packet-bpdu.c

   1 /* packet-bpdu.c
   2  * Routines for BPDU (Spanning Tree Protocol) disassembly
   3  *
   4  * $Id: packet-bpdu.c,v 1.35 2002/03/31 21:33:51 guy 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 #ifdef HAVE_SYS_TYPES_H
  32 # include <sys/types.h>
  33 #endif
  34
  35 #ifdef HAVE_NETINET_IN_H
  36 # include <netinet/in.h>
  37 #endif
  38
  39 #include <stdio.h>
  40 #include <string.h>
  41 #include <glib.h>
  42 #include <epan/packet.h>
  43 #include "llcsaps.h"
  44 #include "ppptypes.h"
  45 #include <epan/resolv.h>
  46
  47 /* Offsets of fields within a BPDU */
  48
  49 #define BPDU_IDENTIFIER          0
  50 #define BPDU_VERSION_IDENTIFIER  2
  51 #define BPDU_TYPE                3
  52 #define BPDU_FLAGS               4
  53 #define BPDU_ROOT_IDENTIFIER     5
  54 #define BPDU_ROOT_PATH_COST     13
  55 #define BPDU_BRIDGE_IDENTIFIER  17
  56 #define BPDU_PORT_IDENTIFIER    25
  57 #define BPDU_MESSAGE_AGE        27
  58 #define BPDU_MAX_AGE            29
  59 #define BPDU_HELLO_TIME         31
  60 #define BPDU_FORWARD_DELAY      33
  61 #define BPDU_VERSION_1_LENGTH   35
  62
  63 #define CONF_BPDU_SIZE          35
  64 #define TC_BPDU_SIZE            4
  65 #define RST_BPDU_SIZE           36
  66
  67 /* Flag bits */
  68
  69 #define BPDU_FLAGS_TCACK                0x80
  70 #define BPDU_FLAGS_AGREEMENT            0x40
  71 #define BPDU_FLAGS_FORWARDING           0x20
  72 #define BPDU_FLAGS_LEARNING             0x10
  73 #define BPDU_FLAGS_PORT_ROLE_MASK       0x0C
  74 #define BPDU_FLAGS_PORT_ROLE_SHIFT      2
  75 #define BPDU_FLAGS_PROPOSAL             0x02
  76 #define BPDU_FLAGS_TC                   0x01
  77
  78 static int proto_bpdu = -1;
  79 static int hf_bpdu_proto_id = -1;
  80 static int hf_bpdu_version_id = -1;
  81 static int hf_bpdu_type = -1;
  82 static int hf_bpdu_flags = -1;
  83 static int hf_bpdu_flags_tcack = -1;
  84 static int hf_bpdu_flags_agreement = -1;
  85 static int hf_bpdu_flags_forwarding = -1;
  86 static int hf_bpdu_flags_learning = -1;
  87 static int hf_bpdu_flags_port_role = -1;
  88 static int hf_bpdu_flags_proposal = -1;
  89 static int hf_bpdu_flags_tc = -1;
  90 static int hf_bpdu_root_mac = -1;
  91 static int hf_bpdu_root_cost = -1;
  92 static int hf_bpdu_bridge_mac = -1;
  93 static int hf_bpdu_port_id = -1;
  94 static int hf_bpdu_msg_age = -1;
  95 static int hf_bpdu_max_age = -1;
  96 static int hf_bpdu_hello_time = -1;
  97 static int hf_bpdu_forward_delay = -1;
  98 static int hf_bpdu_version_1_length = -1;
  99
 100 static gint ett_bpdu = -1;
 101 static gint ett_bpdu_flags = -1;
 102
 103 static dissector_handle_t gvrp_handle;
 104 static dissector_handle_t gmrp_handle;
 105 static dissector_handle_t data_handle;
 106
 107 static const value_string protocol_id_vals[] = {
 108         { 0, "Spanning Tree Protocol" },
 109         { 0, NULL }
 110 };
 111
 112 #define BPDU_TYPE_CONF                  0x00
 113 #define BPDU_TYPE_RST                   0x02
 114 #define BPDU_TYPE_TOPOLOGY_CHANGE       0x80
 115
 116 static const value_string bpdu_type_vals[] = {
 117         { BPDU_TYPE_CONF,            "Configuration" },
 118         { BPDU_TYPE_RST,             "Rapid Spanning Tree" },
 119         { BPDU_TYPE_TOPOLOGY_CHANGE, "Topology Change Notification" },
 120         { 0,                         NULL }
 121 };
 122
 123 static const value_string role_vals[] = {
 124         { 1, "Alternate or Backup" },
 125         { 2, "Root" },
 126         { 3, "Designated" },
 127         { 0, NULL }
 128 };
 129
 130 static const char initial_sep[] = " (";
 131 static const char cont_sep[] = ", ";
 132
 133 #define APPEND_BOOLEAN_FLAG(flag, item, string) \
 134         if(flag){                                                       \
 135                 if(item)                                                \
 136                         proto_item_append_text(item, string, sep);      \
 137                 sep = cont_sep;                                         \
 138         }
 139
 140 static void
 141 dissect_bpdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 142 {
 143       guint16 protocol_identifier;
 144       guint8  protocol_version_identifier;
 145       guint8  bpdu_type;
 146       guint8  flags;
 147       guint16 root_identifier_bridge_priority;
 148       const guint8  *root_identifier_mac;
 149       gchar   *root_identifier_mac_str;
 150       guint32 root_path_cost;
 151       guint16 bridge_identifier_bridge_priority;
 152       const guint8  *bridge_identifier_mac;
 153       gchar   *bridge_identifier_mac_str;
 154       guint16 port_identifier;
 155       double message_age;
 156       double max_age;
 157       double hello_time;
 158       double forward_delay;
 159
 160       proto_tree *bpdu_tree;
 161       proto_item *bpdu_item;
 162       proto_tree *flags_tree;
 163       proto_item *flags_item;
 164       guint8    rstp_bpdu;
 165       const char *sep;
 166
 167       /* GARP application frames require special interpretation of the
 168          destination address field; otherwise, they will be mistaken as
 169          BPDU frames.
 170          Fortunately, they can be recognized by checking the first 6 octets
 171          of the destination address, which are in the range from
 172          01-80-C2-00-00-20 to 01-80-C2-00-00-2F.
 173
 174          Yes - we *do* need to check the destination address type;
 175          on Linux cooked captures, there *is* no destination address,
 176          so it's AT_NONE. */
 177       if (pinfo->dl_dst.type == AT_ETHER &&
 178           pinfo->dl_dst.data[0] == 0x01 && pinfo->dl_dst.data[1] == 0x80 &&
 179           pinfo->dl_dst.data[2] == 0xC2 && pinfo->dl_dst.data[3] == 0x00 &&
 180           pinfo->dl_dst.data[4] == 0x00 && ((pinfo->dl_dst.data[5] & 0x20) == 0x20)) {
 181
 182             protocol_identifier = tvb_get_ntohs(tvb, BPDU_IDENTIFIER);
 183
 184             switch (pinfo->dl_dst.data[5]) {
 185
 186             case 0x20:
 187                    /* for GMRP */
 188                   call_dissector(gmrp_handle, tvb, pinfo, tree);
 189                   return;
 190
 191             case 0x21:
 192                   /* for GVRP */
 193                   call_dissector(gvrp_handle, tvb, pinfo, tree);
 194                   return;
 195             }
 196
 197             pinfo->current_proto = "GARP";
 198
 199             if (check_col(pinfo->cinfo, COL_PROTOCOL)) {
 200                     col_set_str(pinfo->cinfo, COL_PROTOCOL, "GARP");
 201                     /* Generic Attribute Registration Protocol */
 202             }
 203
 204             if (check_col(pinfo->cinfo, COL_INFO)) {
 205                     col_add_fstr(pinfo->cinfo, COL_INFO,
 206                         "Unknown GARP application (0x%02X)",
 207                         pinfo->dl_dst.data[5]);
 208             }
 209
 210             return;
 211       }
 212
 213       if (check_col(pinfo->cinfo, COL_PROTOCOL)) {
 214             col_set_str(pinfo->cinfo, COL_PROTOCOL, "STP"); /* Spanning Tree Protocol */
 215       }
 216       if (check_col(pinfo->cinfo, COL_INFO)) {
 217             col_clear(pinfo->cinfo, COL_INFO);
 218       }
 219
 220       bpdu_type = tvb_get_guint8(tvb, BPDU_TYPE);
 221       switch (bpdu_type) {
 222
 223       case BPDU_TYPE_CONF:
 224       case BPDU_TYPE_RST:
 225             flags = tvb_get_guint8(tvb, BPDU_FLAGS);
 226             root_identifier_bridge_priority = tvb_get_ntohs(tvb,
 227                 BPDU_ROOT_IDENTIFIER);
 228             root_identifier_mac = tvb_get_ptr(tvb, BPDU_ROOT_IDENTIFIER + 2, 6);
 229             root_identifier_mac_str = ether_to_str(root_identifier_mac);
 230             root_path_cost = tvb_get_ntohl(tvb, BPDU_ROOT_PATH_COST);
 231             port_identifier = tvb_get_ntohs(tvb, BPDU_PORT_IDENTIFIER);
 232             break;
 233
 234       default:
 235             /* Squelch GCC complaints. */
 236             flags = 0;
 237             root_identifier_bridge_priority = 0;
 238             root_identifier_mac = NULL;
 239             root_identifier_mac_str = NULL;
 240             root_path_cost = 0;
 241             port_identifier = 0;
 242             break;
 243       }
 244
 245       if (check_col(pinfo->cinfo, COL_INFO)) {
 246             switch (bpdu_type) {
 247
 248             case BPDU_TYPE_CONF:
 249                   col_add_fstr(pinfo->cinfo, COL_INFO, "Conf. %sRoot = %d/%s  Cost = %d  Port = 0x%04x",
 250                                flags & 0x1 ? "TC + " : "",
 251                                root_identifier_bridge_priority, root_identifier_mac_str, root_path_cost,
 252                                port_identifier);
 253                   break;
 254
 255             case BPDU_TYPE_TOPOLOGY_CHANGE:
 256                   col_add_fstr(pinfo->cinfo, COL_INFO, "Topology Change Notification");
 257                   break;
 258
 259             case BPDU_TYPE_RST:
 260                   col_add_fstr(pinfo->cinfo, COL_INFO, "RST. %sRoot = %d/%s  Cost = %d  Port = 0x%04x",
 261                                flags & 0x1 ? "TC + " : "",
 262                                root_identifier_bridge_priority, root_identifier_mac_str, root_path_cost,
 263                                port_identifier);
 264                   break;
 265
 266             default:
 267                   col_add_fstr(pinfo->cinfo, COL_INFO, "Unknown BPDU type (%u)",
 268                                bpdu_type);
 269                   break;
 270             }
 271       }
 272
 273       switch (bpdu_type) {
 274
 275       case BPDU_TYPE_CONF:
 276         set_actual_length(tvb, CONF_BPDU_SIZE);
 277         break;
 278
 279       case BPDU_TYPE_TOPOLOGY_CHANGE:
 280         set_actual_length(tvb, TC_BPDU_SIZE);
 281         break;
 282
 283       case BPDU_TYPE_RST:
 284         set_actual_length(tvb, RST_BPDU_SIZE);
 285         break;
 286       }
 287
 288       if (tree) {
 289             bpdu_item = proto_tree_add_protocol_format(tree, proto_bpdu, tvb,
 290                                 0, -1, "Spanning Tree Protocol");
 291             bpdu_tree = proto_item_add_subtree(bpdu_item, ett_bpdu);
 292
 293             protocol_identifier = tvb_get_ntohs(tvb, BPDU_IDENTIFIER);
 294             proto_tree_add_uint(bpdu_tree, hf_bpdu_proto_id, tvb,
 295                                 BPDU_IDENTIFIER, 2, protocol_identifier);
 296
 297             protocol_version_identifier = tvb_get_guint8(tvb, BPDU_VERSION_IDENTIFIER);
 298             proto_tree_add_uint(bpdu_tree, hf_bpdu_version_id, tvb,
 299                                 BPDU_VERSION_IDENTIFIER, 1,
 300                                 protocol_version_identifier);
 301             switch (protocol_version_identifier) {
 302               case 0:
 303                 break;
 304               case 2:
 305                 break;
 306               default:
 307                   proto_tree_add_text(bpdu_tree, tvb, BPDU_VERSION_IDENTIFIER, 1,
 308                   "   (Warning: this version of Ethereal only knows about versions 0 & 2)");
 309                 break;
 310             }
 311             proto_tree_add_uint(bpdu_tree, hf_bpdu_type, tvb,
 312                                        BPDU_TYPE, 1,
 313                                        bpdu_type);
 314
 315             if (bpdu_type != BPDU_TYPE_CONF && bpdu_type != BPDU_TYPE_RST) {
 316               call_dissector(data_handle,tvb_new_subset(tvb, BPDU_TYPE + 1,-1,tvb_reported_length_remaining(tvb,BPDU_TYPE + 1)), pinfo, tree);
 317               return;
 318             }
 319
 320             rstp_bpdu = (bpdu_type == BPDU_TYPE_RST);
 321             bridge_identifier_bridge_priority = tvb_get_ntohs(tvb, BPDU_BRIDGE_IDENTIFIER);
 322             bridge_identifier_mac = tvb_get_ptr(tvb, BPDU_BRIDGE_IDENTIFIER + 2, 6);
 323             bridge_identifier_mac_str = ether_to_str(bridge_identifier_mac);
 324
 325             flags_item = proto_tree_add_uint(bpdu_tree, hf_bpdu_flags, tvb,
 326                                 BPDU_FLAGS, 1, flags);
 327             flags_tree = proto_item_add_subtree(flags_item, ett_bpdu_flags);
 328             sep = initial_sep;
 329             APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_TCACK, flags_item,
 330                                 "%sTopology Change Acknowledgment");
 331             proto_tree_add_boolean(flags_tree, hf_bpdu_flags_tcack, tvb,
 332                                 BPDU_FLAGS, 1, flags);
 333             if (rstp_bpdu) {
 334               APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_AGREEMENT, flags_item,
 335                                   "%sAgreement");
 336               proto_tree_add_boolean(flags_tree, hf_bpdu_flags_agreement, tvb,
 337                                   BPDU_FLAGS, 1, flags);
 338               APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_FORWARDING, flags_item,
 339                                   "%sForwarding");
 340               proto_tree_add_boolean(flags_tree, hf_bpdu_flags_forwarding, tvb,
 341                                   BPDU_FLAGS, 1, flags);
 342               APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_LEARNING, flags_item,
 343                                   "%sLearning");
 344               proto_tree_add_boolean(flags_tree, hf_bpdu_flags_learning, tvb,
 345                                   BPDU_FLAGS, 1, flags);
 346               if (flags_item) {
 347                 guint8 port_role;
 348
 349                 port_role = (flags & BPDU_FLAGS_PORT_ROLE_MASK) >> BPDU_FLAGS_PORT_ROLE_SHIFT;
 350                 proto_item_append_text(flags_item, "%sPort Role: %s", sep,
 351                                        val_to_str(port_role, role_vals,
 352                                                   "Unknown (%u)"));
 353               }
 354               sep = cont_sep;
 355               proto_tree_add_uint(flags_tree, hf_bpdu_flags_port_role, tvb,
 356                                   BPDU_FLAGS, 1, flags);
 357               APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_PROPOSAL, flags_item,
 358                                   "%sProposal");
 359               proto_tree_add_boolean(flags_tree, hf_bpdu_flags_proposal, tvb,
 360                                   BPDU_FLAGS, 1, flags);
 361             }
 362             APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_TC, flags_item,
 363                                 "%sTopology Change");
 364             proto_tree_add_boolean(flags_tree, hf_bpdu_flags_tc, tvb,
 365                                 BPDU_FLAGS, 1, flags);
 366             if (sep != initial_sep) {
 367               /* We put something in; put in the terminating ")" */
 368               proto_item_append_text(flags_item, ")");
 369             }
 370
 371             proto_tree_add_ether_hidden(bpdu_tree, hf_bpdu_root_mac, tvb,
 372                                        BPDU_ROOT_IDENTIFIER + 2, 6,
 373                                        root_identifier_mac);
 374             proto_tree_add_text(bpdu_tree, tvb,
 375                                 BPDU_ROOT_IDENTIFIER, 8,
 376                                 "Root Identifier: %d / %s",
 377                                 root_identifier_bridge_priority,
 378                                 root_identifier_mac_str);
 379             proto_tree_add_uint(bpdu_tree, hf_bpdu_root_cost, tvb,
 380                                 BPDU_ROOT_PATH_COST, 4,
 381                                 root_path_cost);
 382             proto_tree_add_text(bpdu_tree, tvb,
 383                                 BPDU_BRIDGE_IDENTIFIER, 8,
 384                                 "Bridge Identifier: %d / %s",
 385                                 bridge_identifier_bridge_priority,
 386                                 bridge_identifier_mac_str);
 387             proto_tree_add_ether_hidden(bpdu_tree, hf_bpdu_bridge_mac, tvb,
 388                                        BPDU_BRIDGE_IDENTIFIER + 2, 6,
 389                                        bridge_identifier_mac);
 390             proto_tree_add_uint(bpdu_tree, hf_bpdu_port_id, tvb,
 391                                 BPDU_PORT_IDENTIFIER, 2,
 392                                 port_identifier);
 393             message_age = tvb_get_ntohs(tvb, BPDU_MESSAGE_AGE) / 256.0;
 394             proto_tree_add_double(bpdu_tree, hf_bpdu_msg_age, tvb,
 395                                 BPDU_MESSAGE_AGE, 2,
 396                                 message_age);
 397             max_age = tvb_get_ntohs(tvb, BPDU_MAX_AGE) / 256.0;
 398             proto_tree_add_double(bpdu_tree, hf_bpdu_max_age, tvb,
 399                                 BPDU_MAX_AGE, 2,
 400                                 max_age);
 401             hello_time = tvb_get_ntohs(tvb, BPDU_HELLO_TIME) / 256.0;
 402             proto_tree_add_double(bpdu_tree, hf_bpdu_hello_time, tvb,
 403                                 BPDU_HELLO_TIME, 2,
 404                                 hello_time);
 405             forward_delay = tvb_get_ntohs(tvb, BPDU_FORWARD_DELAY) / 256.0;
 406             proto_tree_add_double(bpdu_tree, hf_bpdu_forward_delay, tvb,
 407                                 BPDU_FORWARD_DELAY, 2,
 408                                 forward_delay);
 409             if (rstp_bpdu) {
 410               proto_tree_add_item(bpdu_tree, hf_bpdu_version_1_length, tvb,
 411                                 BPDU_VERSION_1_LENGTH, 1, FALSE);
 412             }
 413       }
 414 }
 415
 416 static const true_false_string yesno = {
 417         "Yes",
 418         "No"
 419 };
 420
 421 void
 422 proto_register_bpdu(void)
 423 {
 424
 425   static hf_register_info hf[] = {
 426     { &hf_bpdu_proto_id,
 427       { "Protocol Identifier",          "stp.protocol",
 428         FT_UINT16,      BASE_HEX,       VALS(&protocol_id_vals), 0x0,
 429         "", HFILL }},
 430     { &hf_bpdu_version_id,
 431       { "Protocol Version Identifier",  "stp.version",
 432         FT_UINT8,       BASE_DEC,       NULL,   0x0,
 433         "", HFILL }},
 434     { &hf_bpdu_type,
 435       { "BPDU Type",                    "stp.type",
 436         FT_UINT8,       BASE_HEX,       VALS(&bpdu_type_vals),  0x0,
 437         "", HFILL }},
 438     { &hf_bpdu_flags,
 439       { "BPDU flags",                   "stp.flags",
 440         FT_UINT8,       BASE_HEX,       NULL,   0x0,
 441         "", HFILL }},
 442     { &hf_bpdu_flags_tcack,
 443       { "Topology Change Acknowledgment",  "stp.flags.tcack",
 444         FT_BOOLEAN,     8,              TFS(&yesno),    BPDU_FLAGS_TCACK,
 445         "", HFILL }},
 446     { &hf_bpdu_flags_agreement,
 447       { "Agreement",                    "stp.flags.agreement",
 448         FT_BOOLEAN,     8,              TFS(&yesno),    BPDU_FLAGS_AGREEMENT,
 449         "", HFILL }},
 450     { &hf_bpdu_flags_forwarding,
 451       { "Forwarding",                   "stp.flags.forwarding",
 452         FT_BOOLEAN,     8,              TFS(&yesno),    BPDU_FLAGS_FORWARDING,
 453         "", HFILL }},
 454     { &hf_bpdu_flags_learning,
 455       { "Learning",                     "stp.flags.learning",
 456         FT_BOOLEAN,     8,              TFS(&yesno),    BPDU_FLAGS_LEARNING,
 457         "", HFILL }},
 458     { &hf_bpdu_flags_port_role,
 459       { "Port Role",                    "stp.flags.port_role",
 460         FT_UINT8,       BASE_DEC,       VALS(role_vals),        BPDU_FLAGS_PORT_ROLE_MASK,
 461         "", HFILL }},
 462     { &hf_bpdu_flags_proposal,
 463       { "Proposal",                     "stp.flags.proposal",
 464         FT_BOOLEAN,     8,              TFS(&yesno),    BPDU_FLAGS_PROPOSAL,
 465         "", HFILL }},
 466     { &hf_bpdu_flags_tc,
 467       { "Topology Change",              "stp.flags.tc",
 468         FT_BOOLEAN,     8,              TFS(&yesno),    BPDU_FLAGS_TC,
 469         "", HFILL }},
 470     { &hf_bpdu_root_mac,
 471       { "Root Identifier",              "stp.root.hw",
 472         FT_ETHER,       BASE_NONE,      NULL,   0x0,
 473         "", HFILL }},
 474     { &hf_bpdu_root_cost,
 475       { "Root Path Cost",               "stp.root.cost",
 476         FT_UINT32,      BASE_DEC,       NULL,   0x0,
 477         "", HFILL }},
 478     { &hf_bpdu_bridge_mac,
 479       { "Bridge Identifier",            "stp.bridge.hw",
 480         FT_ETHER,       BASE_NONE,      NULL,   0x0,
 481         "", HFILL }},
 482     { &hf_bpdu_port_id,
 483       { "Port identifier",              "stp.port",
 484         FT_UINT16,      BASE_HEX,       NULL,   0x0,
 485         "", HFILL }},
 486     { &hf_bpdu_msg_age,
 487       { "Message Age",                  "stp.msg_age",
 488         FT_DOUBLE,      BASE_NONE,      NULL,   0x0,
 489         "", HFILL }},
 490     { &hf_bpdu_max_age,
 491       { "Max Age",                      "stp.max_age",
 492         FT_DOUBLE,      BASE_NONE,      NULL,   0x0,
 493         "", HFILL }},
 494     { &hf_bpdu_hello_time,
 495       { "Hello Time",                   "stp.hello",
 496         FT_DOUBLE,      BASE_NONE,      NULL,   0x0,
 497         "", HFILL }},
 498     { &hf_bpdu_forward_delay,
 499       { "Forward Delay",                "stp.forward",
 500         FT_DOUBLE,      BASE_NONE,      NULL,   0x0,
 501         "", HFILL }},
 502     { &hf_bpdu_version_1_length,
 503       { "Version 1 Length",             "stp.version_1_length",
 504         FT_UINT8,       BASE_DEC,       NULL,   0x0,
 505         "", HFILL }},
 506   };
 507   static gint *ett[] = {
 508     &ett_bpdu,
 509     &ett_bpdu_flags,
 510   };
 511
 512   proto_bpdu = proto_register_protocol("Spanning Tree Protocol", "STP", "stp");
 513   proto_register_field_array(proto_bpdu, hf, array_length(hf));
 514   proto_register_subtree_array(ett, array_length(ett));
 515
 516   register_dissector("bpdu", dissect_bpdu, proto_bpdu);
 517 }
 518
 519 void
 520 proto_reg_handoff_bpdu(void)
 521 {
 522   dissector_handle_t bpdu_handle;
 523
 524   /*
 525    * Get handle for the GVRP dissector.
 526    */
 527   gvrp_handle = find_dissector("gvrp");
 528
 529   /*
 530    * Get handle for the GMRP dissector.
 531    */
 532   gmrp_handle = find_dissector("gmrp");
 533   data_handle = find_dissector("data");
 534
 535   bpdu_handle = find_dissector("bpdu");
 536   dissector_add("llc.dsap", SAP_BPDU, bpdu_handle);
 537   dissector_add("ppp.protocol", PPP_BPDU, bpdu_handle);
 538 }