2 * Routines for GSMTAP captures
4 * (C) 2008-2010 by Harald Welte <laforge@gnumonks.org>
8 * Wireshark - Network traffic analyzer
9 * By Gerald Combs <gerald@wireshark.org>
10 * Copyright 1998 Gerald Combs
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation; either version 2
15 * of the License, or (at your option) any later version.
17 * This program is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU General Public License for more details.
22 * You should have received a copy of the GNU General Public License
23 * along with this program; if not, write to the Free Software
24 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
29 /* GSMTAP is a generic header format for GSM protocol captures,
30 * it uses the IANA-assigned UDP port number 4729 and carries
31 * payload in various formats of GSM interfaces such as Um MAC
32 * blocks or Um bursts.
34 * Example programs generating GSMTAP data are airprobe
35 * (http://airprobe.org/) or OsmocomBB (http://bb.osmocom.org/)
43 #include <epan/packet.h>
44 #include <epan/prefs.h>
46 #define GSMTAP_TYPE_UM 0x01
47 #define GSMTAP_TYPE_ABIS 0x02
48 #define GSMTAP_TYPE_UM_BURST 0x03 /* raw burst bits */
50 #define GSMTAP_BURST_UNKNOWN 0x00
51 #define GSMTAP_BURST_FCCH 0x01
52 #define GSMTAP_BURST_PARTIAL_SCH 0x02
53 #define GSMTAP_BURST_SCH 0x03
54 #define GSMTAP_BURST_CTS_SCH 0x04
55 #define GSMTAP_BURST_COMPACT_SCH 0x05
56 #define GSMTAP_BURST_NORMAL 0x06
57 #define GSMTAP_BURST_DUMMY 0x07
58 #define GSMTAP_BURST_ACCESS 0x08
59 #define GSMTAP_BURST_NONE 0x09
61 #define GSMTAP_CHANNEL_UNKNOWN 0x00
62 #define GSMTAP_CHANNEL_BCCH 0x01
63 #define GSMTAP_CHANNEL_CCCH 0x02
64 #define GSMTAP_CHANNEL_RACH 0x03
65 #define GSMTAP_CHANNEL_AGCH 0x04
66 #define GSMTAP_CHANNEL_PCH 0x05
67 #define GSMTAP_CHANNEL_SDCCH 0x06
68 #define GSMTAP_CHANNEL_SDCCH4 0x07
69 #define GSMTAP_CHANNEL_SDCCH8 0x08
70 #define GSMTAP_CHANNEL_TCH_F 0x09
71 #define GSMTAP_CHANNEL_TCH_H 0x0a
72 #define GSMTAP_CHANNEL_ACCH 0x80
74 #define GSMTAP_ARFCN_F_PCS 0x8000
75 #define GSMTAP_ARFCN_F_UPLINK 0x4000
76 #define GSMTAP_ARFCN_MASK 0x3fff
78 #define GSMTAP_UDP_PORT 4729
80 /* This is the header as it is used by gsmtap-generating software.
81 * It is not used by the wireshark dissector and provided for reference only.
83 guint8 version; // version, set to 0x01 currently
84 guint8 hdr_len; // length in number of 32bit words
85 guint8 type; // see GSMTAP_TYPE_*
86 guint8 timeslot; // timeslot (0..7 on Um)
88 guint16 arfcn; // ARFCN (frequency)
89 gint8 signal_dbm; // signal level in dBm
90 gint8 snr_db; // signal/noise ratio in dB
92 guint32 frame_number; // GSM Frame Number (FN)
94 guint8 sub_type; // Type of burst/channel, see above
95 guint8 antenna_nr; // Antenna Number
96 guint8 sub_slot; // sub-slot within timeslot
97 guint8 res; // reserved for future use (RFU)
101 static int proto_gsmtap = -1;
103 static int hf_gsmtap_version = -1;
104 static int hf_gsmtap_hdrlen = -1;
105 static int hf_gsmtap_type = -1;
106 static int hf_gsmtap_timeslot = -1;
107 static int hf_gsmtap_subslot = -1;
108 static int hf_gsmtap_arfcn = -1;
109 static int hf_gsmtap_uplink = -1;
110 static int hf_gsmtap_noise_dbm = -1;
111 static int hf_gsmtap_signal_dbm = -1;
112 static int hf_gsmtap_frame_nr = -1;
113 static int hf_gsmtap_burst_type = -1;
114 static int hf_gsmtap_channel_type = -1;
115 static int hf_gsmtap_antenna = -1;
117 static int hf_sacch_l1h_power_lev = -1;
118 static int hf_sacch_l1h_fpc = -1;
119 static int hf_sacch_l1h_ta = -1;
121 static gint ett_gsmtap = -1;
132 static dissector_handle_t sub_handles[GSMTAP_SUB_MAX];
134 static const value_string gsmtap_bursts[] = {
135 { GSMTAP_BURST_UNKNOWN, "UNKNOWN" },
136 { GSMTAP_BURST_FCCH, "FCCH" },
137 { GSMTAP_BURST_PARTIAL_SCH, "PARTIAL SCH" },
138 { GSMTAP_BURST_SCH, "SCH" },
139 { GSMTAP_BURST_CTS_SCH, "CTS SCH" },
140 { GSMTAP_BURST_COMPACT_SCH, "COMPACT SCH" },
141 { GSMTAP_BURST_NORMAL, "NORMAL" },
142 { GSMTAP_BURST_DUMMY, "DUMMY" },
143 { GSMTAP_BURST_ACCESS, "RACH" },
147 static const value_string gsmtap_channels[] = {
148 { GSMTAP_CHANNEL_UNKNOWN, "UNKNOWN" },
149 { GSMTAP_CHANNEL_BCCH, "BCCH" },
150 { GSMTAP_CHANNEL_CCCH, "CCCH" },
151 { GSMTAP_CHANNEL_RACH, "RACH" },
152 { GSMTAP_CHANNEL_AGCH, "AGCH" },
153 { GSMTAP_CHANNEL_PCH, "PCH" },
154 { GSMTAP_CHANNEL_SDCCH, "SDCCH" },
155 { GSMTAP_CHANNEL_SDCCH4, "SDCCH/4" },
156 { GSMTAP_CHANNEL_SDCCH8, "SDCCH/8" },
157 { GSMTAP_CHANNEL_TCH_F, "FACCH/F" },
158 { GSMTAP_CHANNEL_TCH_H, "FACCH/H" },
159 { GSMTAP_CHANNEL_ACCH|
160 GSMTAP_CHANNEL_SDCCH, "LSACCH" },
161 { GSMTAP_CHANNEL_ACCH|
162 GSMTAP_CHANNEL_SDCCH4, "SACCH/4" },
163 { GSMTAP_CHANNEL_ACCH|
164 GSMTAP_CHANNEL_SDCCH8, "SACCH/8" },
165 { GSMTAP_CHANNEL_ACCH|
166 GSMTAP_CHANNEL_TCH_F, "SACCH/F" },
167 { GSMTAP_CHANNEL_ACCH|
168 GSMTAP_CHANNEL_TCH_F, "SACCH/H" },
172 static const value_string gsmtap_types[] = {
173 { GSMTAP_TYPE_UM, "GSM Um (MS<->BTS)" },
174 { GSMTAP_TYPE_ABIS, "GSM Abis (BTS<->BSC)" },
175 { GSMTAP_TYPE_UM_BURST, "GSM Um burst (MS<->BTS)" },
179 /* dissect a SACCH L1 header which is included in the first 2 bytes
180 * of every SACCH frame (according to TS 04.04) */
182 dissect_sacch_l1h(tvbuff_t *tvb, proto_tree *tree)
185 proto_tree *l1h_tree = NULL;
190 ti = proto_tree_add_protocol_format(tree, proto_gsmtap, tvb, 0, 2,
191 "SACCH L1 Header, Power Level: %u, Timing Advance: %u",
192 tvb_get_guint8(tvb, 0) & 0x1f,
193 tvb_get_guint8(tvb, 1));
194 l1h_tree = proto_item_add_subtree(ti, ett_gsmtap);
196 proto_tree_add_item(l1h_tree, hf_sacch_l1h_power_lev, tvb, 0, 1, FALSE);
197 /* Fast Power Control */
198 proto_tree_add_item(l1h_tree, hf_sacch_l1h_fpc, tvb, 0, 1, FALSE);
199 /* Acutal Timing Advance */
200 proto_tree_add_item(l1h_tree, hf_sacch_l1h_ta, tvb, 1, 1, FALSE);
203 /* dissect a GSMTAP header and hand payload off to respective dissector */
205 dissect_gsmtap(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
207 int sub_handle, len, offset = 0;
209 proto_tree *gsmtap_tree = NULL;
210 tvbuff_t *payload_tvb, *l1h_tvb = NULL;
211 guint8 hdr_len, type, sub_type;
214 len = tvb_length(tvb);
216 hdr_len = tvb_get_guint8(tvb, offset + 1) <<2;
217 type = tvb_get_guint8(tvb, offset + 2);
218 sub_type = tvb_get_guint8(tvb, offset + 12);
219 arfcn = tvb_get_ntohs(tvb, offset + 4);
221 /* In case of a SACCH, there is a two-byte L1 header in front
222 * of the packet (see TS 04.04) */
223 if (type == GSMTAP_TYPE_UM &&
224 sub_type & GSMTAP_CHANNEL_ACCH) {
225 l1h_tvb = tvb_new_subset(tvb, hdr_len, 2, 2);
226 payload_tvb = tvb_new_subset(tvb, hdr_len+2, len-(hdr_len+2),
229 payload_tvb = tvb_new_subset(tvb, hdr_len, len-hdr_len,
233 /* We don't want any UDP related info left in the INFO field, as the
234 * gsm_a_dtap dissector will not clear but only append */
235 col_clear(pinfo->cinfo, COL_INFO);
237 col_set_str(pinfo->cinfo, COL_PROTOCOL, "GSMTAP");
239 if (arfcn & GSMTAP_ARFCN_F_UPLINK) {
240 col_append_str(pinfo->cinfo, COL_RES_NET_SRC, "MS");
241 col_append_str(pinfo->cinfo, COL_RES_NET_DST, "BTS");
242 /* p2p_dir is used by the LAPDm dissector */
243 pinfo->p2p_dir = P2P_DIR_SENT;
245 col_set_str(pinfo->cinfo, COL_RES_NET_SRC, "BTS");
246 switch (sub_type & ~GSMTAP_CHANNEL_ACCH) {
247 case GSMTAP_CHANNEL_BCCH:
248 case GSMTAP_CHANNEL_CCCH:
249 case GSMTAP_CHANNEL_PCH:
250 case GSMTAP_CHANNEL_AGCH:
251 col_set_str(pinfo->cinfo, COL_RES_NET_DST, "Broadcast");
254 col_set_str(pinfo->cinfo, COL_RES_NET_DST, "MS");
257 /* p2p_dir is used by the LAPDm dissector */
258 pinfo->p2p_dir = P2P_DIR_RECV;
262 ti = proto_tree_add_protocol_format(tree, proto_gsmtap, tvb, 0, hdr_len,
263 "GSM TAP Header, ARFCN: %u (%s), TS: %u, Channel: %s (%u)",
264 arfcn & GSMTAP_ARFCN_MASK,
265 arfcn & GSMTAP_ARFCN_F_UPLINK ? "Uplink" : "Downlink",
266 tvb_get_guint8(tvb, offset+3),
267 val_to_str(tvb_get_guint8(tvb, offset+12), gsmtap_channels, "Unknown: %d"),
268 tvb_get_guint8(tvb, offset+14));
269 gsmtap_tree = proto_item_add_subtree(ti, ett_gsmtap);
270 proto_tree_add_item(gsmtap_tree, hf_gsmtap_version,
271 tvb, offset, 1, FALSE);
272 proto_tree_add_uint_format(gsmtap_tree, hf_gsmtap_hdrlen,
273 tvb, offset+1, 1, hdr_len,
274 "Header length: %u bytes", hdr_len);
275 proto_tree_add_item(gsmtap_tree, hf_gsmtap_type,
276 tvb, offset+2, 1, FALSE);
277 proto_tree_add_item(gsmtap_tree, hf_gsmtap_timeslot,
278 tvb, offset+3, 1, FALSE);
279 proto_tree_add_item(gsmtap_tree, hf_gsmtap_arfcn,
280 tvb, offset+4, 2, FALSE);
281 proto_tree_add_item(gsmtap_tree, hf_gsmtap_uplink,
282 tvb, offset+4, 2, FALSE);
283 proto_tree_add_item(gsmtap_tree, hf_gsmtap_noise_dbm,
284 tvb, offset+6, 1, FALSE);
285 proto_tree_add_item(gsmtap_tree, hf_gsmtap_signal_dbm,
286 tvb, offset+7, 1, FALSE);
287 proto_tree_add_item(gsmtap_tree, hf_gsmtap_frame_nr,
288 tvb, offset+8, 4, FALSE);
289 if (type == GSMTAP_TYPE_UM_BURST)
290 proto_tree_add_item(gsmtap_tree, hf_gsmtap_burst_type,
291 tvb, offset+12, 1, FALSE);
292 else if (type == GSMTAP_TYPE_UM)
293 proto_tree_add_item(gsmtap_tree, hf_gsmtap_channel_type,
294 tvb, offset+12, 1, FALSE);
295 proto_tree_add_item(gsmtap_tree, hf_gsmtap_antenna,
296 tvb, offset+13, 1, FALSE);
297 proto_tree_add_item(gsmtap_tree, hf_gsmtap_subslot,
298 tvb, offset+14, 1, FALSE);
304 dissect_sacch_l1h(l1h_tvb, tree);
305 switch (sub_type & ~GSMTAP_CHANNEL_ACCH) {
306 case GSMTAP_CHANNEL_BCCH:
307 case GSMTAP_CHANNEL_CCCH:
308 case GSMTAP_CHANNEL_PCH:
309 case GSMTAP_CHANNEL_AGCH:
310 /* FIXME: we might want to skip idle frames */
311 sub_handle = GSMTAP_SUB_UM;
313 case GSMTAP_CHANNEL_SDCCH:
314 case GSMTAP_CHANNEL_SDCCH4:
315 case GSMTAP_CHANNEL_SDCCH8:
316 case GSMTAP_CHANNEL_TCH_F:
317 case GSMTAP_CHANNEL_TCH_H:
318 sub_handle = GSMTAP_SUB_UM_LAPDM;
320 case GSMTAP_CHANNEL_RACH:
322 sub_handle = GSMTAP_SUB_DATA;
326 case GSMTAP_TYPE_UM_BURST:
328 sub_handle = GSMTAP_SUB_DATA;
331 call_dissector(sub_handles[sub_handle], payload_tvb, pinfo, tree);
334 static const true_false_string sacch_l1h_fpc_mode_vals = {
340 proto_register_gsmtap(void)
342 static hf_register_info hf[] = {
343 { &hf_gsmtap_version, { "Version", "gsmtap.version",
344 FT_UINT8, BASE_DEC, NULL, 0, NULL, HFILL } },
345 { &hf_gsmtap_hdrlen, { "Header Length", "gsmtap.hdr_len",
346 FT_UINT8, BASE_DEC, NULL, 0, NULL, HFILL } },
347 { &hf_gsmtap_type, { "Payload Type", "gsmtap.type",
348 FT_UINT8, BASE_DEC, VALS(gsmtap_types), 0, NULL, HFILL } },
349 { &hf_gsmtap_timeslot, { "Time Slot", "gsmtap.ts",
350 FT_UINT8, BASE_DEC, NULL, 0, NULL, HFILL } },
351 { &hf_gsmtap_arfcn, { "ARFCN", "gsmtap.arfcn",
352 FT_UINT16, BASE_DEC, NULL, GSMTAP_ARFCN_MASK, NULL, HFILL } },
353 { &hf_gsmtap_uplink, { "Uplink", "gsmtap.uplink",
354 FT_UINT16, BASE_DEC, NULL, GSMTAP_ARFCN_F_UPLINK, NULL, HFILL } },
355 { &hf_gsmtap_noise_dbm, { "Signal/Noise Ratio (dB)", "gsmtap.snr_db",
356 FT_UINT8, BASE_DEC, NULL, 0, NULL, HFILL } },
357 { &hf_gsmtap_signal_dbm, { "Signal Level (dBm)", "gsmtap.signal_dbm",
358 FT_UINT8, BASE_DEC, NULL, 0, NULL, HFILL } },
359 { &hf_gsmtap_frame_nr, { "GSM Frame Number", "gsmtap.frame_nr",
360 FT_UINT32, BASE_DEC, NULL, 0, NULL, HFILL } },
361 { &hf_gsmtap_burst_type, { "Burst Type", "gsmtap.burst_type",
362 FT_UINT8, BASE_DEC, VALS(gsmtap_bursts), 0, NULL, HFILL }},
363 { &hf_gsmtap_channel_type, { "Channel Type", "gsmtap.chan_type",
364 FT_UINT8, BASE_DEC, VALS(gsmtap_channels), 0, NULL, HFILL }},
365 { &hf_gsmtap_antenna, { "Antenna Number", "gsmtap.antenna",
366 FT_UINT8, BASE_DEC, NULL, 0, NULL, HFILL } },
367 { &hf_gsmtap_subslot, { "Sub-Slot", "gsmtap.sub_slot",
368 FT_UINT8, BASE_DEC, NULL, 0, NULL, HFILL } },
370 { &hf_sacch_l1h_power_lev, { "MS power level", "gsmtap.sacch_l1.power_lev",
371 FT_UINT8, BASE_DEC, NULL, 0x1f, NULL, HFILL } },
372 { &hf_sacch_l1h_fpc, { "FPC", "gsmtap.sacch_l1.fpc",
373 FT_BOOLEAN, 8, TFS(&sacch_l1h_fpc_mode_vals), 0x04,
375 { &hf_sacch_l1h_ta, { "Actual Timing Advance", "gsmtap.sacch_l1.ta",
376 FT_UINT8, BASE_DEC, NULL, 0, NULL, HFILL } },
378 static gint *ett[] = {
382 proto_gsmtap = proto_register_protocol("GSM Radiotap", "GSMTAP", "gsmtap");
383 proto_register_field_array(proto_gsmtap, hf, array_length(hf));
384 proto_register_subtree_array(ett, array_length(ett));
388 proto_reg_handoff_gsmtap(void)
390 dissector_handle_t gsmtap_handle;
392 sub_handles[GSMTAP_SUB_DATA] = find_dissector("data");
393 sub_handles[GSMTAP_SUB_UM] = find_dissector("gsm_a_ccch");
394 sub_handles[GSMTAP_SUB_UM_LAPDM] = find_dissector("lapdm");
395 sub_handles[GSMTAP_SUB_ABIS] = find_dissector("gsm_a_dtap");
396 gsmtap_handle = create_dissector_handle(dissect_gsmtap, proto_gsmtap);
397 dissector_add_uint("udp.port", GSMTAP_UDP_PORT, gsmtap_handle);