-/* $Cambridge: exim/src/src/lookups/dnsdb.c,v 1.2 2004/11/19 09:45:54 ph10 Exp $ */
+/* $Cambridge: exim/src/src/lookups/dnsdb.c,v 1.6 2004/12/20 15:24:28 ph10 Exp $ */
/*************************************************
* Exim - an Internet mail transport agent *
#endif
"cname",
"mx",
+ "mxh",
"ns",
"ptr",
"srv",
#endif
T_CNAME,
T_MX,
+ T_MXH, /* Private type for "MX hostnames" */
T_NS,
T_PTR,
T_SRV,
* Find entry point for dnsdb *
*************************************************/
-/* See local README for interface description. */
+/* 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
+separator is newline.
+
+(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) 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
dnsdb_find(void *handle, uschar *filename, uschar *keystring, int length,
int rc;
int size = 256;
int ptr = 0;
+int sep = 0;
+int defer_mode = PASS;
int type = T_TXT;
-uschar *orig_keystring = keystring;
-uschar *equals = Ustrchr(keystring, '=');
+int failrc = FAIL;
+uschar *outsep = US"\n";
+uschar *equals, *domain;
uschar buffer[256];
/* Because we're the working in the search pool, we try to reclaim as much
length = length;
do_cache = do_cache;
-/* If the keystring contains an = this is preceded by a type name. */
+/* If the string starts with '>' we change the output separator */
-if (equals != NULL)
+while (isspace(*keystring)) keystring++;
+if (*keystring == '>')
{
- int i;
- int len = equals - keystring;
+ outsep = keystring + 1;
+ 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. */
+
+if ((equals = Ustrchr(keystring, '=')) != NULL)
+ {
+ int i, len;
+ uschar *tend = equals;
+
+ 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 += len + 1;
- }
-
-/* 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)
- {
- dns_build_reverse(keystring, buffer);
- keystring = buffer;
+
+ keystring = equals + 1;
+ while (isspace(*keystring)) keystring++;
}
-
-DEBUG(D_lookup) debug_printf("dnsdb key: %s\n", keystring);
-
-/* Initialize the resolver, in case this is the first time it is used
-in this run. Then do the lookup and sort out the result. */
+
+/* Initialize the resolver in case this is the first time it has been used. */
dns_init(FALSE, FALSE);
-rc = dns_special_lookup(&dnsa, keystring, type, NULL);
-
-if (rc == DNS_NOMATCH || rc == DNS_NODATA) return FAIL;
-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;
-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 newlines between
- them, just as for between several records. */
-
- if (type == T_A ||
- #ifdef SUPPORT_A6
- type == T_A6 ||
- #endif
- type == T_AAAA)
+/* 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
+it is treated as one item. */
+
+if (type == T_PTR && keystring[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)))
+ != 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. This code is now in a separate function. */
+
+ if (type == T_PTR)
{
- dns_address *da;
- for (da = dns_address_from_rr(&dnsa, rr); da != NULL; da = da->next)
- {
- if (ptr != 0) yield = string_cat(yield, &size, &ptr, US"\n", 1);
- yield = string_cat(yield, &size, &ptr, da->address, Ustrlen(da->address));
- }
- continue;
+ dns_build_reverse(domain, rbuffer);
+ domain = rbuffer;
}
-
- /* Other kinds of record just have one piece of data each. */
-
- if (ptr != 0) yield = string_cat(yield, &size, &ptr, US"\n", 1);
-
- if (type == T_TXT)
+
+ DEBUG(D_lookup) debug_printf("dnsdb key: %s\n", 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)
{
- yield = string_cat(yield, &size, &ptr, (uschar *)(rr->data+1),
- (rr->data)[0]);
+ 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 */
}
- else /* T_CNAME, T_MX, T_NS, T_PTR */
+
+ /* Search the returned records */
+
+ for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS);
+ rr != NULL;
+ rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT))
{
- uschar s[264];
- uschar *p = (uschar *)(rr->data);
- if (type == T_MX)
+ 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 ||
+ #endif
+ type == T_AAAA)
{
- int num;
- GETSHORT(num, p); /* pointer is advanced */
- sprintf(CS s, "%d ", num);
- yield = string_cat(yield, &size, &ptr, s, Ustrlen(s));
+ dns_address *da;
+ 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,
+ Ustrlen(da->address));
+ }
+ continue;
}
- else if (type == T_SRV)
+
+ /* 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)
{
- int num, 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));
+ yield = string_cat(yield, &size, &ptr, (uschar *)(rr->data+1),
+ (rr->data)[0]);
}
- 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)
+ else /* T_CNAME, T_MX, T_MXH, T_NS, T_SRV, T_PTR */
{
- log_write(0, LOG_MAIN, "host name alias list truncated for %s",
- orig_keystring);
- break;
+ int num;
+ uschar s[264];
+ uschar *p = (uschar *)(rr->data);
+
+ 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)
+ {
+ 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 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 "
+ "domain=%s", dns_text_type(type), domain);
+ break;
+ }
+ else yield = string_cat(yield, &size, &ptr, s, Ustrlen(s));
}
- else yield = string_cat(yield, &size, &ptr, s, Ustrlen(s));
- }
- }
+ } /* Loop for list of returned records */
+ } /* Loop for list of domains */
+
+/* Reclaim unused memory */
+store_reset(yield + ptr + 1);
+
+/* If ptr == 0 we have not found anything. Otherwise, insert the terminating
+zero and return the result. */
+
+if (ptr == 0) return failrc;
yield[ptr] = 0;
-store_reset(yield + ptr + 1); /* Reclaim unused */
*result = yield;
-
return OK;
}
projects / exim.git / blobdiff