radiotap: Refactor some aspects of the radiotap dissector.

One thing I hate is big slabs of open coding. Compilers are very good these days
and will inline functions if they are used in only one place.

By using functions we make the code very much more readible.

There is also a big opportunity to use functions like proto_tree_add_bitmask.

Change-Id: I66d1509f577d2955996f4649e05494ab0370ed01
Reviewed-on: https://code.wireshark.org/review/24964
Petri-Dish: Richard Sharpe <realrichardsharpe@gmail.com>
Tested-by: Petri Dish Buildbot
Reviewed-by: Anders Broman <a.broman58@gmail.com>

1 files changed, 514 insertions, 448 deletions

diff --git a/epan/dissectors/packet-ieee80211-radiotap.c b/epan/dissectors/packet-ieee80211-radiotap.c
index ad915810f2..688d64822b 100644
--- a/epan/dissectors/packet-ieee80211-radiotap.c
+++ b/epan/dissectors/packet-ieee80211-radiotap.c
@@ -1113,6 +1113,490 @@ dissect_radiotap_he_info(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree
 		data6_headers, ENC_LITTLE_ENDIAN);
 }
 
+static void
+dissect_radiotap_tsft(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree,
+	int offset, struct _radiotap_info *radiotap_info,
+	struct ieee_802_11_phdr *phdr)
+{
+	radiotap_info->tsft = tvb_get_letoh64(tvb, offset);
+	phdr->tsf_timestamp = radiotap_info->tsft;
+	phdr->has_tsf_timestamp = TRUE;
+	proto_tree_add_uint64(tree, hf_radiotap_mactime, tvb, offset, 8,
+			      radiotap_info->tsft);
+}
+
+static void
+dissect_radiotap_flags(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree,
+	int offset, guint8 *rflags, struct ieee_802_11_phdr *phdr)
+{
+	proto_tree *ft;
+	proto_tree *flags_tree;
+
+	*rflags = tvb_get_guint8(tvb, offset);
+	if (*rflags & IEEE80211_RADIOTAP_F_DATAPAD)
+		phdr->datapad = TRUE;
+	if (*rflags & IEEE80211_RADIOTAP_F_FCS)
+		phdr->fcs_len = 4;
+	else
+		phdr->fcs_len = 0;
+
+	ft = proto_tree_add_item(tree, hf_radiotap_flags, tvb, offset,
+				1, ENC_BIG_ENDIAN);
+	flags_tree = proto_item_add_subtree(ft, ett_radiotap_flags);
+
+	proto_tree_add_item(flags_tree, hf_radiotap_flags_cfp, tvb, offset,
+				1, ENC_BIG_ENDIAN);
+	proto_tree_add_item(flags_tree, hf_radiotap_flags_preamble, tvb, offset,
+				1, ENC_BIG_ENDIAN);
+	proto_tree_add_item(flags_tree, hf_radiotap_flags_wep, tvb, offset, 1,
+				ENC_BIG_ENDIAN);
+	proto_tree_add_item(flags_tree, hf_radiotap_flags_frag, tvb, offset, 1,
+				ENC_BIG_ENDIAN);
+	proto_tree_add_item(flags_tree, hf_radiotap_flags_fcs, tvb, offset, 1,
+				ENC_BIG_ENDIAN);
+	proto_tree_add_item(flags_tree, hf_radiotap_flags_datapad, tvb, offset,
+				1, ENC_BIG_ENDIAN);
+	proto_tree_add_item(flags_tree, hf_radiotap_flags_badfcs, tvb, offset,
+				1, ENC_BIG_ENDIAN);
+	proto_tree_add_item(flags_tree, hf_radiotap_flags_shortgi, tvb, offset,
+				1, ENC_BIG_ENDIAN);
+}
+
+static void
+dissect_radiotap_rate(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree,
+	int offset, struct _radiotap_info *radiotap_info,
+	struct ieee_802_11_phdr *phdr)
+{
+	guint32 rate;
+
+	rate = tvb_get_guint8(tvb, offset);
+	/*
+	 * XXX On FreeBSD rate & 0x80 means we have an MCS. On
+	 * Linux and AirPcap it does not.  (What about
+	 * macOS, NetBSD, OpenBSD, and DragonFly BSD?)
+	 *
+	 * This is an issue either for proprietary extensions
+	 * to 11a or 11g, which do exist, or for 11n
+	 * implementations that stuff a rate value into
+	 * this field, which also appear to exist.
+	 */
+	if (radiotap_interpret_high_rates_as_mcs &&
+			rate >= 0x80 && rate <= (0x80+76)) {
+		/*
+		 * XXX - we don't know the channel width
+		 * or guard interval length, so we can't
+		 * convert this to a data rate.
+		 *
+		 * If you want us to show a data rate,
+		 * use the MCS field, not the Rate field;
+		 * the MCS field includes not only the
+		 * MCS index, it also includes bandwidth
+		 * and guard interval information.
+		 *
+		 * XXX - can we get the channel width
+		 * from XChannel and the guard interval
+		 * information from Flags, at least on
+		 * FreeBSD?
+		 */
+		proto_tree_add_uint(tree, hf_radiotap_mcs_index, tvb, offset,
+				1, rate & 0x7f);
+	} else {
+		col_add_fstr(pinfo->cinfo, COL_TX_RATE, "%d.%d",
+			     rate / 2, rate & 1 ? 5 : 0);
+		proto_tree_add_float_format(tree, hf_radiotap_datarate,
+					    tvb, offset, 1, (float)rate / 2,
+					    "Data Rate: %.1f Mb/s",
+					    (float)rate / 2);
+		radiotap_info->rate = rate;
+		phdr->has_data_rate = TRUE;
+		phdr->data_rate = rate;
+	}
+}
+
+static void
+dissect_radiotap_channel(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree,
+	int offset, guint8 rflags, gboolean have_rflags,
+	struct _radiotap_info *radiotap_info, struct ieee_802_11_phdr *phdr)
+{
+	guint32     freq;
+	guint16     cflags;
+
+	freq = tvb_get_letohs(tvb, offset);
+	if (freq != 0) {
+		/*
+		 * XXX - some captures have 0, which is
+		 * obviously bogus.
+		 */
+		gint calc_channel;
+
+		phdr->has_frequency = TRUE;
+		phdr->frequency = freq;
+		calc_channel = ieee80211_mhz_to_chan(freq);
+		if (calc_channel != -1) {
+			phdr->has_channel = TRUE;
+			phdr->channel = calc_channel;
+		}
+	}
+	memset(&phdr->phy_info, 0, sizeof(phdr->phy_info));
+	cflags = tvb_get_letohs(tvb, offset + 2);
+	switch (cflags & 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;
+		if (have_rflags) {
+			phdr->phy_info.info_11b.has_short_preamble = TRUE;
+			phdr->phy_info.info_11b.short_preamble = (rflags & IEEE80211_RADIOTAP_F_SHORTPRE) != 0;
+		}
+		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;
+		if (have_rflags) {
+			phdr->phy_info.info_11g.has_short_preamble = TRUE;
+			phdr->phy_info.info_11g.short_preamble = (rflags & IEEE80211_RADIOTAP_F_SHORTPRE) != 0;
+		}
+		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;
+		if (have_rflags) {
+			phdr->phy_info.info_11g.has_short_preamble = TRUE;
+			phdr->phy_info.info_11g.short_preamble = (rflags & IEEE80211_RADIOTAP_F_SHORTPRE) != 0;
+		}
+		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;
+		if (have_rflags) {
+			phdr->phy_info.info_11g.has_short_preamble = TRUE;
+			phdr->phy_info.info_11g.short_preamble = (rflags & IEEE80211_RADIOTAP_F_SHORTPRE) != 0;
+		}
+		break;
+	}
+	if (tree) {
+		gchar	   *chan_str;
+		static const int * channel_flags[] = {
+			&hf_radiotap_channel_flags_turbo,
+			&hf_radiotap_channel_flags_cck,
+			&hf_radiotap_channel_flags_ofdm,
+			&hf_radiotap_channel_flags_2ghz,
+			&hf_radiotap_channel_flags_5ghz,
+			&hf_radiotap_channel_flags_passive,
+			&hf_radiotap_channel_flags_dynamic,
+			&hf_radiotap_channel_flags_gfsk,
+			&hf_radiotap_channel_flags_gsm,
+			&hf_radiotap_channel_flags_sturbo,
+			&hf_radiotap_channel_flags_half,
+			&hf_radiotap_channel_flags_quarter,
+			NULL
+		};
+
+		chan_str = ieee80211_mhz_to_str(freq);
+		col_add_fstr(pinfo->cinfo,
+			     COL_FREQ_CHAN, "%s", chan_str);
+		proto_tree_add_uint_format_value(tree,
+					   hf_radiotap_channel_frequency,
+					   tvb, offset, 2, freq,
+					   "%s",
+					   chan_str);
+		g_free(chan_str);
+
+		/* We're already 2-byte aligned. */
+		proto_tree_add_bitmask(tree, tvb, offset + 2,
+				hf_radiotap_channel_flags,
+				ett_radiotap_channel_flags,
+				channel_flags, ENC_LITTLE_ENDIAN);
+		radiotap_info->freq = freq;
+		radiotap_info->flags = cflags;
+	}
+}
+
+static void
+dissect_radiotap_fhss(tvbuff_t *tvb, packet_info *pinfo _U_, proto_tree *tree,
+	int offset, struct _radiotap_info *radiotap_info _U_,
+	struct ieee_802_11_phdr *phdr)
+{
+	/*
+	 * Just in case we didn't have a Channel field or
+	 * it said this was something other than 11 legacy
+	 * FHSS.
+	 */
+	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(tvb, offset);
+	phdr->phy_info.info_11_fhss.has_hop_pattern = TRUE;
+	phdr->phy_info.info_11_fhss.hop_pattern = tvb_get_guint8(tvb, offset + 1);
+	proto_tree_add_item(tree, hf_radiotap_fhss_hopset, tvb, offset, 1,
+			    ENC_BIG_ENDIAN);
+	proto_tree_add_item(tree, hf_radiotap_fhss_pattern, tvb, offset + 1, 1,
+			    ENC_BIG_ENDIAN);
+}
+
+static void
+dissect_radiotap_dbm_antsignal(tvbuff_t *tvb, packet_info *pinfo _U_,
+	proto_tree *tree, int offset, struct _radiotap_info *radiotap_info,
+	struct ieee_802_11_phdr *phdr)
+{
+	gint8 dbm = (gint8)tvb_get_guint8(tvb, offset);
+
+	phdr->has_signal_dbm = TRUE;
+	phdr->signal_dbm = dbm;
+	col_add_fstr(pinfo->cinfo, COL_RSSI, "%d dBm", dbm);
+	proto_tree_add_int(tree, hf_radiotap_dbm_antsignal, tvb, offset, 1, dbm);
+	radiotap_info->dbm_antsignal = dbm;
+
+}
+
+static void
+dissect_radiotap_dbm_antnoise(tvbuff_t *tvb, packet_info *pinfo _U_,
+	proto_tree *tree, int offset, struct _radiotap_info *radiotap_info,
+	struct ieee_802_11_phdr *phdr)
+{
+	gint dbm = (gint8) tvb_get_guint8(tvb, offset);
+
+	phdr->has_noise_dbm = TRUE;
+	phdr->noise_dbm = dbm;
+	if (tree) {
+		proto_tree_add_int(tree, hf_radiotap_dbm_antnoise, tvb, offset,
+				1, dbm);
+	}
+	radiotap_info->dbm_antnoise = dbm;
+}
+
+static void
+dissect_radiotap_rx_flags(tvbuff_t *tvb, packet_info *pinfo _U_,
+	proto_tree *tree, int offset, proto_item **hdr_fcs_ti,
+	int *hdr_fcs_offset, int *sent_fcs)
+{
+	if (radiotap_bit14_fcs) {
+		if (tree) {
+			*sent_fcs   = tvb_get_ntohl(tvb, offset);
+			*hdr_fcs_ti = proto_tree_add_uint(tree,
+							 hf_radiotap_fcs, tvb,
+							 offset, 4, *sent_fcs);
+			*hdr_fcs_offset = offset;
+		}
+	} else {
+		static const int * rxflags[] = {
+			&hf_radiotap_rxflags_badplcp,
+			NULL
+		};
+
+		proto_tree_add_bitmask(tree, tvb, offset,
+				hf_radiotap_rxflags, ett_radiotap_rxflags,
+				rxflags, ENC_LITTLE_ENDIAN);
+	}
+}
+
+static void
+dissect_radiotap_xchannel(tvbuff_t *tvb, packet_info *pinfo _U_,
+	proto_tree *tree, int offset, guint8 rflags, gboolean have_rflags,
+	struct _radiotap_info *radiotap_info _U_, struct ieee_802_11_phdr *phdr)
+{
+	guint32     xcflags = tvb_get_letohl(tvb, offset);
+	guint32     freq;
+
+	switch (xcflags & IEEE80211_CHAN_ALLTURBO) {
+
+	case IEEE80211_CHAN_FHSS:
+		/*
+		 * Don't overwrite any FHSS information
+		 * we've seen before this.
+		 */
+		if (phdr->phy != PHDR_802_11_PHY_11_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;
+		if (have_rflags) {
+			phdr->phy_info.info_11b.has_short_preamble = TRUE;
+			phdr->phy_info.info_11b.short_preamble = (rflags & IEEE80211_RADIOTAP_F_SHORTPRE) != 0;
+		}
+		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;
+		if (have_rflags) {
+			phdr->phy_info.info_11g.has_short_preamble = TRUE;
+			phdr->phy_info.info_11g.short_preamble = (rflags & IEEE80211_RADIOTAP_F_SHORTPRE) != 0;
+		}
+		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;
+		if (have_rflags) {
+			phdr->phy_info.info_11g.has_short_preamble = TRUE;
+			phdr->phy_info.info_11g.short_preamble = (rflags & IEEE80211_RADIOTAP_F_SHORTPRE) != 0;
+		}
+		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;
+		if (have_rflags) {
+			phdr->phy_info.info_11g.has_short_preamble = TRUE;
+			phdr->phy_info.info_11g.short_preamble = (rflags & IEEE80211_RADIOTAP_F_SHORTPRE) != 0;
+		}
+		break;
+
+	case IEEE80211_CHAN_ST:
+		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_STATIC_TURBO;
+		break;
+
+	case IEEE80211_CHAN_A|IEEE80211_CHAN_HT20:
+	case IEEE80211_CHAN_A|IEEE80211_CHAN_HT40D:
+	case IEEE80211_CHAN_A|IEEE80211_CHAN_HT40U:
+	case IEEE80211_CHAN_G|IEEE80211_CHAN_HT20:
+	case IEEE80211_CHAN_G|IEEE80211_CHAN_HT40U:
+	case IEEE80211_CHAN_G|IEEE80211_CHAN_HT40D:
+		phdr->phy = PHDR_802_11_PHY_11N;
+
+		/*
+		 * This doesn't supply "short GI" information,
+		 * so use the 0x80 bit in the Flags field,
+		 * if we have it; it's "Currently unspecified
+		 * but used" for that purpose, according to
+		 * the radiotap.org page for that field.
+		 */
+		if (have_rflags) {
+			phdr->phy_info.info_11n.has_short_gi = TRUE;
+			if (rflags & 0x80)
+				phdr->phy_info.info_11n.short_gi = 1;
+			else
+				phdr->phy_info.info_11n.short_gi = 0;
+		}
+		break;
+	}
+	freq = tvb_get_letohs(tvb, offset + 4);
+	if (freq != 0) {
+		/*
+		 * XXX - some captures have 0, which is
+		 * obviously bogus.
+		 */
+		phdr->has_frequency = TRUE;
+		phdr->frequency = freq;
+	}
+	phdr->has_channel = TRUE;
+	phdr->channel = tvb_get_guint8(tvb, offset + 6);
+	if (tree) {
+		static const int * xchannel_flags[] = {
+			&hf_radiotap_xchannel_flags_turbo,
+			&hf_radiotap_xchannel_flags_cck,
+			&hf_radiotap_xchannel_flags_ofdm,
+			&hf_radiotap_xchannel_flags_2ghz,
+			&hf_radiotap_xchannel_flags_5ghz,
+			&hf_radiotap_xchannel_flags_passive,
+			&hf_radiotap_xchannel_flags_dynamic,
+			&hf_radiotap_xchannel_flags_gfsk,
+			&hf_radiotap_xchannel_flags_gsm,
+			&hf_radiotap_xchannel_flags_sturbo,
+			&hf_radiotap_xchannel_flags_half,
+			&hf_radiotap_xchannel_flags_quarter,
+			&hf_radiotap_xchannel_flags_ht20,
+			&hf_radiotap_xchannel_flags_ht40u,
+			&hf_radiotap_xchannel_flags_ht40d,
+			NULL
+		};
+
+		proto_tree_add_item(tree, hf_radiotap_xchannel_channel,
+					tvb, offset + 6, 1,
+					ENC_LITTLE_ENDIAN);
+		proto_tree_add_item(tree, hf_radiotap_xchannel_frequency,
+					tvb, offset + 4, 2, ENC_LITTLE_ENDIAN);
+
+		proto_tree_add_bitmask(tree, tvb, offset, hf_radiotap_xchannel_flags,
+					ett_radiotap_xchannel_flags,
+					xchannel_flags, ENC_LITTLE_ENDIAN);
+
+
+#if 0
+		proto_tree_add_uint(tree, hf_radiotap_xchannel_maxpower,
+					tvb, offset + 7, 1, maxpower);
+#endif
+	}
+}
+
+static void
+dissect_radiotap_timestamp(tvbuff_t *tvb, packet_info *pinfo _U_,
+	proto_tree *tree, int offset, struct _radiotap_info *radiotap_info _U_,
+	struct ieee_802_11_phdr *phdr _U_)
+{
+	proto_item *it_root;
+	proto_tree *ts_tree, *flg_tree;
+
+	it_root = proto_tree_add_item(tree, hf_radiotap_timestamp, tvb, offset,
+			12, ENC_NA);
+	ts_tree = proto_item_add_subtree(it_root, ett_radiotap_timestamp);
+
+	proto_tree_add_item(ts_tree, hf_radiotap_timestamp_ts, tvb, offset, 8,
+			ENC_LITTLE_ENDIAN);
+	if (tvb_get_letohs(tvb, offset + 11) & IEEE80211_RADIOTAP_TS_FLG_ACCURACY)
+		proto_tree_add_item(ts_tree, hf_radiotap_timestamp_accuracy,
+				tvb, offset + 8, 2, ENC_LITTLE_ENDIAN);
+	proto_tree_add_item(ts_tree, hf_radiotap_timestamp_unit, tvb,
+			offset + 10, 1, ENC_LITTLE_ENDIAN);
+	proto_tree_add_item(ts_tree, hf_radiotap_timestamp_spos, tvb,
+			offset + 10, 1, ENC_LITTLE_ENDIAN);
+	flg_tree = proto_item_add_subtree(ts_tree, ett_radiotap_timestamp_flags);
+	proto_tree_add_item(flg_tree, hf_radiotap_timestamp_flags_32bit, tvb,
+			offset + 11, 1, ENC_LITTLE_ENDIAN);
+	proto_tree_add_item(flg_tree, hf_radiotap_timestamp_flags_accuracy, tvb,
+			offset + 11, 1, ENC_LITTLE_ENDIAN);
+}
+
 static int
 dissect_radiotap(tvbuff_t * tvb, packet_info * pinfo, proto_tree * tree, void* unused_data _U_)
 {
@@ -1121,20 +1605,16 @@ dissect_radiotap(tvbuff_t * tvb, packet_info * pinfo, proto_tree * tree, void* u
 	proto_tree *present_tree      = NULL;
 	proto_item *present_word_item = NULL;
 	proto_tree *present_word_tree = NULL;
-	proto_tree *ft;
 	proto_item *ti                = NULL;
 	proto_item *hidden_item;
 	int         offset;
 	tvbuff_t   *next_tvb;
 	guint8      version;
 	guint       length;
-	guint16     cflags;
-	guint32     freq;
 	proto_item *rate_ti;
-	gint8       dbm, db;
+	gint8       db;
 	gboolean    have_rflags       = FALSE;
 	guint8      rflags            = 0;
-	guint32     xcflags;
 	/* backward compat with bit 14 == fcs in header */
 	proto_item *hdr_fcs_ti        = NULL;
 	int         hdr_fcs_offset    = 0;
@@ -1396,276 +1876,40 @@ dissect_radiotap(tvbuff_t * tvb, packet_info * pinfo, proto_tree * tree, void* u
 		switch (iter.this_arg_index) {
 
 		case IEEE80211_RADIOTAP_TSFT:
-			radiotap_info->tsft = tvb_get_letoh64(tvb, offset);
-			phdr.tsf_timestamp = radiotap_info->tsft;
-			phdr.has_tsf_timestamp = TRUE;
-			if (tree) {
-				proto_tree_add_uint64(radiotap_tree,
-						      hf_radiotap_mactime, tvb,
-						      offset, 8,
-						      radiotap_info->tsft);
-			}
+			dissect_radiotap_tsft(tvb, pinfo, radiotap_tree, offset,
+					radiotap_info, &phdr);
 			break;
 
-		case IEEE80211_RADIOTAP_FLAGS: {
-			rflags = tvb_get_guint8(tvb, offset);
+		case IEEE80211_RADIOTAP_FLAGS:
 			have_rflags = TRUE;
-			if (rflags & IEEE80211_RADIOTAP_F_DATAPAD)
-				phdr.datapad = TRUE;
-			if (rflags & IEEE80211_RADIOTAP_F_FCS)
-				phdr.fcs_len = 4;
-			else
-				phdr.fcs_len = 0;
-
-			if (tree) {
-				proto_tree *flags_tree;
-
-				ft = proto_tree_add_item(radiotap_tree,
-							 hf_radiotap_flags,
-							 tvb, offset, 1, ENC_BIG_ENDIAN);
-				flags_tree =
-				    proto_item_add_subtree(ft,
-							   ett_radiotap_flags);
-
-				proto_tree_add_item(flags_tree,
-						    hf_radiotap_flags_cfp,
-						    tvb, offset, 1, ENC_BIG_ENDIAN);
-				proto_tree_add_item(flags_tree,
-						    hf_radiotap_flags_preamble,
-						    tvb, offset, 1, ENC_BIG_ENDIAN);
-				proto_tree_add_item(flags_tree,
-						    hf_radiotap_flags_wep,
-						    tvb, offset, 1, ENC_BIG_ENDIAN);
-				proto_tree_add_item(flags_tree,
-						    hf_radiotap_flags_frag,
-						    tvb, offset, 1, ENC_BIG_ENDIAN);
-				proto_tree_add_item(flags_tree,
-						    hf_radiotap_flags_fcs,
-						    tvb, offset, 1, ENC_BIG_ENDIAN);
-				proto_tree_add_item(flags_tree,
-						    hf_radiotap_flags_datapad,
-						    tvb, offset, 1, ENC_BIG_ENDIAN);
-				proto_tree_add_item(flags_tree,
-						    hf_radiotap_flags_badfcs,
-						    tvb, offset, 1, ENC_BIG_ENDIAN);
-				proto_tree_add_item(flags_tree,
-						    hf_radiotap_flags_shortgi,
-						    tvb, offset, 1, ENC_BIG_ENDIAN);
-			}
+			dissect_radiotap_flags(tvb, pinfo, radiotap_tree, offset,
+					&rflags, &phdr);
 			break;
-		}
 
-		case IEEE80211_RADIOTAP_RATE: {
-			guint32 rate;
-			rate = tvb_get_guint8(tvb, offset);
-			/*
-			 * XXX On FreeBSD rate & 0x80 means we have an MCS. On
-			 * Linux and AirPcap it does not.  (What about
-			 * macOS, NetBSD, OpenBSD, and DragonFly BSD?)
-			 *
-			 * This is an issue either for proprietary extensions
-			 * to 11a or 11g, which do exist, or for 11n
-			 * implementations that stuff a rate value into
-			 * this field, which also appear to exist.
-			 */
-			if (radiotap_interpret_high_rates_as_mcs &&
-					rate >= 0x80 && rate <= (0x80+76)) {
-				/*
-				 * XXX - we don't know the channel width
-				 * or guard interval length, so we can't
-				 * convert this to a data rate.
-				 *
-				 * If you want us to show a data rate,
-				 * use the MCS field, not the Rate field;
-				 * the MCS field includes not only the
-				 * MCS index, it also includes bandwidth
-				 * and guard interval information.
-				 *
-				 * XXX - can we get the channel width
-				 * from XChannel and the guard interval
-				 * information from Flags, at least on
-				 * FreeBSD?
-				 */
-				if (tree) {
-					proto_tree_add_uint(radiotap_tree,
-							    hf_radiotap_mcs_index,
-							    tvb, offset, 1,
-							    rate & 0x7f);
-				}
-			} else {
-				col_add_fstr(pinfo->cinfo, COL_TX_RATE, "%d.%d",
-					     rate / 2, rate & 1 ? 5 : 0);
-				if (tree) {
-					proto_tree_add_float_format(radiotap_tree,
-								    hf_radiotap_datarate,
-								    tvb, offset, 1,
-								    (float)rate / 2,
-								    "Data Rate: %.1f Mb/s",
-								    (float)rate / 2);
-				}
-				radiotap_info->rate = rate;
-				phdr.has_data_rate = TRUE;
-				phdr.data_rate = rate;
-			}
+		case IEEE80211_RADIOTAP_RATE:
+			dissect_radiotap_rate(tvb, pinfo, radiotap_tree, offset,
+					radiotap_info, &phdr);
 			break;
-		}
 
-		case IEEE80211_RADIOTAP_CHANNEL: {
-			freq = tvb_get_letohs(tvb, offset);
-			if (freq != 0) {
-				/*
-				 * XXX - some captures have 0, which is
-				 * obviously bogus.
-				 */
-				gint calc_channel;
-
-				phdr.has_frequency = TRUE;
-				phdr.frequency = freq;
-				calc_channel = ieee80211_mhz_to_chan(freq);
-				if (calc_channel != -1) {
-					phdr.has_channel = TRUE;
-					phdr.channel = calc_channel;
-				}
-			}
-			memset(&phdr.phy_info, 0, sizeof(phdr.phy_info));
-			cflags = tvb_get_letohs(tvb, offset + 2);
-			switch (cflags & 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;
-				if (have_rflags) {
-					phdr.phy_info.info_11b.has_short_preamble = TRUE;
-					phdr.phy_info.info_11b.short_preamble = (rflags & IEEE80211_RADIOTAP_F_SHORTPRE) != 0;
-				}
-				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;
-				if (have_rflags) {
-					phdr.phy_info.info_11g.has_short_preamble = TRUE;
-					phdr.phy_info.info_11g.short_preamble = (rflags & IEEE80211_RADIOTAP_F_SHORTPRE) != 0;
-				}
-				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;
-				if (have_rflags) {
-					phdr.phy_info.info_11g.has_short_preamble = TRUE;
-					phdr.phy_info.info_11g.short_preamble = (rflags & IEEE80211_RADIOTAP_F_SHORTPRE) != 0;
-				}
-				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;
-				if (have_rflags) {
-					phdr.phy_info.info_11g.has_short_preamble = TRUE;
-					phdr.phy_info.info_11g.short_preamble = (rflags & IEEE80211_RADIOTAP_F_SHORTPRE) != 0;
-				}
-				break;
-			}
-			if (tree) {
-				gchar	   *chan_str;
-				static const int * channel_flags[] = {
-					&hf_radiotap_channel_flags_turbo,
-					&hf_radiotap_channel_flags_cck,
-					&hf_radiotap_channel_flags_ofdm,
-					&hf_radiotap_channel_flags_2ghz,
-					&hf_radiotap_channel_flags_5ghz,
-					&hf_radiotap_channel_flags_passive,
-					&hf_radiotap_channel_flags_dynamic,
-					&hf_radiotap_channel_flags_gfsk,
-					&hf_radiotap_channel_flags_gsm,
-					&hf_radiotap_channel_flags_sturbo,
-					&hf_radiotap_channel_flags_half,
-					&hf_radiotap_channel_flags_quarter,
-					NULL
-				};
-
-				chan_str = ieee80211_mhz_to_str(freq);
-				col_add_fstr(pinfo->cinfo,
-					     COL_FREQ_CHAN, "%s", chan_str);
-				proto_tree_add_uint_format_value(radiotap_tree,
-							   hf_radiotap_channel_frequency,
-							   tvb, offset, 2, freq,
-							   "%s",
-							   chan_str);
-				g_free(chan_str);
-
-				/* We're already 2-byte aligned. */
-				proto_tree_add_bitmask(radiotap_tree, tvb, offset + 2, hf_radiotap_channel_flags, ett_radiotap_channel_flags, channel_flags, ENC_LITTLE_ENDIAN);
-				radiotap_info->freq = freq;
-				radiotap_info->flags = cflags;
-			}
+		case IEEE80211_RADIOTAP_CHANNEL:
+			dissect_radiotap_channel(tvb, pinfo, radiotap_tree, offset,
+					rflags, have_rflags, radiotap_info,
+					&phdr);
 			break;
-		}
 
 		case IEEE80211_RADIOTAP_FHSS:
-			/*
-			 * Just in case we didn't have a Channel field or
-			 * it said this was something other than 11 legacy
-			 * FHSS.
-			 */
-			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(tvb, offset);
-			phdr.phy_info.info_11_fhss.has_hop_pattern = TRUE;
-			phdr.phy_info.info_11_fhss.hop_pattern = tvb_get_guint8(tvb, offset + 1);
-			proto_tree_add_item(radiotap_tree,
-					    hf_radiotap_fhss_hopset, tvb,
-					    offset, 1, ENC_BIG_ENDIAN);
-			proto_tree_add_item(radiotap_tree,
-					    hf_radiotap_fhss_pattern, tvb,
-					    offset + 1, 1, ENC_BIG_ENDIAN);
+			dissect_radiotap_fhss(tvb, pinfo, radiotap_tree, offset,
+					radiotap_info, &phdr);
 			break;
 
 		case IEEE80211_RADIOTAP_DBM_ANTSIGNAL:
-			dbm = (gint8)tvb_get_guint8(tvb, offset);
-			phdr.has_signal_dbm = TRUE;
-			phdr.signal_dbm = dbm;
-			col_add_fstr(pinfo->cinfo, COL_RSSI, "%d dBm", dbm);
-			proto_tree_add_int(radiotap_tree,
-							  hf_radiotap_dbm_antsignal,
-							  tvb, offset, 1, dbm);
-			radiotap_info->dbm_antsignal = dbm;
+			dissect_radiotap_dbm_antsignal(tvb, pinfo, radiotap_tree,
+					offset, radiotap_info, &phdr);
 			break;
 
 		case IEEE80211_RADIOTAP_DBM_ANTNOISE:
-			dbm = (gint8) tvb_get_guint8(tvb, offset);
-			phdr.has_noise_dbm = TRUE;
-			phdr.noise_dbm = dbm;
-			if (tree) {
-				proto_tree_add_int(radiotap_tree,
-							  hf_radiotap_dbm_antnoise,
-							  tvb, offset, 1, dbm);
-			}
-			radiotap_info->dbm_antnoise = dbm;
+			dissect_radiotap_dbm_antnoise(tvb, pinfo, radiotap_tree,
+					offset, radiotap_info, &phdr);
 			break;
 
 		case IEEE80211_RADIOTAP_LOCK_QUALITY:
@@ -1713,175 +1957,18 @@ dissect_radiotap(tvbuff_t * tvb, packet_info * pinfo, proto_tree * tree, void* u
 							   tvb, offset, 1, db);
 			break;
 
-		case IEEE80211_RADIOTAP_RX_FLAGS: {
-			if (radiotap_bit14_fcs) {
-				if (tree) {
-					sent_fcs   = tvb_get_ntohl(tvb, offset);
-					hdr_fcs_ti = proto_tree_add_uint(radiotap_tree,
-									 hf_radiotap_fcs, tvb,
-									 offset, 4, sent_fcs);
-					hdr_fcs_offset = offset;
-				}
-			} else {
-				static const int * rxflags[] = {
-					&hf_radiotap_rxflags_badplcp,
-					NULL
-				};
-
-				proto_tree_add_bitmask(radiotap_tree, tvb, offset, hf_radiotap_rxflags, ett_radiotap_rxflags, rxflags, ENC_LITTLE_ENDIAN);
-			}
+		case IEEE80211_RADIOTAP_RX_FLAGS:
+			dissect_radiotap_rx_flags(tvb, pinfo, radiotap_tree,
+						offset, &hdr_fcs_ti,
+						&hdr_fcs_offset, &sent_fcs);
 			break;
-		}
 
-		case IEEE80211_RADIOTAP_XCHANNEL: {
-			xcflags = tvb_get_letohl(tvb, offset);
-			switch (xcflags & IEEE80211_CHAN_ALLTURBO) {
-
-			case IEEE80211_CHAN_FHSS:
-				/*
-				 * Don't overwrite any FHSS information
-				 * we've seen before this.
-				 */
-				if (phdr.phy != PHDR_802_11_PHY_11_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;
-				if (have_rflags) {
-					phdr.phy_info.info_11b.has_short_preamble = TRUE;
-					phdr.phy_info.info_11b.short_preamble = (rflags & IEEE80211_RADIOTAP_F_SHORTPRE) != 0;
-				}
-				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;
-				if (have_rflags) {
-					phdr.phy_info.info_11g.has_short_preamble = TRUE;
-					phdr.phy_info.info_11g.short_preamble = (rflags & IEEE80211_RADIOTAP_F_SHORTPRE) != 0;
-				}
-				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;
-				if (have_rflags) {
-					phdr.phy_info.info_11g.has_short_preamble = TRUE;
-					phdr.phy_info.info_11g.short_preamble = (rflags & IEEE80211_RADIOTAP_F_SHORTPRE) != 0;
-				}
-				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;
-				if (have_rflags) {
-					phdr.phy_info.info_11g.has_short_preamble = TRUE;
-					phdr.phy_info.info_11g.short_preamble = (rflags & IEEE80211_RADIOTAP_F_SHORTPRE) != 0;
-				}
-				break;
-
-			case IEEE80211_CHAN_ST:
-				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_STATIC_TURBO;
-				break;
-
-			case IEEE80211_CHAN_A|IEEE80211_CHAN_HT20:
-			case IEEE80211_CHAN_A|IEEE80211_CHAN_HT40D:
-			case IEEE80211_CHAN_A|IEEE80211_CHAN_HT40U:
-			case IEEE80211_CHAN_G|IEEE80211_CHAN_HT20:
-			case IEEE80211_CHAN_G|IEEE80211_CHAN_HT40U:
-			case IEEE80211_CHAN_G|IEEE80211_CHAN_HT40D:
-				phdr.phy = PHDR_802_11_PHY_11N;
-
-				/*
-				 * This doesn't supply "short GI" information,
-				 * so use the 0x80 bit in the Flags field,
-				 * if we have it; it's "Currently unspecified
-				 * but used" for that purpose, according to
-				 * the radiotap.org page for that field.
-				 */
-				if (have_rflags) {
-					phdr.phy_info.info_11n.has_short_gi = TRUE;
-					if (rflags & 0x80)
-						phdr.phy_info.info_11n.short_gi = 1;
-					else
-						phdr.phy_info.info_11n.short_gi = 0;
-				}
-				break;
-			}
-			freq = tvb_get_letohs(tvb, offset + 4);
-			if (freq != 0) {
-				/*
-				 * XXX - some captures have 0, which is
-				 * obviously bogus.
-				 */
-				phdr.has_frequency = TRUE;
-				phdr.frequency = freq;
-			}
-			phdr.has_channel = TRUE;
-			phdr.channel = tvb_get_guint8(tvb, offset + 6);
-			if (tree) {
-				static const int * xchannel_flags[] = {
-					&hf_radiotap_xchannel_flags_turbo,
-					&hf_radiotap_xchannel_flags_cck,
-					&hf_radiotap_xchannel_flags_ofdm,
-					&hf_radiotap_xchannel_flags_2ghz,
-					&hf_radiotap_xchannel_flags_5ghz,
-					&hf_radiotap_xchannel_flags_passive,
-					&hf_radiotap_xchannel_flags_dynamic,
-					&hf_radiotap_xchannel_flags_gfsk,
-					&hf_radiotap_xchannel_flags_gsm,
-					&hf_radiotap_xchannel_flags_sturbo,
-					&hf_radiotap_xchannel_flags_half,
-					&hf_radiotap_xchannel_flags_quarter,
-					&hf_radiotap_xchannel_flags_ht20,
-					&hf_radiotap_xchannel_flags_ht40u,
-					&hf_radiotap_xchannel_flags_ht40d,
-					NULL
-				};
-
-				proto_tree_add_item(radiotap_tree,
-							hf_radiotap_xchannel_channel,
-							tvb, offset + 6, 1,
-							ENC_LITTLE_ENDIAN);
-				proto_tree_add_item(radiotap_tree,
-							hf_radiotap_xchannel_frequency,
-							tvb, offset + 4, 2, ENC_LITTLE_ENDIAN);
-
-				proto_tree_add_bitmask(radiotap_tree, tvb, offset, hf_radiotap_xchannel_flags, ett_radiotap_xchannel_flags, xchannel_flags, ENC_LITTLE_ENDIAN);
-
-
-#if 0
-				proto_tree_add_uint(radiotap_tree,
-							hf_radiotap_xchannel_maxpower,
-							tvb, offset + 7, 1, maxpower);
-#endif
-			}
+		case IEEE80211_RADIOTAP_XCHANNEL:
+			dissect_radiotap_xchannel(tvb, pinfo, radiotap_tree,
+						offset, rflags, have_rflags,
+						radiotap_info, &phdr);
 			break;
-		}
+
 		case IEEE80211_RADIOTAP_MCS: {
 			proto_tree *mcs_tree = NULL;
 			guint8	    mcs_known, mcs_flags;
@@ -2303,29 +2390,8 @@ dissect_radiotap(tvbuff_t * tvb, packet_info * pinfo, proto_tree * tree, void* u
 			break;
 		}
 		case IEEE80211_RADIOTAP_TIMESTAMP: {
-			proto_item *it_root;
-			proto_tree *ts_tree, *flg_tree;
-
-			it_root = proto_tree_add_item(radiotap_tree, hf_radiotap_timestamp,
-					tvb, offset, 12, ENC_NA);
-			ts_tree = proto_item_add_subtree(it_root, ett_radiotap_timestamp);
-
-			proto_tree_add_item(ts_tree, hf_radiotap_timestamp_ts,
-					tvb, offset, 8, ENC_LITTLE_ENDIAN);
-			if (tvb_get_letohs(tvb, offset + 11) & IEEE80211_RADIOTAP_TS_FLG_ACCURACY)
-				proto_tree_add_item(ts_tree, hf_radiotap_timestamp_accuracy,
-					tvb, offset + 8, 2, ENC_LITTLE_ENDIAN);
-			proto_tree_add_item(ts_tree, hf_radiotap_timestamp_unit,
-					tvb, offset + 10, 1, ENC_LITTLE_ENDIAN);
-			proto_tree_add_item(ts_tree, hf_radiotap_timestamp_spos,
-					tvb, offset + 10, 1, ENC_LITTLE_ENDIAN);
-			flg_tree = proto_item_add_subtree(ts_tree, ett_radiotap_timestamp_flags);
-			proto_tree_add_item(flg_tree,
-					hf_radiotap_timestamp_flags_32bit, tvb,
-					offset + 11, 1, ENC_LITTLE_ENDIAN);
-			proto_tree_add_item(flg_tree,
-					hf_radiotap_timestamp_flags_accuracy, tvb,
-					offset + 11, 1, ENC_LITTLE_ENDIAN);
+			dissect_radiotap_timestamp(tvb, pinfo, radiotap_tree,
+					offset, radiotap_info, &phdr);
 			break;
 		}
 		case IEEE80211_RADIOTAP_HE: