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0d0c6357 | 1 | /* $Cambridge: exim/src/src/lookups/dnsdb.c,v 1.20 2010/05/29 19:23:26 nm4 Exp $ */ |
0756eb3c PH |
2 | |
3 | /************************************************* | |
4 | * Exim - an Internet mail transport agent * | |
5 | *************************************************/ | |
6 | ||
0a49a7a4 | 7 | /* Copyright (c) University of Cambridge 1995 - 2009 */ |
0756eb3c PH |
8 | /* See the file NOTICE for conditions of use and distribution. */ |
9 | ||
10 | #include "../exim.h" | |
11 | #include "lf_functions.h" | |
0756eb3c PH |
12 | |
13 | ||
14 | ||
15 | /* Ancient systems (e.g. SunOS4) don't appear to have T_TXT defined in their | |
16 | header files. */ | |
17 | ||
18 | #ifndef T_TXT | |
19 | #define T_TXT 16 | |
20 | #endif | |
21 | ||
22 | /* Table of recognized DNS record types and their integer values. */ | |
23 | ||
1ba28e2b | 24 | static const char *type_names[] = { |
0756eb3c PH |
25 | "a", |
26 | #if HAVE_IPV6 | |
27 | "aaaa", | |
28 | #ifdef SUPPORT_A6 | |
29 | "a6", | |
30 | #endif | |
31 | #endif | |
32 | "cname", | |
e5a9dba6 | 33 | "csa", |
0756eb3c | 34 | "mx", |
ea3bc19b | 35 | "mxh", |
0756eb3c PH |
36 | "ns", |
37 | "ptr", | |
38 | "srv", | |
33397d19 | 39 | "txt", |
8e669ac1 | 40 | "zns" |
33397d19 | 41 | }; |
0756eb3c PH |
42 | |
43 | static int type_values[] = { | |
44 | T_A, | |
45 | #if HAVE_IPV6 | |
46 | T_AAAA, | |
47 | #ifdef SUPPORT_A6 | |
48 | T_A6, | |
49 | #endif | |
50 | #endif | |
51 | T_CNAME, | |
e5a9dba6 | 52 | T_CSA, /* Private type for "Client SMTP Authorization". */ |
0756eb3c | 53 | T_MX, |
ea3bc19b | 54 | T_MXH, /* Private type for "MX hostnames" */ |
0756eb3c PH |
55 | T_NS, |
56 | T_PTR, | |
57 | T_SRV, | |
33397d19 PH |
58 | T_TXT, |
59 | T_ZNS /* Private type for "zone nameservers" */ | |
60 | }; | |
0756eb3c PH |
61 | |
62 | ||
63 | /************************************************* | |
64 | * Open entry point * | |
65 | *************************************************/ | |
66 | ||
67 | /* See local README for interface description. */ | |
68 | ||
e6d225ae | 69 | static void * |
0756eb3c PH |
70 | dnsdb_open(uschar *filename, uschar **errmsg) |
71 | { | |
72 | filename = filename; /* Keep picky compilers happy */ | |
73 | errmsg = errmsg; /* Ditto */ | |
74 | return (void *)(-1); /* Any non-0 value */ | |
75 | } | |
76 | ||
77 | ||
78 | ||
79 | /************************************************* | |
80 | * Find entry point for dnsdb * | |
81 | *************************************************/ | |
82 | ||
7bb56e1f PH |
83 | /* See local README for interface description. The query in the "keystring" may |
84 | consist of a number of parts. | |
85 | ||
8e669ac1 PH |
86 | (a) If the first significant character is '>' then the next character is the |
87 | separator character that is used when multiple records are found. The default | |
7bb56e1f PH |
88 | separator is newline. |
89 | ||
0d0c6357 NM |
90 | (b) If the next character is ',' then the next character is the separator |
91 | character used for multiple items of text in "TXT" records. Alternatively, | |
92 | if the next character is ';' then these multiple items are concatenated with | |
93 | no separator. With neither of these options specified, only the first item | |
94 | is output. | |
95 | ||
96 | (c) If the next sequence of characters is 'defer_FOO' followed by a comma, | |
ff4dbb19 PH |
97 | the defer behaviour is set to FOO. The possible behaviours are: 'strict', where |
98 | any defer causes the whole lookup to defer; 'lax', where a defer causes the | |
99 | whole lookup to defer only if none of the DNS queries succeeds; and 'never', | |
100 | where all defers are as if the lookup failed. The default is 'lax'. | |
101 | ||
0d0c6357 | 102 | (d) If the next sequence of characters is a sequence of letters and digits |
8e669ac1 | 103 | followed by '=', it is interpreted as the name of the DNS record type. The |
ff4dbb19 | 104 | default is "TXT". |
7bb56e1f | 105 | |
0d0c6357 | 106 | (e) Then there follows list of domain names. This is a generalized Exim list, |
8e669ac1 | 107 | which may start with '<' in order to set a specific separator. The default |
7bb56e1f | 108 | separator, as always, is colon. */ |
0756eb3c | 109 | |
e6d225ae | 110 | static int |
0756eb3c PH |
111 | dnsdb_find(void *handle, uschar *filename, uschar *keystring, int length, |
112 | uschar **result, uschar **errmsg, BOOL *do_cache) | |
113 | { | |
114 | int rc; | |
115 | int size = 256; | |
116 | int ptr = 0; | |
7bb56e1f | 117 | int sep = 0; |
ff4dbb19 | 118 | int defer_mode = PASS; |
0756eb3c | 119 | int type = T_TXT; |
c38d6da9 | 120 | int failrc = FAIL; |
7bb56e1f | 121 | uschar *outsep = US"\n"; |
0d0c6357 | 122 | uschar *outsep2 = NULL; |
e5a9dba6 | 123 | uschar *equals, *domain, *found; |
0756eb3c PH |
124 | uschar buffer[256]; |
125 | ||
126 | /* Because we're the working in the search pool, we try to reclaim as much | |
127 | store as possible later, so we preallocate the result here */ | |
128 | ||
129 | uschar *yield = store_get(size); | |
130 | ||
131 | dns_record *rr; | |
132 | dns_answer dnsa; | |
133 | dns_scan dnss; | |
134 | ||
135 | handle = handle; /* Keep picky compilers happy */ | |
136 | filename = filename; | |
137 | length = length; | |
138 | do_cache = do_cache; | |
139 | ||
0d0c6357 NM |
140 | /* If the string starts with '>' we change the output separator. |
141 | If it's followed by ';' or ',' we set the TXT output separator. */ | |
0756eb3c | 142 | |
7bb56e1f PH |
143 | while (isspace(*keystring)) keystring++; |
144 | if (*keystring == '>') | |
0756eb3c | 145 | { |
7bb56e1f | 146 | outsep = keystring + 1; |
8e669ac1 | 147 | keystring += 2; |
0d0c6357 NM |
148 | if (*keystring == ',') |
149 | { | |
150 | outsep2 = keystring + 1; | |
151 | keystring += 2; | |
152 | } | |
153 | else if (*keystring == ';') | |
154 | { | |
155 | outsep2 = US""; | |
156 | keystring++; | |
157 | } | |
7bb56e1f | 158 | while (isspace(*keystring)) keystring++; |
8e669ac1 | 159 | } |
7bb56e1f | 160 | |
ff4dbb19 PH |
161 | /* Check for a defer behaviour keyword. */ |
162 | ||
163 | if (strncmpic(keystring, US"defer_", 6) == 0) | |
164 | { | |
165 | keystring += 6; | |
166 | if (strncmpic(keystring, US"strict", 6) == 0) | |
167 | { | |
168 | defer_mode = DEFER; | |
169 | keystring += 6; | |
170 | } | |
171 | else if (strncmpic(keystring, US"lax", 3) == 0) | |
172 | { | |
173 | defer_mode = PASS; | |
174 | keystring += 3; | |
175 | } | |
176 | else if (strncmpic(keystring, US"never", 5) == 0) | |
177 | { | |
178 | defer_mode = OK; | |
179 | keystring += 5; | |
180 | } | |
181 | else | |
182 | { | |
183 | *errmsg = US"unsupported dnsdb defer behaviour"; | |
184 | return DEFER; | |
185 | } | |
186 | while (isspace(*keystring)) keystring++; | |
187 | if (*keystring++ != ',') | |
188 | { | |
189 | *errmsg = US"dnsdb defer behaviour syntax error"; | |
190 | return DEFER; | |
191 | } | |
192 | while (isspace(*keystring)) keystring++; | |
193 | } | |
194 | ||
7bb56e1f PH |
195 | /* If the keystring contains an = this must be preceded by a valid type name. */ |
196 | ||
197 | if ((equals = Ustrchr(keystring, '=')) != NULL) | |
198 | { | |
199 | int i, len; | |
200 | uschar *tend = equals; | |
8e669ac1 PH |
201 | |
202 | while (tend > keystring && isspace(tend[-1])) tend--; | |
203 | len = tend - keystring; | |
204 | ||
0756eb3c PH |
205 | for (i = 0; i < sizeof(type_names)/sizeof(uschar *); i++) |
206 | { | |
207 | if (len == Ustrlen(type_names[i]) && | |
208 | strncmpic(keystring, US type_names[i], len) == 0) | |
209 | { | |
210 | type = type_values[i]; | |
211 | break; | |
212 | } | |
213 | } | |
8e669ac1 | 214 | |
0756eb3c PH |
215 | if (i >= sizeof(type_names)/sizeof(uschar *)) |
216 | { | |
217 | *errmsg = US"unsupported DNS record type"; | |
218 | return DEFER; | |
219 | } | |
8e669ac1 | 220 | |
7bb56e1f PH |
221 | keystring = equals + 1; |
222 | while (isspace(*keystring)) keystring++; | |
0756eb3c | 223 | } |
8e669ac1 | 224 | |
7bb56e1f | 225 | /* Initialize the resolver in case this is the first time it has been used. */ |
0756eb3c PH |
226 | |
227 | dns_init(FALSE, FALSE); | |
0756eb3c | 228 | |
8e669ac1 PH |
229 | /* The remainder of the string must be a list of domains. As long as the lookup |
230 | for at least one of them succeeds, we return success. Failure means that none | |
231 | of them were found. | |
0756eb3c | 232 | |
8e669ac1 PH |
233 | The original implementation did not support a list of domains. Adding the list |
234 | feature is compatible, except in one case: when PTR records are being looked up | |
235 | for a single IPv6 address. Fortunately, we can hack in a compatibility feature | |
236 | here: If the type is PTR and no list separator is specified, and the entire | |
237 | remaining string is valid as an IP address, set an impossible separator so that | |
7bb56e1f | 238 | it is treated as one item. */ |
33397d19 | 239 | |
7bb56e1f | 240 | if (type == T_PTR && keystring[0] != '<' && |
7e66e54d | 241 | string_is_ip_address(keystring, NULL) != 0) |
7bb56e1f | 242 | sep = -1; |
0756eb3c | 243 | |
7bb56e1f | 244 | /* Now scan the list and do a lookup for each item */ |
0756eb3c | 245 | |
8e669ac1 | 246 | while ((domain = string_nextinlist(&keystring, &sep, buffer, sizeof(buffer))) |
7bb56e1f | 247 | != NULL) |
8e669ac1 | 248 | { |
7bb56e1f | 249 | uschar rbuffer[256]; |
e5a9dba6 PH |
250 | int searchtype = (type == T_CSA)? T_SRV : /* record type we want */ |
251 | (type == T_MXH)? T_MX : | |
252 | (type == T_ZNS)? T_NS : type; | |
253 | ||
254 | /* If the type is PTR or CSA, we have to construct the relevant magic lookup | |
255 | key if the original is an IP address (some experimental protocols are using | |
256 | PTR records for different purposes where the key string is a host name, and | |
257 | Exim's extended CSA can be keyed by domains or IP addresses). This code for | |
258 | doing the reversal is now in a separate function. */ | |
259 | ||
260 | if ((type == T_PTR || type == T_CSA) && | |
7e66e54d | 261 | string_is_ip_address(domain, NULL) != 0) |
0756eb3c | 262 | { |
7bb56e1f PH |
263 | dns_build_reverse(domain, rbuffer); |
264 | domain = rbuffer; | |
0756eb3c | 265 | } |
8e669ac1 | 266 | |
7bb56e1f | 267 | DEBUG(D_lookup) debug_printf("dnsdb key: %s\n", domain); |
8e669ac1 | 268 | |
28e6ef29 TF |
269 | /* Do the lookup and sort out the result. There are three special types that |
270 | are handled specially: T_CSA, T_ZNS and T_MXH. The former two are handled in | |
271 | a special lookup function so that the facility could be used from other | |
272 | parts of the Exim code. The latter affects only what happens later on in | |
273 | this function, but for tidiness it is handled in a similar way. If the | |
274 | lookup fails, continue with the next domain. In the case of DEFER, adjust | |
275 | the final "nothing found" result, but carry on to the next domain. */ | |
8e669ac1 | 276 | |
e5a9dba6 PH |
277 | found = domain; |
278 | rc = dns_special_lookup(&dnsa, domain, type, &found); | |
8e669ac1 | 279 | |
7bb56e1f | 280 | if (rc == DNS_NOMATCH || rc == DNS_NODATA) continue; |
c38d6da9 PH |
281 | if (rc != DNS_SUCCEED) |
282 | { | |
ff4dbb19 PH |
283 | if (defer_mode == DEFER) return DEFER; /* always defer */ |
284 | else if (defer_mode == PASS) failrc = DEFER; /* defer only if all do */ | |
285 | continue; /* treat defer as fail */ | |
c38d6da9 | 286 | } |
8e669ac1 | 287 | |
ea3bc19b PH |
288 | /* Search the returned records */ |
289 | ||
7bb56e1f PH |
290 | for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS); |
291 | rr != NULL; | |
292 | rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT)) | |
0756eb3c | 293 | { |
ea3bc19b | 294 | if (rr->type != searchtype) continue; |
8e669ac1 PH |
295 | |
296 | /* There may be several addresses from an A6 record. Put the configured | |
297 | separator between them, just as for between several records. However, A6 | |
7bb56e1f | 298 | support is not normally configured these days. */ |
8e669ac1 | 299 | |
7bb56e1f PH |
300 | if (type == T_A || |
301 | #ifdef SUPPORT_A6 | |
302 | type == T_A6 || | |
303 | #endif | |
304 | type == T_AAAA) | |
0756eb3c | 305 | { |
7bb56e1f PH |
306 | dns_address *da; |
307 | for (da = dns_address_from_rr(&dnsa, rr); da != NULL; da = da->next) | |
308 | { | |
309 | if (ptr != 0) yield = string_cat(yield, &size, &ptr, outsep, 1); | |
8e669ac1 | 310 | yield = string_cat(yield, &size, &ptr, da->address, |
7bb56e1f PH |
311 | Ustrlen(da->address)); |
312 | } | |
313 | continue; | |
0756eb3c | 314 | } |
8e669ac1 PH |
315 | |
316 | /* Other kinds of record just have one piece of data each, but there may be | |
7bb56e1f | 317 | several of them, of course. */ |
8e669ac1 | 318 | |
7bb56e1f | 319 | if (ptr != 0) yield = string_cat(yield, &size, &ptr, outsep, 1); |
8e669ac1 | 320 | |
7bb56e1f | 321 | if (type == T_TXT) |
0756eb3c | 322 | { |
0d0c6357 NM |
323 | if (outsep2 == NULL) |
324 | { | |
325 | /* output only the first item of data */ | |
326 | yield = string_cat(yield, &size, &ptr, (uschar *)(rr->data+1), | |
327 | (rr->data)[0]); | |
328 | } | |
329 | else | |
80a47a2c | 330 | { |
0d0c6357 NM |
331 | /* output all items */ |
332 | int data_offset = 0; | |
333 | while (data_offset < rr->size) | |
334 | { | |
335 | uschar chunk_len = (rr->data)[data_offset++]; | |
336 | if (outsep2[0] != '\0' && data_offset != 1) | |
337 | yield = string_cat(yield, &size, &ptr, outsep2, 1); | |
338 | yield = string_cat(yield, &size, &ptr, | |
339 | (uschar *)((rr->data)+data_offset), chunk_len); | |
340 | data_offset += chunk_len; | |
341 | } | |
80a47a2c | 342 | } |
0756eb3c | 343 | } |
e5a9dba6 | 344 | else /* T_CNAME, T_CSA, T_MX, T_MXH, T_NS, T_PTR, T_SRV */ |
0756eb3c | 345 | { |
e5a9dba6 | 346 | int priority, weight, port; |
7bb56e1f PH |
347 | uschar s[264]; |
348 | uschar *p = (uschar *)(rr->data); | |
8e669ac1 | 349 | |
ea3bc19b PH |
350 | if (type == T_MXH) |
351 | { | |
352 | /* mxh ignores the priority number and includes only the hostnames */ | |
e5a9dba6 | 353 | GETSHORT(priority, p); |
ea3bc19b PH |
354 | } |
355 | else if (type == T_MX) | |
7bb56e1f | 356 | { |
e5a9dba6 PH |
357 | GETSHORT(priority, p); |
358 | sprintf(CS s, "%d ", priority); | |
7bb56e1f PH |
359 | yield = string_cat(yield, &size, &ptr, s, Ustrlen(s)); |
360 | } | |
361 | else if (type == T_SRV) | |
362 | { | |
e5a9dba6 | 363 | GETSHORT(priority, p); |
7bb56e1f PH |
364 | GETSHORT(weight, p); |
365 | GETSHORT(port, p); | |
e5a9dba6 | 366 | sprintf(CS s, "%d %d %d ", priority, weight, port); |
7bb56e1f PH |
367 | yield = string_cat(yield, &size, &ptr, s, Ustrlen(s)); |
368 | } | |
e5a9dba6 PH |
369 | else if (type == T_CSA) |
370 | { | |
371 | /* See acl_verify_csa() for more comments about CSA. */ | |
372 | ||
373 | GETSHORT(priority, p); | |
374 | GETSHORT(weight, p); | |
375 | GETSHORT(port, p); | |
376 | ||
377 | if (priority != 1) continue; /* CSA version must be 1 */ | |
378 | ||
379 | /* If the CSA record we found is not the one we asked for, analyse | |
380 | the subdomain assertions in the port field, else analyse the direct | |
381 | authorization status in the weight field. */ | |
382 | ||
383 | if (found != domain) | |
384 | { | |
385 | if (port & 1) *s = 'X'; /* explicit authorization required */ | |
386 | else *s = '?'; /* no subdomain assertions here */ | |
387 | } | |
388 | else | |
389 | { | |
390 | if (weight < 2) *s = 'N'; /* not authorized */ | |
391 | else if (weight == 2) *s = 'Y'; /* authorized */ | |
392 | else if (weight == 3) *s = '?'; /* unauthorizable */ | |
393 | else continue; /* invalid */ | |
394 | } | |
395 | ||
396 | s[1] = ' '; | |
397 | yield = string_cat(yield, &size, &ptr, s, 2); | |
398 | } | |
399 | ||
400 | /* GETSHORT() has advanced the pointer to the target domain. */ | |
8e669ac1 | 401 | |
7bb56e1f PH |
402 | rc = dn_expand(dnsa.answer, dnsa.answer + dnsa.answerlen, p, |
403 | (DN_EXPAND_ARG4_TYPE)(s), sizeof(s)); | |
8e669ac1 | 404 | |
7bb56e1f PH |
405 | /* If an overlong response was received, the data will have been |
406 | truncated and dn_expand may fail. */ | |
8e669ac1 | 407 | |
7bb56e1f PH |
408 | if (rc < 0) |
409 | { | |
410 | log_write(0, LOG_MAIN, "host name alias list truncated: type=%s " | |
411 | "domain=%s", dns_text_type(type), domain); | |
412 | break; | |
413 | } | |
414 | else yield = string_cat(yield, &size, &ptr, s, Ustrlen(s)); | |
0756eb3c | 415 | } |
7bb56e1f PH |
416 | } /* Loop for list of returned records */ |
417 | } /* Loop for list of domains */ | |
418 | ||
419 | /* Reclaim unused memory */ | |
0756eb3c | 420 | |
7bb56e1f PH |
421 | store_reset(yield + ptr + 1); |
422 | ||
8e669ac1 | 423 | /* If ptr == 0 we have not found anything. Otherwise, insert the terminating |
7bb56e1f PH |
424 | zero and return the result. */ |
425 | ||
c38d6da9 | 426 | if (ptr == 0) return failrc; |
0756eb3c | 427 | yield[ptr] = 0; |
0756eb3c | 428 | *result = yield; |
0756eb3c PH |
429 | return OK; |
430 | } | |
431 | ||
6545de78 PP |
432 | |
433 | ||
434 | /************************************************* | |
435 | * Version reporting entry point * | |
436 | *************************************************/ | |
437 | ||
438 | /* See local README for interface description. */ | |
439 | ||
440 | #include "../version.h" | |
441 | ||
442 | void | |
443 | dnsdb_version_report(FILE *f) | |
444 | { | |
445 | #ifdef DYNLOOKUP | |
446 | fprintf(f, "Library version: DNSDB: Exim version %s\n", EXIM_VERSION_STR); | |
447 | #endif | |
448 | } | |
449 | ||
450 | ||
e6d225ae DW |
451 | static lookup_info _lookup_info = { |
452 | US"dnsdb", /* lookup name */ | |
453 | lookup_querystyle, /* query style */ | |
454 | dnsdb_open, /* open function */ | |
455 | NULL, /* check function */ | |
456 | dnsdb_find, /* find function */ | |
457 | NULL, /* no close function */ | |
458 | NULL, /* no tidy function */ | |
6545de78 PP |
459 | NULL, /* no quoting function */ |
460 | dnsdb_version_report /* version reporting */ | |
e6d225ae DW |
461 | }; |
462 | ||
463 | #ifdef DYNLOOKUP | |
464 | #define dnsdb_lookup_module_info _lookup_module_info | |
465 | #endif | |
466 | ||
467 | static lookup_info *_lookup_list[] = { &_lookup_info }; | |
468 | lookup_module_info dnsdb_lookup_module_info = { LOOKUP_MODULE_INFO_MAGIC, _lookup_list, 1 }; | |
469 | ||
0756eb3c | 470 | /* End of lookups/dnsdb.c */ |