Mail::SpamAssassin::DnsResolver(3)			User Contributed Perl Documentation			Mail::SpamAssassin::DnsResolver(3)

NAME

       Mail::SpamAssassin::DnsResolver - DNS resolution engine

DESCRIPTION

       This is a DNS resolution engine for SpamAssassin, implemented in order to reduce file descriptor usage by Net::DNS and avoid a response
       collision bug in that module.

METHODS

       $res->load_resolver()
	   Load the "Net::DNS::Resolver" object.  Returns 0 if Net::DNS cannot be used, 1 if it is available.

       $resolver = $res->get_resolver()
	   Return the "Net::DNS::Resolver" object.

       $res->nameservers()
	   Wrapper for Net::DNS::Resolver->nameservers to get or set list of nameservers

       $res->connect_sock()
	   Re-connect to the first nameserver listed in "/etc/resolv.conf" or similar platform-dependent source, as provided by "Net::DNS".

       $res->get_sock()
	   Return the "IO::Socket::INET" object used to communicate with the nameserver.

       $packet = new_dns_packet ($host, $type, $class)
	   A wrapper for "Net::DNS::Packet::new()" which traps a die thrown by it.

	   To use this, change calls to "Net::DNS::Resolver::bgsend" from:

	       $res->bgsend($hostname, $type);

	   to:

	       $res->bgsend(Mail::SpamAssassin::DnsResolver::new_dns_packet($hostname, $type, $class));

       $id = $res->bgsend($host, $type, $class, $cb)
	   Quite similar to "Net::DNS::Resolver::bgsend", except that when a response packet eventually arrives, and "poll_responses" is called,
	   the callback sub reference $cb will be called.

	   Note that $type and $class may be "undef", in which case they will default to "A" and "IN", respectively.

	   The callback sub will be called with three arguments -- the packet that was delivered, and an id string that fingerprints the query
	   packet and the expected reply. The third argument is a timestamp (Unix time, floating point), captured at the time the packet was
	   collected. It is expected that a closure callback be used, like so:

	     my $id = $self->{resolver}->bgsend($host, $type, undef, sub {
		   my ($reply, $reply_id, $timestamp) = @_;
		   $self->got_a_reply ($reply, $reply_id);
		 });

	   The callback can ignore the reply as an invalid packet sent to the listening port if the reply id does not match the return value from
	   bgsend.

       $nfound = $res->poll_responses()
	   See if there are any "bgsend" response packets ready, and return the number of such packets delivered to their callbacks.

       $res->bgabort()
	   Call this to release pending requests from memory, when aborting backgrounded requests, or when the scan is complete.
	   "Mail::SpamAssassin::PerMsgStatus::check" calls this before returning.

       $packet = $res->send($name, $type, $class)
	   Emulates "Net::DNS::Resolver::send()".

       $res->errorstring()
	   Little more than a stub for callers expecting this from "Net::DNS::Resolver".

	   If called immediately after a call to $res->send this will return "query timed out" if the $res->send DNS query timed out.  Otherwise
	   "unknown error or no error" will be returned.

	   No other errors are reported.

       $res->finish_socket()
	   Reset socket when done with it.

       $res->finish()
	   Clean up for destruction.

perl v5.16.3							    2011-06-06					Mail::SpamAssassin::DnsResolver(3)