epan/dissectors/packet-dec-bpdu.c

   1 /* packet-dec-bpdu.c
   2  * Routines for DEC BPDU (DEC Spanning Tree Protocol) disassembly
   3  *
   4  * Copyright 2001 Paul Ionescu <paul@acorp.ro>
   5  *
   6  * Wireshark - Network traffic analyzer
   7  * By Gerald Combs <gerald@wireshark.org>
   8  * Copyright 1998 Gerald Combs
   9  *
  10  * SPDX-License-Identifier: GPL-2.0-or-later
  11  */
  12
  13 #include "config.h"
  14
  15 #include <epan/packet.h>
  16 #include <epan/etypes.h>
  17 #include <epan/ppptypes.h>
  18 #include <epan/tfs.h>
  19
  20 /* Offsets of fields within a BPDU */
  21
  22 #define BPDU_DEC_CODE            0
  23 #define BPDU_TYPE                1
  24 #define BPDU_VERSION             2
  25 #define BPDU_FLAGS               3
  26 #define BPDU_ROOT_PRI            4
  27 #define BPDU_ROOT_MAC            6
  28 #define BPDU_ROOT_PATH_COST     12
  29 #define BPDU_BRIDGE_PRI         14
  30 #define BPDU_BRIDGE_MAC         16
  31 #define BPDU_PORT_IDENTIFIER    22
  32 #define BPDU_MESSAGE_AGE        23
  33 #define BPDU_HELLO_TIME         24
  34 #define BPDU_MAX_AGE            25
  35 #define BPDU_FORWARD_DELAY      26
  36
  37 #define DEC_BPDU_SIZE           27
  38
  39 /* Flag bits */
  40
  41 #define BPDU_FLAGS_SHORT_TIMERS         0x80
  42 #define BPDU_FLAGS_TCACK                0x02
  43 #define BPDU_FLAGS_TC                   0x01
  44
  45 void proto_register_dec_bpdu(void);
  46 void proto_reg_handoff_dec_bpdu(void);
  47
  48 static dissector_handle_t dec_bpdu_handle;
  49
  50 static int proto_dec_bpdu;
  51 static int hf_dec_bpdu_proto_id;
  52 static int hf_dec_bpdu_type;
  53 static int hf_dec_bpdu_version_id;
  54 static int hf_dec_bpdu_flags;
  55 static int hf_dec_bpdu_flags_short_timers;
  56 static int hf_dec_bpdu_flags_tcack;
  57 static int hf_dec_bpdu_flags_tc;
  58 static int hf_dec_bpdu_root_pri;
  59 static int hf_dec_bpdu_root_mac;
  60 static int hf_dec_bpdu_root_cost;
  61 static int hf_dec_bpdu_bridge_pri;
  62 static int hf_dec_bpdu_bridge_mac;
  63 static int hf_dec_bpdu_port_id;
  64 static int hf_dec_bpdu_msg_age;
  65 static int hf_dec_bpdu_hello_time;
  66 static int hf_dec_bpdu_max_age;
  67 static int hf_dec_bpdu_forward_delay;
  68
  69 static int ett_dec_bpdu;
  70 static int ett_dec_bpdu_flags;
  71
  72 static const value_string protocol_id_vals[] = {
  73     { 0xe1, "DEC Spanning Tree Protocol" },
  74     { 0,    NULL }
  75 };
  76
  77 #define BPDU_TYPE_TOPOLOGY_CHANGE       2
  78 #define BPDU_TYPE_HELLO                 25
  79
  80 static const value_string bpdu_type_vals[] = {
  81     { BPDU_TYPE_TOPOLOGY_CHANGE, "Topology Change Notification" },
  82     { BPDU_TYPE_HELLO,           "Hello Packet" },
  83     { 0,                         NULL }
  84 };
  85
  86 static int
  87 dissect_dec_bpdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
  88 {
  89     uint8_t bpdu_type;
  90     proto_tree *bpdu_tree;
  91     proto_item *ti;
  92     static int * const bpdu_flags[] = {
  93         &hf_dec_bpdu_flags_short_timers,
  94         &hf_dec_bpdu_flags_tcack,
  95         &hf_dec_bpdu_flags_tc,
  96         NULL
  97     };
  98
  99     col_set_str(pinfo->cinfo, COL_PROTOCOL, "DEC_STP");
 100     col_clear(pinfo->cinfo, COL_INFO);
 101
 102     bpdu_type = tvb_get_uint8(tvb, BPDU_TYPE);
 103
 104     col_add_str(pinfo->cinfo, COL_INFO,
 105                 val_to_str(bpdu_type, bpdu_type_vals,
 106                            "Unknown BPDU type (%u)"));
 107
 108     set_actual_length(tvb, DEC_BPDU_SIZE);
 109
 110     if (tree) {
 111         ti = proto_tree_add_item(tree, proto_dec_bpdu, tvb, 0, DEC_BPDU_SIZE,
 112                                  ENC_NA);
 113         bpdu_tree = proto_item_add_subtree(ti, ett_dec_bpdu);
 114
 115         proto_tree_add_item(bpdu_tree, hf_dec_bpdu_proto_id, tvb,
 116                             BPDU_DEC_CODE, 1, ENC_BIG_ENDIAN);
 117
 118         proto_tree_add_uint(bpdu_tree, hf_dec_bpdu_type, tvb,
 119                             BPDU_TYPE, 1, bpdu_type);
 120
 121         proto_tree_add_item(bpdu_tree, hf_dec_bpdu_version_id, tvb,
 122                             BPDU_VERSION, 1, ENC_BIG_ENDIAN);
 123
 124         proto_tree_add_bitmask_with_flags(bpdu_tree, tvb, BPDU_FLAGS, hf_dec_bpdu_flags, ett_dec_bpdu_flags, bpdu_flags, ENC_NA, BMT_NO_FALSE|BMT_NO_TFS);
 125         proto_tree_add_item(bpdu_tree, hf_dec_bpdu_root_pri, tvb,
 126                             BPDU_ROOT_PRI, 2, ENC_BIG_ENDIAN);
 127         proto_tree_add_item(bpdu_tree, hf_dec_bpdu_root_mac, tvb,
 128                             BPDU_ROOT_MAC, 6, ENC_NA);
 129         proto_tree_add_item(bpdu_tree, hf_dec_bpdu_root_cost, tvb,
 130                             BPDU_ROOT_PATH_COST, 2, ENC_BIG_ENDIAN);
 131         proto_tree_add_item(bpdu_tree, hf_dec_bpdu_bridge_pri, tvb,
 132                             BPDU_BRIDGE_PRI, 2, ENC_BIG_ENDIAN);
 133         proto_tree_add_item(bpdu_tree, hf_dec_bpdu_bridge_mac, tvb,
 134                             BPDU_BRIDGE_MAC, 6, ENC_NA);
 135         proto_tree_add_item(bpdu_tree, hf_dec_bpdu_port_id, tvb,
 136                             BPDU_PORT_IDENTIFIER, 1, ENC_BIG_ENDIAN);
 137         proto_tree_add_item(bpdu_tree, hf_dec_bpdu_msg_age, tvb,
 138                             BPDU_MESSAGE_AGE, 1, ENC_BIG_ENDIAN);
 139         proto_tree_add_item(bpdu_tree, hf_dec_bpdu_hello_time, tvb,
 140                             BPDU_HELLO_TIME, 1, ENC_BIG_ENDIAN);
 141         proto_tree_add_item(bpdu_tree, hf_dec_bpdu_max_age, tvb,
 142                             BPDU_MAX_AGE, 1, ENC_BIG_ENDIAN);
 143         proto_tree_add_item(bpdu_tree, hf_dec_bpdu_forward_delay, tvb,
 144                             BPDU_FORWARD_DELAY, 1, ENC_BIG_ENDIAN);
 145
 146     }
 147     return tvb_captured_length(tvb);
 148 }
 149
 150 void
 151 proto_register_dec_bpdu(void)
 152 {
 153
 154     static hf_register_info hf[] = {
 155         { &hf_dec_bpdu_proto_id,
 156           { "Protocol Identifier",          "dec_stp.protocol",
 157             FT_UINT8,       BASE_HEX,       VALS(protocol_id_vals), 0x0,
 158             NULL, HFILL }},
 159         { &hf_dec_bpdu_type,
 160           { "BPDU Type",                    "dec_stp.type",
 161             FT_UINT8,       BASE_DEC,       VALS(bpdu_type_vals),   0x0,
 162             NULL, HFILL }},
 163         { &hf_dec_bpdu_version_id,
 164           { "BPDU Version",                 "dec_stp.version",
 165             FT_UINT8,       BASE_DEC,       NULL,   0x0,
 166             NULL, HFILL }},
 167         { &hf_dec_bpdu_flags,
 168           { "BPDU flags",                   "dec_stp.flags",
 169             FT_UINT8,       BASE_HEX,       NULL,   0x0,
 170             NULL, HFILL }},
 171         { &hf_dec_bpdu_flags_short_timers,
 172           { "Use short timers",             "dec_stp.flags.short_timers",
 173             FT_BOOLEAN,     8,              TFS(&tfs_yes_no),       BPDU_FLAGS_SHORT_TIMERS,
 174             NULL, HFILL }},
 175         { &hf_dec_bpdu_flags_tcack,
 176           { "Topology Change Acknowledgment",  "dec_stp.flags.tcack",
 177             FT_BOOLEAN,     8,              TFS(&tfs_yes_no),       BPDU_FLAGS_TCACK,
 178             NULL, HFILL }},
 179         { &hf_dec_bpdu_flags_tc,
 180           { "Topology Change",              "dec_stp.flags.tc",
 181             FT_BOOLEAN,     8,              TFS(&tfs_yes_no),       BPDU_FLAGS_TC,
 182             NULL, HFILL }},
 183         { &hf_dec_bpdu_root_pri,
 184           { "Root Priority",                "dec_stp.root.pri",
 185             FT_UINT16,      BASE_DEC,       NULL,   0x0,
 186             NULL, HFILL }},
 187         { &hf_dec_bpdu_root_mac,
 188           { "Root MAC",                     "dec_stp.root.mac",
 189             FT_ETHER,       BASE_NONE,      NULL,   0x0,
 190             NULL, HFILL }},
 191         { &hf_dec_bpdu_root_cost,
 192           { "Root Path Cost",               "dec_stp.root.cost",
 193             FT_UINT16,      BASE_DEC,       NULL,   0x0,
 194             NULL, HFILL }},
 195         { &hf_dec_bpdu_bridge_pri,
 196           { "Bridge Priority",              "dec_stp.bridge.pri",
 197             FT_UINT16,      BASE_DEC,       NULL,   0x0,
 198             NULL, HFILL }},
 199         { &hf_dec_bpdu_bridge_mac,
 200           { "Bridge MAC",                   "dec_stp.bridge.mac",
 201             FT_ETHER,       BASE_NONE,      NULL,   0x0,
 202             NULL, HFILL }},
 203         { &hf_dec_bpdu_port_id,
 204           { "Port identifier",              "dec_stp.port",
 205             FT_UINT8,       BASE_DEC,       NULL,   0x0,
 206             NULL, HFILL }},
 207         { &hf_dec_bpdu_msg_age,
 208           { "Message Age",                  "dec_stp.msg_age",
 209             FT_UINT8,       BASE_DEC,       NULL,   0x0,
 210             NULL, HFILL }},
 211         { &hf_dec_bpdu_hello_time,
 212           { "Hello Time",                   "dec_stp.hello",
 213             FT_UINT8,       BASE_DEC,       NULL,   0x0,
 214             NULL, HFILL }},
 215         { &hf_dec_bpdu_max_age,
 216           { "Max Age",                      "dec_stp.max_age",
 217             FT_UINT8,       BASE_DEC,       NULL,   0x0,
 218             NULL, HFILL }},
 219         { &hf_dec_bpdu_forward_delay,
 220           { "Forward Delay",                "dec_stp.forward",
 221             FT_UINT8,       BASE_DEC,       NULL,   0x0,
 222             NULL, HFILL }},
 223     };
 224     static int *ett[] = {
 225         &ett_dec_bpdu,
 226         &ett_dec_bpdu_flags,
 227     };
 228
 229     proto_dec_bpdu = proto_register_protocol("DEC Spanning Tree Protocol",
 230                                              "DEC_STP", "dec_stp");
 231     proto_register_field_array(proto_dec_bpdu, hf, array_length(hf));
 232     proto_register_subtree_array(ett, array_length(ett));
 233
 234     dec_bpdu_handle = register_dissector("dec_stp", dissect_dec_bpdu,
 235                                               proto_dec_bpdu);
 236 }
 237
 238 void
 239 proto_reg_handoff_dec_bpdu(void)
 240 {
 241     dissector_add_uint("ethertype", ETHERTYPE_DEC_LB, dec_bpdu_handle);
 242     dissector_add_uint("chdlc.protocol", ETHERTYPE_DEC_LB, dec_bpdu_handle);
 243     dissector_add_uint("ppp.protocol", PPP_DEC_LB, dec_bpdu_handle);
 244 }
 245
 246 /*
 247  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
 248  *
 249  * Local variables:
 250  * c-basic-offset: 4
 251  * tab-width: 8
 252  * indent-tabs-mode: nil
 253  * End:
 254  *
 255  * vi: set shiftwidth=4 tabstop=8 expandtab:
 256  * :indentSize=4:tabSize=8:noTabs=true:
 257  */