Julian Mehnle > Net-DNS-Resolver-Programmable-v0.003 > Net::DNS::Resolver::Programmable



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Module Version: 0.3.0   Source  


Net::DNS::Resolver::Programmable - programmable DNS resolver class for offline emulation of DNS




    use Net::DNS::Resolver::Programmable;
    use Net::DNS::RR;
    my $resolver = Net::DNS::Resolver::Programmable->new(
        records         => {
            'example.com'     => [
                Net::DNS::RR->new('example.com.     NS  ns.example.org.'),
                Net::DNS::RR->new('example.com.     A')
            'ns.example.org'  => [
                Net::DNS::RR->new('ns.example.org.  A')
        resolver_code   => sub {
            my ($domain, $rr_type, $class) = @_;
            return ($result, $aa, @rrs);


Net::DNS::Resolver::Programmable is a Net::DNS::Resolver descendant class that allows a virtual DNS to be emulated instead of querying the real DNS. A set of static DNS records may be supplied, or arbitrary code may be specified as a means for retrieving DNS records, or even generating them on the fly.


The following constructor is provided:

new(%options): returns Net::DNS::Resolver::Programmable

Creates a new programmed DNS resolver object.

%options is a list of key/value pairs representing any of the following options:


A reference to a hash of arrays containing a static set of Net::DNS::RR objects. The hash entries must be indexed by fully qualified domain names (lower-case, without any trailing dots), and the entries themselves must be arrays of the RR objects pertaining to these domain names. For example:

    records => {
        'example.com'     => [
            Net::DNS::RR->new('example.com.     NS  ns.example.org.'),
            Net::DNS::RR->new('example.com.     A')
        'www.example.com' => [
            Net::DNS::RR->new('www.example.com. A')
        'ns.example.org'  => [
            Net::DNS::RR->new('ns.example.org.  A')

If this option is specified, the resolver retrieves requested RRs from this data structure.


A code reference used as a call-back for dynamically retrieving requested RRs.

The code must take the following query parameters as arguments: the domain, RR type, and class.

It must return a list composed of: the response's RCODE (by name, as returned by Net::DNS::Header->rcode), the aa (authoritative answer) flag (boolean, use undef if you don't care), and the Net::DNS::RR answer objects. If an error string is returned instead of a valid RCODE, a Net::DNS::Packet object is not constructed but an error condition for the resolver is signaled instead.

For example:

    resolver_code => sub {
        my ($domain, $rr_type, $class) = @_;
        return ($result, $aa, @rrs);

If both this and the records option are specified, then statically programmed records are used in addition to any that are returned by the configured resolver code.


These Net::DNS::Resolver options are also meaningful with Net::DNS::Resolver::Programmable. See Net::DNS::Resolver for their descriptions.

Instance methods

The following instance methods of Net::DNS::Resolver are also supported by Net::DNS::Resolver::Programmable:

search: returns Net::DNS::Packet
query: returns Net::DNS::Packet
send: returns Net::DNS::Packet

Performs an offline DNS query, using the statically programmed DNS RRs and/or the configured dynamic resolver code. See the "new" constructor's records and resolver_code options. See the descriptions of search, query, and send for details about the calling syntax of these methods.

string: returns string
searchlist: returns list of string
defnames: returns boolean
dnsrch: returns boolean
debug: returns boolean
errorstring: returns string
answerfrom: returns string
answersize: returns integer

See "METHODS" in Net::DNS::Resolver.

Currently the following methods of Net::DNS::Resolver are not supported: axfr, axfr_start, axfr_next, nameservers, port, srcport, srcaddr, bgsend, bgread, bgisready, tsig, retrans, retry, recurse, usevc, tcp_timeout, udp_timeout, persistent_tcp, persistent_udp, igntc, dnssec, cdflag, udppacketsize. The effects of using these on Net::DNS::Resolver::Programmable objects are undefined.



For availability, support, and license information, see the README file included with Net::DNS::Resolver::Programmable.


Julian Mehnle <julian@mehnle.net>

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