packet-bpdu.c

   1 /* packet-bpdu.c
   2  * Routines for BPDU (Spanning Tree Protocol) disassembly
   3  *
   4  * $Id: packet-bpdu.c,v 1.45 2003/01/11 10:16:22 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 #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 "chdlctypes.h"
  38 #include <epan/resolv.h>
  39
  40 /* Offsets of fields within a BPDU */
  41
  42 #define BPDU_IDENTIFIER          0
  43 #define BPDU_VERSION_IDENTIFIER  2
  44 #define BPDU_TYPE                3
  45 #define BPDU_FLAGS               4
  46 #define BPDU_ROOT_IDENTIFIER     5
  47 #define BPDU_ROOT_PATH_COST     13
  48 #define BPDU_BRIDGE_IDENTIFIER  17
  49 #define BPDU_PORT_IDENTIFIER    25
  50 #define BPDU_MESSAGE_AGE        27
  51 #define BPDU_MAX_AGE            29
  52 #define BPDU_HELLO_TIME         31
  53 #define BPDU_FORWARD_DELAY      33
  54 #define BPDU_VERSION_1_LENGTH   35
  55 #define BPDU_VERSION_3_LENGTH   36
  56 #define BPDU_MST_CONFIG_FORMAT_SELECTOR 38
  57 #define BPDU_MST_CONFIG_NAME 39
  58 #define BPDU_MST_CONFIG_REVISION_LEVEL 71
  59 #define BPDU_MST_CONFIG_DIGEST 73
  60 #define BPDU_CIST_INTERNAL_ROOT_PATH_COST 89
  61 #define BPDU_CIST_BRIDGE_IDENTIFIER 93
  62 #define BPDU_CIST_REMAINING_HOPS        101
  63 #define BPDU_MSTI                       102
  64 #define MSTI_FLAGS                      0
  65 #define MSTI_REGIONAL_ROOT              1
  66 #define MSTI_INTERNAL_ROOT_PATH_COST    9
  67 #define MSTI_BRIDGE_IDENTIFIER_PRIORITY 13
  68 #define MSTI_PORT_IDENTIFIER_PRIORITY   14
  69 #define MSTI_REMAINING_HOPS             15
  70
  71 #define CONF_BPDU_SIZE          35
  72 #define TC_BPDU_SIZE            4
  73 #define RST_BPDU_SIZE           36
  74 #define VERSION_3_STATIC_LENGTH 64
  75 #define MSTI_MESSAGE_SIZE       16
  76
  77 /* Flag bits */
  78
  79 #define BPDU_FLAGS_TCACK                0x80
  80 #define BPDU_FLAGS_AGREEMENT            0x40
  81 #define BPDU_FLAGS_FORWARDING           0x20
  82 #define BPDU_FLAGS_LEARNING             0x10
  83 #define BPDU_FLAGS_PORT_ROLE_MASK       0x0C
  84 #define BPDU_FLAGS_PORT_ROLE_SHIFT      2
  85 #define BPDU_FLAGS_PROPOSAL             0x02
  86 #define BPDU_FLAGS_TC                   0x01
  87
  88 static int proto_bpdu = -1;
  89 static int hf_bpdu_proto_id = -1;
  90 static int hf_bpdu_version_id = -1;
  91 static int hf_bpdu_type = -1;
  92 static int hf_bpdu_flags = -1;
  93 static int hf_bpdu_flags_tcack = -1;
  94 static int hf_bpdu_flags_agreement = -1;
  95 static int hf_bpdu_flags_forwarding = -1;
  96 static int hf_bpdu_flags_learning = -1;
  97 static int hf_bpdu_flags_port_role = -1;
  98 static int hf_bpdu_flags_proposal = -1;
  99 static int hf_bpdu_flags_tc = -1;
 100 static int hf_bpdu_root_mac = -1;
 101 static int hf_bpdu_root_cost = -1;
 102 static int hf_bpdu_bridge_mac = -1;
 103 static int hf_bpdu_port_id = -1;
 104 static int hf_bpdu_msg_age = -1;
 105 static int hf_bpdu_max_age = -1;
 106 static int hf_bpdu_hello_time = -1;
 107 static int hf_bpdu_forward_delay = -1;
 108 static int hf_bpdu_version_1_length = -1;
 109 static int hf_bpdu_version_3_length = -1;
 110 static int hf_bpdu_mst_config_format_selector = -1;
 111 static int hf_bpdu_mst_config_name = -1;
 112 static int hf_bpdu_mst_config_revision_level = -1;
 113 static int hf_bpdu_mst_config_digest = -1;
 114 static int hf_bpdu_cist_internal_root_path_cost = -1;
 115 static int hf_bpdu_cist_bridge_identifier_mac = -1;
 116 static int hf_bpdu_cist_remaining_hops = -1;
 117 static int hf_bpdu_msti_flags = -1;
 118 static int hf_bpdu_msti_regional_root_mac = -1;
 119 static int hf_bpdu_msti_internal_root_path_cost = -1;
 120 static int hf_bpdu_msti_bridge_identifier_priority = -1;
 121 static int hf_bpdu_msti_port_identifier_priority = -1;
 122 static int hf_bpdu_msti_remaining_hops = -1;
 123
 124 static gint ett_bpdu = -1;
 125 static gint ett_bpdu_flags = -1;
 126 static gint ett_mstp = -1;
 127 static gint ett_msti = -1;
 128
 129 static dissector_handle_t gvrp_handle;
 130 static dissector_handle_t gmrp_handle;
 131 static dissector_handle_t data_handle;
 132
 133 static const value_string protocol_id_vals[] = {
 134         { 0, "Spanning Tree Protocol" },
 135         { 0, NULL }
 136 };
 137
 138 #define BPDU_TYPE_CONF                  0x00    /* STP Configuration BPDU */
 139 #define BPDU_TYPE_RST                   0x02    /* RST BPDU (or MST) */
 140 #define BPDU_TYPE_TOPOLOGY_CHANGE       0x80    /* STP TCN (Topology change notify) BPDU */
 141
 142 static const value_string bpdu_type_vals[] = {
 143         { BPDU_TYPE_CONF,            "Configuration" },
 144         { BPDU_TYPE_RST,             "Rapid/Multiple Spanning Tree" },
 145         { BPDU_TYPE_TOPOLOGY_CHANGE, "Topology Change Notification" },
 146         { 0,                         NULL }
 147 };
 148
 149 #define PROTO_VERSION_STP       0
 150 #define PROTO_VERSION_RSTP      2
 151 #define PROTO_VERSION_MSTP      3
 152
 153 static const value_string version_id_vals[] = {
 154         { PROTO_VERSION_STP,    "Spanning Tree" },
 155         { PROTO_VERSION_RSTP,   "Rapid Spanning Tree" },
 156         { PROTO_VERSION_MSTP,   "Multiple Spanning Tree" },
 157         { 0,                    NULL}
 158 };
 159 static const value_string role_vals[] = {
 160         { 1, "Alternate or Backup" },
 161         { 2, "Root" },
 162         { 3, "Designated" },
 163         { 0, NULL }
 164 };
 165
 166 static const char initial_sep[] = " (";
 167 static const char cont_sep[] = ", ";
 168
 169 #define APPEND_BOOLEAN_FLAG(flag, item, string) \
 170         if(flag){                                                       \
 171                 if(item)                                                \
 172                         proto_item_append_text(item, string, sep);      \
 173                 sep = cont_sep;                                         \
 174         }
 175
 176 static void
 177 dissect_bpdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 178 {
 179       guint16 protocol_identifier;
 180       guint8  protocol_version_identifier;
 181       guint8  bpdu_type;
 182       guint8  flags;
 183       guint16 root_identifier_bridge_priority;
 184       const guint8  *root_identifier_mac;
 185       gchar   *root_identifier_mac_str;
 186       guint32 root_path_cost;
 187       guint16 bridge_identifier_bridge_priority;
 188       const guint8  *bridge_identifier_mac;
 189       gchar   *bridge_identifier_mac_str;
 190       guint16 port_identifier;
 191       double message_age;
 192       double max_age;
 193       double hello_time;
 194       double forward_delay;
 195       guint16 version_3_length;
 196       guint32 cist_internal_root_path_cost;
 197       guint8 mst_config_format_selector;
 198       guint16 cist_bridge_identifier_bridge_priority;
 199       const guint8  *cist_bridge_identifier_mac;
 200       gchar   *cist_bridge_identifier_mac_str;
 201       const guint8 *mst_config_name;
 202       guint16 mst_config_revision_level;
 203       guint8 cist_remaining_hops, msti_remaining_hops;
 204       guint32 msti_internal_root_path_cost;
 205       guint32 msti_regional_root_mstid, msti_regional_root_priority;
 206       const guint8  *msti_regional_root_mac;
 207       gchar   *msti_regional_root_mac_str;
 208       guint8 msti_bridge_identifier_priority, msti_port_identifier_priority;
 209       int       length, offset, msti;
 210
 211       proto_tree *bpdu_tree;
 212       proto_tree *mstp_tree, *msti_tree;
 213       proto_item *bpdu_item;
 214       proto_item *mstp_item, *msti_item;
 215       proto_tree *flags_tree;
 216       proto_item *flags_item;
 217       guint8    rstp_bpdu, mstp_bpdu=0;
 218       const char *sep;
 219
 220       /* GARP application frames require special interpretation of the
 221          destination address field; otherwise, they will be mistaken as
 222          BPDU frames.
 223          Fortunately, they can be recognized by checking the first 6 octets
 224          of the destination address, which are in the range from
 225          01-80-C2-00-00-20 to 01-80-C2-00-00-2F.
 226
 227          Yes - we *do* need to check the destination address type;
 228          on Linux cooked captures, there *is* no destination address,
 229          so it's AT_NONE. */
 230       if (pinfo->dl_dst.type == AT_ETHER &&
 231           pinfo->dl_dst.data[0] == 0x01 && pinfo->dl_dst.data[1] == 0x80 &&
 232           pinfo->dl_dst.data[2] == 0xC2 && pinfo->dl_dst.data[3] == 0x00 &&
 233           pinfo->dl_dst.data[4] == 0x00 && ((pinfo->dl_dst.data[5] & 0xF0) == 0x20)) {
 234
 235             protocol_identifier = tvb_get_ntohs(tvb, BPDU_IDENTIFIER);
 236
 237             switch (pinfo->dl_dst.data[5]) {
 238
 239             case 0x20:
 240                    /* for GMRP */
 241                   call_dissector(gmrp_handle, tvb, pinfo, tree);
 242                   return;
 243
 244             case 0x21:
 245                   /* for GVRP */
 246                   call_dissector(gvrp_handle, tvb, pinfo, tree);
 247                   return;
 248             }
 249
 250             pinfo->current_proto = "GARP";
 251
 252             if (check_col(pinfo->cinfo, COL_PROTOCOL)) {
 253                     col_set_str(pinfo->cinfo, COL_PROTOCOL, "GARP");
 254                     /* Generic Attribute Registration Protocol */
 255             }
 256
 257             if (check_col(pinfo->cinfo, COL_INFO)) {
 258                     col_add_fstr(pinfo->cinfo, COL_INFO,
 259                         "Unknown GARP application (0x%02X)",
 260                         pinfo->dl_dst.data[5]);
 261             }
 262
 263             return;
 264       }
 265
 266       if (check_col(pinfo->cinfo, COL_PROTOCOL)) {
 267             col_set_str(pinfo->cinfo, COL_PROTOCOL, "STP"); /* Spanning Tree Protocol */
 268       }
 269       if (check_col(pinfo->cinfo, COL_INFO)) {
 270             col_clear(pinfo->cinfo, COL_INFO);
 271       }
 272
 273       bpdu_type = tvb_get_guint8(tvb, BPDU_TYPE);
 274
 275       protocol_version_identifier = tvb_get_guint8(tvb, BPDU_VERSION_IDENTIFIER);
 276
 277       switch (bpdu_type) {
 278
 279       case BPDU_TYPE_CONF:
 280       case BPDU_TYPE_RST:
 281             flags = tvb_get_guint8(tvb, BPDU_FLAGS);
 282             root_identifier_bridge_priority = tvb_get_ntohs(tvb,BPDU_ROOT_IDENTIFIER);
 283             root_identifier_mac = tvb_get_ptr(tvb, BPDU_ROOT_IDENTIFIER + 2, 6);
 284             root_identifier_mac_str = ether_to_str(root_identifier_mac);
 285             root_path_cost = tvb_get_ntohl(tvb, BPDU_ROOT_PATH_COST);
 286             port_identifier = tvb_get_ntohs(tvb, BPDU_PORT_IDENTIFIER);
 287             break;
 288
 289       default:
 290             /* Squelch GCC complaints. */
 291             flags = 0;
 292             root_identifier_bridge_priority = 0;
 293             root_identifier_mac = NULL;
 294             root_identifier_mac_str = NULL;
 295             root_path_cost = 0;
 296             port_identifier = 0;
 297             break;
 298       }
 299
 300       if (check_col(pinfo->cinfo, COL_INFO)) {
 301             switch (bpdu_type) {
 302
 303             case BPDU_TYPE_CONF:
 304                   col_add_fstr(pinfo->cinfo, COL_INFO, "Conf. %sRoot = %d/%s  Cost = %d  Port = 0x%04x",
 305                                flags & 0x1 ? "TC + " : "",
 306                                root_identifier_bridge_priority, root_identifier_mac_str, root_path_cost,
 307                                port_identifier);
 308                   break;
 309
 310             case BPDU_TYPE_TOPOLOGY_CHANGE:
 311                   col_add_fstr(pinfo->cinfo, COL_INFO, "Topology Change Notification");
 312                   break;
 313
 314             case BPDU_TYPE_RST:
 315                   col_add_fstr(pinfo->cinfo, COL_INFO, "%cST. %sRoot = %d/%s  Cost = %d  Port = 0x%04x",
 316                                protocol_version_identifier == 3 ? 'M':'R',
 317                                flags & 0x1 ? "TC + " : "",
 318                                root_identifier_bridge_priority, root_identifier_mac_str, root_path_cost,
 319                                port_identifier);
 320                   break;
 321
 322             default:
 323                   col_add_fstr(pinfo->cinfo, COL_INFO, "Unknown BPDU type (%u)",
 324                                bpdu_type);
 325                   break;
 326             }
 327       }
 328
 329       switch (bpdu_type) {
 330
 331       case BPDU_TYPE_CONF:
 332         set_actual_length(tvb, CONF_BPDU_SIZE);
 333         break;
 334
 335       case BPDU_TYPE_TOPOLOGY_CHANGE:
 336         set_actual_length(tvb, TC_BPDU_SIZE);
 337         break;
 338
 339       case BPDU_TYPE_RST:
 340         if (protocol_version_identifier == 3) {
 341             version_3_length = tvb_get_ntohs(tvb, BPDU_VERSION_3_LENGTH);
 342             set_actual_length(tvb, RST_BPDU_SIZE + 2 + version_3_length);
 343         } else
 344             set_actual_length(tvb, RST_BPDU_SIZE);
 345         break;
 346       }
 347
 348       if (tree) {
 349             bpdu_item = proto_tree_add_protocol_format(tree, proto_bpdu, tvb,
 350                                 0, -1, "Spanning Tree Protocol");
 351             bpdu_tree = proto_item_add_subtree(bpdu_item, ett_bpdu);
 352
 353             protocol_identifier = tvb_get_ntohs(tvb, BPDU_IDENTIFIER);
 354             proto_tree_add_uint(bpdu_tree, hf_bpdu_proto_id, tvb,
 355                                 BPDU_IDENTIFIER, 2, protocol_identifier);
 356
 357             proto_tree_add_uint(bpdu_tree, hf_bpdu_version_id, tvb,
 358                                 BPDU_VERSION_IDENTIFIER, 1,
 359                                 protocol_version_identifier);
 360             switch (protocol_version_identifier) {
 361               case 0:
 362                 break;
 363               case 2:
 364               case 3:
 365                 break;
 366               default:
 367                   proto_tree_add_text(bpdu_tree, tvb, BPDU_VERSION_IDENTIFIER, 1,
 368                   "   (Warning: this version of Ethereal only knows about versions 0, 2 & 3)");
 369                 break;
 370             }
 371             proto_tree_add_uint(bpdu_tree, hf_bpdu_type, tvb,
 372                                        BPDU_TYPE, 1,
 373                                        bpdu_type);
 374
 375             if (bpdu_type != BPDU_TYPE_CONF && bpdu_type != BPDU_TYPE_RST) {
 376               call_dissector(data_handle,
 377                              tvb_new_subset(tvb, BPDU_TYPE + 1, -1, -1),
 378                              pinfo, tree);
 379               return;
 380             }
 381
 382             rstp_bpdu = (bpdu_type == BPDU_TYPE_RST);
 383             if (rstp_bpdu) mstp_bpdu = (protocol_version_identifier == 3);
 384
 385             bridge_identifier_bridge_priority = tvb_get_ntohs(tvb, BPDU_BRIDGE_IDENTIFIER);
 386             bridge_identifier_mac = tvb_get_ptr(tvb, BPDU_BRIDGE_IDENTIFIER + 2, 6);
 387             bridge_identifier_mac_str = ether_to_str(bridge_identifier_mac);
 388
 389             flags_item = proto_tree_add_uint(bpdu_tree, hf_bpdu_flags, tvb,
 390                                 BPDU_FLAGS, 1, flags);
 391             flags_tree = proto_item_add_subtree(flags_item, ett_bpdu_flags);
 392             sep = initial_sep;
 393             APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_TCACK, flags_item,
 394                                 "%sTopology Change Acknowledgment");
 395             proto_tree_add_boolean(flags_tree, hf_bpdu_flags_tcack, tvb,
 396                                 BPDU_FLAGS, 1, flags);
 397             if (rstp_bpdu) {
 398               APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_AGREEMENT, flags_item,
 399                                   "%sAgreement");
 400               proto_tree_add_boolean(flags_tree, hf_bpdu_flags_agreement, tvb,
 401                                   BPDU_FLAGS, 1, flags);
 402               APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_FORWARDING, flags_item,
 403                                   "%sForwarding");
 404               proto_tree_add_boolean(flags_tree, hf_bpdu_flags_forwarding, tvb,
 405                                   BPDU_FLAGS, 1, flags);
 406               APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_LEARNING, flags_item,
 407                                   "%sLearning");
 408               proto_tree_add_boolean(flags_tree, hf_bpdu_flags_learning, tvb,
 409                                   BPDU_FLAGS, 1, flags);
 410               if (flags_item) {
 411                 guint8 port_role;
 412
 413                 port_role = (flags & BPDU_FLAGS_PORT_ROLE_MASK) >> BPDU_FLAGS_PORT_ROLE_SHIFT;
 414                 proto_item_append_text(flags_item, "%sPort Role: %s", sep,
 415                                        val_to_str(port_role, role_vals,
 416                                                   "Unknown (%u)"));
 417               }
 418               sep = cont_sep;
 419               proto_tree_add_uint(flags_tree, hf_bpdu_flags_port_role, tvb,
 420                                   BPDU_FLAGS, 1, flags);
 421               APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_PROPOSAL, flags_item,
 422                                   "%sProposal");
 423               proto_tree_add_boolean(flags_tree, hf_bpdu_flags_proposal, tvb,
 424                                   BPDU_FLAGS, 1, flags);
 425             }
 426             APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_TC, flags_item,
 427                                 "%sTopology Change");
 428             proto_tree_add_boolean(flags_tree, hf_bpdu_flags_tc, tvb,
 429                                 BPDU_FLAGS, 1, flags);
 430             if (sep != initial_sep) {
 431               /* We put something in; put in the terminating ")" */
 432               proto_item_append_text(flags_item, ")");
 433             }
 434
 435             proto_tree_add_ether_hidden(bpdu_tree, hf_bpdu_root_mac, tvb,
 436                                        BPDU_ROOT_IDENTIFIER + 2, 6,
 437                                        root_identifier_mac);
 438             proto_tree_add_text(bpdu_tree, tvb,
 439                                 BPDU_ROOT_IDENTIFIER, 8,
 440                                 "Root Identifier: %d / %s",
 441                                 root_identifier_bridge_priority,
 442                                 root_identifier_mac_str);
 443             proto_tree_add_uint(bpdu_tree, hf_bpdu_root_cost, tvb,
 444                                 BPDU_ROOT_PATH_COST, 4,
 445                                 root_path_cost);
 446             proto_tree_add_text(bpdu_tree, tvb,
 447                                 BPDU_BRIDGE_IDENTIFIER, 8,
 448                                 "Bridge Identifier: %d / %s",
 449                                 bridge_identifier_bridge_priority,
 450                                 bridge_identifier_mac_str);
 451             proto_tree_add_ether_hidden(bpdu_tree, hf_bpdu_bridge_mac, tvb,
 452                                        BPDU_BRIDGE_IDENTIFIER + 2, 6,
 453                                        bridge_identifier_mac);
 454             proto_tree_add_uint(bpdu_tree, hf_bpdu_port_id, tvb,
 455                                 BPDU_PORT_IDENTIFIER, 2,
 456                                 port_identifier);
 457             message_age = tvb_get_ntohs(tvb, BPDU_MESSAGE_AGE) / 256.0;
 458             proto_tree_add_double(bpdu_tree, hf_bpdu_msg_age, tvb,
 459                                 BPDU_MESSAGE_AGE, 2,
 460                                 message_age);
 461             max_age = tvb_get_ntohs(tvb, BPDU_MAX_AGE) / 256.0;
 462             proto_tree_add_double(bpdu_tree, hf_bpdu_max_age, tvb,
 463                                 BPDU_MAX_AGE, 2,
 464                                 max_age);
 465             hello_time = tvb_get_ntohs(tvb, BPDU_HELLO_TIME) / 256.0;
 466             proto_tree_add_double(bpdu_tree, hf_bpdu_hello_time, tvb,
 467                                 BPDU_HELLO_TIME, 2,
 468                                 hello_time);
 469             forward_delay = tvb_get_ntohs(tvb, BPDU_FORWARD_DELAY) / 256.0;
 470             proto_tree_add_double(bpdu_tree, hf_bpdu_forward_delay, tvb,
 471                                 BPDU_FORWARD_DELAY, 2,
 472                                 forward_delay);
 473             if (rstp_bpdu) {
 474               proto_tree_add_item(bpdu_tree, hf_bpdu_version_1_length, tvb,
 475                                 BPDU_VERSION_1_LENGTH, 1, FALSE);
 476             }
 477             if (mstp_bpdu) {
 478                 version_3_length = tvb_get_ntohs(tvb, BPDU_VERSION_3_LENGTH);
 479
 480                 mstp_item = proto_tree_add_uint(bpdu_tree, hf_bpdu_version_3_length, tvb,
 481                         BPDU_VERSION_3_LENGTH, 2, version_3_length);
 482                 mstp_tree = proto_item_add_subtree(mstp_item, ett_mstp);
 483
 484
 485                 mst_config_format_selector = tvb_get_guint8(tvb, BPDU_MST_CONFIG_FORMAT_SELECTOR);
 486                 proto_tree_add_uint(mstp_tree, hf_bpdu_mst_config_format_selector, tvb,
 487                         BPDU_MST_CONFIG_FORMAT_SELECTOR, 1, mst_config_format_selector);
 488                 mst_config_name =  tvb_get_ptr (tvb, BPDU_MST_CONFIG_NAME, 32);
 489                 proto_tree_add_string(mstp_tree, hf_bpdu_mst_config_name, tvb, BPDU_MST_CONFIG_NAME, 32, mst_config_name);
 490
 491                 mst_config_revision_level = tvb_get_ntohs(tvb, BPDU_MST_CONFIG_REVISION_LEVEL);
 492                 proto_tree_add_uint(mstp_tree, hf_bpdu_mst_config_revision_level, tvb,
 493                         BPDU_MST_CONFIG_REVISION_LEVEL, 2, mst_config_revision_level);
 494                 proto_tree_add_bytes(mstp_tree, hf_bpdu_mst_config_digest, tvb,
 495                         BPDU_MST_CONFIG_DIGEST, 16, tvb_get_ptr(tvb, BPDU_MST_CONFIG_DIGEST, 16));
 496
 497                 cist_internal_root_path_cost = tvb_get_ntohl(tvb, BPDU_CIST_INTERNAL_ROOT_PATH_COST);
 498                 proto_tree_add_uint(mstp_tree, hf_bpdu_cist_internal_root_path_cost, tvb,
 499                         BPDU_CIST_INTERNAL_ROOT_PATH_COST, 4, cist_internal_root_path_cost);
 500
 501                 cist_bridge_identifier_bridge_priority = tvb_get_ntohs(tvb,BPDU_CIST_BRIDGE_IDENTIFIER);
 502                 cist_bridge_identifier_mac = tvb_get_ptr(tvb, BPDU_CIST_BRIDGE_IDENTIFIER + 2, 6);
 503                 cist_bridge_identifier_mac_str = ether_to_str(cist_bridge_identifier_mac);
 504                 proto_tree_add_text(mstp_tree, tvb, BPDU_CIST_BRIDGE_IDENTIFIER, 8,
 505                                 "CIST Bridge Identifier: %d / %s",
 506                                 cist_bridge_identifier_bridge_priority,
 507                                 cist_bridge_identifier_mac_str);
 508                 proto_tree_add_ether_hidden(mstp_tree, hf_bpdu_cist_bridge_identifier_mac, tvb,
 509                                        BPDU_CIST_BRIDGE_IDENTIFIER + 2, 6,
 510                                        cist_bridge_identifier_mac);
 511
 512                 cist_remaining_hops = tvb_get_guint8(tvb, BPDU_CIST_REMAINING_HOPS);
 513                 proto_tree_add_uint(mstp_tree, hf_bpdu_cist_remaining_hops, tvb,
 514                         BPDU_CIST_REMAINING_HOPS, 1, cist_remaining_hops);
 515
 516         /* MSTI messages */
 517                 length = version_3_length - VERSION_3_STATIC_LENGTH;
 518                 offset = BPDU_MSTI;
 519                 msti = 1;
 520                 while (length >= MSTI_MESSAGE_SIZE) {
 521                     msti_regional_root_mstid = tvb_get_guint8(tvb,  offset+ MSTI_REGIONAL_ROOT);
 522                     msti_regional_root_priority = (msti_regional_root_mstid &0xf0) << 8;
 523                     msti_regional_root_mstid = ((msti_regional_root_mstid & 0x0f) << 8) +
 524                                 tvb_get_guint8(tvb,  offset+ MSTI_REGIONAL_ROOT+1);;
 525                     msti_regional_root_mac = tvb_get_ptr(tvb, offset+ MSTI_REGIONAL_ROOT + 2, 6);
 526                     msti_regional_root_mac_str = ether_to_str(msti_regional_root_mac);
 527
 528                     msti_item = proto_tree_add_text(mstp_tree, tvb, offset, 16,
 529                         "MSTID %d, Regional Root Identifier %d / %s",
 530                         msti_regional_root_mstid, msti_regional_root_priority,
 531                         msti_regional_root_mac_str);
 532                     msti_tree = proto_item_add_subtree(msti_item, ett_msti);
 533
 534                     /* flags */
 535                     flags_item = proto_tree_add_uint(msti_tree, hf_bpdu_msti_flags, tvb,
 536                         offset+MSTI_FLAGS, 1, flags);
 537
 538                     sep = initial_sep;
 539                     APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_TCACK, flags_item, "%sMaster");
 540                     APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_AGREEMENT, flags_item, "%sAgreement");
 541                     APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_FORWARDING, flags_item, "%sForwarding");
 542                     APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_LEARNING, flags_item, "%sLearning");
 543                     if (flags_item) {
 544                         guint8 port_role;
 545                         port_role = (flags & BPDU_FLAGS_PORT_ROLE_MASK) >> BPDU_FLAGS_PORT_ROLE_SHIFT;
 546                         proto_item_append_text(flags_item, "%sPort Role: %s", sep,
 547                                        val_to_str(port_role, role_vals, "Unknown (%u)"));
 548                     }
 549                     sep = cont_sep;
 550                     APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_PROPOSAL, flags_item, "%sProposal");
 551                     APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_TC, flags_item, "%sTopology Change");
 552                     if (sep != initial_sep) {         /* We put something in; put in the terminating ")" */
 553                         proto_item_append_text(flags_item, ")");
 554                     }
 555
 556                     /* pri, MSTID, Regional root */
 557                     proto_tree_add_ether_hidden(msti_tree, hf_bpdu_msti_regional_root_mac, tvb,
 558                                        offset + MSTI_REGIONAL_ROOT + 2, 6,
 559                                        msti_regional_root_mac);
 560                     proto_tree_add_text(msti_tree, tvb, offset + MSTI_REGIONAL_ROOT, 8,
 561                                 "MSTID %d, priority %d Root Identifier %s",
 562                                 msti_regional_root_mstid, msti_regional_root_priority,
 563                                 msti_regional_root_mac_str);
 564
 565
 566                     msti_internal_root_path_cost = tvb_get_ntohs(tvb, offset+MSTI_INTERNAL_ROOT_PATH_COST);
 567                     proto_tree_add_uint(msti_tree, hf_bpdu_msti_internal_root_path_cost, tvb,
 568                         offset+MSTI_INTERNAL_ROOT_PATH_COST, 4, msti_internal_root_path_cost);
 569
 570                     msti_bridge_identifier_priority = tvb_get_guint8(tvb, offset+MSTI_BRIDGE_IDENTIFIER_PRIORITY) >> 4;
 571                     msti_port_identifier_priority = tvb_get_guint8(tvb, offset+MSTI_PORT_IDENTIFIER_PRIORITY) >> 4;
 572
 573                     proto_tree_add_uint(msti_tree, hf_bpdu_msti_bridge_identifier_priority, tvb,
 574                         offset+MSTI_BRIDGE_IDENTIFIER_PRIORITY, 1, msti_bridge_identifier_priority);
 575                     proto_tree_add_uint(msti_tree, hf_bpdu_msti_port_identifier_priority, tvb,
 576                         offset+MSTI_PORT_IDENTIFIER_PRIORITY, 1, msti_port_identifier_priority);
 577
 578                     msti_remaining_hops = tvb_get_guint8(tvb, offset+MSTI_REMAINING_HOPS);
 579                     proto_tree_add_uint(msti_tree, hf_bpdu_msti_remaining_hops, tvb,
 580                         offset + MSTI_REMAINING_HOPS, 1, msti_remaining_hops);
 581
 582                     length -= MSTI_MESSAGE_SIZE;
 583                     offset += MSTI_MESSAGE_SIZE;
 584                     msti++;
 585                 }
 586
 587             }
 588       }
 589 }
 590
 591 static const true_false_string yesno = {
 592         "Yes",
 593         "No"
 594 };
 595
 596 void
 597 proto_register_bpdu(void)
 598 {
 599
 600   static hf_register_info hf[] = {
 601     { &hf_bpdu_proto_id,
 602       { "Protocol Identifier",          "stp.protocol",
 603         FT_UINT16,      BASE_HEX,       VALS(&protocol_id_vals), 0x0,
 604         "", HFILL }},
 605     { &hf_bpdu_version_id,
 606       { "Protocol Version Identifier",  "stp.version",
 607         FT_UINT8,       BASE_DEC,       VALS(&version_id_vals), 0x0,
 608         "", HFILL }},
 609     { &hf_bpdu_type,
 610       { "BPDU Type",                    "stp.type",
 611         FT_UINT8,       BASE_HEX,       VALS(&bpdu_type_vals),  0x0,
 612         "", HFILL }},
 613     { &hf_bpdu_flags,
 614       { "BPDU flags",                   "stp.flags",
 615         FT_UINT8,       BASE_HEX,       NULL,   0x0,
 616         "", HFILL }},
 617     { &hf_bpdu_flags_tcack,
 618       { "Topology Change Acknowledgment",  "stp.flags.tcack",
 619         FT_BOOLEAN,     8,              TFS(&yesno),    BPDU_FLAGS_TCACK,
 620         "", HFILL }},
 621     { &hf_bpdu_flags_agreement,
 622       { "Agreement",                    "stp.flags.agreement",
 623         FT_BOOLEAN,     8,              TFS(&yesno),    BPDU_FLAGS_AGREEMENT,
 624         "", HFILL }},
 625     { &hf_bpdu_flags_forwarding,
 626       { "Forwarding",                   "stp.flags.forwarding",
 627         FT_BOOLEAN,     8,              TFS(&yesno),    BPDU_FLAGS_FORWARDING,
 628         "", HFILL }},
 629     { &hf_bpdu_flags_learning,
 630       { "Learning",                     "stp.flags.learning",
 631         FT_BOOLEAN,     8,              TFS(&yesno),    BPDU_FLAGS_LEARNING,
 632         "", HFILL }},
 633     { &hf_bpdu_flags_port_role,
 634       { "Port Role",                    "stp.flags.port_role",
 635         FT_UINT8,       BASE_DEC,       VALS(role_vals),        BPDU_FLAGS_PORT_ROLE_MASK,
 636         "", HFILL }},
 637     { &hf_bpdu_flags_proposal,
 638       { "Proposal",                     "stp.flags.proposal",
 639         FT_BOOLEAN,     8,              TFS(&yesno),    BPDU_FLAGS_PROPOSAL,
 640         "", HFILL }},
 641     { &hf_bpdu_flags_tc,
 642       { "Topology Change",              "stp.flags.tc",
 643         FT_BOOLEAN,     8,              TFS(&yesno),    BPDU_FLAGS_TC,
 644         "", HFILL }},
 645     { &hf_bpdu_root_mac,
 646       { "Root Identifier",              "stp.root.hw",
 647         FT_ETHER,       BASE_NONE,      NULL,   0x0,
 648         "", HFILL }},
 649     { &hf_bpdu_root_cost,
 650       { "Root Path Cost",               "stp.root.cost",
 651         FT_UINT32,      BASE_DEC,       NULL,   0x0,
 652         "", HFILL }},
 653     { &hf_bpdu_bridge_mac,
 654       { "Bridge Identifier",            "stp.bridge.hw",
 655         FT_ETHER,       BASE_NONE,      NULL,   0x0,
 656         "", HFILL }},
 657     { &hf_bpdu_port_id,
 658       { "Port identifier",              "stp.port",
 659         FT_UINT16,      BASE_HEX,       NULL,   0x0,
 660         "", HFILL }},
 661     { &hf_bpdu_msg_age,
 662       { "Message Age",                  "stp.msg_age",
 663         FT_DOUBLE,      BASE_NONE,      NULL,   0x0,
 664         "", HFILL }},
 665     { &hf_bpdu_max_age,
 666       { "Max Age",                      "stp.max_age",
 667         FT_DOUBLE,      BASE_NONE,      NULL,   0x0,
 668         "", HFILL }},
 669     { &hf_bpdu_hello_time,
 670       { "Hello Time",                   "stp.hello",
 671         FT_DOUBLE,      BASE_NONE,      NULL,   0x0,
 672         "", HFILL }},
 673     { &hf_bpdu_forward_delay,
 674       { "Forward Delay",                "stp.forward",
 675         FT_DOUBLE,      BASE_NONE,      NULL,   0x0,
 676         "", HFILL }},
 677     { &hf_bpdu_version_1_length,
 678       { "Version 1 Length",             "stp.version_1_length",
 679         FT_UINT8,       BASE_DEC,       NULL,   0x0,
 680         "", HFILL }},
 681     { &hf_bpdu_version_3_length,
 682       { "MST Extension, Length",                "mstp.version_3_length",
 683         FT_UINT16,      BASE_DEC,       NULL,   0x0,
 684         "", HFILL }},
 685     { &hf_bpdu_mst_config_format_selector,
 686       { "MST Config ID format selector",                "mstp.config_format_selector",
 687         FT_UINT8,       BASE_DEC,       NULL,   0x0,
 688         "", HFILL }},
 689     { &hf_bpdu_mst_config_name,
 690       { "MST Config name",              "mstp.config_name",
 691         FT_STRING,      BASE_DEC,       NULL,   0x0,
 692         "", HFILL }},
 693     { &hf_bpdu_mst_config_revision_level,
 694       { "MST Config revision",          "mstp.config_revision_level",
 695         FT_UINT16,      BASE_DEC,       NULL,   0x0,
 696         "", HFILL }},
 697     { &hf_bpdu_mst_config_digest,
 698       { "MST Config digest",            "mstp.config_digest",
 699         FT_BYTES,       BASE_DEC,       NULL,   0x0,
 700         "", HFILL }},
 701     { &hf_bpdu_cist_internal_root_path_cost,
 702       { "CIST Internal Root Path Cost",         "mstp.cist_internal_root_path_cost",
 703         FT_UINT32,      BASE_DEC,       NULL,   0x0,
 704         "", HFILL }},
 705     { &hf_bpdu_cist_bridge_identifier_mac,
 706       { "CIST Bridge Identifier",               "mstp.cist_bridge.hw",
 707         FT_ETHER,       BASE_DEC,       NULL,   0x0,
 708         "", HFILL }},
 709     { &hf_bpdu_cist_remaining_hops,
 710       { "CIST Remaining hops",          "mstp.cist_remaining_hops",
 711         FT_UINT8,       BASE_DEC,       NULL,   0x0,
 712         "", HFILL }},
 713     { &hf_bpdu_msti_flags,
 714       { "MSTI flags",                   "mstp.msti.flags",
 715         FT_UINT8,       BASE_HEX,       NULL,   0x0,
 716         "", HFILL }},
 717     { &hf_bpdu_msti_regional_root_mac,
 718       { "Regional Root",                "mstp.msti.root.hw",
 719         FT_ETHER,       BASE_DEC,       NULL,   0x0,
 720         "", HFILL }},
 721     { &hf_bpdu_msti_internal_root_path_cost,
 722       { "Internal root path cost",              "mstp.msti.root_cost",
 723         FT_UINT32,      BASE_DEC,       NULL,   0x0,
 724         "", HFILL }},
 725     { &hf_bpdu_msti_bridge_identifier_priority,
 726       { "Bridge Identifier Priority",           "mstp.msti.bridge_priority",
 727         FT_UINT8,       BASE_DEC,       NULL,   0x0,
 728         "", HFILL }},
 729     { &hf_bpdu_msti_port_identifier_priority,
 730       { "Port identifier prority",              "mstp.msti.port_priority",
 731         FT_UINT8,       BASE_DEC,       NULL,   0x0,
 732         "", HFILL }},
 733     { &hf_bpdu_msti_remaining_hops,
 734       { "Remaining hops",               "mstp.msti.remaining_hops",
 735         FT_UINT8,       BASE_DEC,       NULL,   0x0,
 736         "", HFILL }},
 737
 738   };
 739   static gint *ett[] = {
 740     &ett_bpdu,
 741     &ett_bpdu_flags,
 742     &ett_mstp,
 743     &ett_msti
 744   };
 745
 746   proto_bpdu = proto_register_protocol("Spanning Tree Protocol", "STP", "stp");
 747   proto_register_field_array(proto_bpdu, hf, array_length(hf));
 748   proto_register_subtree_array(ett, array_length(ett));
 749
 750   register_dissector("bpdu", dissect_bpdu, proto_bpdu);
 751 }
 752
 753 void
 754 proto_reg_handoff_bpdu(void)
 755 {
 756   dissector_handle_t bpdu_handle;
 757
 758   /*
 759    * Get handle for the GVRP dissector.
 760    */
 761   gvrp_handle = find_dissector("gvrp");
 762
 763   /*
 764    * Get handle for the GMRP dissector.
 765    */
 766   gmrp_handle = find_dissector("gmrp");
 767   data_handle = find_dissector("data");
 768
 769   bpdu_handle = find_dissector("bpdu");
 770   dissector_add("llc.dsap", SAP_BPDU, bpdu_handle);
 771   dissector_add("ppp.protocol", PPP_BPDU, bpdu_handle);
 772   dissector_add("chdlctype", CHDLCTYPE_BPDU, bpdu_handle);
 773 }