packet-bpdu.c

   1 /* packet-bpdu.c
   2  * Routines for BPDU (Spanning Tree Protocol) disassembly
   3  *
   4  * $Id: packet-bpdu.c,v 1.37 2002/08/02 23:35:47 jmayer Exp $
   5  *
   6  * Copyright 1999 Christophe Tronche <ch.tronche@computer.org>
   7  *
   8  * Ethereal - Network traffic analyzer
   9  * By Gerald Combs <gerald@ethereal.com>
  10  * Copyright 1998 Gerald Combs
  11  *
  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.
  16  *
  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.
  21  *
  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.
  25  */
  26
  27 #ifdef HAVE_CONFIG_H
  28 # include "config.h"
  29 #endif
  30
  31 #include <stdio.h>
  32 #include <string.h>
  33 #include <glib.h>
  34 #include <epan/packet.h>
  35 #include "llcsaps.h"
  36 #include "ppptypes.h"
  37 #include <epan/resolv.h>
  38
  39 /* Offsets of fields within a BPDU */
  40
  41 #define BPDU_IDENTIFIER          0
  42 #define BPDU_VERSION_IDENTIFIER  2
  43 #define BPDU_TYPE                3
  44 #define BPDU_FLAGS               4
  45 #define BPDU_ROOT_IDENTIFIER     5
  46 #define BPDU_ROOT_PATH_COST     13
  47 #define BPDU_BRIDGE_IDENTIFIER  17
  48 #define BPDU_PORT_IDENTIFIER    25
  49 #define BPDU_MESSAGE_AGE        27
  50 #define BPDU_MAX_AGE            29
  51 #define BPDU_HELLO_TIME         31
  52 #define BPDU_FORWARD_DELAY      33
  53 #define BPDU_VERSION_1_LENGTH   35
  54
  55 #define CONF_BPDU_SIZE          35
  56 #define TC_BPDU_SIZE            4
  57 #define RST_BPDU_SIZE           36
  58
  59 /* Flag bits */
  60
  61 #define BPDU_FLAGS_TCACK                0x80
  62 #define BPDU_FLAGS_AGREEMENT            0x40
  63 #define BPDU_FLAGS_FORWARDING           0x20
  64 #define BPDU_FLAGS_LEARNING             0x10
  65 #define BPDU_FLAGS_PORT_ROLE_MASK       0x0C
  66 #define BPDU_FLAGS_PORT_ROLE_SHIFT      2
  67 #define BPDU_FLAGS_PROPOSAL             0x02
  68 #define BPDU_FLAGS_TC                   0x01
  69
  70 static int proto_bpdu = -1;
  71 static int hf_bpdu_proto_id = -1;
  72 static int hf_bpdu_version_id = -1;
  73 static int hf_bpdu_type = -1;
  74 static int hf_bpdu_flags = -1;
  75 static int hf_bpdu_flags_tcack = -1;
  76 static int hf_bpdu_flags_agreement = -1;
  77 static int hf_bpdu_flags_forwarding = -1;
  78 static int hf_bpdu_flags_learning = -1;
  79 static int hf_bpdu_flags_port_role = -1;
  80 static int hf_bpdu_flags_proposal = -1;
  81 static int hf_bpdu_flags_tc = -1;
  82 static int hf_bpdu_root_mac = -1;
  83 static int hf_bpdu_root_cost = -1;
  84 static int hf_bpdu_bridge_mac = -1;
  85 static int hf_bpdu_port_id = -1;
  86 static int hf_bpdu_msg_age = -1;
  87 static int hf_bpdu_max_age = -1;
  88 static int hf_bpdu_hello_time = -1;
  89 static int hf_bpdu_forward_delay = -1;
  90 static int hf_bpdu_version_1_length = -1;
  91
  92 static gint ett_bpdu = -1;
  93 static gint ett_bpdu_flags = -1;
  94
  95 static dissector_handle_t gvrp_handle;
  96 static dissector_handle_t gmrp_handle;
  97 static dissector_handle_t data_handle;
  98
  99 static const value_string protocol_id_vals[] = {
 100         { 0, "Spanning Tree Protocol" },
 101         { 0, NULL }
 102 };
 103
 104 #define BPDU_TYPE_CONF                  0x00
 105 #define BPDU_TYPE_RST                   0x02
 106 #define BPDU_TYPE_TOPOLOGY_CHANGE       0x80
 107
 108 static const value_string bpdu_type_vals[] = {
 109         { BPDU_TYPE_CONF,            "Configuration" },
 110         { BPDU_TYPE_RST,             "Rapid Spanning Tree" },
 111         { BPDU_TYPE_TOPOLOGY_CHANGE, "Topology Change Notification" },
 112         { 0,                         NULL }
 113 };
 114
 115 static const value_string role_vals[] = {
 116         { 1, "Alternate or Backup" },
 117         { 2, "Root" },
 118         { 3, "Designated" },
 119         { 0, NULL }
 120 };
 121
 122 static const char initial_sep[] = " (";
 123 static const char cont_sep[] = ", ";
 124
 125 #define APPEND_BOOLEAN_FLAG(flag, item, string) \
 126         if(flag){                                                       \
 127                 if(item)                                                \
 128                         proto_item_append_text(item, string, sep);      \
 129                 sep = cont_sep;                                         \
 130         }
 131
 132 static void
 133 dissect_bpdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 134 {
 135       guint16 protocol_identifier;
 136       guint8  protocol_version_identifier;
 137       guint8  bpdu_type;
 138       guint8  flags;
 139       guint16 root_identifier_bridge_priority;
 140       const guint8  *root_identifier_mac;
 141       gchar   *root_identifier_mac_str;
 142       guint32 root_path_cost;
 143       guint16 bridge_identifier_bridge_priority;
 144       const guint8  *bridge_identifier_mac;
 145       gchar   *bridge_identifier_mac_str;
 146       guint16 port_identifier;
 147       double message_age;
 148       double max_age;
 149       double hello_time;
 150       double forward_delay;
 151
 152       proto_tree *bpdu_tree;
 153       proto_item *bpdu_item;
 154       proto_tree *flags_tree;
 155       proto_item *flags_item;
 156       guint8    rstp_bpdu;
 157       const char *sep;
 158
 159       /* GARP application frames require special interpretation of the
 160          destination address field; otherwise, they will be mistaken as
 161          BPDU frames.
 162          Fortunately, they can be recognized by checking the first 6 octets
 163          of the destination address, which are in the range from
 164          01-80-C2-00-00-20 to 01-80-C2-00-00-2F.
 165
 166          Yes - we *do* need to check the destination address type;
 167          on Linux cooked captures, there *is* no destination address,
 168          so it's AT_NONE. */
 169       if (pinfo->dl_dst.type == AT_ETHER &&
 170           pinfo->dl_dst.data[0] == 0x01 && pinfo->dl_dst.data[1] == 0x80 &&
 171           pinfo->dl_dst.data[2] == 0xC2 && pinfo->dl_dst.data[3] == 0x00 &&
 172           pinfo->dl_dst.data[4] == 0x00 && ((pinfo->dl_dst.data[5] & 0x20) == 0x20)) {
 173
 174             protocol_identifier = tvb_get_ntohs(tvb, BPDU_IDENTIFIER);
 175
 176             switch (pinfo->dl_dst.data[5]) {
 177
 178             case 0x20:
 179                    /* for GMRP */
 180                   call_dissector(gmrp_handle, tvb, pinfo, tree);
 181                   return;
 182
 183             case 0x21:
 184                   /* for GVRP */
 185                   call_dissector(gvrp_handle, tvb, pinfo, tree);
 186                   return;
 187             }
 188
 189             pinfo->current_proto = "GARP";
 190
 191             if (check_col(pinfo->cinfo, COL_PROTOCOL)) {
 192                     col_set_str(pinfo->cinfo, COL_PROTOCOL, "GARP");
 193                     /* Generic Attribute Registration Protocol */
 194             }
 195
 196             if (check_col(pinfo->cinfo, COL_INFO)) {
 197                     col_add_fstr(pinfo->cinfo, COL_INFO,
 198                         "Unknown GARP application (0x%02X)",
 199                         pinfo->dl_dst.data[5]);
 200             }
 201
 202             return;
 203       }
 204
 205       if (check_col(pinfo->cinfo, COL_PROTOCOL)) {
 206             col_set_str(pinfo->cinfo, COL_PROTOCOL, "STP"); /* Spanning Tree Protocol */
 207       }
 208       if (check_col(pinfo->cinfo, COL_INFO)) {
 209             col_clear(pinfo->cinfo, COL_INFO);
 210       }
 211
 212       bpdu_type = tvb_get_guint8(tvb, BPDU_TYPE);
 213       switch (bpdu_type) {
 214
 215       case BPDU_TYPE_CONF:
 216       case BPDU_TYPE_RST:
 217             flags = tvb_get_guint8(tvb, BPDU_FLAGS);
 218             root_identifier_bridge_priority = tvb_get_ntohs(tvb,
 219                 BPDU_ROOT_IDENTIFIER);
 220             root_identifier_mac = tvb_get_ptr(tvb, BPDU_ROOT_IDENTIFIER + 2, 6);
 221             root_identifier_mac_str = ether_to_str(root_identifier_mac);
 222             root_path_cost = tvb_get_ntohl(tvb, BPDU_ROOT_PATH_COST);
 223             port_identifier = tvb_get_ntohs(tvb, BPDU_PORT_IDENTIFIER);
 224             break;
 225
 226       default:
 227             /* Squelch GCC complaints. */
 228             flags = 0;
 229             root_identifier_bridge_priority = 0;
 230             root_identifier_mac = NULL;
 231             root_identifier_mac_str = NULL;
 232             root_path_cost = 0;
 233             port_identifier = 0;
 234             break;
 235       }
 236
 237       if (check_col(pinfo->cinfo, COL_INFO)) {
 238             switch (bpdu_type) {
 239
 240             case BPDU_TYPE_CONF:
 241                   col_add_fstr(pinfo->cinfo, COL_INFO, "Conf. %sRoot = %d/%s  Cost = %d  Port = 0x%04x",
 242                                flags & 0x1 ? "TC + " : "",
 243                                root_identifier_bridge_priority, root_identifier_mac_str, root_path_cost,
 244                                port_identifier);
 245                   break;
 246
 247             case BPDU_TYPE_TOPOLOGY_CHANGE:
 248                   col_add_fstr(pinfo->cinfo, COL_INFO, "Topology Change Notification");
 249                   break;
 250
 251             case BPDU_TYPE_RST:
 252                   col_add_fstr(pinfo->cinfo, COL_INFO, "RST. %sRoot = %d/%s  Cost = %d  Port = 0x%04x",
 253                                flags & 0x1 ? "TC + " : "",
 254                                root_identifier_bridge_priority, root_identifier_mac_str, root_path_cost,
 255                                port_identifier);
 256                   break;
 257
 258             default:
 259                   col_add_fstr(pinfo->cinfo, COL_INFO, "Unknown BPDU type (%u)",
 260                                bpdu_type);
 261                   break;
 262             }
 263       }
 264
 265       switch (bpdu_type) {
 266
 267       case BPDU_TYPE_CONF:
 268         set_actual_length(tvb, CONF_BPDU_SIZE);
 269         break;
 270
 271       case BPDU_TYPE_TOPOLOGY_CHANGE:
 272         set_actual_length(tvb, TC_BPDU_SIZE);
 273         break;
 274
 275       case BPDU_TYPE_RST:
 276         set_actual_length(tvb, RST_BPDU_SIZE);
 277         break;
 278       }
 279
 280       if (tree) {
 281             bpdu_item = proto_tree_add_protocol_format(tree, proto_bpdu, tvb,
 282                                 0, -1, "Spanning Tree Protocol");
 283             bpdu_tree = proto_item_add_subtree(bpdu_item, ett_bpdu);
 284
 285             protocol_identifier = tvb_get_ntohs(tvb, BPDU_IDENTIFIER);
 286             proto_tree_add_uint(bpdu_tree, hf_bpdu_proto_id, tvb,
 287                                 BPDU_IDENTIFIER, 2, protocol_identifier);
 288
 289             protocol_version_identifier = tvb_get_guint8(tvb, BPDU_VERSION_IDENTIFIER);
 290             proto_tree_add_uint(bpdu_tree, hf_bpdu_version_id, tvb,
 291                                 BPDU_VERSION_IDENTIFIER, 1,
 292                                 protocol_version_identifier);
 293             switch (protocol_version_identifier) {
 294               case 0:
 295                 break;
 296               case 2:
 297                 break;
 298               default:
 299                   proto_tree_add_text(bpdu_tree, tvb, BPDU_VERSION_IDENTIFIER, 1,
 300                   "   (Warning: this version of Ethereal only knows about versions 0 & 2)");
 301                 break;
 302             }
 303             proto_tree_add_uint(bpdu_tree, hf_bpdu_type, tvb,
 304                                        BPDU_TYPE, 1,
 305                                        bpdu_type);
 306
 307             if (bpdu_type != BPDU_TYPE_CONF && bpdu_type != BPDU_TYPE_RST) {
 308               call_dissector(data_handle,
 309                              tvb_new_subset(tvb, BPDU_TYPE + 1, -1, -1),
 310                              pinfo, tree);
 311               return;
 312             }
 313
 314             rstp_bpdu = (bpdu_type == BPDU_TYPE_RST);
 315             bridge_identifier_bridge_priority = tvb_get_ntohs(tvb, BPDU_BRIDGE_IDENTIFIER);
 316             bridge_identifier_mac = tvb_get_ptr(tvb, BPDU_BRIDGE_IDENTIFIER + 2, 6);
 317             bridge_identifier_mac_str = ether_to_str(bridge_identifier_mac);
 318
 319             flags_item = proto_tree_add_uint(bpdu_tree, hf_bpdu_flags, tvb,
 320                                 BPDU_FLAGS, 1, flags);
 321             flags_tree = proto_item_add_subtree(flags_item, ett_bpdu_flags);
 322             sep = initial_sep;
 323             APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_TCACK, flags_item,
 324                                 "%sTopology Change Acknowledgment");
 325             proto_tree_add_boolean(flags_tree, hf_bpdu_flags_tcack, tvb,
 326                                 BPDU_FLAGS, 1, flags);
 327             if (rstp_bpdu) {
 328               APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_AGREEMENT, flags_item,
 329                                   "%sAgreement");
 330               proto_tree_add_boolean(flags_tree, hf_bpdu_flags_agreement, tvb,
 331                                   BPDU_FLAGS, 1, flags);
 332               APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_FORWARDING, flags_item,
 333                                   "%sForwarding");
 334               proto_tree_add_boolean(flags_tree, hf_bpdu_flags_forwarding, tvb,
 335                                   BPDU_FLAGS, 1, flags);
 336               APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_LEARNING, flags_item,
 337                                   "%sLearning");
 338               proto_tree_add_boolean(flags_tree, hf_bpdu_flags_learning, tvb,
 339                                   BPDU_FLAGS, 1, flags);
 340               if (flags_item) {
 341                 guint8 port_role;
 342
 343                 port_role = (flags & BPDU_FLAGS_PORT_ROLE_MASK) >> BPDU_FLAGS_PORT_ROLE_SHIFT;
 344                 proto_item_append_text(flags_item, "%sPort Role: %s", sep,
 345                                        val_to_str(port_role, role_vals,
 346                                                   "Unknown (%u)"));
 347               }
 348               sep = cont_sep;
 349               proto_tree_add_uint(flags_tree, hf_bpdu_flags_port_role, tvb,
 350                                   BPDU_FLAGS, 1, flags);
 351               APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_PROPOSAL, flags_item,
 352                                   "%sProposal");
 353               proto_tree_add_boolean(flags_tree, hf_bpdu_flags_proposal, tvb,
 354                                   BPDU_FLAGS, 1, flags);
 355             }
 356             APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_TC, flags_item,
 357                                 "%sTopology Change");
 358             proto_tree_add_boolean(flags_tree, hf_bpdu_flags_tc, tvb,
 359                                 BPDU_FLAGS, 1, flags);
 360             if (sep != initial_sep) {
 361               /* We put something in; put in the terminating ")" */
 362               proto_item_append_text(flags_item, ")");
 363             }
 364
 365             proto_tree_add_ether_hidden(bpdu_tree, hf_bpdu_root_mac, tvb,
 366                                        BPDU_ROOT_IDENTIFIER + 2, 6,
 367                                        root_identifier_mac);
 368             proto_tree_add_text(bpdu_tree, tvb,
 369                                 BPDU_ROOT_IDENTIFIER, 8,
 370                                 "Root Identifier: %d / %s",
 371                                 root_identifier_bridge_priority,
 372                                 root_identifier_mac_str);
 373             proto_tree_add_uint(bpdu_tree, hf_bpdu_root_cost, tvb,
 374                                 BPDU_ROOT_PATH_COST, 4,
 375                                 root_path_cost);
 376             proto_tree_add_text(bpdu_tree, tvb,
 377                                 BPDU_BRIDGE_IDENTIFIER, 8,
 378                                 "Bridge Identifier: %d / %s",
 379                                 bridge_identifier_bridge_priority,
 380                                 bridge_identifier_mac_str);
 381             proto_tree_add_ether_hidden(bpdu_tree, hf_bpdu_bridge_mac, tvb,
 382                                        BPDU_BRIDGE_IDENTIFIER + 2, 6,
 383                                        bridge_identifier_mac);
 384             proto_tree_add_uint(bpdu_tree, hf_bpdu_port_id, tvb,
 385                                 BPDU_PORT_IDENTIFIER, 2,
 386                                 port_identifier);
 387             message_age = tvb_get_ntohs(tvb, BPDU_MESSAGE_AGE) / 256.0;
 388             proto_tree_add_double(bpdu_tree, hf_bpdu_msg_age, tvb,
 389                                 BPDU_MESSAGE_AGE, 2,
 390                                 message_age);
 391             max_age = tvb_get_ntohs(tvb, BPDU_MAX_AGE) / 256.0;
 392             proto_tree_add_double(bpdu_tree, hf_bpdu_max_age, tvb,
 393                                 BPDU_MAX_AGE, 2,
 394                                 max_age);
 395             hello_time = tvb_get_ntohs(tvb, BPDU_HELLO_TIME) / 256.0;
 396             proto_tree_add_double(bpdu_tree, hf_bpdu_hello_time, tvb,
 397                                 BPDU_HELLO_TIME, 2,
 398                                 hello_time);
 399             forward_delay = tvb_get_ntohs(tvb, BPDU_FORWARD_DELAY) / 256.0;
 400             proto_tree_add_double(bpdu_tree, hf_bpdu_forward_delay, tvb,
 401                                 BPDU_FORWARD_DELAY, 2,
 402                                 forward_delay);
 403             if (rstp_bpdu) {
 404               proto_tree_add_item(bpdu_tree, hf_bpdu_version_1_length, tvb,
 405                                 BPDU_VERSION_1_LENGTH, 1, FALSE);
 406             }
 407       }
 408 }
 409
 410 static const true_false_string yesno = {
 411         "Yes",
 412         "No"
 413 };
 414
 415 void
 416 proto_register_bpdu(void)
 417 {
 418
 419   static hf_register_info hf[] = {
 420     { &hf_bpdu_proto_id,
 421       { "Protocol Identifier",          "stp.protocol",
 422         FT_UINT16,      BASE_HEX,       VALS(&protocol_id_vals), 0x0,
 423         "", HFILL }},
 424     { &hf_bpdu_version_id,
 425       { "Protocol Version Identifier",  "stp.version",
 426         FT_UINT8,       BASE_DEC,       NULL,   0x0,
 427         "", HFILL }},
 428     { &hf_bpdu_type,
 429       { "BPDU Type",                    "stp.type",
 430         FT_UINT8,       BASE_HEX,       VALS(&bpdu_type_vals),  0x0,
 431         "", HFILL }},
 432     { &hf_bpdu_flags,
 433       { "BPDU flags",                   "stp.flags",
 434         FT_UINT8,       BASE_HEX,       NULL,   0x0,
 435         "", HFILL }},
 436     { &hf_bpdu_flags_tcack,
 437       { "Topology Change Acknowledgment",  "stp.flags.tcack",
 438         FT_BOOLEAN,     8,              TFS(&yesno),    BPDU_FLAGS_TCACK,
 439         "", HFILL }},
 440     { &hf_bpdu_flags_agreement,
 441       { "Agreement",                    "stp.flags.agreement",
 442         FT_BOOLEAN,     8,              TFS(&yesno),    BPDU_FLAGS_AGREEMENT,
 443         "", HFILL }},
 444     { &hf_bpdu_flags_forwarding,
 445       { "Forwarding",                   "stp.flags.forwarding",
 446         FT_BOOLEAN,     8,              TFS(&yesno),    BPDU_FLAGS_FORWARDING,
 447         "", HFILL }},
 448     { &hf_bpdu_flags_learning,
 449       { "Learning",                     "stp.flags.learning",
 450         FT_BOOLEAN,     8,              TFS(&yesno),    BPDU_FLAGS_LEARNING,
 451         "", HFILL }},
 452     { &hf_bpdu_flags_port_role,
 453       { "Port Role",                    "stp.flags.port_role",
 454         FT_UINT8,       BASE_DEC,       VALS(role_vals),        BPDU_FLAGS_PORT_ROLE_MASK,
 455         "", HFILL }},
 456     { &hf_bpdu_flags_proposal,
 457       { "Proposal",                     "stp.flags.proposal",
 458         FT_BOOLEAN,     8,              TFS(&yesno),    BPDU_FLAGS_PROPOSAL,
 459         "", HFILL }},
 460     { &hf_bpdu_flags_tc,
 461       { "Topology Change",              "stp.flags.tc",
 462         FT_BOOLEAN,     8,              TFS(&yesno),    BPDU_FLAGS_TC,
 463         "", HFILL }},
 464     { &hf_bpdu_root_mac,
 465       { "Root Identifier",              "stp.root.hw",
 466         FT_ETHER,       BASE_NONE,      NULL,   0x0,
 467         "", HFILL }},
 468     { &hf_bpdu_root_cost,
 469       { "Root Path Cost",               "stp.root.cost",
 470         FT_UINT32,      BASE_DEC,       NULL,   0x0,
 471         "", HFILL }},
 472     { &hf_bpdu_bridge_mac,
 473       { "Bridge Identifier",            "stp.bridge.hw",
 474         FT_ETHER,       BASE_NONE,      NULL,   0x0,
 475         "", HFILL }},
 476     { &hf_bpdu_port_id,
 477       { "Port identifier",              "stp.port",
 478         FT_UINT16,      BASE_HEX,       NULL,   0x0,
 479         "", HFILL }},
 480     { &hf_bpdu_msg_age,
 481       { "Message Age",                  "stp.msg_age",
 482         FT_DOUBLE,      BASE_NONE,      NULL,   0x0,
 483         "", HFILL }},
 484     { &hf_bpdu_max_age,
 485       { "Max Age",                      "stp.max_age",
 486         FT_DOUBLE,      BASE_NONE,      NULL,   0x0,
 487         "", HFILL }},
 488     { &hf_bpdu_hello_time,
 489       { "Hello Time",                   "stp.hello",
 490         FT_DOUBLE,      BASE_NONE,      NULL,   0x0,
 491         "", HFILL }},
 492     { &hf_bpdu_forward_delay,
 493       { "Forward Delay",                "stp.forward",
 494         FT_DOUBLE,      BASE_NONE,      NULL,   0x0,
 495         "", HFILL }},
 496     { &hf_bpdu_version_1_length,
 497       { "Version 1 Length",             "stp.version_1_length",
 498         FT_UINT8,       BASE_DEC,       NULL,   0x0,
 499         "", HFILL }},
 500   };
 501   static gint *ett[] = {
 502     &ett_bpdu,
 503     &ett_bpdu_flags,
 504   };
 505
 506   proto_bpdu = proto_register_protocol("Spanning Tree Protocol", "STP", "stp");
 507   proto_register_field_array(proto_bpdu, hf, array_length(hf));
 508   proto_register_subtree_array(ett, array_length(ett));
 509
 510   register_dissector("bpdu", dissect_bpdu, proto_bpdu);
 511 }
 512
 513 void
 514 proto_reg_handoff_bpdu(void)
 515 {
 516   dissector_handle_t bpdu_handle;
 517
 518   /*
 519    * Get handle for the GVRP dissector.
 520    */
 521   gvrp_handle = find_dissector("gvrp");
 522
 523   /*
 524    * Get handle for the GMRP dissector.
 525    */
 526   gmrp_handle = find_dissector("gmrp");
 527   data_handle = find_dissector("data");
 528
 529   bpdu_handle = find_dissector("bpdu");
 530   dissector_add("llc.dsap", SAP_BPDU, bpdu_handle);
 531   dissector_add("ppp.protocol", PPP_BPDU, bpdu_handle);
 532 }