packet-bpdu.c

   1 /* packet-bpdu.c
   2  * Routines for BPDU (Spanning Tree Protocol) disassembly
   3  *
   4  * $Id: packet-bpdu.c,v 1.18 2001/01/03 06:55:27 guy Exp $
   5  *
   6  * Copyright 1999 Christophe Tronche <ch.tronche@computer.org>
   7  *
   8  * Ethereal - Network traffic analyzer
   9  * By Gerald Combs <gerald@zing.org>
  10  * Copyright 1998 Gerald Combs
  11  *
  12  *
  13  * This program is free software; you can redistribute it and/or
  14  * modify it under the terms of the GNU General Public License
  15  * as published by the Free Software Foundation; either version 2
  16  * of the License, or (at your option) any later version.
  17  *
  18  * This program is distributed in the hope that it will be useful,
  19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21  * GNU General Public License for more details.
  22  *
  23  * You should have received a copy of the GNU General Public License
  24  * along with this program; if not, write to the Free Software
  25  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  26  */
  27
  28 #ifdef HAVE_CONFIG_H
  29 # include "config.h"
  30 #endif
  31
  32 #ifdef HAVE_SYS_TYPES_H
  33 # include <sys/types.h>
  34 #endif
  35
  36 #ifdef HAVE_NETINET_IN_H
  37 # include <netinet/in.h>
  38 #endif
  39
  40 #include <stdio.h>
  41 #include <string.h>
  42 #include <glib.h>
  43 #include "packet.h"
  44 #include "llcsaps.h"
  45 #include "resolv.h"
  46
  47 /* Include this for GVRP dissector */
  48 #include "packet-gvrp.h"
  49
  50 /* Offsets of fields within a BPDU */
  51
  52 #define BPDU_IDENTIFIER          0
  53 #define BPDU_VERSION_IDENTIFIER  2
  54 #define BPDU_TYPE                3
  55 #define BPDU_FLAGS               4
  56 #define BPDU_ROOT_IDENTIFIER     5
  57 #define BPDU_ROOT_PATH_COST     13
  58 #define BPDU_BRIDGE_IDENTIFIER  17
  59 #define BPDU_PORT_IDENTIFIER    25
  60 #define BPDU_MESSAGE_AGE        27
  61 #define BPDU_MAX_AGE            29
  62 #define BPDU_HELLO_TIME         31
  63 #define BPDU_FORWARD_DELAY      33
  64
  65 static int proto_bpdu = -1;
  66 static int hf_bpdu_proto_id = -1;
  67 static int hf_bpdu_version_id = -1;
  68 static int hf_bpdu_type = -1;
  69 static int hf_bpdu_flags = -1;
  70 static int hf_bpdu_root_mac = -1;
  71 static int hf_bpdu_root_cost = -1;
  72 static int hf_bpdu_bridge_mac = -1;
  73 static int hf_bpdu_port_id = -1;
  74 static int hf_bpdu_msg_age = -1;
  75 static int hf_bpdu_max_age = -1;
  76 static int hf_bpdu_hello_time = -1;
  77 static int hf_bpdu_forward_delay = -1;
  78
  79 static gint ett_bpdu = -1;
  80
  81 static void
  82 dissect_bpdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) {
  83       guint16 protocol_identifier;
  84       guint8  protocol_version_identifier;
  85       guint8  bpdu_type;
  86       guint8  flags;
  87       guint16 root_identifier_bridge_priority;
  88       guint8  *root_identifier_mac;
  89       gchar   *root_identifier_mac_str;
  90       guint32 root_path_cost;
  91       guint16 bridge_identifier_bridge_priority;
  92       guint8  *bridge_identifier_mac;
  93       gchar   *bridge_identifier_mac_str;
  94       guint16 port_identifier;
  95       double message_age;
  96       double max_age;
  97       double hello_time;
  98       double forward_delay;
  99
 100       proto_tree *bpdu_tree;
 101       proto_item *ti;
 102
 103       CHECK_DISPLAY_AS_DATA(proto_bpdu, tvb, pinfo, tree);
 104
 105       /* GARP application frames require special interpretation of the
 106          destination address field; otherwise, they will be mistaken as
 107          BPDU frames.
 108          Fortunately, they can be recognized by checking the first 6 octets
 109          of the destination address, which are in the range from
 110          01-80-C2-00-00-20 to 01-80-C2-00-00-2F.
 111
 112          Yes - we *do* need to check the destination address type;
 113          on Linux cooked captures, there *is* no destination address,
 114          so it's AT_NONE. */
 115       if (pinfo->dl_dst.type == AT_ETHER &&
 116           pinfo->dl_dst.data[0] == 0x01 && pinfo->dl_dst.data[1] == 0x80 &&
 117           pinfo->dl_dst.data[2] == 0xC2 && pinfo->dl_dst.data[3] == 0x00 &&
 118           pinfo->dl_dst.data[4] == 0x00 && ((pinfo->dl_dst.data[5] & 0x20) == 0x20)) {
 119
 120             protocol_identifier = tvb_get_ntohs(tvb, BPDU_IDENTIFIER);
 121
 122             switch (pinfo->dl_dst.data[5]) {
 123
 124             case 0x20:
 125                   /* Future expansion for GMRP */
 126                   break;
 127
 128             case 0x21:
 129                   /* for GVRP */
 130                   dissect_gvrp(tvb, pinfo, tree);
 131                   return;
 132             }
 133
 134             pinfo->current_proto = "GARP";
 135
 136             if (check_col(pinfo->fd, COL_PROTOCOL)) {
 137                     col_set_str(pinfo->fd, COL_PROTOCOL, "GARP");
 138                     /* Generic Attribute Registration Protocol */
 139             }
 140
 141             if (check_col(pinfo->fd, COL_INFO)) {
 142                     col_add_fstr(pinfo->fd, COL_INFO,
 143                         "Unknown GARP application (0x%02X)",
 144                         pinfo->dl_dst.data[5]);
 145             }
 146
 147             return;
 148       }
 149
 150       pinfo->current_proto = "STP";
 151
 152       bpdu_type = tvb_get_guint8(tvb, BPDU_TYPE);
 153       flags = tvb_get_guint8(tvb, BPDU_FLAGS);
 154       root_identifier_bridge_priority = tvb_get_ntohs(tvb, BPDU_ROOT_IDENTIFIER);
 155       root_identifier_mac = tvb_get_ptr(tvb, BPDU_ROOT_IDENTIFIER + 2, 6);
 156       root_identifier_mac_str = ether_to_str(root_identifier_mac);
 157       root_path_cost = tvb_get_ntohl(tvb, BPDU_ROOT_PATH_COST);
 158       port_identifier = tvb_get_ntohs(tvb, BPDU_PORT_IDENTIFIER);
 159
 160       if (check_col(pinfo->fd, COL_PROTOCOL)) {
 161             col_set_str(pinfo->fd, COL_PROTOCOL, "STP"); /* Spanning Tree Protocol */
 162       }
 163
 164       if (check_col(pinfo->fd, COL_INFO)) {
 165             if (bpdu_type == 0)
 166                   col_add_fstr(pinfo->fd, COL_INFO, "Conf. %sRoot = %d/%s  Cost = %d  Port = 0x%04x",
 167                                flags & 0x1 ? "TC + " : "",
 168                                root_identifier_bridge_priority, root_identifier_mac_str, root_path_cost,
 169                                port_identifier);
 170             else if (bpdu_type == 0x80)
 171                   col_add_fstr(pinfo->fd, COL_INFO, "Topology Change Notification");
 172       }
 173
 174       if (tree) {
 175             protocol_identifier = tvb_get_ntohs(tvb, BPDU_IDENTIFIER);
 176             protocol_version_identifier = tvb_get_guint8(tvb, BPDU_VERSION_IDENTIFIER);
 177
 178             ti = proto_tree_add_protocol_format(tree, proto_bpdu, tvb, 0, 35,
 179                                 "Spanning Tree Protocol");
 180             bpdu_tree = proto_item_add_subtree(ti, ett_bpdu);
 181             proto_tree_add_uint_format(bpdu_tree, hf_bpdu_proto_id, tvb,
 182                                        BPDU_IDENTIFIER, 2,
 183                                        protocol_identifier,
 184                                        "Protocol Identifier: 0x%04x (%s)",
 185                                        protocol_identifier,
 186                                        protocol_identifier == 0 ?
 187                                        "Spanning Tree" : "Unknown Protocol");
 188
 189             proto_tree_add_uint(bpdu_tree, hf_bpdu_version_id, tvb,
 190                                 BPDU_VERSION_IDENTIFIER, 1,
 191                                 protocol_version_identifier);
 192             if (protocol_version_identifier != 0)
 193                   proto_tree_add_text(bpdu_tree, tvb, BPDU_VERSION_IDENTIFIER, 1,
 194                   "   (Warning: this version of Ethereal only knows about version = 0)");
 195             proto_tree_add_uint_format(bpdu_tree, hf_bpdu_type, tvb,
 196                                        BPDU_TYPE, 1,
 197                                        bpdu_type,
 198                                        "BPDU Type: 0x%02x (%s)",
 199                                        bpdu_type,
 200                                        bpdu_type == 0 ? "Configuration" :
 201                                        bpdu_type == 0x80 ? "Topology Change Notification" : "Unknown");
 202
 203             if (bpdu_type != 0) {
 204               dissect_data(tvb, BPDU_TYPE + 1, pinfo, tree);
 205               return;
 206             }
 207
 208             bridge_identifier_bridge_priority = tvb_get_ntohs(tvb, BPDU_BRIDGE_IDENTIFIER);
 209             bridge_identifier_mac = tvb_get_ptr(tvb, BPDU_BRIDGE_IDENTIFIER + 2, 6);
 210             bridge_identifier_mac_str = ether_to_str(bridge_identifier_mac);
 211             message_age = tvb_get_ntohs(tvb, BPDU_MESSAGE_AGE) / 256.0;
 212             max_age = tvb_get_ntohs(tvb, BPDU_MAX_AGE) / 256.0;
 213             hello_time = tvb_get_ntohs(tvb, BPDU_HELLO_TIME) / 256.0;
 214             forward_delay = tvb_get_ntohs(tvb, BPDU_FORWARD_DELAY) / 256.0;
 215
 216             proto_tree_add_uint(bpdu_tree, hf_bpdu_flags, tvb,
 217                                 BPDU_FLAGS, 1, flags);
 218             if (flags & 0x80)
 219                   proto_tree_add_text(bpdu_tree, tvb, BPDU_FLAGS, 1, "   1... ....  Topology Change Acknowledgment");
 220             if (flags & 0x01)
 221                   proto_tree_add_text(bpdu_tree, tvb, BPDU_FLAGS, 1, "   .... ...1  Topology Change");
 222
 223             proto_tree_add_ether_hidden(bpdu_tree, hf_bpdu_root_mac, tvb,
 224                                        BPDU_ROOT_IDENTIFIER + 2, 6,
 225                                        root_identifier_mac);
 226             proto_tree_add_text(bpdu_tree, tvb,
 227                                 BPDU_ROOT_IDENTIFIER, 8,
 228                                 "Root Identifier: %d / %s",
 229                                 root_identifier_bridge_priority,
 230                                 root_identifier_mac_str);
 231             proto_tree_add_uint(bpdu_tree, hf_bpdu_root_cost, tvb,
 232                                 BPDU_ROOT_PATH_COST, 4,
 233                                 root_path_cost);
 234             proto_tree_add_text(bpdu_tree, tvb,
 235                                 BPDU_BRIDGE_IDENTIFIER, 8,
 236                                 "Bridge Identifier: %d / %s",
 237                                 bridge_identifier_bridge_priority,
 238                                 bridge_identifier_mac_str);
 239             proto_tree_add_ether_hidden(bpdu_tree, hf_bpdu_bridge_mac, tvb,
 240                                        BPDU_BRIDGE_IDENTIFIER + 2, 6,
 241                                        bridge_identifier_mac);
 242             proto_tree_add_uint(bpdu_tree, hf_bpdu_port_id, tvb,
 243                                 BPDU_PORT_IDENTIFIER, 2,
 244                                 port_identifier);
 245             proto_tree_add_double(bpdu_tree, hf_bpdu_msg_age, tvb,
 246                                 BPDU_MESSAGE_AGE, 2,
 247                                 message_age);
 248             proto_tree_add_double(bpdu_tree, hf_bpdu_max_age, tvb,
 249                                 BPDU_MAX_AGE, 2,
 250                                 max_age);
 251             proto_tree_add_double(bpdu_tree, hf_bpdu_hello_time, tvb,
 252                                 BPDU_HELLO_TIME, 2,
 253                                 hello_time);
 254             proto_tree_add_double(bpdu_tree, hf_bpdu_forward_delay, tvb,
 255                                 BPDU_FORWARD_DELAY, 2,
 256                                 forward_delay);
 257       }
 258 }
 259
 260 void
 261 proto_register_bpdu(void)
 262 {
 263
 264   static hf_register_info hf[] = {
 265     { &hf_bpdu_proto_id,
 266       { "Protocol Identifier",          "stp.protocol",
 267         FT_UINT16,      BASE_HEX,       NULL,   0x0,
 268         "" }},
 269     { &hf_bpdu_version_id,
 270       { "Protocol Version Identifier",  "stp.version",
 271         FT_UINT8,       BASE_DEC,       NULL,   0x0,
 272         "" }},
 273     { &hf_bpdu_type,
 274       { "BPDU type",                    "stp.type",
 275         FT_UINT8,       BASE_HEX,       NULL,   0x0,
 276         "" }},
 277     { &hf_bpdu_flags,
 278       { "BPDU flags",                   "stp.flags",
 279         FT_UINT8,       BASE_HEX,       NULL,   0x0,
 280         "" }},
 281     { &hf_bpdu_root_mac,
 282       { "Root Identifier",              "stp.root.hw",
 283         FT_ETHER,       BASE_NONE,      NULL,   0x0,
 284         "" }},
 285     { &hf_bpdu_root_cost,
 286       { "Root Path Cost",               "stp.root.cost",
 287         FT_UINT32,      BASE_DEC,       NULL,   0x0,
 288         "" }},
 289     { &hf_bpdu_bridge_mac,
 290       { "Bridge Identifier",            "stp.bridge.hw",
 291         FT_ETHER,       BASE_NONE,      NULL,   0x0,
 292         ""}},
 293     { &hf_bpdu_port_id,
 294       { "Port identifier",              "stp.port",
 295         FT_UINT16,      BASE_HEX,       NULL,   0x0,
 296         ""}},
 297     { &hf_bpdu_msg_age,
 298       { "Message Age",                  "stp.msg_age",
 299         FT_DOUBLE,      BASE_NONE,      NULL,   0x0,
 300         "" }},
 301     { &hf_bpdu_max_age,
 302       { "Max Age",                      "stp.max_age",
 303         FT_DOUBLE,      BASE_NONE,      NULL,   0x0,
 304         "" }},
 305     { &hf_bpdu_hello_time,
 306       { "Hello Time",                   "stp.hello",
 307         FT_DOUBLE,      BASE_NONE,      NULL,   0x0,
 308         "" }},
 309     { &hf_bpdu_forward_delay,
 310       { "Forward Delay",                "stp.forward",
 311         FT_DOUBLE,      BASE_NONE,      NULL,   0x0,
 312         "" }},
 313   };
 314   static gint *ett[] = {
 315     &ett_bpdu,
 316   };
 317
 318   proto_bpdu = proto_register_protocol("Spanning Tree Protocol", "STP", "stp");
 319   proto_register_field_array(proto_bpdu, hf, array_length(hf));
 320   proto_register_subtree_array(ett, array_length(ett));
 321
 322   register_dissector("bpdu", dissect_bpdu);
 323 }
 324
 325 void
 326 proto_reg_handoff_bpdu(void)
 327 {
 328   dissector_add("llc.dsap", SAP_BPDU, dissect_bpdu);
 329 }