packet-ppi.c

/*
 * packet-ppi.c
 * Routines for PPI Packet Header dissection
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 2007 Gerald Combs
 *
 * Copyright (c) 2006 CACE Technologies, Davis (California)
 * All rights reserved.
 *
 * SPDX-License-Identifier: (BSD-3-Clause OR GPL-2.0-only)
 *
 *
 * Dustin Johnson - Dustin@Dustinj.us, Dustin.Johnson@cacetech.com
 *     May 7, 2008 - Added 'Aggregation Extension' and '802.3 Extension'
 */


#include "config.h"

#include <epan/packet.h>
#include <epan/capture_dissectors.h>
#include <epan/exceptions.h>
#include <epan/ptvcursor.h>
#include <epan/prefs.h>
#include <epan/expert.h>
#include <epan/reassemble.h>
#include <wsutil/802_11-utils.h>
#include <wsutil/pint.h>
#include <wsutil/str_util.h>

/*
 * Per-Packet Information (PPI) header.
 * See the PPI Packet Header documentation at
 *
 *     https://wayback.archive.org/web/20120525190041/https://www.cacetech.com/documents/PPI%20Header%20format%201.0.10.pdf
 *
 * for details.
 */

/*
 * PPI headers have the following format:
 *
 * ,---------------------------------------------------------.
 * | PPH | PFH 1 | Field data 1 | PFH 2 | Field data 2 | ... |
 * `---------------------------------------------------------'
 *
 * The PPH struct has the following format:
 *
 * typedef struct ppi_packetheader {
 *     guint8  pph_version;     // Version.  Currently 0
 *     guint8  pph_flags;       // Flags.
 *     guint16 pph_len; // Length of entire message, including this header and TLV payload.
 *     guint32 pph_dlt; // libpcap Data Link Type of the captured packet data.
 * } ppi_packetheader_t;
 *
 * The PFH struct has the following format:
 *
 * typedef struct ppi_fieldheader {
 *     guint16 pfh_type;        // Type
 *     guint16 pfh_datalen;     // Length of data
 * } ppi_fieldheader_t;
 *
 * Anyone looking to add their own PPI dissector would probably do well to imitate the GPS
 * ones separation into a distinct file.  Here is a step by step guide:
 * 1) add the number you received to the enum ppi_field_type declaration.
 * 2) Add a value string for your number into vs_ppi_field_type
 * 3) declare a dissector handle by the ppi_gps_handle, and initialize it inside proto_reg_handoff
 * 4) add  case inside dissect_ppi to call your new handle.
 * 5) Write your parser, and get it loaded.
 * Following these steps will result in less churn inside the ppi proper parser, and avoid namespace issues.
 */


#define PPI_PADDED (1 << 0)

#define PPI_V0_HEADER_LEN 8
#define PPI_80211_COMMON_LEN 20
#define PPI_80211N_MAC_LEN 12
#define PPI_80211N_MAC_PHY_OFF 9
#define PPI_80211N_MAC_PHY_LEN 48
#define PPI_AGGREGATION_EXTENSION_LEN 4
#define PPI_8023_EXTENSION_LEN 8

#define PPI_FLAG_ALIGN 0x01
#define IS_PPI_FLAG_ALIGN(x) ((x) & PPI_FLAG_ALIGN)

#define DOT11_FLAG_HAVE_FCS     0x0001
#define DOT11_FLAG_TSF_TIMER_MS 0x0002
#define DOT11_FLAG_FCS_INVALID  0x0004
#define DOT11_FLAG_PHY_ERROR    0x0008

#define DOT11N_FLAG_GREENFIELD      0x0001
#define DOT11N_FLAG_HT40            0x0002
#define DOT11N_FLAG_SHORT_GI        0x0004
#define DOT11N_FLAG_DUPLICATE_RX    0x0008
#define DOT11N_FLAG_IS_AGGREGATE    0x0010
#define DOT11N_FLAG_MORE_AGGREGATES 0x0020
#define DOT11N_FLAG_AGG_CRC_ERROR   0x0040

#define DOT11N_IS_AGGREGATE(flags)      (flags & DOT11N_FLAG_IS_AGGREGATE)
#define DOT11N_MORE_AGGREGATES(flags)   ( \
    (flags & DOT11N_FLAG_MORE_AGGREGATES) && \
    !(flags & DOT11N_FLAG_AGG_CRC_ERROR))
#define AGGREGATE_MAX 65535
#define AMPDU_MAX 16383

/* XXX - Start - Copied from packet-radiotap.c */
/* Channel flags. */
#define IEEE80211_CHAN_TURBO    0x0010  /* Turbo channel */
#define IEEE80211_CHAN_CCK      0x0020  /* CCK channel */
#define IEEE80211_CHAN_OFDM     0x0040  /* OFDM channel */
#define IEEE80211_CHAN_2GHZ     0x0080  /* 2 GHz spectrum channel. */
#define IEEE80211_CHAN_5GHZ     0x0100  /* 5 GHz spectrum channel */
#define IEEE80211_CHAN_PASSIVE  0x0200  /* Only passive scan allowed */
#define IEEE80211_CHAN_DYN      0x0400  /* Dynamic CCK-OFDM channel */
#define IEEE80211_CHAN_GFSK     0x0800  /* GFSK channel (FHSS PHY) */

#define	IEEE80211_CHAN_ALL \
	(IEEE80211_CHAN_2GHZ | IEEE80211_CHAN_5GHZ | IEEE80211_CHAN_GFSK | \
         IEEE80211_CHAN_CCK | IEEE80211_CHAN_OFDM | IEEE80211_CHAN_DYN)
#define	IEEE80211_CHAN_ALLTURBO \
	(IEEE80211_CHAN_ALL | IEEE80211_CHAN_TURBO)

/*
 * Useful combinations of channel characteristics.
 */
#define IEEE80211_CHAN_FHSS \
        (IEEE80211_CHAN_2GHZ | IEEE80211_CHAN_GFSK)
#define	IEEE80211_CHAN_DSSS \
	(IEEE80211_CHAN_2GHZ)
#define IEEE80211_CHAN_A \
        (IEEE80211_CHAN_5GHZ | IEEE80211_CHAN_OFDM)
#define IEEE80211_CHAN_B \
        (IEEE80211_CHAN_2GHZ | IEEE80211_CHAN_CCK)
#define IEEE80211_CHAN_PUREG \
        (IEEE80211_CHAN_2GHZ | IEEE80211_CHAN_OFDM)
#define IEEE80211_CHAN_G \
        (IEEE80211_CHAN_2GHZ | IEEE80211_CHAN_DYN)
#define	IEEE80211_CHAN_108A \
	(IEEE80211_CHAN_A | IEEE80211_CHAN_TURBO)
#define IEEE80211_CHAN_108G \
        (IEEE80211_CHAN_G | IEEE80211_CHAN_TURBO)
#define IEEE80211_CHAN_108PUREG \
        (IEEE80211_CHAN_PUREG | IEEE80211_CHAN_TURBO)
/* XXX - End - Copied from packet-radiotap.c */

void proto_register_ppi(void);
void proto_reg_handoff_ppi(void);

typedef enum {
    /* 0 - 29999: Public types */
    PPI_80211_COMMON          =  2,
    PPI_80211N_MAC            =  3,
    PPI_80211N_MAC_PHY        =  4,
    PPI_SPECTRUM_MAP          =  5,
    PPI_PROCESS_INFO          =  6,
    PPI_CAPTURE_INFO          =  7,
    PPI_AGGREGATION_EXTENSION =  8,
    PPI_8023_EXTENSION        =  9,
    /* 11 - 29999: RESERVED */

    /* 30000 - 65535: Private types */
    INTEL_CORP_PRIVATE           = 30000,
    MOHAMED_THAGA_PRIVATE        = 30001,
    PPI_GPS_INFO                 = 30002, /* 30002 - 30005 described in PPI-GEOLOCATION specifcation */
    PPI_VECTOR_INFO              = 30003, /* currently available in draft from. jellch@harris.com */
    PPI_SENSOR_INFO              = 30004,
    PPI_ANTENNA_INFO             = 30005,
    FNET_PRIVATE                 = 0xC017,
    CACE_PRIVATE                 = 0xCACE
    /* All others RESERVED.  Contact the WinPcap team for an assignment */
} ppi_field_type;

/* Protocol */
static int proto_ppi = -1;

/* Packet header */
static int hf_ppi_head_version = -1;
static int hf_ppi_head_flags = -1;
static int hf_ppi_head_flag_alignment = -1;
static int hf_ppi_head_flag_reserved = -1;
static int hf_ppi_head_len = -1;
static int hf_ppi_head_dlt = -1;

/* Field header */
static int hf_ppi_field_type = -1;
static int hf_ppi_field_len = -1;

/* 802.11 Common */
static int hf_80211_common_tsft = -1;
static int hf_80211_common_flags = -1;
static int hf_80211_common_flags_fcs = -1;
static int hf_80211_common_flags_tsft = -1;
static int hf_80211_common_flags_fcs_valid = -1;
static int hf_80211_common_flags_phy_err = -1;
static int hf_80211_common_rate = -1;
static int hf_80211_common_chan_freq = -1;
static int hf_80211_common_chan_flags = -1;

static int hf_80211_common_chan_flags_turbo = -1;
static int hf_80211_common_chan_flags_cck = -1;
static int hf_80211_common_chan_flags_ofdm = -1;
static int hf_80211_common_chan_flags_2ghz = -1;
static int hf_80211_common_chan_flags_5ghz = -1;
static int hf_80211_common_chan_flags_passive = -1;
static int hf_80211_common_chan_flags_dynamic = -1;
static int hf_80211_common_chan_flags_gfsk = -1;

static int hf_80211_common_fhss_hopset = -1;
static int hf_80211_common_fhss_pattern = -1;
static int hf_80211_common_dbm_antsignal = -1;
static int hf_80211_common_dbm_antnoise = -1;

/* 802.11n MAC */
static int hf_80211n_mac_flags = -1;
static int hf_80211n_mac_flags_greenfield = -1;
static int hf_80211n_mac_flags_ht20_40 = -1;
static int hf_80211n_mac_flags_rx_guard_interval = -1;
static int hf_80211n_mac_flags_duplicate_rx = -1;
static int hf_80211n_mac_flags_more_aggregates = -1;
static int hf_80211n_mac_flags_aggregate = -1;
static int hf_80211n_mac_flags_delimiter_crc_after = -1;
static int hf_80211n_mac_ampdu_id = -1;
static int hf_80211n_mac_num_delimiters = -1;
static int hf_80211n_mac_reserved = -1;

/* 802.11n MAC+PHY */
static int hf_80211n_mac_phy_mcs = -1;
static int hf_80211n_mac_phy_num_streams = -1;
static int hf_80211n_mac_phy_rssi_combined = -1;
static int hf_80211n_mac_phy_rssi_ant0_ctl = -1;
static int hf_80211n_mac_phy_rssi_ant1_ctl = -1;
static int hf_80211n_mac_phy_rssi_ant2_ctl = -1;
static int hf_80211n_mac_phy_rssi_ant3_ctl = -1;
static int hf_80211n_mac_phy_rssi_ant0_ext = -1;
static int hf_80211n_mac_phy_rssi_ant1_ext = -1;
static int hf_80211n_mac_phy_rssi_ant2_ext = -1;
static int hf_80211n_mac_phy_rssi_ant3_ext = -1;
static int hf_80211n_mac_phy_ext_chan_freq = -1;
static int hf_80211n_mac_phy_ext_chan_flags = -1;
static int hf_80211n_mac_phy_ext_chan_flags_turbo = -1;
static int hf_80211n_mac_phy_ext_chan_flags_cck = -1;
static int hf_80211n_mac_phy_ext_chan_flags_ofdm = -1;
static int hf_80211n_mac_phy_ext_chan_flags_2ghz = -1;
static int hf_80211n_mac_phy_ext_chan_flags_5ghz = -1;
static int hf_80211n_mac_phy_ext_chan_flags_passive = -1;
static int hf_80211n_mac_phy_ext_chan_flags_dynamic = -1;
static int hf_80211n_mac_phy_ext_chan_flags_gfsk = -1;
static int hf_80211n_mac_phy_dbm_ant0signal = -1;
static int hf_80211n_mac_phy_dbm_ant0noise = -1;
static int hf_80211n_mac_phy_dbm_ant1signal = -1;
static int hf_80211n_mac_phy_dbm_ant1noise = -1;
static int hf_80211n_mac_phy_dbm_ant2signal = -1;
static int hf_80211n_mac_phy_dbm_ant2noise = -1;
static int hf_80211n_mac_phy_dbm_ant3signal = -1;
static int hf_80211n_mac_phy_dbm_ant3noise = -1;
static int hf_80211n_mac_phy_evm0 = -1;
static int hf_80211n_mac_phy_evm1 = -1;
static int hf_80211n_mac_phy_evm2 = -1;
static int hf_80211n_mac_phy_evm3 = -1;

/* 802.11n-Extensions A-MPDU fragments */
static int hf_ampdu_reassembled_in = -1;
/* static int hf_ampdu_segments = -1; */
static int hf_ampdu_segment = -1;
static int hf_ampdu_count  = -1;

/* Spectrum-Map */
static int hf_spectrum_map = -1;

/* Process-Info */
static int hf_process_info = -1;

/* Capture-Info */
static int hf_capture_info = -1;

/* Aggregation Extension */
static int hf_aggregation_extension_interface_id = -1;

/* 802.3 Extension */
static int hf_8023_extension_flags = -1;
static int hf_8023_extension_flags_fcs_present = -1;
static int hf_8023_extension_errors = -1;
static int hf_8023_extension_errors_fcs = -1;
static int hf_8023_extension_errors_sequence = -1;
static int hf_8023_extension_errors_symbol = -1;
static int hf_8023_extension_errors_data = -1;

/* Generated from convert_proto_tree_add_text.pl */
static int hf_ppi_antenna = -1;
static int hf_ppi_harris = -1;
static int hf_ppi_reserved = -1;
static int hf_ppi_vector = -1;
static int hf_ppi_fnet = -1;
static int hf_ppi_gps = -1;

static gint ett_ppi_pph = -1;
static gint ett_ppi_flags = -1;
static gint ett_dot11_common = -1;
static gint ett_dot11_common_flags = -1;
static gint ett_dot11_common_channel_flags = -1;
static gint ett_dot11n_mac = -1;
static gint ett_dot11n_mac_flags = -1;
static gint ett_dot11n_mac_phy = -1;
static gint ett_dot11n_mac_phy_ext_channel_flags = -1;
static gint ett_ampdu_segments = -1;
static gint ett_ampdu = -1;
static gint ett_ampdu_segment  = -1;
static gint ett_aggregation_extension = -1;
static gint ett_8023_extension = -1;
static gint ett_8023_extension_flags = -1;
static gint ett_8023_extension_errors = -1;

/* Generated from convert_proto_tree_add_text.pl */
static expert_field ei_ppi_invalid_length = EI_INIT;

static dissector_handle_t ppi_handle;

static dissector_handle_t ieee80211_radio_handle;
static dissector_handle_t pcap_pktdata_handle;
static dissector_handle_t ppi_gps_handle, ppi_vector_handle, ppi_sensor_handle, ppi_antenna_handle;
static dissector_handle_t ppi_fnet_handle;

static const true_false_string tfs_ppi_head_flag_alignment = { "32-bit aligned", "Not aligned" };
static const true_false_string tfs_tsft_ms = { "milliseconds", "microseconds" };
static const true_false_string tfs_ht20_40 = { "HT40", "HT20" };
static const true_false_string tfs_phy_error = { "PHY error", "No errors"};

static const value_string vs_ppi_field_type[] = {
    {PPI_80211_COMMON,          "802.11-Common"},
    {PPI_80211N_MAC,            "802.11n MAC Extensions"},
    {PPI_80211N_MAC_PHY,        "802.11n MAC+PHY Extensions"},
    {PPI_SPECTRUM_MAP,          "Spectrum-Map"},
    {PPI_PROCESS_INFO,          "Process-Info"},
    {PPI_CAPTURE_INFO,          "Capture-Info"},
    {PPI_AGGREGATION_EXTENSION, "Aggregation Extension"},
    {PPI_8023_EXTENSION,        "802.3 Extension"},

    {INTEL_CORP_PRIVATE,        "Intel Corporation (private)"},
    {MOHAMED_THAGA_PRIVATE,     "Mohamed Thaga (private)"},
    {PPI_GPS_INFO,              "GPS Tagging"},
    {PPI_VECTOR_INFO,           "Vector Tagging"},
    {PPI_SENSOR_INFO,           "Sensor tagging"},
    {PPI_ANTENNA_INFO,          "Antenna Tagging"},
    {FNET_PRIVATE,              "FlukeNetworks (private)"},
    {CACE_PRIVATE,              "CACE Technologies (private)"},
    {0, NULL}
};

/* Table for A-MPDU reassembly */
static reassembly_table ampdu_reassembly_table;

/* Reassemble A-MPDUs? */
static gboolean ppi_ampdu_reassemble = TRUE;


static gboolean
capture_ppi(const guchar *pd, int offset _U_, int len, capture_packet_info_t *cpinfo, const union wtap_pseudo_header *pseudo_header _U_)
{
    guint32  dlt;
    guint    ppi_len;

    ppi_len = pletoh16(pd+2);
    if(ppi_len < PPI_V0_HEADER_LEN || !BYTES_ARE_IN_FRAME(0, len, ppi_len))
        return FALSE;

    dlt = pletoh32(pd+4);

    return try_capture_dissector("ppi", dlt, pd, ppi_len, len, cpinfo, pseudo_header);
}

static void
ptvcursor_add_invalid_check(ptvcursor_t *csr, int hf, gint len, guint64 invalid_val) {
    proto_item *ti;
    guint64     val = invalid_val;

    switch (len) {
        case 8:
            val = tvb_get_letoh64(ptvcursor_tvbuff(csr),
                ptvcursor_current_offset(csr));
            break;
        case 4:
            val = tvb_get_letohl(ptvcursor_tvbuff(csr),
                ptvcursor_current_offset(csr));
            break;
        case 2:
            val = tvb_get_letohs(ptvcursor_tvbuff(csr),
                ptvcursor_current_offset(csr));
            break;
        case 1:
            val = tvb_get_guint8(ptvcursor_tvbuff(csr),
                ptvcursor_current_offset(csr));
            break;
        default:
            DISSECTOR_ASSERT_NOT_REACHED();
    }

    ti = ptvcursor_add(csr, hf, len, ENC_LITTLE_ENDIAN);
    if (val == invalid_val)
        proto_item_append_text(ti, " [invalid]");
}

static void
add_ppi_field_header(tvbuff_t *tvb, proto_tree *tree, int *offset)
{
    ptvcursor_t *csr;

    csr = ptvcursor_new(wmem_packet_scope(), tree, tvb, *offset);
    ptvcursor_add(csr, hf_ppi_field_type, 2, ENC_LITTLE_ENDIAN);
    ptvcursor_add(csr, hf_ppi_field_len, 2, ENC_LITTLE_ENDIAN);
    ptvcursor_free(csr);
    *offset=ptvcursor_current_offset(csr);
}

/* XXX - The main dissection function in the 802.11 dissector has the same name. */
static void
dissect_80211_common(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int offset, int data_len, struct ieee_802_11_phdr *phdr)
{
    proto_tree  *ftree;
    proto_item  *ti;
    ptvcursor_t *csr;
    guint64      tsft_raw;
    guint        rate_raw;
    guint        rate_kbps;
    guint32      common_flags;
    guint16      common_frequency;
    guint16      chan_flags;
    gint8        dbm_value;
    gchar       *chan_str;

    ftree = proto_tree_add_subtree(tree, tvb, offset, data_len, ett_dot11_common, NULL, "802.11-Common");
    add_ppi_field_header(tvb, ftree, &offset);
    data_len -= 4; /* Subtract field header length */

    if (data_len != PPI_80211_COMMON_LEN) {
        proto_tree_add_expert_format(ftree, pinfo, &ei_ppi_invalid_length, tvb, offset, data_len, "Invalid length: %u", data_len);
        return;
    }

    common_flags = tvb_get_letohs(tvb, offset + 8);
    if (common_flags & DOT11_FLAG_HAVE_FCS)
        phdr->fcs_len = 4;
    else
        phdr->fcs_len = 0;

    csr = ptvcursor_new(pinfo->pool, ftree, tvb, offset);

    tsft_raw = tvb_get_letoh64(tvb, offset);
    if (tsft_raw != 0) {
        phdr->has_tsf_timestamp = TRUE;
        if (common_flags & DOT11_FLAG_TSF_TIMER_MS)
            phdr->tsf_timestamp = tsft_raw * 1000;
        else
            phdr->tsf_timestamp = tsft_raw;
    }

    ptvcursor_add_invalid_check(csr, hf_80211_common_tsft, 8, 0);

    ptvcursor_add_with_subtree(csr, hf_80211_common_flags, 2, ENC_LITTLE_ENDIAN,
                               ett_dot11_common_flags);
    ptvcursor_add_no_advance(csr, hf_80211_common_flags_fcs, 2, ENC_LITTLE_ENDIAN);
    ptvcursor_add_no_advance(csr, hf_80211_common_flags_tsft, 2, ENC_LITTLE_ENDIAN);
    ptvcursor_add_no_advance(csr, hf_80211_common_flags_fcs_valid, 2, ENC_LITTLE_ENDIAN);
    ptvcursor_add(csr, hf_80211_common_flags_phy_err, 2, ENC_LITTLE_ENDIAN);
    ptvcursor_pop_subtree(csr);

    rate_raw = tvb_get_letohs(tvb, ptvcursor_current_offset(csr));
    if (rate_raw != 0) {
        phdr->has_data_rate = TRUE;
        phdr->data_rate = rate_raw;
    }
    rate_kbps = rate_raw * 500;
    ti = proto_tree_add_uint_format(ftree, hf_80211_common_rate, tvb,
                                    ptvcursor_current_offset(csr), 2, rate_kbps, "Rate: %.1f Mbps",
                                    rate_kbps / 1000.0);
    if (rate_kbps == 0)
        proto_item_append_text(ti, " [invalid]");
    col_add_fstr(pinfo->cinfo, COL_TX_RATE, "%.1f Mbps", rate_kbps / 1000.0);
    ptvcursor_advance(csr, 2);

    common_frequency = tvb_get_letohs(ptvcursor_tvbuff(csr), ptvcursor_current_offset(csr));
    if (common_frequency != 0) {
        gint calc_channel;

        phdr->has_frequency = TRUE;
        phdr->frequency = common_frequency;
        calc_channel = ieee80211_mhz_to_chan(common_frequency);
        if (calc_channel != -1) {
            phdr->has_channel = TRUE;
            phdr->channel = calc_channel;
        }
    }
    chan_str = ieee80211_mhz_to_str(common_frequency);
    proto_tree_add_uint_format_value(ptvcursor_tree(csr), hf_80211_common_chan_freq, ptvcursor_tvbuff(csr),
                               ptvcursor_current_offset(csr), 2, common_frequency, "%s", chan_str);
    col_add_fstr(pinfo->cinfo, COL_FREQ_CHAN, "%s", chan_str);
    g_free(chan_str);
    ptvcursor_advance(csr, 2);

    memset(&phdr->phy_info, 0, sizeof(phdr->phy_info));
    chan_flags = tvb_get_letohs(ptvcursor_tvbuff(csr), ptvcursor_current_offset(csr));
    switch (chan_flags & IEEE80211_CHAN_ALLTURBO) {

    case IEEE80211_CHAN_FHSS:
        phdr->phy = PHDR_802_11_PHY_11_FHSS;
        break;

    case IEEE80211_CHAN_DSSS:
        phdr->phy = PHDR_802_11_PHY_11_DSSS;
        break;

    case IEEE80211_CHAN_A:
        phdr->phy = PHDR_802_11_PHY_11A;
        phdr->phy_info.info_11a.has_turbo_type = TRUE;
        phdr->phy_info.info_11a.turbo_type = PHDR_802_11A_TURBO_TYPE_NORMAL;
        break;

    case IEEE80211_CHAN_B:
        phdr->phy = PHDR_802_11_PHY_11B;
        break;

    case IEEE80211_CHAN_PUREG:
        phdr->phy = PHDR_802_11_PHY_11G;
        phdr->phy_info.info_11g.has_mode = TRUE;
        phdr->phy_info.info_11g.mode = PHDR_802_11G_MODE_NORMAL;
        break;

    case IEEE80211_CHAN_G:
        phdr->phy = PHDR_802_11_PHY_11G;
        phdr->phy_info.info_11g.has_mode = TRUE;
        phdr->phy_info.info_11g.mode = PHDR_802_11G_MODE_NORMAL;
        break;

    case IEEE80211_CHAN_108A:
        phdr->phy = PHDR_802_11_PHY_11A;
        phdr->phy_info.info_11a.has_turbo_type = TRUE;
        /* We assume non-STURBO is dynamic turbo */
        phdr->phy_info.info_11a.turbo_type = PHDR_802_11A_TURBO_TYPE_DYNAMIC_TURBO;
        break;

    case IEEE80211_CHAN_108PUREG:
        phdr->phy = PHDR_802_11_PHY_11G;
        phdr->phy_info.info_11g.has_mode = TRUE;
        phdr->phy_info.info_11g.mode = PHDR_802_11G_MODE_SUPER_G;
        break;
    }
    ptvcursor_add_with_subtree(csr, hf_80211_common_chan_flags, 2, ENC_LITTLE_ENDIAN,
                               ett_dot11_common_channel_flags);
    ptvcursor_add_no_advance(csr, hf_80211_common_chan_flags_turbo, 2, ENC_LITTLE_ENDIAN);
    ptvcursor_add_no_advance(csr, hf_80211_common_chan_flags_cck, 2, ENC_LITTLE_ENDIAN);
    ptvcursor_add_no_advance(csr, hf_80211_common_chan_flags_ofdm, 2, ENC_LITTLE_ENDIAN);
    ptvcursor_add_no_advance(csr, hf_80211_common_chan_flags_2ghz, 2, ENC_LITTLE_ENDIAN);
    ptvcursor_add_no_advance(csr, hf_80211_common_chan_flags_5ghz, 2, ENC_LITTLE_ENDIAN);
    ptvcursor_add_no_advance(csr, hf_80211_common_chan_flags_passive, 2, ENC_LITTLE_ENDIAN);
    ptvcursor_add_no_advance(csr, hf_80211_common_chan_flags_dynamic, 2, ENC_LITTLE_ENDIAN);
    ptvcursor_add(csr, hf_80211_common_chan_flags_gfsk, 2, ENC_LITTLE_ENDIAN);
    ptvcursor_pop_subtree(csr);


    if (phdr->phy == PHDR_802_11_PHY_11_FHSS) {
        phdr->phy_info.info_11_fhss.has_hop_set = TRUE;
        phdr->phy_info.info_11_fhss.hop_set = tvb_get_guint8(ptvcursor_tvbuff(csr), ptvcursor_current_offset(csr));
    }
    ptvcursor_add(csr, hf_80211_common_fhss_hopset, 1, ENC_LITTLE_ENDIAN);
    if (phdr->phy == PHDR_802_11_PHY_11_FHSS) {
        phdr->phy_info.info_11_fhss.has_hop_pattern = TRUE;
        phdr->phy_info.info_11_fhss.hop_pattern = tvb_get_guint8(ptvcursor_tvbuff(csr), ptvcursor_current_offset(csr));
    }
    ptvcursor_add(csr, hf_80211_common_fhss_pattern, 1, ENC_LITTLE_ENDIAN);

    dbm_value = tvb_get_gint8(tvb, ptvcursor_current_offset(csr));
    if (dbm_value != -128 && dbm_value != 0) {
        /*
         * XXX - the spec says -128 is invalid, presumably meaning "use
         * -128 if you don't have the signal strength", but some captures
         * have 0 for noise, presumably meaning it's incorrectly being
         * used for "don't have it", so we check for it as well.
         */
        col_add_fstr(pinfo->cinfo, COL_RSSI, "%d dBm", dbm_value);
        phdr->has_signal_dbm = TRUE;
        phdr->signal_dbm = dbm_value;
    }
    ptvcursor_add_invalid_check(csr, hf_80211_common_dbm_antsignal, 1, 0x80); /* -128 */

    dbm_value = tvb_get_gint8(tvb, ptvcursor_current_offset(csr));
    if (dbm_value != -128 && dbm_value != 0) {
        /*
         * XXX - the spec says -128 is invalid, presumably meaning "use
         * -128 if you don't have the noise level", but some captures
         * have 0, presumably meaning it's incorrectly being used for
         * "don't have it", so we check for it as well.
         */
        phdr->has_noise_dbm = TRUE;
        phdr->noise_dbm = dbm_value;
    }
    ptvcursor_add_invalid_check(csr, hf_80211_common_dbm_antnoise, 1, 0x80);

    ptvcursor_free(csr);
}

static void
dissect_80211n_mac(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree, int offset, int data_len, gboolean add_subtree, guint32 *n_mac_flags, guint32 *ampdu_id, struct ieee_802_11_phdr *phdr)
{
    proto_tree  *ftree       = tree;
    ptvcursor_t *csr;
    guint32      flags;

    phdr->phy = PHDR_802_11_PHY_11N;

    if (add_subtree) {
        ftree = proto_tree_add_subtree(tree, tvb, offset, data_len, ett_dot11n_mac, NULL, "802.11n MAC");
        add_ppi_field_header(tvb, ftree, &offset);
        data_len -= 4; /* Subtract field header length */
    }

    if (data_len != PPI_80211N_MAC_LEN) {
        proto_tree_add_expert_format(ftree, pinfo, &ei_ppi_invalid_length, tvb, offset, data_len, "Invalid length: %u", data_len);
        return;
    }

    csr = ptvcursor_new(pinfo->pool, ftree, tvb, offset);

    flags = tvb_get_letohl(tvb, ptvcursor_current_offset(csr));
    *n_mac_flags = flags;
    phdr->phy_info.info_11n.has_bandwidth = TRUE;
    phdr->phy_info.info_11n.has_short_gi = TRUE;
    phdr->phy_info.info_11n.has_greenfield = TRUE;
    phdr->phy_info.info_11n.bandwidth = ((flags & DOT11N_FLAG_HT40) != 0);
    phdr->phy_info.info_11n.short_gi = ((flags & DOT11N_FLAG_SHORT_GI) != 0);
    phdr->phy_info.info_11n.greenfield = ((flags & DOT11N_FLAG_GREENFIELD) != 0);
    if (DOT11N_IS_AGGREGATE(flags)) {
        phdr->has_aggregate_info = 1;
        phdr->aggregate_flags = 0;
        if (!(flags & DOT11N_FLAG_MORE_AGGREGATES))
            phdr->aggregate_flags |= PHDR_802_11_LAST_PART_OF_A_MPDU;
        if (flags & DOT11N_FLAG_AGG_CRC_ERROR)
            phdr->aggregate_flags |= PHDR_802_11_A_MPDU_DELIM_CRC_ERROR;
    }
    ptvcursor_add_with_subtree(csr, hf_80211n_mac_flags, 4, ENC_LITTLE_ENDIAN,
                               ett_dot11n_mac_flags);
    ptvcursor_add_no_advance(csr, hf_80211n_mac_flags_greenfield, 4, ENC_LITTLE_ENDIAN);
    ptvcursor_add_no_advance(csr, hf_80211n_mac_flags_ht20_40, 4, ENC_LITTLE_ENDIAN);
    ptvcursor_add_no_advance(csr, hf_80211n_mac_flags_rx_guard_interval, 4, ENC_LITTLE_ENDIAN);
    ptvcursor_add_no_advance(csr, hf_80211n_mac_flags_duplicate_rx, 4, ENC_LITTLE_ENDIAN);
    ptvcursor_add_no_advance(csr, hf_80211n_mac_flags_aggregate, 4, ENC_LITTLE_ENDIAN);
    ptvcursor_add_no_advance(csr, hf_80211n_mac_flags_more_aggregates, 4, ENC_LITTLE_ENDIAN);
    ptvcursor_add(csr, hf_80211n_mac_flags_delimiter_crc_after, 4, ENC_LITTLE_ENDIAN); /* Last */
    ptvcursor_pop_subtree(csr);

    if (DOT11N_IS_AGGREGATE(flags)) {
        *ampdu_id = tvb_get_letohl(tvb, ptvcursor_current_offset(csr));
        phdr->aggregate_id = *ampdu_id;
    }
    ptvcursor_add(csr, hf_80211n_mac_ampdu_id, 4, ENC_LITTLE_ENDIAN);
    ptvcursor_add(csr, hf_80211n_mac_num_delimiters, 1, ENC_LITTLE_ENDIAN);

    if (add_subtree) {
        ptvcursor_add(csr, hf_80211n_mac_reserved, 3, ENC_LITTLE_ENDIAN);
    }

    ptvcursor_free(csr);
}

static void
dissect_80211n_mac_phy(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, int offset, int data_len, guint32 *n_mac_flags, guint32 *ampdu_id, struct ieee_802_11_phdr *phdr)
{
    proto_tree  *ftree;
    proto_item  *ti;
    ptvcursor_t *csr;
    guint8       mcs;
    guint8       ness;
    guint16      ext_frequency;
    gchar       *chan_str;

    ftree = proto_tree_add_subtree(tree, tvb, offset, data_len, ett_dot11n_mac_phy, NULL, "802.11n MAC+PHY");
    add_ppi_field_header(tvb, ftree, &offset);
    data_len -= 4; /* Subtract field header length */

    if (data_len != PPI_80211N_MAC_PHY_LEN) {
        proto_tree_add_expert_format(ftree, pinfo, &ei_ppi_invalid_length, tvb, offset, data_len, "Invalid length: %u", data_len);
        return;
    }

    dissect_80211n_mac(tvb, pinfo, ftree, offset, PPI_80211N_MAC_LEN,
                       FALSE, n_mac_flags, ampdu_id, phdr);
    offset += PPI_80211N_MAC_PHY_OFF;

    csr = ptvcursor_new(pinfo->pool, ftree, tvb, offset);

    mcs = tvb_get_guint8(tvb, ptvcursor_current_offset(csr));
    if (mcs != 255) {
        phdr->phy_info.info_11n.has_mcs_index = TRUE;
        phdr->phy_info.info_11n.mcs_index = mcs;
    }
    ptvcursor_add_invalid_check(csr, hf_80211n_mac_phy_mcs, 1, 255);

    ness = tvb_get_guint8(tvb, ptvcursor_current_offset(csr));
    phdr->phy_info.info_11n.has_ness = TRUE;
    phdr->phy_info.info_11n.ness = ness;
    ti = ptvcursor_add(csr, hf_80211n_mac_phy_num_streams, 1, ENC_LITTLE_ENDIAN);
    if (tvb_get_guint8(tvb, ptvcursor_current_offset(csr) - 1) == 0)
        proto_item_append_text(ti, " (unknown)");
    ptvcursor_add_invalid_check(csr, hf_80211n_mac_phy_rssi_combined, 1, 255);
    ptvcursor_add_invalid_check(csr, hf_80211n_mac_phy_rssi_ant0_ctl, 1, 255);
    ptvcursor_add_invalid_check(csr, hf_80211n_mac_phy_rssi_ant1_ctl, 1, 255);
    ptvcursor_add_invalid_check(csr, hf_80211n_mac_phy_rssi_ant2_ctl, 1, 255);
    ptvcursor_add_invalid_check(csr, hf_80211n_mac_phy_rssi_ant3_ctl, 1, 255);
    ptvcursor_add_invalid_check(csr, hf_80211n_mac_phy_rssi_ant0_ext, 1, 255);
    ptvcursor_add_invalid_check(csr, hf_80211n_mac_phy_rssi_ant1_ext, 1, 255);
    ptvcursor_add_invalid_check(csr, hf_80211n_mac_phy_rssi_ant2_ext, 1, 255);
    ptvcursor_add_invalid_check(csr, hf_80211n_mac_phy_rssi_ant3_ext, 1, 255);

    ext_frequency = tvb_get_letohs(ptvcursor_tvbuff(csr), ptvcursor_current_offset(csr));
    chan_str = ieee80211_mhz_to_str(ext_frequency);
    proto_tree_add_uint_format(ptvcursor_tree(csr), hf_80211n_mac_phy_ext_chan_freq, ptvcursor_tvbuff(csr),
                               ptvcursor_current_offset(csr), 2, ext_frequency, "Ext. Channel frequency: %s", chan_str);
    g_free(chan_str);
    ptvcursor_advance(csr, 2);

    ptvcursor_add_with_subtree(csr, hf_80211n_mac_phy_ext_chan_flags, 2, ENC_LITTLE_ENDIAN,
                               ett_dot11n_mac_phy_ext_channel_flags);
    ptvcursor_add_no_advance(csr, hf_80211n_mac_phy_ext_chan_flags_turbo, 2, ENC_LITTLE_ENDIAN);
    ptvcursor_add_no_advance(csr, hf_80211n_mac_phy_ext_chan_flags_cck, 2, ENC_LITTLE_ENDIAN);
    ptvcursor_add_no_advance(csr, hf_80211n_mac_phy_ext_chan_flags_ofdm, 2, ENC_LITTLE_ENDIAN);
    ptvcursor_add_no_advance(csr, hf_80211n_mac_phy_ext_chan_flags_2ghz, 2, ENC_LITTLE_ENDIAN);
    ptvcursor_add_no_advance(csr, hf_80211n_mac_phy_ext_chan_flags_5ghz, 2, ENC_LITTLE_ENDIAN);
    ptvcursor_add_no_advance(csr, hf_80211n_mac_phy_ext_chan_flags_passive, 2, ENC_LITTLE_ENDIAN);
    ptvcursor_add_no_advance(csr, hf_80211n_mac_phy_ext_chan_flags_dynamic, 2, ENC_LITTLE_ENDIAN);
    ptvcursor_add(csr, hf_80211n_mac_phy_ext_chan_flags_gfsk, 2, ENC_LITTLE_ENDIAN);
    ptvcursor_pop_subtree(csr);

    ptvcursor_add_invalid_check(csr, hf_80211n_mac_phy_dbm_ant0signal, 1, 0x80); /* -128 */
    ptvcursor_add_invalid_check(csr, hf_80211n_mac_phy_dbm_ant0noise, 1, 0x80);
    ptvcursor_add_invalid_check(csr, hf_80211n_mac_phy_dbm_ant1signal, 1, 0x80);
    ptvcursor_add_invalid_check(csr, hf_80211n_mac_phy_dbm_ant1noise, 1, 0x80);
    ptvcursor_add_invalid_check(csr, hf_80211n_mac_phy_dbm_ant2signal, 1, 0x80);
    ptvcursor_add_invalid_check(csr, hf_80211n_mac_phy_dbm_ant2noise, 1, 0x80);
    ptvcursor_add_invalid_check(csr, hf_80211n_mac_phy_dbm_ant3signal, 1, 0x80);
    ptvcursor_add_invalid_check(csr, hf_80211n_mac_phy_dbm_ant3noise, 1, 0x80);
    ptvcursor_add_invalid_check(csr, hf_80211n_mac_phy_evm0, 4, 0);
    ptvcursor_add_invalid_check(csr, hf_80211n_mac_phy_evm1, 4, 0);
    ptvcursor_add_invalid_check(csr, hf_80211n_mac_phy_evm2, 4, 0);
    ptvcursor_add_invalid_check(csr, hf_80211n_mac_phy_evm3, 4, 0);

    ptvcursor_free(csr);
}

static void
dissect_aggregation_extension(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree, int offset, int data_len)
{
    proto_tree *ftree;
    ptvcursor_t *csr;

    ftree = proto_tree_add_subtree(tree, tvb, offset, data_len, ett_aggregation_extension, NULL, "Aggregation Extension");
    add_ppi_field_header(tvb, ftree, &offset);
    data_len -= 4; /* Subtract field header length */

    if (data_len != PPI_AGGREGATION_EXTENSION_LEN) {
        proto_tree_add_expert_format(ftree, pinfo, &ei_ppi_invalid_length, tvb, offset, data_len, "Invalid length: %u", data_len);
        return;
    }

    csr = ptvcursor_new(pinfo->pool, ftree, tvb, offset);

    ptvcursor_add(csr, hf_aggregation_extension_interface_id, 4, ENC_LITTLE_ENDIAN); /* Last */
    ptvcursor_free(csr);
}

static void
dissect_8023_extension(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree, int offset, int data_len)
{
    proto_tree  *ftree;
    ptvcursor_t *csr;

    ftree = proto_tree_add_subtree(tree, tvb, offset, data_len, ett_8023_extension, NULL, "802.3 Extension");
    add_ppi_field_header(tvb, ftree, &offset);
    data_len -= 4; /* Subtract field header length */

    if (data_len != PPI_8023_EXTENSION_LEN) {
        proto_tree_add_expert_format(ftree, pinfo, &ei_ppi_invalid_length, tvb, offset, data_len, "Invalid length: %u", data_len);
        return;
    }

    csr = ptvcursor_new(pinfo->pool, ftree, tvb, offset);

    ptvcursor_add_with_subtree(csr, hf_8023_extension_flags, 4, ENC_LITTLE_ENDIAN, ett_8023_extension_flags);
    ptvcursor_add(csr, hf_8023_extension_flags_fcs_present, 4, ENC_LITTLE_ENDIAN);
    ptvcursor_pop_subtree(csr);

    ptvcursor_add_with_subtree(csr, hf_8023_extension_errors, 4, ENC_LITTLE_ENDIAN, ett_8023_extension_errors);
    ptvcursor_add_no_advance(csr, hf_8023_extension_errors_fcs, 4, ENC_LITTLE_ENDIAN);
    ptvcursor_add_no_advance(csr, hf_8023_extension_errors_sequence, 4, ENC_LITTLE_ENDIAN);
    ptvcursor_add_no_advance(csr, hf_8023_extension_errors_symbol, 4, ENC_LITTLE_ENDIAN);
    ptvcursor_add(csr, hf_8023_extension_errors_data, 4, ENC_LITTLE_ENDIAN);
    ptvcursor_pop_subtree(csr);

    ptvcursor_free(csr);
}


#define PADDING4(x) ((((x + 3) >> 2) << 2) - x)
#define ADD_BASIC_TAG(hf_tag) \
    if (tree)   \
        proto_tree_add_item(ppi_tree, hf_tag, tvb, offset, data_len, ENC_NA)

static int
dissect_ppi(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
    proto_tree    *ppi_tree    = NULL, *ppi_flags_tree = NULL, *seg_tree = NULL, *ampdu_tree = NULL;
    proto_tree    *agg_tree    = NULL;
    proto_item    *ti          = NULL;
    tvbuff_t      *next_tvb;
    int            offset      = 0;
    guint          version, flags;
    gint           tot_len, data_len;
    guint          data_type;
    guint32        dlt;
    guint32        n_ext_flags = 0;
    guint32        ampdu_id    = 0;
    fragment_head *fd_head     = NULL;
    fragment_item *ft_fdh      = NULL;
    gint           mpdu_count  = 0;
    gchar         *mpdu_str;
    gboolean       first_mpdu  = TRUE;
    guint          last_frame  = 0;
    gint len_remain, /*pad_len = 0,*/ ampdu_len = 0;
    struct ieee_802_11_phdr phdr;

    col_set_str(pinfo->cinfo, COL_PROTOCOL, "PPI");
    col_clear(pinfo->cinfo, COL_INFO);

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

    tot_len = tvb_get_letohs(tvb, offset+2);
    dlt = tvb_get_letohl(tvb, offset+4);

    col_add_fstr(pinfo->cinfo, COL_INFO, "PPI version %u, %u bytes",
                 version, tot_len);

    /* Dissect the packet */
    if (tree) {
        ti = proto_tree_add_protocol_format(tree, proto_ppi,
                                            tvb, 0, tot_len, "PPI version %u, %u bytes", version, tot_len);
        ppi_tree = proto_item_add_subtree(ti, ett_ppi_pph);
        proto_tree_add_item(ppi_tree, hf_ppi_head_version,
                            tvb, offset, 1, ENC_LITTLE_ENDIAN);

        ti = proto_tree_add_item(ppi_tree, hf_ppi_head_flags,
                                 tvb, offset + 1, 1, ENC_LITTLE_ENDIAN);
        ppi_flags_tree = proto_item_add_subtree(ti, ett_ppi_flags);
        proto_tree_add_item(ppi_flags_tree, hf_ppi_head_flag_alignment,
                            tvb, offset + 1, 1, ENC_LITTLE_ENDIAN);
        proto_tree_add_item(ppi_flags_tree, hf_ppi_head_flag_reserved,
                            tvb, offset + 1, 1, ENC_LITTLE_ENDIAN);

        proto_tree_add_item(ppi_tree, hf_ppi_head_len,
                                 tvb, offset + 2, 2, ENC_LITTLE_ENDIAN);
        proto_tree_add_item(ppi_tree, hf_ppi_head_dlt,
                                 tvb, offset + 4, 4, ENC_LITTLE_ENDIAN);
    }

    tot_len -= PPI_V0_HEADER_LEN;
    offset += 8;

    /* We don't have any 802.11 metadata yet. */
    memset(&phdr, 0, sizeof(phdr));
    phdr.fcs_len = -1;
    phdr.decrypted = FALSE;
    phdr.datapad = FALSE;
    phdr.phy = PHDR_802_11_PHY_UNKNOWN;

    while (tot_len > 0) {
        data_type = tvb_get_letohs(tvb, offset);
        data_len = tvb_get_letohs(tvb, offset + 2) + 4;
        tot_len -= data_len;

        switch (data_type) {

        case PPI_80211_COMMON:
            dissect_80211_common(tvb, pinfo, ppi_tree, offset, data_len, &phdr);
            break;

        case PPI_80211N_MAC:
            dissect_80211n_mac(tvb, pinfo, ppi_tree, offset, data_len,
                TRUE, &n_ext_flags, &ampdu_id, &phdr);
            break;

        case PPI_80211N_MAC_PHY:
            dissect_80211n_mac_phy(tvb, pinfo, ppi_tree, offset,
                data_len, &n_ext_flags, &ampdu_id, &phdr);
            break;

        case PPI_SPECTRUM_MAP:
            ADD_BASIC_TAG(hf_spectrum_map);
            break;

        case PPI_PROCESS_INFO:
            ADD_BASIC_TAG(hf_process_info);
            break;

        case PPI_CAPTURE_INFO:
            ADD_BASIC_TAG(hf_capture_info);
            break;

        case PPI_AGGREGATION_EXTENSION:
            dissect_aggregation_extension(tvb, pinfo, ppi_tree, offset, data_len);
            break;

        case PPI_8023_EXTENSION:
            dissect_8023_extension(tvb, pinfo, ppi_tree, offset, data_len);
            break;

        case PPI_GPS_INFO:
            if (ppi_gps_handle == NULL)
            {
                proto_tree_add_item(ppi_tree, hf_ppi_gps, tvb, offset, data_len, ENC_NA);
            }
            else /* we found a suitable dissector */
            {
                /* skip over the ppi_fieldheader, and pass it off to the dedicated GPS dissetor */
                next_tvb = tvb_new_subset_length_caplen(tvb, offset + 4, data_len - 4 , -1);
                call_dissector(ppi_gps_handle, next_tvb, pinfo, ppi_tree);
            }
            break;

        case PPI_VECTOR_INFO:
            if (ppi_vector_handle == NULL)
            {
                proto_tree_add_item(ppi_tree, hf_ppi_vector, tvb, offset, data_len, ENC_NA);
            }
            else /* we found a suitable dissector */
            {
                /* skip over the ppi_fieldheader, and pass it off to the dedicated VECTOR dissetor */
                next_tvb = tvb_new_subset_length_caplen(tvb, offset + 4, data_len - 4 , -1);
                call_dissector(ppi_vector_handle, next_tvb, pinfo, ppi_tree);
            }
            break;

        case PPI_SENSOR_INFO:
            if (ppi_sensor_handle == NULL)
            {
                proto_tree_add_item(ppi_tree, hf_ppi_harris, tvb, offset, data_len, ENC_NA);
            }
            else /* we found a suitable dissector */
            {
                /* skip over the ppi_fieldheader, and pass it off to the dedicated SENSOR dissetor */
                next_tvb = tvb_new_subset_length_caplen(tvb, offset + 4, data_len - 4 , -1);
                call_dissector(ppi_sensor_handle, next_tvb, pinfo, ppi_tree);
            }
            break;

        case PPI_ANTENNA_INFO:
            if (ppi_antenna_handle == NULL)
            {
                proto_tree_add_item(ppi_tree, hf_ppi_antenna, tvb, offset, data_len, ENC_NA);
            }
            else /* we found a suitable dissector */
            {
                /* skip over the ppi_fieldheader, and pass it off to the dedicated ANTENNA dissetor */
                next_tvb = tvb_new_subset_length_caplen(tvb, offset + 4, data_len - 4 , -1);
                call_dissector(ppi_antenna_handle, next_tvb, pinfo, ppi_tree);
            }
            break;

        case FNET_PRIVATE:
            if (ppi_fnet_handle == NULL)
            {
                proto_tree_add_item(ppi_tree, hf_ppi_fnet, tvb, offset, data_len, ENC_NA);
            }
            else /* we found a suitable dissector */
            {
                /* skip over the ppi_fieldheader, and pass it off to the dedicated FNET dissetor */
                next_tvb = tvb_new_subset_length_caplen(tvb, offset + 4, data_len - 4 , -1);
                call_dissector(ppi_fnet_handle, next_tvb, pinfo, ppi_tree);
            }
            break;

        default:
            proto_tree_add_item(ppi_tree, hf_ppi_reserved, tvb, offset, data_len, ENC_NA);
        }

        offset += data_len;
        if (IS_PPI_FLAG_ALIGN(flags)){
            offset += PADDING4(offset);
        }
    }

    /*
     * The Channel-Flags field is described as "Radiotap-formatted
     * channel flags".  The comment in the radiotap.org page about
     * the suggested xchannel field says:
     *
     *  As used, this field conflates channel properties (which
     *  need not be stored per packet but are more or less fixed)
     *  with packet properties (like the modulation).
     *
     * The radiotap channel field, in practice, seems to be used,