NAME

IO::Lambda::DNS - DNS queries lambda style

DESCRIPTION

The module provides access to asynchronous DNS queries through Net::DNS. Two function doing the same operation are featured: constructor new and condition dns.

SYNOPSIS

   use strict;
   use IO::Lambda::DNS qw(:all);
   use IO::Lambda qw(:all);
   
   # simple async query
   my $reply = IO::Lambda::DNS-> new( "www.site.com" )-> wait;
   print (($reply =~ /^\d/) ? "Resolved to $reply\n" : "Error: $reply\n");

   # parallel async queries
   lambda {
      for my $site ( map { "www.$_.com" } qw(google yahoo perl)) { 
         context $site, 'MX', timeout => 0.25; 
         dns { print shift-> string if ref($_[0]) }
      }
   }-> wait;

OPTIONS

Accepted options specific to the module are timeout or deadline (in seconds) and retry (in times). All other options, such as nameservers, dnssec etc etc are passed as is to the Net::DNS::Resolver constructor. See its man page for details.

USAGE

new

Constructor new accepts Net::DNS-specific options (see OPTIONS above) and query, and returns a lambda. The lambda accepts no parameters, and returns either an IP address or a response object (depending on the call syntax, see below), or an error string.

   new ($CLASS, %OPTIONS, $HOSTNAME) :: () -> ($IP_ADDRESS|$ERROR)

In the simple case, accepts $HOSTNAME string, and returns also a string, either an IP address or an error. To distinguish between these use /^\d/ regexp, because it is guaranteed that no error message will begin with a digit, and no IP address will begin with anything other than a digit.

   new (%OPTIONS, ($PACKET | $HOSTNAME, $TYPE)) :: () -> ($RESPONSE|$ERROR)

In the complex case, accepts either Net::DNS::Packet object, or $HOSTNAME and $TYPE strings, where the latter can be one of A, MX, etc DNS query type. See "bgsend" in Net::DNS::Resolver for the exact syntax.

Returns either a Net::DNS::RR object or an error string.

dns

Condition wrapper over new.

   dns (%OPTIONS, $HOSTNAME) -> $IP_ADDRESS|$ERROR
   dns (%OPTIONS, ($PACKET | $HOSTNAME $TYPE)) -> $RESPONSE|$ERROR

SEE ALSO

IO::Lambda, Net::DNS::Resolver.

AUTHOR

Dmitry Karasik, <dmitry@karasik.eu.org>.