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->configured_nameservers()
           Get  a  list  of  nameservers  as  configured  by  dns_server  directives or as provided by Net::DNS,
           typically from /etc/resolv.conf

       $res->available_nameservers()
           Get or set a list of currently available nameservers, which is typically a known-to-be-good subset of
           configured 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.

       $packet = new_dns_packet ($domain, $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:

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

           to:

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

       $id = $res->bgsend($domain, $type, $class, $cb)
           DIRECT USE DISCOURAGED, please use bgsend_and_start_lookup in plugins.

           Quite similar to "Net::DNS::Resolver::bgsend", except that when a reply  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 = $self->{resolver}->bgsend($domain, $type, undef, sub {
                   my ($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.

       $id = $res->bgread()
           Similar to "Net::DNS::Resolver::bgread".  Reads a DNS packet from a supplied socket, decodes it,  and
           returns a Net::DNS::Packet object if successful.  Dies on error.

       $nfound = $res->poll_responses()
           See if there are any "bgsend" reply 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().

           This subroutine is a  simple  synchronous  leftover  from  SpamAssassin  version  3.3  and  does  not
           participate    in    packet    query    caching    and    callback   grouping   as   implemented   by
           AsyncLoop::bgsend_and_start_lookup().  As such it should be avoided for mainstream usage.   Currently
           used through Mail::SPF::Server by the SPF plugin.

       $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 v5.40.1                                       2025-06-26               Mail::SpamAssassin::DnsResolver(3pm)