do lookup with the subdissector table */
 530                         /* for future reference, 0x0102 is Cisco DRIP */
 531                         if (!dissector_try_port(cisco_subdissector_table,
 532                             etype, next_tvb, pinfo, tree))
 533                                 call_dissector(data_handle,next_tvb, pinfo, tree);
 534                 } else
 535                         call_dissector(data_handle,next_tvb, pinfo, tree);
 536                 break;
 537
 538         case OUI_CABLE_BPDU:    /* DOCSIS cable modem spanning tree BPDU */
 539                 if (tree) {
 540                         proto_tree_add_uint(snap_tree, hf_pid, tvb, offset+3, 2,
 541                             etype);
 542                 }
 543                 next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 544                 call_dissector(bpdu_handle, next_tvb, pinfo, tree);
 545                 break;
 546
 547         case OUI_NORTEL:
 548                 /* Nortel Networks
 549                  * Synoptics Networks Management Protocol
 550                  * protocol ID's 0x01a1, 0x01a2, 0x01a3
 551                  */
 552                 if (tree) {
 553                         proto_tree_add_uint(snap_tree, hf_pid,tvb, offset+3,2, etype);
 554                 }
 555                 next_tvb = tvb_new_subset(tvb, offset + 5, -1, -1);
 556                 if (XDLC_IS_INFORMATION(control)) {
 557                         /* do lookup with the subdissector table */
 558                         if (!dissector_try_port(nortel_subdissector_table,
 559                                 etype, next_tvb, pinfo, tree))
 560                                         call_dissector(data_handle, next_tvb, pinfo, tree);
 561                 } else
 562                         call_dissector(data_handle, next_tvb, pinfo, tree);
 563                 break;
 564
 565         default:
 566                 /*
 567                  * Do we have information for this OUI?
 568                  */
 569                 oui_info = g_hash_table_lookup(oui_dissector_tables,
 570                     (gpointer)oui);
 571                 if (oui_info != NULL) {
 572                         /*
 573                          * Yes - use it.
 574                          */
 575                         hf = oui_info->field_id;
 576                         subdissector_table = oui_info->table;
 577                 } else {
 578                         /*
 579                          * No, use hf_pid for the PID and just dissect
 580                          * the payload as data.
 581                          */
 582                         hf = hf_pid;
 583                         subdissector_table = NULL;
 584                 }
 585                 if (tree) {
 586                         proto_tree_add_uint(snap_tree, hf, tvb, offset+3, 2,
 587                             etype);
 588                 }
 589                 next_tvb = tvb_new_subset(tvb, offset+5, -1, -1);
 590                 if (XDLC_IS_INFORMATION(control)) {
 591                         if (subdissector_table != NULL) {
 592                                 /* do lookup with the subdissector table */
 593                                 if (dissector_try_port(subdissector_table,
 594                                     etype, next_tvb, pinfo, tree))
 595                                         break;
 596                         }
 597                 }
 598                 call_dissector(data_handle, next_tvb, pinfo, tree);
 599                 break;
 600         }
 601 }
 602
 603 void
 604 proto_register_llc(void)
 605 {
 606         static struct true_false_string ig_bit = { "Group", "Individual" };
 607         static struct true_false_string cr_bit = { "Response", "Command" };
 608
 609         static hf_register_info hf[] = {
 610                 { &hf_llc_dsap,
 611                 { "DSAP",       "llc.dsap", FT_UINT8, BASE_HEX,
 612                         VALS(sap_vals), 0x0, "", HFILL }},
 613
 614                 { &hf_llc_dsap_ig,
 615                 { "IG Bit",     "llc.dsap.ig", FT_BOOLEAN, BASE_HEX,
 616                         &ig_bit, 0x0, "Individual/Group", HFILL }},
 617
 618                 { &hf_llc_ssap,
 619                 { "SSAP", "llc.ssap", FT_UINT8, BASE_HEX,
 620                         VALS(sap_vals), 0x0, "", HFILL }},
 621
 622                 { &hf_llc_ssap_cr,
 623                 { "CR Bit", "llc.ssap.cr", FT_BOOLEAN, BASE_HEX,
 624                         &cr_bit, 0x0, "Command/Response", HFILL }},
 625
 626                 { &hf_llc_ctrl,
 627                 { "Control", "llc.control", FT_UINT16, BASE_HEX,
 628                         NULL, 0x0, "", HFILL }},
 629
 630                 /* registered here but handled in ethertype.c */
 631                 { &hf_llc_type,
 632                 { "Type", "llc.type", FT_UINT16, BASE_HEX,
 633                         VALS(etype_vals), 0x0, "", HFILL }},
 634
 635                 { &hf_llc_oui,
 636                 { "Organization Code",  "llc.oui", FT_UINT24, BASE_HEX,
 637                         VALS(oui_vals), 0x0, "", HFILL }},
 638
 639                 { &hf_llc_pid,
 640                 { "Protocol ID", "llc.pid", FT_UINT16, BASE_HEX,
 641                         NULL, 0x0, "", HFILL }}
 642         };
 643         static gint *ett[] = {
 644                 &ett_llc,
 645                 &ett_llc_ctrl,
 646         };
 647
 648         proto_llc = proto_register_protocol("Logical-Link Control", "LLC", "llc");
 649         proto_register_field_array(proto_llc, hf, array_length(hf));
 650         proto_register_subtree_array(ett, array_length(ett));
 651
 652 /* subdissector code */
 653         subdissector_table = register_dissector_table("llc.dsap",
 654           "LLC SAP", FT_UINT8, BASE_HEX);
 655         cisco_subdissector_table = register_dissector_table("llc.cisco_pid",
 656           "Cisco OUI PID", FT_UINT16, BASE_HEX);
 657         xid_subdissector_table = register_dissector_table("llc.xid_dsap",
 658           "LLC XID SAP", FT_UINT8, BASE_HEX);
 659         nortel_subdissector_table = register_dissector_table("llc.nortel_pid",
 660           "Nortel OUI PID", FT_UINT16, BASE_HEX);
 661
 662         register_dissector("llc", dissect_llc, proto_llc);
 663 }
 664
 665 void
 666 proto_reg_handoff_llc(void)
 667 {
 668         dissector_handle_t llc_handle;
 669
 670         /*
 671          * Get handles for the BPDU, Ethernet, FDDI, and Token Ring
 672          * dissectors.
 673          */
 674         bpdu_handle = find_dissector("bpdu");
 675         eth_handle = find_dissector("eth");
 676         fddi_handle = find_dissector("fddi");
 677         tr_handle = find_dissector("tr");
 678         data_handle = find_dissector("data");
 679
 680         llc_handle = find_dissector("llc");
 681         dissector_add("wtap_encap", WTAP_ENCAP_ATM_RFC1483, llc_handle);
 682         /* RFC 2043 */
 683         dissector_add("ppp.protocol", PPP_LLC, llc_handle);
 684         /* RFC 2353 */
 685         dissector_add("udp.port", UDP_PORT_LLC1, llc_handle);
 686         dissector_add("udp.port", UDP_PORT_LLC2, llc_handle);
 687         dissector_add("udp.port", UDP_PORT_LLC3, llc_handle);
 688         dissector_add("udp.port", UDP_PORT_LLC4, llc_handle);
 689         dissector_add("udp.port", UDP_PORT_LLC5, llc_handle);
 690         /* IP-over-FC when we have the full FC frame */
 691         dissector_add("fc.ftype", FC_FTYPE_IP, llc_handle);
 692
 693         /*
 694          * BACNET-over-ARCNET is really BACNET-over-802.2 LLC-over-ARCNET,
 695          * apparently.
 696          */
 697         dissector_add("arcnet.protocol_id", ARCNET_PROTO_BACNET, llc_handle);
 698 }