1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2015 */
6 /* See the file NOTICE for conditions of use and distribution. */
9 #include "lf_functions.h"
13 /* Ancient systems (e.g. SunOS4) don't appear to have T_TXT defined in their
20 /* Many systems do not have T_SPF. */
25 /* New TLSA record for DANE */
30 /* Table of recognized DNS record types and their integer values. */
32 static const char *type_names
[] = {
52 static int type_values
[] = {
55 T_ADDRESSES
, /* Private type for AAAA + A */
59 T_CSA
, /* Private type for "Client SMTP Authorization". */
61 T_MXH
, /* Private type for "MX hostnames" */
69 T_ZNS
/* Private type for "zone nameservers" */
73 /*************************************************
75 *************************************************/
77 /* See local README for interface description. */
80 dnsdb_open(uschar
*filename
, uschar
**errmsg
)
82 filename
= filename
; /* Keep picky compilers happy */
83 errmsg
= errmsg
; /* Ditto */
84 return (void *)(-1); /* Any non-0 value */
89 /*************************************************
90 * Find entry point for dnsdb *
91 *************************************************/
93 /* See local README for interface description. The query in the "keystring" may
94 consist of a number of parts.
96 (a) If the first significant character is '>' then the next character is the
97 separator character that is used when multiple records are found. The default
100 (b) If the next character is ',' then the next character is the separator
101 character used for multiple items of text in "TXT" records. Alternatively,
102 if the next character is ';' then these multiple items are concatenated with
103 no separator. With neither of these options specified, only the first item
104 is output. Similarly for "SPF" records, but the default for joining multiple
105 items in one SPF record is the empty string, for direct concatenation.
107 (c) Options, all comma-terminated, in any order. Any unrecognised option
108 terminates option processing. Recognised options are:
110 - 'defer_FOO': set the defer behaviour to FOO. The possible behaviours are:
111 'strict', where any defer causes the whole lookup to defer; 'lax', where a defer
112 causes the whole lookup to defer only if none of the DNS queries succeeds; and
113 'never', where all defers are as if the lookup failed. The default is 'lax'.
115 - 'dnssec_FOO', with 'strict', 'lax' and 'never' (default). The meanings are
116 require, try and don't-try dnssec respectively.
118 - 'retrans_VAL', set the timeout value. VAL is an Exim time specification
119 (eg "5s"). The default is set by the main configuration option 'dns_retrans'.
121 - 'retry_VAL', set the retry count on timeouts. VAL is an integer. The
122 default is set by the main configuration option "dns_retry".
124 (d) If the next sequence of characters is a sequence of letters and digits
125 followed by '=', it is interpreted as the name of the DNS record type. The
128 (e) Then there follows list of domain names. This is a generalized Exim list,
129 which may start with '<' in order to set a specific separator. The default
130 separator, as always, is colon. */
133 dnsdb_find(void *handle
, uschar
*filename
, const uschar
*keystring
, int length
,
134 uschar
**result
, uschar
**errmsg
, uint
*do_cache
)
140 int defer_mode
= PASS
;
141 int dnssec_mode
= OK
;
142 int save_retrans
= dns_retrans
;
143 int save_retry
= dns_retry
;
146 const uschar
*outsep
= CUS
"\n";
147 const uschar
*outsep2
= NULL
;
148 uschar
*equals
, *domain
, *found
;
150 /* Because we're the working in the search pool, we try to reclaim as much
151 store as possible later, so we preallocate the result here */
153 uschar
*yield
= store_get(size
);
159 handle
= handle
; /* Keep picky compilers happy */
164 /* If the string starts with '>' we change the output separator.
165 If it's followed by ';' or ',' we set the TXT output separator. */
167 while (isspace(*keystring
)) keystring
++;
168 if (*keystring
== '>')
170 outsep
= keystring
+ 1;
172 if (*keystring
== ',')
174 outsep2
= keystring
+ 1;
177 else if (*keystring
== ';')
182 while (isspace(*keystring
)) keystring
++;
185 /* Check for a modifier keyword. */
189 if (strncmpic(keystring
, US
"defer_", 6) == 0)
192 if (strncmpic(keystring
, US
"strict", 6) == 0)
193 { defer_mode
= DEFER
; keystring
+= 6; }
194 else if (strncmpic(keystring
, US
"lax", 3) == 0)
195 { defer_mode
= PASS
; keystring
+= 3; }
196 else if (strncmpic(keystring
, US
"never", 5) == 0)
197 { defer_mode
= OK
; keystring
+= 5; }
200 *errmsg
= US
"unsupported dnsdb defer behaviour";
204 else if (strncmpic(keystring
, US
"dnssec_", 7) == 0)
207 if (strncmpic(keystring
, US
"strict", 6) == 0)
208 { dnssec_mode
= DEFER
; keystring
+= 6; }
209 else if (strncmpic(keystring
, US
"lax", 3) == 0)
210 { dnssec_mode
= PASS
; keystring
+= 3; }
211 else if (strncmpic(keystring
, US
"never", 5) == 0)
212 { dnssec_mode
= OK
; keystring
+= 5; }
215 *errmsg
= US
"unsupported dnsdb dnssec behaviour";
219 else if (strncmpic(keystring
, US
"retrans_", 8) == 0)
222 if ((timeout_sec
= readconf_readtime(keystring
+= 8, ',', FALSE
)) <= 0)
224 *errmsg
= US
"unsupported dnsdb timeout value";
227 dns_retrans
= timeout_sec
;
228 while (*keystring
!= ',') keystring
++;
230 else if (strncmpic(keystring
, US
"retry_", 6) == 0)
233 if ((retries
= (int)strtol(CCS keystring
+ 6, CSS
&keystring
, 0)) < 0)
235 *errmsg
= US
"unsupported dnsdb retry count";
243 while (isspace(*keystring
)) keystring
++;
244 if (*keystring
++ != ',')
246 *errmsg
= US
"dnsdb modifier syntax error";
249 while (isspace(*keystring
)) keystring
++;
252 /* Figure out the "type" value if it is not T_TXT.
253 If the keystring contains an = this must be preceded by a valid type name. */
256 if ((equals
= Ustrchr(keystring
, '=')) != NULL
)
259 uschar
*tend
= equals
;
261 while (tend
> keystring
&& isspace(tend
[-1])) tend
--;
262 len
= tend
- keystring
;
264 for (i
= 0; i
< sizeof(type_names
)/sizeof(uschar
*); i
++)
266 if (len
== Ustrlen(type_names
[i
]) &&
267 strncmpic(keystring
, US type_names
[i
], len
) == 0)
269 type
= type_values
[i
];
274 if (i
>= sizeof(type_names
)/sizeof(uschar
*))
276 *errmsg
= US
"unsupported DNS record type";
280 keystring
= equals
+ 1;
281 while (isspace(*keystring
)) keystring
++;
284 /* Initialize the resolver in case this is the first time it has been used. */
286 dns_init(FALSE
, FALSE
, dnssec_mode
!= OK
);
288 /* The remainder of the string must be a list of domains. As long as the lookup
289 for at least one of them succeeds, we return success. Failure means that none
292 The original implementation did not support a list of domains. Adding the list
293 feature is compatible, except in one case: when PTR records are being looked up
294 for a single IPv6 address. Fortunately, we can hack in a compatibility feature
295 here: If the type is PTR and no list separator is specified, and the entire
296 remaining string is valid as an IP address, set an impossible separator so that
297 it is treated as one item. */
299 if (type
== T_PTR
&& keystring
[0] != '<' &&
300 string_is_ip_address(keystring
, NULL
) != 0)
303 /* SPF strings should be concatenated without a separator, thus make
304 it the default if not defined (see RFC 4408 section 3.1.3).
305 Multiple SPF records are forbidden (section 3.1.2) but are currently
306 not handled specially, thus they are concatenated with \n by default.
307 MX priority and value are space-separated by default.
308 SRV and TLSA record parts are space-separated by default. */
310 if (!outsep2
) switch(type
)
312 case T_SPF
: outsep2
= US
""; break;
313 case T_SRV
: case T_MX
: case T_TLSA
: outsep2
= US
" "; break;
316 /* Now scan the list and do a lookup for each item */
318 while ((domain
= string_nextinlist(&keystring
, &sep
, NULL
, 0)))
321 int searchtype
= (type
== T_CSA
)? T_SRV
: /* record type we want */
322 (type
== T_MXH
)? T_MX
:
323 (type
== T_ZNS
)? T_NS
: type
;
325 /* If the type is PTR or CSA, we have to construct the relevant magic lookup
326 key if the original is an IP address (some experimental protocols are using
327 PTR records for different purposes where the key string is a host name, and
328 Exim's extended CSA can be keyed by domains or IP addresses). This code for
329 doing the reversal is now in a separate function. */
331 if ((type
== T_PTR
|| type
== T_CSA
) &&
332 string_is_ip_address(domain
, NULL
) != 0)
334 dns_build_reverse(domain
, rbuffer
);
340 DEBUG(D_lookup
) debug_printf("dnsdb key: %s\n", domain
);
342 /* Do the lookup and sort out the result. There are four special types that
343 are handled specially: T_CSA, T_ZNS, T_ADDRESSES and T_MXH.
344 The first two are handled in a special lookup function so that the facility
345 could be used from other parts of the Exim code. T_ADDRESSES is handled by looping
346 over the types of A lookup. T_MXH affects only what happens later on in
347 this function, but for tidiness it is handled by the "special". If the
348 lookup fails, continue with the next domain. In the case of DEFER, adjust
349 the final "nothing found" result, but carry on to the next domain. */
353 if (type
== T_ADDRESSES
) /* NB cannot happen unless HAVE_IPV6 */
355 if (searchtype
== T_ADDRESSES
) searchtype
= T_AAAA
;
356 else if (searchtype
== T_AAAA
) searchtype
= T_A
;
357 rc
= dns_special_lookup(&dnsa
, domain
, searchtype
, CUSS
&found
);
361 rc
= dns_special_lookup(&dnsa
, domain
, type
, CUSS
&found
);
363 lookup_dnssec_authenticated
= dnssec_mode
==OK
? NULL
364 : dns_is_secure(&dnsa
) ? US
"yes" : US
"no";
366 if (rc
== DNS_NOMATCH
|| rc
== DNS_NODATA
) continue;
367 if ( rc
!= DNS_SUCCEED
368 || (dnssec_mode
== DEFER
&& !dns_is_secure(&dnsa
))
371 if (defer_mode
== DEFER
)
373 dns_retrans
= save_retrans
;
374 dns_retry
= save_retry
;
375 dns_init(FALSE
, FALSE
, FALSE
); /* clr dnssec bit */
376 return DEFER
; /* always defer */
378 if (defer_mode
== PASS
) failrc
= DEFER
; /* defer only if all do */
379 continue; /* treat defer as fail */
383 /* Search the returned records */
385 for (rr
= dns_next_rr(&dnsa
, &dnss
, RESET_ANSWERS
);
387 rr
= dns_next_rr(&dnsa
, &dnss
, RESET_NEXT
))
389 if (rr
->type
!= searchtype
) continue;
391 if (*do_cache
> rr
->ttl
)
394 if (type
== T_A
|| type
== T_AAAA
|| type
== T_ADDRESSES
)
397 for (da
= dns_address_from_rr(&dnsa
, rr
); da
; da
= da
->next
)
399 if (ptr
!= 0) yield
= string_cat(yield
, &size
, &ptr
, outsep
, 1);
400 yield
= string_cat(yield
, &size
, &ptr
, da
->address
,
401 Ustrlen(da
->address
));
406 /* Other kinds of record just have one piece of data each, but there may be
407 several of them, of course. */
409 if (ptr
!= 0) yield
= string_cat(yield
, &size
, &ptr
, outsep
, 1);
411 if (type
== T_TXT
|| type
== T_SPF
)
415 /* output only the first item of data */
416 yield
= string_cat(yield
, &size
, &ptr
, (uschar
*)(rr
->data
+1),
421 /* output all items */
423 while (data_offset
< rr
->size
)
425 uschar chunk_len
= (rr
->data
)[data_offset
++];
426 if (outsep2
[0] != '\0' && data_offset
!= 1)
427 yield
= string_cat(yield
, &size
, &ptr
, outsep2
, 1);
428 yield
= string_cat(yield
, &size
, &ptr
,
429 (uschar
*)((rr
->data
)+data_offset
), chunk_len
);
430 data_offset
+= chunk_len
;
434 else if (type
== T_TLSA
)
436 uint8_t usage
, selector
, matching_type
;
437 uint16_t i
, payload_length
;
438 uschar s
[MAX_TLSA_EXPANDED_SIZE
];
440 uschar
* p
= US rr
->data
;
444 matching_type
= *p
++;
445 /* What's left after removing the first 3 bytes above */
446 payload_length
= rr
->size
- 3;
447 sp
+= sprintf(CS s
, "%d%c%d%c%d%c", usage
, *outsep2
,
448 selector
, *outsep2
, matching_type
, *outsep2
);
449 /* Now append the cert/identifier, one hex char at a time */
451 i
< payload_length
&& sp
-s
< (MAX_TLSA_EXPANDED_SIZE
- 4);
453 sp
+= sprintf(CS sp
, "%02x", (unsigned char)p
[i
]);
455 yield
= string_cat(yield
, &size
, &ptr
, s
, Ustrlen(s
));
457 else /* T_CNAME, T_CSA, T_MX, T_MXH, T_NS, T_PTR, T_SOA, T_SRV */
459 int priority
, weight
, port
;
461 uschar
* p
= US rr
->data
;
466 /* mxh ignores the priority number and includes only the hostnames */
467 GETSHORT(priority
, p
);
471 GETSHORT(priority
, p
);
472 sprintf(CS s
, "%d%c", priority
, *outsep2
);
473 yield
= string_cat(yield
, &size
, &ptr
, s
, Ustrlen(s
));
477 GETSHORT(priority
, p
);
480 sprintf(CS s
, "%d%c%d%c%d%c", priority
, *outsep2
,
481 weight
, *outsep2
, port
, *outsep2
);
482 yield
= string_cat(yield
, &size
, &ptr
, s
, Ustrlen(s
));
486 /* See acl_verify_csa() for more comments about CSA. */
487 GETSHORT(priority
, p
);
491 if (priority
!= 1) continue; /* CSA version must be 1 */
493 /* If the CSA record we found is not the one we asked for, analyse
494 the subdomain assertions in the port field, else analyse the direct
495 authorization status in the weight field. */
497 if (Ustrcmp(found
, domain
) != 0)
499 if (port
& 1) *s
= 'X'; /* explicit authorization required */
500 else *s
= '?'; /* no subdomain assertions here */
504 if (weight
< 2) *s
= 'N'; /* not authorized */
505 else if (weight
== 2) *s
= 'Y'; /* authorized */
506 else if (weight
== 3) *s
= '?'; /* unauthorizable */
507 else continue; /* invalid */
511 yield
= string_cat(yield
, &size
, &ptr
, s
, 2);
518 /* GETSHORT() has advanced the pointer to the target domain. */
520 rc
= dn_expand(dnsa
.answer
, dnsa
.answer
+ dnsa
.answerlen
, p
,
521 (DN_EXPAND_ARG4_TYPE
)s
, sizeof(s
));
523 /* If an overlong response was received, the data will have been
524 truncated and dn_expand may fail. */
528 log_write(0, LOG_MAIN
, "host name alias list truncated: type=%s "
529 "domain=%s", dns_text_type(type
), domain
);
532 else yield
= string_cat(yield
, &size
, &ptr
, s
, Ustrlen(s
));
534 if (type
== T_SOA
&& outsep2
!= NULL
)
536 unsigned long serial
, refresh
, retry
, expire
, minimum
;
539 yield
= string_cat(yield
, &size
, &ptr
, outsep2
, 1);
541 rc
= dn_expand(dnsa
.answer
, dnsa
.answer
+ dnsa
.answerlen
, p
,
542 (DN_EXPAND_ARG4_TYPE
)s
, sizeof(s
));
545 log_write(0, LOG_MAIN
, "responsible-mailbox truncated: type=%s "
546 "domain=%s", dns_text_type(type
), domain
);
549 else yield
= string_cat(yield
, &size
, &ptr
, s
, Ustrlen(s
));
552 GETLONG(serial
, p
); GETLONG(refresh
, p
);
553 GETLONG(retry
, p
); GETLONG(expire
, p
); GETLONG(minimum
, p
);
554 sprintf(CS s
, "%c%lu%c%lu%c%lu%c%lu%c%lu",
555 *outsep2
, serial
, *outsep2
, refresh
,
556 *outsep2
, retry
, *outsep2
, expire
, *outsep2
, minimum
);
557 yield
= string_cat(yield
, &size
, &ptr
, s
, Ustrlen(s
));
560 } /* Loop for list of returned records */
562 /* Loop for set of A-lookupu types */
563 } while (type
== T_ADDRESSES
&& searchtype
!= T_A
);
565 } /* Loop for list of domains */
567 /* Reclaim unused memory */
569 store_reset(yield
+ ptr
+ 1);
571 /* If ptr == 0 we have not found anything. Otherwise, insert the terminating
572 zero and return the result. */
574 dns_retrans
= save_retrans
;
575 dns_retry
= save_retry
;
576 dns_init(FALSE
, FALSE
, FALSE
); /* clear the dnssec bit for getaddrbyname */
578 if (ptr
== 0) return failrc
;
586 /*************************************************
587 * Version reporting entry point *
588 *************************************************/
590 /* See local README for interface description. */
592 #include "../version.h"
595 dnsdb_version_report(FILE *f
)
598 fprintf(f
, "Library version: DNSDB: Exim version %s\n", EXIM_VERSION_STR
);
603 static lookup_info _lookup_info
= {
604 US
"dnsdb", /* lookup name */
605 lookup_querystyle
, /* query style */
606 dnsdb_open
, /* open function */
607 NULL
, /* check function */
608 dnsdb_find
, /* find function */
609 NULL
, /* no close function */
610 NULL
, /* no tidy function */
611 NULL
, /* no quoting function */
612 dnsdb_version_report
/* version reporting */
616 #define dnsdb_lookup_module_info _lookup_module_info
619 static lookup_info
*_lookup_list
[] = { &_lookup_info
};
620 lookup_module_info dnsdb_lookup_module_info
= { LOOKUP_MODULE_INFO_MAGIC
, _lookup_list
, 1 };
624 /* End of lookups/dnsdb.c */