Commit | Line | Data |
---|---|---|
059ec3d9 PH |
1 | /************************************************* |
2 | * Exim - an Internet mail transport agent * | |
3 | *************************************************/ | |
4 | ||
5a66c31b | 5 | /* Copyright (c) University of Cambridge 1995 - 2014 */ |
059ec3d9 PH |
6 | /* See the file NOTICE for conditions of use and distribution. */ |
7 | ||
8 | /* Functions for interfacing with the DNS. */ | |
9 | ||
10 | #include "exim.h" | |
11 | ||
12 | ||
059ec3d9 | 13 | |
bef5a11f PH |
14 | /************************************************* |
15 | * Fake DNS resolver * | |
16 | *************************************************/ | |
17 | ||
18 | /* This function is called instead of res_search() when Exim is running in its | |
19 | test harness. It recognizes some special domain names, and uses them to force | |
433a2980 PH |
20 | failure and retry responses (optionally with a delay). Otherwise, it calls an |
21 | external utility that mocks-up a nameserver, if it can find the utility. | |
22 | If not, it passes its arguments on to res_search(). The fake nameserver may | |
23 | also return a code specifying that the name should be passed on. | |
bef5a11f PH |
24 | |
25 | Background: the original test suite required a real nameserver to carry the | |
e7726cbf PH |
26 | test zones, whereas the new test suit has the fake server for portability. This |
27 | code supports both. | |
bef5a11f PH |
28 | |
29 | Arguments: | |
e7726cbf | 30 | domain the domain name |
bef5a11f PH |
31 | type the DNS record type |
32 | answerptr where to put the answer | |
33 | size size of the answer area | |
34 | ||
35 | Returns: length of returned data, or -1 on error (h_errno set) | |
36 | */ | |
37 | ||
38 | static int | |
1dc92d5a | 39 | fakens_search(const uschar *domain, int type, uschar *answerptr, int size) |
bef5a11f | 40 | { |
e7726cbf | 41 | int len = Ustrlen(domain); |
433a2980 | 42 | int asize = size; /* Locally modified */ |
e7726cbf PH |
43 | uschar *endname; |
44 | uschar name[256]; | |
433a2980 PH |
45 | uschar utilname[256]; |
46 | uschar *aptr = answerptr; /* Locally modified */ | |
47 | struct stat statbuf; | |
48 | ||
49 | /* Remove terminating dot. */ | |
e7726cbf PH |
50 | |
51 | if (domain[len - 1] == '.') len--; | |
52 | Ustrncpy(name, domain, len); | |
53 | name[len] = 0; | |
54 | endname = name + len; | |
bef5a11f | 55 | |
433a2980 PH |
56 | /* This code, for forcing TRY_AGAIN and NO_RECOVERY, is here so that it works |
57 | for the old test suite that uses a real nameserver. When the old test suite is | |
58 | eventually abandoned, this code could be moved into the fakens utility. */ | |
59 | ||
bef5a11f PH |
60 | if (len >= 14 && Ustrcmp(endname - 14, "test.again.dns") == 0) |
61 | { | |
62 | int delay = Uatoi(name); /* digits at the start of the name */ | |
63 | DEBUG(D_dns) debug_printf("Return from DNS lookup of %s (%s) faked for testing\n", | |
64 | name, dns_text_type(type)); | |
65 | if (delay > 0) | |
66 | { | |
67 | DEBUG(D_dns) debug_printf("delaying %d seconds\n", delay); | |
68 | sleep(delay); | |
69 | } | |
70 | h_errno = TRY_AGAIN; | |
71 | return -1; | |
72 | } | |
73 | ||
74 | if (len >= 13 && Ustrcmp(endname - 13, "test.fail.dns") == 0) | |
75 | { | |
76 | DEBUG(D_dns) debug_printf("Return from DNS lookup of %s (%s) faked for testing\n", | |
77 | name, dns_text_type(type)); | |
78 | h_errno = NO_RECOVERY; | |
79 | return -1; | |
80 | } | |
81 | ||
433a2980 PH |
82 | /* Look for the fakens utility, and if it exists, call it. */ |
83 | ||
84 | (void)string_format(utilname, sizeof(utilname), "%s/../bin/fakens", | |
85 | spool_directory); | |
86 | ||
87 | if (stat(CS utilname, &statbuf) >= 0) | |
bef5a11f | 88 | { |
433a2980 PH |
89 | pid_t pid; |
90 | int infd, outfd, rc; | |
91 | uschar *argv[5]; | |
92 | ||
93 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) using fakens\n", | |
94 | name, dns_text_type(type)); | |
95 | ||
96 | argv[0] = utilname; | |
97 | argv[1] = spool_directory; | |
98 | argv[2] = name; | |
99 | argv[3] = dns_text_type(type); | |
100 | argv[4] = NULL; | |
101 | ||
102 | pid = child_open(argv, NULL, 0000, &infd, &outfd, FALSE); | |
103 | if (pid < 0) | |
104 | log_write(0, LOG_MAIN|LOG_PANIC_DIE, "failed to run fakens: %s", | |
105 | strerror(errno)); | |
106 | ||
107 | len = 0; | |
108 | rc = -1; | |
109 | while (asize > 0 && (rc = read(outfd, aptr, asize)) > 0) | |
110 | { | |
111 | len += rc; | |
112 | aptr += rc; /* Don't modify the actual arguments, because they */ | |
113 | asize -= rc; /* may need to be passed on to res_search(). */ | |
114 | } | |
bef5a11f | 115 | |
433a2980 PH |
116 | if (rc < 0) |
117 | log_write(0, LOG_MAIN|LOG_PANIC_DIE, "read from fakens failed: %s", | |
118 | strerror(errno)); | |
bef5a11f | 119 | |
433a2980 | 120 | switch(child_close(pid, 0)) |
bef5a11f | 121 | { |
433a2980 PH |
122 | case 0: return len; |
123 | case 1: h_errno = HOST_NOT_FOUND; return -1; | |
124 | case 2: h_errno = TRY_AGAIN; return -1; | |
125 | default: | |
126 | case 3: h_errno = NO_RECOVERY; return -1; | |
127 | case 4: h_errno = NO_DATA; return -1; | |
128 | case 5: /* Pass on to res_search() */ | |
129 | DEBUG(D_dns) debug_printf("fakens returned PASS_ON\n"); | |
bef5a11f PH |
130 | } |
131 | } | |
132 | ||
433a2980 | 133 | /* fakens utility not found, or it returned "pass on" */ |
bef5a11f | 134 | |
433a2980 | 135 | DEBUG(D_dns) debug_printf("passing %s on to res_search()\n", domain); |
e7726cbf PH |
136 | |
137 | return res_search(CS domain, C_IN, type, answerptr, size); | |
bef5a11f PH |
138 | } |
139 | ||
140 | ||
059ec3d9 PH |
141 | |
142 | /************************************************* | |
143 | * Initialize and configure resolver * | |
144 | *************************************************/ | |
145 | ||
146 | /* Initialize the resolver and the storage for holding DNS answers if this is | |
147 | the first time we have been here, and set the resolver options. | |
148 | ||
149 | Arguments: | |
150 | qualify_single TRUE to set the RES_DEFNAMES option | |
151 | search_parents TRUE to set the RES_DNSRCH option | |
8c51eead | 152 | use_dnssec TRUE to set the RES_USE_DNSSEC option |
059ec3d9 PH |
153 | |
154 | Returns: nothing | |
155 | */ | |
156 | ||
157 | void | |
8c51eead | 158 | dns_init(BOOL qualify_single, BOOL search_parents, BOOL use_dnssec) |
059ec3d9 | 159 | { |
5bfb4cdf PP |
160 | res_state resp = os_get_dns_resolver_res(); |
161 | ||
162 | if ((resp->options & RES_INIT) == 0) | |
059ec3d9 | 163 | { |
5bfb4cdf PP |
164 | DEBUG(D_resolver) resp->options |= RES_DEBUG; /* For Cygwin */ |
165 | os_put_dns_resolver_res(resp); | |
059ec3d9 | 166 | res_init(); |
5bfb4cdf PP |
167 | DEBUG(D_resolver) resp->options |= RES_DEBUG; |
168 | os_put_dns_resolver_res(resp); | |
059ec3d9 PH |
169 | } |
170 | ||
5bfb4cdf PP |
171 | resp->options &= ~(RES_DNSRCH | RES_DEFNAMES); |
172 | resp->options |= (qualify_single? RES_DEFNAMES : 0) | | |
059ec3d9 | 173 | (search_parents? RES_DNSRCH : 0); |
5bfb4cdf PP |
174 | if (dns_retrans > 0) resp->retrans = dns_retrans; |
175 | if (dns_retry > 0) resp->retry = dns_retry; | |
e97d1f08 PP |
176 | |
177 | #ifdef RES_USE_EDNS0 | |
178 | if (dns_use_edns0 >= 0) | |
179 | { | |
180 | if (dns_use_edns0) | |
5bfb4cdf | 181 | resp->options |= RES_USE_EDNS0; |
e97d1f08 | 182 | else |
5bfb4cdf | 183 | resp->options &= ~RES_USE_EDNS0; |
e97d1f08 PP |
184 | DEBUG(D_resolver) |
185 | debug_printf("Coerced resolver EDNS0 support %s.\n", | |
186 | dns_use_edns0 ? "on" : "off"); | |
187 | } | |
188 | #else | |
189 | if (dns_use_edns0 >= 0) | |
190 | DEBUG(D_resolver) | |
191 | debug_printf("Unable to %sset EDNS0 without resolver support.\n", | |
192 | dns_use_edns0 ? "" : "un"); | |
193 | #endif | |
5bfb4cdf | 194 | |
1f4a55da PP |
195 | #ifndef DISABLE_DNSSEC |
196 | # ifdef RES_USE_DNSSEC | |
197 | # ifndef RES_USE_EDNS0 | |
198 | # error Have RES_USE_DNSSEC but not RES_USE_EDNS0? Something hinky ... | |
199 | # endif | |
8c51eead JH |
200 | if (use_dnssec) |
201 | resp->options |= RES_USE_DNSSEC; | |
0fbd9bff | 202 | if (dns_dnssec_ok >= 0) |
1f4a55da | 203 | { |
0fbd9bff | 204 | if (dns_use_edns0 == 0 && dns_dnssec_ok != 0) |
1f4a55da PP |
205 | { |
206 | DEBUG(D_resolver) | |
0fbd9bff | 207 | debug_printf("CONFLICT: dns_use_edns0 forced false, dns_dnssec_ok forced true, ignoring latter!\n"); |
1f4a55da PP |
208 | } |
209 | else | |
210 | { | |
0fbd9bff | 211 | if (dns_dnssec_ok) |
1f4a55da PP |
212 | resp->options |= RES_USE_DNSSEC; |
213 | else | |
214 | resp->options &= ~RES_USE_DNSSEC; | |
215 | DEBUG(D_resolver) debug_printf("Coerced resolver DNSSEC support %s.\n", | |
0fbd9bff | 216 | dns_dnssec_ok ? "on" : "off"); |
1f4a55da PP |
217 | } |
218 | } | |
219 | # else | |
0fbd9bff | 220 | if (dns_dnssec_ok >= 0) |
1f4a55da PP |
221 | DEBUG(D_resolver) |
222 | debug_printf("Unable to %sset DNSSEC without resolver support.\n", | |
0fbd9bff | 223 | dns_dnssec_ok ? "" : "un"); |
8c51eead JH |
224 | if (use_dnssec) |
225 | DEBUG(D_resolver) | |
93d4b03a | 226 | debug_printf("Unable to set DNSSEC without resolver support.\n"); |
1f4a55da PP |
227 | # endif |
228 | #endif /* DISABLE_DNSSEC */ | |
229 | ||
5bfb4cdf | 230 | os_put_dns_resolver_res(resp); |
059ec3d9 PH |
231 | } |
232 | ||
233 | ||
234 | ||
235 | /************************************************* | |
236 | * Build key name for PTR records * | |
237 | *************************************************/ | |
238 | ||
239 | /* This function inverts an IP address and adds the relevant domain, to produce | |
240 | a name that can be used to look up PTR records. | |
241 | ||
242 | Arguments: | |
243 | string the IP address as a string | |
244 | buffer a suitable buffer, long enough to hold the result | |
245 | ||
246 | Returns: nothing | |
247 | */ | |
248 | ||
249 | void | |
55414b25 | 250 | dns_build_reverse(const uschar *string, uschar *buffer) |
059ec3d9 | 251 | { |
55414b25 | 252 | const uschar *p = string + Ustrlen(string); |
059ec3d9 PH |
253 | uschar *pp = buffer; |
254 | ||
255 | /* Handle IPv4 address */ | |
256 | ||
257 | #if HAVE_IPV6 | |
258 | if (Ustrchr(string, ':') == NULL) | |
259 | #endif | |
260 | { | |
261 | int i; | |
262 | for (i = 0; i < 4; i++) | |
263 | { | |
55414b25 | 264 | const uschar *ppp = p; |
059ec3d9 PH |
265 | while (ppp > string && ppp[-1] != '.') ppp--; |
266 | Ustrncpy(pp, ppp, p - ppp); | |
267 | pp += p - ppp; | |
268 | *pp++ = '.'; | |
269 | p = ppp - 1; | |
270 | } | |
271 | Ustrcpy(pp, "in-addr.arpa"); | |
272 | } | |
273 | ||
274 | /* Handle IPv6 address; convert to binary so as to fill out any | |
275 | abbreviation in the textual form. */ | |
276 | ||
277 | #if HAVE_IPV6 | |
278 | else | |
279 | { | |
280 | int i; | |
281 | int v6[4]; | |
282 | (void)host_aton(string, v6); | |
283 | ||
284 | /* The original specification for IPv6 reverse lookup was to invert each | |
285 | nibble, and look in the ip6.int domain. The domain was subsequently | |
286 | changed to ip6.arpa. */ | |
287 | ||
288 | for (i = 3; i >= 0; i--) | |
289 | { | |
290 | int j; | |
291 | for (j = 0; j < 32; j += 4) | |
292 | { | |
293 | sprintf(CS pp, "%x.", (v6[i] >> j) & 15); | |
294 | pp += 2; | |
295 | } | |
296 | } | |
297 | Ustrcpy(pp, "ip6.arpa."); | |
298 | ||
299 | /* Another way of doing IPv6 reverse lookups was proposed in conjunction | |
300 | with A6 records. However, it fell out of favour when they did. The | |
301 | alternative was to construct a binary key, and look in ip6.arpa. I tried | |
302 | to make this code do that, but I could not make it work on Solaris 8. The | |
303 | resolver seems to lose the initial backslash somehow. However, now that | |
304 | this style of reverse lookup has been dropped, it doesn't matter. These | |
305 | lines are left here purely for historical interest. */ | |
306 | ||
307 | /************************************************** | |
308 | Ustrcpy(pp, "\\[x"); | |
309 | pp += 3; | |
310 | ||
311 | for (i = 0; i < 4; i++) | |
312 | { | |
313 | sprintf(pp, "%08X", v6[i]); | |
314 | pp += 8; | |
315 | } | |
316 | Ustrcpy(pp, "].ip6.arpa."); | |
317 | **************************************************/ | |
318 | ||
319 | } | |
320 | #endif | |
321 | } | |
322 | ||
323 | ||
324 | ||
325 | ||
326 | /************************************************* | |
327 | * Get next DNS record from answer block * | |
328 | *************************************************/ | |
329 | ||
330 | /* Call this with reset == RESET_ANSWERS to scan the answer block, reset == | |
e5a9dba6 PH |
331 | RESET_AUTHORITY to scan the authority records, reset == RESET_ADDITIONAL to |
332 | scan the additional records, and reset == RESET_NEXT to get the next record. | |
333 | The result is in static storage which must be copied if it is to be preserved. | |
059ec3d9 PH |
334 | |
335 | Arguments: | |
336 | dnsa pointer to dns answer block | |
337 | dnss pointer to dns scan block | |
338 | reset option specifing what portion to scan, as described above | |
339 | ||
340 | Returns: next dns record, or NULL when no more | |
341 | */ | |
342 | ||
343 | dns_record * | |
344 | dns_next_rr(dns_answer *dnsa, dns_scan *dnss, int reset) | |
345 | { | |
346 | HEADER *h = (HEADER *)dnsa->answer; | |
347 | int namelen; | |
348 | ||
349 | /* Reset the saved data when requested to, and skip to the first required RR */ | |
350 | ||
351 | if (reset != RESET_NEXT) | |
352 | { | |
353 | dnss->rrcount = ntohs(h->qdcount); | |
354 | dnss->aptr = dnsa->answer + sizeof(HEADER); | |
355 | ||
356 | /* Skip over questions; failure to expand the name just gives up */ | |
357 | ||
358 | while (dnss->rrcount-- > 0) | |
359 | { | |
360 | namelen = dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen, | |
361 | dnss->aptr, (DN_EXPAND_ARG4_TYPE) &(dnss->srr.name), DNS_MAXNAME); | |
362 | if (namelen < 0) { dnss->rrcount = 0; return NULL; } | |
363 | dnss->aptr += namelen + 4; /* skip name & type & class */ | |
364 | } | |
365 | ||
366 | /* Get the number of answer records. */ | |
367 | ||
368 | dnss->rrcount = ntohs(h->ancount); | |
369 | ||
e5a9dba6 PH |
370 | /* Skip over answers if we want to look at the authority section. Also skip |
371 | the NS records (i.e. authority section) if wanting to look at the additional | |
059ec3d9 PH |
372 | records. */ |
373 | ||
e5a9dba6 PH |
374 | if (reset == RESET_ADDITIONAL) dnss->rrcount += ntohs(h->nscount); |
375 | ||
376 | if (reset == RESET_AUTHORITY || reset == RESET_ADDITIONAL) | |
059ec3d9 | 377 | { |
059ec3d9 PH |
378 | while (dnss->rrcount-- > 0) |
379 | { | |
380 | namelen = dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen, | |
381 | dnss->aptr, (DN_EXPAND_ARG4_TYPE) &(dnss->srr.name), DNS_MAXNAME); | |
382 | if (namelen < 0) { dnss->rrcount = 0; return NULL; } | |
383 | dnss->aptr += namelen + 8; /* skip name, type, class & TTL */ | |
384 | GETSHORT(dnss->srr.size, dnss->aptr); /* size of data portion */ | |
385 | dnss->aptr += dnss->srr.size; /* skip over it */ | |
386 | } | |
e5a9dba6 PH |
387 | dnss->rrcount = (reset == RESET_AUTHORITY) |
388 | ? ntohs(h->nscount) : ntohs(h->arcount); | |
059ec3d9 PH |
389 | } |
390 | } | |
391 | ||
059ec3d9 PH |
392 | /* The variable dnss->aptr is now pointing at the next RR, and dnss->rrcount |
393 | contains the number of RR records left. */ | |
394 | ||
395 | if (dnss->rrcount-- <= 0) return NULL; | |
396 | ||
397 | /* If expanding the RR domain name fails, behave as if no more records | |
398 | (something safe). */ | |
399 | ||
400 | namelen = dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen, dnss->aptr, | |
401 | (DN_EXPAND_ARG4_TYPE) &(dnss->srr.name), DNS_MAXNAME); | |
402 | if (namelen < 0) { dnss->rrcount = 0; return NULL; } | |
403 | ||
404 | /* Move the pointer past the name and fill in the rest of the data structure | |
405 | from the following bytes. */ | |
406 | ||
407 | dnss->aptr += namelen; | |
408 | GETSHORT(dnss->srr.type, dnss->aptr); /* Record type */ | |
409 | dnss->aptr += 6; /* Don't want class or TTL */ | |
410 | GETSHORT(dnss->srr.size, dnss->aptr); /* Size of data portion */ | |
411 | dnss->srr.data = dnss->aptr; /* The record's data follows */ | |
412 | dnss->aptr += dnss->srr.size; /* Advance to next RR */ | |
413 | ||
414 | /* Return a pointer to the dns_record structure within the dns_answer. This is | |
415 | for convenience so that the scans can use nice-looking for loops. */ | |
416 | ||
417 | return &(dnss->srr); | |
418 | } | |
419 | ||
420 | ||
421 | ||
422 | ||
1f4a55da PP |
423 | /************************************************* |
424 | * Return whether AD bit set in DNS result * | |
425 | *************************************************/ | |
426 | ||
427 | /* We do not perform DNSSEC work ourselves; if the administrator has installed | |
428 | a verifying resolver which sets AD as appropriate, though, we'll use that. | |
429 | (AD = Authentic Data) | |
430 | ||
431 | Argument: pointer to dns answer block | |
432 | Returns: bool indicating presence of AD bit | |
433 | */ | |
434 | ||
435 | BOOL | |
4a142059 | 436 | dns_is_secure(const dns_answer * dnsa) |
1f4a55da PP |
437 | { |
438 | #ifdef DISABLE_DNSSEC | |
439 | DEBUG(D_dns) | |
440 | debug_printf("DNSSEC support disabled at build-time; dns_is_secure() false\n"); | |
441 | return FALSE; | |
442 | #else | |
443 | HEADER *h = (HEADER *)dnsa->answer; | |
444 | return h->ad ? TRUE : FALSE; | |
445 | #endif | |
446 | } | |
447 | ||
4a142059 JH |
448 | static void |
449 | dns_set_insecure(dns_answer * dnsa) | |
450 | { | |
451 | HEADER * h = (HEADER *)dnsa->answer; | |
452 | h->ad = 0; | |
453 | } | |
454 | ||
1f4a55da PP |
455 | |
456 | ||
457 | ||
059ec3d9 PH |
458 | /************************************************* |
459 | * Turn DNS type into text * | |
460 | *************************************************/ | |
461 | ||
885ccd3e PH |
462 | /* Turn the coded record type into a string for printing. All those that Exim |
463 | uses should be included here. | |
059ec3d9 PH |
464 | |
465 | Argument: record type | |
466 | Returns: pointer to string | |
467 | */ | |
468 | ||
469 | uschar * | |
470 | dns_text_type(int t) | |
471 | { | |
472 | switch(t) | |
473 | { | |
33397d19 PH |
474 | case T_A: return US"A"; |
475 | case T_MX: return US"MX"; | |
476 | case T_AAAA: return US"AAAA"; | |
477 | case T_A6: return US"A6"; | |
478 | case T_TXT: return US"TXT"; | |
eae0036b | 479 | case T_SPF: return US"SPF"; |
33397d19 | 480 | case T_PTR: return US"PTR"; |
885ccd3e | 481 | case T_SOA: return US"SOA"; |
33397d19 PH |
482 | case T_SRV: return US"SRV"; |
483 | case T_NS: return US"NS"; | |
8e669ac1 | 484 | case T_CNAME: return US"CNAME"; |
1e06383a | 485 | case T_TLSA: return US"TLSA"; |
33397d19 | 486 | default: return US"?"; |
059ec3d9 PH |
487 | } |
488 | } | |
489 | ||
490 | ||
491 | ||
492 | /************************************************* | |
493 | * Cache a failed DNS lookup result * | |
494 | *************************************************/ | |
495 | ||
496 | /* We cache failed lookup results so as not to experience timeouts many | |
497 | times for the same domain. We need to retain the resolver options because they | |
498 | may change. For successful lookups, we rely on resolver and/or name server | |
499 | caching. | |
500 | ||
501 | Arguments: | |
502 | name the domain name | |
503 | type the lookup type | |
504 | rc the return code | |
505 | ||
506 | Returns: the return code | |
507 | */ | |
508 | ||
509 | static int | |
1dc92d5a | 510 | dns_return(const uschar * name, int type, int rc) |
059ec3d9 | 511 | { |
5bfb4cdf | 512 | res_state resp = os_get_dns_resolver_res(); |
059ec3d9 PH |
513 | tree_node *node = store_get_perm(sizeof(tree_node) + 290); |
514 | sprintf(CS node->name, "%.255s-%s-%lx", name, dns_text_type(type), | |
5bfb4cdf | 515 | resp->options); |
059ec3d9 PH |
516 | node->data.val = rc; |
517 | (void)tree_insertnode(&tree_dns_fails, node); | |
518 | return rc; | |
519 | } | |
520 | ||
521 | ||
522 | ||
523 | /************************************************* | |
524 | * Do basic DNS lookup * | |
525 | *************************************************/ | |
526 | ||
527 | /* Call the resolver to look up the given domain name, using the given type, | |
528 | and check the result. The error code TRY_AGAIN is documented as meaning "non- | |
529 | Authoritive Host not found, or SERVERFAIL". Sometimes there are badly set | |
530 | up nameservers that produce this error continually, so there is the option of | |
531 | providing a list of domains for which this is treated as a non-existent | |
532 | host. | |
533 | ||
534 | Arguments: | |
535 | dnsa pointer to dns_answer structure | |
536 | name name to look up | |
537 | type type of DNS record required (T_A, T_MX, etc) | |
538 | ||
539 | Returns: DNS_SUCCEED successful lookup | |
540 | DNS_NOMATCH name not found (NXDOMAIN) | |
541 | or name contains illegal characters (if checking) | |
30e18802 | 542 | or name is an IP address (for IP address lookup) |
059ec3d9 PH |
543 | DNS_NODATA domain exists, but no data for this type (NODATA) |
544 | DNS_AGAIN soft failure, try again later | |
545 | DNS_FAIL DNS failure | |
546 | */ | |
547 | ||
548 | int | |
1dc92d5a | 549 | dns_basic_lookup(dns_answer *dnsa, const uschar *name, int type) |
059ec3d9 PH |
550 | { |
551 | #ifndef STAND_ALONE | |
7156b1ef | 552 | int rc = -1; |
55414b25 | 553 | const uschar *save_domain; |
059ec3d9 | 554 | #endif |
5bfb4cdf | 555 | res_state resp = os_get_dns_resolver_res(); |
059ec3d9 PH |
556 | |
557 | tree_node *previous; | |
558 | uschar node_name[290]; | |
559 | ||
560 | /* DNS lookup failures of any kind are cached in a tree. This is mainly so that | |
561 | a timeout on one domain doesn't happen time and time again for messages that | |
562 | have many addresses in the same domain. We rely on the resolver and name server | |
563 | caching for successful lookups. */ | |
564 | ||
565 | sprintf(CS node_name, "%.255s-%s-%lx", name, dns_text_type(type), | |
5bfb4cdf | 566 | resp->options); |
059ec3d9 PH |
567 | previous = tree_search(tree_dns_fails, node_name); |
568 | if (previous != NULL) | |
569 | { | |
570 | DEBUG(D_dns) debug_printf("DNS lookup of %.255s-%s: using cached value %s\n", | |
571 | name, dns_text_type(type), | |
572 | (previous->data.val == DNS_NOMATCH)? "DNS_NOMATCH" : | |
573 | (previous->data.val == DNS_NODATA)? "DNS_NODATA" : | |
574 | (previous->data.val == DNS_AGAIN)? "DNS_AGAIN" : | |
575 | (previous->data.val == DNS_FAIL)? "DNS_FAIL" : "??"); | |
576 | return previous->data.val; | |
577 | } | |
578 | ||
9d4319df JH |
579 | #ifdef EXPERIMENTAL_INTERNATIONAL |
580 | /* Convert all names to a-label form before doing lookup */ | |
581 | { | |
582 | uschar * alabel; | |
583 | uschar * errstr = NULL; | |
766e7a65 JH |
584 | DEBUG(D_dns) if (string_is_utf8(name)) |
585 | debug_printf("convert utf8 '%s' to alabel for for lookup\n", name); | |
9d4319df JH |
586 | if ((alabel = string_domain_utf8_to_alabel(name, &errstr)), errstr) |
587 | { | |
588 | DEBUG(D_dns) | |
37bf366e | 589 | debug_printf("DNS name '%s' utf8 conversion to alabel failed: %s\n", name, |
9d4319df JH |
590 | errstr); |
591 | host_find_failed_syntax = TRUE; | |
592 | return DNS_NOMATCH; | |
593 | } | |
594 | name = alabel; | |
595 | } | |
596 | #endif | |
597 | ||
059ec3d9 PH |
598 | /* If configured, check the hygene of the name passed to lookup. Otherwise, |
599 | although DNS lookups may give REFUSED at the lower level, some resolvers | |
600 | turn this into TRY_AGAIN, which is silly. Give a NOMATCH return, since such | |
601 | domains cannot be in the DNS. The check is now done by a regular expression; | |
602 | give it space for substring storage to save it having to get its own if the | |
603 | regex has substrings that are used - the default uses a conditional. | |
604 | ||
605 | This test is omitted for PTR records. These occur only in calls from the dnsdb | |
606 | lookup, which constructs the names itself, so they should be OK. Besides, | |
607 | bitstring labels don't conform to normal name syntax. (But the aren't used any | |
608 | more.) | |
609 | ||
610 | For SRV records, we omit the initial _smtp._tcp. components at the start. */ | |
611 | ||
612 | #ifndef STAND_ALONE /* Omit this for stand-alone tests */ | |
613 | ||
482d1455 | 614 | if (check_dns_names_pattern[0] != 0 && type != T_PTR && type != T_TXT) |
059ec3d9 | 615 | { |
1dc92d5a | 616 | const uschar *checkname = name; |
059ec3d9 PH |
617 | int ovector[3*(EXPAND_MAXN+1)]; |
618 | ||
476be7e2 | 619 | dns_pattern_init(); |
059ec3d9 PH |
620 | |
621 | /* For an SRV lookup, skip over the first two components (the service and | |
622 | protocol names, which both start with an underscore). */ | |
623 | ||
b4161d10 | 624 | if (type == T_SRV || type == T_TLSA) |
059ec3d9 PH |
625 | { |
626 | while (*checkname++ != '.'); | |
627 | while (*checkname++ != '.'); | |
628 | } | |
629 | ||
1dc92d5a | 630 | if (pcre_exec(regex_check_dns_names, NULL, CCS checkname, Ustrlen(checkname), |
059ec3d9 PH |
631 | 0, PCRE_EOPT, ovector, sizeof(ovector)/sizeof(int)) < 0) |
632 | { | |
633 | DEBUG(D_dns) | |
634 | debug_printf("DNS name syntax check failed: %s (%s)\n", name, | |
635 | dns_text_type(type)); | |
636 | host_find_failed_syntax = TRUE; | |
637 | return DNS_NOMATCH; | |
638 | } | |
639 | } | |
640 | ||
641 | #endif /* STAND_ALONE */ | |
642 | ||
643 | /* Call the resolver; for an overlong response, res_search() will return the | |
bef5a11f PH |
644 | number of bytes the message would need, so we need to check for this case. The |
645 | effect is to truncate overlong data. | |
646 | ||
30e18802 PH |
647 | On some systems, res_search() will recognize "A-for-A" queries and return |
648 | the IP address instead of returning -1 with h_error=HOST_NOT_FOUND. Some | |
649 | nameservers are also believed to do this. It is, of course, contrary to the | |
650 | specification of the DNS, so we lock it out. */ | |
651 | ||
cc00f4af | 652 | if ((type == T_A || type == T_AAAA) && string_is_ip_address(name, NULL) != 0) |
30e18802 PH |
653 | return DNS_NOMATCH; |
654 | ||
655 | /* If we are running in the test harness, instead of calling the normal resolver | |
bef5a11f PH |
656 | (res_search), we call fakens_search(), which recognizes certain special |
657 | domains, and interfaces to a fake nameserver for certain special zones. */ | |
658 | ||
cc00f4af JH |
659 | dnsa->answerlen = running_in_test_harness |
660 | ? fakens_search(name, type, dnsa->answer, MAXPACKET) | |
661 | : res_search(CCS name, C_IN, type, dnsa->answer, MAXPACKET); | |
059ec3d9 | 662 | |
80a47a2c TK |
663 | if (dnsa->answerlen > MAXPACKET) |
664 | { | |
665 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) resulted in overlong packet (size %d), truncating to %d.\n", | |
666 | name, dns_text_type(type), dnsa->answerlen, MAXPACKET); | |
667 | dnsa->answerlen = MAXPACKET; | |
668 | } | |
059ec3d9 PH |
669 | |
670 | if (dnsa->answerlen < 0) switch (h_errno) | |
671 | { | |
672 | case HOST_NOT_FOUND: | |
673 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave HOST_NOT_FOUND\n" | |
674 | "returning DNS_NOMATCH\n", name, dns_text_type(type)); | |
675 | return dns_return(name, type, DNS_NOMATCH); | |
676 | ||
677 | case TRY_AGAIN: | |
678 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave TRY_AGAIN\n", | |
679 | name, dns_text_type(type)); | |
680 | ||
681 | /* Cut this out for various test programs */ | |
1dc92d5a | 682 | #ifndef STAND_ALONE |
55414b25 | 683 | save_domain = deliver_domain; |
1dc92d5a | 684 | deliver_domain = string_copy(name); /* set $domain */ |
55414b25 | 685 | rc = match_isinlist(name, (const uschar **)&dns_again_means_nonexist, 0, NULL, NULL, |
059ec3d9 | 686 | MCL_DOMAIN, TRUE, NULL); |
55414b25 | 687 | deliver_domain = save_domain; |
059ec3d9 PH |
688 | if (rc != OK) |
689 | { | |
690 | DEBUG(D_dns) debug_printf("returning DNS_AGAIN\n"); | |
691 | return dns_return(name, type, DNS_AGAIN); | |
692 | } | |
693 | DEBUG(D_dns) debug_printf("%s is in dns_again_means_nonexist: returning " | |
694 | "DNS_NOMATCH\n", name); | |
695 | return dns_return(name, type, DNS_NOMATCH); | |
696 | ||
1dc92d5a | 697 | #else /* For stand-alone tests */ |
059ec3d9 | 698 | return dns_return(name, type, DNS_AGAIN); |
1dc92d5a | 699 | #endif |
059ec3d9 PH |
700 | |
701 | case NO_RECOVERY: | |
702 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave NO_RECOVERY\n" | |
703 | "returning DNS_FAIL\n", name, dns_text_type(type)); | |
704 | return dns_return(name, type, DNS_FAIL); | |
705 | ||
706 | case NO_DATA: | |
707 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave NO_DATA\n" | |
708 | "returning DNS_NODATA\n", name, dns_text_type(type)); | |
709 | return dns_return(name, type, DNS_NODATA); | |
710 | ||
711 | default: | |
712 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave unknown DNS error %d\n" | |
713 | "returning DNS_FAIL\n", name, dns_text_type(type), h_errno); | |
714 | return dns_return(name, type, DNS_FAIL); | |
715 | } | |
716 | ||
717 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) succeeded\n", | |
718 | name, dns_text_type(type)); | |
719 | ||
720 | return DNS_SUCCEED; | |
721 | } | |
722 | ||
723 | ||
724 | ||
725 | ||
726 | /************************************************ | |
727 | * Do a DNS lookup and handle CNAMES * | |
728 | ************************************************/ | |
729 | ||
730 | /* Look up the given domain name, using the given type. Follow CNAMEs if | |
731 | necessary, but only so many times. There aren't supposed to be CNAME chains in | |
732 | the DNS, but you are supposed to cope with them if you find them. | |
733 | ||
734 | The assumption is made that if the resolver gives back records of the | |
735 | requested type *and* a CNAME, we don't need to make another call to look up | |
736 | the CNAME. I can't see how it could return only some of the right records. If | |
737 | it's done a CNAME lookup in the past, it will have all of them; if not, it | |
738 | won't return any. | |
739 | ||
740 | If fully_qualified_name is not NULL, set it to point to the full name | |
741 | returned by the resolver, if this is different to what it is given, unless | |
742 | the returned name starts with "*" as some nameservers seem to be returning | |
766e7a65 JH |
743 | wildcards in this form. In international mode "different" means "alabel |
744 | forms are different". | |
059ec3d9 PH |
745 | |
746 | Arguments: | |
747 | dnsa pointer to dns_answer structure | |
748 | name domain name to look up | |
749 | type DNS record type (T_A, T_MX, etc) | |
750 | fully_qualified_name if not NULL, return the returned name here if its | |
751 | contents are different (i.e. it must be preset) | |
752 | ||
753 | Returns: DNS_SUCCEED successful lookup | |
754 | DNS_NOMATCH name not found | |
755 | DNS_NODATA no data found | |
756 | DNS_AGAIN soft failure, try again later | |
757 | DNS_FAIL DNS failure | |
758 | */ | |
759 | ||
760 | int | |
1dc92d5a | 761 | dns_lookup(dns_answer *dnsa, const uschar *name, int type, |
55414b25 | 762 | const uschar **fully_qualified_name) |
059ec3d9 PH |
763 | { |
764 | int i; | |
1dc92d5a | 765 | const uschar *orig_name = name; |
c85b3043 | 766 | BOOL secure_so_far = TRUE; |
059ec3d9 PH |
767 | |
768 | /* Loop to follow CNAME chains so far, but no further... */ | |
769 | ||
770 | for (i = 0; i < 10; i++) | |
771 | { | |
772 | uschar data[256]; | |
773 | dns_record *rr, cname_rr, type_rr; | |
774 | dns_scan dnss; | |
775 | int datalen, rc; | |
776 | ||
777 | /* DNS lookup failures get passed straight back. */ | |
778 | ||
779 | if ((rc = dns_basic_lookup(dnsa, name, type)) != DNS_SUCCEED) return rc; | |
780 | ||
781 | /* We should have either records of the required type, or a CNAME record, | |
782 | or both. We need to know whether both exist for getting the fully qualified | |
783 | name, but avoid scanning more than necessary. Note that we must copy the | |
784 | contents of any rr blocks returned by dns_next_rr() as they use the same | |
785 | area in the dnsa block. */ | |
786 | ||
787 | cname_rr.data = type_rr.data = NULL; | |
788 | for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); | |
789 | rr != NULL; | |
790 | rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)) | |
791 | { | |
792 | if (rr->type == type) | |
793 | { | |
794 | if (type_rr.data == NULL) type_rr = *rr; | |
795 | if (cname_rr.data != NULL) break; | |
796 | } | |
797 | else if (rr->type == T_CNAME) cname_rr = *rr; | |
798 | } | |
799 | ||
a2042e78 PH |
800 | /* For the first time round this loop, if a CNAME was found, take the fully |
801 | qualified name from it; otherwise from the first data record, if present. */ | |
059ec3d9 | 802 | |
a2042e78 | 803 | if (i == 0 && fully_qualified_name != NULL) |
059ec3d9 | 804 | { |
766e7a65 JH |
805 | uschar * rr_name = cname_rr.data ? cname_rr.name |
806 | : type_rr.data ? type_rr.name : NULL; | |
807 | if ( rr_name | |
808 | && Ustrcmp(rr_name, *fully_qualified_name) != 0 | |
809 | && rr_name[0] != '*' | |
810 | #ifdef EXPERIMENTAL_INTERNATIONAL | |
811 | && ( !string_is_utf8(*fully_qualified_name) | |
812 | || Ustrcmp(rr_name, | |
813 | string_domain_utf8_to_alabel(*fully_qualified_name, NULL)) != 0 | |
814 | ) | |
815 | #endif | |
816 | ) | |
817 | *fully_qualified_name = string_copy_dnsdomain(rr_name); | |
059ec3d9 PH |
818 | } |
819 | ||
820 | /* If any data records of the correct type were found, we are done. */ | |
821 | ||
c85b3043 JH |
822 | if (type_rr.data != NULL) |
823 | { | |
824 | if (!secure_so_far) /* mark insecure if any element of CNAME chain was */ | |
4a142059 | 825 | dns_set_insecure(dnsa); |
c85b3043 JH |
826 | return DNS_SUCCEED; |
827 | } | |
059ec3d9 PH |
828 | |
829 | /* If there are no data records, we need to re-scan the DNS using the | |
830 | domain given in the CNAME record, which should exist (otherwise we should | |
831 | have had a failure from dns_lookup). However code against the possibility of | |
832 | its not existing. */ | |
833 | ||
834 | if (cname_rr.data == NULL) return DNS_FAIL; | |
835 | datalen = dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen, | |
1dc92d5a | 836 | cname_rr.data, (DN_EXPAND_ARG4_TYPE)data, sizeof(data)); |
059ec3d9 PH |
837 | if (datalen < 0) return DNS_FAIL; |
838 | name = data; | |
a2042e78 | 839 | |
c85b3043 JH |
840 | if (!dns_is_secure(dnsa)) |
841 | secure_so_far = FALSE; | |
842 | ||
a2042e78 | 843 | DEBUG(D_dns) debug_printf("CNAME found: change to %s\n", name); |
059ec3d9 PH |
844 | } /* Loop back to do another lookup */ |
845 | ||
846 | /*Control reaches here after 10 times round the CNAME loop. Something isn't | |
847 | right... */ | |
848 | ||
849 | log_write(0, LOG_MAIN, "CNAME loop for %s encountered", orig_name); | |
850 | return DNS_FAIL; | |
851 | } | |
852 | ||
853 | ||
854 | ||
33397d19 PH |
855 | |
856 | ||
857 | ||
858 | /************************************************ | |
859 | * Do a DNS lookup and handle virtual types * | |
860 | ************************************************/ | |
861 | ||
8e669ac1 PH |
862 | /* This function handles some invented "lookup types" that synthesize feature |
863 | not available in the basic types. The special types all have negative values. | |
33397d19 PH |
864 | Positive type values are passed straight on to dns_lookup(). |
865 | ||
866 | Arguments: | |
867 | dnsa pointer to dns_answer structure | |
868 | name domain name to look up | |
869 | type DNS record type (T_A, T_MX, etc or a "special") | |
870 | fully_qualified_name if not NULL, return the returned name here if its | |
871 | contents are different (i.e. it must be preset) | |
872 | ||
873 | Returns: DNS_SUCCEED successful lookup | |
874 | DNS_NOMATCH name not found | |
875 | DNS_NODATA no data found | |
876 | DNS_AGAIN soft failure, try again later | |
877 | DNS_FAIL DNS failure | |
878 | */ | |
879 | ||
880 | int | |
1dc92d5a | 881 | dns_special_lookup(dns_answer *dnsa, const uschar *name, int type, |
55414b25 | 882 | const uschar **fully_qualified_name) |
33397d19 PH |
883 | { |
884 | if (type >= 0) return dns_lookup(dnsa, name, type, fully_qualified_name); | |
885 | ||
ea3bc19b PH |
886 | /* The "mx hosts only" type doesn't require any special action here */ |
887 | ||
888 | if (type == T_MXH) return dns_lookup(dnsa, name, T_MX, fully_qualified_name); | |
889 | ||
8e669ac1 | 890 | /* Find nameservers for the domain or the nearest enclosing zone, excluding the |
33397d19 PH |
891 | root servers. */ |
892 | ||
893 | if (type == T_ZNS) | |
894 | { | |
1dc92d5a | 895 | const uschar *d = name; |
33397d19 PH |
896 | while (d != 0) |
897 | { | |
898 | int rc = dns_lookup(dnsa, d, T_NS, fully_qualified_name); | |
899 | if (rc != DNS_NOMATCH && rc != DNS_NODATA) return rc; | |
900 | while (*d != 0 && *d != '.') d++; | |
8e669ac1 | 901 | if (*d++ == 0) break; |
33397d19 | 902 | } |
8e669ac1 PH |
903 | return DNS_NOMATCH; |
904 | } | |
33397d19 | 905 | |
e5a9dba6 PH |
906 | /* Try to look up the Client SMTP Authorization SRV record for the name. If |
907 | there isn't one, search from the top downwards for a CSA record in a parent | |
908 | domain, which might be making assertions about subdomains. If we find a record | |
909 | we set fully_qualified_name to whichever lookup succeeded, so that the caller | |
910 | can tell whether to look at the explicit authorization field or the subdomain | |
911 | assertion field. */ | |
912 | ||
913 | if (type == T_CSA) | |
914 | { | |
915 | uschar *srvname, *namesuff, *tld, *p; | |
916 | int priority, weight, port; | |
917 | int limit, rc, i; | |
918 | BOOL ipv6; | |
919 | dns_record *rr; | |
920 | dns_scan dnss; | |
921 | ||
922 | DEBUG(D_dns) debug_printf("CSA lookup of %s\n", name); | |
923 | ||
924 | srvname = string_sprintf("_client._smtp.%s", name); | |
925 | rc = dns_lookup(dnsa, srvname, T_SRV, NULL); | |
926 | if (rc == DNS_SUCCEED || rc == DNS_AGAIN) | |
927 | { | |
1dc92d5a | 928 | if (rc == DNS_SUCCEED) *fully_qualified_name = string_copy(name); |
e5a9dba6 PH |
929 | return rc; |
930 | } | |
931 | ||
932 | /* Search for CSA subdomain assertion SRV records from the top downwards, | |
933 | starting with the 2nd level domain. This order maximizes cache-friendliness. | |
934 | We skip the top level domains to avoid loading their nameservers and because | |
935 | we know they'll never have CSA SRV records. */ | |
936 | ||
937 | namesuff = Ustrrchr(name, '.'); | |
938 | if (namesuff == NULL) return DNS_NOMATCH; | |
939 | tld = namesuff + 1; | |
940 | ipv6 = FALSE; | |
941 | limit = dns_csa_search_limit; | |
942 | ||
943 | /* Use more appropriate search parameters if we are in the reverse DNS. */ | |
944 | ||
945 | if (strcmpic(namesuff, US".arpa") == 0) | |
946 | { | |
947 | if (namesuff - 8 > name && strcmpic(namesuff - 8, US".in-addr.arpa") == 0) | |
948 | { | |
949 | namesuff -= 8; | |
950 | tld = namesuff + 1; | |
951 | limit = 3; | |
952 | } | |
953 | else if (namesuff - 4 > name && strcmpic(namesuff - 4, US".ip6.arpa") == 0) | |
954 | { | |
955 | namesuff -= 4; | |
956 | tld = namesuff + 1; | |
957 | ipv6 = TRUE; | |
958 | limit = 3; | |
959 | } | |
960 | } | |
961 | ||
962 | DEBUG(D_dns) debug_printf("CSA TLD %s\n", tld); | |
963 | ||
964 | /* Do not perform the search if the top level or 2nd level domains do not | |
965 | exist. This is quite common, and when it occurs all the search queries would | |
966 | go to the root or TLD name servers, which is not friendly. So we check the | |
967 | AUTHORITY section; if it contains the root's SOA record or the TLD's SOA then | |
968 | the TLD or the 2LD (respectively) doesn't exist and we can skip the search. | |
969 | If the TLD and the 2LD exist but the explicit CSA record lookup failed, then | |
970 | the AUTHORITY SOA will be the 2LD's or a subdomain thereof. */ | |
971 | ||
972 | if (rc == DNS_NOMATCH) | |
973 | { | |
974 | /* This is really gross. The successful return value from res_search() is | |
975 | the packet length, which is stored in dnsa->answerlen. If we get a | |
976 | negative DNS reply then res_search() returns -1, which causes the bounds | |
977 | checks for name decompression to fail when it is treated as a packet | |
978 | length, which in turn causes the authority search to fail. The correct | |
979 | packet length has been lost inside libresolv, so we have to guess a | |
980 | replacement value. (The only way to fix this properly would be to | |
981 | re-implement res_search() and res_query() so that they don't muddle their | |
982 | success and packet length return values.) For added safety we only reset | |
983 | the packet length if the packet header looks plausible. */ | |
984 | ||
985 | HEADER *h = (HEADER *)dnsa->answer; | |
986 | if (h->qr == 1 && h->opcode == QUERY && h->tc == 0 | |
987 | && (h->rcode == NOERROR || h->rcode == NXDOMAIN) | |
988 | && ntohs(h->qdcount) == 1 && ntohs(h->ancount) == 0 | |
989 | && ntohs(h->nscount) >= 1) | |
990 | dnsa->answerlen = MAXPACKET; | |
991 | ||
992 | for (rr = dns_next_rr(dnsa, &dnss, RESET_AUTHORITY); | |
993 | rr != NULL; | |
994 | rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)) | |
995 | if (rr->type != T_SOA) continue; | |
996 | else if (strcmpic(rr->name, US"") == 0 || | |
997 | strcmpic(rr->name, tld) == 0) return DNS_NOMATCH; | |
998 | else break; | |
999 | } | |
1000 | ||
1001 | for (i = 0; i < limit; i++) | |
1002 | { | |
1003 | if (ipv6) | |
1004 | { | |
1005 | /* Scan through the IPv6 reverse DNS in chunks of 16 bits worth of IP | |
1006 | address, i.e. 4 hex chars and 4 dots, i.e. 8 chars. */ | |
1007 | namesuff -= 8; | |
1008 | if (namesuff <= name) return DNS_NOMATCH; | |
1009 | } | |
1010 | else | |
1011 | /* Find the start of the preceding domain name label. */ | |
1012 | do | |
1013 | if (--namesuff <= name) return DNS_NOMATCH; | |
1014 | while (*namesuff != '.'); | |
1015 | ||
1016 | DEBUG(D_dns) debug_printf("CSA parent search at %s\n", namesuff + 1); | |
1017 | ||
1018 | srvname = string_sprintf("_client._smtp.%s", namesuff + 1); | |
1019 | rc = dns_lookup(dnsa, srvname, T_SRV, NULL); | |
1020 | if (rc == DNS_AGAIN) return rc; | |
1021 | if (rc != DNS_SUCCEED) continue; | |
1022 | ||
1023 | /* Check that the SRV record we have found is worth returning. We don't | |
1024 | just return the first one we find, because some lower level SRV record | |
1025 | might make stricter assertions than its parent domain. */ | |
1026 | ||
1027 | for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); | |
1028 | rr != NULL; | |
1029 | rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)) | |
1030 | { | |
1031 | if (rr->type != T_SRV) continue; | |
1032 | ||
1033 | /* Extract the numerical SRV fields (p is incremented) */ | |
1034 | p = rr->data; | |
1035 | GETSHORT(priority, p); | |
4a142059 | 1036 | GETSHORT(weight, p); weight = weight; /* compiler quietening */ |
e5a9dba6 PH |
1037 | GETSHORT(port, p); |
1038 | ||
1039 | /* Check the CSA version number */ | |
1040 | if (priority != 1) continue; | |
1041 | ||
1042 | /* If it's making an interesting assertion, return this response. */ | |
1043 | if (port & 1) | |
1044 | { | |
1045 | *fully_qualified_name = namesuff + 1; | |
1046 | return DNS_SUCCEED; | |
1047 | } | |
1048 | } | |
1049 | } | |
1050 | return DNS_NOMATCH; | |
1051 | } | |
1052 | ||
33397d19 PH |
1053 | /* Control should never reach here */ |
1054 | ||
1055 | return DNS_FAIL; | |
1056 | } | |
1057 | ||
1058 | ||
1059 | ||
059ec3d9 PH |
1060 | |
1061 | ||
1062 | /************************************************* | |
1063 | * Get address(es) from DNS record * | |
1064 | *************************************************/ | |
1065 | ||
1066 | /* The record type is either T_A for an IPv4 address or T_AAAA (or T_A6 when | |
1067 | supported) for an IPv6 address. In the A6 case, there may be several addresses, | |
1068 | generated by following chains. A recursive function does all the hard work. A6 | |
1069 | records now look like passing into history, so the code is only included when | |
1070 | explicitly asked for. | |
1071 | ||
1072 | Argument: | |
1073 | dnsa the DNS answer block | |
1074 | rr the RR | |
1075 | ||
1076 | Returns: pointer a chain of dns_address items | |
1077 | */ | |
1078 | ||
1079 | dns_address * | |
1080 | dns_address_from_rr(dns_answer *dnsa, dns_record *rr) | |
1081 | { | |
1082 | dns_address *yield = NULL; | |
1083 | ||
059ec3d9 | 1084 | dnsa = dnsa; /* Stop picky compilers warning */ |
059ec3d9 PH |
1085 | |
1086 | if (rr->type == T_A) | |
1087 | { | |
1088 | uschar *p = (uschar *)(rr->data); | |
1089 | yield = store_get(sizeof(dns_address) + 20); | |
1090 | (void)sprintf(CS yield->address, "%d.%d.%d.%d", p[0], p[1], p[2], p[3]); | |
1091 | yield->next = NULL; | |
1092 | } | |
1093 | ||
1094 | #if HAVE_IPV6 | |
1095 | ||
059ec3d9 PH |
1096 | else |
1097 | { | |
1098 | yield = store_get(sizeof(dns_address) + 50); | |
1099 | inet_ntop(AF_INET6, (uschar *)(rr->data), CS yield->address, 50); | |
1100 | yield->next = NULL; | |
1101 | } | |
1102 | #endif /* HAVE_IPV6 */ | |
1103 | ||
1104 | return yield; | |
1105 | } | |
1106 | ||
476be7e2 JH |
1107 | |
1108 | ||
1109 | void | |
1110 | dns_pattern_init(void) | |
1111 | { | |
1112 | if (check_dns_names_pattern[0] != 0 && !regex_check_dns_names) | |
1113 | regex_check_dns_names = | |
1114 | regex_must_compile(check_dns_names_pattern, FALSE, TRUE); | |
1115 | } | |
1116 | ||
8c51eead JH |
1117 | /* vi: aw ai sw=2 |
1118 | */ | |
059ec3d9 | 1119 | /* End of dns.c */ |