/* packet-socketcan.c

 * Routines for disassembly of packets from SocketCAN

 * Felix Obenhuber <felix@obenhuber.de>

 *

 * Added support for the DeviceNet Dissector

 * Hans-Joergen Gunnarsson <hag@hms.se>

 * Copyright 2013

 *

 * 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/prefs.h>

#include <epan/expert.h>

#include <epan/decode_as.h>

#include <epan/uat.h>

#include <wiretap/wtap.h>

#include "packet-sll.h"

#include "packet-socketcan.h"

void proto_register_socketcan(void);

void proto_reg_handoff_socketcan(void);

static int hf_can_len;

static int hf_can_bus_id;

static int hf_can_infoent_ext;

static int hf_can_infoent_std;

static int hf_can_extflag;

static int hf_can_rtrflag;

static int hf_can_errflag;

static int hf_can_reserved;

static int hf_can_len8dlc;

static int hf_can_padding;

static int hf_can_err_tx_timeout;

static int hf_can_err_lostarb;

static int hf_can_err_ctrl;

static int hf_can_err_prot;

static int hf_can_err_trx;

static int hf_can_err_ack;

static int hf_can_err_busoff;

static int hf_can_err_buserror;

static int hf_can_err_restarted;

static int hf_can_err_reserved;

static int hf_can_err_lostarb_bit_number;

static int hf_can_err_ctrl_rx_overflow;

static int hf_can_err_ctrl_tx_overflow;

static int hf_can_err_ctrl_rx_warning;

static int hf_can_err_ctrl_tx_warning;

static int hf_can_err_ctrl_rx_passive;

static int hf_can_err_ctrl_tx_passive;

static int hf_can_err_ctrl_active;

static int hf_can_err_prot_error_type_bit;

static int hf_can_err_prot_error_type_form;

static int hf_can_err_prot_error_type_stuff;

static int hf_can_err_prot_error_type_bit0;

static int hf_can_err_prot_error_type_bit1;

static int hf_can_err_prot_error_type_overload;

static int hf_can_err_prot_error_type_active;

static int hf_can_err_prot_error_type_tx;

static int hf_can_err_prot_error_location;

static int hf_can_err_trx_canh;

static int hf_can_err_trx_canl;

static int hf_can_err_ctrl_specific;

static int hf_canxl_priority;

static int hf_canxl_vcid;

static int hf_canxl_secflag;

static int hf_canxl_rrsflag;

static int hf_canxl_xlflag;

static int hf_canxl_sdu_type;

static int hf_canxl_len;

static int hf_canxl_acceptance_field;

static expert_field ei_can_err_dlc_mismatch;

static int hf_canfd_brsflag;

static int hf_canfd_esiflag;

static int hf_canfd_fdflag;

static int ett_can;

static int ett_can_fd;

static int ett_can_xl;

static int proto_can;

static int proto_canfd;

static int proto_canxl;

static bool byte_swap;

static bool heuristic_first;

static heur_dissector_list_t heur_subdissector_list;

static heur_dtbl_entry_t *heur_dtbl_entry;

#define LINUX_CAN_STD   0

#define LINUX_CAN_EXT   1

#define LINUX_CAN_ERR   2

#define CAN_LEN_OFFSET     4

#define CAN_DATA_OFFSET    8

#define CANFD_FLAG_OFFSET  5

#define CANXL_FLAGS_OFFSET CAN_LEN_OFFSET

#define CANXL_LEN_OFFSET   6

#define CANXL_DATA_OFFSET  12

static dissector_table_t can_id_dissector_table;

static dissector_table_t can_extended_id_dissector_table;

static dissector_table_t subdissector_table;

static dissector_table_t canxl_sdu_type_dissector_table;

static dissector_handle_t socketcan_classic_handle;

static dissector_handle_t socketcan_fd_handle;

static dissector_handle_t socketcan_xl_handle;

static dissector_handle_t socketcan_bigendian_handle;

static const value_string can_err_prot_error_location_vals[] = {

    { 0x00, "unspecified" },

    { 0x02, "ID bits 28 - 21 (SFF: 10 - 3)" },

    { 0x03, "start of frame" },

    { 0x04, "substitute RTR (SFF: RTR)" },

    { 0x05, "identifier extension" },

    { 0x06, "ID bits 20 - 18 (SFF: 2 - 0)" },

    { 0x07, "ID bits 17-13" },

    { 0x08, "CRC sequence" },

    { 0x09, "reserved bit 0" },

    { 0x0A, "data section" },

    { 0x0B, "data length code" },

    { 0x0C, "RTR" },

    { 0x0D, "reserved bit 1" },

    { 0x0E, "ID bits 4-0" },

    { 0x0F, "ID bits 12-5" },

    { 0x12, "intermission" },

    { 0x18, "CRC delimiter" },

    { 0x19, "ACK slot" },

    { 0x1A, "end of frame" },

    { 0x1B, "ACK delimiter" },

    { 0, NULL }

};

static const value_string can_err_trx_canh_vals[] = {

    { 0x00, "unspecified" },

    { 0x04, "no wire" },

    { 0x05, "short to BAT" },

    { 0x06, "short to VCC" },

    { 0x07, "short to GND" },

    { 0, NULL }

};

static const value_string can_err_trx_canl_vals[] = {

    { 0x00, "unspecified" },

    { 0x04, "no wire" },

    { 0x05, "short to BAT" },

    { 0x06, "short to VCC" },

    { 0x07, "short to GND" },

    { 0x08, "short to CANH" },

    { 0, NULL }

};

/********* UATs *********/

/* Interface Config UAT */

typedef struct _interface_config {

    unsigned   interface_id;

    char   *interface_name;

    unsigned   bus_id;

} interface_config_t;

#define DATAFILE_CAN_INTERFACE_MAPPING "CAN_interface_mapping"

static GHashTable *data_can_interfaces_by_id;

static GHashTable *data_can_interfaces_by_name;

static interface_config_t *interface_configs;

static unsigned interface_config_num;

UAT_HEX_CB_DEF(interface_configs, interface_id, interface_config_t)

Unexecuted instantiation: packet-socketcan.c:interface_configs_interface_id_set_cb

Unexecuted instantiation: packet-socketcan.c:interface_configs_interface_id_tostr_cb

UAT_CSTRING_CB_DEF(interface_configs, interface_name, interface_config_t)

UAT_HEX_CB_DEF(interface_configs, bus_id, interface_config_t)

Unexecuted instantiation: packet-socketcan.c:interface_configs_bus_id_set_cb

Unexecuted instantiation: packet-socketcan.c:interface_configs_bus_id_tostr_cb

static void *

copy_interface_config_cb(void *n, const void *o, size_t size _U_) {

    interface_config_t *new_rec = (interface_config_t *)n;

    const interface_config_t *old_rec = (const interface_config_t *)o;

    new_rec->interface_id = old_rec->interface_id;

    new_rec->interface_name = g_strdup(old_rec->interface_name);

    new_rec->bus_id = old_rec->bus_id;

    return new_rec;

}

static bool

update_interface_config(void *r, char **err) {

    interface_config_t *rec = (interface_config_t *)r;

    if (rec->interface_id > 0xffffffff) {

        *err = ws_strdup_printf("We currently only support 32 bit identifiers (ID: %i  Name: %s)",

                                rec->interface_id, rec->interface_name);

        return false;

    }

    if (rec->bus_id > 0xffff) {

        *err = ws_strdup_printf("We currently only support 16 bit bus identifiers (ID: %i  Name: %s  Bus-ID: %i)",

                                rec->interface_id, rec->interface_name, rec->bus_id);

        return false;

    }

    return true;

}

static void

free_interface_config_cb(void *r) {

    interface_config_t *rec = (interface_config_t *)r;

    /* freeing result of g_strdup */

    g_free(rec->interface_name);

    rec->interface_name = NULL;

}

static void

post_update_can_interfaces_cb(void) {

    unsigned  i;

    /* destroy old hash tables, if they exist */

    if (data_can_interfaces_by_id) {

        g_hash_table_destroy(data_can_interfaces_by_id);

    }

    if (data_can_interfaces_by_name) {

        g_hash_table_destroy(data_can_interfaces_by_name);

    }

    /* create new hash table */

    data_can_interfaces_by_id = g_hash_table_new_full(g_direct_hash, g_direct_equal, NULL, NULL);

    data_can_interfaces_by_name = g_hash_table_new_full(g_str_hash, g_str_equal, NULL, NULL);

    for (i = 0; i < interface_config_num; i++) {

        if (interface_configs[i].interface_id != 0xfffffff) {

            g_hash_table_insert(data_can_interfaces_by_id, GUINT_TO_POINTER(interface_configs[i].interface_id), &interface_configs[i]);

        }

        if (interface_configs[i].interface_name != NULL && interface_configs[i].interface_name[0] != 0) {

            g_hash_table_insert(data_can_interfaces_by_name, interface_configs[i].interface_name, &interface_configs[i]);

        }

    }

}

static void

reset_can_interfaces_cb(void) {

    if (data_can_interfaces_by_id) {

        g_hash_table_destroy(data_can_interfaces_by_id);

        data_can_interfaces_by_id = NULL;

    }

    if (data_can_interfaces_by_name) {

        g_hash_table_destroy(data_can_interfaces_by_name);

        data_can_interfaces_by_name = NULL;

    }

}

/* We match based on the config in the following order:

 * - interface_name matches and interface_id matches

 * - interface_name matches and interface_id = 0xffffffff

 * - interface_name = ""    and interface_id matches

 */

static unsigned

get_bus_id_common(const char* interface_name, uint32_t interface_id) {

    if (interface_name != NULL && interface_name[0] != 0) {

        interface_config_t* tmp = NULL;

        if (data_can_interfaces_by_name != NULL) {

            tmp = g_hash_table_lookup(data_can_interfaces_by_name, interface_name);

            if (tmp != NULL && (tmp->interface_id == 0xffffffff || tmp->interface_id == interface_id)) {

                /* name + id match or name match and id = any */

                return tmp->bus_id;

            }

        }

        if (data_can_interfaces_by_id != NULL) {

            tmp = g_hash_table_lookup(data_can_interfaces_by_id, GUINT_TO_POINTER(interface_id));

            if (tmp != NULL && (tmp->interface_name == NULL || tmp->interface_name[0] == 0)) {

                /* id matches and name is any */

                return tmp->bus_id;

            }

        }

    }

    /* we found nothing */

    return 0;

}

static unsigned

get_bus_id(packet_info *pinfo) {

    if (!(pinfo->rec->presence_flags & WTAP_HAS_INTERFACE_ID)) {

        return 0;

    }

    uint32_t    interface_id = pinfo->rec->rec_header.packet_header.interface_id;

    unsigned    section_number = pinfo->rec->presence_flags & WTAP_HAS_SECTION_NUMBER ? pinfo->rec->section_number : 0;

    const char* interface_name = epan_get_interface_name(pinfo->epan, interface_id, section_number);

    return get_bus_id_common(interface_name, interface_id);

}

unsigned

can_get_bus_id_from_interface_name(const char* interface_name) {

    return get_bus_id_common(interface_name, 0xffffffff);

}

/* Senders and Receivers UAT */

typedef struct _sender_receiver_config {

    unsigned   bus_id;

    unsigned   can_id;

    char   *sender_name;

    char   *receiver_name;

} sender_receiver_config_t;

#define DATAFILE_CAN_SENDER_RECEIVER "CAN_senders_receivers"

static GHashTable *data_sender_receiver;

static sender_receiver_config_t *sender_receiver_configs;

static unsigned sender_receiver_config_num;

UAT_HEX_CB_DEF(sender_receiver_configs, bus_id, sender_receiver_config_t)

Unexecuted instantiation: packet-socketcan.c:sender_receiver_configs_bus_id_set_cb

Unexecuted instantiation: packet-socketcan.c:sender_receiver_configs_bus_id_tostr_cb

UAT_HEX_CB_DEF(sender_receiver_configs, can_id, sender_receiver_config_t)

Unexecuted instantiation: packet-socketcan.c:sender_receiver_configs_can_id_set_cb

Unexecuted instantiation: packet-socketcan.c:sender_receiver_configs_can_id_tostr_cb

UAT_CSTRING_CB_DEF(sender_receiver_configs, sender_name, sender_receiver_config_t)

UAT_CSTRING_CB_DEF(sender_receiver_configs, receiver_name, sender_receiver_config_t)

static void *

copy_sender_receiver_config_cb(void *n, const void *o, size_t size _U_) {

    sender_receiver_config_t *new_rec = (sender_receiver_config_t *)n;

    const sender_receiver_config_t *old_rec = (const sender_receiver_config_t *)o;

    new_rec->bus_id = old_rec->bus_id;

    new_rec->can_id = old_rec->can_id;

    new_rec->sender_name = g_strdup(old_rec->sender_name);

    new_rec->receiver_name = g_strdup(old_rec->receiver_name);

    return new_rec;

}

static bool

update_sender_receiver_config(void *r, char **err) {

    sender_receiver_config_t *rec = (sender_receiver_config_t *)r;

    if (rec->bus_id > 0xffff) {

        *err = ws_strdup_printf("We currently only support 16 bit bus identifiers (Bus ID: %i  CAN ID: %i)", rec->bus_id, rec->can_id);

        return false;

    }

    return true;

}

static void

free_sender_receiver_config_cb(void *r) {

    sender_receiver_config_t *rec = (sender_receiver_config_t *)r;

    /* freeing result of g_strdup */

    g_free(rec->sender_name);

    rec->sender_name = NULL;

    g_free(rec->receiver_name);

    rec->receiver_name = NULL;

}

static uint64_t

sender_receiver_key(uint16_t bus_id, uint32_t can_id) {

    return ((uint64_t)bus_id << 32) | can_id;

}

static sender_receiver_config_t *

ht_lookup_sender_receiver_config(uint16_t bus_id, uint32_t can_id) {

    uint64_t key;

    sender_receiver_config_t* tmp;

    if (data_sender_receiver == NULL) {

        return NULL;

    }

    key = sender_receiver_key(bus_id, can_id);

    tmp = g_hash_table_lookup(data_sender_receiver, &key);

    if (tmp == NULL) {

        key = sender_receiver_key(0, can_id);

        tmp = g_hash_table_lookup(data_sender_receiver, &key);

    }

    return tmp;

}

static void

post_update_sender_receiver_cb(void) {

    unsigned i;

    uint64_t *key;

    /* destroy old hash table, if it exist */

    if (data_sender_receiver) {

        g_hash_table_destroy(data_sender_receiver);

    }

    /* create new hash table */

    data_sender_receiver = g_hash_table_new_full(g_int64_hash, g_int64_equal, g_free, NULL);

    for (i = 0; i < sender_receiver_config_num; i++) {

        key = g_new(uint64_t, 1);

        *key = sender_receiver_key(sender_receiver_configs[i].bus_id, sender_receiver_configs[i].can_id);

        g_hash_table_insert(data_sender_receiver, key, &sender_receiver_configs[i]);

    }

}

static void

reset_sender_receiver_cb(void) {

    /* destroy hash table, if it exists */

    if (data_sender_receiver) {

        g_hash_table_destroy(data_sender_receiver);

        data_sender_receiver = NULL;

    }

}

bool

socketcan_set_source_and_destination_columns(packet_info *pinfo, can_info_t *caninfo) {

    sender_receiver_config_t *tmp = ht_lookup_sender_receiver_config(caninfo->bus_id, caninfo->id);

    if (tmp != NULL) {

        /* remove all addresses to support CAN as payload (e.g., TECMP) */

        clear_address(&pinfo->net_src);

        clear_address(&pinfo->dl_src);

        clear_address(&pinfo->src);

        clear_address(&pinfo->net_dst);

        clear_address(&pinfo->dl_dst);

        clear_address(&pinfo->dst);

        col_add_str(pinfo->cinfo, COL_DEF_SRC, tmp->sender_name);

        col_add_str(pinfo->cinfo, COL_DEF_DST, tmp->receiver_name);

        return true;

    }

    return false;

}

bool

socketcan_call_subdissectors(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, struct can_info *can_info, const bool use_heuristics_first) {

    dissector_table_t effective_can_id_dissector_table = (can_info->id & CAN_EFF_FLAG) ? can_extended_id_dissector_table : can_id_dissector_table;

    uint32_t effective_can_id = (can_info->id & CAN_EFF_FLAG) ? can_info->id & CAN_EFF_MASK : can_info->id & CAN_SFF_MASK;

    if (!dissector_try_uint_with_data(effective_can_id_dissector_table, effective_can_id, tvb, pinfo, tree, true, can_info)) {

        if (!use_heuristics_first) {

            if (!dissector_try_payload_with_data(subdissector_table, tvb, pinfo, tree, true, can_info)) {

                if (!dissector_try_heuristic(heur_subdissector_list, tvb, pinfo, tree, &heur_dtbl_entry, can_info)) {

                    return false;

                }

            }

        } else {

            if (!dissector_try_heuristic(heur_subdissector_list, tvb, pinfo, tree, &heur_dtbl_entry, can_info)) {

                if (!dissector_try_payload_with_data(subdissector_table, tvb, pinfo, tree, false, can_info)) {

                    return false;

                }

            }

        }

    }

    return true;

}

/*

 * Either:

 *

 *    1) a given SocketCAN frame is known to contain a classic CAN

 *       packet based on information outside the SocketCAN header;

 *

 *    2) a given SocketCAN frame is known to contain a CAN FD

 *       packet based on information outside the SocketCAN header;

 *

 *    3) a given SocketCAN frame is known to contain a CAN XL

 *       packet based on information outside the SocketCAN header;

 *

 *    4) we don't know whether the given SocketCAN frame is a

 *       classic CAN packet, a CAN FD packet, or a CAN XL packet,

 *       and will have to check the CANXL_XLF bit in the "Frame Length"

 *       field and the CANFD_FDF bit in the "FD flags" field of the

 *       SocketCAN header to determine that.

 */

typedef enum {

    PACKET_TYPE_CAN,

    PACKET_TYPE_CAN_FD,

    PACKET_TYPE_CAN_XL,

    PACKET_TYPE_UNKNOWN

} can_packet_type_t;

static int

dissect_socketcan_common(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, unsigned encoding, unsigned xl_encoding, can_packet_type_t can_packet_type) {

    proto_tree     *can_tree;

    proto_item     *ti;

    uint8_t         frame_type;

    can_info_t      can_info;

    int * const    *can_flags_id;

    static int * const can_std_flags_id[] = {

        &hf_can_infoent_std,

        &hf_can_extflag,

        &hf_can_rtrflag,

        &hf_can_errflag,

        NULL,

    };

    static int * const can_ext_flags_id[] = {

        &hf_can_infoent_ext,

        &hf_can_extflag,

        &hf_can_rtrflag,

        &hf_can_errflag,

        NULL,

    };

    static int * const canfd_std_flags_id[] = {

        &hf_can_infoent_std,

        &hf_can_extflag,

        NULL,

    };

    static int * const canfd_ext_flags_id[] = {

        &hf_can_infoent_ext,

        &hf_can_extflag,

        NULL,

    };

    static int * const canfd_flag_fields[] = {

        &hf_canfd_brsflag,

        &hf_canfd_esiflag,

        &hf_canfd_fdflag,

        NULL,

    };

    static int * const can_err_flags[] = {

        &hf_can_errflag,

        &hf_can_err_tx_timeout,

        &hf_can_err_lostarb,

        &hf_can_err_ctrl,

        &hf_can_err_prot,

        &hf_can_err_trx,

        &hf_can_err_ack,

        &hf_can_err_busoff,

        &hf_can_err_buserror,

        &hf_can_err_restarted,

        &hf_can_err_reserved,

        NULL,

    };

    static int * const canxl_prio_vcid_fields[] = {

        &hf_canxl_priority,

        &hf_canxl_vcid,

        NULL,

    };

    static int * const canxl_flag_fields[] = {

        &hf_canxl_secflag,

        &hf_canxl_rrsflag,

        &hf_canxl_xlflag,

        NULL,

    };

    /* determine CAN packet type */

    if (can_packet_type == PACKET_TYPE_UNKNOWN) {

        uint8_t canfd_flags;

        uint8_t canxl_flags;

        /*

         * Check whether the frame has the CANXL_XLF flag set in what

         * is in the location of the frame length field of a CAN classic

         * or CAN FD frame; if so, then it's a CAN XL frame (and that

         * field is the flags field of that frame).

         */

        canfd_flags = tvb_get_uint8(tvb, CANFD_FLAG_OFFSET);

        canxl_flags = tvb_get_uint8(tvb, CANXL_FLAGS_OFFSET);

        if (canxl_flags & CANXL_XLF) {

            /* CAN XL: check for min/max data length */

            if (tvb_reported_length(tvb) >= 13 && tvb_reported_length(tvb) <= 2060) {

                can_packet_type = PACKET_TYPE_CAN_XL;

            } else {

                /* invalid CAN XL frame (expert info) */

                return tvb_captured_length(tvb);

            }

        } else {

            /* CAN CC/FD */

            if (tvb_reported_length(tvb) == 72 || (canfd_flags & CANFD_FDF)) {

                /* CAN FD: check for min/max data length */

                if (tvb_reported_length(tvb) >= 8 && tvb_reported_length(tvb) <= 72) {

                    can_packet_type = PACKET_TYPE_CAN_FD;

                } else {

                    /* invalid CAN FD frame (expert info) */

                    return tvb_captured_length(tvb);

                }

            } else if (tvb_reported_length(tvb) >= 8 && tvb_reported_length(tvb) <= 16) {

                can_packet_type = PACKET_TYPE_CAN;

            } else {

                /* invalid CAN CC frame (expert info) */

                return tvb_captured_length(tvb);

            }

        }

    }

    can_info.bus_id = get_bus_id(pinfo);

    if (can_packet_type == PACKET_TYPE_CAN_XL) {

        can_info.fd = CAN_TYPE_CAN_XL;

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

        col_clear(pinfo->cinfo, COL_INFO);

        can_info.id = 0; /* XXX - is there an "ID" for XL frames? */

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

        proto_item_set_hidden(ti);

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

        can_tree = proto_item_add_subtree(ti, ett_can_xl);

        if (can_info.bus_id != 0) {

            ti = proto_tree_add_uint(can_tree, hf_can_bus_id, tvb, 0, 0, can_info.bus_id);

            proto_item_set_hidden(ti);

        }

        uint32_t proto_vcid;

  /*

   * The priority/VCID field is big-endian in LINKTYPE_CAN_SOCKETCAN

   * captures, for historical reasons.  It's host-endian in

   * Linux cooked captures.  This means we use the non-XL encoding.

   */

        proto_tree_add_bitmask_list(can_tree, tvb, 0, 4, canxl_prio_vcid_fields, encoding);

        proto_vcid = tvb_get_uint32(tvb, 0, encoding);

        col_add_fstr(pinfo->cinfo, COL_INFO, "Priority: %u (0x%03x), VCID: %u (0x%02X)", proto_vcid & 0x7FF, proto_vcid & 0x7FF, (proto_vcid >> 16) & 0xFF, (proto_vcid >> 16) & 0xFF);

        proto_item_append_text(can_tree, ", Priority: %u (0x%03x), VCID: %u (0x%02X)", proto_vcid & 0x7FF, proto_vcid & 0x7FF, (proto_vcid >> 16) & 0xFF, (proto_vcid >> 16) & 0xFF);

        proto_tree_add_bitmask_list(can_tree, tvb, 4, 1, canxl_flag_fields, xl_encoding);

        socketcan_set_source_and_destination_columns(pinfo, &can_info);

        uint32_t sdu_type;

  /*

   * These fields are, if multi-byte, little-endian in

   * LINKTYPE_CAN_SOCKETCAN captures, so use xl_encoding.

   */

        proto_tree_add_item_ret_uint(can_tree, hf_canxl_sdu_type, tvb, 5, 1, ENC_NA, &sdu_type);

        proto_tree_add_item_ret_uint(can_tree, hf_canxl_len, tvb, CANXL_LEN_OFFSET, 2, xl_encoding, &can_info.len);

        col_append_fstr(pinfo->cinfo, COL_INFO, ", Length: %u", can_info.len);

        proto_item_append_text(can_tree, ", Length: %u", can_info.len);

        proto_tree_add_item(can_tree, hf_canxl_acceptance_field, tvb, CANXL_LEN_OFFSET+2, 4, xl_encoding);

        tvbuff_t   *next_tvb;

        next_tvb = tvb_new_subset_length(tvb, CANXL_DATA_OFFSET, can_info.len);

        if (!dissector_try_uint_with_data(canxl_sdu_type_dissector_table, sdu_type, next_tvb, pinfo, tree, true, &can_info)) {

            call_data_dissector(next_tvb, pinfo, tree);

        }

        if (tvb_captured_length_remaining(tvb, CANXL_DATA_OFFSET+can_info.len) > 0) {

            proto_tree_add_item(can_tree, hf_can_padding, tvb, CANXL_DATA_OFFSET+can_info.len, -1, ENC_NA);

        }

    } else {

        if (can_packet_type == PACKET_TYPE_CAN_FD) {

            can_info.fd = CAN_TYPE_CAN_FD;

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

        } else {

            can_info.fd = CAN_TYPE_CAN_CLASSIC;

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

        }

        col_clear(pinfo->cinfo, COL_INFO);

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

        if (can_packet_type == PACKET_TYPE_CAN_FD) {

            proto_item_set_hidden(ti);

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

        }

        can_tree = proto_item_add_subtree(ti, (can_packet_type == PACKET_TYPE_CAN_FD) ? ett_can_fd : ett_can);

        if (can_info.bus_id != 0) {

            ti = proto_tree_add_uint(can_tree, hf_can_bus_id, tvb, 0, 0, can_info.bus_id);

            proto_item_set_hidden(ti);

        }

        /* Get the ID and flags field */

        can_info.id = tvb_get_uint32(tvb, 0, encoding);

        /* Error Message Frames are only encapsulated in Classic CAN frames */

        if (can_packet_type == PACKET_TYPE_CAN && (can_info.id & CAN_ERR_FLAG)) {

            frame_type = LINUX_CAN_ERR;

            can_flags_id  = can_err_flags;

        } else if (can_info.id & CAN_EFF_FLAG) {

            frame_type = LINUX_CAN_EXT;

            can_info.id &= (CAN_EFF_MASK | CAN_FLAG_MASK);

            can_flags_id  = (can_packet_type == PACKET_TYPE_CAN_FD) ? canfd_ext_flags_id : can_ext_flags_id;

        } else {

            frame_type = LINUX_CAN_STD;

            can_info.id &= (CAN_SFF_MASK | CAN_FLAG_MASK);

            can_flags_id  = (can_packet_type == PACKET_TYPE_CAN_FD) ? canfd_std_flags_id : can_std_flags_id;

        }

        socketcan_set_source_and_destination_columns(pinfo, &can_info);

        proto_tree_add_bitmask_list(can_tree, tvb, 0, 4, can_flags_id, encoding);

        if (can_info.id & CAN_EFF_FLAG) {

            col_add_fstr(pinfo->cinfo, COL_INFO, "Ext. ID: %u (0x%08x)", can_info.id & CAN_EFF_MASK, can_info.id & CAN_EFF_MASK);

            proto_item_append_text(can_tree, ", Ext. ID: %u (0x%08x)", can_info.id & CAN_EFF_MASK, can_info.id & CAN_EFF_MASK);

        } else {

            col_add_fstr(pinfo->cinfo, COL_INFO, "ID: %u (0x%03x)", can_info.id & CAN_SFF_MASK, can_info.id & CAN_SFF_MASK);

            proto_item_append_text(can_tree, ", ID: %u (0x%03x)", can_info.id & CAN_SFF_MASK, can_info.id & CAN_SFF_MASK);

        }

        proto_tree_add_item_ret_uint(can_tree, hf_can_len, tvb, CAN_LEN_OFFSET, 1, ENC_NA, &can_info.len);

        col_append_fstr(pinfo->cinfo, COL_INFO, ", Length: %u", can_info.len);

        proto_item_append_text(can_tree, ", Length: %u", can_info.len);

        if (frame_type == LINUX_CAN_ERR && can_info.len != CAN_ERR_DLC) {

            proto_tree_add_expert(tree, pinfo, &ei_can_err_dlc_mismatch, tvb, CAN_LEN_OFFSET, 1);

        }

        if (can_packet_type == PACKET_TYPE_CAN_FD) {

            proto_tree_add_bitmask_list(can_tree, tvb, CANFD_FLAG_OFFSET, 1, canfd_flag_fields, ENC_NA);

            proto_tree_add_item(can_tree, hf_can_reserved, tvb, CANFD_FLAG_OFFSET+1, 2, ENC_NA);

        } else {

            proto_tree_add_item(can_tree, hf_can_reserved, tvb, CANFD_FLAG_OFFSET, 2, ENC_NA);

            proto_tree_add_item(can_tree, hf_can_len8dlc, tvb, CANFD_FLAG_OFFSET+2, 1, ENC_NA);

        }

        if (frame_type == LINUX_CAN_ERR) {

            int * const *flag;

            const char *sepa = ": ";

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

            for (flag = can_err_flags; *flag; flag++) {

                header_field_info *hfi;

                hfi = proto_registrar_get_nth(**flag);

                if (!hfi)

                    continue;

                if ((can_info.id & hfi->bitmask & ~CAN_FLAG_MASK) == 0)

                    continue;

                col_append_sep_str(pinfo->cinfo, COL_INFO, sepa, hfi->name);

                sepa = ", ";

            }

            if (can_info.id & CAN_ERR_LOSTARB) {

                proto_tree_add_item(can_tree, hf_can_err_lostarb_bit_number, tvb, CAN_DATA_OFFSET + 0, 1, ENC_NA);

            }

            if (can_info.id & CAN_ERR_CTRL) {

                static int * const can_err_ctrl_flags[] = {

                    &hf_can_err_ctrl_rx_overflow,

                    &hf_can_err_ctrl_tx_overflow,

                    &hf_can_err_ctrl_rx_warning,

                    &hf_can_err_ctrl_tx_warning,

                    &hf_can_err_ctrl_rx_passive,

                    &hf_can_err_ctrl_tx_passive,

                    &hf_can_err_ctrl_active,

                    NULL,

                };

                proto_tree_add_bitmask_list(can_tree, tvb, CAN_DATA_OFFSET+1, 1, can_err_ctrl_flags, ENC_NA);

           }

           if (can_info.id & CAN_ERR_PROT) {

                static int * const can_err_prot_error_type_flags[] = {

                    &hf_can_err_prot_error_type_bit,

                    &hf_can_err_prot_error_type_form,

                    &hf_can_err_prot_error_type_stuff,

                    &hf_can_err_prot_error_type_bit0,

                    &hf_can_err_prot_error_type_bit1,

                    &hf_can_err_prot_error_type_overload,

                    &hf_can_err_prot_error_type_active,

                    &hf_can_err_prot_error_type_tx,

                    NULL

                };

                proto_tree_add_bitmask_list(can_tree, tvb, CAN_DATA_OFFSET+2, 1, can_err_prot_error_type_flags, ENC_NA);

                proto_tree_add_item(can_tree, hf_can_err_prot_error_location, tvb, CAN_DATA_OFFSET+3, 1, ENC_NA);

            }

            if (can_info.id & CAN_ERR_TRX) {

                proto_tree_add_item(can_tree, hf_can_err_trx_canh, tvb, CAN_DATA_OFFSET+4, 1, ENC_NA);

                proto_tree_add_item(can_tree, hf_can_err_trx_canl, tvb, CAN_DATA_OFFSET+4, 1, ENC_NA);

            }

            proto_tree_add_item(can_tree, hf_can_err_ctrl_specific, tvb, CAN_DATA_OFFSET+5, 3, ENC_NA);

        } else {

            tvbuff_t   *next_tvb;

            if (can_info.id & CAN_RTR_FLAG) {

                col_append_str(pinfo->cinfo, COL_INFO, " (Remote Transmission Request)");

            }

            next_tvb = tvb_new_subset_length(tvb, CAN_DATA_OFFSET, can_info.len);

            if (!socketcan_call_subdissectors(next_tvb, pinfo, tree, &can_info, heuristic_first)) {

                call_data_dissector(next_tvb, pinfo, tree);

           }

        }

        if (tvb_captured_length_remaining(tvb, CAN_DATA_OFFSET+can_info.len) > 0) {

            proto_tree_add_item(can_tree, hf_can_padding, tvb, CAN_DATA_OFFSET+can_info.len, -1, ENC_NA);

        }

    }

    return tvb_captured_length(tvb);

}

static int

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

    return dissect_socketcan_common(tvb, pinfo, tree,

                                    byte_swap ? ENC_LITTLE_ENDIAN : ENC_BIG_ENDIAN,

                                    ENC_LITTLE_ENDIAN,

                                    PACKET_TYPE_UNKNOWN);

}

static int

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

    return dissect_socketcan_common(tvb, pinfo, tree,

                                    byte_swap ? ENC_ANTI_HOST_ENDIAN : ENC_HOST_ENDIAN,

                                    ENC_HOST_ENDIAN, /* Not used, as this is CAN classic, not CAN XL */

                                    PACKET_TYPE_CAN);

}

static int

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

    return dissect_socketcan_common(tvb, pinfo, tree,

                                    byte_swap ? ENC_ANTI_HOST_ENDIAN : ENC_HOST_ENDIAN,

                                    ENC_HOST_ENDIAN, /* Not used, as this is CAN FD, not CAN XL */

                                    PACKET_TYPE_CAN_FD);

}

static int

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

    return dissect_socketcan_common(tvb, pinfo, tree,

                                    byte_swap ? ENC_ANTI_HOST_ENDIAN : ENC_HOST_ENDIAN,

                                    ENC_HOST_ENDIAN,

                                    PACKET_TYPE_CAN_XL);

}

void

proto_register_socketcan(void) {

    static hf_register_info hf[] = {

        { &hf_can_bus_id, {

            "Bus ID", "can.bus_id", FT_UINT32, BASE_HEX, NULL, 0x0, NULL, HFILL } },

        { &hf_can_infoent_ext, {

            "ID", "can.id", FT_UINT32, BASE_DEC_HEX, NULL, CAN_EFF_MASK, NULL, HFILL } },

        { &hf_can_infoent_std, {

            "ID", "can.id", FT_UINT32, BASE_DEC_HEX, NULL, CAN_SFF_MASK, NULL, HFILL } },

        { &hf_can_extflag, {

            "Extended Flag", "can.flags.xtd", FT_BOOLEAN, 32, NULL, CAN_EFF_FLAG, NULL, HFILL } },

        { &hf_can_rtrflag, {

            "Remote Transmission Request Flag", "can.flags.rtr", FT_BOOLEAN, 32, NULL, CAN_RTR_FLAG, NULL, HFILL } },

        { &hf_can_errflag, {

            "Error Message Flag", "can.flags.err", FT_BOOLEAN, 32, NULL, CAN_ERR_FLAG, NULL, HFILL } },

        { &hf_can_len, {

            "Frame-Length", "can.len", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL } },

        { &hf_can_len8dlc, {

            "Len 8 DLC", "can.len8dlc", FT_UINT8, BASE_DEC, NULL, 0x0, NULL, HFILL } },

        { &hf_can_reserved, {

            "Reserved", "can.reserved", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL } },

        { &hf_can_padding, {

            "Padding", "can.padding", FT_BYTES, BASE_NONE, NULL, 0x0, NULL, HFILL } },

        { &hf_canfd_brsflag, {

            "Bit Rate Setting", "canfd.flags.brs", FT_BOOLEAN, 8, NULL, CANFD_BRS, NULL, HFILL } },

        { &hf_canfd_esiflag, {

            "Error State Indicator", "canfd.flags.esi", FT_BOOLEAN, 8, NULL, CANFD_ESI, NULL, HFILL } },

        { &hf_canfd_fdflag, {

            "FD Frame", "canfd.flags.fdf", FT_BOOLEAN, 8, NULL, CANFD_FDF, NULL, HFILL } },

        { &hf_can_err_tx_timeout, {

            "Transmit timeout", "can.err.tx_timeout", FT_BOOLEAN, 32, NULL, CAN_ERR_TX_TIMEOUT, NULL, HFILL } },

        { &hf_can_err_lostarb, {

            "Lost arbitration", "can.err.lostarb", FT_BOOLEAN, 32, NULL, CAN_ERR_LOSTARB, NULL, HFILL } },

        { &hf_can_err_ctrl, {

            "Controller problems", "can.err.ctrl", FT_BOOLEAN, 32, NULL, CAN_ERR_CTRL, NULL, HFILL } },

        { &hf_can_err_prot, {

            "Protocol violation", "can.err.prot", FT_BOOLEAN, 32, NULL, CAN_ERR_PROT, NULL, HFILL } },

        { &hf_can_err_trx, {

            "Transceiver status", "can.err.trx", FT_BOOLEAN, 32, NULL, CAN_ERR_TRX, NULL, HFILL } },

        { &hf_can_err_ack, {

            "No acknowledgment", "can.err.ack", FT_BOOLEAN, 32, NULL, CAN_ERR_ACK, NULL, HFILL } },

        { &hf_can_err_busoff, {

            "Bus off", "can.err.busoff", FT_BOOLEAN, 32, NULL, CAN_ERR_BUSOFF, NULL, HFILL } },

        { &hf_can_err_buserror, {

            "Bus error", "can.err.buserror", FT_BOOLEAN, 32, NULL, CAN_ERR_BUSERROR, NULL, HFILL } },

        { &hf_can_err_restarted, {

            "Controller restarted", "can.err.restarted", FT_BOOLEAN, 32, NULL, CAN_ERR_RESTARTED, NULL, HFILL } },

        { &hf_can_err_reserved, {

            "Reserved", "can.err.reserved", FT_UINT32, BASE_HEX, NULL, CAN_ERR_RESERVED, NULL, HFILL } },

        { &hf_can_err_lostarb_bit_number, {

            "Lost arbitration in bit number", "can.err.lostarb.bitnum", FT_UINT8, BASE_DEC, NULL, 0, NULL, HFILL } },

        { &hf_can_err_ctrl_rx_overflow, {

            "RX buffer overflow", "can.err.ctrl.rx_overflow", FT_BOOLEAN, 8, NULL, 0x01, NULL, HFILL } },

        { &hf_can_err_ctrl_tx_overflow, {

            "TX buffer overflow", "can.err.ctrl.tx_overflow", FT_BOOLEAN, 8, NULL, 0x02, NULL, HFILL } },

        { &hf_can_err_ctrl_rx_warning, {

            "Reached warning level for RX errors", "can.err.ctrl.rx_warning", FT_BOOLEAN, 8, NULL, 0x04, NULL, HFILL } },

        { &hf_can_err_ctrl_tx_warning, {

            "Reached warning level for TX errors", "can.err.ctrl.tx_warning", FT_BOOLEAN, 8, NULL, 0x08, NULL, HFILL } },

        { &hf_can_err_ctrl_rx_passive, {

            "Reached error passive status RX", "can.err.ctrl.rx_passive", FT_BOOLEAN, 8, NULL, 0x10, NULL, HFILL } },

        { &hf_can_err_ctrl_tx_passive, {

            "Reached error passive status TX", "can.err.ctrl.tx_passive", FT_BOOLEAN, 8, NULL, 0x20, NULL, HFILL } },

        { &hf_can_err_ctrl_active, {

            "Recovered to error active state", "can.err.ctrl.active", FT_BOOLEAN, 8, NULL, 0x40, NULL, HFILL } },

        { &hf_can_err_prot_error_type_bit, {

            "Single bit error", "can.err.prot.type.bit", FT_BOOLEAN, 8, NULL, CAN_ERR_PROT_BIT, NULL, HFILL } },

        { &hf_can_err_prot_error_type_form, {

            "Frame format error", "can.err.prot.type.form", FT_BOOLEAN, 8, NULL, CAN_ERR_PROT_FORM, NULL, HFILL } },

        { &hf_can_err_prot_error_type_stuff, {

            "Bit stuffing error", "can.err.prot.type.stuff", FT_BOOLEAN, 8, NULL, CAN_ERR_PROT_STUFF, NULL, HFILL } },

        { &hf_can_err_prot_error_type_bit0, {

            "Unable to send dominant bit", "can.err.prot.type.bit0", FT_BOOLEAN, 8, NULL, CAN_ERR_PROT_BIT0, NULL, HFILL } },

        { &hf_can_err_prot_error_type_bit1, {

            "Unable to send recessive bit", "can.err.prot.type.bit1", FT_BOOLEAN, 8, NULL, CAN_ERR_PROT_BIT1, NULL, HFILL } },

        { &hf_can_err_prot_error_type_overload, {

            "Bus overload", "can.err.prot.type.overload", FT_BOOLEAN, 8, NULL, CAN_ERR_PROT_OVERLOAD, NULL, HFILL } },

        { &hf_can_err_prot_error_type_active, {

            "Active error announcement", "can.err.prot.type.active", FT_BOOLEAN, 8, NULL, CAN_ERR_PROT_ACTIVE, NULL, HFILL } },

        { &hf_can_err_prot_error_type_tx, {

            "Error occurred on transmission", "can.err.prot.type.tx", FT_BOOLEAN, 8, NULL, CAN_ERR_PROT_TX, NULL, HFILL } },

        { &hf_can_err_prot_error_location, {

            "Protocol error location", "can.err.prot.location", FT_UINT8, BASE_DEC, VALS(can_err_prot_error_location_vals), 0, NULL, HFILL } },

        { &hf_can_err_trx_canh, {

            "Transceiver CANH status", "can.err.trx.canh", FT_UINT8, BASE_DEC, VALS(can_err_trx_canh_vals), 0x0F, NULL, HFILL } },

        { &hf_can_err_trx_canl, {

            "Transceiver CANL status", "can.err.trx.canl", FT_UINT8, BASE_DEC, VALS(can_err_trx_canl_vals), 0xF0, NULL, HFILL } },

        { &hf_can_err_ctrl_specific, {

            "Controller specific data", "can.err.ctrl_specific", FT_BYTES, SEP_SPACE, NULL, 0, NULL, HFILL } },

        { &hf_canxl_priority, {

            "Priority", "canxl.priority", FT_UINT32, BASE_DEC, NULL, 0x0000FFFF, NULL, HFILL } },

        { &hf_canxl_vcid, {

            "VCID", "canxl.vcid", FT_UINT32, BASE_DEC, NULL, 0x00FF0000, NULL, HFILL } },

        { &hf_canxl_secflag, {

            "Simple Extended Content", "canxl.flags.sec", FT_BOOLEAN, 8, NULL, CANXL_SEC, NULL, HFILL } },

        { &hf_canxl_rrsflag, {

            "Remote Request Substitution", "canxl.flags.rrs", FT_BOOLEAN, 8, NULL, CANXL_RRS, NULL, HFILL } },

        { &hf_canxl_xlflag, {

            "XL Frame", "canxl.flags.xl", FT_BOOLEAN, 8, NULL, CANXL_XLF, NULL, HFILL } },

        { &hf_canxl_sdu_type, {

            "SDU type", "canxl.sdu_type", FT_UINT8, BASE_HEX, VALS(canxl_sdu_type_vals), 0, NULL, HFILL } },

        { &hf_canxl_len, {

            "Frame-Length", "canxl.len", FT_UINT16, BASE_DEC, NULL, 0x0, NULL, HFILL } },

        { &hf_canxl_acceptance_field, {

            "Acceptance field", "canxl.acceptance_field", FT_UINT32, BASE_DEC_HEX, NULL, 0, NULL, HFILL } },

    };

    uat_t *can_interface_uat = NULL;

    uat_t *sender_receiver_uat = NULL;

    /* Setup protocol subtree array */

    static int *ett[] = {

        &ett_can,

        &ett_can_fd,

        &ett_can_xl

    };

    static ei_register_info ei[] = {

        { &ei_can_err_dlc_mismatch, {

            "can.err.dlc_mismatch", PI_MALFORMED, PI_ERROR, "ERROR: DLC mismatch", EXPFILL } }

    };

    module_t *can_module;

    proto_can = proto_register_protocol("Controller Area Network", "CAN", "can");

    /*

     * "can-hostendian" is a legacy name (there never was, in any libpcap

     * release, a SocketCAN LINKTYPE_ value for a host-endian CAN ID

     * and flags field); we need to keep it around in case some candump

     * or Busmaster capture that was saved as a pcap or pcapng file,

     * as those use a linktype of LINKTYPE_WIRESHARK_UPPER_PDU with

     * "can-hostendian" as the dissector name.

     *

     * "can-bigendian" is also a legacy name (fpr CAN XL frames, the

     * fields in the header are in *little-endian* order); we keep it

     * around for the same reason.  It's used for the dissector for

     * LINKTYPE_CAN_SOCKETCAN.

     */

    socketcan_classic_handle = register_dissector("can-hostendian", dissect_socketcan_classic, proto_can);

    socketcan_bigendian_handle = register_dissector("can-bigendian", dissect_socketcan_bigendian, proto_can);

    proto_canfd = proto_register_protocol("Controller Area Network FD", "CANFD", "canfd");

    socketcan_fd_handle = register_dissector("canfd", dissect_socketcan_fd, proto_canfd);

    proto_canxl = proto_register_protocol("Controller Area Network XL", "CANXL", "canxl");

    socketcan_xl_handle = register_dissector("canxl", dissect_socketcan_xl, proto_canxl);