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 | |
8e013028 | 26 | test zones, whereas the new test suite has the fake server for portability. This |
e7726cbf | 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 | ||
5f3d0983 HSHR |
84 | (void)string_format(utilname, sizeof(utilname), "%s/bin/fakens", |
85 | config_main_directory); | |
433a2980 PH |
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 | ||
5f3d0983 HSHR |
93 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) using fakens `%s'\n", |
94 | name, dns_text_type(type), utilname); | |
433a2980 PH |
95 | |
96 | argv[0] = utilname; | |
5f3d0983 | 97 | argv[1] = config_main_directory; |
433a2980 PH |
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 | } | |
8e013028 HSHR |
132 | else |
133 | { | |
134 | DEBUG(D_dns) debug_printf("fakens (%s) not found\n", utilname); | |
135 | } | |
bef5a11f | 136 | |
433a2980 | 137 | /* fakens utility not found, or it returned "pass on" */ |
bef5a11f | 138 | |
433a2980 | 139 | DEBUG(D_dns) debug_printf("passing %s on to res_search()\n", domain); |
e7726cbf PH |
140 | |
141 | return res_search(CS domain, C_IN, type, answerptr, size); | |
bef5a11f PH |
142 | } |
143 | ||
144 | ||
059ec3d9 PH |
145 | |
146 | /************************************************* | |
147 | * Initialize and configure resolver * | |
148 | *************************************************/ | |
149 | ||
150 | /* Initialize the resolver and the storage for holding DNS answers if this is | |
151 | the first time we have been here, and set the resolver options. | |
152 | ||
153 | Arguments: | |
154 | qualify_single TRUE to set the RES_DEFNAMES option | |
155 | search_parents TRUE to set the RES_DNSRCH option | |
8c51eead | 156 | use_dnssec TRUE to set the RES_USE_DNSSEC option |
059ec3d9 PH |
157 | |
158 | Returns: nothing | |
159 | */ | |
160 | ||
161 | void | |
8c51eead | 162 | dns_init(BOOL qualify_single, BOOL search_parents, BOOL use_dnssec) |
059ec3d9 | 163 | { |
5bfb4cdf PP |
164 | res_state resp = os_get_dns_resolver_res(); |
165 | ||
166 | if ((resp->options & RES_INIT) == 0) | |
059ec3d9 | 167 | { |
5bfb4cdf PP |
168 | DEBUG(D_resolver) resp->options |= RES_DEBUG; /* For Cygwin */ |
169 | os_put_dns_resolver_res(resp); | |
059ec3d9 | 170 | res_init(); |
5bfb4cdf PP |
171 | DEBUG(D_resolver) resp->options |= RES_DEBUG; |
172 | os_put_dns_resolver_res(resp); | |
059ec3d9 PH |
173 | } |
174 | ||
5bfb4cdf PP |
175 | resp->options &= ~(RES_DNSRCH | RES_DEFNAMES); |
176 | resp->options |= (qualify_single? RES_DEFNAMES : 0) | | |
059ec3d9 | 177 | (search_parents? RES_DNSRCH : 0); |
5bfb4cdf PP |
178 | if (dns_retrans > 0) resp->retrans = dns_retrans; |
179 | if (dns_retry > 0) resp->retry = dns_retry; | |
e97d1f08 PP |
180 | |
181 | #ifdef RES_USE_EDNS0 | |
182 | if (dns_use_edns0 >= 0) | |
183 | { | |
184 | if (dns_use_edns0) | |
5bfb4cdf | 185 | resp->options |= RES_USE_EDNS0; |
e97d1f08 | 186 | else |
5bfb4cdf | 187 | resp->options &= ~RES_USE_EDNS0; |
e97d1f08 PP |
188 | DEBUG(D_resolver) |
189 | debug_printf("Coerced resolver EDNS0 support %s.\n", | |
190 | dns_use_edns0 ? "on" : "off"); | |
191 | } | |
192 | #else | |
193 | if (dns_use_edns0 >= 0) | |
194 | DEBUG(D_resolver) | |
195 | debug_printf("Unable to %sset EDNS0 without resolver support.\n", | |
196 | dns_use_edns0 ? "" : "un"); | |
197 | #endif | |
5bfb4cdf | 198 | |
1f4a55da PP |
199 | #ifndef DISABLE_DNSSEC |
200 | # ifdef RES_USE_DNSSEC | |
201 | # ifndef RES_USE_EDNS0 | |
202 | # error Have RES_USE_DNSSEC but not RES_USE_EDNS0? Something hinky ... | |
203 | # endif | |
8c51eead JH |
204 | if (use_dnssec) |
205 | resp->options |= RES_USE_DNSSEC; | |
0fbd9bff | 206 | if (dns_dnssec_ok >= 0) |
1f4a55da | 207 | { |
0fbd9bff | 208 | if (dns_use_edns0 == 0 && dns_dnssec_ok != 0) |
1f4a55da PP |
209 | { |
210 | DEBUG(D_resolver) | |
0fbd9bff | 211 | debug_printf("CONFLICT: dns_use_edns0 forced false, dns_dnssec_ok forced true, ignoring latter!\n"); |
1f4a55da PP |
212 | } |
213 | else | |
214 | { | |
0fbd9bff | 215 | if (dns_dnssec_ok) |
1f4a55da PP |
216 | resp->options |= RES_USE_DNSSEC; |
217 | else | |
218 | resp->options &= ~RES_USE_DNSSEC; | |
219 | DEBUG(D_resolver) debug_printf("Coerced resolver DNSSEC support %s.\n", | |
0fbd9bff | 220 | dns_dnssec_ok ? "on" : "off"); |
1f4a55da PP |
221 | } |
222 | } | |
223 | # else | |
0fbd9bff | 224 | if (dns_dnssec_ok >= 0) |
1f4a55da PP |
225 | DEBUG(D_resolver) |
226 | debug_printf("Unable to %sset DNSSEC without resolver support.\n", | |
0fbd9bff | 227 | dns_dnssec_ok ? "" : "un"); |
8c51eead JH |
228 | if (use_dnssec) |
229 | DEBUG(D_resolver) | |
93d4b03a | 230 | debug_printf("Unable to set DNSSEC without resolver support.\n"); |
1f4a55da PP |
231 | # endif |
232 | #endif /* DISABLE_DNSSEC */ | |
233 | ||
5bfb4cdf | 234 | os_put_dns_resolver_res(resp); |
059ec3d9 PH |
235 | } |
236 | ||
237 | ||
238 | ||
239 | /************************************************* | |
240 | * Build key name for PTR records * | |
241 | *************************************************/ | |
242 | ||
243 | /* This function inverts an IP address and adds the relevant domain, to produce | |
244 | a name that can be used to look up PTR records. | |
245 | ||
246 | Arguments: | |
247 | string the IP address as a string | |
248 | buffer a suitable buffer, long enough to hold the result | |
249 | ||
250 | Returns: nothing | |
251 | */ | |
252 | ||
253 | void | |
55414b25 | 254 | dns_build_reverse(const uschar *string, uschar *buffer) |
059ec3d9 | 255 | { |
55414b25 | 256 | const uschar *p = string + Ustrlen(string); |
059ec3d9 PH |
257 | uschar *pp = buffer; |
258 | ||
259 | /* Handle IPv4 address */ | |
260 | ||
261 | #if HAVE_IPV6 | |
262 | if (Ustrchr(string, ':') == NULL) | |
263 | #endif | |
264 | { | |
265 | int i; | |
266 | for (i = 0; i < 4; i++) | |
267 | { | |
55414b25 | 268 | const uschar *ppp = p; |
059ec3d9 PH |
269 | while (ppp > string && ppp[-1] != '.') ppp--; |
270 | Ustrncpy(pp, ppp, p - ppp); | |
271 | pp += p - ppp; | |
272 | *pp++ = '.'; | |
273 | p = ppp - 1; | |
274 | } | |
275 | Ustrcpy(pp, "in-addr.arpa"); | |
276 | } | |
277 | ||
278 | /* Handle IPv6 address; convert to binary so as to fill out any | |
279 | abbreviation in the textual form. */ | |
280 | ||
281 | #if HAVE_IPV6 | |
282 | else | |
283 | { | |
284 | int i; | |
285 | int v6[4]; | |
286 | (void)host_aton(string, v6); | |
287 | ||
288 | /* The original specification for IPv6 reverse lookup was to invert each | |
289 | nibble, and look in the ip6.int domain. The domain was subsequently | |
290 | changed to ip6.arpa. */ | |
291 | ||
292 | for (i = 3; i >= 0; i--) | |
293 | { | |
294 | int j; | |
295 | for (j = 0; j < 32; j += 4) | |
296 | { | |
297 | sprintf(CS pp, "%x.", (v6[i] >> j) & 15); | |
298 | pp += 2; | |
299 | } | |
300 | } | |
301 | Ustrcpy(pp, "ip6.arpa."); | |
302 | ||
303 | /* Another way of doing IPv6 reverse lookups was proposed in conjunction | |
304 | with A6 records. However, it fell out of favour when they did. The | |
305 | alternative was to construct a binary key, and look in ip6.arpa. I tried | |
306 | to make this code do that, but I could not make it work on Solaris 8. The | |
307 | resolver seems to lose the initial backslash somehow. However, now that | |
308 | this style of reverse lookup has been dropped, it doesn't matter. These | |
309 | lines are left here purely for historical interest. */ | |
310 | ||
311 | /************************************************** | |
312 | Ustrcpy(pp, "\\[x"); | |
313 | pp += 3; | |
314 | ||
315 | for (i = 0; i < 4; i++) | |
316 | { | |
317 | sprintf(pp, "%08X", v6[i]); | |
318 | pp += 8; | |
319 | } | |
320 | Ustrcpy(pp, "].ip6.arpa."); | |
321 | **************************************************/ | |
322 | ||
323 | } | |
324 | #endif | |
325 | } | |
326 | ||
327 | ||
328 | ||
329 | ||
330 | /************************************************* | |
331 | * Get next DNS record from answer block * | |
332 | *************************************************/ | |
333 | ||
334 | /* Call this with reset == RESET_ANSWERS to scan the answer block, reset == | |
e5a9dba6 PH |
335 | RESET_AUTHORITY to scan the authority records, reset == RESET_ADDITIONAL to |
336 | scan the additional records, and reset == RESET_NEXT to get the next record. | |
337 | The result is in static storage which must be copied if it is to be preserved. | |
059ec3d9 PH |
338 | |
339 | Arguments: | |
340 | dnsa pointer to dns answer block | |
341 | dnss pointer to dns scan block | |
342 | reset option specifing what portion to scan, as described above | |
343 | ||
344 | Returns: next dns record, or NULL when no more | |
345 | */ | |
346 | ||
347 | dns_record * | |
348 | dns_next_rr(dns_answer *dnsa, dns_scan *dnss, int reset) | |
349 | { | |
350 | HEADER *h = (HEADER *)dnsa->answer; | |
351 | int namelen; | |
352 | ||
353 | /* Reset the saved data when requested to, and skip to the first required RR */ | |
354 | ||
355 | if (reset != RESET_NEXT) | |
356 | { | |
357 | dnss->rrcount = ntohs(h->qdcount); | |
358 | dnss->aptr = dnsa->answer + sizeof(HEADER); | |
359 | ||
360 | /* Skip over questions; failure to expand the name just gives up */ | |
361 | ||
362 | while (dnss->rrcount-- > 0) | |
363 | { | |
364 | namelen = dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen, | |
365 | dnss->aptr, (DN_EXPAND_ARG4_TYPE) &(dnss->srr.name), DNS_MAXNAME); | |
366 | if (namelen < 0) { dnss->rrcount = 0; return NULL; } | |
367 | dnss->aptr += namelen + 4; /* skip name & type & class */ | |
368 | } | |
369 | ||
370 | /* Get the number of answer records. */ | |
371 | ||
372 | dnss->rrcount = ntohs(h->ancount); | |
373 | ||
e5a9dba6 PH |
374 | /* Skip over answers if we want to look at the authority section. Also skip |
375 | the NS records (i.e. authority section) if wanting to look at the additional | |
059ec3d9 PH |
376 | records. */ |
377 | ||
e5a9dba6 PH |
378 | if (reset == RESET_ADDITIONAL) dnss->rrcount += ntohs(h->nscount); |
379 | ||
380 | if (reset == RESET_AUTHORITY || reset == RESET_ADDITIONAL) | |
059ec3d9 | 381 | { |
059ec3d9 PH |
382 | while (dnss->rrcount-- > 0) |
383 | { | |
384 | namelen = dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen, | |
385 | dnss->aptr, (DN_EXPAND_ARG4_TYPE) &(dnss->srr.name), DNS_MAXNAME); | |
386 | if (namelen < 0) { dnss->rrcount = 0; return NULL; } | |
387 | dnss->aptr += namelen + 8; /* skip name, type, class & TTL */ | |
388 | GETSHORT(dnss->srr.size, dnss->aptr); /* size of data portion */ | |
389 | dnss->aptr += dnss->srr.size; /* skip over it */ | |
390 | } | |
e5a9dba6 PH |
391 | dnss->rrcount = (reset == RESET_AUTHORITY) |
392 | ? ntohs(h->nscount) : ntohs(h->arcount); | |
059ec3d9 PH |
393 | } |
394 | } | |
395 | ||
059ec3d9 PH |
396 | /* The variable dnss->aptr is now pointing at the next RR, and dnss->rrcount |
397 | contains the number of RR records left. */ | |
398 | ||
399 | if (dnss->rrcount-- <= 0) return NULL; | |
400 | ||
401 | /* If expanding the RR domain name fails, behave as if no more records | |
402 | (something safe). */ | |
403 | ||
404 | namelen = dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen, dnss->aptr, | |
405 | (DN_EXPAND_ARG4_TYPE) &(dnss->srr.name), DNS_MAXNAME); | |
406 | if (namelen < 0) { dnss->rrcount = 0; return NULL; } | |
407 | ||
408 | /* Move the pointer past the name and fill in the rest of the data structure | |
409 | from the following bytes. */ | |
410 | ||
411 | dnss->aptr += namelen; | |
412 | GETSHORT(dnss->srr.type, dnss->aptr); /* Record type */ | |
413 | dnss->aptr += 6; /* Don't want class or TTL */ | |
414 | GETSHORT(dnss->srr.size, dnss->aptr); /* Size of data portion */ | |
415 | dnss->srr.data = dnss->aptr; /* The record's data follows */ | |
416 | dnss->aptr += dnss->srr.size; /* Advance to next RR */ | |
417 | ||
418 | /* Return a pointer to the dns_record structure within the dns_answer. This is | |
419 | for convenience so that the scans can use nice-looking for loops. */ | |
420 | ||
421 | return &(dnss->srr); | |
422 | } | |
423 | ||
424 | ||
425 | ||
426 | ||
1f4a55da PP |
427 | /************************************************* |
428 | * Return whether AD bit set in DNS result * | |
429 | *************************************************/ | |
430 | ||
431 | /* We do not perform DNSSEC work ourselves; if the administrator has installed | |
432 | a verifying resolver which sets AD as appropriate, though, we'll use that. | |
433 | (AD = Authentic Data) | |
434 | ||
435 | Argument: pointer to dns answer block | |
436 | Returns: bool indicating presence of AD bit | |
437 | */ | |
438 | ||
439 | BOOL | |
4a142059 | 440 | dns_is_secure(const dns_answer * dnsa) |
1f4a55da PP |
441 | { |
442 | #ifdef DISABLE_DNSSEC | |
443 | DEBUG(D_dns) | |
444 | debug_printf("DNSSEC support disabled at build-time; dns_is_secure() false\n"); | |
445 | return FALSE; | |
446 | #else | |
447 | HEADER *h = (HEADER *)dnsa->answer; | |
448 | return h->ad ? TRUE : FALSE; | |
449 | #endif | |
450 | } | |
451 | ||
4a142059 JH |
452 | static void |
453 | dns_set_insecure(dns_answer * dnsa) | |
454 | { | |
455 | HEADER * h = (HEADER *)dnsa->answer; | |
456 | h->ad = 0; | |
457 | } | |
458 | ||
1f4a55da PP |
459 | |
460 | ||
461 | ||
059ec3d9 PH |
462 | /************************************************* |
463 | * Turn DNS type into text * | |
464 | *************************************************/ | |
465 | ||
885ccd3e PH |
466 | /* Turn the coded record type into a string for printing. All those that Exim |
467 | uses should be included here. | |
059ec3d9 PH |
468 | |
469 | Argument: record type | |
470 | Returns: pointer to string | |
471 | */ | |
472 | ||
473 | uschar * | |
474 | dns_text_type(int t) | |
475 | { | |
476 | switch(t) | |
477 | { | |
33397d19 PH |
478 | case T_A: return US"A"; |
479 | case T_MX: return US"MX"; | |
480 | case T_AAAA: return US"AAAA"; | |
481 | case T_A6: return US"A6"; | |
482 | case T_TXT: return US"TXT"; | |
eae0036b | 483 | case T_SPF: return US"SPF"; |
33397d19 | 484 | case T_PTR: return US"PTR"; |
885ccd3e | 485 | case T_SOA: return US"SOA"; |
33397d19 PH |
486 | case T_SRV: return US"SRV"; |
487 | case T_NS: return US"NS"; | |
8e669ac1 | 488 | case T_CNAME: return US"CNAME"; |
1e06383a | 489 | case T_TLSA: return US"TLSA"; |
33397d19 | 490 | default: return US"?"; |
059ec3d9 PH |
491 | } |
492 | } | |
493 | ||
494 | ||
495 | ||
496 | /************************************************* | |
497 | * Cache a failed DNS lookup result * | |
498 | *************************************************/ | |
499 | ||
500 | /* We cache failed lookup results so as not to experience timeouts many | |
501 | times for the same domain. We need to retain the resolver options because they | |
502 | may change. For successful lookups, we rely on resolver and/or name server | |
503 | caching. | |
504 | ||
505 | Arguments: | |
506 | name the domain name | |
507 | type the lookup type | |
508 | rc the return code | |
509 | ||
510 | Returns: the return code | |
511 | */ | |
512 | ||
513 | static int | |
1dc92d5a | 514 | dns_return(const uschar * name, int type, int rc) |
059ec3d9 | 515 | { |
5bfb4cdf | 516 | res_state resp = os_get_dns_resolver_res(); |
059ec3d9 PH |
517 | tree_node *node = store_get_perm(sizeof(tree_node) + 290); |
518 | sprintf(CS node->name, "%.255s-%s-%lx", name, dns_text_type(type), | |
5bfb4cdf | 519 | resp->options); |
059ec3d9 PH |
520 | node->data.val = rc; |
521 | (void)tree_insertnode(&tree_dns_fails, node); | |
522 | return rc; | |
523 | } | |
524 | ||
525 | ||
526 | ||
527 | /************************************************* | |
528 | * Do basic DNS lookup * | |
529 | *************************************************/ | |
530 | ||
531 | /* Call the resolver to look up the given domain name, using the given type, | |
532 | and check the result. The error code TRY_AGAIN is documented as meaning "non- | |
533 | Authoritive Host not found, or SERVERFAIL". Sometimes there are badly set | |
534 | up nameservers that produce this error continually, so there is the option of | |
535 | providing a list of domains for which this is treated as a non-existent | |
536 | host. | |
537 | ||
538 | Arguments: | |
539 | dnsa pointer to dns_answer structure | |
540 | name name to look up | |
541 | type type of DNS record required (T_A, T_MX, etc) | |
542 | ||
543 | Returns: DNS_SUCCEED successful lookup | |
544 | DNS_NOMATCH name not found (NXDOMAIN) | |
545 | or name contains illegal characters (if checking) | |
30e18802 | 546 | or name is an IP address (for IP address lookup) |
059ec3d9 PH |
547 | DNS_NODATA domain exists, but no data for this type (NODATA) |
548 | DNS_AGAIN soft failure, try again later | |
549 | DNS_FAIL DNS failure | |
550 | */ | |
551 | ||
552 | int | |
1dc92d5a | 553 | dns_basic_lookup(dns_answer *dnsa, const uschar *name, int type) |
059ec3d9 PH |
554 | { |
555 | #ifndef STAND_ALONE | |
7156b1ef | 556 | int rc = -1; |
55414b25 | 557 | const uschar *save_domain; |
059ec3d9 | 558 | #endif |
5bfb4cdf | 559 | res_state resp = os_get_dns_resolver_res(); |
059ec3d9 PH |
560 | |
561 | tree_node *previous; | |
562 | uschar node_name[290]; | |
563 | ||
564 | /* DNS lookup failures of any kind are cached in a tree. This is mainly so that | |
565 | a timeout on one domain doesn't happen time and time again for messages that | |
566 | have many addresses in the same domain. We rely on the resolver and name server | |
567 | caching for successful lookups. */ | |
568 | ||
569 | sprintf(CS node_name, "%.255s-%s-%lx", name, dns_text_type(type), | |
5bfb4cdf | 570 | resp->options); |
059ec3d9 PH |
571 | previous = tree_search(tree_dns_fails, node_name); |
572 | if (previous != NULL) | |
573 | { | |
574 | DEBUG(D_dns) debug_printf("DNS lookup of %.255s-%s: using cached value %s\n", | |
575 | name, dns_text_type(type), | |
576 | (previous->data.val == DNS_NOMATCH)? "DNS_NOMATCH" : | |
577 | (previous->data.val == DNS_NODATA)? "DNS_NODATA" : | |
578 | (previous->data.val == DNS_AGAIN)? "DNS_AGAIN" : | |
579 | (previous->data.val == DNS_FAIL)? "DNS_FAIL" : "??"); | |
580 | return previous->data.val; | |
581 | } | |
582 | ||
9d4319df JH |
583 | #ifdef EXPERIMENTAL_INTERNATIONAL |
584 | /* Convert all names to a-label form before doing lookup */ | |
585 | { | |
586 | uschar * alabel; | |
587 | uschar * errstr = NULL; | |
766e7a65 JH |
588 | DEBUG(D_dns) if (string_is_utf8(name)) |
589 | debug_printf("convert utf8 '%s' to alabel for for lookup\n", name); | |
9d4319df JH |
590 | if ((alabel = string_domain_utf8_to_alabel(name, &errstr)), errstr) |
591 | { | |
592 | DEBUG(D_dns) | |
37bf366e | 593 | debug_printf("DNS name '%s' utf8 conversion to alabel failed: %s\n", name, |
9d4319df JH |
594 | errstr); |
595 | host_find_failed_syntax = TRUE; | |
596 | return DNS_NOMATCH; | |
597 | } | |
598 | name = alabel; | |
599 | } | |
600 | #endif | |
601 | ||
059ec3d9 PH |
602 | /* If configured, check the hygene of the name passed to lookup. Otherwise, |
603 | although DNS lookups may give REFUSED at the lower level, some resolvers | |
604 | turn this into TRY_AGAIN, which is silly. Give a NOMATCH return, since such | |
605 | domains cannot be in the DNS. The check is now done by a regular expression; | |
606 | give it space for substring storage to save it having to get its own if the | |
607 | regex has substrings that are used - the default uses a conditional. | |
608 | ||
609 | This test is omitted for PTR records. These occur only in calls from the dnsdb | |
610 | lookup, which constructs the names itself, so they should be OK. Besides, | |
611 | bitstring labels don't conform to normal name syntax. (But the aren't used any | |
612 | more.) | |
613 | ||
614 | For SRV records, we omit the initial _smtp._tcp. components at the start. */ | |
615 | ||
616 | #ifndef STAND_ALONE /* Omit this for stand-alone tests */ | |
617 | ||
482d1455 | 618 | if (check_dns_names_pattern[0] != 0 && type != T_PTR && type != T_TXT) |
059ec3d9 | 619 | { |
1dc92d5a | 620 | const uschar *checkname = name; |
059ec3d9 PH |
621 | int ovector[3*(EXPAND_MAXN+1)]; |
622 | ||
476be7e2 | 623 | dns_pattern_init(); |
059ec3d9 PH |
624 | |
625 | /* For an SRV lookup, skip over the first two components (the service and | |
626 | protocol names, which both start with an underscore). */ | |
627 | ||
b4161d10 | 628 | if (type == T_SRV || type == T_TLSA) |
059ec3d9 PH |
629 | { |
630 | while (*checkname++ != '.'); | |
631 | while (*checkname++ != '.'); | |
632 | } | |
633 | ||
1dc92d5a | 634 | if (pcre_exec(regex_check_dns_names, NULL, CCS checkname, Ustrlen(checkname), |
059ec3d9 PH |
635 | 0, PCRE_EOPT, ovector, sizeof(ovector)/sizeof(int)) < 0) |
636 | { | |
637 | DEBUG(D_dns) | |
638 | debug_printf("DNS name syntax check failed: %s (%s)\n", name, | |
639 | dns_text_type(type)); | |
640 | host_find_failed_syntax = TRUE; | |
641 | return DNS_NOMATCH; | |
642 | } | |
643 | } | |
644 | ||
645 | #endif /* STAND_ALONE */ | |
646 | ||
647 | /* Call the resolver; for an overlong response, res_search() will return the | |
bef5a11f PH |
648 | number of bytes the message would need, so we need to check for this case. The |
649 | effect is to truncate overlong data. | |
650 | ||
30e18802 PH |
651 | On some systems, res_search() will recognize "A-for-A" queries and return |
652 | the IP address instead of returning -1 with h_error=HOST_NOT_FOUND. Some | |
653 | nameservers are also believed to do this. It is, of course, contrary to the | |
654 | specification of the DNS, so we lock it out. */ | |
655 | ||
cc00f4af | 656 | if ((type == T_A || type == T_AAAA) && string_is_ip_address(name, NULL) != 0) |
30e18802 PH |
657 | return DNS_NOMATCH; |
658 | ||
659 | /* If we are running in the test harness, instead of calling the normal resolver | |
bef5a11f PH |
660 | (res_search), we call fakens_search(), which recognizes certain special |
661 | domains, and interfaces to a fake nameserver for certain special zones. */ | |
662 | ||
cc00f4af JH |
663 | dnsa->answerlen = running_in_test_harness |
664 | ? fakens_search(name, type, dnsa->answer, MAXPACKET) | |
665 | : res_search(CCS name, C_IN, type, dnsa->answer, MAXPACKET); | |
059ec3d9 | 666 | |
80a47a2c TK |
667 | if (dnsa->answerlen > MAXPACKET) |
668 | { | |
669 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) resulted in overlong packet (size %d), truncating to %d.\n", | |
670 | name, dns_text_type(type), dnsa->answerlen, MAXPACKET); | |
671 | dnsa->answerlen = MAXPACKET; | |
672 | } | |
059ec3d9 PH |
673 | |
674 | if (dnsa->answerlen < 0) switch (h_errno) | |
675 | { | |
676 | case HOST_NOT_FOUND: | |
677 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave HOST_NOT_FOUND\n" | |
678 | "returning DNS_NOMATCH\n", name, dns_text_type(type)); | |
679 | return dns_return(name, type, DNS_NOMATCH); | |
680 | ||
681 | case TRY_AGAIN: | |
682 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave TRY_AGAIN\n", | |
683 | name, dns_text_type(type)); | |
684 | ||
685 | /* Cut this out for various test programs */ | |
1dc92d5a | 686 | #ifndef STAND_ALONE |
55414b25 | 687 | save_domain = deliver_domain; |
1dc92d5a | 688 | deliver_domain = string_copy(name); /* set $domain */ |
55414b25 | 689 | rc = match_isinlist(name, (const uschar **)&dns_again_means_nonexist, 0, NULL, NULL, |
059ec3d9 | 690 | MCL_DOMAIN, TRUE, NULL); |
55414b25 | 691 | deliver_domain = save_domain; |
059ec3d9 PH |
692 | if (rc != OK) |
693 | { | |
694 | DEBUG(D_dns) debug_printf("returning DNS_AGAIN\n"); | |
695 | return dns_return(name, type, DNS_AGAIN); | |
696 | } | |
697 | DEBUG(D_dns) debug_printf("%s is in dns_again_means_nonexist: returning " | |
698 | "DNS_NOMATCH\n", name); | |
699 | return dns_return(name, type, DNS_NOMATCH); | |
700 | ||
1dc92d5a | 701 | #else /* For stand-alone tests */ |
059ec3d9 | 702 | return dns_return(name, type, DNS_AGAIN); |
1dc92d5a | 703 | #endif |
059ec3d9 PH |
704 | |
705 | case NO_RECOVERY: | |
706 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave NO_RECOVERY\n" | |
707 | "returning DNS_FAIL\n", name, dns_text_type(type)); | |
708 | return dns_return(name, type, DNS_FAIL); | |
709 | ||
710 | case NO_DATA: | |
711 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave NO_DATA\n" | |
712 | "returning DNS_NODATA\n", name, dns_text_type(type)); | |
713 | return dns_return(name, type, DNS_NODATA); | |
714 | ||
715 | default: | |
716 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave unknown DNS error %d\n" | |
717 | "returning DNS_FAIL\n", name, dns_text_type(type), h_errno); | |
718 | return dns_return(name, type, DNS_FAIL); | |
719 | } | |
720 | ||
721 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) succeeded\n", | |
722 | name, dns_text_type(type)); | |
723 | ||
724 | return DNS_SUCCEED; | |
725 | } | |
726 | ||
727 | ||
728 | ||
729 | ||
730 | /************************************************ | |
731 | * Do a DNS lookup and handle CNAMES * | |
732 | ************************************************/ | |
733 | ||
734 | /* Look up the given domain name, using the given type. Follow CNAMEs if | |
735 | necessary, but only so many times. There aren't supposed to be CNAME chains in | |
736 | the DNS, but you are supposed to cope with them if you find them. | |
737 | ||
738 | The assumption is made that if the resolver gives back records of the | |
739 | requested type *and* a CNAME, we don't need to make another call to look up | |
740 | the CNAME. I can't see how it could return only some of the right records. If | |
741 | it's done a CNAME lookup in the past, it will have all of them; if not, it | |
742 | won't return any. | |
743 | ||
744 | If fully_qualified_name is not NULL, set it to point to the full name | |
745 | returned by the resolver, if this is different to what it is given, unless | |
746 | the returned name starts with "*" as some nameservers seem to be returning | |
766e7a65 JH |
747 | wildcards in this form. In international mode "different" means "alabel |
748 | forms are different". | |
059ec3d9 PH |
749 | |
750 | Arguments: | |
751 | dnsa pointer to dns_answer structure | |
752 | name domain name to look up | |
753 | type DNS record type (T_A, T_MX, etc) | |
754 | fully_qualified_name if not NULL, return the returned name here if its | |
755 | contents are different (i.e. it must be preset) | |
756 | ||
757 | Returns: DNS_SUCCEED successful lookup | |
758 | DNS_NOMATCH name not found | |
759 | DNS_NODATA no data found | |
760 | DNS_AGAIN soft failure, try again later | |
761 | DNS_FAIL DNS failure | |
762 | */ | |
763 | ||
764 | int | |
1dc92d5a | 765 | dns_lookup(dns_answer *dnsa, const uschar *name, int type, |
55414b25 | 766 | const uschar **fully_qualified_name) |
059ec3d9 PH |
767 | { |
768 | int i; | |
1dc92d5a | 769 | const uschar *orig_name = name; |
c85b3043 | 770 | BOOL secure_so_far = TRUE; |
059ec3d9 PH |
771 | |
772 | /* Loop to follow CNAME chains so far, but no further... */ | |
773 | ||
774 | for (i = 0; i < 10; i++) | |
775 | { | |
776 | uschar data[256]; | |
777 | dns_record *rr, cname_rr, type_rr; | |
778 | dns_scan dnss; | |
779 | int datalen, rc; | |
780 | ||
781 | /* DNS lookup failures get passed straight back. */ | |
782 | ||
783 | if ((rc = dns_basic_lookup(dnsa, name, type)) != DNS_SUCCEED) return rc; | |
784 | ||
785 | /* We should have either records of the required type, or a CNAME record, | |
786 | or both. We need to know whether both exist for getting the fully qualified | |
787 | name, but avoid scanning more than necessary. Note that we must copy the | |
788 | contents of any rr blocks returned by dns_next_rr() as they use the same | |
789 | area in the dnsa block. */ | |
790 | ||
791 | cname_rr.data = type_rr.data = NULL; | |
792 | for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); | |
793 | rr != NULL; | |
794 | rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)) | |
795 | { | |
796 | if (rr->type == type) | |
797 | { | |
798 | if (type_rr.data == NULL) type_rr = *rr; | |
799 | if (cname_rr.data != NULL) break; | |
800 | } | |
801 | else if (rr->type == T_CNAME) cname_rr = *rr; | |
802 | } | |
803 | ||
a2042e78 PH |
804 | /* For the first time round this loop, if a CNAME was found, take the fully |
805 | qualified name from it; otherwise from the first data record, if present. */ | |
059ec3d9 | 806 | |
a2042e78 | 807 | if (i == 0 && fully_qualified_name != NULL) |
059ec3d9 | 808 | { |
766e7a65 JH |
809 | uschar * rr_name = cname_rr.data ? cname_rr.name |
810 | : type_rr.data ? type_rr.name : NULL; | |
811 | if ( rr_name | |
812 | && Ustrcmp(rr_name, *fully_qualified_name) != 0 | |
813 | && rr_name[0] != '*' | |
814 | #ifdef EXPERIMENTAL_INTERNATIONAL | |
815 | && ( !string_is_utf8(*fully_qualified_name) | |
816 | || Ustrcmp(rr_name, | |
817 | string_domain_utf8_to_alabel(*fully_qualified_name, NULL)) != 0 | |
818 | ) | |
819 | #endif | |
820 | ) | |
821 | *fully_qualified_name = string_copy_dnsdomain(rr_name); | |
059ec3d9 PH |
822 | } |
823 | ||
824 | /* If any data records of the correct type were found, we are done. */ | |
825 | ||
c85b3043 JH |
826 | if (type_rr.data != NULL) |
827 | { | |
828 | if (!secure_so_far) /* mark insecure if any element of CNAME chain was */ | |
4a142059 | 829 | dns_set_insecure(dnsa); |
c85b3043 JH |
830 | return DNS_SUCCEED; |
831 | } | |
059ec3d9 PH |
832 | |
833 | /* If there are no data records, we need to re-scan the DNS using the | |
834 | domain given in the CNAME record, which should exist (otherwise we should | |
835 | have had a failure from dns_lookup). However code against the possibility of | |
836 | its not existing. */ | |
837 | ||
838 | if (cname_rr.data == NULL) return DNS_FAIL; | |
839 | datalen = dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen, | |
1dc92d5a | 840 | cname_rr.data, (DN_EXPAND_ARG4_TYPE)data, sizeof(data)); |
059ec3d9 PH |
841 | if (datalen < 0) return DNS_FAIL; |
842 | name = data; | |
a2042e78 | 843 | |
c85b3043 JH |
844 | if (!dns_is_secure(dnsa)) |
845 | secure_so_far = FALSE; | |
846 | ||
a2042e78 | 847 | DEBUG(D_dns) debug_printf("CNAME found: change to %s\n", name); |
059ec3d9 PH |
848 | } /* Loop back to do another lookup */ |
849 | ||
850 | /*Control reaches here after 10 times round the CNAME loop. Something isn't | |
851 | right... */ | |
852 | ||
853 | log_write(0, LOG_MAIN, "CNAME loop for %s encountered", orig_name); | |
854 | return DNS_FAIL; | |
855 | } | |
856 | ||
857 | ||
858 | ||
33397d19 PH |
859 | |
860 | ||
861 | ||
862 | /************************************************ | |
863 | * Do a DNS lookup and handle virtual types * | |
864 | ************************************************/ | |
865 | ||
8e669ac1 PH |
866 | /* This function handles some invented "lookup types" that synthesize feature |
867 | not available in the basic types. The special types all have negative values. | |
33397d19 PH |
868 | Positive type values are passed straight on to dns_lookup(). |
869 | ||
870 | Arguments: | |
871 | dnsa pointer to dns_answer structure | |
872 | name domain name to look up | |
873 | type DNS record type (T_A, T_MX, etc or a "special") | |
874 | fully_qualified_name if not NULL, return the returned name here if its | |
875 | contents are different (i.e. it must be preset) | |
876 | ||
877 | Returns: DNS_SUCCEED successful lookup | |
878 | DNS_NOMATCH name not found | |
879 | DNS_NODATA no data found | |
880 | DNS_AGAIN soft failure, try again later | |
881 | DNS_FAIL DNS failure | |
882 | */ | |
883 | ||
884 | int | |
1dc92d5a | 885 | dns_special_lookup(dns_answer *dnsa, const uschar *name, int type, |
55414b25 | 886 | const uschar **fully_qualified_name) |
33397d19 | 887 | { |
d2a2c69b | 888 | switch (type) |
e5a9dba6 | 889 | { |
d2a2c69b JH |
890 | /* The "mx hosts only" type doesn't require any special action here */ |
891 | case T_MXH: | |
892 | return dns_lookup(dnsa, name, T_MX, fully_qualified_name); | |
893 | ||
894 | /* Find nameservers for the domain or the nearest enclosing zone, excluding | |
895 | the root servers. */ | |
896 | case T_ZNS: | |
897 | type = T_NS; | |
898 | /* FALLTHROUGH */ | |
899 | case T_SOA: | |
900 | { | |
901 | const uschar *d = name; | |
902 | while (d != 0) | |
903 | { | |
904 | int rc = dns_lookup(dnsa, d, type, fully_qualified_name); | |
905 | if (rc != DNS_NOMATCH && rc != DNS_NODATA) return rc; | |
906 | while (*d != 0 && *d != '.') d++; | |
907 | if (*d++ == 0) break; | |
908 | } | |
909 | return DNS_NOMATCH; | |
910 | } | |
911 | ||
912 | /* Try to look up the Client SMTP Authorization SRV record for the name. If | |
913 | there isn't one, search from the top downwards for a CSA record in a parent | |
914 | domain, which might be making assertions about subdomains. If we find a record | |
915 | we set fully_qualified_name to whichever lookup succeeded, so that the caller | |
916 | can tell whether to look at the explicit authorization field or the subdomain | |
917 | assertion field. */ | |
918 | case T_CSA: | |
919 | { | |
920 | uschar *srvname, *namesuff, *tld, *p; | |
921 | int priority, weight, port; | |
922 | int limit, rc, i; | |
923 | BOOL ipv6; | |
924 | dns_record *rr; | |
925 | dns_scan dnss; | |
926 | ||
927 | DEBUG(D_dns) debug_printf("CSA lookup of %s\n", name); | |
928 | ||
929 | srvname = string_sprintf("_client._smtp.%s", name); | |
930 | rc = dns_lookup(dnsa, srvname, T_SRV, NULL); | |
931 | if (rc == DNS_SUCCEED || rc == DNS_AGAIN) | |
932 | { | |
933 | if (rc == DNS_SUCCEED) *fully_qualified_name = string_copy(name); | |
934 | return rc; | |
935 | } | |
936 | ||
937 | /* Search for CSA subdomain assertion SRV records from the top downwards, | |
938 | starting with the 2nd level domain. This order maximizes cache-friendliness. | |
939 | We skip the top level domains to avoid loading their nameservers and because | |
940 | we know they'll never have CSA SRV records. */ | |
941 | ||
942 | namesuff = Ustrrchr(name, '.'); | |
943 | if (namesuff == NULL) return DNS_NOMATCH; | |
944 | tld = namesuff + 1; | |
945 | ipv6 = FALSE; | |
946 | limit = dns_csa_search_limit; | |
947 | ||
948 | /* Use more appropriate search parameters if we are in the reverse DNS. */ | |
949 | ||
950 | if (strcmpic(namesuff, US".arpa") == 0) | |
951 | { | |
952 | if (namesuff - 8 > name && strcmpic(namesuff - 8, US".in-addr.arpa") == 0) | |
953 | { | |
954 | namesuff -= 8; | |
955 | tld = namesuff + 1; | |
956 | limit = 3; | |
957 | } | |
958 | else if (namesuff - 4 > name && strcmpic(namesuff - 4, US".ip6.arpa") == 0) | |
959 | { | |
960 | namesuff -= 4; | |
961 | tld = namesuff + 1; | |
962 | ipv6 = TRUE; | |
963 | limit = 3; | |
964 | } | |
965 | } | |
966 | ||
967 | DEBUG(D_dns) debug_printf("CSA TLD %s\n", tld); | |
968 | ||
969 | /* Do not perform the search if the top level or 2nd level domains do not | |
970 | exist. This is quite common, and when it occurs all the search queries would | |
971 | go to the root or TLD name servers, which is not friendly. So we check the | |
972 | AUTHORITY section; if it contains the root's SOA record or the TLD's SOA then | |
973 | the TLD or the 2LD (respectively) doesn't exist and we can skip the search. | |
974 | If the TLD and the 2LD exist but the explicit CSA record lookup failed, then | |
975 | the AUTHORITY SOA will be the 2LD's or a subdomain thereof. */ | |
976 | ||
977 | if (rc == DNS_NOMATCH) | |
978 | { | |
979 | /* This is really gross. The successful return value from res_search() is | |
980 | the packet length, which is stored in dnsa->answerlen. If we get a | |
981 | negative DNS reply then res_search() returns -1, which causes the bounds | |
982 | checks for name decompression to fail when it is treated as a packet | |
983 | length, which in turn causes the authority search to fail. The correct | |
984 | packet length has been lost inside libresolv, so we have to guess a | |
985 | replacement value. (The only way to fix this properly would be to | |
986 | re-implement res_search() and res_query() so that they don't muddle their | |
987 | success and packet length return values.) For added safety we only reset | |
988 | the packet length if the packet header looks plausible. */ | |
989 | ||
990 | HEADER *h = (HEADER *)dnsa->answer; | |
991 | if (h->qr == 1 && h->opcode == QUERY && h->tc == 0 | |
992 | && (h->rcode == NOERROR || h->rcode == NXDOMAIN) | |
993 | && ntohs(h->qdcount) == 1 && ntohs(h->ancount) == 0 | |
994 | && ntohs(h->nscount) >= 1) | |
995 | dnsa->answerlen = MAXPACKET; | |
996 | ||
997 | for (rr = dns_next_rr(dnsa, &dnss, RESET_AUTHORITY); | |
998 | rr != NULL; | |
999 | rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)) | |
1000 | if (rr->type != T_SOA) continue; | |
1001 | else if (strcmpic(rr->name, US"") == 0 || | |
1002 | strcmpic(rr->name, tld) == 0) return DNS_NOMATCH; | |
1003 | else break; | |
1004 | } | |
1005 | ||
1006 | for (i = 0; i < limit; i++) | |
1007 | { | |
1008 | if (ipv6) | |
1009 | { | |
1010 | /* Scan through the IPv6 reverse DNS in chunks of 16 bits worth of IP | |
1011 | address, i.e. 4 hex chars and 4 dots, i.e. 8 chars. */ | |
1012 | namesuff -= 8; | |
1013 | if (namesuff <= name) return DNS_NOMATCH; | |
1014 | } | |
1015 | else | |
1016 | /* Find the start of the preceding domain name label. */ | |
1017 | do | |
1018 | if (--namesuff <= name) return DNS_NOMATCH; | |
1019 | while (*namesuff != '.'); | |
1020 | ||
1021 | DEBUG(D_dns) debug_printf("CSA parent search at %s\n", namesuff + 1); | |
1022 | ||
1023 | srvname = string_sprintf("_client._smtp.%s", namesuff + 1); | |
1024 | rc = dns_lookup(dnsa, srvname, T_SRV, NULL); | |
1025 | if (rc == DNS_AGAIN) return rc; | |
1026 | if (rc != DNS_SUCCEED) continue; | |
1027 | ||
1028 | /* Check that the SRV record we have found is worth returning. We don't | |
1029 | just return the first one we find, because some lower level SRV record | |
1030 | might make stricter assertions than its parent domain. */ | |
1031 | ||
1032 | for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); | |
1033 | rr != NULL; | |
1034 | rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)) | |
1035 | { | |
1036 | if (rr->type != T_SRV) continue; | |
1037 | ||
1038 | /* Extract the numerical SRV fields (p is incremented) */ | |
1039 | p = rr->data; | |
1040 | GETSHORT(priority, p); | |
1041 | GETSHORT(weight, p); weight = weight; /* compiler quietening */ | |
1042 | GETSHORT(port, p); | |
1043 | ||
1044 | /* Check the CSA version number */ | |
1045 | if (priority != 1) continue; | |
1046 | ||
1047 | /* If it's making an interesting assertion, return this response. */ | |
1048 | if (port & 1) | |
1049 | { | |
1050 | *fully_qualified_name = namesuff + 1; | |
1051 | return DNS_SUCCEED; | |
1052 | } | |
1053 | } | |
1054 | } | |
1055 | return DNS_NOMATCH; | |
1056 | } | |
e5a9dba6 | 1057 | |
d2a2c69b JH |
1058 | default: |
1059 | if (type >= 0) | |
1060 | return dns_lookup(dnsa, name, type, fully_qualified_name); | |
e5a9dba6 PH |
1061 | } |
1062 | ||
33397d19 PH |
1063 | /* Control should never reach here */ |
1064 | ||
1065 | return DNS_FAIL; | |
1066 | } | |
1067 | ||
1068 | ||
1069 | ||
059ec3d9 PH |
1070 | |
1071 | ||
1072 | /************************************************* | |
1073 | * Get address(es) from DNS record * | |
1074 | *************************************************/ | |
1075 | ||
1076 | /* The record type is either T_A for an IPv4 address or T_AAAA (or T_A6 when | |
d2a2c69b | 1077 | supported) for an IPv6 address. |
059ec3d9 PH |
1078 | |
1079 | Argument: | |
1080 | dnsa the DNS answer block | |
1081 | rr the RR | |
1082 | ||
d2a2c69b | 1083 | Returns: pointer to a chain of dns_address items |
059ec3d9 PH |
1084 | */ |
1085 | ||
1086 | dns_address * | |
1087 | dns_address_from_rr(dns_answer *dnsa, dns_record *rr) | |
1088 | { | |
1089 | dns_address *yield = NULL; | |
1090 | ||
059ec3d9 | 1091 | dnsa = dnsa; /* Stop picky compilers warning */ |
059ec3d9 PH |
1092 | |
1093 | if (rr->type == T_A) | |
1094 | { | |
d2a2c69b | 1095 | uschar *p = US rr->data; |
059ec3d9 PH |
1096 | yield = store_get(sizeof(dns_address) + 20); |
1097 | (void)sprintf(CS yield->address, "%d.%d.%d.%d", p[0], p[1], p[2], p[3]); | |
1098 | yield->next = NULL; | |
1099 | } | |
1100 | ||
1101 | #if HAVE_IPV6 | |
1102 | ||
059ec3d9 PH |
1103 | else |
1104 | { | |
1105 | yield = store_get(sizeof(dns_address) + 50); | |
d2a2c69b | 1106 | inet_ntop(AF_INET6, US rr->data, CS yield->address, 50); |
059ec3d9 PH |
1107 | yield->next = NULL; |
1108 | } | |
1109 | #endif /* HAVE_IPV6 */ | |
1110 | ||
1111 | return yield; | |
1112 | } | |
1113 | ||
476be7e2 JH |
1114 | |
1115 | ||
1116 | void | |
1117 | dns_pattern_init(void) | |
1118 | { | |
1119 | if (check_dns_names_pattern[0] != 0 && !regex_check_dns_names) | |
1120 | regex_check_dns_names = | |
1121 | regex_must_compile(check_dns_names_pattern, FALSE, TRUE); | |
1122 | } | |
1123 | ||
8c51eead JH |
1124 | /* vi: aw ai sw=2 |
1125 | */ | |
059ec3d9 | 1126 | /* End of dns.c */ |