NAME

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

SYNOPSIS

           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   192.168.0.1')
                   ],
                   'ns.example.org'  => [
                       Net::DNS::RR->new('ns.example.org.  A   192.168.1.1')
                   ]
               },

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

DESCRIPTION

       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.

   Constructor
       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:

           records
               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   192.168.0.1')
                       ],
                       'www.example.com' => [
                           Net::DNS::RR->new('www.example.com. A   192.168.0.2')
                       ],
                       'ns.example.org'  => [
                           Net::DNS::RR->new('ns.example.org.  A   192.168.1.1')
                       ]
                   }

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

           resolver_code
               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.

           defnames
           dnsrch
           domain
           searchlist
           debug
               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.

       print
       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.

SEE ALSO

       Net::DNS::Resolver

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

AUTHORS

       David Precious (BIGPRESH) "<davidp@preshweb.co.uk>" took on maintainership in July 2017

       Original author Julian Mehnle "<julian@mehnle.net>"

ACKNOWLEDGEMENTS

       Dick Franks (rwfranks)

       (This section was added by BIGPRESH in July 2017, so currently omits acknowledgements for
       those who contributed things in the past; I may retrospectively add them in future.)