1 /* packet-cattp.c
2 * Routines for packet dissection of
3 * ETSI TS 102 127 v6.13.0 (Release 6 / 2009-0r45)
4 * Card Application Toolkit - Transport Protocol over UDP
5 *
6 * Copyright 2014-2014 by Sebastian Kloeppel <sk [at] nakedape.net>
7 * Cristina E. Vintila <cristina.vintila [at] gmail.com>
8 *
9 * Wireshark - Network traffic analyzer
10 * By Gerald Combs <gerald@wireshark.org>
11 * Copyright 1998 Gerald Combs
12 *
13 * SPDX-License-Identifier: GPL-2.0-or-later
14 */
15 #include "config.h"
16
17 #include <epan/packet.h>
18 #include <epan/prefs.h>
19 #include <epan/expert.h>
20 #include <epan/in_cksum.h>
21
22 #define CATTP_SHORTNAME "CAT-TP"
23 #define CATTP_HBLEN 18
24
25 #define F_SYN 0x80
26 #define F_ACK 0x40
27 #define F_EAK 0x20
28 #define F_RST 0x10
29 #define F_NUL 0x08
30 #define F_SEG 0x04
31
32 /* bit masks for the first header byte. */
33 #define M_FLAGS 0xFC /* flags only, no version */
34 #define M_PDU_SYN 0xB8 /* SYN (ACK, SEG don't care) without version */
35 #define M_PDU_ACK 0xD0 /* ACK (EAK, SEG, NUL don't care) without version */
36 #define M_PDU_RST 0xBC /* RST (ACK don't care) without version */
37 #define M_VERSION 0x03 /* only Version */
38
39 #define ICCID_PREFIX 0x98
40
41 static int proto_cattp = -1;
42
43 static gint ett_cattp = -1;
44 static gint ett_cattp_id = -1;
45 static gint ett_cattp_flags = -1;
46 static gint ett_cattp_eaks = -1;
47
48 static int hf_cattp_flags = -1;
49
50 /* flag components */
51 static int hf_cattp_flag_syn = -1;
52 static int hf_cattp_flag_ack = -1;
53 static int hf_cattp_flag_eak = -1;
54 static int hf_cattp_flag_rst = -1;
55 static int hf_cattp_flag_nul = -1;
56 static int hf_cattp_flag_seg = -1;
57 static int hf_cattp_version = -1;
58
59 /* structure of flag components */
60 static int * const cattp_flags[] = {
61 &hf_cattp_flag_syn,
62 &hf_cattp_flag_ack,
63 &hf_cattp_flag_eak,
64 &hf_cattp_flag_rst,
65 &hf_cattp_flag_nul,
66 &hf_cattp_flag_seg,
67 &hf_cattp_version,
68 NULL
69 };
70
71 static int hf_cattp_hlen = -1;
72 static int hf_cattp_srcport = -1;
73 static int hf_cattp_dstport = -1;
74 static int hf_cattp_datalen = -1;
75 static int hf_cattp_seq = -1;
76 static int hf_cattp_ack = -1;
77 static int hf_cattp_windowsize = -1;
78 static int hf_cattp_checksum = -1;
79 static int hf_cattp_checksum_status = -1;
80 static int hf_cattp_identification = -1;
81 static int hf_cattp_iccid = -1;
82 static int hf_cattp_idlen = -1;
83 static int hf_cattp_maxpdu = -1;
84 static int hf_cattp_maxsdu = -1;
85 static int hf_cattp_rc = -1;
86 static int hf_cattp_eaklen = -1;
87 static int hf_cattp_eaks = -1;
88
89 static expert_field ei_cattp_checksum = EI_INIT;
90
91 /* Preference to control whether to check the CATTP checksum */
92 static gboolean cattp_check_checksum = TRUE;
93
94 /* Reason code mapping */
95 static const value_string cattp_reset_reason[] = {
96 { 0, "Normal Ending" },
97 { 1, "Connection set-up failed, illegal parameters" },
98 { 2, "Temporarily unable to set up this connection" },
99 { 3, "Requested Port not available" },
100 { 4, "Unexpected PDU received" },
101 { 5, "Maximum retries exceeded" },
102 { 6, "Version not supported" },
103 { 7, "RFU" },
104 { 0, NULL }
105 };
106
107 static const unit_name_string units_pdu = { "PDU", "PDUs" };
108
109 /* Forward declartion due to use of heuristic dissection preference. */
110 void proto_reg_handoff_cattp(void);
111 void proto_register_cattp(void);
112
113 /* Dissection of SYN PDUs */
114 static guint32
dissect_cattp_synpdu(tvbuff_t * tvb,packet_info * pinfo,proto_tree * cattp_tree,guint32 offset)115 dissect_cattp_synpdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *cattp_tree, guint32 offset)
116 {
117 proto_item *idi, *id_tree;
118 guint8 idlen;
119
120 proto_tree_add_item(cattp_tree, hf_cattp_maxpdu, tvb, offset, 2, ENC_BIG_ENDIAN);
121 offset += 2;
122
123 proto_tree_add_item(cattp_tree, hf_cattp_maxsdu, tvb, offset, 2, ENC_BIG_ENDIAN);
124 offset += 2;
125
126 idlen = tvb_get_guint8(tvb, offset);
127 idi = proto_tree_add_uint(cattp_tree, hf_cattp_idlen, tvb, offset, 1, idlen);
128 offset += 1;
129
130 col_append_fstr(pinfo->cinfo, COL_INFO, " IdLen=%u ", idlen);
131
132 id_tree = proto_item_add_subtree(idi, ett_cattp_id);
133
134 if (idlen > 0) {
135 guint8 first_id_byte;
136
137 first_id_byte = tvb_get_guint8(tvb, offset);
138 proto_tree_add_item(id_tree, hf_cattp_identification, tvb, offset, idlen, ENC_NA);
139
140 /* Optional code. Checks whether identification field may be an ICCID.
141 * It has to be considered to move this logic to another layer / dissector.
142 * However it is common to send ICCID as Identification for OTA download. */
143 if (idlen <= 10 && idlen >= 9 && ICCID_PREFIX == first_id_byte) {
144 wmem_strbuf_t *buf;
145 int i;
146
147 buf = wmem_strbuf_new(pinfo->pool, "");
148
149 /* switch nibbles */
150 for (i = 0; i < idlen; i++) {
151 guint8 c, n;
152
153 c = tvb_get_guint8(tvb, offset + i);
154 n = ((c & 0xF0) >> 4) + ((c & 0x0F) << 4);
155 wmem_strbuf_append_printf(buf, "%02X", n);
156 }
157
158 proto_tree_add_string(id_tree, hf_cattp_iccid, tvb, offset,
159 idlen, wmem_strbuf_get_str(buf));
160 }
161 offset += idlen;
162 }
163 return offset;
164 }
165
166 /* Dissection of Extended Acknowledgement PDUs */
167 static guint32
dissect_cattp_eakpdu(tvbuff_t * tvb,packet_info * pinfo,proto_tree * cattp_tree,guint32 offset,guint8 hlen)168 dissect_cattp_eakpdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *cattp_tree, guint32 offset, guint8 hlen)
169 {
170 proto_item *eaki;
171 guint8 eak_count;
172
173 eak_count = (hlen - offset) >> 1;
174 eaki = proto_tree_add_uint(cattp_tree, hf_cattp_eaklen, tvb, offset, eak_count * 2, eak_count);
175
176 if (eak_count > 0) {
177 proto_item *eak_tree;
178 int i;
179
180 col_append_fstr(pinfo->cinfo, COL_INFO, " EAKs=%u", eak_count);
181 eak_tree = proto_item_add_subtree(eaki, ett_cattp_eaks);
182
183 for (i = 0; i < eak_count; i++) {
184 proto_tree_add_item(eak_tree, hf_cattp_eaks, tvb, offset, 2, ENC_BIG_ENDIAN);
185 offset += 2;
186 }
187 }
188
189 return offset;
190 }
191
192 /* Dissection of Extended Acknowledgement PDUs */
193 static guint32
dissect_cattp_rstpdu(tvbuff_t * tvb,packet_info * pinfo,proto_tree * cattp_tree,guint32 offset)194 dissect_cattp_rstpdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *cattp_tree, guint32 offset)
195 {
196 guint8 rc;
197 const gchar *rc_str;
198
199 rc = tvb_get_guint8(tvb, offset); /* reason code of RST */
200 rc_str = val_to_str(rc, cattp_reset_reason, "Unknown reason code: 0x%02x");
201 col_append_fstr(pinfo->cinfo, COL_INFO, " Reason=\"%s\" ", rc_str);
202
203 proto_tree_add_item(cattp_tree, hf_cattp_rc, tvb, offset, 1, ENC_BIG_ENDIAN);
204 return ++offset;
205 }
206
207 /* Dissection of the base header */
208 static int
dissect_cattp(tvbuff_t * tvb,packet_info * pinfo,proto_tree * tree,void * data _U_)209 dissect_cattp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
210 {
211 const char *pdutype = "[Unknown PDU]";
212 proto_item *ti, *cattp_tree;
213 guint32 offset;
214 vec_t cksum_vec[1];
215 int header_offset;
216 guint cksum_data_len;
217 guint8 flags, first_byte, hlen, ver;
218 guint16 plen, ackno, seqno, wsize, sport, dport;
219
220 col_set_str(pinfo->cinfo, COL_PROTOCOL, CATTP_SHORTNAME);
221
222 /* Clear out stuff in the info column */
223 col_clear(pinfo->cinfo, COL_INFO);
224
225 hlen = tvb_get_guint8(tvb, 3); /* lookahead header len. */
226
227 offset = 0;
228 ti = proto_tree_add_protocol_format(tree, proto_cattp, tvb, offset, hlen,
229 "Card Application Toolkit Transport Protocol");
230
231 cattp_tree = proto_item_add_subtree(ti, ett_cattp);
232
233 /* render flags tree */
234 first_byte = tvb_get_guint8(tvb, offset);
235 flags = first_byte & M_FLAGS; /* discard version from first byte for flags */
236 ver = first_byte & M_VERSION; /* discard flags for version */
237 proto_tree_add_bitmask(cattp_tree, tvb, offset, hf_cattp_flags, ett_cattp_flags, cattp_flags, ENC_BIG_ENDIAN);
238 offset += 3; /* skip RFU and header len */
239
240 /* Header length, varies for SYN(identification) and EAKs */
241 proto_tree_add_uint(cattp_tree, hf_cattp_hlen, tvb, offset, 1, hlen);
242 offset += 1;
243
244 /* Parse cattp source port. */
245 sport = tvb_get_ntohs(tvb, offset);
246 proto_tree_add_uint(cattp_tree, hf_cattp_srcport, tvb, offset, 2, sport);
247 offset += 2;
248
249 /* Parse cattp destination port. */
250 dport = tvb_get_ntohs(tvb, offset);
251 proto_tree_add_uint(cattp_tree, hf_cattp_dstport, tvb, offset, 2, dport);
252 offset += 2;
253
254 proto_item_append_text(ti, " (v%u, Src Port: %u, Dst Port: %u)", ver, sport, dport);
255 col_add_fstr(pinfo->cinfo, COL_INFO, "%u > %u ", sport, dport);
256
257 /* Parse length of payload. */
258 plen = tvb_get_ntohs(tvb, offset);
259 proto_tree_add_uint(cattp_tree, hf_cattp_datalen, tvb, offset, 2, plen);
260 offset += 2;
261
262 /* Parse sequence number. */
263 seqno = tvb_get_ntohs(tvb, offset);
264 proto_tree_add_uint(cattp_tree, hf_cattp_seq, tvb, offset, 2, seqno);
265 offset += 2;
266
267 /* Parse acknowledgement number. */
268 ackno = tvb_get_ntohs(tvb, offset);
269 proto_tree_add_uint(cattp_tree, hf_cattp_ack, tvb, offset, 2, ackno);
270 offset += 2;
271
272 /* Parse window size. */
273 wsize = tvb_get_ntohs(tvb, offset);
274 proto_tree_add_uint(cattp_tree, hf_cattp_windowsize, tvb, offset, 2, wsize);
275 offset += 2;
276
277 if (flags & F_SYN)
278 pdutype = "[SYN PDU]";
279 else if (flags & F_ACK)
280 pdutype = "[ACK PDU]";
281 else if (flags & F_RST)
282 pdutype = "[RST PDU]";
283
284 col_append_fstr(pinfo->cinfo, COL_INFO, "%s Flags=0x%02X Ack=%u Seq=%u WSize=%u", pdutype, flags, ackno, seqno, wsize);
285
286 /* Parse and verify checksum */
287 header_offset = 0;
288 cksum_data_len = hlen + plen;
289 if (!cattp_check_checksum) {
290 /* We have turned checksum checking off; we do NOT checksum it. */
291 proto_tree_add_checksum(cattp_tree, tvb, offset, hf_cattp_checksum, hf_cattp_checksum_status, &ei_cattp_checksum,
292 pinfo, 0, ENC_BIG_ENDIAN, PROTO_CHECKSUM_NO_FLAGS);
293 } else {
294 /* We haven't turned checksum checking off; checksum it. */
295
296 /* Unlike TCP, CATTP does not make use of a pseudo-header for checksum */
297 SET_CKSUM_VEC_TVB(cksum_vec[0], tvb, header_offset, cksum_data_len);
298 proto_tree_add_checksum(cattp_tree, tvb, offset, hf_cattp_checksum, hf_cattp_checksum_status, &ei_cattp_checksum,
299 pinfo, in_cksum(cksum_vec, 1), ENC_BIG_ENDIAN, PROTO_CHECKSUM_VERIFY|PROTO_CHECKSUM_IN_CKSUM);
300 } /* End of checksum code */
301 offset += 2;
302
303 if (flags & F_SYN)
304 offset = dissect_cattp_synpdu(tvb, pinfo, cattp_tree, offset);
305 else if (flags & F_EAK)
306 offset = dissect_cattp_eakpdu(tvb, pinfo, cattp_tree, offset, hlen);
307 else if (flags & F_RST)
308 offset = dissect_cattp_rstpdu(tvb, pinfo, cattp_tree, offset);
309 /* for other PDU types nothing special to be displayed in detail tree. */
310
311 if (plen > 0) { /* Call generic data handle if data exists. */
312 col_append_fstr(pinfo->cinfo, COL_INFO, " DataLen=%u", plen);
313 tvb = tvb_new_subset_remaining(tvb, offset);
314 call_data_dissector(tvb, pinfo, tree);
315 }
316 return tvb_captured_length(tvb);
317 }
318
319 /* The heuristic dissector function checks if the UDP packet may be a cattp packet */
320 static gboolean
dissect_cattp_heur(tvbuff_t * tvb,packet_info * pinfo,proto_tree * tree,void * data)321 dissect_cattp_heur(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
322 {
323 if (tvb_captured_length(tvb) >= CATTP_HBLEN) { /* check of data is big enough for base header. */
324 guint8 flags, ver, hlen;
325 guint16 plen;
326
327 hlen = tvb_get_guint8(tvb, 3); /* header len */
328 plen = tvb_get_ntohs(tvb, 8); /* payload len */
329
330 if (hlen+plen != tvb_reported_length(tvb)) /* check if data length is ok. */
331 return FALSE;
332
333 /* ETSI TS 102 127 V15.0.0 and earlier releases say explicitly that
334 the version bits must be 0. */
335 ver = tvb_get_guint8(tvb, 0) & M_VERSION;
336 if (ver != 0)
337 return FALSE;
338
339 flags = tvb_get_guint8(tvb, 0) & M_FLAGS;
340 if ( (flags & M_PDU_SYN) == F_SYN ||
341 (flags & M_PDU_RST) == F_RST ||
342 (flags & M_PDU_ACK) == F_ACK ) { /* check if flag combi is valid */
343 dissect_cattp(tvb, pinfo, tree, data);
344 return TRUE;
345 }
346 }
347 return FALSE;
348 }
349
350 /* Function to register the dissector, called by infrastructure. */
351 void
proto_register_cattp(void)352 proto_register_cattp(void)
353 {
354 static hf_register_info hf[] = {
355 {
356 &hf_cattp_flags,
357 {
358 "Flags", "cattp.flags", FT_UINT8, BASE_HEX, NULL, 0x0,
359 NULL, HFILL
360 }
361 },
362 {
363 &hf_cattp_flag_syn,
364 {
365 "Synchronize Flag", "cattp.flags.syn", FT_UINT8, BASE_DEC, NULL, F_SYN,
366 NULL, HFILL
367 }
368 },
369 {
370 &hf_cattp_flag_ack,
371 {
372 "Acknowledge Flag", "cattp.flags.ack", FT_UINT8, BASE_DEC, NULL, F_ACK,
373 NULL, HFILL
374 }
375 },
376 {
377 &hf_cattp_flag_eak,
378 {
379 "Extended Acknowledge Flag", "cattp.flags.eak", FT_UINT8, BASE_DEC, NULL, F_EAK,
380 NULL, HFILL
381 }
382 },
383 {
384 &hf_cattp_flag_rst,
385 {
386 "Reset Flag", "cattp.flags.rst", FT_UINT8, BASE_DEC, NULL, F_RST,
387 NULL, HFILL
388 }
389 },
390 {
391 &hf_cattp_flag_nul,
392 {
393 "NULL Flag", "cattp.flags.nul", FT_UINT8, BASE_DEC, NULL, F_NUL,
394 NULL, HFILL
395 }
396 },
397 {
398 &hf_cattp_flag_seg,
399 {
400 "Segmentation Flag", "cattp.flags.seg", FT_UINT8, BASE_DEC, NULL, F_SEG,
401 NULL, HFILL
402 }
403 },
404 {
405 &hf_cattp_version,
406 {
407 "Version", "cattp.version", FT_UINT8, BASE_HEX, NULL, M_VERSION,
408 NULL, HFILL
409 }
410 },
411 {
412 &hf_cattp_hlen,
413 {
414 "Header Length", "cattp.hlen", FT_UINT8, BASE_DEC, NULL, 0x0,
415 NULL, HFILL
416 }
417 },
418 {
419 &hf_cattp_srcport,
420 {
421 "Source Port", "cattp.srcport", FT_UINT16, BASE_DEC, NULL, 0x0,
422 NULL, HFILL
423 }
424 },
425 {
426 &hf_cattp_dstport,
427 {
428 "Destination Port", "cattp.dstport", FT_UINT16, BASE_DEC, NULL, 0x0,
429 NULL, HFILL
430 }
431 },
432 {
433 &hf_cattp_datalen,
434 {
435 "Data Length", "cattp.datalen", FT_UINT16, BASE_DEC, NULL, 0x0,
436 NULL, HFILL
437 }
438 },
439 {
440 &hf_cattp_seq,
441 {
442 "Sequence Number", "cattp.seq", FT_UINT16, BASE_DEC, NULL, 0x0,
443 NULL, HFILL
444 }
445 },
446 {
447 &hf_cattp_ack,
448 {
449 "Acknowledgement Number", "cattp.ack", FT_UINT16, BASE_DEC, NULL, 0x0,
450 NULL, HFILL
451 }
452 },
453 {
454 &hf_cattp_windowsize,
455 {
456 "Window Size", "cattp.windowsize", FT_UINT16, BASE_DEC, NULL, 0x0,
457 NULL, HFILL
458 }
459 },
460 {
461 &hf_cattp_checksum,
462 {
463 "Checksum", "cattp.checksum", FT_UINT16, BASE_HEX, NULL, 0x0,
464 NULL, HFILL
465 }
466 },
467 {
468 &hf_cattp_checksum_status,
469 {
470 "Checksum Status", "cattp.checksum.status", FT_UINT8, BASE_NONE, VALS(proto_checksum_vals), 0x0,
471 NULL, HFILL
472 }
473 },
474 {
475 &hf_cattp_identification,
476 {
477 "Identification", "cattp.identification", FT_BYTES, BASE_NONE, NULL, 0x0,
478 NULL, HFILL
479 }
480 },
481 {
482 &hf_cattp_iccid,
483 {
484 "ICCID", "cattp.iccid", FT_STRING, BASE_NONE, NULL, 0x0,
485 NULL, HFILL
486 }
487 },
488 {
489 &hf_cattp_maxpdu,
490 {
491 "Maxpdu", "cattp.maxpdu", FT_UINT16, BASE_DEC, NULL, 0x0,
492 NULL, HFILL
493 }
494 },
495 {
496 &hf_cattp_maxsdu,
497 {
498 "Maxsdu", "cattp.maxsdu", FT_UINT16, BASE_DEC, NULL, 0x0,
499 NULL, HFILL
500 }
501 },
502 {
503 &hf_cattp_rc,
504 {
505 "Reason Code", "cattp.rc", FT_UINT8, BASE_DEC, VALS(cattp_reset_reason), 0x0,
506 NULL, HFILL
507 }
508 },
509 {
510 &hf_cattp_idlen,
511 {
512 "Identification Length", "cattp.idlen", FT_UINT8, BASE_DEC, NULL, 0x0,
513 NULL, HFILL
514 }
515 },
516 {
517 &hf_cattp_eaks,
518 {
519 "Acknowledgement Number", "cattp.eak", FT_UINT16, BASE_DEC, NULL, 0x0,
520 NULL, HFILL
521 }
522 },
523 {
524 &hf_cattp_eaklen,
525 {
526 "Extended Acknowledgement Numbers", "cattp.eaks", FT_UINT16, BASE_DEC|BASE_UNIT_STRING, &units_pdu, 0x0,
527 NULL, HFILL
528 }
529 }
530 };
531
532 /* Setup protocol subtree array */
533 static gint *ett[] = {
534 &ett_cattp,
535 &ett_cattp_flags,
536 &ett_cattp_id,
537 &ett_cattp_eaks
538 };
539
540 static ei_register_info ei[] = {
541 { &ei_cattp_checksum, { "cattp.bad_checksum", PI_CHECKSUM, PI_ERROR, "Bad checksum", EXPFILL }},
542 };
543
544 module_t *cattp_module;
545 expert_module_t* expert_cattp;
546
547 proto_cattp = proto_register_protocol (
548 "ETSI Card Application Toolkit Transport Protocol", /* name */
549 CATTP_SHORTNAME, /* short name */
550 "cattp" /* abbrev */
551 );
552
553 proto_register_field_array(proto_cattp, hf, array_length(hf));
554 proto_register_subtree_array(ett, array_length(ett));
555 expert_cattp = expert_register_protocol(proto_cattp);
556 expert_register_field_array(expert_cattp, ei, array_length(ei));
557
558 cattp_module = prefs_register_protocol(proto_cattp, NULL);
559 prefs_register_bool_preference(cattp_module, "checksum",
560 "Validate checksum of all messages",
561 "Whether the checksum of all messages should be validated or not",
562 &cattp_check_checksum);
563
564 prefs_register_obsolete_preference(cattp_module, "enable");
565 }
566
567 /* Handoff */
568 void
proto_reg_handoff_cattp(void)569 proto_reg_handoff_cattp(void)
570 {
571 dissector_handle_t cattp_handle;
572
573 /* Create dissector handle */
574 cattp_handle = create_dissector_handle(dissect_cattp, proto_cattp);
575
576 heur_dissector_add("udp", dissect_cattp_heur, "CAT-TP over UDP", "cattp_udp", proto_cattp, HEURISTIC_DISABLE);
577 dissector_add_for_decode_as_with_preference("udp.port", cattp_handle);
578 }
579
580 /*
581 * Editor modelines - https://www.wireshark.org/tools/modelines.html
582 *
583 * Local variables:
584 * c-basic-offset: 4
585 * tab-width: 8
586 * indent-tabs-mode: nil
587 * End:
588 *
589 * vi: set shiftwidth=4 tabstop=8 expandtab:
590 * :indentSize=4:tabSize=8:noTabs=true:
591 */
592