/* packet-gmrp.c
 * Routines for GMRP (GARP Multicast Registration Protocol) dissection
 * Copyright 2001, Markus Seehofer <mseehofe@nt.hirschmann.de>
 *
 * Based on the code from packet-gvrp.c (GVRP) from
 * Kevin Shi <techishi@ms22.hinet.net> Copyright 2000
 *
 * 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/expert.h>
#include <epan/llcsaps.h>

void proto_register_gmrp(void);

/* Initialize the protocol and registered fields */
static int proto_gmrp = -1;
static int hf_gmrp_proto_id = -1;
static int hf_gmrp_attribute_type = -1;
static int hf_gmrp_attribute_length = -1;
static int hf_gmrp_attribute_event = -1;
static int hf_gmrp_attribute_value_group_membership = -1;
static int hf_gmrp_attribute_value_service_requirement = -1;
static int hf_gmrp_end_of_mark = -1;

/* Initialize the subtree pointers */
static gint ett_gmrp = -1;
static gint ett_gmrp_message = -1;
static gint ett_gmrp_attribute_list = -1;
/*static gint ett_gmrp_attribute = -1;*/

static expert_field ei_gmrp_proto_id = EI_INIT;


/* Constant definitions */
#define GARP_DEFAULT_PROTOCOL_ID    0x0001
#define GARP_END_OF_MARK            0x00

#define GMRP_ATTRIBUTE_TYPE_GROUP_MEMBERSHIP    0x01
#define GMRP_ATTRIBUTE_TYPE_SERVICE_REQUIREMENT 0x02

#define GMRP_SERVICE_REQUIREMENT_FORWARD_ALL                0x00
#define GMRP_SERVICE_REQUIREMENT_FORWARD_ALL_UNREGISTERED   0x01

static const value_string attribute_type_vals[] = {
    { GMRP_ATTRIBUTE_TYPE_GROUP_MEMBERSHIP    ,"Group Membership" },
    { GMRP_ATTRIBUTE_TYPE_SERVICE_REQUIREMENT ,"Service Requirement" },
    { 0,                   NULL }
};

/* The length of GMRP LeaveAll attribute should be 2 octets (one for length
 * and the other for event) */
#define GMRP_LENGTH_LEAVEALL        (int)(sizeof(guint8)+sizeof(guint8))

/* The length of GMRP attribute other than LeaveAll should be:
*
*  8 bytes for Group Membership (1 for length, 1 for event and 6 for mac address to register)
*  or
*  3 bytes for Service Requirement (1 for length, 1 for event, 1 for attribute value)
*
 */
#define GMRP_GROUP_MEMBERSHIP_NON_LEAVEALL      (int)(sizeof(guint8)+sizeof(guint8)+(6*sizeof(guint8)))
#define GMRP_SERVICE_REQUIREMENT_NON_LEAVEALL   (int)(sizeof(guint8)+sizeof(guint8)+sizeof(guint8))

/* Packet offset definitions */
#define GARP_PROTOCOL_ID        0

/* Event definitions */
#define GMRP_EVENT_LEAVEALL     0
#define GMRP_EVENT_JOINEMPTY    1
#define GMRP_EVENT_JOININ       2
#define GMRP_EVENT_LEAVEEMPTY   3
#define GMRP_EVENT_LEAVEIN      4
#define GMRP_EVENT_EMPTY        5

static const value_string event_vals[] = {
    { GMRP_EVENT_LEAVEALL,   "Leave All" },
    { GMRP_EVENT_JOINEMPTY,  "Join Empty" },
    { GMRP_EVENT_JOININ,     "Join In" },
    { GMRP_EVENT_LEAVEEMPTY, "Leave Empty" },
    { GMRP_EVENT_LEAVEIN,    "Leave In" },
    { GMRP_EVENT_EMPTY,      "Empty" },
    { 0,                     NULL }
};


/* Code to actually dissect the packets */
static int
dissect_gmrp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
    proto_item   *ti;
    proto_tree   *gmrp_tree, *msg_tree, *attr_tree;
    guint16       protocol_id;
    guint8        octet;
    guint8        attribute_type;
    int           msg_index, attr_index, offset = 0, length = tvb_reported_length(tvb);

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

    col_set_str(pinfo->cinfo, COL_INFO, "GMRP");

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

        gmrp_tree = proto_item_add_subtree(ti, ett_gmrp);

        /* Read in GARP protocol ID */
        protocol_id = tvb_get_ntohs(tvb, GARP_PROTOCOL_ID);

        ti = proto_tree_add_uint_format_value(gmrp_tree, hf_gmrp_proto_id, tvb,
                                   GARP_PROTOCOL_ID, 2, protocol_id,
                                   "0x%04x (%s)", protocol_id,
                                   protocol_id == GARP_DEFAULT_PROTOCOL_ID ?
                                     "GARP Multicast Registration Protocol" :
                                     "Unknown Protocol");

        /* Currently only one protocol ID is supported */
        if (protocol_id != GARP_DEFAULT_PROTOCOL_ID)
        {
            expert_add_info(pinfo, ti, &ei_gmrp_proto_id);
            call_data_dissector(tvb_new_subset_remaining(tvb, GARP_PROTOCOL_ID + 2),
                pinfo, tree);
            return tvb_captured_length(tvb);
        }

        offset += 2;
        length -= 2;

        msg_index = 0;

        /* Begin to parse GARP messages */
        while (length)
        {
            proto_item   *msg_item;
            int           msg_start = offset;

            /* Read in attribute type. */
            attribute_type = octet = tvb_get_guint8(tvb, offset);

            /* Check for end of mark */
            if (octet == GARP_END_OF_MARK)
            {
                /* End of GARP PDU */
                if (msg_index)
                {
                    proto_tree_add_uint_format(gmrp_tree, hf_gmrp_end_of_mark, tvb, offset, 1, octet, "End of pdu");
                    break;
                }
                else
                {
                    call_data_dissector(tvb_new_subset_remaining(tvb, offset),
                                   pinfo, tree);
                    return tvb_captured_length(tvb);
                }
            }

            offset += 1;
            length -= 1;

            msg_tree = proto_tree_add_subtree_format(gmrp_tree, tvb, msg_start, -1,
                                           ett_gmrp_message, &msg_item, "Message %d", msg_index + 1);

            proto_tree_add_uint(msg_tree, hf_gmrp_attribute_type, tvb,
                                msg_start, 1, octet);

            /* GMRP supports Group Membership and Service Requirement as attribute types */
            if ( (octet != GMRP_ATTRIBUTE_TYPE_GROUP_MEMBERSHIP) && (octet != GMRP_ATTRIBUTE_TYPE_SERVICE_REQUIREMENT) )
            {
                call_data_dissector(tvb_new_subset_remaining(tvb, offset), pinfo,
                               tree);
                return tvb_captured_length(tvb);
            }

            attr_index = 0;

            while (length)
            {
                int          attr_start = offset;
                proto_item   *attr_item;

                /* Read in attribute length. */
                octet = tvb_get_guint8(tvb, offset);

                /* Check for end of mark */
                if (octet == GARP_END_OF_MARK)
                {
                    /* If at least one message has been already read,
                     * check for another end of mark.
                     */
                    if (attr_index)
                    {
                        proto_tree_add_uint_format(msg_tree, hf_gmrp_end_of_mark, tvb, offset,
                                            1, octet, "  End of mark");

                        offset += 1;
                        length -= 1;

                        proto_item_set_len(msg_item, offset - msg_start);
                        break;
                    }
                    else
                    {
                        call_data_dissector(tvb_new_subset_remaining(tvb, offset),
                                       pinfo, tree);
                        return tvb_captured_length(tvb);
                    }
                }
                else
                {
                    guint8   event;

                    offset += 1;
                    length -= 1;

                    attr_tree = proto_tree_add_subtree_format(msg_tree, tvb, attr_start, -1,
                                                    ett_gmrp_attribute_list, &attr_item, "  Attribute %d", attr_index + 1);

                    proto_tree_add_uint(attr_tree, hf_gmrp_attribute_length,
                                        tvb, attr_start, 1, octet);

                    /* Read in attribute event */
                    event = tvb_get_guint8(tvb, offset);

                    proto_tree_add_uint(attr_tree, hf_gmrp_attribute_event,
                                        tvb, offset, 1, event);

                    offset += 1;
                    length -= 1;

                    switch (event) {

                    case GMRP_EVENT_LEAVEALL:
                        if (octet != GMRP_LENGTH_LEAVEALL)
                        {
                            call_data_dissector(tvb_new_subset_remaining(tvb, offset),
                                           pinfo, tree);
                            return tvb_captured_length(tvb);
                        }
                        break;

                    case GMRP_EVENT_JOINEMPTY:
                    case GMRP_EVENT_JOININ:
                    case GMRP_EVENT_LEAVEEMPTY:
                    case GMRP_EVENT_LEAVEIN:
                    case GMRP_EVENT_EMPTY:
                        if ( (octet != GMRP_GROUP_MEMBERSHIP_NON_LEAVEALL) &&
                             (octet != GMRP_SERVICE_REQUIREMENT_NON_LEAVEALL) )
                        {
                            call_data_dissector(tvb_new_subset_remaining(tvb, offset),
                                           pinfo, tree);
                            return tvb_captured_length(tvb);
                        }

                        /* Show attribute value */

                        if ( GMRP_ATTRIBUTE_TYPE_GROUP_MEMBERSHIP == attribute_type )
                        {
                            /* Group Membership */
                            proto_tree_add_item(attr_tree, hf_gmrp_attribute_value_group_membership,
                                                tvb, offset, 6, ENC_NA);

                            offset += 6;
                            length -= 6;
                        }
                        else
                            if ( GMRP_ATTRIBUTE_TYPE_SERVICE_REQUIREMENT == attribute_type )
                            {
                                /* Service Requirement */
                                proto_tree_add_item(attr_tree, hf_gmrp_attribute_value_service_requirement,
                                                    tvb, offset, 1, ENC_BIG_ENDIAN);

                                offset += 1;
                                length -= 1;
                            }
                            else
                            {
                                call_data_dissector(tvb_new_subset_remaining(tvb, offset),
                                               pinfo, tree);
                                return tvb_captured_length(tvb);
                            }

                        break;

                    default:
                        call_data_dissector(tvb_new_subset_remaining(tvb, offset),
                                       pinfo, tree);
                        return tvb_captured_length(tvb);
                    }
                }

                proto_item_set_len(attr_item, offset - attr_start);

                attr_index++;
            }

            msg_index++;
        }
        return tvb_captured_length(tvb);
}



/* Register the protocol with Wireshark */
void
proto_register_gmrp(void)
{
    static hf_register_info hf[] = {
        { &hf_gmrp_proto_id,
          { "Protocol Identifier", "gmrp.protocol_id",
            FT_UINT16,      BASE_HEX,      NULL,  0x0,
            NULL , HFILL }
        },
        { &hf_gmrp_attribute_type,
          { "Type",        "gmrp.attribute_type",
            FT_UINT8,        BASE_HEX,      VALS(attribute_type_vals),  0x0,
            NULL , HFILL }
        },
        { &hf_gmrp_attribute_length,
          { "Length",      "gmrp.attribute_length",
            FT_UINT8,        BASE_DEC,      NULL,  0x0,
            NULL , HFILL }
        },
        { &hf_gmrp_attribute_event,
          { "Event",       "gmrp.attribute_event",
            FT_UINT8,        BASE_DEC,      VALS(event_vals),  0x0,
            NULL , HFILL }
        },
        { &hf_gmrp_attribute_value_group_membership,
          { "Value",       "gmrp.attribute_value_group_membership",
            FT_ETHER,        BASE_NONE,      NULL,  0x0,
            NULL , HFILL }
        },
        { &hf_gmrp_attribute_value_service_requirement,
          { "Value",       "gmrp.attribute_value_service_requirement",
            FT_UINT8,        BASE_HEX,      NULL,  0x0,
            NULL , HFILL }
        },
        { &hf_gmrp_end_of_mark,
          { "End of mark",       "gmrp.end_of_mark",
            FT_UINT8,        BASE_HEX,      NULL,  0x0,
            NULL , HFILL }
        }

    };

    static gint *ett[] = {
        &ett_gmrp,
        &ett_gmrp_message,
        &ett_gmrp_attribute_list
    };

    static ei_register_info ei[] = {
        { &ei_gmrp_proto_id, { "gmrp.protocol_id.not_gmrp", PI_UNDECODED, PI_WARN, "This version of Wireshark only knows about protocol id = 1", EXPFILL }},
    };

    expert_module_t* expert_gmrp;

    /* Register the protocol name and description for GMRP */
    proto_gmrp = proto_register_protocol("GARP Multicast Registration Protocol", "GMRP", "gmrp");

    /* Required function calls to register the header fields and subtrees
     * used by GMRP */
    proto_register_field_array(proto_gmrp, hf, array_length(hf));
    proto_register_subtree_array(ett, array_length(ett));
    expert_gmrp = expert_register_protocol(proto_gmrp);
    expert_register_field_array(expert_gmrp, ei, array_length(ei));

    register_dissector("gmrp", dissect_gmrp, proto_gmrp);

}

/*
 * 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:
 */
