/* packet-dec-bpdu.c

 * Routines for DEC BPDU (DEC Spanning Tree Protocol) disassembly

 *

 * Copyright 2001 Paul Ionescu <paul@acorp.ro>

 *

 * Wireshark - Network traffic analyzer

 * By Gerald Combs <gerald@wireshark.org>

 * Copyright 1998 Gerald Combs

 *

 * SPDX-License-Identifier: GPL-2.0-or-later

 */

#include "config.h"

#include <epan/packet.h>

#include <epan/etypes.h>

#include <epan/ppptypes.h>

#include <epan/tfs.h>

/* Offsets of fields within a BPDU */

#define BPDU_DEC_CODE            0

#define BPDU_TYPE                1

#define BPDU_VERSION             2

#define BPDU_FLAGS               3

#define BPDU_ROOT_PRI            4

#define BPDU_ROOT_MAC            6

#define BPDU_ROOT_PATH_COST     12

#define BPDU_BRIDGE_PRI         14

#define BPDU_BRIDGE_MAC         16

#define BPDU_PORT_IDENTIFIER    22

#define BPDU_MESSAGE_AGE        23

#define BPDU_HELLO_TIME         24

#define BPDU_MAX_AGE            25

#define BPDU_FORWARD_DELAY      26

#define DEC_BPDU_SIZE           27

/* Flag bits */

#define BPDU_FLAGS_SHORT_TIMERS         0x80

#define BPDU_FLAGS_TCACK                0x02

#define BPDU_FLAGS_TC                   0x01

void proto_register_dec_bpdu(void);

void proto_reg_handoff_dec_bpdu(void);

static dissector_handle_t dec_bpdu_handle;

static int proto_dec_bpdu;

static int hf_dec_bpdu_proto_id;

static int hf_dec_bpdu_type;

static int hf_dec_bpdu_version_id;

static int hf_dec_bpdu_flags;

static int hf_dec_bpdu_flags_short_timers;

static int hf_dec_bpdu_flags_tcack;

static int hf_dec_bpdu_flags_tc;

static int hf_dec_bpdu_root_pri;

static int hf_dec_bpdu_root_mac;

static int hf_dec_bpdu_root_cost;

static int hf_dec_bpdu_bridge_pri;

static int hf_dec_bpdu_bridge_mac;

static int hf_dec_bpdu_port_id;

static int hf_dec_bpdu_msg_age;

static int hf_dec_bpdu_hello_time;

static int hf_dec_bpdu_max_age;

static int hf_dec_bpdu_forward_delay;

static int ett_dec_bpdu;

static int ett_dec_bpdu_flags;

static const value_string protocol_id_vals[] = {

    { 0xe1, "DEC Spanning Tree Protocol" },

    { 0,    NULL }

};

#define BPDU_TYPE_TOPOLOGY_CHANGE       2

#define BPDU_TYPE_HELLO                 25

static const value_string bpdu_type_vals[] = {

    { BPDU_TYPE_TOPOLOGY_CHANGE, "Topology Change Notification" },

    { BPDU_TYPE_HELLO,           "Hello Packet" },

    { 0,                         NULL }

};

static int

dissect_dec_bpdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)

{

    uint8_t bpdu_type;

    proto_tree *bpdu_tree;

    proto_item *ti;

    static int * const bpdu_flags[] = {

        &hf_dec_bpdu_flags_short_timers,

        &hf_dec_bpdu_flags_tcack,

        &hf_dec_bpdu_flags_tc,

        NULL

    };

    col_set_str(pinfo->cinfo, COL_PROTOCOL, "DEC_STP");

    col_clear(pinfo->cinfo, COL_INFO);

    bpdu_type = tvb_get_uint8(tvb, BPDU_TYPE);

    col_add_str(pinfo->cinfo, COL_INFO,

                val_to_str(bpdu_type, bpdu_type_vals,

                           "Unknown BPDU type (%u)"));

    set_actual_length(tvb, DEC_BPDU_SIZE);

    if (tree) {

        ti = proto_tree_add_item(tree, proto_dec_bpdu, tvb, 0, DEC_BPDU_SIZE,

                                 ENC_NA);

        bpdu_tree = proto_item_add_subtree(ti, ett_dec_bpdu);

        proto_tree_add_item(bpdu_tree, hf_dec_bpdu_proto_id, tvb,

                            BPDU_DEC_CODE, 1, ENC_BIG_ENDIAN);

        proto_tree_add_uint(bpdu_tree, hf_dec_bpdu_type, tvb,

                            BPDU_TYPE, 1, bpdu_type);

        proto_tree_add_item(bpdu_tree, hf_dec_bpdu_version_id, tvb,

                            BPDU_VERSION, 1, ENC_BIG_ENDIAN);

        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);

        proto_tree_add_item(bpdu_tree, hf_dec_bpdu_root_pri, tvb,

                            BPDU_ROOT_PRI, 2, ENC_BIG_ENDIAN);

        proto_tree_add_item(bpdu_tree, hf_dec_bpdu_root_mac, tvb,

                            BPDU_ROOT_MAC, 6, ENC_NA);

        proto_tree_add_item(bpdu_tree, hf_dec_bpdu_root_cost, tvb,

                            BPDU_ROOT_PATH_COST, 2, ENC_BIG_ENDIAN);

        proto_tree_add_item(bpdu_tree, hf_dec_bpdu_bridge_pri, tvb,

                            BPDU_BRIDGE_PRI, 2, ENC_BIG_ENDIAN);

        proto_tree_add_item(bpdu_tree, hf_dec_bpdu_bridge_mac, tvb,

                            BPDU_BRIDGE_MAC, 6, ENC_NA);

        proto_tree_add_item(bpdu_tree, hf_dec_bpdu_port_id, tvb,

                            BPDU_PORT_IDENTIFIER, 1, ENC_BIG_ENDIAN);

        proto_tree_add_item(bpdu_tree, hf_dec_bpdu_msg_age, tvb,

                            BPDU_MESSAGE_AGE, 1, ENC_BIG_ENDIAN);

        proto_tree_add_item(bpdu_tree, hf_dec_bpdu_hello_time, tvb,

                            BPDU_HELLO_TIME, 1, ENC_BIG_ENDIAN);

        proto_tree_add_item(bpdu_tree, hf_dec_bpdu_max_age, tvb,

                            BPDU_MAX_AGE, 1, ENC_BIG_ENDIAN);

        proto_tree_add_item(bpdu_tree, hf_dec_bpdu_forward_delay, tvb,

                            BPDU_FORWARD_DELAY, 1, ENC_BIG_ENDIAN);

    }

    return tvb_captured_length(tvb);

}

void

proto_register_dec_bpdu(void)

{

    static hf_register_info hf[] = {

        { &hf_dec_bpdu_proto_id,

          { "Protocol Identifier",          "dec_stp.protocol",

            FT_UINT8,       BASE_HEX,       VALS(protocol_id_vals), 0x0,

            NULL, HFILL }},

        { &hf_dec_bpdu_type,

          { "BPDU Type",                    "dec_stp.type",

            FT_UINT8,       BASE_DEC,       VALS(bpdu_type_vals),   0x0,

            NULL, HFILL }},

        { &hf_dec_bpdu_version_id,

          { "BPDU Version",                 "dec_stp.version",

            FT_UINT8,       BASE_DEC,       NULL,   0x0,

            NULL, HFILL }},

        { &hf_dec_bpdu_flags,

          { "BPDU flags",                   "dec_stp.flags",

            FT_UINT8,       BASE_HEX,       NULL,   0x0,

            NULL, HFILL }},

        { &hf_dec_bpdu_flags_short_timers,

          { "Use short timers",             "dec_stp.flags.short_timers",

            FT_BOOLEAN,     8,              TFS(&tfs_yes_no),       BPDU_FLAGS_SHORT_TIMERS,

            NULL, HFILL }},

        { &hf_dec_bpdu_flags_tcack,

          { "Topology Change Acknowledgment",  "dec_stp.flags.tcack",

            FT_BOOLEAN,     8,              TFS(&tfs_yes_no),       BPDU_FLAGS_TCACK,

            NULL, HFILL }},

        { &hf_dec_bpdu_flags_tc,

          { "Topology Change",              "dec_stp.flags.tc",

            FT_BOOLEAN,     8,              TFS(&tfs_yes_no),       BPDU_FLAGS_TC,

            NULL, HFILL }},

        { &hf_dec_bpdu_root_pri,

          { "Root Priority",                "dec_stp.root.pri",

            FT_UINT16,      BASE_DEC,       NULL,   0x0,

            NULL, HFILL }},

        { &hf_dec_bpdu_root_mac,

          { "Root MAC",                     "dec_stp.root.mac",

            FT_ETHER,       BASE_NONE,      NULL,   0x0,

            NULL, HFILL }},

        { &hf_dec_bpdu_root_cost,

          { "Root Path Cost",               "dec_stp.root.cost",

            FT_UINT16,      BASE_DEC,       NULL,   0x0,

            NULL, HFILL }},

        { &hf_dec_bpdu_bridge_pri,

          { "Bridge Priority",              "dec_stp.bridge.pri",

            FT_UINT16,      BASE_DEC,       NULL,   0x0,

            NULL, HFILL }},

        { &hf_dec_bpdu_bridge_mac,

          { "Bridge MAC",                   "dec_stp.bridge.mac",

            FT_ETHER,       BASE_NONE,      NULL,   0x0,

            NULL, HFILL }},

        { &hf_dec_bpdu_port_id,

          { "Port identifier",              "dec_stp.port",

            FT_UINT8,       BASE_DEC,       NULL,   0x0,

            NULL, HFILL }},

        { &hf_dec_bpdu_msg_age,

          { "Message Age",                  "dec_stp.msg_age",

            FT_UINT8,       BASE_DEC,       NULL,   0x0,

            NULL, HFILL }},

        { &hf_dec_bpdu_hello_time,

          { "Hello Time",                   "dec_stp.hello",

            FT_UINT8,       BASE_DEC,       NULL,   0x0,

            NULL, HFILL }},

        { &hf_dec_bpdu_max_age,

          { "Max Age",                      "dec_stp.max_age",

            FT_UINT8,       BASE_DEC,       NULL,   0x0,

            NULL, HFILL }},

        { &hf_dec_bpdu_forward_delay,

          { "Forward Delay",                "dec_stp.forward",

            FT_UINT8,       BASE_DEC,       NULL,   0x0,

            NULL, HFILL }},

    };

    static int *ett[] = {

        &ett_dec_bpdu,

        &ett_dec_bpdu_flags,

    };

    proto_dec_bpdu = proto_register_protocol("DEC Spanning Tree Protocol",

                                             "DEC_STP", "dec_stp");

    proto_register_field_array(proto_dec_bpdu, hf, array_length(hf));

    proto_register_subtree_array(ett, array_length(ett));

    dec_bpdu_handle = register_dissector("dec_stp", dissect_dec_bpdu,

                                              proto_dec_bpdu);

}

void

proto_reg_handoff_dec_bpdu(void)

{

    dissector_add_uint("ethertype", ETHERTYPE_DEC_LB, dec_bpdu_handle);

    dissector_add_uint("chdlc.protocol", ETHERTYPE_DEC_LB, dec_bpdu_handle);

    dissector_add_uint("ppp.protocol", PPP_DEC_LB, dec_bpdu_handle);

}

/*

 * Editor modelines  -  https://www.wireshark.org/tools/modelines.html

 *

 * Local variables:

 * c-basic-offset: 4

 * tab-width: 8

 * indent-tabs-mode: nil

 * End:

 *

 * vi: set shiftwidth=4 tabstop=8 expandtab:

 * :indentSize=4:tabSize=8:noTabs=true:

 */