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 | ||
3735e326 | 93 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) using fakens\n", name, dns_text_type(type)); |
433a2980 PH |
94 | |
95 | argv[0] = utilname; | |
5f3d0983 | 96 | argv[1] = config_main_directory; |
433a2980 PH |
97 | argv[2] = name; |
98 | argv[3] = dns_text_type(type); | |
99 | argv[4] = NULL; | |
100 | ||
101 | pid = child_open(argv, NULL, 0000, &infd, &outfd, FALSE); | |
102 | if (pid < 0) | |
103 | log_write(0, LOG_MAIN|LOG_PANIC_DIE, "failed to run fakens: %s", | |
104 | strerror(errno)); | |
105 | ||
106 | len = 0; | |
107 | rc = -1; | |
108 | while (asize > 0 && (rc = read(outfd, aptr, asize)) > 0) | |
109 | { | |
110 | len += rc; | |
111 | aptr += rc; /* Don't modify the actual arguments, because they */ | |
112 | asize -= rc; /* may need to be passed on to res_search(). */ | |
113 | } | |
bef5a11f | 114 | |
1fb7660f JH |
115 | /* If we ran out of output buffer before exhasting the return, |
116 | carry on reading and counting it. */ | |
117 | ||
118 | if (asize == 0) | |
119 | while ((rc = read(outfd, name, sizeof(name))) > 0) | |
120 | len += rc; | |
121 | ||
433a2980 PH |
122 | if (rc < 0) |
123 | log_write(0, LOG_MAIN|LOG_PANIC_DIE, "read from fakens failed: %s", | |
124 | strerror(errno)); | |
bef5a11f | 125 | |
433a2980 | 126 | switch(child_close(pid, 0)) |
bef5a11f | 127 | { |
433a2980 PH |
128 | case 0: return len; |
129 | case 1: h_errno = HOST_NOT_FOUND; return -1; | |
130 | case 2: h_errno = TRY_AGAIN; return -1; | |
131 | default: | |
132 | case 3: h_errno = NO_RECOVERY; return -1; | |
133 | case 4: h_errno = NO_DATA; return -1; | |
134 | case 5: /* Pass on to res_search() */ | |
135 | DEBUG(D_dns) debug_printf("fakens returned PASS_ON\n"); | |
bef5a11f PH |
136 | } |
137 | } | |
8e013028 HSHR |
138 | else |
139 | { | |
140 | DEBUG(D_dns) debug_printf("fakens (%s) not found\n", utilname); | |
141 | } | |
bef5a11f | 142 | |
433a2980 | 143 | /* fakens utility not found, or it returned "pass on" */ |
bef5a11f | 144 | |
433a2980 | 145 | DEBUG(D_dns) debug_printf("passing %s on to res_search()\n", domain); |
e7726cbf PH |
146 | |
147 | return res_search(CS domain, C_IN, type, answerptr, size); | |
bef5a11f PH |
148 | } |
149 | ||
150 | ||
059ec3d9 PH |
151 | |
152 | /************************************************* | |
153 | * Initialize and configure resolver * | |
154 | *************************************************/ | |
155 | ||
156 | /* Initialize the resolver and the storage for holding DNS answers if this is | |
157 | the first time we have been here, and set the resolver options. | |
158 | ||
159 | Arguments: | |
160 | qualify_single TRUE to set the RES_DEFNAMES option | |
161 | search_parents TRUE to set the RES_DNSRCH option | |
8c51eead | 162 | use_dnssec TRUE to set the RES_USE_DNSSEC option |
059ec3d9 PH |
163 | |
164 | Returns: nothing | |
165 | */ | |
166 | ||
167 | void | |
8c51eead | 168 | dns_init(BOOL qualify_single, BOOL search_parents, BOOL use_dnssec) |
059ec3d9 | 169 | { |
5bfb4cdf PP |
170 | res_state resp = os_get_dns_resolver_res(); |
171 | ||
172 | if ((resp->options & RES_INIT) == 0) | |
059ec3d9 | 173 | { |
5bfb4cdf PP |
174 | DEBUG(D_resolver) resp->options |= RES_DEBUG; /* For Cygwin */ |
175 | os_put_dns_resolver_res(resp); | |
059ec3d9 | 176 | res_init(); |
5bfb4cdf PP |
177 | DEBUG(D_resolver) resp->options |= RES_DEBUG; |
178 | os_put_dns_resolver_res(resp); | |
059ec3d9 PH |
179 | } |
180 | ||
5bfb4cdf PP |
181 | resp->options &= ~(RES_DNSRCH | RES_DEFNAMES); |
182 | resp->options |= (qualify_single? RES_DEFNAMES : 0) | | |
059ec3d9 | 183 | (search_parents? RES_DNSRCH : 0); |
5bfb4cdf PP |
184 | if (dns_retrans > 0) resp->retrans = dns_retrans; |
185 | if (dns_retry > 0) resp->retry = dns_retry; | |
e97d1f08 PP |
186 | |
187 | #ifdef RES_USE_EDNS0 | |
188 | if (dns_use_edns0 >= 0) | |
189 | { | |
190 | if (dns_use_edns0) | |
5bfb4cdf | 191 | resp->options |= RES_USE_EDNS0; |
e97d1f08 | 192 | else |
5bfb4cdf | 193 | resp->options &= ~RES_USE_EDNS0; |
e97d1f08 PP |
194 | DEBUG(D_resolver) |
195 | debug_printf("Coerced resolver EDNS0 support %s.\n", | |
196 | dns_use_edns0 ? "on" : "off"); | |
197 | } | |
198 | #else | |
199 | if (dns_use_edns0 >= 0) | |
200 | DEBUG(D_resolver) | |
201 | debug_printf("Unable to %sset EDNS0 without resolver support.\n", | |
202 | dns_use_edns0 ? "" : "un"); | |
203 | #endif | |
5bfb4cdf | 204 | |
1f4a55da PP |
205 | #ifndef DISABLE_DNSSEC |
206 | # ifdef RES_USE_DNSSEC | |
207 | # ifndef RES_USE_EDNS0 | |
208 | # error Have RES_USE_DNSSEC but not RES_USE_EDNS0? Something hinky ... | |
209 | # endif | |
8c51eead JH |
210 | if (use_dnssec) |
211 | resp->options |= RES_USE_DNSSEC; | |
0fbd9bff | 212 | if (dns_dnssec_ok >= 0) |
1f4a55da | 213 | { |
0fbd9bff | 214 | if (dns_use_edns0 == 0 && dns_dnssec_ok != 0) |
1f4a55da PP |
215 | { |
216 | DEBUG(D_resolver) | |
0fbd9bff | 217 | debug_printf("CONFLICT: dns_use_edns0 forced false, dns_dnssec_ok forced true, ignoring latter!\n"); |
1f4a55da PP |
218 | } |
219 | else | |
220 | { | |
0fbd9bff | 221 | if (dns_dnssec_ok) |
1f4a55da PP |
222 | resp->options |= RES_USE_DNSSEC; |
223 | else | |
224 | resp->options &= ~RES_USE_DNSSEC; | |
225 | DEBUG(D_resolver) debug_printf("Coerced resolver DNSSEC support %s.\n", | |
0fbd9bff | 226 | dns_dnssec_ok ? "on" : "off"); |
1f4a55da PP |
227 | } |
228 | } | |
229 | # else | |
0fbd9bff | 230 | if (dns_dnssec_ok >= 0) |
1f4a55da PP |
231 | DEBUG(D_resolver) |
232 | debug_printf("Unable to %sset DNSSEC without resolver support.\n", | |
0fbd9bff | 233 | dns_dnssec_ok ? "" : "un"); |
8c51eead JH |
234 | if (use_dnssec) |
235 | DEBUG(D_resolver) | |
93d4b03a | 236 | debug_printf("Unable to set DNSSEC without resolver support.\n"); |
1f4a55da PP |
237 | # endif |
238 | #endif /* DISABLE_DNSSEC */ | |
239 | ||
5bfb4cdf | 240 | os_put_dns_resolver_res(resp); |
059ec3d9 PH |
241 | } |
242 | ||
243 | ||
244 | ||
245 | /************************************************* | |
246 | * Build key name for PTR records * | |
247 | *************************************************/ | |
248 | ||
249 | /* This function inverts an IP address and adds the relevant domain, to produce | |
250 | a name that can be used to look up PTR records. | |
251 | ||
252 | Arguments: | |
253 | string the IP address as a string | |
254 | buffer a suitable buffer, long enough to hold the result | |
255 | ||
256 | Returns: nothing | |
257 | */ | |
258 | ||
259 | void | |
55414b25 | 260 | dns_build_reverse(const uschar *string, uschar *buffer) |
059ec3d9 | 261 | { |
55414b25 | 262 | const uschar *p = string + Ustrlen(string); |
059ec3d9 PH |
263 | uschar *pp = buffer; |
264 | ||
265 | /* Handle IPv4 address */ | |
266 | ||
267 | #if HAVE_IPV6 | |
268 | if (Ustrchr(string, ':') == NULL) | |
269 | #endif | |
270 | { | |
271 | int i; | |
272 | for (i = 0; i < 4; i++) | |
273 | { | |
55414b25 | 274 | const uschar *ppp = p; |
059ec3d9 PH |
275 | while (ppp > string && ppp[-1] != '.') ppp--; |
276 | Ustrncpy(pp, ppp, p - ppp); | |
277 | pp += p - ppp; | |
278 | *pp++ = '.'; | |
279 | p = ppp - 1; | |
280 | } | |
281 | Ustrcpy(pp, "in-addr.arpa"); | |
282 | } | |
283 | ||
284 | /* Handle IPv6 address; convert to binary so as to fill out any | |
285 | abbreviation in the textual form. */ | |
286 | ||
287 | #if HAVE_IPV6 | |
288 | else | |
289 | { | |
290 | int i; | |
291 | int v6[4]; | |
292 | (void)host_aton(string, v6); | |
293 | ||
294 | /* The original specification for IPv6 reverse lookup was to invert each | |
295 | nibble, and look in the ip6.int domain. The domain was subsequently | |
296 | changed to ip6.arpa. */ | |
297 | ||
298 | for (i = 3; i >= 0; i--) | |
299 | { | |
300 | int j; | |
301 | for (j = 0; j < 32; j += 4) | |
302 | { | |
303 | sprintf(CS pp, "%x.", (v6[i] >> j) & 15); | |
304 | pp += 2; | |
305 | } | |
306 | } | |
307 | Ustrcpy(pp, "ip6.arpa."); | |
308 | ||
309 | /* Another way of doing IPv6 reverse lookups was proposed in conjunction | |
310 | with A6 records. However, it fell out of favour when they did. The | |
311 | alternative was to construct a binary key, and look in ip6.arpa. I tried | |
312 | to make this code do that, but I could not make it work on Solaris 8. The | |
313 | resolver seems to lose the initial backslash somehow. However, now that | |
314 | this style of reverse lookup has been dropped, it doesn't matter. These | |
315 | lines are left here purely for historical interest. */ | |
316 | ||
317 | /************************************************** | |
318 | Ustrcpy(pp, "\\[x"); | |
319 | pp += 3; | |
320 | ||
321 | for (i = 0; i < 4; i++) | |
322 | { | |
323 | sprintf(pp, "%08X", v6[i]); | |
324 | pp += 8; | |
325 | } | |
326 | Ustrcpy(pp, "].ip6.arpa."); | |
327 | **************************************************/ | |
328 | ||
329 | } | |
330 | #endif | |
331 | } | |
332 | ||
333 | ||
334 | ||
335 | ||
336 | /************************************************* | |
337 | * Get next DNS record from answer block * | |
338 | *************************************************/ | |
339 | ||
340 | /* Call this with reset == RESET_ANSWERS to scan the answer block, reset == | |
e5a9dba6 PH |
341 | RESET_AUTHORITY to scan the authority records, reset == RESET_ADDITIONAL to |
342 | scan the additional records, and reset == RESET_NEXT to get the next record. | |
343 | The result is in static storage which must be copied if it is to be preserved. | |
059ec3d9 PH |
344 | |
345 | Arguments: | |
346 | dnsa pointer to dns answer block | |
347 | dnss pointer to dns scan block | |
348 | reset option specifing what portion to scan, as described above | |
349 | ||
350 | Returns: next dns record, or NULL when no more | |
351 | */ | |
352 | ||
353 | dns_record * | |
354 | dns_next_rr(dns_answer *dnsa, dns_scan *dnss, int reset) | |
355 | { | |
356 | HEADER *h = (HEADER *)dnsa->answer; | |
357 | int namelen; | |
358 | ||
359 | /* Reset the saved data when requested to, and skip to the first required RR */ | |
360 | ||
361 | if (reset != RESET_NEXT) | |
362 | { | |
363 | dnss->rrcount = ntohs(h->qdcount); | |
364 | dnss->aptr = dnsa->answer + sizeof(HEADER); | |
365 | ||
366 | /* Skip over questions; failure to expand the name just gives up */ | |
367 | ||
368 | while (dnss->rrcount-- > 0) | |
369 | { | |
370 | namelen = dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen, | |
371 | dnss->aptr, (DN_EXPAND_ARG4_TYPE) &(dnss->srr.name), DNS_MAXNAME); | |
372 | if (namelen < 0) { dnss->rrcount = 0; return NULL; } | |
373 | dnss->aptr += namelen + 4; /* skip name & type & class */ | |
374 | } | |
375 | ||
376 | /* Get the number of answer records. */ | |
377 | ||
378 | dnss->rrcount = ntohs(h->ancount); | |
379 | ||
e5a9dba6 PH |
380 | /* Skip over answers if we want to look at the authority section. Also skip |
381 | the NS records (i.e. authority section) if wanting to look at the additional | |
059ec3d9 PH |
382 | records. */ |
383 | ||
e5a9dba6 PH |
384 | if (reset == RESET_ADDITIONAL) dnss->rrcount += ntohs(h->nscount); |
385 | ||
386 | if (reset == RESET_AUTHORITY || reset == RESET_ADDITIONAL) | |
059ec3d9 | 387 | { |
059ec3d9 PH |
388 | while (dnss->rrcount-- > 0) |
389 | { | |
390 | namelen = dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen, | |
391 | dnss->aptr, (DN_EXPAND_ARG4_TYPE) &(dnss->srr.name), DNS_MAXNAME); | |
392 | if (namelen < 0) { dnss->rrcount = 0; return NULL; } | |
393 | dnss->aptr += namelen + 8; /* skip name, type, class & TTL */ | |
394 | GETSHORT(dnss->srr.size, dnss->aptr); /* size of data portion */ | |
395 | dnss->aptr += dnss->srr.size; /* skip over it */ | |
396 | } | |
e5a9dba6 PH |
397 | dnss->rrcount = (reset == RESET_AUTHORITY) |
398 | ? ntohs(h->nscount) : ntohs(h->arcount); | |
059ec3d9 PH |
399 | } |
400 | } | |
401 | ||
059ec3d9 PH |
402 | /* The variable dnss->aptr is now pointing at the next RR, and dnss->rrcount |
403 | contains the number of RR records left. */ | |
404 | ||
405 | if (dnss->rrcount-- <= 0) return NULL; | |
406 | ||
407 | /* If expanding the RR domain name fails, behave as if no more records | |
408 | (something safe). */ | |
409 | ||
410 | namelen = dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen, dnss->aptr, | |
411 | (DN_EXPAND_ARG4_TYPE) &(dnss->srr.name), DNS_MAXNAME); | |
412 | if (namelen < 0) { dnss->rrcount = 0; return NULL; } | |
413 | ||
414 | /* Move the pointer past the name and fill in the rest of the data structure | |
415 | from the following bytes. */ | |
416 | ||
417 | dnss->aptr += namelen; | |
418 | GETSHORT(dnss->srr.type, dnss->aptr); /* Record type */ | |
419 | dnss->aptr += 6; /* Don't want class or TTL */ | |
420 | GETSHORT(dnss->srr.size, dnss->aptr); /* Size of data portion */ | |
421 | dnss->srr.data = dnss->aptr; /* The record's data follows */ | |
422 | dnss->aptr += dnss->srr.size; /* Advance to next RR */ | |
423 | ||
424 | /* Return a pointer to the dns_record structure within the dns_answer. This is | |
425 | for convenience so that the scans can use nice-looking for loops. */ | |
426 | ||
427 | return &(dnss->srr); | |
428 | } | |
429 | ||
430 | ||
431 | ||
432 | ||
1f4a55da PP |
433 | /************************************************* |
434 | * Return whether AD bit set in DNS result * | |
435 | *************************************************/ | |
436 | ||
437 | /* We do not perform DNSSEC work ourselves; if the administrator has installed | |
438 | a verifying resolver which sets AD as appropriate, though, we'll use that. | |
439 | (AD = Authentic Data) | |
440 | ||
441 | Argument: pointer to dns answer block | |
442 | Returns: bool indicating presence of AD bit | |
443 | */ | |
444 | ||
445 | BOOL | |
4a142059 | 446 | dns_is_secure(const dns_answer * dnsa) |
1f4a55da PP |
447 | { |
448 | #ifdef DISABLE_DNSSEC | |
449 | DEBUG(D_dns) | |
450 | debug_printf("DNSSEC support disabled at build-time; dns_is_secure() false\n"); | |
451 | return FALSE; | |
452 | #else | |
453 | HEADER *h = (HEADER *)dnsa->answer; | |
454 | return h->ad ? TRUE : FALSE; | |
455 | #endif | |
456 | } | |
457 | ||
4a142059 JH |
458 | static void |
459 | dns_set_insecure(dns_answer * dnsa) | |
460 | { | |
461 | HEADER * h = (HEADER *)dnsa->answer; | |
462 | h->ad = 0; | |
463 | } | |
464 | ||
1f4a55da PP |
465 | |
466 | ||
467 | ||
059ec3d9 PH |
468 | /************************************************* |
469 | * Turn DNS type into text * | |
470 | *************************************************/ | |
471 | ||
885ccd3e PH |
472 | /* Turn the coded record type into a string for printing. All those that Exim |
473 | uses should be included here. | |
059ec3d9 PH |
474 | |
475 | Argument: record type | |
476 | Returns: pointer to string | |
477 | */ | |
478 | ||
479 | uschar * | |
480 | dns_text_type(int t) | |
481 | { | |
482 | switch(t) | |
483 | { | |
33397d19 PH |
484 | case T_A: return US"A"; |
485 | case T_MX: return US"MX"; | |
486 | case T_AAAA: return US"AAAA"; | |
487 | case T_A6: return US"A6"; | |
488 | case T_TXT: return US"TXT"; | |
eae0036b | 489 | case T_SPF: return US"SPF"; |
33397d19 | 490 | case T_PTR: return US"PTR"; |
885ccd3e | 491 | case T_SOA: return US"SOA"; |
33397d19 PH |
492 | case T_SRV: return US"SRV"; |
493 | case T_NS: return US"NS"; | |
8e669ac1 | 494 | case T_CNAME: return US"CNAME"; |
1e06383a | 495 | case T_TLSA: return US"TLSA"; |
33397d19 | 496 | default: return US"?"; |
059ec3d9 PH |
497 | } |
498 | } | |
499 | ||
500 | ||
501 | ||
502 | /************************************************* | |
503 | * Cache a failed DNS lookup result * | |
504 | *************************************************/ | |
505 | ||
506 | /* We cache failed lookup results so as not to experience timeouts many | |
507 | times for the same domain. We need to retain the resolver options because they | |
508 | may change. For successful lookups, we rely on resolver and/or name server | |
509 | caching. | |
510 | ||
511 | Arguments: | |
512 | name the domain name | |
513 | type the lookup type | |
514 | rc the return code | |
515 | ||
516 | Returns: the return code | |
517 | */ | |
518 | ||
519 | static int | |
1dc92d5a | 520 | dns_return(const uschar * name, int type, int rc) |
059ec3d9 | 521 | { |
5bfb4cdf | 522 | res_state resp = os_get_dns_resolver_res(); |
059ec3d9 PH |
523 | tree_node *node = store_get_perm(sizeof(tree_node) + 290); |
524 | sprintf(CS node->name, "%.255s-%s-%lx", name, dns_text_type(type), | |
5bfb4cdf | 525 | resp->options); |
059ec3d9 PH |
526 | node->data.val = rc; |
527 | (void)tree_insertnode(&tree_dns_fails, node); | |
528 | return rc; | |
529 | } | |
530 | ||
531 | ||
532 | ||
533 | /************************************************* | |
534 | * Do basic DNS lookup * | |
535 | *************************************************/ | |
536 | ||
537 | /* Call the resolver to look up the given domain name, using the given type, | |
538 | and check the result. The error code TRY_AGAIN is documented as meaning "non- | |
539 | Authoritive Host not found, or SERVERFAIL". Sometimes there are badly set | |
540 | up nameservers that produce this error continually, so there is the option of | |
541 | providing a list of domains for which this is treated as a non-existent | |
542 | host. | |
543 | ||
544 | Arguments: | |
545 | dnsa pointer to dns_answer structure | |
546 | name name to look up | |
547 | type type of DNS record required (T_A, T_MX, etc) | |
548 | ||
549 | Returns: DNS_SUCCEED successful lookup | |
550 | DNS_NOMATCH name not found (NXDOMAIN) | |
551 | or name contains illegal characters (if checking) | |
30e18802 | 552 | or name is an IP address (for IP address lookup) |
059ec3d9 PH |
553 | DNS_NODATA domain exists, but no data for this type (NODATA) |
554 | DNS_AGAIN soft failure, try again later | |
555 | DNS_FAIL DNS failure | |
556 | */ | |
557 | ||
558 | int | |
1dc92d5a | 559 | dns_basic_lookup(dns_answer *dnsa, const uschar *name, int type) |
059ec3d9 PH |
560 | { |
561 | #ifndef STAND_ALONE | |
7156b1ef | 562 | int rc = -1; |
55414b25 | 563 | const uschar *save_domain; |
059ec3d9 | 564 | #endif |
5bfb4cdf | 565 | res_state resp = os_get_dns_resolver_res(); |
059ec3d9 PH |
566 | |
567 | tree_node *previous; | |
568 | uschar node_name[290]; | |
569 | ||
570 | /* DNS lookup failures of any kind are cached in a tree. This is mainly so that | |
571 | a timeout on one domain doesn't happen time and time again for messages that | |
572 | have many addresses in the same domain. We rely on the resolver and name server | |
573 | caching for successful lookups. */ | |
574 | ||
575 | sprintf(CS node_name, "%.255s-%s-%lx", name, dns_text_type(type), | |
5bfb4cdf | 576 | resp->options); |
059ec3d9 PH |
577 | previous = tree_search(tree_dns_fails, node_name); |
578 | if (previous != NULL) | |
579 | { | |
580 | DEBUG(D_dns) debug_printf("DNS lookup of %.255s-%s: using cached value %s\n", | |
581 | name, dns_text_type(type), | |
582 | (previous->data.val == DNS_NOMATCH)? "DNS_NOMATCH" : | |
583 | (previous->data.val == DNS_NODATA)? "DNS_NODATA" : | |
584 | (previous->data.val == DNS_AGAIN)? "DNS_AGAIN" : | |
585 | (previous->data.val == DNS_FAIL)? "DNS_FAIL" : "??"); | |
586 | return previous->data.val; | |
587 | } | |
588 | ||
9d4319df JH |
589 | #ifdef EXPERIMENTAL_INTERNATIONAL |
590 | /* Convert all names to a-label form before doing lookup */ | |
591 | { | |
592 | uschar * alabel; | |
593 | uschar * errstr = NULL; | |
766e7a65 JH |
594 | DEBUG(D_dns) if (string_is_utf8(name)) |
595 | debug_printf("convert utf8 '%s' to alabel for for lookup\n", name); | |
9d4319df JH |
596 | if ((alabel = string_domain_utf8_to_alabel(name, &errstr)), errstr) |
597 | { | |
598 | DEBUG(D_dns) | |
37bf366e | 599 | debug_printf("DNS name '%s' utf8 conversion to alabel failed: %s\n", name, |
9d4319df JH |
600 | errstr); |
601 | host_find_failed_syntax = TRUE; | |
602 | return DNS_NOMATCH; | |
603 | } | |
604 | name = alabel; | |
605 | } | |
606 | #endif | |
607 | ||
059ec3d9 PH |
608 | /* If configured, check the hygene of the name passed to lookup. Otherwise, |
609 | although DNS lookups may give REFUSED at the lower level, some resolvers | |
610 | turn this into TRY_AGAIN, which is silly. Give a NOMATCH return, since such | |
611 | domains cannot be in the DNS. The check is now done by a regular expression; | |
612 | give it space for substring storage to save it having to get its own if the | |
613 | regex has substrings that are used - the default uses a conditional. | |
614 | ||
615 | This test is omitted for PTR records. These occur only in calls from the dnsdb | |
616 | lookup, which constructs the names itself, so they should be OK. Besides, | |
617 | bitstring labels don't conform to normal name syntax. (But the aren't used any | |
618 | more.) | |
619 | ||
620 | For SRV records, we omit the initial _smtp._tcp. components at the start. */ | |
621 | ||
622 | #ifndef STAND_ALONE /* Omit this for stand-alone tests */ | |
623 | ||
482d1455 | 624 | if (check_dns_names_pattern[0] != 0 && type != T_PTR && type != T_TXT) |
059ec3d9 | 625 | { |
1dc92d5a | 626 | const uschar *checkname = name; |
059ec3d9 PH |
627 | int ovector[3*(EXPAND_MAXN+1)]; |
628 | ||
476be7e2 | 629 | dns_pattern_init(); |
059ec3d9 PH |
630 | |
631 | /* For an SRV lookup, skip over the first two components (the service and | |
632 | protocol names, which both start with an underscore). */ | |
633 | ||
b4161d10 | 634 | if (type == T_SRV || type == T_TLSA) |
059ec3d9 PH |
635 | { |
636 | while (*checkname++ != '.'); | |
637 | while (*checkname++ != '.'); | |
638 | } | |
639 | ||
1dc92d5a | 640 | if (pcre_exec(regex_check_dns_names, NULL, CCS checkname, Ustrlen(checkname), |
059ec3d9 PH |
641 | 0, PCRE_EOPT, ovector, sizeof(ovector)/sizeof(int)) < 0) |
642 | { | |
643 | DEBUG(D_dns) | |
644 | debug_printf("DNS name syntax check failed: %s (%s)\n", name, | |
645 | dns_text_type(type)); | |
646 | host_find_failed_syntax = TRUE; | |
647 | return DNS_NOMATCH; | |
648 | } | |
649 | } | |
650 | ||
651 | #endif /* STAND_ALONE */ | |
652 | ||
653 | /* Call the resolver; for an overlong response, res_search() will return the | |
bef5a11f PH |
654 | number of bytes the message would need, so we need to check for this case. The |
655 | effect is to truncate overlong data. | |
656 | ||
30e18802 PH |
657 | On some systems, res_search() will recognize "A-for-A" queries and return |
658 | the IP address instead of returning -1 with h_error=HOST_NOT_FOUND. Some | |
659 | nameservers are also believed to do this. It is, of course, contrary to the | |
660 | specification of the DNS, so we lock it out. */ | |
661 | ||
cc00f4af | 662 | if ((type == T_A || type == T_AAAA) && string_is_ip_address(name, NULL) != 0) |
30e18802 PH |
663 | return DNS_NOMATCH; |
664 | ||
665 | /* If we are running in the test harness, instead of calling the normal resolver | |
bef5a11f PH |
666 | (res_search), we call fakens_search(), which recognizes certain special |
667 | domains, and interfaces to a fake nameserver for certain special zones. */ | |
668 | ||
cc00f4af JH |
669 | dnsa->answerlen = running_in_test_harness |
670 | ? fakens_search(name, type, dnsa->answer, MAXPACKET) | |
671 | : res_search(CCS name, C_IN, type, dnsa->answer, MAXPACKET); | |
059ec3d9 | 672 | |
80a47a2c TK |
673 | if (dnsa->answerlen > MAXPACKET) |
674 | { | |
675 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) resulted in overlong packet (size %d), truncating to %d.\n", | |
676 | name, dns_text_type(type), dnsa->answerlen, MAXPACKET); | |
677 | dnsa->answerlen = MAXPACKET; | |
678 | } | |
059ec3d9 PH |
679 | |
680 | if (dnsa->answerlen < 0) switch (h_errno) | |
681 | { | |
682 | case HOST_NOT_FOUND: | |
683 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave HOST_NOT_FOUND\n" | |
684 | "returning DNS_NOMATCH\n", name, dns_text_type(type)); | |
685 | return dns_return(name, type, DNS_NOMATCH); | |
686 | ||
687 | case TRY_AGAIN: | |
688 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave TRY_AGAIN\n", | |
689 | name, dns_text_type(type)); | |
690 | ||
691 | /* Cut this out for various test programs */ | |
1dc92d5a | 692 | #ifndef STAND_ALONE |
55414b25 | 693 | save_domain = deliver_domain; |
1dc92d5a | 694 | deliver_domain = string_copy(name); /* set $domain */ |
55414b25 | 695 | rc = match_isinlist(name, (const uschar **)&dns_again_means_nonexist, 0, NULL, NULL, |
059ec3d9 | 696 | MCL_DOMAIN, TRUE, NULL); |
55414b25 | 697 | deliver_domain = save_domain; |
059ec3d9 PH |
698 | if (rc != OK) |
699 | { | |
700 | DEBUG(D_dns) debug_printf("returning DNS_AGAIN\n"); | |
701 | return dns_return(name, type, DNS_AGAIN); | |
702 | } | |
703 | DEBUG(D_dns) debug_printf("%s is in dns_again_means_nonexist: returning " | |
704 | "DNS_NOMATCH\n", name); | |
705 | return dns_return(name, type, DNS_NOMATCH); | |
706 | ||
1dc92d5a | 707 | #else /* For stand-alone tests */ |
059ec3d9 | 708 | return dns_return(name, type, DNS_AGAIN); |
1dc92d5a | 709 | #endif |
059ec3d9 PH |
710 | |
711 | case NO_RECOVERY: | |
712 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave NO_RECOVERY\n" | |
713 | "returning DNS_FAIL\n", name, dns_text_type(type)); | |
714 | return dns_return(name, type, DNS_FAIL); | |
715 | ||
716 | case NO_DATA: | |
717 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave NO_DATA\n" | |
718 | "returning DNS_NODATA\n", name, dns_text_type(type)); | |
719 | return dns_return(name, type, DNS_NODATA); | |
720 | ||
721 | default: | |
722 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave unknown DNS error %d\n" | |
723 | "returning DNS_FAIL\n", name, dns_text_type(type), h_errno); | |
724 | return dns_return(name, type, DNS_FAIL); | |
725 | } | |
726 | ||
727 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) succeeded\n", | |
728 | name, dns_text_type(type)); | |
729 | ||
730 | return DNS_SUCCEED; | |
731 | } | |
732 | ||
733 | ||
734 | ||
735 | ||
736 | /************************************************ | |
737 | * Do a DNS lookup and handle CNAMES * | |
738 | ************************************************/ | |
739 | ||
740 | /* Look up the given domain name, using the given type. Follow CNAMEs if | |
741 | necessary, but only so many times. There aren't supposed to be CNAME chains in | |
742 | the DNS, but you are supposed to cope with them if you find them. | |
743 | ||
744 | The assumption is made that if the resolver gives back records of the | |
745 | requested type *and* a CNAME, we don't need to make another call to look up | |
746 | the CNAME. I can't see how it could return only some of the right records. If | |
747 | it's done a CNAME lookup in the past, it will have all of them; if not, it | |
748 | won't return any. | |
749 | ||
750 | If fully_qualified_name is not NULL, set it to point to the full name | |
751 | returned by the resolver, if this is different to what it is given, unless | |
752 | the returned name starts with "*" as some nameservers seem to be returning | |
766e7a65 JH |
753 | wildcards in this form. In international mode "different" means "alabel |
754 | forms are different". | |
059ec3d9 PH |
755 | |
756 | Arguments: | |
757 | dnsa pointer to dns_answer structure | |
758 | name domain name to look up | |
759 | type DNS record type (T_A, T_MX, etc) | |
760 | fully_qualified_name if not NULL, return the returned name here if its | |
761 | contents are different (i.e. it must be preset) | |
762 | ||
763 | Returns: DNS_SUCCEED successful lookup | |
764 | DNS_NOMATCH name not found | |
765 | DNS_NODATA no data found | |
766 | DNS_AGAIN soft failure, try again later | |
767 | DNS_FAIL DNS failure | |
768 | */ | |
769 | ||
770 | int | |
1dc92d5a | 771 | dns_lookup(dns_answer *dnsa, const uschar *name, int type, |
55414b25 | 772 | const uschar **fully_qualified_name) |
059ec3d9 PH |
773 | { |
774 | int i; | |
1dc92d5a | 775 | const uschar *orig_name = name; |
c85b3043 | 776 | BOOL secure_so_far = TRUE; |
059ec3d9 PH |
777 | |
778 | /* Loop to follow CNAME chains so far, but no further... */ | |
779 | ||
780 | for (i = 0; i < 10; i++) | |
781 | { | |
782 | uschar data[256]; | |
783 | dns_record *rr, cname_rr, type_rr; | |
784 | dns_scan dnss; | |
785 | int datalen, rc; | |
786 | ||
787 | /* DNS lookup failures get passed straight back. */ | |
788 | ||
789 | if ((rc = dns_basic_lookup(dnsa, name, type)) != DNS_SUCCEED) return rc; | |
790 | ||
791 | /* We should have either records of the required type, or a CNAME record, | |
792 | or both. We need to know whether both exist for getting the fully qualified | |
793 | name, but avoid scanning more than necessary. Note that we must copy the | |
794 | contents of any rr blocks returned by dns_next_rr() as they use the same | |
795 | area in the dnsa block. */ | |
796 | ||
797 | cname_rr.data = type_rr.data = NULL; | |
798 | for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); | |
799 | rr != NULL; | |
800 | rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)) | |
801 | { | |
802 | if (rr->type == type) | |
803 | { | |
804 | if (type_rr.data == NULL) type_rr = *rr; | |
805 | if (cname_rr.data != NULL) break; | |
806 | } | |
807 | else if (rr->type == T_CNAME) cname_rr = *rr; | |
808 | } | |
809 | ||
a2042e78 PH |
810 | /* For the first time round this loop, if a CNAME was found, take the fully |
811 | qualified name from it; otherwise from the first data record, if present. */ | |
059ec3d9 | 812 | |
a2042e78 | 813 | if (i == 0 && fully_qualified_name != NULL) |
059ec3d9 | 814 | { |
766e7a65 JH |
815 | uschar * rr_name = cname_rr.data ? cname_rr.name |
816 | : type_rr.data ? type_rr.name : NULL; | |
817 | if ( rr_name | |
818 | && Ustrcmp(rr_name, *fully_qualified_name) != 0 | |
819 | && rr_name[0] != '*' | |
820 | #ifdef EXPERIMENTAL_INTERNATIONAL | |
821 | && ( !string_is_utf8(*fully_qualified_name) | |
822 | || Ustrcmp(rr_name, | |
823 | string_domain_utf8_to_alabel(*fully_qualified_name, NULL)) != 0 | |
824 | ) | |
825 | #endif | |
826 | ) | |
827 | *fully_qualified_name = string_copy_dnsdomain(rr_name); | |
059ec3d9 PH |
828 | } |
829 | ||
830 | /* If any data records of the correct type were found, we are done. */ | |
831 | ||
c85b3043 JH |
832 | if (type_rr.data != NULL) |
833 | { | |
834 | if (!secure_so_far) /* mark insecure if any element of CNAME chain was */ | |
4a142059 | 835 | dns_set_insecure(dnsa); |
c85b3043 JH |
836 | return DNS_SUCCEED; |
837 | } | |
059ec3d9 PH |
838 | |
839 | /* If there are no data records, we need to re-scan the DNS using the | |
840 | domain given in the CNAME record, which should exist (otherwise we should | |
841 | have had a failure from dns_lookup). However code against the possibility of | |
842 | its not existing. */ | |
843 | ||
844 | if (cname_rr.data == NULL) return DNS_FAIL; | |
845 | datalen = dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen, | |
1dc92d5a | 846 | cname_rr.data, (DN_EXPAND_ARG4_TYPE)data, sizeof(data)); |
059ec3d9 PH |
847 | if (datalen < 0) return DNS_FAIL; |
848 | name = data; | |
a2042e78 | 849 | |
c85b3043 JH |
850 | if (!dns_is_secure(dnsa)) |
851 | secure_so_far = FALSE; | |
852 | ||
a2042e78 | 853 | DEBUG(D_dns) debug_printf("CNAME found: change to %s\n", name); |
059ec3d9 PH |
854 | } /* Loop back to do another lookup */ |
855 | ||
856 | /*Control reaches here after 10 times round the CNAME loop. Something isn't | |
857 | right... */ | |
858 | ||
859 | log_write(0, LOG_MAIN, "CNAME loop for %s encountered", orig_name); | |
860 | return DNS_FAIL; | |
861 | } | |
862 | ||
863 | ||
864 | ||
33397d19 PH |
865 | |
866 | ||
867 | ||
868 | /************************************************ | |
869 | * Do a DNS lookup and handle virtual types * | |
870 | ************************************************/ | |
871 | ||
8e669ac1 PH |
872 | /* This function handles some invented "lookup types" that synthesize feature |
873 | not available in the basic types. The special types all have negative values. | |
33397d19 PH |
874 | Positive type values are passed straight on to dns_lookup(). |
875 | ||
876 | Arguments: | |
877 | dnsa pointer to dns_answer structure | |
878 | name domain name to look up | |
879 | type DNS record type (T_A, T_MX, etc or a "special") | |
880 | fully_qualified_name if not NULL, return the returned name here if its | |
881 | contents are different (i.e. it must be preset) | |
882 | ||
883 | Returns: DNS_SUCCEED successful lookup | |
884 | DNS_NOMATCH name not found | |
885 | DNS_NODATA no data found | |
886 | DNS_AGAIN soft failure, try again later | |
887 | DNS_FAIL DNS failure | |
888 | */ | |
889 | ||
890 | int | |
1dc92d5a | 891 | dns_special_lookup(dns_answer *dnsa, const uschar *name, int type, |
55414b25 | 892 | const uschar **fully_qualified_name) |
33397d19 | 893 | { |
d2a2c69b | 894 | switch (type) |
e5a9dba6 | 895 | { |
d2a2c69b JH |
896 | /* The "mx hosts only" type doesn't require any special action here */ |
897 | case T_MXH: | |
898 | return dns_lookup(dnsa, name, T_MX, fully_qualified_name); | |
899 | ||
900 | /* Find nameservers for the domain or the nearest enclosing zone, excluding | |
901 | the root servers. */ | |
902 | case T_ZNS: | |
903 | type = T_NS; | |
904 | /* FALLTHROUGH */ | |
905 | case T_SOA: | |
906 | { | |
907 | const uschar *d = name; | |
908 | while (d != 0) | |
909 | { | |
910 | int rc = dns_lookup(dnsa, d, type, fully_qualified_name); | |
911 | if (rc != DNS_NOMATCH && rc != DNS_NODATA) return rc; | |
912 | while (*d != 0 && *d != '.') d++; | |
913 | if (*d++ == 0) break; | |
914 | } | |
915 | return DNS_NOMATCH; | |
916 | } | |
917 | ||
918 | /* Try to look up the Client SMTP Authorization SRV record for the name. If | |
919 | there isn't one, search from the top downwards for a CSA record in a parent | |
920 | domain, which might be making assertions about subdomains. If we find a record | |
921 | we set fully_qualified_name to whichever lookup succeeded, so that the caller | |
922 | can tell whether to look at the explicit authorization field or the subdomain | |
923 | assertion field. */ | |
924 | case T_CSA: | |
925 | { | |
926 | uschar *srvname, *namesuff, *tld, *p; | |
927 | int priority, weight, port; | |
928 | int limit, rc, i; | |
929 | BOOL ipv6; | |
930 | dns_record *rr; | |
931 | dns_scan dnss; | |
932 | ||
933 | DEBUG(D_dns) debug_printf("CSA lookup of %s\n", name); | |
934 | ||
935 | srvname = string_sprintf("_client._smtp.%s", name); | |
936 | rc = dns_lookup(dnsa, srvname, T_SRV, NULL); | |
937 | if (rc == DNS_SUCCEED || rc == DNS_AGAIN) | |
938 | { | |
939 | if (rc == DNS_SUCCEED) *fully_qualified_name = string_copy(name); | |
940 | return rc; | |
941 | } | |
942 | ||
943 | /* Search for CSA subdomain assertion SRV records from the top downwards, | |
944 | starting with the 2nd level domain. This order maximizes cache-friendliness. | |
945 | We skip the top level domains to avoid loading their nameservers and because | |
946 | we know they'll never have CSA SRV records. */ | |
947 | ||
948 | namesuff = Ustrrchr(name, '.'); | |
949 | if (namesuff == NULL) return DNS_NOMATCH; | |
950 | tld = namesuff + 1; | |
951 | ipv6 = FALSE; | |
952 | limit = dns_csa_search_limit; | |
953 | ||
954 | /* Use more appropriate search parameters if we are in the reverse DNS. */ | |
955 | ||
956 | if (strcmpic(namesuff, US".arpa") == 0) | |
957 | { | |
958 | if (namesuff - 8 > name && strcmpic(namesuff - 8, US".in-addr.arpa") == 0) | |
959 | { | |
960 | namesuff -= 8; | |
961 | tld = namesuff + 1; | |
962 | limit = 3; | |
963 | } | |
964 | else if (namesuff - 4 > name && strcmpic(namesuff - 4, US".ip6.arpa") == 0) | |
965 | { | |
966 | namesuff -= 4; | |
967 | tld = namesuff + 1; | |
968 | ipv6 = TRUE; | |
969 | limit = 3; | |
970 | } | |
971 | } | |
972 | ||
973 | DEBUG(D_dns) debug_printf("CSA TLD %s\n", tld); | |
974 | ||
975 | /* Do not perform the search if the top level or 2nd level domains do not | |
976 | exist. This is quite common, and when it occurs all the search queries would | |
977 | go to the root or TLD name servers, which is not friendly. So we check the | |
978 | AUTHORITY section; if it contains the root's SOA record or the TLD's SOA then | |
979 | the TLD or the 2LD (respectively) doesn't exist and we can skip the search. | |
980 | If the TLD and the 2LD exist but the explicit CSA record lookup failed, then | |
981 | the AUTHORITY SOA will be the 2LD's or a subdomain thereof. */ | |
982 | ||
983 | if (rc == DNS_NOMATCH) | |
984 | { | |
985 | /* This is really gross. The successful return value from res_search() is | |
986 | the packet length, which is stored in dnsa->answerlen. If we get a | |
987 | negative DNS reply then res_search() returns -1, which causes the bounds | |
988 | checks for name decompression to fail when it is treated as a packet | |
989 | length, which in turn causes the authority search to fail. The correct | |
990 | packet length has been lost inside libresolv, so we have to guess a | |
991 | replacement value. (The only way to fix this properly would be to | |
992 | re-implement res_search() and res_query() so that they don't muddle their | |
993 | success and packet length return values.) For added safety we only reset | |
994 | the packet length if the packet header looks plausible. */ | |
995 | ||
996 | HEADER *h = (HEADER *)dnsa->answer; | |
997 | if (h->qr == 1 && h->opcode == QUERY && h->tc == 0 | |
998 | && (h->rcode == NOERROR || h->rcode == NXDOMAIN) | |
999 | && ntohs(h->qdcount) == 1 && ntohs(h->ancount) == 0 | |
1000 | && ntohs(h->nscount) >= 1) | |
1001 | dnsa->answerlen = MAXPACKET; | |
1002 | ||
1003 | for (rr = dns_next_rr(dnsa, &dnss, RESET_AUTHORITY); | |
1004 | rr != NULL; | |
1005 | rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)) | |
1006 | if (rr->type != T_SOA) continue; | |
1007 | else if (strcmpic(rr->name, US"") == 0 || | |
1008 | strcmpic(rr->name, tld) == 0) return DNS_NOMATCH; | |
1009 | else break; | |
1010 | } | |
1011 | ||
1012 | for (i = 0; i < limit; i++) | |
1013 | { | |
1014 | if (ipv6) | |
1015 | { | |
1016 | /* Scan through the IPv6 reverse DNS in chunks of 16 bits worth of IP | |
1017 | address, i.e. 4 hex chars and 4 dots, i.e. 8 chars. */ | |
1018 | namesuff -= 8; | |
1019 | if (namesuff <= name) return DNS_NOMATCH; | |
1020 | } | |
1021 | else | |
1022 | /* Find the start of the preceding domain name label. */ | |
1023 | do | |
1024 | if (--namesuff <= name) return DNS_NOMATCH; | |
1025 | while (*namesuff != '.'); | |
1026 | ||
1027 | DEBUG(D_dns) debug_printf("CSA parent search at %s\n", namesuff + 1); | |
1028 | ||
1029 | srvname = string_sprintf("_client._smtp.%s", namesuff + 1); | |
1030 | rc = dns_lookup(dnsa, srvname, T_SRV, NULL); | |
1031 | if (rc == DNS_AGAIN) return rc; | |
1032 | if (rc != DNS_SUCCEED) continue; | |
1033 | ||
1034 | /* Check that the SRV record we have found is worth returning. We don't | |
1035 | just return the first one we find, because some lower level SRV record | |
1036 | might make stricter assertions than its parent domain. */ | |
1037 | ||
1038 | for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); | |
1039 | rr != NULL; | |
1040 | rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)) | |
1041 | { | |
1042 | if (rr->type != T_SRV) continue; | |
1043 | ||
1044 | /* Extract the numerical SRV fields (p is incremented) */ | |
1045 | p = rr->data; | |
1046 | GETSHORT(priority, p); | |
1047 | GETSHORT(weight, p); weight = weight; /* compiler quietening */ | |
1048 | GETSHORT(port, p); | |
1049 | ||
1050 | /* Check the CSA version number */ | |
1051 | if (priority != 1) continue; | |
1052 | ||
1053 | /* If it's making an interesting assertion, return this response. */ | |
1054 | if (port & 1) | |
1055 | { | |
1056 | *fully_qualified_name = namesuff + 1; | |
1057 | return DNS_SUCCEED; | |
1058 | } | |
1059 | } | |
1060 | } | |
1061 | return DNS_NOMATCH; | |
1062 | } | |
e5a9dba6 | 1063 | |
d2a2c69b JH |
1064 | default: |
1065 | if (type >= 0) | |
1066 | return dns_lookup(dnsa, name, type, fully_qualified_name); | |
e5a9dba6 PH |
1067 | } |
1068 | ||
33397d19 PH |
1069 | /* Control should never reach here */ |
1070 | ||
1071 | return DNS_FAIL; | |
1072 | } | |
1073 | ||
1074 | ||
1075 | ||
059ec3d9 PH |
1076 | |
1077 | ||
1078 | /************************************************* | |
1079 | * Get address(es) from DNS record * | |
1080 | *************************************************/ | |
1081 | ||
1082 | /* The record type is either T_A for an IPv4 address or T_AAAA (or T_A6 when | |
d2a2c69b | 1083 | supported) for an IPv6 address. |
059ec3d9 PH |
1084 | |
1085 | Argument: | |
1086 | dnsa the DNS answer block | |
1087 | rr the RR | |
1088 | ||
e1a3f32f | 1089 | Returns: pointer to a chain of dns_address items; NULL when the dnsa was overrun |
059ec3d9 PH |
1090 | */ |
1091 | ||
1092 | dns_address * | |
1093 | dns_address_from_rr(dns_answer *dnsa, dns_record *rr) | |
1094 | { | |
e1a3f32f JH |
1095 | dns_address * yield = NULL; |
1096 | uschar * dnsa_lim = dnsa->answer + dnsa->answerlen; | |
059ec3d9 PH |
1097 | |
1098 | if (rr->type == T_A) | |
1099 | { | |
d2a2c69b | 1100 | uschar *p = US rr->data; |
e1a3f32f JH |
1101 | if (p + 4 <= dnsa_lim) |
1102 | { | |
1103 | yield = store_get(sizeof(dns_address) + 20); | |
1104 | (void)sprintf(CS yield->address, "%d.%d.%d.%d", p[0], p[1], p[2], p[3]); | |
1105 | yield->next = NULL; | |
1106 | } | |
059ec3d9 PH |
1107 | } |
1108 | ||
1109 | #if HAVE_IPV6 | |
1110 | ||
059ec3d9 PH |
1111 | else |
1112 | { | |
e1a3f32f JH |
1113 | if (rr->data + 16 <= dnsa_lim) |
1114 | { | |
1115 | yield = store_get(sizeof(dns_address) + 50); | |
1116 | inet_ntop(AF_INET6, US rr->data, CS yield->address, 50); | |
1117 | yield->next = NULL; | |
1118 | } | |
059ec3d9 PH |
1119 | } |
1120 | #endif /* HAVE_IPV6 */ | |
1121 | ||
1122 | return yield; | |
1123 | } | |
1124 | ||
476be7e2 JH |
1125 | |
1126 | ||
1127 | void | |
1128 | dns_pattern_init(void) | |
1129 | { | |
1130 | if (check_dns_names_pattern[0] != 0 && !regex_check_dns_names) | |
1131 | regex_check_dns_names = | |
1132 | regex_must_compile(check_dns_names_pattern, FALSE, TRUE); | |
1133 | } | |
1134 | ||
8c51eead JH |
1135 | /* vi: aw ai sw=2 |
1136 | */ | |
059ec3d9 | 1137 | /* End of dns.c */ |