# Copyright (C) 2016-2020 all contributors
# License: AGPL-3.0+
#
# base class for creating per-list or per-project filters
package PublicInbox::Filter::Base;
use strict;
use warnings;
use PublicInbox::MsgIter;
use parent qw(Exporter);
our @EXPORT_OK = qw(REJECT); # we may export IGNORE if/when needed
sub No ($) { "*** We only accept plain-text mail, No $_[0] ***" }
our %DEFAULTS = (
reject_suffix => [ qw(exe bat cmd com pif scr vbs cpl zip swf swfl) ],
reject_type => [ 'text/html:'.No('HTML'), 'text/xhtml:'.No('HTML'),
'application/vnd.*:'.No('vendor-specific formats'),
'image/*:'.No('images'), 'video/*:'.No('video'),
'audio/*:'.No('audio') ],
);
our $INVALID_FN = qr/\0/;
sub REJECT () { 100 }
sub ACCEPT { scalar @_ > 1 ? $_[1] : 1 }
sub IGNORE () { 0 }
my %patmap = ('*' => '.*', '?' => '.', '[' => '[', ']' => ']');
sub glob2pat {
my ($glob) = @_;
$glob =~ s!(.)!$patmap{$1} || "\Q$1"!ge;
$glob;
}
sub new {
my ($class, %opts) = @_;
my $self = bless { err => '', %opts }, $class;
foreach my $f (qw(reject_suffix reject_type)) {
# allow undef:
$self->{$f} = $DEFAULTS{$f} unless exists $self->{$f};
}
if (defined $self->{reject_suffix}) {
my $tmp = $self->{reject_suffix};
$tmp = join('|', map { glob2pat($_) } @$tmp);
$self->{reject_suffix} = qr/\.($tmp)\s*\z/i;
}
my $rt = [];
if (defined $self->{reject_type}) {
my $tmp = $self->{reject_type};
@$rt = map {
my ($type, $msg) = split(':', $_, 2);
$type = lc $type;
$msg ||= "Unacceptable Content-Type: $type";
my $re = glob2pat($type);
[ qr/\b$re\b/i, $msg ];
} @$tmp;
}
$self->{reject_type} = $rt;
$self;
}
sub reject ($$) {
my ($self, $reason) = @_;
$self->{err} = $reason;
REJECT;
}
sub err ($) { $_[0]->{err} }
# by default, scrub is a no-op, see PublicInbox::Filter::Vger::scrub
# for an example of the override. The $for_remove arg is set to
# disable altid setting for spam removal.
sub scrub {
my ($self, $mime, $for_remove) = @_;
$self->ACCEPT($mime);
}
# for MDA
sub delivery {
my ($self, $mime) = @_;
my $rt = $self->{reject_type};
my $reject_suffix = $self->{reject_suffix} || $INVALID_FN;
my (%sfx, %type);
msg_iter($mime, sub {
my ($part, $depth, @idx) = @{$_[0]};
my $ct = $part->content_type || 'text/plain';
foreach my $p (@$rt) {
if ($ct =~ $p->[0]) {
$type{$p->[1]} = 1;
}
}
my $fn = $part->filename;
if (defined($fn) && $fn =~ $reject_suffix) {
$sfx{$1} = 1;
}
});
my @r;
if (keys %type) {
push @r, sort keys %type;
}
if (keys %sfx) {
push @r, 'Rejected suffixes(s): '.join(', ', sort keys %sfx);
}
@r ? $self->reject(join("\n", @r)) : $self->scrub($mime);
}
1;