path: root/epan/dissectors/packet-vrrp.c

/* 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/ipproto.h>
#include <epan/in_cksum.h>
#include <epan/expert.h>
#include <epan/prefs.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(vrrp_tree, hf_vrrp_prio, tvb, offset, 1, priority, "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 */
            auth_type = tvb_get_uint8(tvb, offset);
            proto_tree_add_item(vrrp_tree, hf_vrrp_auth_type, tvb, offset, 1, ENC_BIG_ENDIAN);
            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:
 */