171 lines
4.3 KiB
Perl
171 lines
4.3 KiB
Perl
package Mail::DKIM::Canonicalization::seal;
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use strict;
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use warnings;
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our $VERSION = '1.20230212'; # VERSION
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# ABSTRACT: arc seal canonicalization
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# Copyright 2017 FastMail Pty Ltd. All Rights Reserved.
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# Bron Gondwana <brong@fastmailteam.com>
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# This program is free software; you can redistribute it and/or
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# modify it under the same terms as Perl itself.
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# This canonicalization is for the ARC-Seal header from
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# https://tools.ietf.org/html/draft-ietf-dmarc-arc-protocol-06
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# Rather than having a 'h' property, it processes the headers in
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# a pre-defined way.
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#
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# 5.1.1.3. Deterministic (Implicit) 'h' Tag Value for ARC-Seal
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#
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# In this section, the term "scope" is used to indicate those header
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# fields signed by an ARC-Seal header field. A number in parentheses
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# indicates the instance of that field, starting at 1. The suffix "-
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# no-b" is used with an ARC-Seal field to indicate that its "b" field
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# is empty at the time the signature is computed, as described in
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# Section 3.5 of [RFC6376]. "AAR" refers to ARC-Authentication-
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# Results, "AMS" to ARC-Message-Signature, "AS" to ARC-Seal, and "ASB"
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# to an ARC-Seal with an empty "b" tag.
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#
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# Generally, the scope of an ARC set for a message containing "n" ARC
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# sets is the concatenation of the following, for x (instance number)
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# from 1 to n:
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#
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# o AAR(x);
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#
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# o AMS(x);
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#
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# o ASB(x) if x = n, else AS(x)
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#
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# Thus for a message with no seals (i.e., upon injection), the scope of
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# the first ARC set is AAR(1):AMS(1):ASB(1). The ARC set thus
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# generated would produce a first ARC-Seal with a "b" value. The next
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# ARC set would include in its signed content the prior scope, so it
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# would have a scope of AAR(1):AMS(1):AS(1):AAR(2):AMS(2):ASB(2).
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#
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# Note: Typically header field sets appear within the header in
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# descending instance order.
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use base 'Mail::DKIM::Canonicalization::relaxed';
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use Carp;
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sub init {
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my $self = shift;
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$self->SUPER::init;
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}
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sub _output_indexed_header {
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my ( $self, $headers, $h, $i ) = @_;
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foreach my $hdr (@$headers) {
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# this ugly pattern matches header: field; field; ... i=N
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next unless $hdr =~ m/^$h:\s*(?:[^;]*;\s*)*i=(\d+)/i and $1 == $i;
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$hdr =~ s/\015\012\z//s;
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$self->output( $self->canonicalize_header($hdr) . "\015\012" );
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return;
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}
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}
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sub finish_header {
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my $self = shift;
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my %args = @_;
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my $i = $self->{Signature}->identity();
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return unless $i =~ m{^\d+$}; # don't waste time if i= is bogus
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my $chain = $args{Chain};
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$chain = $self->{Signature}->chain() if ! defined $chain;
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# we include the seal for everything else
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# if the previous status was pass
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if ( $chain eq 'pass' ) {
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foreach my $n ( 1 .. ( $i - 1 ) ) {
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$self->_output_indexed_header( $args{Headers},
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'ARC-Authentication-Results', $n );
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$self->_output_indexed_header( $args{Headers},
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'ARC-Message-Signature', $n );
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$self->_output_indexed_header( $args{Headers}, 'ARC-Seal', $n );
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}
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}
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# always include this header set
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$self->_output_indexed_header( $args{Headers},
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'ARC-Authentication-Results', $i );
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$self->_output_indexed_header( $args{Headers}, 'ARC-Message-Signature',
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$i );
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# we don't add ARC-Seal at our index, because that is this signature, and it's
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# formed with standard DKIM style, so automatically appeneded
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}
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sub add_body {
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# no body add
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}
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1;
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__END__
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=pod
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=encoding UTF-8
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=head1 NAME
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Mail::DKIM::Canonicalization::seal - arc seal canonicalization
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=head1 VERSION
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version 1.20230212
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=head1 AUTHORS
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=over 4
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=item *
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Jason Long <jason@long.name>
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=item *
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Marc Bradshaw <marc@marcbradshaw.net>
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=item *
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Bron Gondwana <brong@fastmailteam.com> (ARC)
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=back
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=head1 THANKS
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Work on ensuring that this module passes the ARC test suite was
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generously sponsored by Valimail (https://www.valimail.com/)
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=head1 COPYRIGHT AND LICENSE
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=over 4
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=item *
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Copyright (C) 2013 by Messiah College
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=item *
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Copyright (C) 2010 by Jason Long
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=item *
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Copyright (C) 2017 by Standcore LLC
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=item *
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Copyright (C) 2020 by FastMail Pty Ltd
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=back
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This library is free software; you can redistribute it and/or modify
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it under the same terms as Perl itself, either Perl version 5.8.6 or,
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at your option, any later version of Perl 5 you may have available.
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=cut
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