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# $Id: DecodeSRS.pm,v 1.2 2004/12/15 17:47:07 tvierling Exp $
#
# Copyright (c) 2002-2004 Todd Vierling <tv@pobox.com> <tv@duh.org>
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# 1. Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
#
# 2. Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
#
# 3. Neither the name of the author nor the names of contributors may be used
# to endorse or promote products derived from this software without specific
# prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
package Mail::Milter::Wrapper::DecodeSRS;
use 5.006;
use base Exporter;
use base Mail::Milter::Wrapper;
use strict;
use warnings;
use Carp;
use Mail::Milter::ContextWrapper;
use Sendmail::Milter 0.18; # get needed constants
our $VERSION = '0.02';
=pod
=head1 NAME
Mail::Milter::Wrapper::DecodeSRS - milter wrapper to decode SRS-encoded return path
=head1 SYNOPSIS
use Mail::Milter::Wrapper::DecodeSRS;
my $milter = ...;
my $wrapper = new Mail::Milter::Wrapper::DecodeSRS($milter);
my $wrapper2 = &DecodeSRS($milter); # convenience
=head1 DESCRIPTION
Mail::Milter::Wrapper::DecodeSRS is a convenience milter wrapper which
decodes MAIL FROM: return paths which have been encoded by the Sender
Rewrite Scheme, SRS. (More information: http://www.libsrs2.org/)
This wrapper internally understands both the SRS0 and SRS1 encoding
schemes documented by the Mail::SRS author.
The decoded address is made available to the contained milter via the
C<envfrom> callback, in the same way that a raw address would.
NOTE: If the address is not SRS encoded, the contained milter is NOT
called for the duration of the message; instead, SMFIS_ACCEPT is returned.
This is because the milter writer is expected to use this wrapper in a
chain that also includes the contained milter without wrapping, in order
to prevent a malicious sender from using SRS to bypass access checks.
For instance, the following is a proper usage of this wrapper in a chain:
my $envfrommilter = ...;
my $combinedmilter = new Mail::Milter::Chain(
new Mail::Milter::Wrapper::UnwrapSRS($envfrommilter),
$envfrommilter
);
This behavior can also be used if, e.g., the MTA already does one form of
MAIL FROM: check, and the contained milter repeats that same database
check against SRS rewritten addresses. (A good example would be a milter
emulating Sendmail's access_db map.)
=cut
our @EXPORT = qw(&DecodeSRS);
sub DecodeSRS {
new Mail::Milter::Wrapper::DecodeSRS(@_);
}
sub new ($$) {
my $this = Mail::Milter::Wrapper::new(shift, shift,
\&wrapper, qw{connect close});
$this;
}
# internal methods
sub wrapper {
my $this = shift;
my $cbname = shift;
my $callback_sub = shift;
if ($cbname eq 'envfrom') {
my $addr = $_[1];
# Mail::SRS::Guarded SRS1: strip to Mail::SRS::Guarded SRS0
$addr =~ s/^<SRS1[=\+-](?:[^=]+=)?[^=]+\.[^=]+=[=\+-]/SRS0=/;
if ($addr =~ /^<SRS0[=\+-][^=]+=(?:[^=]+=)?([^=]+\.[^=]+)=(.+)\@/) {
# Mail::SRS::Guarded SRS0
$_[1] = "<$2\@$1>";
} else {
return SMFIS_ACCEPT; # skip this message
}
}
&$callback_sub(@_);
}
1;
__END__
=head1 AUTHOR
Todd Vierling, E<lt>tv@duh.orgE<gt> E<lt>tv@pobox.comE<gt>
=head1 SEE ALSO
L<Mail::Milter::Wrapper>
=cut
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