/* packet-vrrp.c

 * Routines for the Virtual Router Redundancy Protocol (VRRP)

 *

 * VRRPv2: RFC3768 (superseeding RFC2338)

 * VRRPv3: RFC5798

 *

 * Heikki Vatiainen <hessu@cs.tut.fi>

 *

 * 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/in_cksum.h>

#include <epan/expert.h>

#include <epan/prefs.h>

#include <epan/iana-info.h>

void proto_register_vrrp(void);

void proto_reg_handoff_vrrp(void);

static dissector_handle_t vrrp_handle;

static int proto_vrrp;

static int ett_vrrp;

static int ett_vrrp_ver_type;

static int hf_vrrp_ver_type;

static int hf_vrrp_version;

static int hf_vrrp_type;

static int hf_vrrp_virt_rtr_id;

static int hf_vrrp_prio;

static int hf_vrrp_addr_count;

static int hf_vrrp_checksum;

static int hf_vrrp_checksum_status;

static int hf_vrrp_auth_type;

static int hf_vrrp_adver_int;

static int hf_vrrp_reserved_mbz;

static int hf_vrrp_short_adver_int;

static int hf_vrrp_ip;

static int hf_vrrp_ip6;

static int hf_vrrp_auth_string;

static int hf_vrrp_md5_auth_data;

static bool g_vrrp_v3_checksum_as_in_v2 = true;

static expert_field ei_vrrp_checksum;

#define VRRP_VERSION_MASK  0xf0

#define VRRP_TYPE_MASK     0x0f

#define VRRP_AUTH_DATA_LEN    8

#define VRRP_TYPE_ADVERTISEMENT 1

static const value_string vrrp_type_vals[] = {

    {VRRP_TYPE_ADVERTISEMENT, "Advertisement"},

    {0, NULL}

};

#define VRRP_AUTH_TYPE_NONE        0

#define VRRP_AUTH_TYPE_SIMPLE_TEXT 1

#define VRRP_AUTH_TYPE_IP_AUTH_HDR 2

#define VRRP_AUTH_TYPE_IP_MD5      254

static const value_string vrrp_auth_vals[] = {

    {VRRP_AUTH_TYPE_NONE,        "No Authentication"},

    {VRRP_AUTH_TYPE_SIMPLE_TEXT, "Simple Text Authentication [RFC 2338] / Reserved [RFC 3768]"},

    {VRRP_AUTH_TYPE_IP_AUTH_HDR, "IP Authentication Header [RFC 2338] / Reserved [RFC 3768]"},

    {VRRP_AUTH_TYPE_IP_MD5,      "Cisco VRRP MD5 authentication"},

    {0, NULL}

};

#define VRRP_PRIORITY_MASTER_STOPPING 0

/* Values between 1 and 254 inclusive are for backup VRRP routers */

#define VRRP_PRIORITY_DEFAULT 100

#define VRRP_PRIORITY_OWNER   255

static const value_string vrrp_prio_vals[] = {

    {VRRP_PRIORITY_MASTER_STOPPING,  "Current Master has stopped participating in VRRP"},

    {VRRP_PRIORITY_DEFAULT,          "Default priority for a backup VRRP router"},

    {VRRP_PRIORITY_OWNER,            "This VRRP router owns the virtual router's IP address(es)"},

    {0, NULL }

};

static int

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

{

    int         offset = 0;

    int         vrrp_len;

    uint8_t     ver_type;

    vec_t       cksum_vec[4];

    uint32_t    phdr[2];

    bool        is_ipv6;

    proto_item *ti, *tv;

    proto_tree *vrrp_tree, *ver_type_tree;

    uint8_t     priority, addr_count = 0, auth_type = VRRP_AUTH_TYPE_NONE;

    uint16_t    computed_cksum = 0;

    is_ipv6 = (pinfo->src.type == AT_IPv6);

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

    col_clear(pinfo->cinfo, COL_INFO);

    ver_type = tvb_get_uint8(tvb, 0);

    col_add_fstr(pinfo->cinfo, COL_INFO, "Announcement (v%u)",

            hi_nibble(ver_type));

    ti = proto_tree_add_item(tree, proto_vrrp, tvb, 0, -1, ENC_NA);

    vrrp_tree = proto_item_add_subtree(ti, ett_vrrp);

    priority = tvb_get_uint8(tvb, 2);

    addr_count = tvb_get_uint8(tvb, 3);

    tv = proto_tree_add_uint_format(vrrp_tree, hf_vrrp_ver_type,

            tvb, offset, 1, ver_type,

            "Version %u, Packet type %u (%s)",

            hi_nibble(ver_type), lo_nibble(ver_type),

            val_to_str_const(lo_nibble(ver_type), vrrp_type_vals, "Unknown"));

    ver_type_tree = proto_item_add_subtree(tv, ett_vrrp_ver_type);

    if(ver_type_tree){

        proto_tree_add_uint(ver_type_tree, hf_vrrp_version, tvb,

                            offset, 1, ver_type);

        proto_tree_add_uint(ver_type_tree, hf_vrrp_type, tvb, offset, 1, ver_type);

        offset += 1;

        proto_tree_add_item(vrrp_tree, hf_vrrp_virt_rtr_id, tvb, offset, 1, ENC_BIG_ENDIAN);

        offset += 1;

        proto_tree_add_uint_format_value(vrrp_tree, hf_vrrp_prio, tvb, offset, 1, priority, "%u (%s)",

                                   priority,

                                   val_to_str_const(priority, vrrp_prio_vals, "Non-default backup priority"));

        offset += 1;

        proto_tree_add_uint(vrrp_tree, hf_vrrp_addr_count, tvb,

                            offset, 1, addr_count);

        offset += 1;

        switch(hi_nibble(ver_type)) {

        case 3:

            /* 4 bits reserved (mbz) + 12 bits interval */

            proto_tree_add_item(vrrp_tree, hf_vrrp_reserved_mbz, tvb, offset, 1, ENC_BIG_ENDIAN);

            proto_tree_add_item(vrrp_tree, hf_vrrp_short_adver_int, tvb, offset, 2, ENC_BIG_ENDIAN);

            offset += 2;

            break;

        case 2:

        default:

            /* 1 byte auth type + 1 byte interval */

            proto_tree_add_item_ret_uint8(vrrp_tree, hf_vrrp_auth_type, tvb, offset, 1, ENC_BIG_ENDIAN, &auth_type);

            offset += 1;

            proto_tree_add_item(vrrp_tree, hf_vrrp_adver_int, tvb, offset, 1, ENC_BIG_ENDIAN);

            offset += 1;

            break;

        }

    }else{

        offset += 6;

    }

    vrrp_len = (int)tvb_reported_length(tvb);

    if (!pinfo->fragmented && (int)tvb_captured_length(tvb) >= vrrp_len) {

        /* The packet isn't part of a fragmented datagram

           and isn't truncated, so we can checksum it. */

        switch(hi_nibble(ver_type)) {

            case 3:

                if((g_vrrp_v3_checksum_as_in_v2 == false)||(pinfo->src.type == AT_IPv6)){

                    /* Set up the fields of the pseudo-header. */

                    SET_CKSUM_VEC_PTR(cksum_vec[0], (const uint8_t *)pinfo->src.data, pinfo->src.len);

                    SET_CKSUM_VEC_PTR(cksum_vec[1], (const uint8_t *)pinfo->dst.data, pinfo->dst.len);

                    phdr[0] = g_htonl(vrrp_len);

                    phdr[1] = g_htonl(IP_PROTO_VRRP);

                    SET_CKSUM_VEC_PTR(cksum_vec[2], (const uint8_t *)&phdr, 8);

                    SET_CKSUM_VEC_TVB(cksum_vec[3], tvb, 0, vrrp_len);

                    computed_cksum = in_cksum(cksum_vec, 4);

                    break;

                }

            /* FALL THROUGH */

            case 2:

            default:

                SET_CKSUM_VEC_TVB(cksum_vec[0], tvb, 0, vrrp_len);

                computed_cksum = in_cksum(&cksum_vec[0], 1);

                break;

        }

        proto_tree_add_checksum(vrrp_tree, tvb, offset, hf_vrrp_checksum, hf_vrrp_checksum_status, &ei_vrrp_checksum, pinfo, computed_cksum,

                                ENC_BIG_ENDIAN, PROTO_CHECKSUM_VERIFY|PROTO_CHECKSUM_IN_CKSUM);

    } else {

        proto_tree_add_checksum(vrrp_tree, tvb, offset, hf_vrrp_checksum, hf_vrrp_checksum_status, &ei_vrrp_checksum, pinfo, 0,

                                ENC_BIG_ENDIAN, PROTO_CHECKSUM_NO_FLAGS);

    }

    offset += 2;

    while (addr_count > 0) {

        if (is_ipv6) {

            proto_tree_add_item(vrrp_tree, hf_vrrp_ip6, tvb, offset, 16, ENC_NA);

            offset += 16;

        } else {

            proto_tree_add_item(vrrp_tree, hf_vrrp_ip, tvb, offset, 4, ENC_BIG_ENDIAN);

            offset += 4;

        }

        addr_count--;

    }

    if (auth_type == VRRP_AUTH_TYPE_SIMPLE_TEXT) {

        proto_tree_add_item(vrrp_tree, hf_vrrp_auth_string, tvb, offset, VRRP_AUTH_DATA_LEN, ENC_ASCII);

        offset += VRRP_AUTH_DATA_LEN;

    } else if (auth_type == VRRP_AUTH_TYPE_IP_MD5) {

        if (vrrp_len - offset >= 16) {

            proto_tree_add_item(vrrp_tree, hf_vrrp_md5_auth_data, tvb, vrrp_len - 16, 16, ENC_NA);

        }

    }

    return offset;

}

void proto_register_vrrp(void)

{

    static hf_register_info hf[] = {

        { &hf_vrrp_ver_type,

            {"VRRP message version and type", "vrrp.typever",

                FT_UINT8, BASE_DEC, NULL, 0x0,

                NULL, HFILL }},

        { &hf_vrrp_version,

            {"VRRP protocol version", "vrrp.version",

                FT_UINT8, BASE_DEC, NULL, VRRP_VERSION_MASK,

                NULL, HFILL }},

        { &hf_vrrp_type,

            {"VRRP packet type", "vrrp.type",

                FT_UINT8, BASE_DEC, VALS(vrrp_type_vals), VRRP_TYPE_MASK,

                NULL, HFILL }},

        { &hf_vrrp_virt_rtr_id,

            {"Virtual Rtr ID", "vrrp.virt_rtr_id",

                FT_UINT8, BASE_DEC, NULL, 0x0,

                "Virtual router this packet is reporting status for", HFILL }},

        { &hf_vrrp_prio,

            {"Priority", "vrrp.prio",

                FT_UINT8, BASE_DEC, NULL, 0x0,

                "Sending VRRP router's priority for the virtual router", HFILL }},

        { &hf_vrrp_addr_count,

            {"Addr Count", "vrrp.addr_count",

                FT_UINT8, BASE_DEC, NULL, 0x0,

                "The number of addresses contained in this VRRP advertisement", HFILL }},

        { &hf_vrrp_checksum,

            { "Checksum", "vrrp.checksum",

                FT_UINT16, BASE_HEX, NULL, 0x0,

                "Used to detect data corruption in the VRRP message", HFILL }},

        { &hf_vrrp_checksum_status,

          { "Checksum Status", "vrrp.checksum.status",

                FT_UINT8, BASE_NONE, VALS(proto_checksum_vals), 0x0,

                NULL, HFILL }},

        { &hf_vrrp_auth_type,

            {"Auth Type", "vrrp.auth_type",

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

                "The authentication method being utilized", HFILL }},

        { &hf_vrrp_adver_int,

            {"Adver Int", "vrrp.adver_int",

                FT_UINT8, BASE_DEC, NULL, 0x0,

                "Time interval (in seconds) between ADVERTISEMENTS", HFILL }},

        { &hf_vrrp_reserved_mbz,

            {"Reserved", "vrrp.reserved_mbz",

                FT_UINT8, BASE_DEC, NULL, 0xF0,

                "Must be zero", HFILL }},

        { &hf_vrrp_short_adver_int,

            {"Adver Int", "vrrp.short_adver_int",

                FT_UINT16, BASE_DEC, NULL, 0x0FFF,

                "Time interval (in centiseconds) between ADVERTISEMENTS", HFILL }},

        { &hf_vrrp_ip,

            {"IP Address", "vrrp.ip_addr",

                FT_IPv4, BASE_NONE, NULL, 0x0,

                "IP address associated with the virtual router", HFILL }},

        { &hf_vrrp_ip6,

            {"IPv6 Address", "vrrp.ipv6_addr",

                FT_IPv6, BASE_NONE, NULL, 0x0,

                "IPv6 address associated with the virtual router", HFILL }},

        { &hf_vrrp_auth_string,

            {"Authentication String", "vrrp.auth_string",

                FT_STRING, BASE_NONE, NULL, 0x0,

                NULL, HFILL }},

        { &hf_vrrp_md5_auth_data,

            {"MD5 Authentication Data", "vrrp.md5_auth_data",

                FT_BYTES, BASE_NONE, NULL, 0x0,

                "MD5 digest string is contained.", HFILL }},

    };

    static int *ett[] = {

        &ett_vrrp,

        &ett_vrrp_ver_type

    };

    static ei_register_info ei[] = {

        { &ei_vrrp_checksum, { "vrrp.checksum_bad.expert", PI_CHECKSUM, PI_WARN, "Bad checksum", EXPFILL }},

    };

    expert_module_t* expert_vrrp;

    module_t *vrrp_module;

    proto_vrrp = proto_register_protocol("Virtual Router Redundancy Protocol", "VRRP", "vrrp");

    proto_register_field_array(proto_vrrp, hf, array_length(hf));

    proto_register_subtree_array(ett, array_length(ett));

    vrrp_handle = register_dissector("vrrp", dissect_vrrp, proto_vrrp);

    expert_vrrp = expert_register_protocol(proto_vrrp);

    expert_register_field_array(expert_vrrp, ei, array_length(ei));

    vrrp_module = prefs_register_protocol(proto_vrrp, NULL);

    prefs_register_bool_preference(vrrp_module, "v3_checksum_as_in_v2",

        "Calculate V3 checksum as in V2 for IPv4 packets",

        "There was some ambiguity on how to calculate IPv4 V3 checksums. "

        "As in v2 will not use a pseudo header (some manufacturers add a pseudo header for IPv4 checksum "

        "since RFC5798 was ambiguous). RFC9568 specifies that there is no pseudo header for IPv4.",

        &g_vrrp_v3_checksum_as_in_v2);

}

void

proto_reg_handoff_vrrp(void)

{

    dissector_add_uint("ip.proto", IP_PROTO_VRRP, vrrp_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:

 */