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322345fd LP |
1 | /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ |
2 | ||
3 | /*** | |
4 | This file is part of systemd. | |
5 | ||
6 | Copyright 2014 Lennart Poettering | |
7 | ||
8 | systemd is free software; you can redistribute it and/or modify it | |
9 | under the terms of the GNU Lesser General Public License as published by | |
10 | the Free Software Foundation; either version 2.1 of the License, or | |
11 | (at your option) any later version. | |
12 | ||
13 | systemd is distributed in the hope that it will be useful, but | |
14 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | Lesser General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU Lesser General Public License | |
19 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
20 | ***/ | |
21 | ||
22 | #include "resolved-dns-cache.h" | |
7e8e0422 | 23 | #include "resolved-dns-packet.h" |
322345fd | 24 | |
cbd4560e | 25 | /* Never cache more than 1K entries */ |
322345fd | 26 | #define CACHE_MAX 1024 |
cbd4560e LP |
27 | |
28 | /* We never keep any item longer than 10min in our cache */ | |
322345fd LP |
29 | #define CACHE_TTL_MAX_USEC (10 * USEC_PER_MINUTE) |
30 | ||
623a4c97 LP |
31 | typedef enum DnsCacheItemType DnsCacheItemType; |
32 | typedef struct DnsCacheItem DnsCacheItem; | |
33 | ||
34 | enum DnsCacheItemType { | |
35 | DNS_CACHE_POSITIVE, | |
36 | DNS_CACHE_NODATA, | |
37 | DNS_CACHE_NXDOMAIN, | |
38 | }; | |
39 | ||
40 | struct DnsCacheItem { | |
41 | DnsResourceKey *key; | |
42 | DnsResourceRecord *rr; | |
43 | usec_t until; | |
44 | DnsCacheItemType type; | |
45 | unsigned prioq_idx; | |
a4076574 LP |
46 | int owner_family; |
47 | union in_addr_union owner_address; | |
623a4c97 LP |
48 | LIST_FIELDS(DnsCacheItem, by_key); |
49 | }; | |
50 | ||
322345fd LP |
51 | static void dns_cache_item_free(DnsCacheItem *i) { |
52 | if (!i) | |
53 | return; | |
54 | ||
55 | dns_resource_record_unref(i->rr); | |
7e8e0422 | 56 | dns_resource_key_unref(i->key); |
322345fd LP |
57 | free(i); |
58 | } | |
59 | ||
60 | DEFINE_TRIVIAL_CLEANUP_FUNC(DnsCacheItem*, dns_cache_item_free); | |
61 | ||
62 | static void dns_cache_item_remove_and_free(DnsCache *c, DnsCacheItem *i) { | |
63 | DnsCacheItem *first; | |
64 | ||
65 | assert(c); | |
66 | ||
67 | if (!i) | |
68 | return; | |
69 | ||
7e8e0422 LP |
70 | first = hashmap_get(c->by_key, i->key); |
71 | LIST_REMOVE(by_key, first, i); | |
322345fd LP |
72 | |
73 | if (first) | |
7e8e0422 | 74 | assert_se(hashmap_replace(c->by_key, first->key, first) >= 0); |
322345fd | 75 | else |
7e8e0422 | 76 | hashmap_remove(c->by_key, i->key); |
322345fd | 77 | |
7e8e0422 | 78 | prioq_remove(c->by_expiry, i, &i->prioq_idx); |
322345fd LP |
79 | |
80 | dns_cache_item_free(i); | |
81 | } | |
82 | ||
83 | void dns_cache_flush(DnsCache *c) { | |
84 | DnsCacheItem *i; | |
85 | ||
86 | assert(c); | |
87 | ||
7e8e0422 | 88 | while ((i = hashmap_first(c->by_key))) |
322345fd LP |
89 | dns_cache_item_remove_and_free(c, i); |
90 | ||
7e8e0422 LP |
91 | assert(hashmap_size(c->by_key) == 0); |
92 | assert(prioq_size(c->by_expiry) == 0); | |
322345fd | 93 | |
7e8e0422 LP |
94 | hashmap_free(c->by_key); |
95 | c->by_key = NULL; | |
322345fd | 96 | |
7e8e0422 LP |
97 | prioq_free(c->by_expiry); |
98 | c->by_expiry = NULL; | |
322345fd LP |
99 | } |
100 | ||
7e8e0422 | 101 | static void dns_cache_remove(DnsCache *c, DnsResourceKey *key) { |
322345fd LP |
102 | DnsCacheItem *i; |
103 | ||
104 | assert(c); | |
105 | assert(key); | |
106 | ||
7e8e0422 | 107 | while ((i = hashmap_get(c->by_key, key))) |
322345fd LP |
108 | dns_cache_item_remove_and_free(c, i); |
109 | } | |
110 | ||
111 | static void dns_cache_make_space(DnsCache *c, unsigned add) { | |
112 | assert(c); | |
113 | ||
114 | if (add <= 0) | |
115 | return; | |
116 | ||
117 | /* Makes space for n new entries. Note that we actually allow | |
118 | * the cache to grow beyond CACHE_MAX, but only when we shall | |
119 | * add more RRs to the cache than CACHE_MAX at once. In that | |
120 | * case the cache will be emptied completely otherwise. */ | |
121 | ||
122 | for (;;) { | |
faa133f3 | 123 | _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL; |
322345fd LP |
124 | DnsCacheItem *i; |
125 | ||
7e8e0422 | 126 | if (prioq_size(c->by_expiry) <= 0) |
322345fd LP |
127 | break; |
128 | ||
7e8e0422 | 129 | if (prioq_size(c->by_expiry) + add < CACHE_MAX) |
322345fd LP |
130 | break; |
131 | ||
7e8e0422 | 132 | i = prioq_peek(c->by_expiry); |
cbd4560e LP |
133 | assert(i); |
134 | ||
faa133f3 | 135 | /* Take an extra reference to the key so that it |
cbd4560e | 136 | * doesn't go away in the middle of the remove call */ |
7e8e0422 | 137 | key = dns_resource_key_ref(i->key); |
faa133f3 | 138 | dns_cache_remove(c, key); |
322345fd LP |
139 | } |
140 | } | |
141 | ||
142 | void dns_cache_prune(DnsCache *c) { | |
143 | usec_t t = 0; | |
144 | ||
145 | assert(c); | |
146 | ||
147 | /* Remove all entries that are past their TTL */ | |
148 | ||
149 | for (;;) { | |
faa133f3 | 150 | _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL; |
322345fd | 151 | DnsCacheItem *i; |
322345fd | 152 | |
7e8e0422 | 153 | i = prioq_peek(c->by_expiry); |
322345fd LP |
154 | if (!i) |
155 | break; | |
156 | ||
322345fd | 157 | if (t <= 0) |
9a015429 | 158 | t = now(CLOCK_BOOTTIME); |
322345fd | 159 | |
7e8e0422 | 160 | if (i->until > t) |
322345fd LP |
161 | break; |
162 | ||
faa133f3 | 163 | /* Take an extra reference to the key so that it |
cbd4560e | 164 | * doesn't go away in the middle of the remove call */ |
7e8e0422 | 165 | key = dns_resource_key_ref(i->key); |
faa133f3 | 166 | dns_cache_remove(c, key); |
322345fd LP |
167 | } |
168 | } | |
169 | ||
170 | static int dns_cache_item_prioq_compare_func(const void *a, const void *b) { | |
322345fd LP |
171 | const DnsCacheItem *x = a, *y = b; |
172 | ||
7e8e0422 | 173 | if (x->until < y->until) |
322345fd | 174 | return -1; |
7e8e0422 | 175 | if (x->until > y->until) |
322345fd LP |
176 | return 1; |
177 | return 0; | |
178 | } | |
179 | ||
623a4c97 | 180 | static int dns_cache_init(DnsCache *c) { |
7e8e0422 LP |
181 | int r; |
182 | ||
623a4c97 LP |
183 | assert(c); |
184 | ||
7e8e0422 LP |
185 | r = prioq_ensure_allocated(&c->by_expiry, dns_cache_item_prioq_compare_func); |
186 | if (r < 0) | |
187 | return r; | |
188 | ||
d5099efc | 189 | r = hashmap_ensure_allocated(&c->by_key, &dns_resource_key_hash_ops); |
7e8e0422 LP |
190 | if (r < 0) |
191 | return r; | |
192 | ||
193 | return r; | |
194 | } | |
195 | ||
196 | static int dns_cache_link_item(DnsCache *c, DnsCacheItem *i) { | |
197 | DnsCacheItem *first; | |
198 | int r; | |
199 | ||
322345fd LP |
200 | assert(c); |
201 | assert(i); | |
322345fd | 202 | |
7e8e0422 LP |
203 | r = prioq_put(c->by_expiry, i, &i->prioq_idx); |
204 | if (r < 0) | |
205 | return r; | |
322345fd | 206 | |
7e8e0422 LP |
207 | first = hashmap_get(c->by_key, i->key); |
208 | if (first) { | |
209 | LIST_PREPEND(by_key, first, i); | |
210 | assert_se(hashmap_replace(c->by_key, first->key, first) >= 0); | |
211 | } else { | |
212 | r = hashmap_put(c->by_key, i->key, i); | |
213 | if (r < 0) { | |
214 | prioq_remove(c->by_expiry, i, &i->prioq_idx); | |
215 | return r; | |
216 | } | |
322345fd LP |
217 | } |
218 | ||
7e8e0422 | 219 | return 0; |
322345fd LP |
220 | } |
221 | ||
faa133f3 LP |
222 | static DnsCacheItem* dns_cache_get(DnsCache *c, DnsResourceRecord *rr) { |
223 | DnsCacheItem *i; | |
224 | ||
225 | assert(c); | |
226 | assert(rr); | |
227 | ||
7e8e0422 | 228 | LIST_FOREACH(by_key, i, hashmap_get(c->by_key, rr->key)) |
3ef77d04 | 229 | if (i->rr && dns_resource_record_equal(i->rr, rr) > 0) |
faa133f3 LP |
230 | return i; |
231 | ||
232 | return NULL; | |
233 | } | |
234 | ||
7e8e0422 LP |
235 | static void dns_cache_item_update_positive(DnsCache *c, DnsCacheItem *i, DnsResourceRecord *rr, usec_t timestamp) { |
236 | assert(c); | |
237 | assert(i); | |
238 | assert(rr); | |
239 | ||
240 | i->type = DNS_CACHE_POSITIVE; | |
241 | ||
242 | if (!i->by_key_prev) { | |
243 | /* We are the first item in the list, we need to | |
244 | * update the key used in the hashmap */ | |
245 | ||
246 | assert_se(hashmap_replace(c->by_key, rr->key, i) >= 0); | |
247 | } | |
248 | ||
249 | dns_resource_record_ref(rr); | |
250 | dns_resource_record_unref(i->rr); | |
251 | i->rr = rr; | |
252 | ||
253 | dns_resource_key_unref(i->key); | |
254 | i->key = dns_resource_key_ref(rr->key); | |
255 | ||
256 | i->until = timestamp + MIN(rr->ttl * USEC_PER_SEC, CACHE_TTL_MAX_USEC); | |
257 | ||
258 | prioq_reshuffle(c->by_expiry, i, &i->prioq_idx); | |
259 | } | |
260 | ||
a4076574 LP |
261 | static int dns_cache_put_positive( |
262 | DnsCache *c, | |
263 | DnsResourceRecord *rr, | |
264 | usec_t timestamp, | |
265 | int owner_family, | |
266 | const union in_addr_union *owner_address) { | |
267 | ||
322345fd | 268 | _cleanup_(dns_cache_item_freep) DnsCacheItem *i = NULL; |
7e8e0422 | 269 | DnsCacheItem *existing; |
322345fd LP |
270 | int r; |
271 | ||
272 | assert(c); | |
273 | assert(rr); | |
a4076574 | 274 | assert(owner_address); |
322345fd LP |
275 | |
276 | /* New TTL is 0? Delete the entry... */ | |
277 | if (rr->ttl <= 0) { | |
faa133f3 | 278 | dns_cache_remove(c, rr->key); |
322345fd LP |
279 | return 0; |
280 | } | |
281 | ||
ddf16339 LP |
282 | if (rr->key->class == DNS_CLASS_ANY) |
283 | return 0; | |
284 | if (rr->key->type == DNS_TYPE_ANY) | |
285 | return 0; | |
286 | ||
322345fd LP |
287 | /* Entry exists already? Update TTL and timestamp */ |
288 | existing = dns_cache_get(c, rr); | |
289 | if (existing) { | |
7e8e0422 | 290 | dns_cache_item_update_positive(c, existing, rr, timestamp); |
322345fd LP |
291 | return 0; |
292 | } | |
293 | ||
294 | /* Otherwise, add the new RR */ | |
623a4c97 | 295 | r = dns_cache_init(c); |
322345fd LP |
296 | if (r < 0) |
297 | return r; | |
298 | ||
7e8e0422 LP |
299 | dns_cache_make_space(c, 1); |
300 | ||
301 | i = new0(DnsCacheItem, 1); | |
302 | if (!i) | |
303 | return -ENOMEM; | |
304 | ||
305 | i->type = DNS_CACHE_POSITIVE; | |
306 | i->key = dns_resource_key_ref(rr->key); | |
307 | i->rr = dns_resource_record_ref(rr); | |
308 | i->until = timestamp + MIN(i->rr->ttl * USEC_PER_SEC, CACHE_TTL_MAX_USEC); | |
309 | i->prioq_idx = PRIOQ_IDX_NULL; | |
a4076574 LP |
310 | i->owner_family = owner_family; |
311 | i->owner_address = *owner_address; | |
7e8e0422 LP |
312 | |
313 | r = dns_cache_link_item(c, i); | |
314 | if (r < 0) | |
315 | return r; | |
316 | ||
317 | i = NULL; | |
318 | return 0; | |
319 | } | |
320 | ||
a4076574 LP |
321 | static int dns_cache_put_negative( |
322 | DnsCache *c, | |
323 | DnsResourceKey *key, | |
324 | int rcode, | |
325 | usec_t timestamp, | |
326 | uint32_t soa_ttl, | |
327 | int owner_family, | |
328 | const union in_addr_union *owner_address) { | |
329 | ||
7e8e0422 LP |
330 | _cleanup_(dns_cache_item_freep) DnsCacheItem *i = NULL; |
331 | int r; | |
332 | ||
333 | assert(c); | |
334 | assert(key); | |
a4076574 | 335 | assert(owner_address); |
7e8e0422 LP |
336 | |
337 | dns_cache_remove(c, key); | |
338 | ||
ddf16339 LP |
339 | if (key->class == DNS_CLASS_ANY) |
340 | return 0; | |
341 | if (key->type == DNS_TYPE_ANY) | |
342 | return 0; | |
95dd6257 LP |
343 | if (soa_ttl <= 0) |
344 | return 0; | |
ddf16339 | 345 | |
7e8e0422 LP |
346 | if (!IN_SET(rcode, DNS_RCODE_SUCCESS, DNS_RCODE_NXDOMAIN)) |
347 | return 0; | |
348 | ||
623a4c97 | 349 | r = dns_cache_init(c); |
322345fd LP |
350 | if (r < 0) |
351 | return r; | |
352 | ||
353 | dns_cache_make_space(c, 1); | |
354 | ||
355 | i = new0(DnsCacheItem, 1); | |
356 | if (!i) | |
357 | return -ENOMEM; | |
358 | ||
7e8e0422 LP |
359 | i->type = rcode == DNS_RCODE_SUCCESS ? DNS_CACHE_NODATA : DNS_CACHE_NXDOMAIN; |
360 | i->key = dns_resource_key_ref(key); | |
361 | i->until = timestamp + MIN(soa_ttl * USEC_PER_SEC, CACHE_TTL_MAX_USEC); | |
362 | i->prioq_idx = PRIOQ_IDX_NULL; | |
a4076574 LP |
363 | i->owner_family = owner_family; |
364 | i->owner_address = *owner_address; | |
322345fd | 365 | |
7e8e0422 | 366 | r = dns_cache_link_item(c, i); |
322345fd LP |
367 | if (r < 0) |
368 | return r; | |
369 | ||
322345fd | 370 | i = NULL; |
322345fd LP |
371 | return 0; |
372 | } | |
373 | ||
a4076574 LP |
374 | int dns_cache_put( |
375 | DnsCache *c, | |
376 | DnsQuestion *q, | |
377 | int rcode, | |
378 | DnsAnswer *answer, | |
379 | unsigned max_rrs, | |
380 | usec_t timestamp, | |
381 | int owner_family, | |
382 | const union in_addr_union *owner_address) { | |
383 | ||
7e8e0422 | 384 | unsigned i; |
322345fd LP |
385 | int r; |
386 | ||
387 | assert(c); | |
0ec7c46e | 388 | assert(q); |
322345fd | 389 | |
7e8e0422 LP |
390 | /* First, delete all matching old RRs, so that we only keep |
391 | * complete by_key in place. */ | |
392 | for (i = 0; i < q->n_keys; i++) | |
393 | dns_cache_remove(c, q->keys[i]); | |
0ec7c46e LP |
394 | |
395 | if (!answer) | |
396 | return 0; | |
397 | ||
faa133f3 LP |
398 | for (i = 0; i < answer->n_rrs; i++) |
399 | dns_cache_remove(c, answer->rrs[i]->key); | |
322345fd | 400 | |
7e8e0422 LP |
401 | /* We only care for positive replies and NXDOMAINs, on all |
402 | * other replies we will simply flush the respective entries, | |
403 | * and that's it */ | |
404 | ||
405 | if (!IN_SET(rcode, DNS_RCODE_SUCCESS, DNS_RCODE_NXDOMAIN)) | |
406 | return 0; | |
407 | ||
408 | /* Make some space for our new entries */ | |
409 | dns_cache_make_space(c, answer->n_rrs + q->n_keys); | |
322345fd | 410 | |
7e8e0422 | 411 | if (timestamp <= 0) |
9a015429 | 412 | timestamp = now(CLOCK_BOOTTIME); |
322345fd | 413 | |
7e8e0422 | 414 | /* Second, add in positive entries for all contained RRs */ |
d2f47562 | 415 | for (i = 0; i < MIN(max_rrs, answer->n_rrs); i++) { |
a4076574 | 416 | r = dns_cache_put_positive(c, answer->rrs[i], timestamp, owner_family, owner_address); |
7e8e0422 LP |
417 | if (r < 0) |
418 | goto fail; | |
419 | } | |
420 | ||
421 | /* Third, add in negative entries for all keys with no RR */ | |
422 | for (i = 0; i < q->n_keys; i++) { | |
423 | DnsResourceRecord *soa = NULL; | |
424 | ||
425 | r = dns_answer_contains(answer, q->keys[i]); | |
426 | if (r < 0) | |
427 | goto fail; | |
428 | if (r > 0) | |
429 | continue; | |
430 | ||
431 | r = dns_answer_find_soa(answer, q->keys[i], &soa); | |
432 | if (r < 0) | |
433 | goto fail; | |
434 | if (r == 0) | |
435 | continue; | |
436 | ||
a4076574 | 437 | r = dns_cache_put_negative(c, q->keys[i], rcode, timestamp, MIN(soa->soa.minimum, soa->ttl), owner_family, owner_address); |
322345fd LP |
438 | if (r < 0) |
439 | goto fail; | |
322345fd LP |
440 | } |
441 | ||
442 | return 0; | |
443 | ||
444 | fail: | |
445 | /* Adding all RRs failed. Let's clean up what we already | |
446 | * added, just in case */ | |
447 | ||
7e8e0422 LP |
448 | for (i = 0; i < q->n_keys; i++) |
449 | dns_cache_remove(c, q->keys[i]); | |
450 | for (i = 0; i < answer->n_rrs; i++) | |
faa133f3 | 451 | dns_cache_remove(c, answer->rrs[i]->key); |
322345fd LP |
452 | |
453 | return r; | |
454 | } | |
455 | ||
7e8e0422 | 456 | int dns_cache_lookup(DnsCache *c, DnsQuestion *q, int *rcode, DnsAnswer **ret) { |
faa133f3 LP |
457 | _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL; |
458 | unsigned i, n = 0; | |
322345fd | 459 | int r; |
7e8e0422 | 460 | bool nxdomain = false; |
322345fd LP |
461 | |
462 | assert(c); | |
faa133f3 | 463 | assert(q); |
623a4c97 | 464 | assert(rcode); |
faa133f3 | 465 | assert(ret); |
322345fd | 466 | |
faa133f3 LP |
467 | if (q->n_keys <= 0) { |
468 | *ret = NULL; | |
7e8e0422 | 469 | *rcode = 0; |
322345fd LP |
470 | return 0; |
471 | } | |
472 | ||
faa133f3 | 473 | for (i = 0; i < q->n_keys; i++) { |
322345fd LP |
474 | DnsCacheItem *j; |
475 | ||
ddf16339 LP |
476 | if (q->keys[i]->type == DNS_TYPE_ANY || |
477 | q->keys[i]->class == DNS_CLASS_ANY) { | |
478 | /* If we have ANY lookups we simply refresh */ | |
479 | *ret = NULL; | |
480 | *rcode = 0; | |
481 | return 0; | |
482 | } | |
483 | ||
7e8e0422 | 484 | j = hashmap_get(c->by_key, q->keys[i]); |
322345fd | 485 | if (!j) { |
faa133f3 LP |
486 | /* If one question cannot be answered we need to refresh */ |
487 | *ret = NULL; | |
7e8e0422 | 488 | *rcode = 0; |
faa133f3 | 489 | return 0; |
322345fd LP |
490 | } |
491 | ||
7e8e0422 LP |
492 | LIST_FOREACH(by_key, j, j) { |
493 | if (j->rr) | |
494 | n++; | |
495 | else if (j->type == DNS_CACHE_NXDOMAIN) | |
496 | nxdomain = true; | |
497 | } | |
faa133f3 LP |
498 | } |
499 | ||
7e8e0422 LP |
500 | if (n <= 0) { |
501 | *ret = NULL; | |
502 | *rcode = nxdomain ? DNS_RCODE_NXDOMAIN : DNS_RCODE_SUCCESS; | |
503 | return 1; | |
504 | } | |
faa133f3 LP |
505 | |
506 | answer = dns_answer_new(n); | |
507 | if (!answer) | |
508 | return -ENOMEM; | |
322345fd | 509 | |
faa133f3 LP |
510 | for (i = 0; i < q->n_keys; i++) { |
511 | DnsCacheItem *j; | |
322345fd | 512 | |
7e8e0422 LP |
513 | j = hashmap_get(c->by_key, q->keys[i]); |
514 | LIST_FOREACH(by_key, j, j) { | |
515 | if (j->rr) { | |
516 | r = dns_answer_add(answer, j->rr); | |
517 | if (r < 0) | |
518 | return r; | |
519 | } | |
322345fd LP |
520 | } |
521 | } | |
522 | ||
faa133f3 | 523 | *ret = answer; |
7e8e0422 | 524 | *rcode = DNS_RCODE_SUCCESS; |
faa133f3 LP |
525 | answer = NULL; |
526 | ||
527 | return n; | |
322345fd | 528 | } |
a4076574 LP |
529 | |
530 | int dns_cache_check_conflicts(DnsCache *cache, DnsResourceRecord *rr, int owner_family, const union in_addr_union *owner_address) { | |
531 | DnsCacheItem *i, *first; | |
532 | bool same_owner = true; | |
533 | ||
534 | assert(cache); | |
535 | assert(rr); | |
536 | ||
537 | dns_cache_prune(cache); | |
538 | ||
539 | /* See if there's a cache entry for the same key. If there | |
540 | * isn't there's no conflict */ | |
541 | first = hashmap_get(cache->by_key, rr->key); | |
542 | if (!first) | |
543 | return 0; | |
544 | ||
545 | /* See if the RR key is owned by the same owner, if so, there | |
546 | * isn't a conflict either */ | |
547 | LIST_FOREACH(by_key, i, first) { | |
548 | if (i->owner_family != owner_family || | |
549 | !in_addr_equal(owner_family, &i->owner_address, owner_address)) { | |
550 | same_owner = false; | |
551 | break; | |
552 | } | |
553 | } | |
554 | if (same_owner) | |
555 | return 0; | |
556 | ||
557 | /* See if there's the exact same RR in the cache. If yes, then | |
558 | * there's no conflict. */ | |
559 | if (dns_cache_get(cache, rr)) | |
560 | return 0; | |
561 | ||
562 | /* There's a conflict */ | |
563 | return 1; | |
564 | } |