Content-type: text/html Man page of Mail::SpamAssassin::DnsResolver

Mail::SpamAssassin::DnsResolver

Section: User Contributed Perl Documentation (3pm)
Updated: 2008-06-10
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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.


 

Index

NAME
DESCRIPTION
METHODS

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Time: 04:14:16 GMT, September 24, 2010