[FINAL] timestamp field

[FINAL] timestamp field

[Johannes Berg]

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Since there was no objection, reposting as final - will adopt in a week
from now unless there are any final objections.

The definition can be found at
http://www.radiotap.org/suggested-fields/timestamp

johannes

[-- Attachment #2: wireshark-radiotap-timstamp.patch --]
[-- Type: text/x-patch, Size: 9542 bytes --]

diff --git a/epan/dissectors/packet-ieee80211-radiotap-defs.h b/epan/dissectors/packet-ieee80211-radiotap-defs.h
index 25dd231bd7b9..6ea0ff23af14 100644
--- a/epan/dissectors/packet-ieee80211-radiotap-defs.h
+++ b/epan/dissectors/packet-ieee80211-radiotap-defs.h
@@ -207,6 +207,7 @@ enum ieee80211_radiotap_type {
 	IEEE80211_RADIOTAP_MCS = 19,
 	IEEE80211_RADIOTAP_AMPDU_STATUS = 20,
 	IEEE80211_RADIOTAP_VHT = 21,
+	IEEE80211_RADIOTAP_TIMESTAMP = 22,
 
 	/* valid in every it_present bitmap, even vendor namespaces */
 	IEEE80211_RADIOTAP_RADIOTAP_NAMESPACE = 29,
@@ -215,8 +216,8 @@ enum ieee80211_radiotap_type {
 };
 
 /* not (yet) defined Radiotap present flag */
-/* Bit 22 to 28 are not defined (in binary : 0001 1111 1100 0000 0000 0000 0000 0000 */
-#define IEEE80211_RADIOTAP_NOTDEFINED 0x1FC00000
+/* Bit 23 to 28 are not defined (in binary : 0001 1111 1000 0000 0000 0000 0000 0000 */
+#define IEEE80211_RADIOTAP_NOTDEFINED 0x1F800000
 
 /* Channel flags. */
 /* 0x00000001 through 0x00000008 undefined (reserved?) */
@@ -362,5 +363,19 @@ enum ieee80211_radiotap_type {
 #define IEEE80211_RADIOTAP_VHT_BW_20UUL		24
 #define IEEE80211_RADIOTAP_VHT_BW_20UUU		25
 
+/* for IEEE80211_RADIOTAP_TIMESTAMP */
+#define IEEE80211_RADIOTAP_TS_UNIT_MASK		0x0F
+#define IEEE80211_RADIOTAP_TS_UNIT_MSEC		0x00
+#define IEEE80211_RADIOTAP_TS_UNIT_USEC		0x01
+#define IEEE80211_RADIOTAP_TS_UNIT_NSEC		0x02
+#define IEEE80211_RADIOTAP_TS_SPOS_MASK		0xF0
+#define IEEE80211_RADIOTAP_TS_SPOS_SHIFT	4
+#define IEEE80211_RADIOTAP_TS_SPOS_MPDU		0x0
+#define IEEE80211_RADIOTAP_TS_SPOS_ACQ		0x1
+#define IEEE80211_RADIOTAP_TS_SPOS_EOF		0x2
+#define IEEE80211_RADIOTAP_TS_SPOS_UNDEF	0xF
+
+#define IEEE80211_RADIOTAP_TS_FLG_32BIT		0x01
+#define IEEE80211_RADIOTAP_TS_FLG_ACCURACY	0x02
 
 #endif				/* IEEE80211_RADIOTAP_H */
diff --git a/epan/dissectors/packet-ieee80211-radiotap-iter.c b/epan/dissectors/packet-ieee80211-radiotap-iter.c
index 799a78ecdc2d..1d1053d3dd8d 100644
--- a/epan/dissectors/packet-ieee80211-radiotap-iter.c
+++ b/epan/dissectors/packet-ieee80211-radiotap-iter.c
@@ -62,7 +62,8 @@ static const struct radiotap_align_size rtap_namespace_sizes[] = {
 	/* [IEEE80211_RADIOTAP_XCHANNEL] = 18 */		{ 0, 0 }, /* Unofficial, used by FreeBSD */
 	/* [IEEE80211_RADIOTAP_MCS] = 19 */			{ 1, 3 },
 	/* [IEEE80211_RADIOTAP_AMPDU_STATUS] = 20 */		{ 4, 8 },
-	/* [IEEE80211_RADIOTAP_VHT] = 21 */			{ 2, 12 }
+	/* [IEEE80211_RADIOTAP_VHT] = 21 */			{ 2, 12 },
+	/* [IEEE80211_RADIOTAP_TIMESTAMP] = 22 */		{ 8, 12 }
 
 	/*
 	 * add more here as they are defined in
diff --git a/epan/dissectors/packet-ieee80211-radiotap.c b/epan/dissectors/packet-ieee80211-radiotap.c
index 205b26427af9..728a9d5717cb 100644
--- a/epan/dissectors/packet-ieee80211-radiotap.c
+++ b/epan/dissectors/packet-ieee80211-radiotap.c
@@ -154,6 +154,14 @@ static int hf_radiotap_vht_datarate[4] = { -1, -1, -1, -1 };
 static int hf_radiotap_vht_gid = -1;
 static int hf_radiotap_vht_p_aid = -1;
 static int hf_radiotap_vht_user = -1;
+static int hf_radiotap_timestamp = -1;
+static int hf_radiotap_timestamp_ts = -1;
+static int hf_radiotap_timestamp_accuracy = -1;
+static int hf_radiotap_timestamp_unit = -1;
+static int hf_radiotap_timestamp_spos = -1;
+static int hf_radiotap_timestamp_flags = -1;
+static int hf_radiotap_timestamp_flags_32bit = -1;
+static int hf_radiotap_timestamp_flags_accuracy = -1;
 
 /* "Present" flags */
 static int hf_radiotap_present_tsft = -1;
@@ -176,6 +184,7 @@ static int hf_radiotap_present_xchannel = -1;
 static int hf_radiotap_present_mcs = -1;
 static int hf_radiotap_present_ampdu = -1;
 static int hf_radiotap_present_vht = -1;
+static int hf_radiotap_present_timestamp = -1;
 static int hf_radiotap_present_reserved = -1;
 static int hf_radiotap_present_rtap_ns = -1;
 static int hf_radiotap_present_vendor_ns = -1;
@@ -210,6 +219,8 @@ static gint ett_radiotap_ampdu_flags = -1;
 static gint ett_radiotap_vht = -1;
 static gint ett_radiotap_vht_known = -1;
 static gint ett_radiotap_vht_user = -1;
+static gint ett_radiotap_timestamp = -1;
+static gint ett_radiotap_timestamp_flags = -1;
 
 static expert_field ei_radiotap_data_past_header = EI_INIT;
 static expert_field ei_radiotap_present_reserved = EI_INIT;
@@ -430,6 +441,23 @@ static const true_false_string preamble_type = {
 	"Long",
 };
 
+static const value_string timestamp_unit[] = {
+	{ IEEE80211_RADIOTAP_TS_UNIT_MSEC, "msec" },
+	{ IEEE80211_RADIOTAP_TS_UNIT_USEC, "usec" },
+	{ IEEE80211_RADIOTAP_TS_UNIT_NSEC, "nsec" },
+	{ 0, NULL }
+};
+static value_string_ext timestamp_unit_ext = VALUE_STRING_EXT_INIT(timestamp_unit);
+
+static const value_string timestamp_spos[] = {
+	{ IEEE80211_RADIOTAP_TS_SPOS_MPDU, "first MPDU bit/symbol" },
+	{ IEEE80211_RADIOTAP_TS_SPOS_ACQ, "signal acquisition" },
+	{ IEEE80211_RADIOTAP_TS_SPOS_EOF, "end of frame" },
+	{ IEEE80211_RADIOTAP_TS_SPOS_UNDEF, "undefined" },
+	{ 0, NULL }
+};
+static value_string_ext timestamp_spos_ext = VALUE_STRING_EXT_INIT(timestamp_spos);
+
 /*
  * The NetBSD ieee80211_radiotap man page
  * (http://netbsd.gw.com/cgi-bin/man-cgi?ieee80211_radiotap+9+NetBSD-current)
@@ -744,6 +772,9 @@ dissect_radiotap(tvbuff_t * tvb, packet_info * pinfo, proto_tree * tree, void* u
 			proto_tree_add_item(present_tree,
 					    hf_radiotap_present_vht, tvb,
 					    offset + 4, 4, ENC_LITTLE_ENDIAN);
+			proto_tree_add_item(present_tree,
+					    hf_radiotap_present_timestamp, tvb,
+					    offset + 4, 4, ENC_LITTLE_ENDIAN);
 			ti = proto_tree_add_item(present_tree,
 					    hf_radiotap_present_reserved, tvb,
 					    offset + 4, 4, ENC_LITTLE_ENDIAN);
@@ -1739,6 +1770,32 @@ dissect_radiotap(tvbuff_t * tvb, packet_info * pinfo, proto_tree * tree, void* u
 
 			break;
 		}
+		case IEEE80211_RADIOTAP_TIMESTAMP:
+			if (tree) {
+				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);
+			}
 		}
 	}
 
@@ -1927,6 +1984,11 @@ void proto_register_radiotap(void)
 		  FT_BOOLEAN, 32, TFS(&tfs_present_absent), RADIOTAP_MASK(VHT),
 		  "Specifies if the VHT field is present", HFILL}},
 
+		{&hf_radiotap_present_timestamp,
+		 {"frame timestamp", "radiotap.present.timestamp",
+		  FT_BOOLEAN, 32, TFS(&tfs_present_absent), RADIOTAP_MASK(TIMESTAMP),
+		  "Specifies if the timestamp field is present", HFILL}},
+
 		{&hf_radiotap_present_reserved,
 		 {"Reserved", "radiotap.present.reserved",
 		  FT_UINT32, BASE_HEX, NULL, IEEE80211_RADIOTAP_NOTDEFINED,
@@ -2586,6 +2648,48 @@ void proto_register_radiotap(void)
 		  FT_UINT16, BASE_DEC, NULL, 0x0,
 		  NULL, HFILL}},
 
+		{&hf_radiotap_timestamp,
+		 {"timestamp information", "radiotap.timestamp",
+		  FT_NONE, BASE_NONE, NULL, 0x0,
+		  NULL, HFILL}},
+
+		{&hf_radiotap_timestamp_ts,
+		 {"timestamp", "radiotap.timestamp.ts",
+		  FT_UINT64, BASE_DEC, NULL, 0x0,
+		  NULL, HFILL}},
+
+		{&hf_radiotap_timestamp_accuracy,
+		 {"accuracy", "radiotap.timestamp.accuracy",
+		  FT_UINT16, BASE_DEC, NULL, 0x0,
+		  NULL, HFILL}},
+
+		{&hf_radiotap_timestamp_unit,
+		 {"unit", "radiotap.timestamp.unit",
+		  FT_UINT8, BASE_DEC | BASE_EXT_STRING, &timestamp_unit_ext,
+		  IEEE80211_RADIOTAP_TS_UNIT_MASK,
+		  NULL, HFILL}},
+
+		{&hf_radiotap_timestamp_spos,
+		 {"sampling position", "radiotap.timestamp.samplingpos",
+		  FT_UINT8, BASE_DEC | BASE_EXT_STRING, &timestamp_spos_ext,
+		  IEEE80211_RADIOTAP_TS_SPOS_MASK,
+		  NULL, HFILL}},
+
+		{&hf_radiotap_timestamp_flags,
+		 {"timestamp flags", "radiotap.timestamp.flags",
+		  FT_NONE, BASE_NONE, NULL, 0x0,
+		  NULL, HFILL}},
+
+		{&hf_radiotap_timestamp_flags_32bit,
+		 {"32-bit counter", "radiotap.timestamp.flags.32bit",
+		  FT_BOOLEAN, 8, TFS(&tfs_yes_no), IEEE80211_RADIOTAP_TS_FLG_32BIT,
+		  NULL, HFILL}},
+
+		{&hf_radiotap_timestamp_flags_accuracy,
+		 {"accuracy field", "radiotap.timestamp.flags.accuracy",
+		  FT_BOOLEAN, 8, TFS(&tfs_present_absent), IEEE80211_RADIOTAP_TS_FLG_ACCURACY,
+		  NULL, HFILL}},
+
 		{&hf_radiotap_vendor_ns,
 		 {"Vendor namespace", "radiotap.vendor_namespace",
 		  FT_BYTES, BASE_NONE, NULL, 0x0,
@@ -2632,7 +2736,9 @@ void proto_register_radiotap(void)
 		&ett_radiotap_ampdu_flags,
 		&ett_radiotap_vht,
 		&ett_radiotap_vht_known,
-		&ett_radiotap_vht_user
+		&ett_radiotap_vht_user,
+		&ett_radiotap_timestamp,
+		&ett_radiotap_timestamp_flags,
 	};
 	static ei_register_info ei[] = {
 		{ &ei_radiotap_present, { "radiotap.present.radiotap_and_vendor", PI_MALFORMED, PI_ERROR, "Both radiotap and vendor namespace specified in bitmask word", EXPFILL }},

[-- Attachment #3: hwsim-radiotap-timestamp.patch --]
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diff --git a/drivers/net/wireless/mac80211_hwsim.c b/drivers/net/wireless/mac80211_hwsim.c
index c32889a1e39c..6b1082797861 100644
--- a/drivers/net/wireless/mac80211_hwsim.c
+++ b/drivers/net/wireless/mac80211_hwsim.c
@@ -551,6 +551,13 @@ struct hwsim_radiotap_hdr {
 	u8 rt_rate;
 	__le16 rt_channel;
 	__le16 rt_chbitmask;
+	__le16 reserved;
+	struct {
+		__le64 ts;
+		__le16 accuracy;
+		u8 unit_pos;
+		u8 flags;
+	} ts;
 } __packed;
 
 struct hwsim_radiotap_ack_hdr {
@@ -831,6 +838,7 @@ static void mac80211_hwsim_monitor_rx(struct ieee80211_hw *hw,
 	hdr->hdr.it_present = cpu_to_le32((1 << IEEE80211_RADIOTAP_FLAGS) |
 					  (1 << IEEE80211_RADIOTAP_RATE) |
 					  (1 << IEEE80211_RADIOTAP_TSFT) |
+					  BIT(22) |
 					  (1 << IEEE80211_RADIOTAP_CHANNEL));
 	hdr->rt_tsft = __mac80211_hwsim_get_tsf(data);
 	hdr->rt_flags = 0;
@@ -842,6 +850,10 @@ static void mac80211_hwsim_monitor_rx(struct ieee80211_hw *hw,
 	else
 		flags |= IEEE80211_CHAN_CCK;
 	hdr->rt_chbitmask = cpu_to_le16(flags);
+	hdr->ts.ts = cpu_to_le64(ktime_get_boot_ns());
+	hdr->ts.accuracy = 0;
+	hdr->ts.unit_pos = 0x22;
+	hdr->ts.flags = 0x02;
 
 	skb->dev = hwsim_mon;
 	skb_set_mac_header(skb, 0);

Re: [FINAL] timestamp field

[Guy Harris]

On Aug 4, 2016, at 10:48 PM, Johannes Berg <johannes-cdvu00un1VgdHxzADdlk8Q@public.gmane.org> wrote:

> Since there was no objection, reposting as final - will adopt in a week
> from now unless there are any final objections.
> 
> The definition can be found at
> http://www.radiotap.org/suggested-fields/timestamp

Does the fact that the Wireshark patch doesn't involve an FT_ABSOLUTE_TIME field mean that the time stamps aren't relative to some fixed time such as the UNIX epoch, so that they can be used to calculate the time between two events but not the wall-clock time of a single event?

Re: [FINAL] timestamp field

[Johannes Berg]

On Fri, 2016-08-05 at 03:46 -0700, Guy Harris wrote:
> On Aug 4, 2016, at 10:48 PM, Johannes Berg <johannes-cdvu00un1VgdHxzADdlk8Q@public.gmane.org
> > wrote:
> 
> > Since there was no objection, reposting as final - will adopt in a
> > week
> > from now unless there are any final objections.
> > 
> > The definition can be found at
> > http://www.radiotap.org/suggested-fields/timestamp
> 
> Does the fact that the Wireshark patch doesn't involve an
> FT_ABSOLUTE_TIME field mean that the time stamps aren't relative to
> some fixed time such as the UNIX epoch, so that they can be used to
> calculate the time between two events but not the wall-clock time of
> a single event?

I don't see a way to make them absolute, but it's something we could
consider adding perhaps? Maybe eventually wifi hardware will have some
clock sync with something.

Right now my main use-case is going to be exporting the timestamp from
the hardware, which isn't like the existing MACTIME, and then using
that to synchronize two or more captures (by finding common frames,
like beacons).

I must admit I hadn't thought about absolute times in the context of
radiotap at all.

johannes

[ADOPTED] timestamp field

[Johannes Berg]

> http://www.radiotap.org/defined-fields/timestamp

I look at the absolute timestamp, but we can't really do that right now
since we don't have hardware sync. If anyone wants to do it in some
way, please come up with an extension (to this field, or new, or
whatever is needed)

johannes