packet-bpdu.c

   1 /* packet-bpdu.c
   2  * Routines for BPDU (Spanning Tree Protocol) disassembly
   3  *
   4  * $Id$
   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 66
  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             /*
 343              * XXX - there appears to be an ambiguity in the 802.1s spec.
 344              * In 14.6.q and Figure 14-1, the "Version 3 Length" field
 345              * "is the number of octets taken by the parameters that
 346              * follow in the BPDU", but item 14.4.e.3 speaks of "a
 347              * Version 3 length representing an integral number, from 0
 348              * to 64 inclusive, of MSTI Configuration Messages".
 349              *
 350              * According to mail from a member of the stds-802-1@ieee.org
 351              * list, item 14.4.e.3 is just saying that the length must
 352              * not have a value that implies that there's a partial
 353              * MSTI message in the packet, and that it's in units of
 354              * bytes, not messages.
 355              *
 356              * However, it appears that Cisco's C3550 software
 357              * (C3550-I5Q3L2-M, Version 12.1(12c)EA1) might be sending out
 358              * lengths in units of messages.
 359              *
 360              * So if the length is too short, we assume it's because it's
 361              * in units of messages, not bytes.
 362              */
 363             if (version_3_length < VERSION_3_STATIC_LENGTH - 2) {
 364                 set_actual_length(tvb, RST_BPDU_SIZE +
 365                                   VERSION_3_STATIC_LENGTH +
 366                                   version_3_length * MSTI_MESSAGE_SIZE);
 367             } else
 368                 set_actual_length(tvb, RST_BPDU_SIZE + 2 + version_3_length);
 369         } else
 370             set_actual_length(tvb, RST_BPDU_SIZE);
 371         break;
 372       }
 373
 374       if (tree) {
 375             bpdu_item = proto_tree_add_protocol_format(tree, proto_bpdu, tvb,
 376                                 0, -1, "Spanning Tree Protocol");
 377             bpdu_tree = proto_item_add_subtree(bpdu_item, ett_bpdu);
 378
 379             protocol_identifier = tvb_get_ntohs(tvb, BPDU_IDENTIFIER);
 380             proto_tree_add_uint(bpdu_tree, hf_bpdu_proto_id, tvb,
 381                                 BPDU_IDENTIFIER, 2, protocol_identifier);
 382
 383             proto_tree_add_uint(bpdu_tree, hf_bpdu_version_id, tvb,
 384                                 BPDU_VERSION_IDENTIFIER, 1,
 385                                 protocol_version_identifier);
 386             switch (protocol_version_identifier) {
 387               case 0:
 388                 break;
 389               case 2:
 390               case 3:
 391                 break;
 392               default:
 393                   proto_tree_add_text(bpdu_tree, tvb, BPDU_VERSION_IDENTIFIER, 1,
 394                   "   (Warning: this version of Ethereal only knows about versions 0, 2 & 3)");
 395                 break;
 396             }
 397             proto_tree_add_uint(bpdu_tree, hf_bpdu_type, tvb,
 398                                        BPDU_TYPE, 1,
 399                                        bpdu_type);
 400
 401             if (bpdu_type != BPDU_TYPE_CONF && bpdu_type != BPDU_TYPE_RST) {
 402               call_dissector(data_handle,
 403                              tvb_new_subset(tvb, BPDU_TYPE + 1, -1, -1),
 404                              pinfo, tree);
 405               return;
 406             }
 407
 408             rstp_bpdu = (bpdu_type == BPDU_TYPE_RST);
 409             if (rstp_bpdu) mstp_bpdu = (protocol_version_identifier == 3);
 410
 411             bridge_identifier_bridge_priority = tvb_get_ntohs(tvb, BPDU_BRIDGE_IDENTIFIER);
 412             bridge_identifier_mac = tvb_get_ptr(tvb, BPDU_BRIDGE_IDENTIFIER + 2, 6);
 413             bridge_identifier_mac_str = ether_to_str(bridge_identifier_mac);
 414
 415             flags_item = proto_tree_add_uint(bpdu_tree, hf_bpdu_flags, tvb,
 416                                 BPDU_FLAGS, 1, flags);
 417             flags_tree = proto_item_add_subtree(flags_item, ett_bpdu_flags);
 418             sep = initial_sep;
 419             APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_TCACK, flags_item,
 420                                 "%sTopology Change Acknowledgment");
 421             proto_tree_add_boolean(flags_tree, hf_bpdu_flags_tcack, tvb,
 422                                 BPDU_FLAGS, 1, flags);
 423             if (rstp_bpdu) {
 424               APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_AGREEMENT, flags_item,
 425                                   "%sAgreement");
 426               proto_tree_add_boolean(flags_tree, hf_bpdu_flags_agreement, tvb,
 427                                   BPDU_FLAGS, 1, flags);
 428               APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_FORWARDING, flags_item,
 429                                   "%sForwarding");
 430               proto_tree_add_boolean(flags_tree, hf_bpdu_flags_forwarding, tvb,
 431                                   BPDU_FLAGS, 1, flags);
 432               APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_LEARNING, flags_item,
 433                                   "%sLearning");
 434               proto_tree_add_boolean(flags_tree, hf_bpdu_flags_learning, tvb,
 435                                   BPDU_FLAGS, 1, flags);
 436               if (flags_item) {
 437                 guint8 port_role;
 438
 439                 port_role = (flags & BPDU_FLAGS_PORT_ROLE_MASK) >> BPDU_FLAGS_PORT_ROLE_SHIFT;
 440                 proto_item_append_text(flags_item, "%sPort Role: %s", sep,
 441                                        val_to_str(port_role, role_vals,
 442                                                   "Unknown (%u)"));
 443               }
 444               sep = cont_sep;
 445               proto_tree_add_uint(flags_tree, hf_bpdu_flags_port_role, tvb,
 446                                   BPDU_FLAGS, 1, flags);
 447               APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_PROPOSAL, flags_item,
 448                                   "%sProposal");
 449               proto_tree_add_boolean(flags_tree, hf_bpdu_flags_proposal, tvb,
 450                                   BPDU_FLAGS, 1, flags);
 451             }
 452             APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_TC, flags_item,
 453                                 "%sTopology Change");
 454             proto_tree_add_boolean(flags_tree, hf_bpdu_flags_tc, tvb,
 455                                 BPDU_FLAGS, 1, flags);
 456             if (sep != initial_sep) {
 457               /* We put something in; put in the terminating ")" */
 458               proto_item_append_text(flags_item, ")");
 459             }
 460
 461             proto_tree_add_ether_hidden(bpdu_tree, hf_bpdu_root_mac, tvb,
 462                                        BPDU_ROOT_IDENTIFIER + 2, 6,
 463                                        root_identifier_mac);
 464             proto_tree_add_text(bpdu_tree, tvb,
 465                                 BPDU_ROOT_IDENTIFIER, 8,
 466                                 "Root Identifier: %d / %s",
 467                                 root_identifier_bridge_priority,
 468                                 root_identifier_mac_str);
 469             proto_tree_add_uint(bpdu_tree, hf_bpdu_root_cost, tvb,
 470                                 BPDU_ROOT_PATH_COST, 4,
 471                                 root_path_cost);
 472             proto_tree_add_text(bpdu_tree, tvb,
 473                                 BPDU_BRIDGE_IDENTIFIER, 8,
 474                                 "Bridge Identifier: %d / %s",
 475                                 bridge_identifier_bridge_priority,
 476                                 bridge_identifier_mac_str);
 477             proto_tree_add_ether_hidden(bpdu_tree, hf_bpdu_bridge_mac, tvb,
 478                                        BPDU_BRIDGE_IDENTIFIER + 2, 6,
 479                                        bridge_identifier_mac);
 480             proto_tree_add_uint(bpdu_tree, hf_bpdu_port_id, tvb,
 481                                 BPDU_PORT_IDENTIFIER, 2,
 482                                 port_identifier);
 483             message_age = tvb_get_ntohs(tvb, BPDU_MESSAGE_AGE) / 256.0;
 484             proto_tree_add_double(bpdu_tree, hf_bpdu_msg_age, tvb,
 485                                 BPDU_MESSAGE_AGE, 2,
 486                                 message_age);
 487             max_age = tvb_get_ntohs(tvb, BPDU_MAX_AGE) / 256.0;
 488             proto_tree_add_double(bpdu_tree, hf_bpdu_max_age, tvb,
 489                                 BPDU_MAX_AGE, 2,
 490                                 max_age);
 491             hello_time = tvb_get_ntohs(tvb, BPDU_HELLO_TIME) / 256.0;
 492             proto_tree_add_double(bpdu_tree, hf_bpdu_hello_time, tvb,
 493                                 BPDU_HELLO_TIME, 2,
 494                                 hello_time);
 495             forward_delay = tvb_get_ntohs(tvb, BPDU_FORWARD_DELAY) / 256.0;
 496             proto_tree_add_double(bpdu_tree, hf_bpdu_forward_delay, tvb,
 497                                 BPDU_FORWARD_DELAY, 2,
 498                                 forward_delay);
 499             if (rstp_bpdu) {
 500               proto_tree_add_item(bpdu_tree, hf_bpdu_version_1_length, tvb,
 501                                 BPDU_VERSION_1_LENGTH, 1, FALSE);
 502             }
 503             if (mstp_bpdu) {
 504                 version_3_length = tvb_get_ntohs(tvb, BPDU_VERSION_3_LENGTH);
 505
 506                 mstp_item = proto_tree_add_uint(bpdu_tree, hf_bpdu_version_3_length, tvb,
 507                         BPDU_VERSION_3_LENGTH, 2, version_3_length);
 508                 /*
 509                  * XXX - see comment above about the interpretation of the
 510                  * "Version 3 Length" field not being clear.
 511                  */
 512                 if (version_3_length < VERSION_3_STATIC_LENGTH - 2) {
 513                     proto_item_append_text(mstp_item,
 514                                            " (Malformed: number of MSTI messages!!! Must be %u)",
 515                                            (VERSION_3_STATIC_LENGTH - 2 + version_3_length * MSTI_MESSAGE_SIZE));
 516                 } else {
 517                     proto_item_append_text(mstp_item,
 518                                            " (Number of MSTI messages: %u)",
 519                                            (version_3_length - (VERSION_3_STATIC_LENGTH - 2)) / MSTI_MESSAGE_SIZE);
 520                 }
 521                 mstp_tree = proto_item_add_subtree(mstp_item, ett_mstp);
 522
 523                 mst_config_format_selector = tvb_get_guint8(tvb, BPDU_MST_CONFIG_FORMAT_SELECTOR);
 524                 proto_tree_add_uint(mstp_tree, hf_bpdu_mst_config_format_selector, tvb,
 525                         BPDU_MST_CONFIG_FORMAT_SELECTOR, 1, mst_config_format_selector);
 526                 mst_config_name =  tvb_get_ptr (tvb, BPDU_MST_CONFIG_NAME, 32);
 527                 proto_tree_add_string(mstp_tree, hf_bpdu_mst_config_name, tvb, BPDU_MST_CONFIG_NAME, 32, mst_config_name);
 528
 529                 mst_config_revision_level = tvb_get_ntohs(tvb, BPDU_MST_CONFIG_REVISION_LEVEL);
 530                 proto_tree_add_uint(mstp_tree, hf_bpdu_mst_config_revision_level, tvb,
 531                         BPDU_MST_CONFIG_REVISION_LEVEL, 2, mst_config_revision_level);
 532                 proto_tree_add_bytes(mstp_tree, hf_bpdu_mst_config_digest, tvb,
 533                         BPDU_MST_CONFIG_DIGEST, 16, tvb_get_ptr(tvb, BPDU_MST_CONFIG_DIGEST, 16));
 534
 535                 cist_internal_root_path_cost = tvb_get_ntohl(tvb, BPDU_CIST_INTERNAL_ROOT_PATH_COST);
 536                 proto_tree_add_uint(mstp_tree, hf_bpdu_cist_internal_root_path_cost, tvb,
 537                         BPDU_CIST_INTERNAL_ROOT_PATH_COST, 4, cist_internal_root_path_cost);
 538
 539                 cist_bridge_identifier_bridge_priority = tvb_get_ntohs(tvb,BPDU_CIST_BRIDGE_IDENTIFIER);
 540                 cist_bridge_identifier_mac = tvb_get_ptr(tvb, BPDU_CIST_BRIDGE_IDENTIFIER + 2, 6);
 541                 cist_bridge_identifier_mac_str = ether_to_str(cist_bridge_identifier_mac);
 542                 proto_tree_add_text(mstp_tree, tvb, BPDU_CIST_BRIDGE_IDENTIFIER, 8,
 543                                 "CIST Bridge Identifier: %d / %s",
 544                                 cist_bridge_identifier_bridge_priority,
 545                                 cist_bridge_identifier_mac_str);
 546                 proto_tree_add_ether_hidden(mstp_tree, hf_bpdu_cist_bridge_identifier_mac, tvb,
 547                                        BPDU_CIST_BRIDGE_IDENTIFIER + 2, 6,
 548                                        cist_bridge_identifier_mac);
 549
 550                 cist_remaining_hops = tvb_get_guint8(tvb, BPDU_CIST_REMAINING_HOPS);
 551                 proto_tree_add_uint(mstp_tree, hf_bpdu_cist_remaining_hops, tvb,
 552                         BPDU_CIST_REMAINING_HOPS, 1, cist_remaining_hops);
 553
 554         /* MSTI messages */
 555                 offset = BPDU_MSTI;
 556                 length = tvb_reported_length_remaining(tvb, offset);
 557                 msti = 1;
 558                 while (length >= MSTI_MESSAGE_SIZE) {
 559                     msti_regional_root_mstid = tvb_get_guint8(tvb,  offset+ MSTI_REGIONAL_ROOT);
 560                     msti_regional_root_priority = (msti_regional_root_mstid &0xf0) << 8;
 561                     msti_regional_root_mstid = ((msti_regional_root_mstid & 0x0f) << 8) +
 562                                 tvb_get_guint8(tvb,  offset+ MSTI_REGIONAL_ROOT+1);
 563                     msti_regional_root_mac = tvb_get_ptr(tvb, offset+ MSTI_REGIONAL_ROOT + 2, 6);
 564                     msti_regional_root_mac_str = ether_to_str(msti_regional_root_mac);
 565
 566                     msti_item = proto_tree_add_text(mstp_tree, tvb, offset, 16,
 567                         "MSTID %d, Regional Root Identifier %d / %s",
 568                         msti_regional_root_mstid, msti_regional_root_priority,
 569                         msti_regional_root_mac_str);
 570                     msti_tree = proto_item_add_subtree(msti_item, ett_msti);
 571
 572                     /* flags */
 573                     flags = tvb_get_guint8(tvb, offset+MSTI_FLAGS);
 574                     flags_item = proto_tree_add_uint(msti_tree, hf_bpdu_msti_flags, tvb,
 575                         offset+MSTI_FLAGS, 1, flags);
 576                     flags_tree = proto_item_add_subtree(flags_item, ett_bpdu_flags);
 577
 578                     sep = initial_sep;
 579                     APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_TCACK, flags_item, "%sMaster");
 580                     proto_tree_add_boolean(flags_tree, hf_bpdu_flags_tcack, tvb,
 581                         offset+MSTI_FLAGS, 1, flags);
 582                     APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_AGREEMENT, flags_item, "%sAgreement");
 583                     proto_tree_add_boolean(flags_tree, hf_bpdu_flags_agreement, tvb,
 584                         offset+MSTI_FLAGS, 1, flags);
 585                     APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_FORWARDING, flags_item, "%sForwarding");
 586                     proto_tree_add_boolean(flags_tree, hf_bpdu_flags_forwarding, tvb,
 587                         offset+MSTI_FLAGS, 1, flags);
 588                     APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_LEARNING, flags_item, "%sLearning");
 589                     proto_tree_add_boolean(flags_tree, hf_bpdu_flags_learning, tvb,
 590                         offset+MSTI_FLAGS, 1, flags);
 591                     if (flags_item) {
 592                         guint8 port_role;
 593                         port_role = (flags & BPDU_FLAGS_PORT_ROLE_MASK) >> BPDU_FLAGS_PORT_ROLE_SHIFT;
 594                         proto_item_append_text(flags_item, "%sPort Role: %s", sep,
 595                                        val_to_str(port_role, role_vals, "Unknown (%u)"));
 596                     }
 597                     proto_tree_add_uint(flags_tree, hf_bpdu_flags_port_role, tvb,
 598                         offset+MSTI_FLAGS, 1, flags);
 599                     sep = cont_sep;
 600                     APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_PROPOSAL, flags_item, "%sProposal");
 601                     proto_tree_add_boolean(flags_tree, hf_bpdu_flags_proposal, tvb,
 602                         offset+MSTI_FLAGS, 1, flags);
 603                     APPEND_BOOLEAN_FLAG(flags & BPDU_FLAGS_TC, flags_item, "%sTopology Change");
 604                     proto_tree_add_boolean(flags_tree, hf_bpdu_flags_tc, tvb,
 605                         offset+MSTI_FLAGS, 1, flags);
 606                     if (sep != initial_sep) {         /* We put something in; put in the terminating ")" */
 607                         proto_item_append_text(flags_item, ")");
 608                     }
 609
 610                     /* pri, MSTID, Regional root */
 611                     proto_tree_add_ether_hidden(msti_tree, hf_bpdu_msti_regional_root_mac, tvb,
 612                                        offset + MSTI_REGIONAL_ROOT + 2, 6,
 613                                        msti_regional_root_mac);
 614                     proto_tree_add_text(msti_tree, tvb, offset + MSTI_REGIONAL_ROOT, 8,
 615                                 "MSTID %d, priority %d Root Identifier %s",
 616                                 msti_regional_root_mstid, msti_regional_root_priority,
 617                                 msti_regional_root_mac_str);
 618
 619
 620                     msti_internal_root_path_cost = tvb_get_ntohs(tvb, offset+MSTI_INTERNAL_ROOT_PATH_COST);
 621                     proto_tree_add_uint(msti_tree, hf_bpdu_msti_internal_root_path_cost, tvb,
 622                         offset+MSTI_INTERNAL_ROOT_PATH_COST, 4, msti_internal_root_path_cost);
 623
 624                     msti_bridge_identifier_priority = tvb_get_guint8(tvb, offset+MSTI_BRIDGE_IDENTIFIER_PRIORITY) >> 4;
 625                     msti_port_identifier_priority = tvb_get_guint8(tvb, offset+MSTI_PORT_IDENTIFIER_PRIORITY) >> 4;
 626
 627                     proto_tree_add_uint(msti_tree, hf_bpdu_msti_bridge_identifier_priority, tvb,
 628                         offset+MSTI_BRIDGE_IDENTIFIER_PRIORITY, 1, msti_bridge_identifier_priority);
 629                     proto_tree_add_uint(msti_tree, hf_bpdu_msti_port_identifier_priority, tvb,
 630                         offset+MSTI_PORT_IDENTIFIER_PRIORITY, 1, msti_port_identifier_priority);
 631
 632                     msti_remaining_hops = tvb_get_guint8(tvb, offset+MSTI_REMAINING_HOPS);
 633                     proto_tree_add_uint(msti_tree, hf_bpdu_msti_remaining_hops, tvb,
 634                         offset + MSTI_REMAINING_HOPS, 1, msti_remaining_hops);
 635
 636                     length -= MSTI_MESSAGE_SIZE;
 637                     offset += MSTI_MESSAGE_SIZE;
 638                     msti++;
 639                 }
 640
 641             }
 642       }
 643 }
 644
 645 static const true_false_string yesno = {
 646         "Yes",
 647         "No"
 648 };
 649
 650 void
 651 proto_register_bpdu(void)
 652 {
 653
 654   static hf_register_info hf[] = {
 655     { &hf_bpdu_proto_id,
 656       { "Protocol Identifier",          "stp.protocol",
 657         FT_UINT16,      BASE_HEX,       VALS(&protocol_id_vals), 0x0,
 658         "", HFILL }},
 659     { &hf_bpdu_version_id,
 660       { "Protocol Version Identifier",  "stp.version",
 661         FT_UINT8,       BASE_DEC,       VALS(&version_id_vals), 0x0,
 662         "", HFILL }},
 663     { &hf_bpdu_type,
 664       { "BPDU Type",                    "stp.type",
 665         FT_UINT8,       BASE_HEX,       VALS(&bpdu_type_vals),  0x0,
 666         "", HFILL }},
 667     { &hf_bpdu_flags,
 668       { "BPDU flags",                   "stp.flags",
 669         FT_UINT8,       BASE_HEX,       NULL,   0x0,
 670         "", HFILL }},
 671     { &hf_bpdu_flags_tcack,
 672       { "Topology Change Acknowledgment",  "stp.flags.tcack",
 673         FT_BOOLEAN,     8,              TFS(&yesno),    BPDU_FLAGS_TCACK,
 674         "", HFILL }},
 675     { &hf_bpdu_flags_agreement,
 676       { "Agreement",                    "stp.flags.agreement",
 677         FT_BOOLEAN,     8,              TFS(&yesno),    BPDU_FLAGS_AGREEMENT,
 678         "", HFILL }},
 679     { &hf_bpdu_flags_forwarding,
 680       { "Forwarding",                   "stp.flags.forwarding",
 681         FT_BOOLEAN,     8,              TFS(&yesno),    BPDU_FLAGS_FORWARDING,
 682         "", HFILL }},
 683     { &hf_bpdu_flags_learning,
 684       { "Learning",                     "stp.flags.learning",
 685         FT_BOOLEAN,     8,              TFS(&yesno),    BPDU_FLAGS_LEARNING,
 686         "", HFILL }},
 687     { &hf_bpdu_flags_port_role,
 688       { "Port Role",                    "stp.flags.port_role",
 689         FT_UINT8,       BASE_DEC,       VALS(role_vals),        BPDU_FLAGS_PORT_ROLE_MASK,
 690         "", HFILL }},
 691     { &hf_bpdu_flags_proposal,
 692       { "Proposal",                     "stp.flags.proposal",
 693         FT_BOOLEAN,     8,              TFS(&yesno),    BPDU_FLAGS_PROPOSAL,
 694         "", HFILL }},
 695     { &hf_bpdu_flags_tc,
 696       { "Topology Change",              "stp.flags.tc",
 697         FT_BOOLEAN,     8,              TFS(&yesno),    BPDU_FLAGS_TC,
 698         "", HFILL }},
 699     { &hf_bpdu_root_mac,
 700       { "Root Identifier",              "stp.root.hw",
 701         FT_ETHER,       BASE_NONE,      NULL,   0x0,
 702         "", HFILL }},
 703     { &hf_bpdu_root_cost,
 704       { "Root Path Cost",               "stp.root.cost",
 705         FT_UINT32,      BASE_DEC,       NULL,   0x0,
 706         "", HFILL }},
 707     { &hf_bpdu_bridge_mac,
 708       { "Bridge Identifier",            "stp.bridge.hw",
 709         FT_ETHER,       BASE_NONE,      NULL,   0x0,
 710         "", HFILL }},
 711     { &hf_bpdu_port_id,
 712       { "Port identifier",              "stp.port",
 713         FT_UINT16,      BASE_HEX,       NULL,   0x0,
 714         "", HFILL }},
 715     { &hf_bpdu_msg_age,
 716       { "Message Age",                  "stp.msg_age",
 717         FT_DOUBLE,      BASE_NONE,      NULL,   0x0,
 718         "", HFILL }},
 719     { &hf_bpdu_max_age,
 720       { "Max Age",                      "stp.max_age",
 721         FT_DOUBLE,      BASE_NONE,      NULL,   0x0,
 722         "", HFILL }},
 723     { &hf_bpdu_hello_time,
 724       { "Hello Time",                   "stp.hello",
 725         FT_DOUBLE,      BASE_NONE,      NULL,   0x0,
 726         "", HFILL }},
 727     { &hf_bpdu_forward_delay,
 728       { "Forward Delay",                "stp.forward",
 729         FT_DOUBLE,      BASE_NONE,      NULL,   0x0,
 730         "", HFILL }},
 731     { &hf_bpdu_version_1_length,
 732       { "Version 1 Length",             "stp.version_1_length",
 733         FT_UINT8,       BASE_DEC,       NULL,   0x0,
 734         "", HFILL }},
 735     { &hf_bpdu_version_3_length,
 736       { "MST Extension, Length",                "mstp.version_3_length",
 737         FT_UINT16,      BASE_DEC,       NULL,   0x0,
 738         "", HFILL }},
 739     { &hf_bpdu_mst_config_format_selector,
 740       { "MST Config ID format selector",                "mstp.config_format_selector",
 741         FT_UINT8,       BASE_DEC,       NULL,   0x0,
 742         "", HFILL }},
 743     { &hf_bpdu_mst_config_name,
 744       { "MST Config name",              "mstp.config_name",
 745         FT_STRING,      BASE_DEC,       NULL,   0x0,
 746         "", HFILL }},
 747     { &hf_bpdu_mst_config_revision_level,
 748       { "MST Config revision",          "mstp.config_revision_level",
 749         FT_UINT16,      BASE_DEC,       NULL,   0x0,
 750         "", HFILL }},
 751     { &hf_bpdu_mst_config_digest,
 752       { "MST Config digest",            "mstp.config_digest",
 753         FT_BYTES,       BASE_DEC,       NULL,   0x0,
 754         "", HFILL }},
 755     { &hf_bpdu_cist_internal_root_path_cost,
 756       { "CIST Internal Root Path Cost",         "mstp.cist_internal_root_path_cost",
 757         FT_UINT32,      BASE_DEC,       NULL,   0x0,
 758         "", HFILL }},
 759     { &hf_bpdu_cist_bridge_identifier_mac,
 760       { "CIST Bridge Identifier",               "mstp.cist_bridge.hw",
 761         FT_ETHER,       BASE_DEC,       NULL,   0x0,
 762         "", HFILL }},
 763     { &hf_bpdu_cist_remaining_hops,
 764       { "CIST Remaining hops",          "mstp.cist_remaining_hops",
 765         FT_UINT8,       BASE_DEC,       NULL,   0x0,
 766         "", HFILL }},
 767     { &hf_bpdu_msti_flags,
 768       { "MSTI flags",                   "mstp.msti.flags",
 769         FT_UINT8,       BASE_HEX,       NULL,   0x0,
 770         "", HFILL }},
 771     { &hf_bpdu_msti_regional_root_mac,
 772       { "Regional Root",                "mstp.msti.root.hw",
 773         FT_ETHER,       BASE_DEC,       NULL,   0x0,
 774         "", HFILL }},
 775     { &hf_bpdu_msti_internal_root_path_cost,
 776       { "Internal root path cost",              "mstp.msti.root_cost",
 777         FT_UINT32,      BASE_DEC,       NULL,   0x0,
 778         "", HFILL }},
 779     { &hf_bpdu_msti_bridge_identifier_priority,
 780       { "Bridge Identifier Priority",           "mstp.msti.bridge_priority",
 781         FT_UINT8,       BASE_DEC,       NULL,   0x0,
 782         "", HFILL }},
 783     { &hf_bpdu_msti_port_identifier_priority,
 784       { "Port identifier prority",              "mstp.msti.port_priority",
 785         FT_UINT8,       BASE_DEC,       NULL,   0x0,
 786         "", HFILL }},
 787     { &hf_bpdu_msti_remaining_hops,
 788       { "Remaining hops",               "mstp.msti.remaining_hops",
 789         FT_UINT8,       BASE_DEC,       NULL,   0x0,
 790         "", HFILL }},
 791
 792   };
 793   static gint *ett[] = {
 794     &ett_bpdu,
 795     &ett_bpdu_flags,
 796     &ett_mstp,
 797     &ett_msti
 798   };
 799
 800   proto_bpdu = proto_register_protocol("Spanning Tree Protocol", "STP", "stp");
 801   proto_register_field_array(proto_bpdu, hf, array_length(hf));
 802   proto_register_subtree_array(ett, array_length(ett));
 803
 804   register_dissector("bpdu", dissect_bpdu, proto_bpdu);
 805 }
 806
 807 void
 808 proto_reg_handoff_bpdu(void)
 809 {
 810   dissector_handle_t bpdu_handle;
 811
 812   /*
 813    * Get handle for the GVRP dissector.
 814    */
 815   gvrp_handle = find_dissector("gvrp");
 816
 817   /*
 818    * Get handle for the GMRP dissector.
 819    */
 820   gmrp_handle = find_dissector("gmrp");
 821   data_handle = find_dissector("data");
 822
 823   bpdu_handle = find_dissector("bpdu");
 824   dissector_add("llc.dsap", SAP_BPDU, bpdu_handle);
 825   dissector_add("ppp.protocol", PPP_BPDU, bpdu_handle);
 826   dissector_add("chdlctype", CHDLCTYPE_BPDU, bpdu_handle);
 827   dissector_add("llc.cisco_pid", 0x010b, bpdu_handle);
 828 }