-/* $Cambridge: exim/src/src/lookups/dnsdb.c,v 1.3 2004/11/19 15:18:57 ph10 Exp $ */
+/* $Cambridge: exim/src/src/lookups/dnsdb.c,v 1.10 2005/02/17 11:58:27 ph10 Exp $ */
/*************************************************
* Exim - an Internet mail transport agent *
*************************************************/
-/* Copyright (c) University of Cambridge 1995 - 2004 */
+/* Copyright (c) University of Cambridge 1995 - 2005 */
/* See the file NOTICE for conditions of use and distribution. */
#include "../exim.h"
#endif
"cname",
"mx",
+ "mxh",
"ns",
"ptr",
"srv",
"txt",
- "zns"
+ "zns"
};
static int type_values[] = {
#endif
T_CNAME,
T_MX,
+ T_MXH, /* Private type for "MX hostnames" */
T_NS,
T_PTR,
T_SRV,
/* See local README for interface description. The query in the "keystring" may
consist of a number of parts.
-(a) If the first significant character is '>' then the next character is the
-separator character that is used when multiple records are found. The default
+(a) If the first significant character is '>' then the next character is the
+separator character that is used when multiple records are found. The default
separator is newline.
-(b) If the next sequence of characters is a sequence of letters and digits
-followed by '=', it is interpreted as the name of the DNS record type. The
-default is "A".
+(b) If the next sequence of characters is 'defer_FOO' followed by a comma,
+the defer behaviour is set to FOO. The possible behaviours are: 'strict', where
+any defer causes the whole lookup to defer; 'lax', where a defer causes the
+whole lookup to defer only if none of the DNS queries succeeds; and 'never',
+where all defers are as if the lookup failed. The default is 'lax'.
-(c) Then there follows list of domain names. This is a generalized Exim list,
-which may start with '<' in order to set a specific separator. The default
+(c) If the next sequence of characters is a sequence of letters and digits
+followed by '=', it is interpreted as the name of the DNS record type. The
+default is "TXT".
+
+(d) Then there follows list of domain names. This is a generalized Exim list,
+which may start with '<' in order to set a specific separator. The default
separator, as always, is colon. */
int
int size = 256;
int ptr = 0;
int sep = 0;
+int defer_mode = PASS;
int type = T_TXT;
+int failrc = FAIL;
uschar *outsep = US"\n";
uschar *equals, *domain;
uschar buffer[256];
if (*keystring == '>')
{
outsep = keystring + 1;
- keystring += 2;
+ keystring += 2;
+ while (isspace(*keystring)) keystring++;
+ }
+
+/* Check for a defer behaviour keyword. */
+
+if (strncmpic(keystring, US"defer_", 6) == 0)
+ {
+ keystring += 6;
+ if (strncmpic(keystring, US"strict", 6) == 0)
+ {
+ defer_mode = DEFER;
+ keystring += 6;
+ }
+ else if (strncmpic(keystring, US"lax", 3) == 0)
+ {
+ defer_mode = PASS;
+ keystring += 3;
+ }
+ else if (strncmpic(keystring, US"never", 5) == 0)
+ {
+ defer_mode = OK;
+ keystring += 5;
+ }
+ else
+ {
+ *errmsg = US"unsupported dnsdb defer behaviour";
+ return DEFER;
+ }
+ while (isspace(*keystring)) keystring++;
+ if (*keystring++ != ',')
+ {
+ *errmsg = US"dnsdb defer behaviour syntax error";
+ return DEFER;
+ }
while (isspace(*keystring)) keystring++;
- }
+ }
/* If the keystring contains an = this must be preceded by a valid type name. */
{
int i, len;
uschar *tend = equals;
-
- while (tend > keystring && isspace(tend[-1])) tend--;
- len = tend - keystring;
-
+
+ while (tend > keystring && isspace(tend[-1])) tend--;
+ len = tend - keystring;
+
for (i = 0; i < sizeof(type_names)/sizeof(uschar *); i++)
{
if (len == Ustrlen(type_names[i]) &&
break;
}
}
-
+
if (i >= sizeof(type_names)/sizeof(uschar *))
{
*errmsg = US"unsupported DNS record type";
return DEFER;
}
-
+
keystring = equals + 1;
while (isspace(*keystring)) keystring++;
}
-
+
/* Initialize the resolver in case this is the first time it has been used. */
dns_init(FALSE, FALSE);
-/* The remainder of the string must be a list of domains. As long as the lookup
-for at least one of them succeeds, we return success. Failure means that none
-of them were found.
+/* The remainder of the string must be a list of domains. As long as the lookup
+for at least one of them succeeds, we return success. Failure means that none
+of them were found.
-The original implementation did not support a list of domains. Adding the list
-feature is compatible, except in one case: when PTR records are being looked up
-for a single IPv6 address. Fortunately, we can hack in a compatibility feature
-here: If the type is PTR and no list separator is specified, and the entire
-remaining string is valid as an IP address, set an impossible separator so that
+The original implementation did not support a list of domains. Adding the list
+feature is compatible, except in one case: when PTR records are being looked up
+for a single IPv6 address. Fortunately, we can hack in a compatibility feature
+here: If the type is PTR and no list separator is specified, and the entire
+remaining string is valid as an IP address, set an impossible separator so that
it is treated as one item. */
if (type == T_PTR && keystring[0] != '<' &&
- string_is_ip_address(keystring, NULL) > 0)
+ string_is_ip_address(keystring, NULL) > 0)
sep = -1;
/* Now scan the list and do a lookup for each item */
-while ((domain = string_nextinlist(&keystring, &sep, buffer, sizeof(buffer)))
+while ((domain = string_nextinlist(&keystring, &sep, buffer, sizeof(buffer)))
!= NULL)
- {
+ {
uschar rbuffer[256];
+ int searchtype = (type == T_ZNS)? T_NS : /* record type we want */
+ (type == T_MXH)? T_MX : type;
+
+ /* If the type is PTR, we have to construct the relevant magic lookup key if
+ the original is an IP address (some experimental protocols are using PTR
+ records for different purposes where the key string is a host name). This
+ code for doing the reversal is now in a separate function. */
- /* If the type is PTR, we have to construct the relevant magic lookup
- key. This code is now in a separate function. */
-
- if (type == T_PTR)
+ if (type == T_PTR && string_is_ip_address(domain, NULL) > 0)
{
dns_build_reverse(domain, rbuffer);
domain = rbuffer;
}
-
+
DEBUG(D_lookup) debug_printf("dnsdb key: %s\n", domain);
-
- /* Do the lookup and sort out the result. We use the special
- lookup function that knows about pseudo types like "zns". If the lookup
- fails, continue with the next domain. */
-
+
+ /* Do the lookup and sort out the result. There are two special types that
+ are handled specially: T_ZNS and T_MXH. The former is handled in a special
+ lookup function so that the facility could be used from other parts of the
+ Exim code. The latter affects only what happens later on in this function,
+ but for tidiness it is handled in a similar way. If the lookup fails,
+ continue with the next domain. In the case of DEFER, adjust the final
+ "nothing found" result, but carry on to the next domain. */
+
rc = dns_special_lookup(&dnsa, domain, type, NULL);
-
+
if (rc == DNS_NOMATCH || rc == DNS_NODATA) continue;
- if (rc != DNS_SUCCEED) return DEFER;
-
- /* If the lookup was a pseudo-type, change it to the correct type for
- searching the returned records; then search for them. */
-
- if (type == T_ZNS) type = T_NS;
+ if (rc != DNS_SUCCEED)
+ {
+ if (defer_mode == DEFER) return DEFER; /* always defer */
+ else if (defer_mode == PASS) failrc = DEFER; /* defer only if all do */
+ continue; /* treat defer as fail */
+ }
+
+ /* Search the returned records */
+
for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
rr != NULL;
rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
{
- if (rr->type != type) continue;
-
- /* There may be several addresses from an A6 record. Put the configured
- separator between them, just as for between several records. However, A6
+ if (rr->type != searchtype) continue;
+
+ /* There may be several addresses from an A6 record. Put the configured
+ separator between them, just as for between several records. However, A6
support is not normally configured these days. */
-
+
if (type == T_A ||
#ifdef SUPPORT_A6
type == T_A6 ||
for (da = dns_address_from_rr(&dnsa, rr); da != NULL; da = da->next)
{
if (ptr != 0) yield = string_cat(yield, &size, &ptr, outsep, 1);
- yield = string_cat(yield, &size, &ptr, da->address,
+ yield = string_cat(yield, &size, &ptr, da->address,
Ustrlen(da->address));
}
continue;
}
-
- /* Other kinds of record just have one piece of data each, but there may be
+
+ /* Other kinds of record just have one piece of data each, but there may be
several of them, of course. */
-
+
if (ptr != 0) yield = string_cat(yield, &size, &ptr, outsep, 1);
-
+
if (type == T_TXT)
{
yield = string_cat(yield, &size, &ptr, (uschar *)(rr->data+1),
(rr->data)[0]);
}
- else /* T_CNAME, T_MX, T_NS, T_SRV, T_PTR */
+ else /* T_CNAME, T_MX, T_MXH, T_NS, T_SRV, T_PTR */
{
+ int num;
uschar s[264];
uschar *p = (uschar *)(rr->data);
- if (type == T_MX)
+
+ if (type == T_MXH)
+ {
+ /* mxh ignores the priority number and includes only the hostnames */
+ GETSHORT(num, p); /* pointer is advanced */
+ }
+ else if (type == T_MX)
{
- int num;
GETSHORT(num, p); /* pointer is advanced */
sprintf(CS s, "%d ", num);
yield = string_cat(yield, &size, &ptr, s, Ustrlen(s));
}
else if (type == T_SRV)
{
- int num, weight, port;
+ int weight, port;
GETSHORT(num, p); /* pointer is advanced */
GETSHORT(weight, p);
GETSHORT(port, p);
sprintf(CS s, "%d %d %d ", num, weight, port);
yield = string_cat(yield, &size, &ptr, s, Ustrlen(s));
}
+
rc = dn_expand(dnsa.answer, dnsa.answer + dnsa.answerlen, p,
(DN_EXPAND_ARG4_TYPE)(s), sizeof(s));
-
+
/* If an overlong response was received, the data will have been
truncated and dn_expand may fail. */
-
+
if (rc < 0)
{
log_write(0, LOG_MAIN, "host name alias list truncated: type=%s "
store_reset(yield + ptr + 1);
-/* If ptr == 0 we have not found anything. Otherwise, insert the terminating
+/* If ptr == 0 we have not found anything. Otherwise, insert the terminating
zero and return the result. */
-if (ptr == 0) return FAIL;
+if (ptr == 0) return failrc;
yield[ptr] = 0;
*result = yield;
return OK;
git://git.exim.org / exim.git / blobdiff