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# <@LICENSE>
# Licensed to the Apache Software Foundation (ASF) under one or more
# contributor license agreements. See the NOTICE file distributed with
# this work for additional information regarding copyright ownership.
# The ASF licenses this file to you under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License. You may obtain a copy of the License at:
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# </@LICENSE>
package Mail::SpamAssassin::Header;
use strict;
use warnings FATAL => 'all';
use Exporter qw(import);
our @EXPORT = qw(_unfold_lines _remove_comments _replace_char);
=head1 NAME
Mail::SpamAssassin::Header - base class for SpamAssassin headers
=head1 SYNOPSIS
my $header = Mail::SpamAssassin::Header->new('raw header value');
print $header->value;
=head1 DESCRIPTION
This class is used to represent a generic header in SpamAssassin. It is used as a base class
for more specific header types.
=head1 METHODS
=over 4
=item new($raw)
Creates a new instance of the class. Accepts the raw header value as a string.
=cut
sub new {
my ($class,$raw) = @_;
my $self = bless {
raw => $raw,
}, $class;
return $self;
}
=item raw()
Returns the raw header value as a string.
=cut
sub raw { return $_[0]->{raw}; }
=item value()
Returns the header value as a string. For a generic header, this is the same as the raw value.
It is overridden in subclasses to provide more specific functionality.
=cut
sub value { return $_[0]->{raw}; }
sub _unfold_lines {
$_[0] =~ s/(?:\r\n|[\r\n])\s+/ /g;
}
#
# Remove comments from string
# - Comments are enclosed in parentheses ()
# - Comments can be nested
# - Backslash escapes the next character
# - Ignore comments in quoted strings
#
sub _remove_comments {
my $output = '';
my $level = 0;
my $removed = 0;
for(my $i=0; $i<length($_[0]); $i++) {
my $ch = substr($_[0],$i,1);
if ($ch eq '\\') {
$i++;
$output .= substr($_[0],$i,1) if $level == 0;
next;
}
if ($level == -1) {
# Inside quoted string
if ($ch eq '"') {
$level = 0;
}
} elsif ($level == 0) {
if ($ch eq '(') {
$level = 1;
$removed++;
next;
} elsif ($ch eq '"') {
$level = -1;
}
} else {
# Inside comment
if ($ch eq '(') {
$level++;
} elsif ($ch eq ')') {
$level--;
}
next;
}
$output .= $ch;
}
return 0 unless $removed;
# Remove extra whitespace left over by removing comments
$output =~ s/\s+/ /g;
$output =~ s/^\s+|\s+$//g;
$_[0] = $output;
return $removed;
}
#
# Replace characters in a string, but ignore those in quoted strings
#
sub _replace_char {
my ($find,$replace) = @_[1,2];
my $state = 0;
my $replacements = 0;
for(my $i=0; $i<length($_[0]); $i++) {
my $ch = substr($_[0],$i,1);
if ($ch eq '\\') {
$i++;
next;
}
if ($state == 0) {
if ($ch eq '"') {
$state = 1;
} elsif ( $ch eq $find ) {
substr($_[0],$i,1) = $replace;
$replacements++;
}
} elsif ($state == 1) {
if ($ch eq '"') {
$state = 0;
}
}
}
return $replacements;
}
=back
=cut
1;
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