diff options
Diffstat (limited to 'src/util/dnsparser.c')
-rw-r--r-- | src/util/dnsparser.c | 1458 |
1 files changed, 1458 insertions, 0 deletions
diff --git a/src/util/dnsparser.c b/src/util/dnsparser.c new file mode 100644 index 000000000..24f1b18cf --- /dev/null +++ b/src/util/dnsparser.c | |||
@@ -0,0 +1,1458 @@ | |||
1 | /* | ||
2 | This file is part of GNUnet | ||
3 | Copyright (C) 2010-2014 GNUnet e.V. | ||
4 | |||
5 | GNUnet is free software: you can redistribute it and/or modify it | ||
6 | under the terms of the GNU Affero General Public License as published | ||
7 | by the Free Software Foundation, either version 3 of the License, | ||
8 | or (at your option) any later version. | ||
9 | |||
10 | GNUnet is distributed in the hope that it will be useful, but | ||
11 | WITHOUT ANY WARRANTY; without even the implied warranty of | ||
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
13 | Affero General Public License for more details. | ||
14 | |||
15 | You should have received a copy of the GNU Affero General Public License | ||
16 | along with this program. If not, see <http://www.gnu.org/licenses/>. | ||
17 | */ | ||
18 | |||
19 | /** | ||
20 | * @file dns/dnsparser.c | ||
21 | * @brief helper library to parse DNS packets. | ||
22 | * @author Philipp Toelke | ||
23 | * @author Christian Grothoff | ||
24 | */ | ||
25 | #include "platform.h" | ||
26 | #include <idna.h> | ||
27 | #if WINDOWS | ||
28 | #include <idn-free.h> | ||
29 | #endif | ||
30 | #include "gnunet_util_lib.h" | ||
31 | |||
32 | |||
33 | /** | ||
34 | * Check if a label in UTF-8 format can be coded into valid IDNA. | ||
35 | * This can fail if the ASCII-conversion becomes longer than 63 characters. | ||
36 | * | ||
37 | * @param label label to check (UTF-8 string) | ||
38 | * @return #GNUNET_OK if the label can be converted to IDNA, | ||
39 | * #GNUNET_SYSERR if the label is not valid for DNS names | ||
40 | */ | ||
41 | int | ||
42 | GNUNET_DNSPARSER_check_label (const char *label) | ||
43 | { | ||
44 | char *output; | ||
45 | size_t slen; | ||
46 | |||
47 | if (NULL != strchr (label, '.')) | ||
48 | return GNUNET_SYSERR; /* not a label! Did you mean GNUNET_DNSPARSER_check_name? */ | ||
49 | if (IDNA_SUCCESS != | ||
50 | idna_to_ascii_8z (label, &output, IDNA_ALLOW_UNASSIGNED)) | ||
51 | return GNUNET_SYSERR; | ||
52 | slen = strlen (output); | ||
53 | #if WINDOWS | ||
54 | idn_free (output); | ||
55 | #else | ||
56 | free (output); | ||
57 | #endif | ||
58 | return (slen > 63) ? GNUNET_SYSERR : GNUNET_OK; | ||
59 | } | ||
60 | |||
61 | |||
62 | /** | ||
63 | * Check if a label in UTF-8 format can be coded into valid IDNA. | ||
64 | * This can fail if the ASCII-conversion becomes longer than 253 characters. | ||
65 | * | ||
66 | * @param name name to check (UTF-8 string) | ||
67 | * @return #GNUNET_OK if the label can be converted to IDNA, | ||
68 | * #GNUNET_SYSERR if the label is not valid for DNS names | ||
69 | */ | ||
70 | int | ||
71 | GNUNET_DNSPARSER_check_name (const char *name) | ||
72 | { | ||
73 | char *ldup; | ||
74 | char *output; | ||
75 | size_t slen; | ||
76 | char *tok; | ||
77 | |||
78 | ldup = GNUNET_strdup (name); | ||
79 | for (tok = strtok (ldup, "."); NULL != tok; tok = strtok (NULL, ".")) | ||
80 | if (GNUNET_OK != | ||
81 | GNUNET_DNSPARSER_check_label (tok)) | ||
82 | { | ||
83 | GNUNET_free (ldup); | ||
84 | return GNUNET_SYSERR; | ||
85 | } | ||
86 | GNUNET_free (ldup); | ||
87 | if (IDNA_SUCCESS != | ||
88 | idna_to_ascii_8z (name, &output, IDNA_ALLOW_UNASSIGNED)) | ||
89 | return GNUNET_SYSERR; | ||
90 | slen = strlen (output); | ||
91 | #if WINDOWS | ||
92 | idn_free (output); | ||
93 | #else | ||
94 | free (output); | ||
95 | #endif | ||
96 | return (slen > 253) ? GNUNET_SYSERR : GNUNET_OK; | ||
97 | } | ||
98 | |||
99 | |||
100 | /** | ||
101 | * Free SOA information record. | ||
102 | * | ||
103 | * @param soa record to free | ||
104 | */ | ||
105 | void | ||
106 | GNUNET_DNSPARSER_free_soa (struct GNUNET_DNSPARSER_SoaRecord *soa) | ||
107 | { | ||
108 | if (NULL == soa) | ||
109 | return; | ||
110 | GNUNET_free_non_null (soa->mname); | ||
111 | GNUNET_free_non_null (soa->rname); | ||
112 | GNUNET_free (soa); | ||
113 | } | ||
114 | |||
115 | |||
116 | /** | ||
117 | * Free CERT information record. | ||
118 | * | ||
119 | * @param cert record to free | ||
120 | */ | ||
121 | void | ||
122 | GNUNET_DNSPARSER_free_cert (struct GNUNET_DNSPARSER_CertRecord *cert) | ||
123 | { | ||
124 | if (NULL == cert) | ||
125 | return; | ||
126 | GNUNET_free_non_null (cert->certificate_data); | ||
127 | GNUNET_free (cert); | ||
128 | } | ||
129 | |||
130 | |||
131 | /** | ||
132 | * Free SRV information record. | ||
133 | * | ||
134 | * @param srv record to free | ||
135 | */ | ||
136 | void | ||
137 | GNUNET_DNSPARSER_free_srv (struct GNUNET_DNSPARSER_SrvRecord *srv) | ||
138 | { | ||
139 | if (NULL == srv) | ||
140 | return; | ||
141 | GNUNET_free_non_null (srv->target); | ||
142 | GNUNET_free (srv); | ||
143 | } | ||
144 | |||
145 | |||
146 | /** | ||
147 | * Free MX information record. | ||
148 | * | ||
149 | * @param mx record to free | ||
150 | */ | ||
151 | void | ||
152 | GNUNET_DNSPARSER_free_mx (struct GNUNET_DNSPARSER_MxRecord *mx) | ||
153 | { | ||
154 | if (NULL == mx) | ||
155 | return; | ||
156 | GNUNET_free_non_null (mx->mxhost); | ||
157 | GNUNET_free (mx); | ||
158 | } | ||
159 | |||
160 | |||
161 | /** | ||
162 | * Free the given DNS record. | ||
163 | * | ||
164 | * @param r record to free | ||
165 | */ | ||
166 | void | ||
167 | GNUNET_DNSPARSER_free_record (struct GNUNET_DNSPARSER_Record *r) | ||
168 | { | ||
169 | GNUNET_free_non_null (r->name); | ||
170 | switch (r->type) | ||
171 | { | ||
172 | case GNUNET_DNSPARSER_TYPE_MX: | ||
173 | GNUNET_DNSPARSER_free_mx (r->data.mx); | ||
174 | break; | ||
175 | case GNUNET_DNSPARSER_TYPE_SOA: | ||
176 | GNUNET_DNSPARSER_free_soa (r->data.soa); | ||
177 | break; | ||
178 | case GNUNET_DNSPARSER_TYPE_SRV: | ||
179 | GNUNET_DNSPARSER_free_srv (r->data.srv); | ||
180 | break; | ||
181 | case GNUNET_DNSPARSER_TYPE_CERT: | ||
182 | GNUNET_DNSPARSER_free_cert (r->data.cert); | ||
183 | break; | ||
184 | case GNUNET_DNSPARSER_TYPE_NS: | ||
185 | case GNUNET_DNSPARSER_TYPE_CNAME: | ||
186 | case GNUNET_DNSPARSER_TYPE_PTR: | ||
187 | GNUNET_free_non_null (r->data.hostname); | ||
188 | break; | ||
189 | default: | ||
190 | GNUNET_free_non_null (r->data.raw.data); | ||
191 | break; | ||
192 | } | ||
193 | } | ||
194 | |||
195 | |||
196 | /** | ||
197 | * Parse name inside of a DNS query or record. | ||
198 | * | ||
199 | * @param udp_payload entire UDP payload | ||
200 | * @param udp_payload_length length of @a udp_payload | ||
201 | * @param off pointer to the offset of the name to parse in the udp_payload (to be | ||
202 | * incremented by the size of the name) | ||
203 | * @param depth current depth of our recursion (to prevent stack overflow) | ||
204 | * @return name as 0-terminated C string on success, NULL if the payload is malformed | ||
205 | */ | ||
206 | static char * | ||
207 | parse_name (const char *udp_payload, | ||
208 | size_t udp_payload_length, | ||
209 | size_t *off, | ||
210 | unsigned int depth) | ||
211 | { | ||
212 | const uint8_t *input = (const uint8_t *) udp_payload; | ||
213 | char *ret; | ||
214 | char *tmp; | ||
215 | char *xstr; | ||
216 | uint8_t len; | ||
217 | size_t xoff; | ||
218 | char *utf8; | ||
219 | Idna_rc rc; | ||
220 | |||
221 | ret = GNUNET_strdup (""); | ||
222 | while (1) | ||
223 | { | ||
224 | if (*off >= udp_payload_length) | ||
225 | { | ||
226 | GNUNET_break_op (0); | ||
227 | goto error; | ||
228 | } | ||
229 | len = input[*off]; | ||
230 | if (0 == len) | ||
231 | { | ||
232 | (*off)++; | ||
233 | break; | ||
234 | } | ||
235 | if (len < 64) | ||
236 | { | ||
237 | if (*off + 1 + len > udp_payload_length) | ||
238 | { | ||
239 | GNUNET_break_op (0); | ||
240 | goto error; | ||
241 | } | ||
242 | GNUNET_asprintf (&tmp, | ||
243 | "%.*s", | ||
244 | (int) len, | ||
245 | &udp_payload[*off + 1]); | ||
246 | if (IDNA_SUCCESS != | ||
247 | (rc = idna_to_unicode_8z8z (tmp, &utf8, IDNA_ALLOW_UNASSIGNED))) | ||
248 | { | ||
249 | GNUNET_log (GNUNET_ERROR_TYPE_INFO, | ||
250 | _("Failed to convert DNS IDNA name `%s' to UTF-8: %s\n"), | ||
251 | tmp, | ||
252 | idna_strerror (rc)); | ||
253 | GNUNET_free (tmp); | ||
254 | GNUNET_asprintf (&tmp, | ||
255 | "%s%.*s.", | ||
256 | ret, | ||
257 | (int) len, | ||
258 | &udp_payload[*off + 1]); | ||
259 | } | ||
260 | else | ||
261 | { | ||
262 | GNUNET_free (tmp); | ||
263 | GNUNET_asprintf (&tmp, | ||
264 | "%s%s.", | ||
265 | ret, | ||
266 | utf8); | ||
267 | #if WINDOWS | ||
268 | idn_free (utf8); | ||
269 | #else | ||
270 | free (utf8); | ||
271 | #endif | ||
272 | } | ||
273 | GNUNET_free (ret); | ||
274 | ret = tmp; | ||
275 | *off += 1 + len; | ||
276 | } | ||
277 | else if ((64 | 128) == (len & (64 | 128)) ) | ||
278 | { | ||
279 | if (depth > 32) | ||
280 | { | ||
281 | GNUNET_break_op (0); | ||
282 | goto error; /* hard bound on stack to prevent "infinite" recursion, disallow! */ | ||
283 | } | ||
284 | /* pointer to string */ | ||
285 | if (*off + 1 > udp_payload_length) | ||
286 | { | ||
287 | GNUNET_break_op (0); | ||
288 | goto error; | ||
289 | } | ||
290 | xoff = ((len - (64 | 128)) << 8) + input[*off+1]; | ||
291 | xstr = parse_name (udp_payload, | ||
292 | udp_payload_length, | ||
293 | &xoff, | ||
294 | depth + 1); | ||
295 | if (NULL == xstr) | ||
296 | { | ||
297 | GNUNET_break_op (0); | ||
298 | goto error; | ||
299 | } | ||
300 | GNUNET_asprintf (&tmp, | ||
301 | "%s%s.", | ||
302 | ret, | ||
303 | xstr); | ||
304 | GNUNET_free (ret); | ||
305 | GNUNET_free (xstr); | ||
306 | ret = tmp; | ||
307 | if (strlen (ret) > udp_payload_length) | ||
308 | { | ||
309 | GNUNET_break_op (0); | ||
310 | goto error; /* we are looping (building an infinite string) */ | ||
311 | } | ||
312 | *off += 2; | ||
313 | /* pointers always terminate names */ | ||
314 | break; | ||
315 | } | ||
316 | else | ||
317 | { | ||
318 | /* neither pointer nor inline string, not supported... */ | ||
319 | GNUNET_break_op (0); | ||
320 | goto error; | ||
321 | } | ||
322 | } | ||
323 | if (0 < strlen(ret)) | ||
324 | ret[strlen(ret)-1] = '\0'; /* eat tailing '.' */ | ||
325 | return ret; | ||
326 | error: | ||
327 | GNUNET_break_op (0); | ||
328 | GNUNET_free (ret); | ||
329 | return NULL; | ||
330 | } | ||
331 | |||
332 | |||
333 | /** | ||
334 | * Parse name inside of a DNS query or record. | ||
335 | * | ||
336 | * @param udp_payload entire UDP payload | ||
337 | * @param udp_payload_length length of @a udp_payload | ||
338 | * @param off pointer to the offset of the name to parse in the udp_payload (to be | ||
339 | * incremented by the size of the name) | ||
340 | * @return name as 0-terminated C string on success, NULL if the payload is malformed | ||
341 | */ | ||
342 | char * | ||
343 | GNUNET_DNSPARSER_parse_name (const char *udp_payload, | ||
344 | size_t udp_payload_length, | ||
345 | size_t *off) | ||
346 | { | ||
347 | return parse_name (udp_payload, udp_payload_length, off, 0); | ||
348 | } | ||
349 | |||
350 | |||
351 | /** | ||
352 | * Parse a DNS query entry. | ||
353 | * | ||
354 | * @param udp_payload entire UDP payload | ||
355 | * @param udp_payload_length length of @a udp_payload | ||
356 | * @param off pointer to the offset of the query to parse in the udp_payload (to be | ||
357 | * incremented by the size of the query) | ||
358 | * @param q where to write the query information | ||
359 | * @return #GNUNET_OK on success, #GNUNET_SYSERR if the query is malformed | ||
360 | */ | ||
361 | int | ||
362 | GNUNET_DNSPARSER_parse_query (const char *udp_payload, | ||
363 | size_t udp_payload_length, | ||
364 | size_t *off, | ||
365 | struct GNUNET_DNSPARSER_Query *q) | ||
366 | { | ||
367 | char *name; | ||
368 | struct GNUNET_TUN_DnsQueryLine ql; | ||
369 | |||
370 | name = GNUNET_DNSPARSER_parse_name (udp_payload, | ||
371 | udp_payload_length, | ||
372 | off); | ||
373 | if (NULL == name) | ||
374 | { | ||
375 | GNUNET_break_op (0); | ||
376 | return GNUNET_SYSERR; | ||
377 | } | ||
378 | q->name = name; | ||
379 | if (*off + sizeof (struct GNUNET_TUN_DnsQueryLine) > udp_payload_length) | ||
380 | { | ||
381 | GNUNET_break_op (0); | ||
382 | return GNUNET_SYSERR; | ||
383 | } | ||
384 | GNUNET_memcpy (&ql, &udp_payload[*off], sizeof (ql)); | ||
385 | *off += sizeof (ql); | ||
386 | q->type = ntohs (ql.type); | ||
387 | q->dns_traffic_class = ntohs (ql.dns_traffic_class); | ||
388 | return GNUNET_OK; | ||
389 | } | ||
390 | |||
391 | |||
392 | /** | ||
393 | * Parse a DNS SOA record. | ||
394 | * | ||
395 | * @param udp_payload reference to UDP packet | ||
396 | * @param udp_payload_length length of @a udp_payload | ||
397 | * @param off pointer to the offset of the query to parse in the SOA record (to be | ||
398 | * incremented by the size of the record), unchanged on error | ||
399 | * @return the parsed SOA record, NULL on error | ||
400 | */ | ||
401 | struct GNUNET_DNSPARSER_SoaRecord * | ||
402 | GNUNET_DNSPARSER_parse_soa (const char *udp_payload, | ||
403 | size_t udp_payload_length, | ||
404 | size_t *off) | ||
405 | { | ||
406 | struct GNUNET_DNSPARSER_SoaRecord *soa; | ||
407 | struct GNUNET_TUN_DnsSoaRecord soa_bin; | ||
408 | size_t old_off; | ||
409 | |||
410 | old_off = *off; | ||
411 | soa = GNUNET_new (struct GNUNET_DNSPARSER_SoaRecord); | ||
412 | soa->mname = GNUNET_DNSPARSER_parse_name (udp_payload, | ||
413 | udp_payload_length, | ||
414 | off); | ||
415 | soa->rname = GNUNET_DNSPARSER_parse_name (udp_payload, | ||
416 | udp_payload_length, | ||
417 | off); | ||
418 | if ( (NULL == soa->mname) || | ||
419 | (NULL == soa->rname) || | ||
420 | (*off + sizeof (struct GNUNET_TUN_DnsSoaRecord) > udp_payload_length) ) | ||
421 | { | ||
422 | GNUNET_break_op (0); | ||
423 | GNUNET_DNSPARSER_free_soa (soa); | ||
424 | *off = old_off; | ||
425 | return NULL; | ||
426 | } | ||
427 | GNUNET_memcpy (&soa_bin, | ||
428 | &udp_payload[*off], | ||
429 | sizeof (struct GNUNET_TUN_DnsSoaRecord)); | ||
430 | soa->serial = ntohl (soa_bin.serial); | ||
431 | soa->refresh = ntohl (soa_bin.refresh); | ||
432 | soa->retry = ntohl (soa_bin.retry); | ||
433 | soa->expire = ntohl (soa_bin.expire); | ||
434 | soa->minimum_ttl = ntohl (soa_bin.minimum); | ||
435 | (*off) += sizeof (struct GNUNET_TUN_DnsSoaRecord); | ||
436 | return soa; | ||
437 | } | ||
438 | |||
439 | |||
440 | /** | ||
441 | * Parse a DNS MX record. | ||
442 | * | ||
443 | * @param udp_payload reference to UDP packet | ||
444 | * @param udp_payload_length length of @a udp_payload | ||
445 | * @param off pointer to the offset of the query to parse in the MX record (to be | ||
446 | * incremented by the size of the record), unchanged on error | ||
447 | * @return the parsed MX record, NULL on error | ||
448 | */ | ||
449 | struct GNUNET_DNSPARSER_MxRecord * | ||
450 | GNUNET_DNSPARSER_parse_mx (const char *udp_payload, | ||
451 | size_t udp_payload_length, | ||
452 | size_t *off) | ||
453 | { | ||
454 | struct GNUNET_DNSPARSER_MxRecord *mx; | ||
455 | uint16_t mxpref; | ||
456 | size_t old_off; | ||
457 | |||
458 | old_off = *off; | ||
459 | if (*off + sizeof (uint16_t) > udp_payload_length) | ||
460 | { | ||
461 | GNUNET_break_op (0); | ||
462 | return NULL; | ||
463 | } | ||
464 | GNUNET_memcpy (&mxpref, &udp_payload[*off], sizeof (uint16_t)); | ||
465 | (*off) += sizeof (uint16_t); | ||
466 | mx = GNUNET_new (struct GNUNET_DNSPARSER_MxRecord); | ||
467 | mx->preference = ntohs (mxpref); | ||
468 | mx->mxhost = GNUNET_DNSPARSER_parse_name (udp_payload, | ||
469 | udp_payload_length, | ||
470 | off); | ||
471 | if (NULL == mx->mxhost) | ||
472 | { | ||
473 | GNUNET_break_op (0); | ||
474 | GNUNET_DNSPARSER_free_mx (mx); | ||
475 | *off = old_off; | ||
476 | return NULL; | ||
477 | } | ||
478 | return mx; | ||
479 | } | ||
480 | |||
481 | |||
482 | /** | ||
483 | * Parse a DNS SRV record. | ||
484 | * | ||
485 | * @param udp_payload reference to UDP packet | ||
486 | * @param udp_payload_length length of @a udp_payload | ||
487 | * @param off pointer to the offset of the query to parse in the SRV record (to be | ||
488 | * incremented by the size of the record), unchanged on error | ||
489 | * @return the parsed SRV record, NULL on error | ||
490 | */ | ||
491 | struct GNUNET_DNSPARSER_SrvRecord * | ||
492 | GNUNET_DNSPARSER_parse_srv (const char *udp_payload, | ||
493 | size_t udp_payload_length, | ||
494 | size_t *off) | ||
495 | { | ||
496 | struct GNUNET_DNSPARSER_SrvRecord *srv; | ||
497 | struct GNUNET_TUN_DnsSrvRecord srv_bin; | ||
498 | size_t old_off; | ||
499 | |||
500 | old_off = *off; | ||
501 | if (*off + sizeof (struct GNUNET_TUN_DnsSrvRecord) > udp_payload_length) | ||
502 | return NULL; | ||
503 | GNUNET_memcpy (&srv_bin, | ||
504 | &udp_payload[*off], | ||
505 | sizeof (struct GNUNET_TUN_DnsSrvRecord)); | ||
506 | (*off) += sizeof (struct GNUNET_TUN_DnsSrvRecord); | ||
507 | srv = GNUNET_new (struct GNUNET_DNSPARSER_SrvRecord); | ||
508 | srv->priority = ntohs (srv_bin.prio); | ||
509 | srv->weight = ntohs (srv_bin.weight); | ||
510 | srv->port = ntohs (srv_bin.port); | ||
511 | srv->target = GNUNET_DNSPARSER_parse_name (udp_payload, | ||
512 | udp_payload_length, | ||
513 | off); | ||
514 | if (NULL == srv->target) | ||
515 | { | ||
516 | GNUNET_DNSPARSER_free_srv (srv); | ||
517 | *off = old_off; | ||
518 | return NULL; | ||
519 | } | ||
520 | return srv; | ||
521 | } | ||
522 | |||
523 | |||
524 | /** | ||
525 | * Parse a DNS CERT record. | ||
526 | * | ||
527 | * @param udp_payload reference to UDP packet | ||
528 | * @param udp_payload_length length of @a udp_payload | ||
529 | * @param off pointer to the offset of the query to parse in the CERT record (to be | ||
530 | * incremented by the size of the record), unchanged on error | ||
531 | * @return the parsed CERT record, NULL on error | ||
532 | */ | ||
533 | struct GNUNET_DNSPARSER_CertRecord * | ||
534 | GNUNET_DNSPARSER_parse_cert (const char *udp_payload, | ||
535 | size_t udp_payload_length, | ||
536 | size_t *off) | ||
537 | { | ||
538 | struct GNUNET_DNSPARSER_CertRecord *cert; | ||
539 | struct GNUNET_TUN_DnsCertRecord dcert; | ||
540 | |||
541 | if (*off + sizeof (struct GNUNET_TUN_DnsCertRecord) >= udp_payload_length) | ||
542 | { | ||
543 | GNUNET_break_op (0); | ||
544 | return NULL; | ||
545 | } | ||
546 | GNUNET_memcpy (&dcert, | ||
547 | &udp_payload[*off], | ||
548 | sizeof (struct GNUNET_TUN_DnsCertRecord)); | ||
549 | (*off) += sizeof (struct GNUNET_TUN_DnsCertRecord); | ||
550 | cert = GNUNET_new (struct GNUNET_DNSPARSER_CertRecord); | ||
551 | cert->cert_type = ntohs (dcert.cert_type); | ||
552 | cert->cert_tag = ntohs (dcert.cert_tag); | ||
553 | cert->algorithm = dcert.algorithm; | ||
554 | cert->certificate_size = udp_payload_length - (*off); | ||
555 | cert->certificate_data = GNUNET_malloc (cert->certificate_size); | ||
556 | GNUNET_memcpy (cert->certificate_data, | ||
557 | &udp_payload[*off], | ||
558 | cert->certificate_size); | ||
559 | (*off) += cert->certificate_size; | ||
560 | return cert; | ||
561 | } | ||
562 | |||
563 | |||
564 | /** | ||
565 | * Parse a DNS record entry. | ||
566 | * | ||
567 | * @param udp_payload entire UDP payload | ||
568 | * @param udp_payload_length length of @a udp_payload | ||
569 | * @param off pointer to the offset of the record to parse in the udp_payload (to be | ||
570 | * incremented by the size of the record) | ||
571 | * @param r where to write the record information | ||
572 | * @return #GNUNET_OK on success, #GNUNET_SYSERR if the record is malformed | ||
573 | */ | ||
574 | int | ||
575 | GNUNET_DNSPARSER_parse_record (const char *udp_payload, | ||
576 | size_t udp_payload_length, | ||
577 | size_t *off, | ||
578 | struct GNUNET_DNSPARSER_Record *r) | ||
579 | { | ||
580 | char *name; | ||
581 | struct GNUNET_TUN_DnsRecordLine rl; | ||
582 | size_t old_off; | ||
583 | uint16_t data_len; | ||
584 | |||
585 | name = GNUNET_DNSPARSER_parse_name (udp_payload, | ||
586 | udp_payload_length, | ||
587 | off); | ||
588 | if (NULL == name) | ||
589 | { | ||
590 | GNUNET_break_op (0); | ||
591 | return GNUNET_SYSERR; | ||
592 | } | ||
593 | r->name = name; | ||
594 | if (*off + sizeof (struct GNUNET_TUN_DnsRecordLine) > udp_payload_length) | ||
595 | { | ||
596 | GNUNET_break_op (0); | ||
597 | return GNUNET_SYSERR; | ||
598 | } | ||
599 | GNUNET_memcpy (&rl, &udp_payload[*off], sizeof (rl)); | ||
600 | (*off) += sizeof (rl); | ||
601 | r->type = ntohs (rl.type); | ||
602 | r->dns_traffic_class = ntohs (rl.dns_traffic_class); | ||
603 | r->expiration_time = GNUNET_TIME_relative_to_absolute (GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, | ||
604 | ntohl (rl.ttl))); | ||
605 | data_len = ntohs (rl.data_len); | ||
606 | if (*off + data_len > udp_payload_length) | ||
607 | { | ||
608 | GNUNET_break_op (0); | ||
609 | return GNUNET_SYSERR; | ||
610 | } | ||
611 | old_off = *off; | ||
612 | switch (r->type) | ||
613 | { | ||
614 | case GNUNET_DNSPARSER_TYPE_NS: | ||
615 | case GNUNET_DNSPARSER_TYPE_CNAME: | ||
616 | case GNUNET_DNSPARSER_TYPE_DNAME: | ||
617 | case GNUNET_DNSPARSER_TYPE_PTR: | ||
618 | r->data.hostname = GNUNET_DNSPARSER_parse_name (udp_payload, | ||
619 | udp_payload_length, | ||
620 | off); | ||
621 | if ( (NULL == r->data.hostname) || | ||
622 | (old_off + data_len != *off) ) | ||
623 | return GNUNET_SYSERR; | ||
624 | return GNUNET_OK; | ||
625 | case GNUNET_DNSPARSER_TYPE_SOA: | ||
626 | r->data.soa = GNUNET_DNSPARSER_parse_soa (udp_payload, | ||
627 | udp_payload_length, | ||
628 | off); | ||
629 | if ( (NULL == r->data.soa) || | ||
630 | (old_off + data_len != *off) ) | ||
631 | { | ||
632 | GNUNET_break_op (0); | ||
633 | return GNUNET_SYSERR; | ||
634 | } | ||
635 | return GNUNET_OK; | ||
636 | case GNUNET_DNSPARSER_TYPE_MX: | ||
637 | r->data.mx = GNUNET_DNSPARSER_parse_mx (udp_payload, | ||
638 | udp_payload_length, | ||
639 | off); | ||
640 | if ( (NULL == r->data.mx) || | ||
641 | (old_off + data_len != *off) ) | ||
642 | { | ||
643 | GNUNET_break_op (0); | ||
644 | return GNUNET_SYSERR; | ||
645 | } | ||
646 | return GNUNET_OK; | ||
647 | case GNUNET_DNSPARSER_TYPE_SRV: | ||
648 | r->data.srv = GNUNET_DNSPARSER_parse_srv (udp_payload, | ||
649 | udp_payload_length, | ||
650 | off); | ||
651 | if ( (NULL == r->data.srv) || | ||
652 | (old_off + data_len != *off) ) | ||
653 | { | ||
654 | GNUNET_break_op (0); | ||
655 | return GNUNET_SYSERR; | ||
656 | } | ||
657 | return GNUNET_OK; | ||
658 | default: | ||
659 | r->data.raw.data = GNUNET_malloc (data_len); | ||
660 | r->data.raw.data_len = data_len; | ||
661 | GNUNET_memcpy (r->data.raw.data, | ||
662 | &udp_payload[*off], | ||
663 | data_len); | ||
664 | break; | ||
665 | } | ||
666 | (*off) += data_len; | ||
667 | return GNUNET_OK; | ||
668 | } | ||
669 | |||
670 | |||
671 | /** | ||
672 | * Parse a UDP payload of a DNS packet in to a nice struct for further | ||
673 | * processing and manipulation. | ||
674 | * | ||
675 | * @param udp_payload wire-format of the DNS packet | ||
676 | * @param udp_payload_length number of bytes in @a udp_payload | ||
677 | * @return NULL on error, otherwise the parsed packet | ||
678 | */ | ||
679 | struct GNUNET_DNSPARSER_Packet * | ||
680 | GNUNET_DNSPARSER_parse (const char *udp_payload, | ||
681 | size_t udp_payload_length) | ||
682 | { | ||
683 | struct GNUNET_DNSPARSER_Packet *p; | ||
684 | const struct GNUNET_TUN_DnsHeader *dns; | ||
685 | size_t off; | ||
686 | unsigned int n; | ||
687 | |||
688 | if (udp_payload_length < sizeof (struct GNUNET_TUN_DnsHeader)) | ||
689 | return NULL; | ||
690 | dns = (const struct GNUNET_TUN_DnsHeader *) udp_payload; | ||
691 | off = sizeof (struct GNUNET_TUN_DnsHeader); | ||
692 | p = GNUNET_new (struct GNUNET_DNSPARSER_Packet); | ||
693 | p->flags = dns->flags; | ||
694 | p->id = dns->id; | ||
695 | n = ntohs (dns->query_count); | ||
696 | if (n > 0) | ||
697 | { | ||
698 | p->queries = GNUNET_new_array (n, | ||
699 | struct GNUNET_DNSPARSER_Query); | ||
700 | p->num_queries = n; | ||
701 | for (unsigned int i=0;i<n;i++) | ||
702 | if (GNUNET_OK != | ||
703 | GNUNET_DNSPARSER_parse_query (udp_payload, | ||
704 | udp_payload_length, | ||
705 | &off, | ||
706 | &p->queries[i])) | ||
707 | goto error; | ||
708 | } | ||
709 | n = ntohs (dns->answer_rcount); | ||
710 | if (n > 0) | ||
711 | { | ||
712 | p->answers = GNUNET_new_array (n, | ||
713 | struct GNUNET_DNSPARSER_Record); | ||
714 | p->num_answers = n; | ||
715 | for (unsigned int i=0;i<n;i++) | ||
716 | if (GNUNET_OK != | ||
717 | GNUNET_DNSPARSER_parse_record (udp_payload, | ||
718 | udp_payload_length, | ||
719 | &off, | ||
720 | &p->answers[i])) | ||
721 | goto error; | ||
722 | } | ||
723 | n = ntohs (dns->authority_rcount); | ||
724 | if (n > 0) | ||
725 | { | ||
726 | p->authority_records = GNUNET_new_array (n, | ||
727 | struct GNUNET_DNSPARSER_Record); | ||
728 | p->num_authority_records = n; | ||
729 | for (unsigned int i=0;i<n;i++) | ||
730 | if (GNUNET_OK != | ||
731 | GNUNET_DNSPARSER_parse_record (udp_payload, | ||
732 | udp_payload_length, | ||
733 | &off, | ||
734 | &p->authority_records[i])) | ||
735 | goto error; | ||
736 | } | ||
737 | n = ntohs (dns->additional_rcount); | ||
738 | if (n > 0) | ||
739 | { | ||
740 | p->additional_records = GNUNET_new_array (n, | ||
741 | struct GNUNET_DNSPARSER_Record); | ||
742 | p->num_additional_records = n; | ||
743 | for (unsigned int i=0;i<n;i++) | ||
744 | { | ||
745 | if (GNUNET_OK != | ||
746 | GNUNET_DNSPARSER_parse_record (udp_payload, | ||
747 | udp_payload_length, | ||
748 | &off, | ||
749 | &p->additional_records[i])) | ||
750 | goto error; | ||
751 | } | ||
752 | } | ||
753 | return p; | ||
754 | error: | ||
755 | GNUNET_break_op (0); | ||
756 | GNUNET_DNSPARSER_free_packet (p); | ||
757 | return NULL; | ||
758 | } | ||
759 | |||
760 | |||
761 | /** | ||
762 | * Duplicate (deep-copy) the given DNS record | ||
763 | * | ||
764 | * @param r the record | ||
765 | * @return the newly allocated record | ||
766 | */ | ||
767 | struct GNUNET_DNSPARSER_Record * | ||
768 | GNUNET_DNSPARSER_duplicate_record (const struct GNUNET_DNSPARSER_Record *r) | ||
769 | { | ||
770 | struct GNUNET_DNSPARSER_Record *dup = GNUNET_memdup (r, sizeof (*r)); | ||
771 | |||
772 | dup->name = GNUNET_strdup (r->name); | ||
773 | switch (r->type) | ||
774 | { | ||
775 | case GNUNET_DNSPARSER_TYPE_NS: | ||
776 | case GNUNET_DNSPARSER_TYPE_CNAME: | ||
777 | case GNUNET_DNSPARSER_TYPE_PTR: | ||
778 | { | ||
779 | dup->data.hostname = GNUNET_strdup (r->data.hostname); | ||
780 | break; | ||
781 | } | ||
782 | case GNUNET_DNSPARSER_TYPE_SOA: | ||
783 | { | ||
784 | dup->data.soa = GNUNET_DNSPARSER_duplicate_soa_record (r->data.soa); | ||
785 | break; | ||
786 | } | ||
787 | case GNUNET_DNSPARSER_TYPE_CERT: | ||
788 | { | ||
789 | dup->data.cert = GNUNET_DNSPARSER_duplicate_cert_record (r->data.cert); | ||
790 | break; | ||
791 | } | ||
792 | case GNUNET_DNSPARSER_TYPE_MX: | ||
793 | { | ||
794 | dup->data.mx = GNUNET_DNSPARSER_duplicate_mx_record (r->data.mx); | ||
795 | break; | ||
796 | } | ||
797 | case GNUNET_DNSPARSER_TYPE_SRV: | ||
798 | { | ||
799 | dup->data.srv = GNUNET_DNSPARSER_duplicate_srv_record (r->data.srv); | ||
800 | break; | ||
801 | } | ||
802 | default: | ||
803 | { | ||
804 | dup->data.raw.data = GNUNET_memdup (r->data.raw.data, | ||
805 | r->data.raw.data_len); | ||
806 | } | ||
807 | } | ||
808 | return dup; | ||
809 | } | ||
810 | |||
811 | |||
812 | /** | ||
813 | * Duplicate (deep-copy) the given DNS record | ||
814 | * | ||
815 | * @param r the record | ||
816 | * @return the newly allocated record | ||
817 | */ | ||
818 | struct GNUNET_DNSPARSER_SoaRecord * | ||
819 | GNUNET_DNSPARSER_duplicate_soa_record (const struct GNUNET_DNSPARSER_SoaRecord *r) | ||
820 | { | ||
821 | struct GNUNET_DNSPARSER_SoaRecord *dup = GNUNET_memdup (r, sizeof (*r)); | ||
822 | |||
823 | dup->mname = GNUNET_strdup (r->mname); | ||
824 | dup->rname = GNUNET_strdup (r->rname); | ||
825 | return dup; | ||
826 | } | ||
827 | |||
828 | |||
829 | /** | ||
830 | * Duplicate (deep-copy) the given DNS record | ||
831 | * | ||
832 | * @param r the record | ||
833 | * @return the newly allocated record | ||
834 | */ | ||
835 | struct GNUNET_DNSPARSER_CertRecord * | ||
836 | GNUNET_DNSPARSER_duplicate_cert_record (const struct GNUNET_DNSPARSER_CertRecord *r) | ||
837 | { | ||
838 | struct GNUNET_DNSPARSER_CertRecord *dup = GNUNET_memdup (r, sizeof (*r)); | ||
839 | |||
840 | dup->certificate_data = GNUNET_strdup (r->certificate_data); | ||
841 | return dup; | ||
842 | } | ||
843 | |||
844 | |||
845 | /** | ||
846 | * Duplicate (deep-copy) the given DNS record | ||
847 | * | ||
848 | * @param r the record | ||
849 | * @return the newly allocated record | ||
850 | */ | ||
851 | struct GNUNET_DNSPARSER_MxRecord * | ||
852 | GNUNET_DNSPARSER_duplicate_mx_record (const struct GNUNET_DNSPARSER_MxRecord *r) | ||
853 | { | ||
854 | struct GNUNET_DNSPARSER_MxRecord *dup = GNUNET_memdup (r, sizeof (*r)); | ||
855 | |||
856 | dup->mxhost = GNUNET_strdup (r->mxhost); | ||
857 | return dup; | ||
858 | } | ||
859 | |||
860 | |||
861 | /** | ||
862 | * Duplicate (deep-copy) the given DNS record | ||
863 | * | ||
864 | * @param r the record | ||
865 | * @return the newly allocated record | ||
866 | */ | ||
867 | struct GNUNET_DNSPARSER_SrvRecord * | ||
868 | GNUNET_DNSPARSER_duplicate_srv_record (const struct GNUNET_DNSPARSER_SrvRecord *r) | ||
869 | { | ||
870 | struct GNUNET_DNSPARSER_SrvRecord *dup = GNUNET_memdup (r, sizeof (*r)); | ||
871 | |||
872 | dup->target = GNUNET_strdup (r->target); | ||
873 | return dup; | ||
874 | } | ||
875 | |||
876 | |||
877 | /** | ||
878 | * Free memory taken by a packet. | ||
879 | * | ||
880 | * @param p packet to free | ||
881 | */ | ||
882 | void | ||
883 | GNUNET_DNSPARSER_free_packet (struct GNUNET_DNSPARSER_Packet *p) | ||
884 | { | ||
885 | for (unsigned int i=0;i<p->num_queries;i++) | ||
886 | GNUNET_free_non_null (p->queries[i].name); | ||
887 | GNUNET_free_non_null (p->queries); | ||
888 | for (unsigned int i=0;i<p->num_answers;i++) | ||
889 | GNUNET_DNSPARSER_free_record (&p->answers[i]); | ||
890 | GNUNET_free_non_null (p->answers); | ||
891 | for (unsigned int i=0;i<p->num_authority_records;i++) | ||
892 | GNUNET_DNSPARSER_free_record (&p->authority_records[i]); | ||
893 | GNUNET_free_non_null (p->authority_records); | ||
894 | for (unsigned int i=0;i<p->num_additional_records;i++) | ||
895 | GNUNET_DNSPARSER_free_record (&p->additional_records[i]); | ||
896 | GNUNET_free_non_null (p->additional_records); | ||
897 | GNUNET_free (p); | ||
898 | } | ||
899 | |||
900 | |||
901 | /* ********************** DNS packet assembly code **************** */ | ||
902 | |||
903 | |||
904 | /** | ||
905 | * Add a DNS name to the UDP packet at the given location, converting | ||
906 | * the name to IDNA notation as necessary. | ||
907 | * | ||
908 | * @param dst where to write the name (UDP packet) | ||
909 | * @param dst_len number of bytes in @a dst | ||
910 | * @param off pointer to offset where to write the name (increment by bytes used) | ||
911 | * must not be changed if there is an error | ||
912 | * @param name name to write | ||
913 | * @return #GNUNET_SYSERR if @a name is invalid | ||
914 | * #GNUNET_NO if @a name did not fit | ||
915 | * #GNUNET_OK if @a name was added to @a dst | ||
916 | */ | ||
917 | int | ||
918 | GNUNET_DNSPARSER_builder_add_name (char *dst, | ||
919 | size_t dst_len, | ||
920 | size_t *off, | ||
921 | const char *name) | ||
922 | { | ||
923 | const char *dot; | ||
924 | const char *idna_name; | ||
925 | char *idna_start; | ||
926 | size_t start; | ||
927 | size_t pos; | ||
928 | size_t len; | ||
929 | Idna_rc rc; | ||
930 | |||
931 | if (NULL == name) | ||
932 | return GNUNET_SYSERR; | ||
933 | |||
934 | if (IDNA_SUCCESS != | ||
935 | (rc = idna_to_ascii_8z (name, | ||
936 | &idna_start, | ||
937 | IDNA_ALLOW_UNASSIGNED))) | ||
938 | { | ||
939 | GNUNET_log (GNUNET_ERROR_TYPE_WARNING, | ||
940 | _("Failed to convert UTF-8 name `%s' to DNS IDNA format: %s\n"), | ||
941 | name, | ||
942 | idna_strerror (rc)); | ||
943 | return GNUNET_NO; | ||
944 | } | ||
945 | idna_name = idna_start; | ||
946 | start = *off; | ||
947 | if (start + strlen (idna_name) + 2 > dst_len) | ||
948 | goto fail; | ||
949 | pos = start; | ||
950 | do | ||
951 | { | ||
952 | dot = strchr (idna_name, '.'); | ||
953 | if (NULL == dot) | ||
954 | len = strlen (idna_name); | ||
955 | else | ||
956 | len = dot - idna_name; | ||
957 | if ( (len >= 64) || (0 == len) ) | ||
958 | { | ||
959 | GNUNET_log (GNUNET_ERROR_TYPE_ERROR, | ||
960 | "Invalid DNS name `%s': label with %u characters encountered\n", | ||
961 | name, | ||
962 | (unsigned int) len); | ||
963 | goto fail; /* label too long or empty */ | ||
964 | } | ||
965 | dst[pos++] = (char) (uint8_t) len; | ||
966 | GNUNET_memcpy (&dst[pos], | ||
967 | idna_name, | ||
968 | len); | ||
969 | pos += len; | ||
970 | idna_name += len + 1; /* also skip dot */ | ||
971 | } | ||
972 | while (NULL != dot); | ||
973 | dst[pos++] = '\0'; /* terminator */ | ||
974 | *off = pos; | ||
975 | #if WINDOWS | ||
976 | idn_free (idna_start); | ||
977 | #else | ||
978 | free (idna_start); | ||
979 | #endif | ||
980 | return GNUNET_OK; | ||
981 | fail: | ||
982 | #if WINDOWS | ||
983 | idn_free (idna_start); | ||
984 | #else | ||
985 | free (idna_start); | ||
986 | #endif | ||
987 | return GNUNET_NO; | ||
988 | } | ||
989 | |||
990 | |||
991 | /** | ||
992 | * Add a DNS query to the UDP packet at the given location. | ||
993 | * | ||
994 | * @param dst where to write the query | ||
995 | * @param dst_len number of bytes in @a dst | ||
996 | * @param off pointer to offset where to write the query (increment by bytes used) | ||
997 | * must not be changed if there is an error | ||
998 | * @param query query to write | ||
999 | * @return #GNUNET_SYSERR if @a query is invalid | ||
1000 | * #GNUNET_NO if @a query did not fit | ||
1001 | * #GNUNET_OK if @a query was added to @a dst | ||
1002 | */ | ||
1003 | int | ||
1004 | GNUNET_DNSPARSER_builder_add_query (char *dst, | ||
1005 | size_t dst_len, | ||
1006 | size_t *off, | ||
1007 | const struct GNUNET_DNSPARSER_Query *query) | ||
1008 | { | ||
1009 | int ret; | ||
1010 | struct GNUNET_TUN_DnsQueryLine ql; | ||
1011 | |||
1012 | ret = GNUNET_DNSPARSER_builder_add_name (dst, dst_len - sizeof (struct GNUNET_TUN_DnsQueryLine), off, query->name); | ||
1013 | if (ret != GNUNET_OK) | ||
1014 | return ret; | ||
1015 | ql.type = htons (query->type); | ||
1016 | ql.dns_traffic_class = htons (query->dns_traffic_class); | ||
1017 | GNUNET_memcpy (&dst[*off], &ql, sizeof (ql)); | ||
1018 | (*off) += sizeof (ql); | ||
1019 | return GNUNET_OK; | ||
1020 | } | ||
1021 | |||
1022 | |||
1023 | /** | ||
1024 | * Add an MX record to the UDP packet at the given location. | ||
1025 | * | ||
1026 | * @param dst where to write the mx record | ||
1027 | * @param dst_len number of bytes in @a dst | ||
1028 | * @param off pointer to offset where to write the mx information (increment by bytes used); | ||
1029 | * can also change if there was an error | ||
1030 | * @param mx mx information to write | ||
1031 | * @return #GNUNET_SYSERR if @a mx is invalid | ||
1032 | * #GNUNET_NO if @a mx did not fit | ||
1033 | * #GNUNET_OK if @a mx was added to @a dst | ||
1034 | */ | ||
1035 | int | ||
1036 | GNUNET_DNSPARSER_builder_add_mx (char *dst, | ||
1037 | size_t dst_len, | ||
1038 | size_t *off, | ||
1039 | const struct GNUNET_DNSPARSER_MxRecord *mx) | ||
1040 | { | ||
1041 | uint16_t mxpref; | ||
1042 | |||
1043 | if (*off + sizeof (uint16_t) > dst_len) | ||
1044 | return GNUNET_NO; | ||
1045 | mxpref = htons (mx->preference); | ||
1046 | GNUNET_memcpy (&dst[*off], | ||
1047 | &mxpref, | ||
1048 | sizeof (mxpref)); | ||
1049 | (*off) += sizeof (mxpref); | ||
1050 | return GNUNET_DNSPARSER_builder_add_name (dst, | ||
1051 | dst_len, | ||
1052 | off, | ||
1053 | mx->mxhost); | ||
1054 | } | ||
1055 | |||
1056 | |||
1057 | /** | ||
1058 | * Add a CERT record to the UDP packet at the given location. | ||
1059 | * | ||
1060 | * @param dst where to write the CERT record | ||
1061 | * @param dst_len number of bytes in @a dst | ||
1062 | * @param off pointer to offset where to write the CERT information (increment by bytes used); | ||
1063 | * can also change if there was an error | ||
1064 | * @param cert CERT information to write | ||
1065 | * @return #GNUNET_SYSERR if @a cert is invalid | ||
1066 | * #GNUNET_NO if @a cert did not fit | ||
1067 | * #GNUNET_OK if @a cert was added to @a dst | ||
1068 | */ | ||
1069 | int | ||
1070 | GNUNET_DNSPARSER_builder_add_cert (char *dst, | ||
1071 | size_t dst_len, | ||
1072 | size_t *off, | ||
1073 | const struct GNUNET_DNSPARSER_CertRecord *cert) | ||
1074 | { | ||
1075 | struct GNUNET_TUN_DnsCertRecord dcert; | ||
1076 | |||
1077 | if ( (cert->cert_type > UINT16_MAX) || | ||
1078 | (cert->algorithm > UINT8_MAX) ) | ||
1079 | { | ||
1080 | GNUNET_break (0); | ||
1081 | return GNUNET_SYSERR; | ||
1082 | } | ||
1083 | if (*off + sizeof (struct GNUNET_TUN_DnsCertRecord) + cert->certificate_size > dst_len) | ||
1084 | return GNUNET_NO; | ||
1085 | dcert.cert_type = htons ((uint16_t) cert->cert_type); | ||
1086 | dcert.cert_tag = htons ((uint16_t) cert->cert_tag); | ||
1087 | dcert.algorithm = (uint8_t) cert->algorithm; | ||
1088 | GNUNET_memcpy (&dst[*off], &dcert, sizeof (dcert)); | ||
1089 | (*off) += sizeof (dcert); | ||
1090 | GNUNET_memcpy (&dst[*off], cert->certificate_data, cert->certificate_size); | ||
1091 | (*off) += cert->certificate_size; | ||
1092 | return GNUNET_OK; | ||
1093 | } | ||
1094 | |||
1095 | |||
1096 | /** | ||
1097 | * Add an SOA record to the UDP packet at the given location. | ||
1098 | * | ||
1099 | * @param dst where to write the SOA record | ||
1100 | * @param dst_len number of bytes in @a dst | ||
1101 | * @param off pointer to offset where to write the SOA information (increment by bytes used) | ||
1102 | * can also change if there was an error | ||
1103 | * @param soa SOA information to write | ||
1104 | * @return #GNUNET_SYSERR if @a soa is invalid | ||
1105 | * #GNUNET_NO if @a soa did not fit | ||
1106 | * #GNUNET_OK if @a soa was added to @a dst | ||
1107 | */ | ||
1108 | int | ||
1109 | GNUNET_DNSPARSER_builder_add_soa (char *dst, | ||
1110 | size_t dst_len, | ||
1111 | size_t *off, | ||
1112 | const struct GNUNET_DNSPARSER_SoaRecord *soa) | ||
1113 | { | ||
1114 | struct GNUNET_TUN_DnsSoaRecord sd; | ||
1115 | int ret; | ||
1116 | |||
1117 | if ( (GNUNET_OK != (ret = GNUNET_DNSPARSER_builder_add_name (dst, | ||
1118 | dst_len, | ||
1119 | off, | ||
1120 | soa->mname))) || | ||
1121 | (GNUNET_OK != (ret = GNUNET_DNSPARSER_builder_add_name (dst, | ||
1122 | dst_len, | ||
1123 | off, | ||
1124 | soa->rname)) ) ) | ||
1125 | return ret; | ||
1126 | if (*off + sizeof (struct GNUNET_TUN_DnsSoaRecord) > dst_len) | ||
1127 | return GNUNET_NO; | ||
1128 | sd.serial = htonl (soa->serial); | ||
1129 | sd.refresh = htonl (soa->refresh); | ||
1130 | sd.retry = htonl (soa->retry); | ||
1131 | sd.expire = htonl (soa->expire); | ||
1132 | sd.minimum = htonl (soa->minimum_ttl); | ||
1133 | GNUNET_memcpy (&dst[*off], &sd, sizeof (sd)); | ||
1134 | (*off) += sizeof (sd); | ||
1135 | return GNUNET_OK; | ||
1136 | } | ||
1137 | |||
1138 | |||
1139 | /** | ||
1140 | * Add an SRV record to the UDP packet at the given location. | ||
1141 | * | ||
1142 | * @param dst where to write the SRV record | ||
1143 | * @param dst_len number of bytes in @a dst | ||
1144 | * @param off pointer to offset where to write the SRV information (increment by bytes used) | ||
1145 | * can also change if there was an error | ||
1146 | * @param srv SRV information to write | ||
1147 | * @return #GNUNET_SYSERR if @a srv is invalid | ||
1148 | * #GNUNET_NO if @a srv did not fit | ||
1149 | * #GNUNET_OK if @a srv was added to @a dst | ||
1150 | */ | ||
1151 | int | ||
1152 | GNUNET_DNSPARSER_builder_add_srv (char *dst, | ||
1153 | size_t dst_len, | ||
1154 | size_t *off, | ||
1155 | const struct GNUNET_DNSPARSER_SrvRecord *srv) | ||
1156 | { | ||
1157 | struct GNUNET_TUN_DnsSrvRecord sd; | ||
1158 | int ret; | ||
1159 | |||
1160 | if (*off + sizeof (struct GNUNET_TUN_DnsSrvRecord) > dst_len) | ||
1161 | return GNUNET_NO; | ||
1162 | sd.prio = htons (srv->priority); | ||
1163 | sd.weight = htons (srv->weight); | ||
1164 | sd.port = htons (srv->port); | ||
1165 | GNUNET_memcpy (&dst[*off], | ||
1166 | &sd, | ||
1167 | sizeof (sd)); | ||
1168 | (*off) += sizeof (sd); | ||
1169 | if (GNUNET_OK != (ret = GNUNET_DNSPARSER_builder_add_name (dst, | ||
1170 | dst_len, | ||
1171 | off, | ||
1172 | srv->target))) | ||
1173 | return ret; | ||
1174 | return GNUNET_OK; | ||
1175 | } | ||
1176 | |||
1177 | |||
1178 | /** | ||
1179 | * Add a DNS record to the UDP packet at the given location. | ||
1180 | * | ||
1181 | * @param dst where to write the query | ||
1182 | * @param dst_len number of bytes in @a dst | ||
1183 | * @param off pointer to offset where to write the query (increment by bytes used) | ||
1184 | * must not be changed if there is an error | ||
1185 | * @param record record to write | ||
1186 | * @return #GNUNET_SYSERR if @a record is invalid | ||
1187 | * #GNUNET_NO if @a record did not fit | ||
1188 | * #GNUNET_OK if @a record was added to @a dst | ||
1189 | */ | ||
1190 | static int | ||
1191 | add_record (char *dst, | ||
1192 | size_t dst_len, | ||
1193 | size_t *off, | ||
1194 | const struct GNUNET_DNSPARSER_Record *record) | ||
1195 | { | ||
1196 | int ret; | ||
1197 | size_t start; | ||
1198 | size_t pos; | ||
1199 | struct GNUNET_TUN_DnsRecordLine rl; | ||
1200 | |||
1201 | start = *off; | ||
1202 | ret = GNUNET_DNSPARSER_builder_add_name (dst, | ||
1203 | dst_len - sizeof (struct GNUNET_TUN_DnsRecordLine), | ||
1204 | off, | ||
1205 | record->name); | ||
1206 | if (GNUNET_OK != ret) | ||
1207 | return ret; | ||
1208 | /* '*off' is now the position where we will need to write the record line */ | ||
1209 | |||
1210 | pos = *off + sizeof (struct GNUNET_TUN_DnsRecordLine); | ||
1211 | switch (record->type) | ||
1212 | { | ||
1213 | case GNUNET_DNSPARSER_TYPE_MX: | ||
1214 | ret = GNUNET_DNSPARSER_builder_add_mx (dst, | ||
1215 | dst_len, | ||
1216 | &pos, | ||
1217 | record->data.mx); | ||
1218 | break; | ||
1219 | case GNUNET_DNSPARSER_TYPE_CERT: | ||
1220 | ret = GNUNET_DNSPARSER_builder_add_cert (dst, | ||
1221 | dst_len, | ||
1222 | &pos, | ||
1223 | record->data.cert); | ||
1224 | break; | ||
1225 | case GNUNET_DNSPARSER_TYPE_SOA: | ||
1226 | ret = GNUNET_DNSPARSER_builder_add_soa (dst, | ||
1227 | dst_len, | ||
1228 | &pos, | ||
1229 | record->data.soa); | ||
1230 | break; | ||
1231 | case GNUNET_DNSPARSER_TYPE_NS: | ||
1232 | case GNUNET_DNSPARSER_TYPE_CNAME: | ||
1233 | case GNUNET_DNSPARSER_TYPE_PTR: | ||
1234 | ret = GNUNET_DNSPARSER_builder_add_name (dst, | ||
1235 | dst_len, | ||
1236 | &pos, | ||
1237 | record->data.hostname); | ||
1238 | break; | ||
1239 | case GNUNET_DNSPARSER_TYPE_SRV: | ||
1240 | ret = GNUNET_DNSPARSER_builder_add_srv (dst, | ||
1241 | dst_len, | ||
1242 | &pos, | ||
1243 | record->data.srv); | ||
1244 | break; | ||
1245 | default: | ||
1246 | if (pos + record->data.raw.data_len > dst_len) | ||
1247 | { | ||
1248 | ret = GNUNET_NO; | ||
1249 | break; | ||
1250 | } | ||
1251 | GNUNET_memcpy (&dst[pos], | ||
1252 | record->data.raw.data, | ||
1253 | record->data.raw.data_len); | ||
1254 | pos += record->data.raw.data_len; | ||
1255 | ret = GNUNET_OK; | ||
1256 | break; | ||
1257 | } | ||
1258 | if (GNUNET_OK != ret) | ||
1259 | { | ||
1260 | *off = start; | ||
1261 | return GNUNET_NO; | ||
1262 | } | ||
1263 | |||
1264 | if (pos - (*off + sizeof (struct GNUNET_TUN_DnsRecordLine)) > UINT16_MAX) | ||
1265 | { | ||
1266 | /* record data too long */ | ||
1267 | *off = start; | ||
1268 | return GNUNET_NO; | ||
1269 | } | ||
1270 | rl.type = htons (record->type); | ||
1271 | rl.dns_traffic_class = htons (record->dns_traffic_class); | ||
1272 | rl.ttl = htonl (GNUNET_TIME_absolute_get_remaining (record->expiration_time).rel_value_us / 1000LL / 1000LL); /* in seconds */ | ||
1273 | rl.data_len = htons ((uint16_t) (pos - (*off + sizeof (struct GNUNET_TUN_DnsRecordLine)))); | ||
1274 | GNUNET_memcpy (&dst[*off], | ||
1275 | &rl, | ||
1276 | sizeof (struct GNUNET_TUN_DnsRecordLine)); | ||
1277 | *off = pos; | ||
1278 | return GNUNET_OK; | ||
1279 | } | ||
1280 | |||
1281 | |||
1282 | /** | ||
1283 | * Given a DNS packet @a p, generate the corresponding UDP payload. | ||
1284 | * Note that we do not attempt to pack the strings with pointers | ||
1285 | * as this would complicate the code and this is about being | ||
1286 | * simple and secure, not fast, fancy and broken like bind. | ||
1287 | * | ||
1288 | * @param p packet to pack | ||
1289 | * @param max maximum allowed size for the resulting UDP payload | ||
1290 | * @param buf set to a buffer with the packed message | ||
1291 | * @param buf_length set to the length of @a buf | ||
1292 | * @return #GNUNET_SYSERR if @a p is invalid | ||
1293 | * #GNUNET_NO if @a p was truncated (but there is still a result in @a buf) | ||
1294 | * #GNUNET_OK if @a p was packed completely into @a buf | ||
1295 | */ | ||
1296 | int | ||
1297 | GNUNET_DNSPARSER_pack (const struct GNUNET_DNSPARSER_Packet *p, | ||
1298 | uint16_t max, | ||
1299 | char **buf, | ||
1300 | size_t *buf_length) | ||
1301 | { | ||
1302 | struct GNUNET_TUN_DnsHeader dns; | ||
1303 | size_t off; | ||
1304 | char tmp[max]; | ||
1305 | int ret; | ||
1306 | int trc; | ||
1307 | |||
1308 | if ( (p->num_queries > UINT16_MAX) || | ||
1309 | (p->num_answers > UINT16_MAX) || | ||
1310 | (p->num_authority_records > UINT16_MAX) || | ||
1311 | (p->num_additional_records > UINT16_MAX) ) | ||
1312 | return GNUNET_SYSERR; | ||
1313 | dns.id = p->id; | ||
1314 | dns.flags = p->flags; | ||
1315 | dns.query_count = htons (p->num_queries); | ||
1316 | dns.answer_rcount = htons (p->num_answers); | ||
1317 | dns.authority_rcount = htons (p->num_authority_records); | ||
1318 | dns.additional_rcount = htons (p->num_additional_records); | ||
1319 | |||
1320 | off = sizeof (struct GNUNET_TUN_DnsHeader); | ||
1321 | trc = GNUNET_NO; | ||
1322 | for (unsigned int i=0;i<p->num_queries;i++) | ||
1323 | { | ||
1324 | ret = GNUNET_DNSPARSER_builder_add_query (tmp, | ||
1325 | sizeof (tmp), | ||
1326 | &off, | ||
1327 | &p->queries[i]); | ||
1328 | if (GNUNET_SYSERR == ret) | ||
1329 | return GNUNET_SYSERR; | ||
1330 | if (GNUNET_NO == ret) | ||
1331 | { | ||
1332 | dns.query_count = htons ((uint16_t) (i-1)); | ||
1333 | trc = GNUNET_YES; | ||
1334 | break; | ||
1335 | } | ||
1336 | } | ||
1337 | for (unsigned int i=0;i<p->num_answers;i++) | ||
1338 | { | ||
1339 | ret = add_record (tmp, | ||
1340 | sizeof (tmp), | ||
1341 | &off, | ||
1342 | &p->answers[i]); | ||
1343 | if (GNUNET_SYSERR == ret) | ||
1344 | return GNUNET_SYSERR; | ||
1345 | if (GNUNET_NO == ret) | ||
1346 | { | ||
1347 | dns.answer_rcount = htons ((uint16_t) (i-1)); | ||
1348 | trc = GNUNET_YES; | ||
1349 | break; | ||
1350 | } | ||
1351 | } | ||
1352 | for (unsigned int i=0;i<p->num_authority_records;i++) | ||
1353 | { | ||
1354 | ret = add_record (tmp, | ||
1355 | sizeof (tmp), | ||
1356 | &off, | ||
1357 | &p->authority_records[i]); | ||
1358 | if (GNUNET_SYSERR == ret) | ||
1359 | return GNUNET_SYSERR; | ||
1360 | if (GNUNET_NO == ret) | ||
1361 | { | ||
1362 | dns.authority_rcount = htons ((uint16_t) (i-1)); | ||
1363 | trc = GNUNET_YES; | ||
1364 | break; | ||
1365 | } | ||
1366 | } | ||
1367 | for (unsigned int i=0;i<p->num_additional_records;i++) | ||
1368 | { | ||
1369 | ret = add_record (tmp, | ||
1370 | sizeof (tmp), | ||
1371 | &off, | ||
1372 | &p->additional_records[i]); | ||
1373 | if (GNUNET_SYSERR == ret) | ||
1374 | return GNUNET_SYSERR; | ||
1375 | if (GNUNET_NO == ret) | ||
1376 | { | ||
1377 | dns.additional_rcount = htons (i-1); | ||
1378 | trc = GNUNET_YES; | ||
1379 | break; | ||
1380 | } | ||
1381 | } | ||
1382 | |||
1383 | if (GNUNET_YES == trc) | ||
1384 | dns.flags.message_truncated = 1; | ||
1385 | GNUNET_memcpy (tmp, | ||
1386 | &dns, | ||
1387 | sizeof (struct GNUNET_TUN_DnsHeader)); | ||
1388 | |||
1389 | *buf = GNUNET_malloc (off); | ||
1390 | *buf_length = off; | ||
1391 | GNUNET_memcpy (*buf, | ||
1392 | tmp, | ||
1393 | off); | ||
1394 | if (GNUNET_YES == trc) | ||
1395 | return GNUNET_NO; | ||
1396 | return GNUNET_OK; | ||
1397 | } | ||
1398 | |||
1399 | |||
1400 | /** | ||
1401 | * Convert a block of binary data to HEX. | ||
1402 | * | ||
1403 | * @param data binary data to convert | ||
1404 | * @param data_size number of bytes in @a data | ||
1405 | * @return HEX string (lower case) | ||
1406 | */ | ||
1407 | char * | ||
1408 | GNUNET_DNSPARSER_bin_to_hex (const void *data, | ||
1409 | size_t data_size) | ||
1410 | { | ||
1411 | char *ret; | ||
1412 | size_t off; | ||
1413 | const uint8_t *idata; | ||
1414 | |||
1415 | idata = data; | ||
1416 | ret = GNUNET_malloc (data_size * 2 + 1); | ||
1417 | for (off = 0; off < data_size; off++) | ||
1418 | sprintf (&ret[off * 2], | ||
1419 | "%02x", | ||
1420 | idata[off]); | ||
1421 | return ret; | ||
1422 | } | ||
1423 | |||
1424 | |||
1425 | /** | ||
1426 | * Convert a HEX string to block of binary data. | ||
1427 | * | ||
1428 | * @param hex HEX string to convert (may contain mixed case) | ||
1429 | * @param data where to write result, must be | ||
1430 | * at least `strlen(hex)/2` bytes long | ||
1431 | * @return number of bytes written to data | ||
1432 | */ | ||
1433 | size_t | ||
1434 | GNUNET_DNSPARSER_hex_to_bin (const char *hex, | ||
1435 | void *data) | ||
1436 | { | ||
1437 | size_t data_size; | ||
1438 | size_t off; | ||
1439 | uint8_t *idata; | ||
1440 | unsigned int h; | ||
1441 | char in[3]; | ||
1442 | |||
1443 | data_size = strlen (hex) / 2; | ||
1444 | idata = data; | ||
1445 | in[2] = '\0'; | ||
1446 | for (off = 0; off < data_size; off++) | ||
1447 | { | ||
1448 | in[0] = tolower ((unsigned char) hex[off * 2]); | ||
1449 | in[1] = tolower ((unsigned char) hex[off * 2 + 1]); | ||
1450 | if (1 != sscanf (in, "%x", &h)) | ||
1451 | return off; | ||
1452 | idata[off] = (uint8_t) h; | ||
1453 | } | ||
1454 | return off; | ||
1455 | } | ||
1456 | |||
1457 | |||
1458 | /* end of dnsparser.c */ | ||