Mail::DKIM::SignerPolicy (3pm)

A \*(L"signer policy\*(R" is an object, class, or function used by Mail::DKIM::Signer to determine what signatures to add to the current message. To take advantage of signer policies, create your own Perl class that extends the Mail::DKIM::SignerPolicy class. The only method you need to implement is the apply() method.

The apply() method takes as a parameter the Mail::DKIM::Signer object. Using this object, it can determine some properties of the message (e.g. what the From: address or Sender: address is). Then it sets various signer properties as desired. The apply() method should return a nonzero value if the message should be signed. If a false value is returned, then the message is \*(L"skipped\*(R" (i.e. not signed).

Here is an example of a policy that always returns the same values:

  package MySignerPolicy;
  use base "Mail::DKIM::SignerPolicy";

  sub apply
  {
      my $self = shift;
      my $signer = shift;

      $signer->algorithm("rsa-sha1");
      $signer->method("relaxed");
      $signer->domain("example.org");
      $signer->selector("selector1");
      $signer->key_file("private.key");

      return 1;
  }

To use this policy, simply specify the name of the class as the Policy parameter...

my $dkim = Mail::DKIM::Signer->new( Policy => "MySignerPolicy", );

You can also have the policy actually build the signature for the Signer to use. To do this, call the signer's add_signature() method from within your apply() callback. E.g.,

sub apply { my $self = shift; my $signer = shift;

$signer->add_signature( new Mail::DKIM::Signature( Algorithm => $signer->algorithm, Method => $signer->method, Headers => $signer->headers, Domain => $signer->domain, Selector => $signer->selector, )); return; }

Again, if you do not want any signatures, return zero or undef. If you use add_signature() to create a signature, the default signature will not be created, even if you return nonzero.

Jason Long, <[email protected]>

Copyright (C) 2006-2007 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.