&`fail`& keyword causes a &'forced expansion failure'& &-- see section
&<<SECTforexpfai>>& for an explanation of what this means.
-The supported DNS record types are A, CNAME, MX, NS, PTR, SPF, SRV, TLSA and TXT,
-and, when Exim is compiled with IPv6 support, AAAA.
-If no type is given, TXT is assumed. When the type is PTR,
-the data can be an IP address, written as normal; inversion and the addition of
-&%in-addr.arpa%& or &%ip6.arpa%& happens automatically. For example:
-.code
-${lookup dnsdb{ptr=192.168.4.5}{$value}fail}
-.endd
-If the data for a PTR record is not a syntactically valid IP address, it is not
-altered and nothing is added.
+The supported DNS record types are A, CNAME, MX, NS, PTR, SOA, SPF, SRV, TLSA
+and TXT, and, when Exim is compiled with IPv6 support, AAAA.
+If no type is given, TXT is assumed.
For any record type, if multiple records are found, the data is returned as a
concatenation, with newline as the default separator. The order, of course,
.endd
It is permitted to specify a space as the separator character. Further
white space is ignored.
+For lookup types that return multiple fields per record,
+an alternate field separator can be specified using a comma after the main
+separator character, followed immediately by the field separator.
+
+.cindex "PTR record" "in &(dnsdb)& lookup"
+When the type is PTR,
+the data can be an IP address, written as normal; inversion and the addition of
+&%in-addr.arpa%& or &%ip6.arpa%& happens automatically. For example:
+.code
+${lookup dnsdb{ptr=192.168.4.5}{$value}fail}
+.endd
+If the data for a PTR record is not a syntactically valid IP address, it is not
+altered and nothing is added.
.cindex "MX record" "in &(dnsdb)& lookup"
.cindex "SRV record" "in &(dnsdb)& lookup"
For an MX lookup, both the preference value and the host name are returned for
each record, separated by a space. For an SRV lookup, the priority, weight,
port, and host name are returned for each record, separated by spaces.
-An alternate field separator can be specified using a comma after the main
-separator character, followed immediately by the field separator.
+The field separator can be modified as above.
.cindex "TXT record" "in &(dnsdb)& lookup"
.cindex "SPF record" "in &(dnsdb)& lookup"
For TXT records with multiple items of data, only the first item is returned,
-unless a separator for them is specified using a comma after the separator
-character followed immediately by the TXT record item separator. To concatenate
-items without a separator, use a semicolon instead. For SPF records the
+unless a field separator is specified.
+To concatenate items without a separator, use a semicolon instead.
+For SPF records the
default behaviour is to concatenate multiple items without using a separator.
.code
${lookup dnsdb{>\n,: txt=a.b.example}}
It is permitted to specify a space as the separator character. Further
white space is ignored.
+.cindex "SOA record" "in &(dnsdb)& lookup"
+For an SOA lookup, while no result is obtained the lookup is redone with
+successively more leading components dropped from the given domain.
+Only the primary-nameserver field is returned unless a field separator is
+specified.
+.code
+${lookup dnsdb{>:,; soa=a.b.example.com}}
+.endd
+
.section "Dnsdb lookup modifiers" "SECTdnsdb_mod"
.cindex "dnsdb modifiers"
.cindex "modifiers" "dnsdb"
output a Distinguished Name string which is
not quite
parseable by Exim as a comma-separated tagged list
-(the exceptions being elements containin commas).
+(the exceptions being elements containing commas).
RDN elements of a single type may be selected by
a modifier of the type label; if so the expansion
result is a list (newline-separated by default).
.vitem &*${sort{*&<&'string'&>&*}{*&<&'comparator'&>&*}{*&<&'extractor'&>&*}}*&
-.cindex sorting a list
+.cindex sorting "a list"
.cindex list sorting
+.cindex expansion "list sorting"
After expansion, <&'string'&> is interpreted as a list, colon-separated by
default, but the separator can be changed in the usual way.
The <&'comparator'&> argument is interpreted as the operator
If an attempt to populate &$sender_host_name$& has been made
(by reference, &%hosts_lookup%& or
otherwise) then this boolean will have been set true if, and only if, the
-resolver library states that the reverse DNS was authenticated data. At all
+resolver library states that both
+the reverse and forward DNS were authenticated data. At all
other times, this variable is false.
It is likely that you will need to coerce DNSSEC support on in the resolver
Exim does not perform DNSSEC validation itself, instead leaving that to a
validating resolver (eg, unbound, or bind with suitable configuration).
-Exim does not (currently) check to see if the forward DNS was also secured
-with DNSSEC, only the reverse DNS.
-
If you have changed &%host_lookup_order%& so that &`bydns`& is not the first
mechanism in the list, then this variable will be false.
.cindex "DNS" "DNSSEC"
DNS lookups for domains matching &%dnssec_request_domains%& will be done with
the dnssec request bit set. Any returns not having the Authenticated Data bit
-(AD bit) set wil be ignored and logged as a host-lookup failure.
+(AD bit) set will be ignored and logged as a host-lookup failure.
This applies to all of the SRV, MX, AAAA, A lookup sequence.
git://git.exim.org / users / jgh / exim.git / blobdiff