Commit | Line | Data |
---|---|---|
e7726cbf | 1 | /* $Cambridge: exim/src/src/dns.c,v 1.11 2005/09/16 14:44:11 ph10 Exp $ */ |
059ec3d9 PH |
2 | |
3 | /************************************************* | |
4 | * Exim - an Internet mail transport agent * | |
5 | *************************************************/ | |
6 | ||
c988f1f4 | 7 | /* Copyright (c) University of Cambridge 1995 - 2005 */ |
059ec3d9 PH |
8 | /* See the file NOTICE for conditions of use and distribution. */ |
9 | ||
10 | /* Functions for interfacing with the DNS. */ | |
11 | ||
12 | #include "exim.h" | |
13 | ||
14 | ||
15 | /* Function declaration needed for mutual recursion when A6 records | |
16 | are supported. */ | |
17 | ||
18 | #if HAVE_IPV6 | |
19 | #ifdef SUPPORT_A6 | |
20 | static void dns_complete_a6(dns_address ***, dns_answer *, dns_record *, | |
21 | int, uschar *); | |
22 | #endif | |
23 | #endif | |
24 | ||
25 | ||
bef5a11f PH |
26 | /************************************************* |
27 | * Fake DNS resolver * | |
28 | *************************************************/ | |
29 | ||
30 | /* This function is called instead of res_search() when Exim is running in its | |
31 | test harness. It recognizes some special domain names, and uses them to force | |
32 | failure and retry responses (optionally with a delay). It also recognises the | |
e7726cbf PH |
33 | zones test.ex, 10.in-addr.arpa, and 0.8.e.f.ip6.arpa, and for those it calls an |
34 | external utility that mock-up a nameserver, if it can find the utility. | |
35 | Otherwise, it passes its arguments on to res_search(). | |
bef5a11f PH |
36 | |
37 | Background: the original test suite required a real nameserver to carry the | |
e7726cbf PH |
38 | test zones, whereas the new test suit has the fake server for portability. This |
39 | code supports both. | |
bef5a11f PH |
40 | |
41 | Arguments: | |
e7726cbf | 42 | domain the domain name |
bef5a11f PH |
43 | type the DNS record type |
44 | answerptr where to put the answer | |
45 | size size of the answer area | |
46 | ||
47 | Returns: length of returned data, or -1 on error (h_errno set) | |
48 | */ | |
49 | ||
50 | static int | |
e7726cbf | 51 | fakens_search(uschar *domain, int type, uschar *answerptr, int size) |
bef5a11f | 52 | { |
e7726cbf PH |
53 | int len = Ustrlen(domain); |
54 | uschar *endname; | |
55 | uschar name[256]; | |
56 | ||
57 | if (domain[len - 1] == '.') len--; | |
58 | Ustrncpy(name, domain, len); | |
59 | name[len] = 0; | |
60 | endname = name + len; | |
bef5a11f PH |
61 | |
62 | if (len >= 14 && Ustrcmp(endname - 14, "test.again.dns") == 0) | |
63 | { | |
64 | int delay = Uatoi(name); /* digits at the start of the name */ | |
65 | DEBUG(D_dns) debug_printf("Return from DNS lookup of %s (%s) faked for testing\n", | |
66 | name, dns_text_type(type)); | |
67 | if (delay > 0) | |
68 | { | |
69 | DEBUG(D_dns) debug_printf("delaying %d seconds\n", delay); | |
70 | sleep(delay); | |
71 | } | |
72 | h_errno = TRY_AGAIN; | |
73 | return -1; | |
74 | } | |
75 | ||
76 | if (len >= 13 && Ustrcmp(endname - 13, "test.fail.dns") == 0) | |
77 | { | |
78 | DEBUG(D_dns) debug_printf("Return from DNS lookup of %s (%s) faked for testing\n", | |
79 | name, dns_text_type(type)); | |
80 | h_errno = NO_RECOVERY; | |
81 | return -1; | |
82 | } | |
83 | ||
84 | if (Ustrcmp(name, "test.ex") == 0 || | |
85 | (len > 8 && Ustrcmp(endname - 8, ".test.ex") == 0) || | |
e7726cbf PH |
86 | (len >= 16 && Ustrcmp(endname - 16, ".10.in-addr.arpa") == 0) || |
87 | (len >= 17 && Ustrcmp(endname - 17, ".0.8.e.f.ip6.arpa") == 0)) | |
bef5a11f PH |
88 | { |
89 | uschar utilname[256]; | |
90 | struct stat statbuf; | |
91 | ||
92 | (void)string_format(utilname, sizeof(utilname), "%s/../bin/fakens", | |
93 | spool_directory); | |
94 | ||
95 | if (stat(CS utilname, &statbuf) >= 0) | |
96 | { | |
97 | pid_t pid; | |
98 | int infd, outfd, rc; | |
99 | uschar *argv[5]; | |
100 | ||
101 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) using fakens\n", | |
102 | name, dns_text_type(type)); | |
103 | ||
104 | argv[0] = utilname; | |
105 | argv[1] = spool_directory; | |
106 | argv[2] = name; | |
107 | argv[3] = dns_text_type(type); | |
108 | argv[4] = NULL; | |
109 | ||
110 | pid = child_open(argv, NULL, 0000, &infd, &outfd, FALSE); | |
111 | if (pid < 0) | |
112 | log_write(0, LOG_MAIN|LOG_PANIC_DIE, "failed to run fakens: %s", | |
113 | strerror(errno)); | |
114 | ||
115 | len = 0; | |
116 | rc = -1; | |
117 | while (size > 0 && (rc = read(outfd, answerptr, size)) > 0) | |
118 | { | |
119 | len += rc; | |
120 | answerptr += rc; | |
121 | size -= rc; | |
122 | } | |
123 | ||
124 | if (rc < 0) | |
125 | log_write(0, LOG_MAIN|LOG_PANIC_DIE, "read from fakens failed: %s", | |
126 | strerror(errno)); | |
127 | ||
128 | switch(child_close(pid, 0)) | |
129 | { | |
130 | case 0: return len; | |
131 | case 1: h_errno = HOST_NOT_FOUND; break; | |
132 | case 2: h_errno = TRY_AGAIN; break; | |
133 | default: | |
134 | case 3: h_errno = NO_RECOVERY; break; | |
135 | case 4: h_errno = NO_DATA; break; | |
136 | } | |
137 | return -1; | |
138 | } | |
139 | } | |
140 | ||
141 | /* Not test.ex or 10.in-addr.arpa, or fakens utility not found. */ | |
142 | ||
e7726cbf PH |
143 | DEBUG(D_dns) debug_printf("passing %s on to res_search\n", domain); |
144 | ||
145 | return res_search(CS domain, C_IN, type, answerptr, size); | |
bef5a11f PH |
146 | } |
147 | ||
148 | ||
059ec3d9 PH |
149 | |
150 | /************************************************* | |
151 | * Initialize and configure resolver * | |
152 | *************************************************/ | |
153 | ||
154 | /* Initialize the resolver and the storage for holding DNS answers if this is | |
155 | the first time we have been here, and set the resolver options. | |
156 | ||
157 | Arguments: | |
158 | qualify_single TRUE to set the RES_DEFNAMES option | |
159 | search_parents TRUE to set the RES_DNSRCH option | |
160 | ||
161 | Returns: nothing | |
162 | */ | |
163 | ||
164 | void | |
165 | dns_init(BOOL qualify_single, BOOL search_parents) | |
166 | { | |
167 | if ((_res.options & RES_INIT) == 0) | |
168 | { | |
169 | DEBUG(D_resolver) _res.options |= RES_DEBUG; /* For Cygwin */ | |
170 | res_init(); | |
171 | DEBUG(D_resolver) _res.options |= RES_DEBUG; | |
172 | } | |
173 | ||
174 | _res.options &= ~(RES_DNSRCH | RES_DEFNAMES); | |
175 | _res.options |= (qualify_single? RES_DEFNAMES : 0) | | |
176 | (search_parents? RES_DNSRCH : 0); | |
177 | if (dns_retrans > 0) _res.retrans = dns_retrans; | |
178 | if (dns_retry > 0) _res.retry = dns_retry; | |
179 | } | |
180 | ||
181 | ||
182 | ||
183 | /************************************************* | |
184 | * Build key name for PTR records * | |
185 | *************************************************/ | |
186 | ||
187 | /* This function inverts an IP address and adds the relevant domain, to produce | |
188 | a name that can be used to look up PTR records. | |
189 | ||
190 | Arguments: | |
191 | string the IP address as a string | |
192 | buffer a suitable buffer, long enough to hold the result | |
193 | ||
194 | Returns: nothing | |
195 | */ | |
196 | ||
197 | void | |
198 | dns_build_reverse(uschar *string, uschar *buffer) | |
199 | { | |
200 | uschar *p = string + Ustrlen(string); | |
201 | uschar *pp = buffer; | |
202 | ||
203 | /* Handle IPv4 address */ | |
204 | ||
205 | #if HAVE_IPV6 | |
206 | if (Ustrchr(string, ':') == NULL) | |
207 | #endif | |
208 | { | |
209 | int i; | |
210 | for (i = 0; i < 4; i++) | |
211 | { | |
212 | uschar *ppp = p; | |
213 | while (ppp > string && ppp[-1] != '.') ppp--; | |
214 | Ustrncpy(pp, ppp, p - ppp); | |
215 | pp += p - ppp; | |
216 | *pp++ = '.'; | |
217 | p = ppp - 1; | |
218 | } | |
219 | Ustrcpy(pp, "in-addr.arpa"); | |
220 | } | |
221 | ||
222 | /* Handle IPv6 address; convert to binary so as to fill out any | |
223 | abbreviation in the textual form. */ | |
224 | ||
225 | #if HAVE_IPV6 | |
226 | else | |
227 | { | |
228 | int i; | |
229 | int v6[4]; | |
230 | (void)host_aton(string, v6); | |
231 | ||
232 | /* The original specification for IPv6 reverse lookup was to invert each | |
233 | nibble, and look in the ip6.int domain. The domain was subsequently | |
234 | changed to ip6.arpa. */ | |
235 | ||
236 | for (i = 3; i >= 0; i--) | |
237 | { | |
238 | int j; | |
239 | for (j = 0; j < 32; j += 4) | |
240 | { | |
241 | sprintf(CS pp, "%x.", (v6[i] >> j) & 15); | |
242 | pp += 2; | |
243 | } | |
244 | } | |
245 | Ustrcpy(pp, "ip6.arpa."); | |
246 | ||
247 | /* Another way of doing IPv6 reverse lookups was proposed in conjunction | |
248 | with A6 records. However, it fell out of favour when they did. The | |
249 | alternative was to construct a binary key, and look in ip6.arpa. I tried | |
250 | to make this code do that, but I could not make it work on Solaris 8. The | |
251 | resolver seems to lose the initial backslash somehow. However, now that | |
252 | this style of reverse lookup has been dropped, it doesn't matter. These | |
253 | lines are left here purely for historical interest. */ | |
254 | ||
255 | /************************************************** | |
256 | Ustrcpy(pp, "\\[x"); | |
257 | pp += 3; | |
258 | ||
259 | for (i = 0; i < 4; i++) | |
260 | { | |
261 | sprintf(pp, "%08X", v6[i]); | |
262 | pp += 8; | |
263 | } | |
264 | Ustrcpy(pp, "].ip6.arpa."); | |
265 | **************************************************/ | |
266 | ||
267 | } | |
268 | #endif | |
269 | } | |
270 | ||
271 | ||
272 | ||
273 | ||
274 | /************************************************* | |
275 | * Get next DNS record from answer block * | |
276 | *************************************************/ | |
277 | ||
278 | /* Call this with reset == RESET_ANSWERS to scan the answer block, reset == | |
e5a9dba6 PH |
279 | RESET_AUTHORITY to scan the authority records, reset == RESET_ADDITIONAL to |
280 | scan the additional records, and reset == RESET_NEXT to get the next record. | |
281 | The result is in static storage which must be copied if it is to be preserved. | |
059ec3d9 PH |
282 | |
283 | Arguments: | |
284 | dnsa pointer to dns answer block | |
285 | dnss pointer to dns scan block | |
286 | reset option specifing what portion to scan, as described above | |
287 | ||
288 | Returns: next dns record, or NULL when no more | |
289 | */ | |
290 | ||
291 | dns_record * | |
292 | dns_next_rr(dns_answer *dnsa, dns_scan *dnss, int reset) | |
293 | { | |
294 | HEADER *h = (HEADER *)dnsa->answer; | |
295 | int namelen; | |
296 | ||
297 | /* Reset the saved data when requested to, and skip to the first required RR */ | |
298 | ||
299 | if (reset != RESET_NEXT) | |
300 | { | |
301 | dnss->rrcount = ntohs(h->qdcount); | |
302 | dnss->aptr = dnsa->answer + sizeof(HEADER); | |
303 | ||
304 | /* Skip over questions; failure to expand the name just gives up */ | |
305 | ||
306 | while (dnss->rrcount-- > 0) | |
307 | { | |
308 | namelen = dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen, | |
309 | dnss->aptr, (DN_EXPAND_ARG4_TYPE) &(dnss->srr.name), DNS_MAXNAME); | |
310 | if (namelen < 0) { dnss->rrcount = 0; return NULL; } | |
311 | dnss->aptr += namelen + 4; /* skip name & type & class */ | |
312 | } | |
313 | ||
314 | /* Get the number of answer records. */ | |
315 | ||
316 | dnss->rrcount = ntohs(h->ancount); | |
317 | ||
e5a9dba6 PH |
318 | /* Skip over answers if we want to look at the authority section. Also skip |
319 | the NS records (i.e. authority section) if wanting to look at the additional | |
059ec3d9 PH |
320 | records. */ |
321 | ||
e5a9dba6 PH |
322 | if (reset == RESET_ADDITIONAL) dnss->rrcount += ntohs(h->nscount); |
323 | ||
324 | if (reset == RESET_AUTHORITY || reset == RESET_ADDITIONAL) | |
059ec3d9 | 325 | { |
059ec3d9 PH |
326 | while (dnss->rrcount-- > 0) |
327 | { | |
328 | namelen = dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen, | |
329 | dnss->aptr, (DN_EXPAND_ARG4_TYPE) &(dnss->srr.name), DNS_MAXNAME); | |
330 | if (namelen < 0) { dnss->rrcount = 0; return NULL; } | |
331 | dnss->aptr += namelen + 8; /* skip name, type, class & TTL */ | |
332 | GETSHORT(dnss->srr.size, dnss->aptr); /* size of data portion */ | |
333 | dnss->aptr += dnss->srr.size; /* skip over it */ | |
334 | } | |
e5a9dba6 PH |
335 | dnss->rrcount = (reset == RESET_AUTHORITY) |
336 | ? ntohs(h->nscount) : ntohs(h->arcount); | |
059ec3d9 PH |
337 | } |
338 | } | |
339 | ||
059ec3d9 PH |
340 | /* The variable dnss->aptr is now pointing at the next RR, and dnss->rrcount |
341 | contains the number of RR records left. */ | |
342 | ||
343 | if (dnss->rrcount-- <= 0) return NULL; | |
344 | ||
345 | /* If expanding the RR domain name fails, behave as if no more records | |
346 | (something safe). */ | |
347 | ||
348 | namelen = dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen, dnss->aptr, | |
349 | (DN_EXPAND_ARG4_TYPE) &(dnss->srr.name), DNS_MAXNAME); | |
350 | if (namelen < 0) { dnss->rrcount = 0; return NULL; } | |
351 | ||
352 | /* Move the pointer past the name and fill in the rest of the data structure | |
353 | from the following bytes. */ | |
354 | ||
355 | dnss->aptr += namelen; | |
356 | GETSHORT(dnss->srr.type, dnss->aptr); /* Record type */ | |
357 | dnss->aptr += 6; /* Don't want class or TTL */ | |
358 | GETSHORT(dnss->srr.size, dnss->aptr); /* Size of data portion */ | |
359 | dnss->srr.data = dnss->aptr; /* The record's data follows */ | |
360 | dnss->aptr += dnss->srr.size; /* Advance to next RR */ | |
361 | ||
362 | /* Return a pointer to the dns_record structure within the dns_answer. This is | |
363 | for convenience so that the scans can use nice-looking for loops. */ | |
364 | ||
365 | return &(dnss->srr); | |
366 | } | |
367 | ||
368 | ||
369 | ||
370 | ||
371 | /************************************************* | |
372 | * Turn DNS type into text * | |
373 | *************************************************/ | |
374 | ||
885ccd3e PH |
375 | /* Turn the coded record type into a string for printing. All those that Exim |
376 | uses should be included here. | |
059ec3d9 PH |
377 | |
378 | Argument: record type | |
379 | Returns: pointer to string | |
380 | */ | |
381 | ||
382 | uschar * | |
383 | dns_text_type(int t) | |
384 | { | |
385 | switch(t) | |
386 | { | |
33397d19 PH |
387 | case T_A: return US"A"; |
388 | case T_MX: return US"MX"; | |
389 | case T_AAAA: return US"AAAA"; | |
390 | case T_A6: return US"A6"; | |
391 | case T_TXT: return US"TXT"; | |
392 | case T_PTR: return US"PTR"; | |
885ccd3e | 393 | case T_SOA: return US"SOA"; |
33397d19 PH |
394 | case T_SRV: return US"SRV"; |
395 | case T_NS: return US"NS"; | |
8e669ac1 | 396 | case T_CNAME: return US"CNAME"; |
33397d19 | 397 | default: return US"?"; |
059ec3d9 PH |
398 | } |
399 | } | |
400 | ||
401 | ||
402 | ||
403 | /************************************************* | |
404 | * Cache a failed DNS lookup result * | |
405 | *************************************************/ | |
406 | ||
407 | /* We cache failed lookup results so as not to experience timeouts many | |
408 | times for the same domain. We need to retain the resolver options because they | |
409 | may change. For successful lookups, we rely on resolver and/or name server | |
410 | caching. | |
411 | ||
412 | Arguments: | |
413 | name the domain name | |
414 | type the lookup type | |
415 | rc the return code | |
416 | ||
417 | Returns: the return code | |
418 | */ | |
419 | ||
420 | static int | |
421 | dns_return(uschar *name, int type, int rc) | |
422 | { | |
423 | tree_node *node = store_get_perm(sizeof(tree_node) + 290); | |
424 | sprintf(CS node->name, "%.255s-%s-%lx", name, dns_text_type(type), | |
425 | _res.options); | |
426 | node->data.val = rc; | |
427 | (void)tree_insertnode(&tree_dns_fails, node); | |
428 | return rc; | |
429 | } | |
430 | ||
431 | ||
432 | ||
433 | /************************************************* | |
434 | * Do basic DNS lookup * | |
435 | *************************************************/ | |
436 | ||
437 | /* Call the resolver to look up the given domain name, using the given type, | |
438 | and check the result. The error code TRY_AGAIN is documented as meaning "non- | |
439 | Authoritive Host not found, or SERVERFAIL". Sometimes there are badly set | |
440 | up nameservers that produce this error continually, so there is the option of | |
441 | providing a list of domains for which this is treated as a non-existent | |
442 | host. | |
443 | ||
444 | Arguments: | |
445 | dnsa pointer to dns_answer structure | |
446 | name name to look up | |
447 | type type of DNS record required (T_A, T_MX, etc) | |
448 | ||
449 | Returns: DNS_SUCCEED successful lookup | |
450 | DNS_NOMATCH name not found (NXDOMAIN) | |
451 | or name contains illegal characters (if checking) | |
452 | DNS_NODATA domain exists, but no data for this type (NODATA) | |
453 | DNS_AGAIN soft failure, try again later | |
454 | DNS_FAIL DNS failure | |
455 | */ | |
456 | ||
457 | int | |
458 | dns_basic_lookup(dns_answer *dnsa, uschar *name, int type) | |
459 | { | |
bef5a11f | 460 | int rc = -1; |
059ec3d9 | 461 | #ifndef STAND_ALONE |
059ec3d9 PH |
462 | uschar *save; |
463 | #endif | |
464 | ||
465 | tree_node *previous; | |
466 | uschar node_name[290]; | |
467 | ||
468 | /* DNS lookup failures of any kind are cached in a tree. This is mainly so that | |
469 | a timeout on one domain doesn't happen time and time again for messages that | |
470 | have many addresses in the same domain. We rely on the resolver and name server | |
471 | caching for successful lookups. */ | |
472 | ||
473 | sprintf(CS node_name, "%.255s-%s-%lx", name, dns_text_type(type), | |
474 | _res.options); | |
475 | previous = tree_search(tree_dns_fails, node_name); | |
476 | if (previous != NULL) | |
477 | { | |
478 | DEBUG(D_dns) debug_printf("DNS lookup of %.255s-%s: using cached value %s\n", | |
479 | name, dns_text_type(type), | |
480 | (previous->data.val == DNS_NOMATCH)? "DNS_NOMATCH" : | |
481 | (previous->data.val == DNS_NODATA)? "DNS_NODATA" : | |
482 | (previous->data.val == DNS_AGAIN)? "DNS_AGAIN" : | |
483 | (previous->data.val == DNS_FAIL)? "DNS_FAIL" : "??"); | |
484 | return previous->data.val; | |
485 | } | |
486 | ||
059ec3d9 PH |
487 | /* If configured, check the hygene of the name passed to lookup. Otherwise, |
488 | although DNS lookups may give REFUSED at the lower level, some resolvers | |
489 | turn this into TRY_AGAIN, which is silly. Give a NOMATCH return, since such | |
490 | domains cannot be in the DNS. The check is now done by a regular expression; | |
491 | give it space for substring storage to save it having to get its own if the | |
492 | regex has substrings that are used - the default uses a conditional. | |
493 | ||
494 | This test is omitted for PTR records. These occur only in calls from the dnsdb | |
495 | lookup, which constructs the names itself, so they should be OK. Besides, | |
496 | bitstring labels don't conform to normal name syntax. (But the aren't used any | |
497 | more.) | |
498 | ||
499 | For SRV records, we omit the initial _smtp._tcp. components at the start. */ | |
500 | ||
501 | #ifndef STAND_ALONE /* Omit this for stand-alone tests */ | |
502 | ||
503 | if (check_dns_names_pattern[0] != 0 && type != T_PTR) | |
504 | { | |
505 | uschar *checkname = name; | |
506 | int ovector[3*(EXPAND_MAXN+1)]; | |
507 | ||
508 | if (regex_check_dns_names == NULL) | |
509 | regex_check_dns_names = | |
510 | regex_must_compile(check_dns_names_pattern, FALSE, TRUE); | |
511 | ||
512 | /* For an SRV lookup, skip over the first two components (the service and | |
513 | protocol names, which both start with an underscore). */ | |
514 | ||
515 | if (type == T_SRV) | |
516 | { | |
517 | while (*checkname++ != '.'); | |
518 | while (*checkname++ != '.'); | |
519 | } | |
520 | ||
521 | if (pcre_exec(regex_check_dns_names, NULL, CS checkname, Ustrlen(checkname), | |
522 | 0, PCRE_EOPT, ovector, sizeof(ovector)/sizeof(int)) < 0) | |
523 | { | |
524 | DEBUG(D_dns) | |
525 | debug_printf("DNS name syntax check failed: %s (%s)\n", name, | |
526 | dns_text_type(type)); | |
527 | host_find_failed_syntax = TRUE; | |
528 | return DNS_NOMATCH; | |
529 | } | |
530 | } | |
531 | ||
532 | #endif /* STAND_ALONE */ | |
533 | ||
534 | /* Call the resolver; for an overlong response, res_search() will return the | |
bef5a11f PH |
535 | number of bytes the message would need, so we need to check for this case. The |
536 | effect is to truncate overlong data. | |
537 | ||
538 | If we are running in the test harness, instead of calling the normal resolver | |
539 | (res_search), we call fakens_search(), which recognizes certain special | |
540 | domains, and interfaces to a fake nameserver for certain special zones. */ | |
541 | ||
542 | if (running_in_test_harness) | |
543 | dnsa->answerlen = fakens_search(name, type, dnsa->answer, MAXPACKET); | |
544 | else | |
545 | dnsa->answerlen = res_search(CS name, C_IN, type, dnsa->answer, MAXPACKET); | |
059ec3d9 | 546 | |
059ec3d9 PH |
547 | if (dnsa->answerlen > MAXPACKET) dnsa->answerlen = MAXPACKET; |
548 | ||
549 | if (dnsa->answerlen < 0) switch (h_errno) | |
550 | { | |
551 | case HOST_NOT_FOUND: | |
552 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave HOST_NOT_FOUND\n" | |
553 | "returning DNS_NOMATCH\n", name, dns_text_type(type)); | |
554 | return dns_return(name, type, DNS_NOMATCH); | |
555 | ||
556 | case TRY_AGAIN: | |
557 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave TRY_AGAIN\n", | |
558 | name, dns_text_type(type)); | |
559 | ||
560 | /* Cut this out for various test programs */ | |
561 | #ifndef STAND_ALONE | |
562 | save = deliver_domain; | |
563 | deliver_domain = name; /* set $domain */ | |
564 | rc = match_isinlist(name, &dns_again_means_nonexist, 0, NULL, NULL, | |
565 | MCL_DOMAIN, TRUE, NULL); | |
566 | deliver_domain = save; | |
567 | if (rc != OK) | |
568 | { | |
569 | DEBUG(D_dns) debug_printf("returning DNS_AGAIN\n"); | |
570 | return dns_return(name, type, DNS_AGAIN); | |
571 | } | |
572 | DEBUG(D_dns) debug_printf("%s is in dns_again_means_nonexist: returning " | |
573 | "DNS_NOMATCH\n", name); | |
574 | return dns_return(name, type, DNS_NOMATCH); | |
575 | ||
576 | #else /* For stand-alone tests */ | |
577 | return dns_return(name, type, DNS_AGAIN); | |
578 | #endif | |
579 | ||
580 | case NO_RECOVERY: | |
581 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave NO_RECOVERY\n" | |
582 | "returning DNS_FAIL\n", name, dns_text_type(type)); | |
583 | return dns_return(name, type, DNS_FAIL); | |
584 | ||
585 | case NO_DATA: | |
586 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave NO_DATA\n" | |
587 | "returning DNS_NODATA\n", name, dns_text_type(type)); | |
588 | return dns_return(name, type, DNS_NODATA); | |
589 | ||
590 | default: | |
591 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave unknown DNS error %d\n" | |
592 | "returning DNS_FAIL\n", name, dns_text_type(type), h_errno); | |
593 | return dns_return(name, type, DNS_FAIL); | |
594 | } | |
595 | ||
596 | DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) succeeded\n", | |
597 | name, dns_text_type(type)); | |
598 | ||
599 | return DNS_SUCCEED; | |
600 | } | |
601 | ||
602 | ||
603 | ||
604 | ||
605 | /************************************************ | |
606 | * Do a DNS lookup and handle CNAMES * | |
607 | ************************************************/ | |
608 | ||
609 | /* Look up the given domain name, using the given type. Follow CNAMEs if | |
610 | necessary, but only so many times. There aren't supposed to be CNAME chains in | |
611 | the DNS, but you are supposed to cope with them if you find them. | |
612 | ||
613 | The assumption is made that if the resolver gives back records of the | |
614 | requested type *and* a CNAME, we don't need to make another call to look up | |
615 | the CNAME. I can't see how it could return only some of the right records. If | |
616 | it's done a CNAME lookup in the past, it will have all of them; if not, it | |
617 | won't return any. | |
618 | ||
619 | If fully_qualified_name is not NULL, set it to point to the full name | |
620 | returned by the resolver, if this is different to what it is given, unless | |
621 | the returned name starts with "*" as some nameservers seem to be returning | |
622 | wildcards in this form. | |
623 | ||
624 | Arguments: | |
625 | dnsa pointer to dns_answer structure | |
626 | name domain name to look up | |
627 | type DNS record type (T_A, T_MX, etc) | |
628 | fully_qualified_name if not NULL, return the returned name here if its | |
629 | contents are different (i.e. it must be preset) | |
630 | ||
631 | Returns: DNS_SUCCEED successful lookup | |
632 | DNS_NOMATCH name not found | |
633 | DNS_NODATA no data found | |
634 | DNS_AGAIN soft failure, try again later | |
635 | DNS_FAIL DNS failure | |
636 | */ | |
637 | ||
638 | int | |
639 | dns_lookup(dns_answer *dnsa, uschar *name, int type, uschar **fully_qualified_name) | |
640 | { | |
641 | int i; | |
642 | uschar *orig_name = name; | |
643 | ||
644 | /* Loop to follow CNAME chains so far, but no further... */ | |
645 | ||
646 | for (i = 0; i < 10; i++) | |
647 | { | |
648 | uschar data[256]; | |
649 | dns_record *rr, cname_rr, type_rr; | |
650 | dns_scan dnss; | |
651 | int datalen, rc; | |
652 | ||
653 | /* DNS lookup failures get passed straight back. */ | |
654 | ||
655 | if ((rc = dns_basic_lookup(dnsa, name, type)) != DNS_SUCCEED) return rc; | |
656 | ||
657 | /* We should have either records of the required type, or a CNAME record, | |
658 | or both. We need to know whether both exist for getting the fully qualified | |
659 | name, but avoid scanning more than necessary. Note that we must copy the | |
660 | contents of any rr blocks returned by dns_next_rr() as they use the same | |
661 | area in the dnsa block. */ | |
662 | ||
663 | cname_rr.data = type_rr.data = NULL; | |
664 | for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); | |
665 | rr != NULL; | |
666 | rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)) | |
667 | { | |
668 | if (rr->type == type) | |
669 | { | |
670 | if (type_rr.data == NULL) type_rr = *rr; | |
671 | if (cname_rr.data != NULL) break; | |
672 | } | |
673 | else if (rr->type == T_CNAME) cname_rr = *rr; | |
674 | } | |
675 | ||
676 | /* If a CNAME was found, take the fully qualified name from it; otherwise | |
677 | from the first data record, if present. For testing, there is a magic name | |
678 | that gets its casing adjusted, because my resolver doesn't seem to pass back | |
679 | upper case letters in domain names. */ | |
680 | ||
681 | if (fully_qualified_name != NULL) | |
682 | { | |
683 | if (cname_rr.data != NULL) | |
684 | { | |
685 | if (Ustrcmp(cname_rr.name, *fully_qualified_name) != 0 && | |
686 | cname_rr.name[0] != '*') | |
687 | *fully_qualified_name = string_copy_dnsdomain(cname_rr.name); | |
688 | } | |
689 | else if (type_rr.data != NULL) | |
690 | { | |
691 | if (running_in_test_harness && | |
692 | Ustrcmp(type_rr.name, "uppercase.test.ex") == 0) | |
693 | *fully_qualified_name = US"UpperCase.test.ex"; | |
694 | else | |
695 | { | |
696 | if (Ustrcmp(type_rr.name, *fully_qualified_name) != 0 && | |
697 | type_rr.name[0] != '*') | |
698 | *fully_qualified_name = string_copy_dnsdomain(type_rr.name); | |
699 | } | |
700 | } | |
701 | } | |
702 | ||
703 | /* If any data records of the correct type were found, we are done. */ | |
704 | ||
705 | if (type_rr.data != NULL) return DNS_SUCCEED; | |
706 | ||
707 | /* If there are no data records, we need to re-scan the DNS using the | |
708 | domain given in the CNAME record, which should exist (otherwise we should | |
709 | have had a failure from dns_lookup). However code against the possibility of | |
710 | its not existing. */ | |
711 | ||
712 | if (cname_rr.data == NULL) return DNS_FAIL; | |
713 | datalen = dn_expand(dnsa->answer, dnsa->answer + dnsa->answerlen, | |
714 | cname_rr.data, (DN_EXPAND_ARG4_TYPE)data, 256); | |
715 | if (datalen < 0) return DNS_FAIL; | |
716 | name = data; | |
717 | } /* Loop back to do another lookup */ | |
718 | ||
719 | /*Control reaches here after 10 times round the CNAME loop. Something isn't | |
720 | right... */ | |
721 | ||
722 | log_write(0, LOG_MAIN, "CNAME loop for %s encountered", orig_name); | |
723 | return DNS_FAIL; | |
724 | } | |
725 | ||
726 | ||
727 | ||
33397d19 PH |
728 | |
729 | ||
730 | ||
731 | /************************************************ | |
732 | * Do a DNS lookup and handle virtual types * | |
733 | ************************************************/ | |
734 | ||
8e669ac1 PH |
735 | /* This function handles some invented "lookup types" that synthesize feature |
736 | not available in the basic types. The special types all have negative values. | |
33397d19 PH |
737 | Positive type values are passed straight on to dns_lookup(). |
738 | ||
739 | Arguments: | |
740 | dnsa pointer to dns_answer structure | |
741 | name domain name to look up | |
742 | type DNS record type (T_A, T_MX, etc or a "special") | |
743 | fully_qualified_name if not NULL, return the returned name here if its | |
744 | contents are different (i.e. it must be preset) | |
745 | ||
746 | Returns: DNS_SUCCEED successful lookup | |
747 | DNS_NOMATCH name not found | |
748 | DNS_NODATA no data found | |
749 | DNS_AGAIN soft failure, try again later | |
750 | DNS_FAIL DNS failure | |
751 | */ | |
752 | ||
753 | int | |
8e669ac1 | 754 | dns_special_lookup(dns_answer *dnsa, uschar *name, int type, |
33397d19 PH |
755 | uschar **fully_qualified_name) |
756 | { | |
757 | if (type >= 0) return dns_lookup(dnsa, name, type, fully_qualified_name); | |
758 | ||
ea3bc19b PH |
759 | /* The "mx hosts only" type doesn't require any special action here */ |
760 | ||
761 | if (type == T_MXH) return dns_lookup(dnsa, name, T_MX, fully_qualified_name); | |
762 | ||
8e669ac1 | 763 | /* Find nameservers for the domain or the nearest enclosing zone, excluding the |
33397d19 PH |
764 | root servers. */ |
765 | ||
766 | if (type == T_ZNS) | |
767 | { | |
768 | uschar *d = name; | |
769 | while (d != 0) | |
770 | { | |
771 | int rc = dns_lookup(dnsa, d, T_NS, fully_qualified_name); | |
772 | if (rc != DNS_NOMATCH && rc != DNS_NODATA) return rc; | |
773 | while (*d != 0 && *d != '.') d++; | |
8e669ac1 | 774 | if (*d++ == 0) break; |
33397d19 | 775 | } |
8e669ac1 PH |
776 | return DNS_NOMATCH; |
777 | } | |
33397d19 | 778 | |
e5a9dba6 PH |
779 | /* Try to look up the Client SMTP Authorization SRV record for the name. If |
780 | there isn't one, search from the top downwards for a CSA record in a parent | |
781 | domain, which might be making assertions about subdomains. If we find a record | |
782 | we set fully_qualified_name to whichever lookup succeeded, so that the caller | |
783 | can tell whether to look at the explicit authorization field or the subdomain | |
784 | assertion field. */ | |
785 | ||
786 | if (type == T_CSA) | |
787 | { | |
788 | uschar *srvname, *namesuff, *tld, *p; | |
789 | int priority, weight, port; | |
790 | int limit, rc, i; | |
791 | BOOL ipv6; | |
792 | dns_record *rr; | |
793 | dns_scan dnss; | |
794 | ||
795 | DEBUG(D_dns) debug_printf("CSA lookup of %s\n", name); | |
796 | ||
797 | srvname = string_sprintf("_client._smtp.%s", name); | |
798 | rc = dns_lookup(dnsa, srvname, T_SRV, NULL); | |
799 | if (rc == DNS_SUCCEED || rc == DNS_AGAIN) | |
800 | { | |
801 | if (rc == DNS_SUCCEED) *fully_qualified_name = name; | |
802 | return rc; | |
803 | } | |
804 | ||
805 | /* Search for CSA subdomain assertion SRV records from the top downwards, | |
806 | starting with the 2nd level domain. This order maximizes cache-friendliness. | |
807 | We skip the top level domains to avoid loading their nameservers and because | |
808 | we know they'll never have CSA SRV records. */ | |
809 | ||
810 | namesuff = Ustrrchr(name, '.'); | |
811 | if (namesuff == NULL) return DNS_NOMATCH; | |
812 | tld = namesuff + 1; | |
813 | ipv6 = FALSE; | |
814 | limit = dns_csa_search_limit; | |
815 | ||
816 | /* Use more appropriate search parameters if we are in the reverse DNS. */ | |
817 | ||
818 | if (strcmpic(namesuff, US".arpa") == 0) | |
819 | { | |
820 | if (namesuff - 8 > name && strcmpic(namesuff - 8, US".in-addr.arpa") == 0) | |
821 | { | |
822 | namesuff -= 8; | |
823 | tld = namesuff + 1; | |
824 | limit = 3; | |
825 | } | |
826 | else if (namesuff - 4 > name && strcmpic(namesuff - 4, US".ip6.arpa") == 0) | |
827 | { | |
828 | namesuff -= 4; | |
829 | tld = namesuff + 1; | |
830 | ipv6 = TRUE; | |
831 | limit = 3; | |
832 | } | |
833 | } | |
834 | ||
835 | DEBUG(D_dns) debug_printf("CSA TLD %s\n", tld); | |
836 | ||
837 | /* Do not perform the search if the top level or 2nd level domains do not | |
838 | exist. This is quite common, and when it occurs all the search queries would | |
839 | go to the root or TLD name servers, which is not friendly. So we check the | |
840 | AUTHORITY section; if it contains the root's SOA record or the TLD's SOA then | |
841 | the TLD or the 2LD (respectively) doesn't exist and we can skip the search. | |
842 | If the TLD and the 2LD exist but the explicit CSA record lookup failed, then | |
843 | the AUTHORITY SOA will be the 2LD's or a subdomain thereof. */ | |
844 | ||
845 | if (rc == DNS_NOMATCH) | |
846 | { | |
847 | /* This is really gross. The successful return value from res_search() is | |
848 | the packet length, which is stored in dnsa->answerlen. If we get a | |
849 | negative DNS reply then res_search() returns -1, which causes the bounds | |
850 | checks for name decompression to fail when it is treated as a packet | |
851 | length, which in turn causes the authority search to fail. The correct | |
852 | packet length has been lost inside libresolv, so we have to guess a | |
853 | replacement value. (The only way to fix this properly would be to | |
854 | re-implement res_search() and res_query() so that they don't muddle their | |
855 | success and packet length return values.) For added safety we only reset | |
856 | the packet length if the packet header looks plausible. */ | |
857 | ||
858 | HEADER *h = (HEADER *)dnsa->answer; | |
859 | if (h->qr == 1 && h->opcode == QUERY && h->tc == 0 | |
860 | && (h->rcode == NOERROR || h->rcode == NXDOMAIN) | |
861 | && ntohs(h->qdcount) == 1 && ntohs(h->ancount) == 0 | |
862 | && ntohs(h->nscount) >= 1) | |
863 | dnsa->answerlen = MAXPACKET; | |
864 | ||
865 | for (rr = dns_next_rr(dnsa, &dnss, RESET_AUTHORITY); | |
866 | rr != NULL; | |
867 | rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)) | |
868 | if (rr->type != T_SOA) continue; | |
869 | else if (strcmpic(rr->name, US"") == 0 || | |
870 | strcmpic(rr->name, tld) == 0) return DNS_NOMATCH; | |
871 | else break; | |
872 | } | |
873 | ||
874 | for (i = 0; i < limit; i++) | |
875 | { | |
876 | if (ipv6) | |
877 | { | |
878 | /* Scan through the IPv6 reverse DNS in chunks of 16 bits worth of IP | |
879 | address, i.e. 4 hex chars and 4 dots, i.e. 8 chars. */ | |
880 | namesuff -= 8; | |
881 | if (namesuff <= name) return DNS_NOMATCH; | |
882 | } | |
883 | else | |
884 | /* Find the start of the preceding domain name label. */ | |
885 | do | |
886 | if (--namesuff <= name) return DNS_NOMATCH; | |
887 | while (*namesuff != '.'); | |
888 | ||
889 | DEBUG(D_dns) debug_printf("CSA parent search at %s\n", namesuff + 1); | |
890 | ||
891 | srvname = string_sprintf("_client._smtp.%s", namesuff + 1); | |
892 | rc = dns_lookup(dnsa, srvname, T_SRV, NULL); | |
893 | if (rc == DNS_AGAIN) return rc; | |
894 | if (rc != DNS_SUCCEED) continue; | |
895 | ||
896 | /* Check that the SRV record we have found is worth returning. We don't | |
897 | just return the first one we find, because some lower level SRV record | |
898 | might make stricter assertions than its parent domain. */ | |
899 | ||
900 | for (rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); | |
901 | rr != NULL; | |
902 | rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)) | |
903 | { | |
904 | if (rr->type != T_SRV) continue; | |
905 | ||
906 | /* Extract the numerical SRV fields (p is incremented) */ | |
907 | p = rr->data; | |
908 | GETSHORT(priority, p); | |
909 | GETSHORT(weight, p); | |
910 | GETSHORT(port, p); | |
911 | ||
912 | /* Check the CSA version number */ | |
913 | if (priority != 1) continue; | |
914 | ||
915 | /* If it's making an interesting assertion, return this response. */ | |
916 | if (port & 1) | |
917 | { | |
918 | *fully_qualified_name = namesuff + 1; | |
919 | return DNS_SUCCEED; | |
920 | } | |
921 | } | |
922 | } | |
923 | return DNS_NOMATCH; | |
924 | } | |
925 | ||
33397d19 PH |
926 | /* Control should never reach here */ |
927 | ||
928 | return DNS_FAIL; | |
929 | } | |
930 | ||
931 | ||
932 | ||
059ec3d9 PH |
933 | /* Support for A6 records has been commented out since they were demoted to |
934 | experimental status at IETF 51. */ | |
935 | ||
936 | #if HAVE_IPV6 && defined(SUPPORT_A6) | |
937 | ||
938 | /************************************************* | |
939 | * Search DNS block for prefix RRs * | |
940 | *************************************************/ | |
941 | ||
942 | /* Called from dns_complete_a6() to search an additional section or a main | |
943 | answer section for required prefix records to complete an IPv6 address obtained | |
944 | from an A6 record. For each prefix record, a recursive call to dns_complete_a6 | |
945 | is made, with a new copy of the address so far. | |
946 | ||
947 | Arguments: | |
948 | dnsa the DNS answer block | |
949 | which RESET_ADDITIONAL or RESET_ANSWERS | |
950 | name name of prefix record | |
951 | yptrptr pointer to the pointer that points to where to hang the next | |
952 | dns_address structure | |
953 | bits number of bits we have already got | |
954 | bitvec the bits we have already got | |
955 | ||
956 | Returns: TRUE if any records were found | |
957 | */ | |
958 | ||
959 | static BOOL | |
960 | dns_find_prefix(dns_answer *dnsa, int which, uschar *name, dns_address | |
961 | ***yptrptr, int bits, uschar *bitvec) | |
962 | { | |
963 | BOOL yield = FALSE; | |
964 | dns_record *rr; | |
965 | dns_scan dnss; | |
966 | ||
967 | for (rr = dns_next_rr(dnsa, &dnss, which); | |
968 | rr != NULL; | |
969 | rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)) | |
970 | { | |
971 | uschar cbitvec[16]; | |
972 | if (rr->type != T_A6 || strcmpic(rr->name, name) != 0) continue; | |
973 | yield = TRUE; | |
974 | memcpy(cbitvec, bitvec, sizeof(cbitvec)); | |
975 | dns_complete_a6(yptrptr, dnsa, rr, bits, cbitvec); | |
976 | } | |
977 | ||
978 | return yield; | |
979 | } | |
980 | ||
981 | ||
982 | ||
983 | /************************************************* | |
984 | * Follow chains of A6 records * | |
985 | *************************************************/ | |
986 | ||
987 | /* A6 records may be incomplete, with pointers to other records containing more | |
988 | bits of the address. There can be a tree structure, leading to a number of | |
989 | addresses originating from a single initial A6 record. | |
990 | ||
991 | Arguments: | |
992 | yptrptr pointer to the pointer that points to where to hang the next | |
993 | dns_address structure | |
994 | dnsa the current DNS answer block | |
995 | rr the RR we have at present | |
996 | bits number of bits we have already got | |
997 | bitvec the bits we have already got | |
998 | ||
999 | Returns: nothing | |
1000 | */ | |
1001 | ||
1002 | static void | |
1003 | dns_complete_a6(dns_address ***yptrptr, dns_answer *dnsa, dns_record *rr, | |
1004 | int bits, uschar *bitvec) | |
1005 | { | |
1006 | static uschar bitmask[] = { 0xff, 0xfe, 0xfc, 0xf8, 0xf0, 0xe0, 0xc0, 0x80 }; | |
1007 | uschar *p = (uschar *)(rr->data); | |
1008 | int prefix_len, suffix_len; | |
1009 | int i, j, k; | |
1010 | uschar *chainptr; | |
1011 | uschar chain[264]; | |
1012 | dns_answer cdnsa; | |
1013 | ||
1014 | /* The prefix length is the first byte. It defines the prefix which is missing | |
1015 | from the data in this record as a number of bits. Zero means this is the end of | |
1016 | a chain. The suffix is the data in this record; only sufficient bytes to hold | |
1017 | it are supplied. There may be zero bytes. We have to ignore trailing bits that | |
1018 | we have already obtained from earlier RRs in the chain. */ | |
1019 | ||
1020 | prefix_len = *p++; /* bits */ | |
1021 | suffix_len = (128 - prefix_len + 7)/8; /* bytes */ | |
1022 | ||
1023 | /* If the prefix in this record is greater than the prefix in the previous | |
1024 | record in the chain, we have to ignore the record (RFC 2874). */ | |
1025 | ||
1026 | if (prefix_len > 128 - bits) return; | |
1027 | ||
1028 | /* In this little loop, the number of bits up to and including the current byte | |
1029 | is held in k. If we have none of the bits in this byte, we can just or it into | |
1030 | the current data. If we have all of the bits in this byte, we skip it. | |
1031 | Otherwise, some masking has to be done. */ | |
1032 | ||
1033 | for (i = suffix_len - 1, j = 15, k = 8; i >= 0; i--) | |
1034 | { | |
1035 | int required = k - bits; | |
1036 | if (required >= 8) bitvec[j] |= p[i]; | |
1037 | else if (required > 0) bitvec[j] |= p[i] & bitmask[required]; | |
1038 | j--; /* I tried putting these in the "for" statement, but gcc muttered */ | |
1039 | k += 8; /* about computed values not being used. */ | |
1040 | } | |
1041 | ||
1042 | /* If the prefix_length is zero, we are at the end of a chain. Build a | |
1043 | dns_address item with the current data, hang it onto the end of the chain, | |
1044 | adjust the hanging pointer, and we are done. */ | |
1045 | ||
1046 | if (prefix_len == 0) | |
1047 | { | |
1048 | dns_address *new = store_get(sizeof(dns_address) + 50); | |
1049 | inet_ntop(AF_INET6, bitvec, CS new->address, 50); | |
1050 | new->next = NULL; | |
1051 | **yptrptr = new; | |
1052 | *yptrptr = &(new->next); | |
1053 | return; | |
1054 | } | |
1055 | ||
1056 | /* Prefix length is not zero. Reset the number of bits that we have collected | |
1057 | so far, and extract the chain name. */ | |
1058 | ||
1059 | bits = 128 - prefix_len; | |
1060 | p += suffix_len; | |
1061 | ||
1062 | chainptr = chain; | |
1063 | while ((i = *p++) != 0) | |
1064 | { | |
1065 | if (chainptr != chain) *chainptr++ = '.'; | |
1066 | memcpy(chainptr, p, i); | |
1067 | chainptr += i; | |
1068 | p += i; | |
1069 | } | |
1070 | *chainptr = 0; | |
1071 | chainptr = chain; | |
1072 | ||
1073 | /* Now scan the current DNS response record to see if the additional section | |
1074 | contains the records we want. This processing can be cut out for testing | |
1075 | purposes. */ | |
1076 | ||
1077 | if (dns_find_prefix(dnsa, RESET_ADDITIONAL, chainptr, yptrptr, bits, bitvec)) | |
1078 | return; | |
1079 | ||
1080 | /* No chain records were found in the current DNS response block. Do a new DNS | |
1081 | lookup to try to find these records. This opens up the possibility of DNS | |
1082 | failures. We ignore them at this point; if all branches of the tree fail, there | |
1083 | will be no addresses at the end. */ | |
1084 | ||
1085 | if (dns_lookup(&cdnsa, chainptr, T_A6, NULL) == DNS_SUCCEED) | |
1086 | (void)dns_find_prefix(&cdnsa, RESET_ANSWERS, chainptr, yptrptr, bits, bitvec); | |
1087 | } | |
1088 | #endif /* HAVE_IPV6 && defined(SUPPORT_A6) */ | |
1089 | ||
1090 | ||
1091 | ||
1092 | ||
1093 | /************************************************* | |
1094 | * Get address(es) from DNS record * | |
1095 | *************************************************/ | |
1096 | ||
1097 | /* The record type is either T_A for an IPv4 address or T_AAAA (or T_A6 when | |
1098 | supported) for an IPv6 address. In the A6 case, there may be several addresses, | |
1099 | generated by following chains. A recursive function does all the hard work. A6 | |
1100 | records now look like passing into history, so the code is only included when | |
1101 | explicitly asked for. | |
1102 | ||
1103 | Argument: | |
1104 | dnsa the DNS answer block | |
1105 | rr the RR | |
1106 | ||
1107 | Returns: pointer a chain of dns_address items | |
1108 | */ | |
1109 | ||
1110 | dns_address * | |
1111 | dns_address_from_rr(dns_answer *dnsa, dns_record *rr) | |
1112 | { | |
1113 | dns_address *yield = NULL; | |
1114 | ||
1115 | #if HAVE_IPV6 && defined(SUPPORT_A6) | |
1116 | dns_address **yieldptr = &yield; | |
1117 | uschar bitvec[16]; | |
1118 | #else | |
1119 | dnsa = dnsa; /* Stop picky compilers warning */ | |
1120 | #endif | |
1121 | ||
1122 | if (rr->type == T_A) | |
1123 | { | |
1124 | uschar *p = (uschar *)(rr->data); | |
1125 | yield = store_get(sizeof(dns_address) + 20); | |
1126 | (void)sprintf(CS yield->address, "%d.%d.%d.%d", p[0], p[1], p[2], p[3]); | |
1127 | yield->next = NULL; | |
1128 | } | |
1129 | ||
1130 | #if HAVE_IPV6 | |
1131 | ||
1132 | #ifdef SUPPORT_A6 | |
1133 | else if (rr->type == T_A6) | |
1134 | { | |
1135 | memset(bitvec, 0, sizeof(bitvec)); | |
1136 | dns_complete_a6(&yieldptr, dnsa, rr, 0, bitvec); | |
1137 | } | |
1138 | #endif /* SUPPORT_A6 */ | |
1139 | ||
1140 | else | |
1141 | { | |
1142 | yield = store_get(sizeof(dns_address) + 50); | |
1143 | inet_ntop(AF_INET6, (uschar *)(rr->data), CS yield->address, 50); | |
1144 | yield->next = NULL; | |
1145 | } | |
1146 | #endif /* HAVE_IPV6 */ | |
1147 | ||
1148 | return yield; | |
1149 | } | |
1150 | ||
1151 | /* End of dns.c */ |