Performs dns queries for mail::dkim
This is the module that performs \s-1DNS\s0 queries for Mail::DKIM.
This module has a couple configuration settings that the caller may want to use to customize the behavior of this module. This global variable specifies the maximum amount of time (in seconds) to wait for a single \s-1DNS\s0 query to complete. The default is 10.
Use this global subroutine to get or replace the instance of Net::DNS::Resolver that Mail::DKIM uses. If set to undef (the default), then a brand new default instance of Net::DNS::Resolver will be created the first time a \s-1DNS\s0 query is needed.
You will call this subroutine if you want to specify non-default options to Net::DNS::Resolver, such as different timeouts, or to enable use of a persistent socket. For example:
# first, construct a custom DNS resolver
my $res = Net::DNS::Resolver->new(
udp_timeout => 3, tcp_timeout => 3, retry => 2,
);
$res->udppacketsize(1240);
$res->persistent_udp(1);
# then, tell Mail::DKIM to use this resolver
Mail::DKIM::DNS::resolver($res);
This is a convenience subroutine that will construct an appropriate \s-1DNS\s0 resolver that uses \s-1EDNS0\s0 (Extension mechanisms for \s-1DNS\s0) to support large \s-1DNS\s0 replies, and configure Mail::DKIM to use it. (As such, it should \s-1NOT\s0 be used in conjunction with the resolver() subroutine described above.)
Mail::DKIM::DNS::enable_EDNS0();
Use of \s-1EDNS0\s0 is recommended, since it reduces the need for falling back to \s-1TCP\s0 when dealing with large \s-1DNS\s0 packets. However, it is not enabled by default because some Internet firewalls which do deep inspection of packets are not able to process EDNS0-enabled packets. When there is a firewall on a path to a \s-1DNS\s0 resolver, the \s-1EDNS0\s0 feature should be specifically tested before enabling.
Jason Long, <[email protected]>
Copyright (C) 2006-2007, 2012-2013 by Messiah College
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.6 or, at your option, any later version of Perl 5 you may have available.