Commit | Line | Data |
---|---|---|
0756eb3c PH |
1 | /************************************************* |
2 | * Exim - an Internet mail transport agent * | |
3 | *************************************************/ | |
4 | ||
c4ceed07 | 5 | /* Copyright (c) University of Cambridge 1995 - 2012 */ |
0756eb3c PH |
6 | /* See the file NOTICE for conditions of use and distribution. */ |
7 | ||
8 | #include "../exim.h" | |
9 | #include "lf_functions.h" | |
0756eb3c PH |
10 | |
11 | ||
12 | ||
13 | /* Ancient systems (e.g. SunOS4) don't appear to have T_TXT defined in their | |
14 | header files. */ | |
15 | ||
16 | #ifndef T_TXT | |
17 | #define T_TXT 16 | |
18 | #endif | |
19 | ||
eae0036b PP |
20 | /* Many systems do not have T_SPF. */ |
21 | #ifndef T_SPF | |
22 | #define T_SPF 99 | |
23 | #endif | |
24 | ||
0756eb3c PH |
25 | /* Table of recognized DNS record types and their integer values. */ |
26 | ||
1ba28e2b | 27 | static const char *type_names[] = { |
0756eb3c PH |
28 | "a", |
29 | #if HAVE_IPV6 | |
30 | "aaaa", | |
31 | #ifdef SUPPORT_A6 | |
32 | "a6", | |
33 | #endif | |
34 | #endif | |
35 | "cname", | |
e5a9dba6 | 36 | "csa", |
0756eb3c | 37 | "mx", |
ea3bc19b | 38 | "mxh", |
0756eb3c PH |
39 | "ns", |
40 | "ptr", | |
eae0036b | 41 | "spf", |
0756eb3c | 42 | "srv", |
33397d19 | 43 | "txt", |
8e669ac1 | 44 | "zns" |
33397d19 | 45 | }; |
0756eb3c PH |
46 | |
47 | static int type_values[] = { | |
48 | T_A, | |
49 | #if HAVE_IPV6 | |
50 | T_AAAA, | |
51 | #ifdef SUPPORT_A6 | |
52 | T_A6, | |
53 | #endif | |
54 | #endif | |
55 | T_CNAME, | |
e5a9dba6 | 56 | T_CSA, /* Private type for "Client SMTP Authorization". */ |
0756eb3c | 57 | T_MX, |
ea3bc19b | 58 | T_MXH, /* Private type for "MX hostnames" */ |
0756eb3c PH |
59 | T_NS, |
60 | T_PTR, | |
eae0036b | 61 | T_SPF, |
0756eb3c | 62 | T_SRV, |
33397d19 PH |
63 | T_TXT, |
64 | T_ZNS /* Private type for "zone nameservers" */ | |
65 | }; | |
0756eb3c PH |
66 | |
67 | ||
68 | /************************************************* | |
69 | * Open entry point * | |
70 | *************************************************/ | |
71 | ||
72 | /* See local README for interface description. */ | |
73 | ||
e6d225ae | 74 | static void * |
0756eb3c PH |
75 | dnsdb_open(uschar *filename, uschar **errmsg) |
76 | { | |
77 | filename = filename; /* Keep picky compilers happy */ | |
78 | errmsg = errmsg; /* Ditto */ | |
79 | return (void *)(-1); /* Any non-0 value */ | |
80 | } | |
81 | ||
82 | ||
83 | ||
84 | /************************************************* | |
85 | * Find entry point for dnsdb * | |
86 | *************************************************/ | |
87 | ||
7bb56e1f PH |
88 | /* See local README for interface description. The query in the "keystring" may |
89 | consist of a number of parts. | |
90 | ||
8e669ac1 PH |
91 | (a) If the first significant character is '>' then the next character is the |
92 | separator character that is used when multiple records are found. The default | |
7bb56e1f PH |
93 | separator is newline. |
94 | ||
0d0c6357 NM |
95 | (b) If the next character is ',' then the next character is the separator |
96 | character used for multiple items of text in "TXT" records. Alternatively, | |
97 | if the next character is ';' then these multiple items are concatenated with | |
98 | no separator. With neither of these options specified, only the first item | |
99 | is output. | |
100 | ||
101 | (c) If the next sequence of characters is 'defer_FOO' followed by a comma, | |
ff4dbb19 PH |
102 | the defer behaviour is set to FOO. The possible behaviours are: 'strict', where |
103 | any defer causes the whole lookup to defer; 'lax', where a defer causes the | |
104 | whole lookup to defer only if none of the DNS queries succeeds; and 'never', | |
105 | where all defers are as if the lookup failed. The default is 'lax'. | |
106 | ||
0d0c6357 | 107 | (d) If the next sequence of characters is a sequence of letters and digits |
8e669ac1 | 108 | followed by '=', it is interpreted as the name of the DNS record type. The |
ff4dbb19 | 109 | default is "TXT". |
7bb56e1f | 110 | |
0d0c6357 | 111 | (e) Then there follows list of domain names. This is a generalized Exim list, |
8e669ac1 | 112 | which may start with '<' in order to set a specific separator. The default |
7bb56e1f | 113 | separator, as always, is colon. */ |
0756eb3c | 114 | |
e6d225ae | 115 | static int |
0756eb3c PH |
116 | dnsdb_find(void *handle, uschar *filename, uschar *keystring, int length, |
117 | uschar **result, uschar **errmsg, BOOL *do_cache) | |
118 | { | |
119 | int rc; | |
120 | int size = 256; | |
121 | int ptr = 0; | |
7bb56e1f | 122 | int sep = 0; |
ff4dbb19 | 123 | int defer_mode = PASS; |
0756eb3c | 124 | int type = T_TXT; |
c38d6da9 | 125 | int failrc = FAIL; |
7bb56e1f | 126 | uschar *outsep = US"\n"; |
0d0c6357 | 127 | uschar *outsep2 = NULL; |
e5a9dba6 | 128 | uschar *equals, *domain, *found; |
0756eb3c PH |
129 | uschar buffer[256]; |
130 | ||
131 | /* Because we're the working in the search pool, we try to reclaim as much | |
132 | store as possible later, so we preallocate the result here */ | |
133 | ||
134 | uschar *yield = store_get(size); | |
135 | ||
136 | dns_record *rr; | |
137 | dns_answer dnsa; | |
138 | dns_scan dnss; | |
139 | ||
140 | handle = handle; /* Keep picky compilers happy */ | |
141 | filename = filename; | |
142 | length = length; | |
143 | do_cache = do_cache; | |
144 | ||
0d0c6357 NM |
145 | /* If the string starts with '>' we change the output separator. |
146 | If it's followed by ';' or ',' we set the TXT output separator. */ | |
0756eb3c | 147 | |
7bb56e1f PH |
148 | while (isspace(*keystring)) keystring++; |
149 | if (*keystring == '>') | |
0756eb3c | 150 | { |
7bb56e1f | 151 | outsep = keystring + 1; |
8e669ac1 | 152 | keystring += 2; |
0d0c6357 NM |
153 | if (*keystring == ',') |
154 | { | |
155 | outsep2 = keystring + 1; | |
156 | keystring += 2; | |
157 | } | |
158 | else if (*keystring == ';') | |
159 | { | |
160 | outsep2 = US""; | |
161 | keystring++; | |
162 | } | |
7bb56e1f | 163 | while (isspace(*keystring)) keystring++; |
8e669ac1 | 164 | } |
7bb56e1f | 165 | |
ff4dbb19 PH |
166 | /* Check for a defer behaviour keyword. */ |
167 | ||
168 | if (strncmpic(keystring, US"defer_", 6) == 0) | |
169 | { | |
170 | keystring += 6; | |
171 | if (strncmpic(keystring, US"strict", 6) == 0) | |
172 | { | |
173 | defer_mode = DEFER; | |
174 | keystring += 6; | |
175 | } | |
176 | else if (strncmpic(keystring, US"lax", 3) == 0) | |
177 | { | |
178 | defer_mode = PASS; | |
179 | keystring += 3; | |
180 | } | |
181 | else if (strncmpic(keystring, US"never", 5) == 0) | |
182 | { | |
183 | defer_mode = OK; | |
184 | keystring += 5; | |
185 | } | |
186 | else | |
187 | { | |
188 | *errmsg = US"unsupported dnsdb defer behaviour"; | |
189 | return DEFER; | |
190 | } | |
191 | while (isspace(*keystring)) keystring++; | |
192 | if (*keystring++ != ',') | |
193 | { | |
194 | *errmsg = US"dnsdb defer behaviour syntax error"; | |
195 | return DEFER; | |
196 | } | |
197 | while (isspace(*keystring)) keystring++; | |
198 | } | |
199 | ||
7bb56e1f PH |
200 | /* If the keystring contains an = this must be preceded by a valid type name. */ |
201 | ||
202 | if ((equals = Ustrchr(keystring, '=')) != NULL) | |
203 | { | |
204 | int i, len; | |
205 | uschar *tend = equals; | |
8e669ac1 PH |
206 | |
207 | while (tend > keystring && isspace(tend[-1])) tend--; | |
208 | len = tend - keystring; | |
209 | ||
0756eb3c PH |
210 | for (i = 0; i < sizeof(type_names)/sizeof(uschar *); i++) |
211 | { | |
212 | if (len == Ustrlen(type_names[i]) && | |
213 | strncmpic(keystring, US type_names[i], len) == 0) | |
214 | { | |
215 | type = type_values[i]; | |
216 | break; | |
217 | } | |
218 | } | |
8e669ac1 | 219 | |
0756eb3c PH |
220 | if (i >= sizeof(type_names)/sizeof(uschar *)) |
221 | { | |
222 | *errmsg = US"unsupported DNS record type"; | |
223 | return DEFER; | |
224 | } | |
8e669ac1 | 225 | |
7bb56e1f PH |
226 | keystring = equals + 1; |
227 | while (isspace(*keystring)) keystring++; | |
0756eb3c | 228 | } |
8e669ac1 | 229 | |
7bb56e1f | 230 | /* Initialize the resolver in case this is the first time it has been used. */ |
0756eb3c PH |
231 | |
232 | dns_init(FALSE, FALSE); | |
0756eb3c | 233 | |
8e669ac1 PH |
234 | /* The remainder of the string must be a list of domains. As long as the lookup |
235 | for at least one of them succeeds, we return success. Failure means that none | |
236 | of them were found. | |
0756eb3c | 237 | |
8e669ac1 PH |
238 | The original implementation did not support a list of domains. Adding the list |
239 | feature is compatible, except in one case: when PTR records are being looked up | |
240 | for a single IPv6 address. Fortunately, we can hack in a compatibility feature | |
241 | here: If the type is PTR and no list separator is specified, and the entire | |
242 | remaining string is valid as an IP address, set an impossible separator so that | |
7bb56e1f | 243 | it is treated as one item. */ |
33397d19 | 244 | |
7bb56e1f | 245 | if (type == T_PTR && keystring[0] != '<' && |
7e66e54d | 246 | string_is_ip_address(keystring, NULL) != 0) |
7bb56e1f | 247 | sep = -1; |
0756eb3c | 248 | |
7bb56e1f | 249 | /* Now scan the list and do a lookup for each item */ |
0756eb3c | 250 | |
8e669ac1 | 251 | while ((domain = string_nextinlist(&keystring, &sep, buffer, sizeof(buffer))) |
7bb56e1f | 252 | != NULL) |
8e669ac1 | 253 | { |
7bb56e1f | 254 | uschar rbuffer[256]; |
e5a9dba6 PH |
255 | int searchtype = (type == T_CSA)? T_SRV : /* record type we want */ |
256 | (type == T_MXH)? T_MX : | |
257 | (type == T_ZNS)? T_NS : type; | |
258 | ||
259 | /* If the type is PTR or CSA, we have to construct the relevant magic lookup | |
260 | key if the original is an IP address (some experimental protocols are using | |
261 | PTR records for different purposes where the key string is a host name, and | |
262 | Exim's extended CSA can be keyed by domains or IP addresses). This code for | |
263 | doing the reversal is now in a separate function. */ | |
264 | ||
265 | if ((type == T_PTR || type == T_CSA) && | |
7e66e54d | 266 | string_is_ip_address(domain, NULL) != 0) |
0756eb3c | 267 | { |
7bb56e1f PH |
268 | dns_build_reverse(domain, rbuffer); |
269 | domain = rbuffer; | |
0756eb3c | 270 | } |
8e669ac1 | 271 | |
7bb56e1f | 272 | DEBUG(D_lookup) debug_printf("dnsdb key: %s\n", domain); |
8e669ac1 | 273 | |
28e6ef29 TF |
274 | /* Do the lookup and sort out the result. There are three special types that |
275 | are handled specially: T_CSA, T_ZNS and T_MXH. The former two are handled in | |
276 | a special lookup function so that the facility could be used from other | |
277 | parts of the Exim code. The latter affects only what happens later on in | |
278 | this function, but for tidiness it is handled in a similar way. If the | |
279 | lookup fails, continue with the next domain. In the case of DEFER, adjust | |
280 | the final "nothing found" result, but carry on to the next domain. */ | |
8e669ac1 | 281 | |
e5a9dba6 PH |
282 | found = domain; |
283 | rc = dns_special_lookup(&dnsa, domain, type, &found); | |
8e669ac1 | 284 | |
7bb56e1f | 285 | if (rc == DNS_NOMATCH || rc == DNS_NODATA) continue; |
c38d6da9 PH |
286 | if (rc != DNS_SUCCEED) |
287 | { | |
ff4dbb19 PH |
288 | if (defer_mode == DEFER) return DEFER; /* always defer */ |
289 | else if (defer_mode == PASS) failrc = DEFER; /* defer only if all do */ | |
290 | continue; /* treat defer as fail */ | |
c38d6da9 | 291 | } |
8e669ac1 | 292 | |
ea3bc19b PH |
293 | /* Search the returned records */ |
294 | ||
7bb56e1f PH |
295 | for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS); |
296 | rr != NULL; | |
297 | rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT)) | |
0756eb3c | 298 | { |
ea3bc19b | 299 | if (rr->type != searchtype) continue; |
8e669ac1 PH |
300 | |
301 | /* There may be several addresses from an A6 record. Put the configured | |
302 | separator between them, just as for between several records. However, A6 | |
7bb56e1f | 303 | support is not normally configured these days. */ |
8e669ac1 | 304 | |
7bb56e1f PH |
305 | if (type == T_A || |
306 | #ifdef SUPPORT_A6 | |
307 | type == T_A6 || | |
308 | #endif | |
309 | type == T_AAAA) | |
0756eb3c | 310 | { |
7bb56e1f PH |
311 | dns_address *da; |
312 | for (da = dns_address_from_rr(&dnsa, rr); da != NULL; da = da->next) | |
313 | { | |
314 | if (ptr != 0) yield = string_cat(yield, &size, &ptr, outsep, 1); | |
8e669ac1 | 315 | yield = string_cat(yield, &size, &ptr, da->address, |
7bb56e1f PH |
316 | Ustrlen(da->address)); |
317 | } | |
318 | continue; | |
0756eb3c | 319 | } |
8e669ac1 PH |
320 | |
321 | /* Other kinds of record just have one piece of data each, but there may be | |
7bb56e1f | 322 | several of them, of course. */ |
8e669ac1 | 323 | |
7bb56e1f | 324 | if (ptr != 0) yield = string_cat(yield, &size, &ptr, outsep, 1); |
8e669ac1 | 325 | |
eae0036b | 326 | if (type == T_TXT || type == T_SPF) |
0756eb3c | 327 | { |
0d0c6357 NM |
328 | if (outsep2 == NULL) |
329 | { | |
330 | /* output only the first item of data */ | |
331 | yield = string_cat(yield, &size, &ptr, (uschar *)(rr->data+1), | |
332 | (rr->data)[0]); | |
333 | } | |
334 | else | |
80a47a2c | 335 | { |
0d0c6357 NM |
336 | /* output all items */ |
337 | int data_offset = 0; | |
338 | while (data_offset < rr->size) | |
339 | { | |
340 | uschar chunk_len = (rr->data)[data_offset++]; | |
341 | if (outsep2[0] != '\0' && data_offset != 1) | |
342 | yield = string_cat(yield, &size, &ptr, outsep2, 1); | |
343 | yield = string_cat(yield, &size, &ptr, | |
344 | (uschar *)((rr->data)+data_offset), chunk_len); | |
345 | data_offset += chunk_len; | |
346 | } | |
80a47a2c | 347 | } |
0756eb3c | 348 | } |
e5a9dba6 | 349 | else /* T_CNAME, T_CSA, T_MX, T_MXH, T_NS, T_PTR, T_SRV */ |
0756eb3c | 350 | { |
e5a9dba6 | 351 | int priority, weight, port; |
7bb56e1f PH |
352 | uschar s[264]; |
353 | uschar *p = (uschar *)(rr->data); | |
8e669ac1 | 354 | |
ea3bc19b PH |
355 | if (type == T_MXH) |
356 | { | |
357 | /* mxh ignores the priority number and includes only the hostnames */ | |
e5a9dba6 | 358 | GETSHORT(priority, p); |
ea3bc19b PH |
359 | } |
360 | else if (type == T_MX) | |
7bb56e1f | 361 | { |
e5a9dba6 PH |
362 | GETSHORT(priority, p); |
363 | sprintf(CS s, "%d ", priority); | |
7bb56e1f PH |
364 | yield = string_cat(yield, &size, &ptr, s, Ustrlen(s)); |
365 | } | |
366 | else if (type == T_SRV) | |
367 | { | |
e5a9dba6 | 368 | GETSHORT(priority, p); |
7bb56e1f PH |
369 | GETSHORT(weight, p); |
370 | GETSHORT(port, p); | |
e5a9dba6 | 371 | sprintf(CS s, "%d %d %d ", priority, weight, port); |
7bb56e1f PH |
372 | yield = string_cat(yield, &size, &ptr, s, Ustrlen(s)); |
373 | } | |
e5a9dba6 PH |
374 | else if (type == T_CSA) |
375 | { | |
376 | /* See acl_verify_csa() for more comments about CSA. */ | |
377 | ||
378 | GETSHORT(priority, p); | |
379 | GETSHORT(weight, p); | |
380 | GETSHORT(port, p); | |
381 | ||
382 | if (priority != 1) continue; /* CSA version must be 1 */ | |
383 | ||
384 | /* If the CSA record we found is not the one we asked for, analyse | |
385 | the subdomain assertions in the port field, else analyse the direct | |
386 | authorization status in the weight field. */ | |
387 | ||
388 | if (found != domain) | |
389 | { | |
390 | if (port & 1) *s = 'X'; /* explicit authorization required */ | |
391 | else *s = '?'; /* no subdomain assertions here */ | |
392 | } | |
393 | else | |
394 | { | |
395 | if (weight < 2) *s = 'N'; /* not authorized */ | |
396 | else if (weight == 2) *s = 'Y'; /* authorized */ | |
397 | else if (weight == 3) *s = '?'; /* unauthorizable */ | |
398 | else continue; /* invalid */ | |
399 | } | |
400 | ||
401 | s[1] = ' '; | |
402 | yield = string_cat(yield, &size, &ptr, s, 2); | |
403 | } | |
404 | ||
405 | /* GETSHORT() has advanced the pointer to the target domain. */ | |
8e669ac1 | 406 | |
7bb56e1f PH |
407 | rc = dn_expand(dnsa.answer, dnsa.answer + dnsa.answerlen, p, |
408 | (DN_EXPAND_ARG4_TYPE)(s), sizeof(s)); | |
8e669ac1 | 409 | |
7bb56e1f PH |
410 | /* If an overlong response was received, the data will have been |
411 | truncated and dn_expand may fail. */ | |
8e669ac1 | 412 | |
7bb56e1f PH |
413 | if (rc < 0) |
414 | { | |
415 | log_write(0, LOG_MAIN, "host name alias list truncated: type=%s " | |
416 | "domain=%s", dns_text_type(type), domain); | |
417 | break; | |
418 | } | |
419 | else yield = string_cat(yield, &size, &ptr, s, Ustrlen(s)); | |
0756eb3c | 420 | } |
7bb56e1f PH |
421 | } /* Loop for list of returned records */ |
422 | } /* Loop for list of domains */ | |
423 | ||
424 | /* Reclaim unused memory */ | |
0756eb3c | 425 | |
7bb56e1f PH |
426 | store_reset(yield + ptr + 1); |
427 | ||
8e669ac1 | 428 | /* If ptr == 0 we have not found anything. Otherwise, insert the terminating |
7bb56e1f PH |
429 | zero and return the result. */ |
430 | ||
c38d6da9 | 431 | if (ptr == 0) return failrc; |
0756eb3c | 432 | yield[ptr] = 0; |
0756eb3c | 433 | *result = yield; |
0756eb3c PH |
434 | return OK; |
435 | } | |
436 | ||
6545de78 PP |
437 | |
438 | ||
439 | /************************************************* | |
440 | * Version reporting entry point * | |
441 | *************************************************/ | |
442 | ||
443 | /* See local README for interface description. */ | |
444 | ||
445 | #include "../version.h" | |
446 | ||
447 | void | |
448 | dnsdb_version_report(FILE *f) | |
449 | { | |
450 | #ifdef DYNLOOKUP | |
451 | fprintf(f, "Library version: DNSDB: Exim version %s\n", EXIM_VERSION_STR); | |
452 | #endif | |
453 | } | |
454 | ||
455 | ||
e6d225ae DW |
456 | static lookup_info _lookup_info = { |
457 | US"dnsdb", /* lookup name */ | |
458 | lookup_querystyle, /* query style */ | |
459 | dnsdb_open, /* open function */ | |
460 | NULL, /* check function */ | |
461 | dnsdb_find, /* find function */ | |
462 | NULL, /* no close function */ | |
463 | NULL, /* no tidy function */ | |
6545de78 PP |
464 | NULL, /* no quoting function */ |
465 | dnsdb_version_report /* version reporting */ | |
e6d225ae DW |
466 | }; |
467 | ||
468 | #ifdef DYNLOOKUP | |
469 | #define dnsdb_lookup_module_info _lookup_module_info | |
470 | #endif | |
471 | ||
472 | static lookup_info *_lookup_list[] = { &_lookup_info }; | |
473 | lookup_module_info dnsdb_lookup_module_info = { LOOKUP_MODULE_INFO_MAGIC, _lookup_list, 1 }; | |
474 | ||
0756eb3c | 475 | /* End of lookups/dnsdb.c */ |