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

/* packet-nordic_ble.c
 * Routines for nRF Sniffer for Bluetooth LE dissection
 *
 * Copyright (c) 2016-2018 Nordic Semiconductor.
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

/* nRF Sniffer for Bluetooth LE packet format: BoardID + Header + Payload
 *
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *  |                           BoardID  (1 byte)                           |
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *
 * Header version 0 (legacy):
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *  |                          Packet ID  (1 byte)                          |
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *  |                         Packet counter (LSB)                          |
 *  |                               (2 bytes)                               |
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *  |                                Unused                                 |
 *  |                               (2 bytes)                               |
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *  |                      Length of payload  (1 byte)                      |
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *
 * Header version 1:
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *  |                      Length of header  (1 byte)                       |
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *  |                      Length of payload  (1 byte)                      |
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *  |                      Protocol version  (1 byte)                       |
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *  |                         Packet counter (LSB)                          |
 *  |                               (2 bytes)                               |
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *  |                          Packet ID  (1 byte)                          |
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *
 * Header version > 1:
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *  |                   Length of payload (little endian)                   |
 *  |                               (2 bytes)                               |
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *  |                      Protocol version  (1 byte)                       |
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *  |                    Packet counter (little endian)                     |
 *  |                               (2 bytes)                               |
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *  |                          Packet ID  (1 byte)                          |
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *
 *  Packet ID:
 *   0x00 = REQ_FOLLOW
 *          Host tells the Sniffer to scan for Advertising from a specific
 *          address and follow all communication it has with other devices.
 *
 *   0x01 = EVENT_FOLLOW
 *          Sniffer tells the Host that it has entered the FOLLOW state.
 *
 *   0x02 = EVENT_PACKET_ADVERTISING
 *          Sniffer tells the Host that it has received an advertising physical
 *          channel PDU.
 *
 *   0x05 = EVENT_CONNECT
 *          Sniffer tells the Host that someone has connected to the unit we
 *          are following.
 *
 *   0x06 = EVENT_PACKET_DATA
 *   Protocol version < 3:
 *          Sniffer tells the host that it has received a packet on any physical
 *          channel.
 *          Access address == 0x8e89bed6 Advertising physical channel PDU
 *          Access address != 0x8e89bed6 Data physical channel PDU
 *   Protocol version 3:
 *          Sniffer tells the Host that it has received a data physical
 *          channel PDU.
 *
 *   0x07 = REQ_SCAN_CONT
 *          Host tells the Sniffer to scan continuously for any advertising
 *          physical channel PDUs and send all packets received.
 *
 *   0x09 = EVENT_DISCONNECT
 *          Sniffer tells the Host that the connected address we were following
 *          has received a disconnect packet.
 *
 *   0x0C = SET_TEMPORARY_KEY
 *          Specify a temporary key (TK) to use on encryption.
 *          Only used for Legacy OOB and Legacy passkey pairing.
 *
 *   0x0D = PING_REQ
 *
 *   0x0E = PING_RESP
 *
 *   0x13 = SWITCH_BAUD_RATE_REQ
 *
 *   0x14 = SWITCH_BAUD_RATE_RESP
 *
 *   0x17 = SET_ADV_CHANNEL_HOP_SEQ
 *          Host tells the Sniffer which order to cycle through the channels
 *          when following an advertiser.
 *
 *   0xFE = GO_IDLE
 *          Host tell the Sniffer to stop sending UART traffic and listen for
 *          new commands.
 *
 * Payloads:
 *
 *  Protocol version < 3:
 *  EVENT_PACKET             (ID 0x06)
 *
 *  Protocol version 3:
 *  EVENT_PACKET_ADVERTISING (ID 0x02)
 *  EVENT_PACKET_DATA        (ID 0x06)
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *  |                   Length of payload data  (1 byte)                    |
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *  |                            Flags  (1 byte)                            |
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *  |                           Channel  (1 byte)                           |
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *  |                      RSSISample (dBm)  (1 byte)                       |
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *  |                             Event counter                             |
 *  |                               (2 bytes)                               |
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *  |  Protocol version < 3:    Delta time (us end to start)                |
 *  |                                    (4 bytes)                          |
 *  |  Protocol version 3:      Firmware  Timestamp (us)                    |
 *  |                                    (4 bytes)                          |
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *  |                                                                       |
 *  |      Bluetooth Low Energy Link Layer Packet (excluding preamble)      |
 *  |                                  ...                                  |
 *  |                                                                       |
 *  +--------+--------+--------+--------+--------+--------+--------+--------+
 *
 *  Flags EVENT_PACKET_ADVERTISING (0x02)
 *   0000000x = CRC       (0 = Incorrect, 1 = OK)
 *   000000x0 = RFU
 *   00000x00 = RFU
 *   00000xx0 = AUX_TYPE  (channel < 37: 0 = AUX_ADV_IND, 1 = AUX_CHAIN_IND,
 *                                       2 = AUX_SYNC_IND, 3 = AUX_SCAN_RSP)
 *   0000x000 = RFU
 *   0xxx0000 = PHY       (0 = 1M, 1 = 2M, 2 = Coded, rest unused)
 *   x0000000 = RFU
 *
 *  Flags EVENT_PACKET_DATA (0x06)
 *   0000000x = CRC       (0 = Incorrect, 1 = OK)
 *   000000x0 = Direction (0 = Slave -> Master, 1 = Master -> Slave)
 *   00000x00 = Encrypted (0 = No, 1 = Yes)
 *   0000x000 = MIC       (0 = Incorrect, 1 = OK)
 *   0xxx0000 = PHY       (0 = 1M, 1 = 2M, 2 = Coded, rest unused)
 *   x0000000 = RFU
 *
 *  Channel:
 *   The channel index being used.
 *
 * RSSIsample:
 *   RSSI sample raw value. The value of this register is read as a
 *   positive value while the actual received signal strength is a
 *   negative value. Actual received signal strength is therefore
 *   as follows: rssi = -RSSISAMPLE dBm
 *
 *  Delta time:
 *   This is the time in microseconds from the end of the previous received
 *   packet to the beginning of this packet.
 *
 *  Firmware timestamp:
 *    Timestamp of the start of the received packet captured by the firmware
 *    timer with microsecond resolution.
 */

#include "config.h"

#include <epan/packet.h>
#include <epan/expert.h>
#include <epan/proto_data.h>

#include <wsutil/utf8_entities.h>
#include <wiretap/wtap.h>

#include "packet-btle.h"

/* Size of various UART Packet header fields */
#define UART_HEADER_LEN      6
#define EVENT_PACKET_LEN    10

#define US_PER_BYTE_1M_PHY   8
#define US_PER_BYTE_2M_PHY   4

#define US_PER_BYTE_CODED_PHY_S8 64
#define US_PER_BYTE_CODED_PHY_S2 16

#define PREAMBLE_LEN_1M_PHY  1
#define PREAMBLE_LEN_2M_PHY  2

/* Preamble + Access Address + CI + TERM1 */
#define FEC1_BLOCK_S8_US (80 + 256 + 16 + 24)
#define TERM2_S8_US      24
#define TERM2_S2_US       6

void proto_reg_handoff_nordic_ble(void);
void proto_register_nordic_ble(void);

static dissector_handle_t nordic_ble_handle;

/* Initialize the protocol and registered fields */
static int proto_nordic_ble = -1;

/* Initialize the subtree pointers */
static gint ett_nordic_ble = -1;
static gint ett_packet_header = -1;
static gint ett_flags = -1;

static int hf_nordic_ble_board_id = -1;
static int hf_nordic_ble_legacy_marker = -1;
static int hf_nordic_ble_header = -1;
static int hf_nordic_ble_header_length = -1;
static int hf_nordic_ble_payload_length = -1;
static int hf_nordic_ble_protover = -1;
static int hf_nordic_ble_packet_counter = -1;
static int hf_nordic_ble_packet_id = -1;
static int hf_nordic_ble_packet_length = -1;
static int hf_nordic_ble_flags = -1;
static int hf_nordic_ble_crcok = -1;
static int hf_nordic_ble_encrypted = -1;
static int hf_nordic_ble_micok = -1;
static int hf_nordic_ble_mic_not_relevant = -1;
static int hf_nordic_ble_aux_type = -1;
static int hf_nordic_ble_flag_reserved1 = -1;
static int hf_nordic_ble_flag_reserved2 = -1;
static int hf_nordic_ble_address_resolved = -1;
static int hf_nordic_ble_flag_reserved7 = -1;
static int hf_nordic_ble_le_phy = -1;
static int hf_nordic_ble_direction = -1;
static int hf_nordic_ble_channel = -1;
static int hf_nordic_ble_rssi = -1;
static int hf_nordic_ble_event_counter = -1;
static int hf_nordic_ble_time = -1;
static int hf_nordic_ble_delta_time = -1;
static int hf_nordic_ble_delta_time_ss = -1;
static int hf_nordic_ble_packet_time = -1;

static expert_field ei_nordic_ble_bad_crc = EI_INIT;
static expert_field ei_nordic_ble_bad_mic = EI_INIT;
static expert_field ei_nordic_ble_bad_length = EI_INIT;
static expert_field ei_nordic_ble_unknown_version = EI_INIT;

static const true_false_string direction_tfs =
{
    "Master -> Slave",
    "Slave -> Master"
};

static const value_string le_phys[] =
{
    { 0, "LE 1M"    },
    { 1, "LE 2M"    },
    { 2, "LE Coded" },
    { 3, "Reserved" },
    { 4, "Reserved" },
    { 5, "Reserved" },
    { 6, "Reserved" },
    { 7, "Reserved" },
    { 0, NULL }
};

#define CI_S8 0
#define CI_S2 1

static const value_string le_aux_ext_adv[] = {
    { 0, "AUX_ADV_IND" },
    { 1, "AUX_CHAIN_IND" },
    { 2, "AUX_SYNC_IND" },
    { 3, "AUX_SCAN_RSP" },
    { 0, NULL }
};

typedef struct {
    guint8 protover;
    guint8 phy;
    gboolean bad_length;
    guint16 payload_length;
    guint16 event_packet_length;
} nordic_ble_context_t;

/* next dissector */
static dissector_handle_t btle_dissector_handle = NULL;
static dissector_handle_t debug_handle = NULL;

static gint
dissect_lengths(tvbuff_t *tvb, gint offset, packet_info *pinfo, proto_tree *tree, nordic_ble_context_t *nordic_ble_context)
{
    guint32 hlen, plen;
    proto_item* item;

    switch (nordic_ble_context->protover) {
    case 0:  /* Legacy version */
        hlen = 2 + UART_HEADER_LEN; /* 2 bytes legacy marker + UART header */
        item = proto_tree_add_item_ret_uint(tree, hf_nordic_ble_payload_length, tvb, offset, 1, ENC_NA, &plen);
        offset += 1;
        break;

    case 1:
        proto_tree_add_item_ret_uint(tree, hf_nordic_ble_header_length, tvb, offset, 1, ENC_NA, &hlen);
        hlen += 1; /* Add one byte for board id */
        offset += 1;

        item = proto_tree_add_item_ret_uint(tree, hf_nordic_ble_payload_length, tvb, offset, 1, ENC_NA, &plen);
        offset += 1;
        break;

    default: /* Starting from version 2 */
        hlen = 1 + UART_HEADER_LEN; /* Board ID + UART header */
        item = proto_tree_add_item_ret_uint(tree, hf_nordic_ble_payload_length, tvb, offset, 2, ENC_LITTLE_ENDIAN, &plen);
        offset += 2;
        break;
    }

    if ((hlen + plen) != tvb_captured_length(tvb)) {
        expert_add_info(pinfo, item, &ei_nordic_ble_bad_length);
        nordic_ble_context->bad_length = TRUE;
    }

    nordic_ble_context->payload_length = plen;

    return offset;
}

static gint
dissect_flags(tvbuff_t *tvb, gint offset, packet_info *pinfo, proto_tree *tree, nordic_ble_context_t *nordic_ble_context, btle_context_t *context)
{
    guint8 flags, channel;
    gboolean dir;
    proto_item *flags_item, *item;
    proto_tree *flags_tree;

    flags = tvb_get_guint8(tvb, offset);
    channel = tvb_get_guint8(tvb, offset + 1);

    if (nordic_ble_context->protover < 3) {
        guint32 access_address;

        access_address = tvb_get_letohl(tvb, offset + nordic_ble_context->event_packet_length - 1);
        context->pdu_type = access_address == ACCESS_ADDRESS_ADVERTISING ? BTLE_PDU_TYPE_ADVERTISING : BTLE_PDU_TYPE_DATA;
    }

    context->crc_checked_at_capture = 1;
    context->crc_valid_at_capture = !!(flags & 1);

    if (context->pdu_type == BTLE_PDU_TYPE_DATA) {
        dir = !!(flags & 2);
        context->mic_checked_at_capture = !!(flags & 4);
        if (context->mic_checked_at_capture) {
            context->mic_valid_at_capture = !!(flags & 8);
        }
    }

    nordic_ble_context->phy = (flags >> 4) & 7;
    context->phy = nordic_ble_context->phy;

    if (context->pdu_type == BTLE_PDU_TYPE_DATA) {
        if (dir) {
            set_address(&pinfo->src, AT_STRINGZ, 7, "Master");
            set_address(&pinfo->dst, AT_STRINGZ, 6, "Slave");
            context->direction = BTLE_DIR_MASTER_SLAVE;
            pinfo->p2p_dir = P2P_DIR_SENT;
        } else {
            set_address(&pinfo->src, AT_STRINGZ, 6, "Slave");
            set_address(&pinfo->dst, AT_STRINGZ, 7, "Master");
            context->direction = BTLE_DIR_SLAVE_MASTER;
            pinfo->p2p_dir = P2P_DIR_RECV;
        }
    }

    flags_item = proto_tree_add_item(tree, hf_nordic_ble_flags, tvb, offset, 1, ENC_NA);
    flags_tree = proto_item_add_subtree(flags_item, ett_flags);
    item = proto_tree_add_item(flags_tree, hf_nordic_ble_crcok, tvb, offset, 1, ENC_NA);
    if (!context->crc_valid_at_capture) {
        /* CRC is bad */
        expert_add_info(pinfo, item, &ei_nordic_ble_bad_crc);
    }

    if (context->pdu_type == BTLE_PDU_TYPE_DATA) {
        proto_tree_add_item(flags_tree, hf_nordic_ble_direction, tvb, offset, 1, ENC_NA);
        proto_tree_add_item(flags_tree, hf_nordic_ble_encrypted, tvb, offset, 1, ENC_NA);
        if (context->mic_checked_at_capture) {
            item = proto_tree_add_item(flags_tree, hf_nordic_ble_micok, tvb, offset, 1, ENC_NA);
            if (!context->mic_valid_at_capture) {
                /* MIC is bad */
                expert_add_info(pinfo, item, &ei_nordic_ble_bad_mic);
            }
        } else {
            proto_tree_add_item(flags_tree, hf_nordic_ble_mic_not_relevant, tvb, offset, 1, ENC_NA);
        }
    } else {
        if (channel < 37) {
            guint32 aux_pdu_type;

            proto_tree_add_item_ret_uint(flags_tree, hf_nordic_ble_aux_type, tvb, offset, 1, ENC_NA, &aux_pdu_type);
            context->aux_pdu_type = aux_pdu_type;
            context->aux_pdu_type_valid = TRUE;
        } else {
            proto_tree_add_item(flags_tree, hf_nordic_ble_flag_reserved1, tvb, offset, 1, ENC_NA);
            proto_tree_add_item(flags_tree, hf_nordic_ble_flag_reserved2, tvb, offset, 1, ENC_NA);
        }
        proto_tree_add_item(flags_tree, hf_nordic_ble_address_resolved, tvb, offset, 1, ENC_NA);
    }

    proto_tree_add_item(flags_tree, hf_nordic_ble_le_phy, tvb, offset, 1, ENC_NA);
    proto_tree_add_item(flags_tree, hf_nordic_ble_flag_reserved7, tvb, offset, 1, ENC_NA);

    offset++;

    return offset;
}

static guint16 packet_time_get(nordic_ble_context_t *nordic_ble_context, guint8 ci)
{
    /* Calculate packet time according to this packets PHY */
    guint16 ble_payload_length = nordic_ble_context->payload_length - nordic_ble_context->event_packet_length;

    switch (nordic_ble_context->phy) {
        case LE_1M_PHY:
            return  US_PER_BYTE_1M_PHY * (PREAMBLE_LEN_1M_PHY + ble_payload_length);
        case LE_2M_PHY:
            return US_PER_BYTE_2M_PHY * (PREAMBLE_LEN_2M_PHY + ble_payload_length);
        case LE_CODED_PHY:
        {
            /* Subtract Access address and CI */
            guint16 fec2_block_len = ble_payload_length - 4 - 1;

            switch (ci) {
                case CI_S8:
                    return FEC1_BLOCK_S8_US + fec2_block_len * US_PER_BYTE_CODED_PHY_S8 + TERM2_S8_US;
                case CI_S2:
                    return FEC1_BLOCK_S8_US + fec2_block_len * US_PER_BYTE_CODED_PHY_S2 + TERM2_S2_US;
            }
        }
        /* Fallthrough */
        default:
            return 0; /* Unknown */
    }
}

typedef struct
{
    guint32 packet_start_time;
    guint32 packet_end_time;
} packet_times_t;

typedef struct {
    gboolean first_frame_seen;
    /* Time information about previous packet times to calculate delta times */
    guint32 packet_time;
    guint32 packet_start_time;
    guint32 packet_end_time;
} packet_time_context_t;

static wmem_tree_t *packet_time_context_tree;

static packet_time_context_t *packet_times_get(packet_info *pinfo)
{
    guint32 interface_id = (pinfo->rec->presence_flags & WTAP_HAS_INTERFACE_ID) ? pinfo->rec->rec_header.packet_header.interface_id: HCI_INTERFACE_DEFAULT;
    wmem_tree_t *wmem_tree;
    wmem_tree_key_t keys[2];

    keys[0].length = 1;
    keys[0].key = &interface_id;
    keys[1].length = 0;
    keys[1].key = NULL;

    wmem_tree = (wmem_tree_t *) wmem_tree_lookup32_array(packet_time_context_tree, keys);
    if (wmem_tree) {
        return (packet_time_context_t *) wmem_tree_lookup32_le(wmem_tree, 0);
    }

    return NULL;
}

static packet_time_context_t *packet_times_insert(packet_info *pinfo)
{
    guint32 interface_id = (pinfo->rec->presence_flags & WTAP_HAS_INTERFACE_ID) ? pinfo->rec->rec_header.packet_header.interface_id: HCI_INTERFACE_DEFAULT;
    guint32 key = 0;
    wmem_tree_key_t keys[3];
    packet_time_context_t *packet_times;

    keys[0].length = 1;
    keys[0].key = &interface_id;
    keys[1].length = 1;
    keys[1].key = &key;
    keys[2].length = 0;
    keys[2].key = NULL;
    packet_times = wmem_new0(wmem_file_scope(), packet_time_context_t);
    wmem_tree_insert32_array(packet_time_context_tree, keys, packet_times);

    return packet_times;
}

static gint
dissect_ble_delta_time(tvbuff_t *tvb, gint offset, packet_info *pinfo, proto_tree *tree, nordic_ble_context_t *nordic_ble_context)
{
    guint32 delta_time, delta_time_ss, prev_packet_time, packet_time;
    proto_item *pi;
    packet_time_context_t *packet_times_context;

    packet_times_context = packet_times_get(pinfo);
    if (!packet_times_context) {
        packet_times_context = packet_times_insert(pinfo);
    }

    /* end-to-start */
    proto_tree_add_item_ret_uint(tree, hf_nordic_ble_delta_time, tvb, offset, 4, ENC_LITTLE_ENDIAN, &delta_time);

    if (!pinfo->fd->visited) {
        /* First time visiting this packet, store previous BLE packet time */
        p_add_proto_data(wmem_file_scope(), pinfo, proto_nordic_ble, 0, GUINT_TO_POINTER(packet_times_context->packet_time));
        prev_packet_time = packet_times_context->packet_time;
    } else {
        prev_packet_time = GPOINTER_TO_UINT(p_get_proto_data(wmem_file_scope(), pinfo, proto_nordic_ble, 0));
    }

    if (!packet_times_context->first_frame_seen) {
        delta_time_ss = prev_packet_time + delta_time;
        pi = proto_tree_add_uint(tree, hf_nordic_ble_delta_time_ss, tvb, offset, 4, delta_time_ss);
        proto_item_set_generated(pi);
    }

    packet_time = packet_time_get(nordic_ble_context, 0 /* This version never supported Coded PHY */);
    pi = proto_tree_add_uint(tree, hf_nordic_ble_packet_time, tvb, offset, 4, packet_time);
    proto_item_set_generated(pi);

    offset += 4;

    if (!pinfo->fd->visited) {
        packet_times_context->packet_time = packet_time;
        packet_times_context->first_frame_seen = TRUE;
    }

    return offset;
}

static gint
dissect_ble_timestamp(tvbuff_t *tvb, gint offset, packet_info *pinfo, proto_tree *tree, nordic_ble_context_t *nordic_ble_context)
{
    guint32 delta_time, delta_time_ss, packet_time;
    guint32 timestamp, last_packet_end_time, last_packet_start_time;
    proto_item *item;
    packet_time_context_t *packet_times_context;

    packet_times_context = packet_times_get(pinfo);
    if (!packet_times_context) {
        packet_times_context = packet_times_insert(pinfo);
    }

    proto_tree_add_item_ret_uint(tree, hf_nordic_ble_time, tvb, offset, 4, ENC_LITTLE_ENDIAN, &timestamp);

    if (!pinfo->fd->visited) {
        packet_times_t *saved_packet_times = wmem_new0(wmem_file_scope(), packet_times_t);

        saved_packet_times->packet_end_time = packet_times_context->packet_end_time;
        saved_packet_times->packet_start_time = packet_times_context->packet_start_time;
        p_add_proto_data(wmem_file_scope(), pinfo, proto_nordic_ble, 0, saved_packet_times);

        /* First time visiting this packet, store previous BLE packet time */
        last_packet_end_time = packet_times_context->packet_end_time;
        last_packet_start_time = packet_times_context->packet_start_time;
    } else {
        packet_times_t* saved_packet_times = (packet_times_t *)p_get_proto_data(wmem_file_scope(), pinfo, proto_nordic_ble, 0);

        last_packet_end_time = saved_packet_times->packet_end_time;
        last_packet_start_time = saved_packet_times->packet_start_time;
    }

    guint8 ci = tvb_get_guint8(tvb, offset + 4 + 4);
    packet_time = packet_time_get(nordic_ble_context, ci);
    item = proto_tree_add_uint(tree, hf_nordic_ble_packet_time, tvb, offset, 4, packet_time);
    proto_item_set_generated(item);

    if (pinfo->num > 1) {
        /* Calculated delta times are not valid for the first packet because we don't have the last packet times. */
        delta_time = timestamp - last_packet_end_time;
        item = proto_tree_add_uint(tree, hf_nordic_ble_delta_time, tvb, offset, 4, delta_time);
        proto_item_set_generated(item);

        delta_time_ss = timestamp - last_packet_start_time;
        item = proto_tree_add_uint(tree, hf_nordic_ble_delta_time_ss, tvb, offset, 4, delta_time_ss);
        proto_item_set_generated(item);
    }

    if (!pinfo->fd->visited) {

        packet_times_context->packet_start_time = timestamp;
        packet_times_context->packet_end_time = timestamp + packet_time;
        packet_times_context->first_frame_seen = TRUE;
    }

    offset += 4;

    return offset;
}

static gint
dissect_packet_counter(tvbuff_t *tvb, gint offset, proto_item *item, proto_tree *tree)
{
    proto_item_append_text(item, ", Packet counter: %u", tvb_get_guint16(tvb, offset, ENC_LITTLE_ENDIAN));
    proto_tree_add_item(tree, hf_nordic_ble_packet_counter, tvb, offset, 2, ENC_LITTLE_ENDIAN);
    offset += 2;

    return offset;
}

static gint
dissect_packet_header(tvbuff_t *tvb, gint offset, packet_info *pinfo, proto_tree *tree, nordic_ble_context_t *nordic_ble_context, btle_context_t *context)
{
    proto_item *ti;
    proto_tree *header_tree;
    gint start_offset = offset;

    ti = proto_tree_add_item(tree, hf_nordic_ble_header, tvb, offset, -1, ENC_NA);
    header_tree = proto_item_add_subtree(ti, ett_packet_header);
    proto_item_append_text(ti, " Version: %u", nordic_ble_context->protover);

    if (nordic_ble_context->protover == 0) {
        proto_item *item = proto_tree_add_uint(header_tree, hf_nordic_ble_protover, tvb, 0, 0, 0);
        proto_item_set_generated(item);

        proto_tree_add_item(header_tree, hf_nordic_ble_packet_id, tvb, offset, 1, ENC_NA);
        offset += 1;

        offset = dissect_packet_counter(tvb, offset, ti, header_tree);

        offset += 2; // Two unused bytes
    }

    offset = dissect_lengths(tvb, offset, pinfo, header_tree, nordic_ble_context);

    if (nordic_ble_context->protover != 0) {
        proto_item *item = proto_tree_add_item(header_tree, hf_nordic_ble_protover, tvb, offset, 1, ENC_NA);
        offset += 1;
        if (nordic_ble_context->protover > 3) {
            expert_add_info(pinfo, item, &ei_nordic_ble_unknown_version);
        }

        offset = dissect_packet_counter(tvb, offset, ti, header_tree);

        proto_tree_add_item(header_tree, hf_nordic_ble_packet_id, tvb, offset, 1, ENC_NA);

        if (nordic_ble_context->protover > 2) {
            guint8 id = tvb_get_guint8(tvb, offset);

            context->pdu_type = id == 0x06 ? BTLE_PDU_TYPE_DATA :
                                id == 0x02 ? BTLE_PDU_TYPE_ADVERTISING :
                                             BTLE_PDU_TYPE_UNKNOWN;
        }

        offset += 1;
    }

    proto_item_set_len(ti, offset - start_offset);

    return offset;
}

static gint
dissect_packet(tvbuff_t *tvb, gint offset, packet_info *pinfo, proto_tree *tree, nordic_ble_context_t *nordic_ble_context, btle_context_t *context)
{
    gint32 rssi;
    guint32 channel, event_counter;

    if (nordic_ble_context->protover == 0) {
        // Event packet length is fixed for the legacy version
        nordic_ble_context->event_packet_length = EVENT_PACKET_LEN;
    } else {
        guint32 plen;
        proto_tree_add_item_ret_uint(tree, hf_nordic_ble_packet_length, tvb, offset, 1, ENC_NA, &plen);
        nordic_ble_context->event_packet_length = plen;
        offset += 1;
    }

    offset = dissect_flags(tvb, offset, pinfo, tree, nordic_ble_context, context);

    proto_tree_add_item_ret_uint(tree, hf_nordic_ble_channel, tvb, offset, 1, ENC_NA, &channel);
    offset += 1;

    context->channel = channel;

    rssi = (-1)*((gint32)tvb_get_guint8(tvb, offset));
    proto_tree_add_int(tree, hf_nordic_ble_rssi, tvb, offset, 1, rssi);
    offset += 1;

    proto_tree_add_item_ret_uint(tree, hf_nordic_ble_event_counter, tvb, offset, 2, ENC_LITTLE_ENDIAN, &event_counter);
    offset += 2;

    context->event_counter = event_counter;
    context->event_counter_valid = 1;

    if (nordic_ble_context->protover < 3) {
        offset = dissect_ble_delta_time(tvb, offset, pinfo, tree, nordic_ble_context);
    } else {
        offset = dissect_ble_timestamp(tvb, offset, pinfo, tree, nordic_ble_context);
    }

    return offset;
}

static gint
dissect_header(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, btle_context_t *context, gboolean *bad_length)
{
    proto_item *ti;
    proto_tree *nordic_ble_tree;
    gint offset = 0;
    nordic_ble_context_t nordic_ble_context;

    memset(&nordic_ble_context, 0, sizeof(nordic_ble_context));

    ti = proto_tree_add_item(tree, proto_nordic_ble, tvb, 0, -1, ENC_NA);
    nordic_ble_tree = proto_item_add_subtree(ti, ett_nordic_ble);

    if (tvb_get_guint16(tvb, 0, ENC_BIG_ENDIAN) == 0xBEEF) {
        proto_tree_add_item(nordic_ble_tree, hf_nordic_ble_legacy_marker, tvb, 0, 2, ENC_BIG_ENDIAN);
        offset += 2;

        nordic_ble_context.protover = 0; /* Legacy Version */
    } else {
        proto_tree_add_item(nordic_ble_tree, hf_nordic_ble_board_id, tvb, 0, 1, ENC_NA);
        offset += 1;

        nordic_ble_context.protover = tvb_get_guint8(tvb, offset + 2);
    }

    offset = dissect_packet_header(tvb, offset, pinfo, nordic_ble_tree, &nordic_ble_context, context);
    offset = dissect_packet(tvb, offset, pinfo, nordic_ble_tree, &nordic_ble_context, context);

    proto_item_set_len(ti, offset);
    *bad_length = nordic_ble_context.bad_length;

    return offset;
}

/* Main entry point for sniffer */
static int
dissect_nordic_ble(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
{
    tvbuff_t          *payload_tvb;
    btle_context_t    *context;
    gint               offset;
    gboolean           bad_length = FALSE;

    context = wmem_new0(pinfo->pool, btle_context_t);

    offset = dissect_header(tvb, pinfo, tree, context, &bad_length);
    payload_tvb = tvb_new_subset_length_caplen(tvb, offset, -1, tvb_captured_length(tvb) - offset);

    if (!bad_length) {
        call_dissector_with_data(btle_dissector_handle, payload_tvb, pinfo, tree, context);
    }

    if ((context->mic_checked_at_capture) && (!context->mic_valid_at_capture)) {
        col_set_str(pinfo->cinfo, COL_INFO, "Encrypted packet decrypted incorrectly");
        if (!context->crc_valid_at_capture) {
            /* CRC is bad */
            col_append_str(pinfo->cinfo, COL_INFO, " (bad CRC)");
        } else {
            col_append_str(pinfo->cinfo, COL_INFO, " (bad MIC)");
        }
    }

    if (debug_handle) {
        call_dissector(debug_handle, payload_tvb, pinfo, tree);
    }

    return offset;
}

void
proto_register_nordic_ble(void)
{
    static hf_register_info hf[] = {
        { &hf_nordic_ble_board_id,
            { "Board", "nordic_ble.board_id",
                FT_UINT8, BASE_DEC, NULL, 0x0,
                NULL, HFILL }
        },
        { &hf_nordic_ble_legacy_marker,
            { "Legacy marker", "nordic_ble.legacy_marker",
                FT_UINT16, BASE_HEX, NULL, 0x0,
                NULL, HFILL }
        },
        { &hf_nordic_ble_header,
            { "Header", "nordic_ble.header",
                FT_NONE, BASE_NONE, NULL, 0x0,
                NULL, HFILL }
        },
        { &hf_nordic_ble_header_length,
            { "Length of header", "nordic_ble.hlen",
                FT_UINT8, BASE_DEC, NULL, 0x0,
                NULL, HFILL }
        },
        { &hf_nordic_ble_payload_length,
            { "Length of payload", "nordic_ble.plen",
                FT_UINT16, BASE_DEC, NULL, 0x0,
                "Payload length", HFILL }
        },
        { &hf_nordic_ble_protover,
            { "Protocol version", "nordic_ble.protover",
                FT_UINT8, BASE_DEC, NULL, 0x0,
                NULL, HFILL }
        },
        { &hf_nordic_ble_packet_counter,
            { "Packet counter", "nordic_ble.packet_counter",
                FT_UINT16, BASE_DEC, NULL, 0x0,
                "Global packet counter for packets sent on UART", HFILL }
        },
        { &hf_nordic_ble_packet_id,
            { "Packet ID", "nordic_ble.packet_id",
                FT_UINT8, BASE_DEC, NULL, 0x0,
                NULL, HFILL }
        },
        { &hf_nordic_ble_packet_length,
            { "Length of packet", "nordic_ble.len",
                FT_UINT16, BASE_DEC, NULL, 0x0,
                NULL, HFILL }
        },
        { &hf_nordic_ble_flags,
            { "Flags", "nordic_ble.flags",
                FT_UINT8, BASE_HEX, NULL, 0x0,
                NULL, HFILL }
        },
        { &hf_nordic_ble_crcok,
            { "CRC", "nordic_ble.crcok",
                FT_BOOLEAN, 8, TFS(&tfs_ok_error), 0x01,
                "Cyclic Redundancy Check state", HFILL }
        },
        { &hf_nordic_ble_direction,
            { "Direction", "nordic_ble.direction",
                FT_BOOLEAN, 8, TFS(&direction_tfs), 0x02,
                NULL, HFILL }
        },
        { &hf_nordic_ble_flag_reserved1,
            { "Reserved", "nordic_ble.flag_reserved1",
                FT_UINT8, BASE_DEC, NULL, 0x02,
                NULL, HFILL }
        },
        { &hf_nordic_ble_encrypted,
            { "Encrypted", "nordic_ble.encrypted",
                FT_BOOLEAN, 8, TFS(&tfs_yes_no), 0x04,
                "Was the packet encrypted", HFILL }
        },
        { &hf_nordic_ble_flag_reserved2,
            { "Reserved", "nordic_ble.flag_reserved2",
                FT_UINT8, BASE_DEC, NULL, 0x04,
                NULL, HFILL }
        },
        { &hf_nordic_ble_aux_type,
            { "Aux Type", "nordic_ble.aux_type",
                FT_UINT8, BASE_DEC, VALS(le_aux_ext_adv), 0x06,
                NULL, HFILL }
        },
        { &hf_nordic_ble_micok,
            { "MIC", "nordic_ble.micok",
                FT_BOOLEAN, 8, TFS(&tfs_ok_error), 0x08,
                "Message Integrity Check state", HFILL }
        },
        { &hf_nordic_ble_mic_not_relevant,
            { "MIC (not relevant)", "nordic_ble.mic_not_relevant",
                FT_UINT8, BASE_DEC, NULL, 0x08,
                "Message Integrity Check state is only relevant when encrypted", HFILL }
        },
        { &hf_nordic_ble_address_resolved,
            { "Address Resolved", "nordic_ble.address_resolved",
                FT_BOOLEAN, 8, TFS(&tfs_yes_no), 0x08,
                NULL, HFILL }
        },
        { &hf_nordic_ble_le_phy,
            { "PHY", "nordic_ble.phy",
                FT_UINT8, BASE_DEC, VALS(le_phys), 0x70,
                "Physical Layer", HFILL }
        },
        { &hf_nordic_ble_flag_reserved7,
            { "Reserved", "nordic_ble.flag_reserved7",
                FT_UINT8, BASE_DEC, NULL, 0x80,
                "Reserved for Future Use", HFILL }
        },
        { &hf_nordic_ble_channel,
            { "Channel Index", "nordic_ble.channel",
                FT_UINT8, BASE_DEC, NULL, 0x0,
                NULL, HFILL }
        },
        { &hf_nordic_ble_rssi,
            { "RSSI", "nordic_ble.rssi",
                FT_INT8, BASE_DEC | BASE_UNIT_STRING, &units_dbm, 0x0,
                "Received Signal Strength Indicator", HFILL }
        },
        { &hf_nordic_ble_event_counter,
            { "Event counter", "nordic_ble.event_counter",
                FT_UINT16, BASE_DEC, NULL, 0x0,
                NULL, HFILL }
        },
        { &hf_nordic_ble_time,
            { "Timestamp", "nordic_ble.time",
                FT_UINT32, BASE_DEC | BASE_UNIT_STRING, &units_microseconds, 0x0,
                "Firmware timestamp", HFILL }
        },
        { &hf_nordic_ble_delta_time,
            { "Delta time (end to start)", "nordic_ble.delta_time",
                FT_UINT32, BASE_DEC | BASE_UNIT_STRING, &units_microseconds, 0x0,
                "Time since end of last reported packet", HFILL }
        },
        { &hf_nordic_ble_delta_time_ss,
            { "Delta time (start to start)", "nordic_ble.delta_time_ss",
                FT_UINT32, BASE_DEC | BASE_UNIT_STRING, &units_microseconds, 0x0,
                "Time since start of last reported packet", HFILL }
        },
        { &hf_nordic_ble_packet_time,
            { "Packet time (start to end)", "nordic_ble.packet_time",
                FT_UINT32, BASE_DEC | BASE_UNIT_STRING, &units_microseconds, 0x0,
                "Time of packet", HFILL }
        },
    };

    static gint *ett[] = {
        &ett_nordic_ble,
        &ett_packet_header,
        &ett_flags
    };

    static ei_register_info ei[] = {
        { &ei_nordic_ble_bad_crc, { "nordic_ble.crc.bad", PI_CHECKSUM, PI_ERROR, "CRC is bad", EXPFILL }},
        { &ei_nordic_ble_bad_mic, { "nordic_ble.mic.bad", PI_CHECKSUM, PI_ERROR, "MIC is bad", EXPFILL }},
        { &ei_nordic_ble_bad_length, { "nordic_ble.length.bad", PI_MALFORMED, PI_ERROR, "Length is incorrect", EXPFILL }},
        { &ei_nordic_ble_unknown_version, { "nordic_ble.protover.bad", PI_PROTOCOL, PI_ERROR, "Unknown version", EXPFILL }},
    };

    expert_module_t *expert_nordic_ble;

    packet_time_context_tree = wmem_tree_new_autoreset(wmem_epan_scope(), wmem_file_scope());

    proto_nordic_ble = proto_register_protocol("nRF Sniffer for Bluetooth LE", "NORDIC_BLE", "nordic_ble");

    nordic_ble_handle = register_dissector("nordic_ble", dissect_nordic_ble, proto_nordic_ble);

    expert_nordic_ble = expert_register_protocol(proto_nordic_ble);
    expert_register_field_array(expert_nordic_ble, ei, array_length(ei));

    proto_register_field_array(proto_nordic_ble, hf, array_length(hf));
    proto_register_subtree_array(ett, array_length(ett));
}

void
proto_reg_handoff_nordic_ble(void)
{
    btle_dissector_handle = find_dissector("btle");
    debug_handle = find_dissector("nordic_debug");

    dissector_add_for_decode_as_with_preference("udp.port", nordic_ble_handle);
    dissector_add_uint("wtap_encap", WTAP_ENCAP_NORDIC_BLE, nordic_ble_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:
 */