/usr/share/perl5/Mail/SpamAssassin/Plugin/DNSEval.pm is in spamassassin 3.4.1-8build1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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# 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>
=head1 NAME
DNSEVAL - look up URLs against DNS blocklists
=cut
package Mail::SpamAssassin::Plugin::DNSEval;
use Mail::SpamAssassin::Plugin;
use Mail::SpamAssassin::Logger;
use Mail::SpamAssassin::Constants qw(:ip);
use Mail::SpamAssassin::Util qw(reverse_ip_address);
use strict;
use warnings;
use bytes;
use re 'taint';
use vars qw(@ISA);
@ISA = qw(Mail::SpamAssassin::Plugin);
# constructor: register the eval rule
sub new {
my $class = shift;
my $mailsaobject = shift;
# some boilerplate...
$class = ref($class) || $class;
my $self = $class->SUPER::new($mailsaobject);
bless ($self, $class);
# this is done this way so that the same list can be used here and in
# check_start()
$self->{'evalrules'} = [
'check_rbl_accreditor',
'check_rbl',
'check_rbl_txt',
'check_rbl_sub',
'check_rbl_results_for',
'check_rbl_from_host',
'check_rbl_from_domain',
'check_rbl_envfrom',
'check_dns_sender',
];
foreach(@{$self->{'evalrules'}}) {
$self->register_eval_rule($_);
}
return $self;
}
# this is necessary because PMS::run_rbl_eval_tests() calls these functions
# directly as part of PMS
sub check_start {
my ($self, $opts) = @_;
foreach(@{$self->{'evalrules'}}) {
$opts->{'permsgstatus'}->register_plugin_eval_glue($_);
}
}
sub ip_list_uniq_and_strip_private {
my ($self, @origips) = @_;
my @ips;
my %seen;
my $IP_PRIVATE = IP_PRIVATE;
foreach my $ip (@origips) {
next unless $ip;
next if (exists ($seen{$ip})); $seen{$ip} = 1;
next if ($ip =~ /$IP_PRIVATE/o);
push(@ips, $ip);
}
return @ips;
}
# check an RBL if the message contains an "accreditor assertion,"
# that is, the message contains the name of a service that will vouch
# for their practices.
#
sub check_rbl_accreditor {
my ($self, $pms, $rule, $set, $rbl_server, $subtest, $accreditor) = @_;
if (!defined $pms->{accreditor_tag}) {
$self->message_accreditor_tag($pms);
}
if ($pms->{accreditor_tag}->{$accreditor}) {
$self->check_rbl_backend($pms, $rule, $set, $rbl_server, 'A', $subtest);
}
return 0;
}
# Check for an Accreditor Assertion within the message, that is, the name of
# a third-party who will vouch for the sender's practices. The accreditor
# can be asserted in the EnvelopeFrom like this:
#
# listowner@a--accreditor.mail.example.com
#
# or in an 'Accreditor" Header field, like this:
#
# Accreditor: accreditor1, parm=value; accreditor2, parm-value
#
# This implementation supports multiple accreditors, but ignores any
# parameters in the header field.
#
sub message_accreditor_tag {
my ($self, $pms) = @_;
my %acctags;
if ($pms->get('EnvelopeFrom:addr') =~ /[@.]a--([a-z0-9]{3,})\./i) {
(my $tag = $1) =~ tr/A-Z/a-z/;
$acctags{$tag} = -1;
}
my $accreditor_field = $pms->get('Accreditor',undef);
if (defined $accreditor_field) {
my @accreditors = split(/,/, $accreditor_field);
foreach my $accreditor (@accreditors) {
my @terms = split(' ', $accreditor);
if ($#terms >= 0) {
my $tag = $terms[0];
$tag =~ tr/A-Z/a-z/;
$acctags{$tag} = -1;
}
}
}
$pms->{accreditor_tag} = \%acctags;
}
sub check_rbl_backend {
my ($self, $pms, $rule, $set, $rbl_server, $type, $subtest) = @_;
local ($_);
# First check that DNS is available, if not do not perform this check
return 0 if $self->{main}->{conf}->{skip_rbl_checks};
return 0 unless $pms->is_dns_available();
$pms->load_resolver();
if (($rbl_server !~ /^(\d+)\.(\d+)\.(\d+)\.(\d+)$/) &&
(index($rbl_server, '.') >= 0) &&
($rbl_server !~ /\.$/)) {
$rbl_server .= ".";
}
dbg("dns: checking RBL $rbl_server, set $set");
# ok, make a list of all the IPs in the untrusted set
my @fullips = map { $_->{ip} } @{$pms->{relays_untrusted}};
# now, make a list of all the IPs in the external set, for use in
# notfirsthop testing. This will often be more IPs than found
# in @fullips. It includes the IPs that are trusted, but
# not in internal_networks.
my @fullexternal = map {
(!$_->{internal}) ? ($_->{ip}) : ()
} @{$pms->{relays_trusted}};
push (@fullexternal, @fullips); # add untrusted set too
# Make sure a header significantly improves results before adding here
# X-Sender-Ip: could be worth using (very low occurance for me)
# X-Sender: has a very low bang-for-buck for me
my $IP_ADDRESS = IP_ADDRESS;
my @originating;
for my $header (@{$pms->{conf}->{originating_ip_headers}}) {
my $str = $pms->get($header,undef);
next unless defined $str && $str ne '';
push (@originating, ($str =~ m/($IP_ADDRESS)/g));
}
# Let's go ahead and trim away all private ips (KLC)
# also uniq the list and strip dups. (jm)
my @ips = $self->ip_list_uniq_and_strip_private(@fullips);
# if there's no untrusted IPs, it means we trust all the open-internet
# relays, so we can return right now.
return 0 unless (scalar @ips + scalar @originating > 0);
dbg("dns: IPs found: full-external: ".join(", ", @fullexternal).
" untrusted: ".join(", ", @ips).
" originating: ".join(", ", @originating));
my $trusted = $self->{main}->{conf}->{trusted_networks};
# If name is foo-notfirsthop, check all addresses except for
# the originating one. Suitable for use with dialup lists, like the PDL.
# note that if there's only 1 IP in the untrusted set, do NOT pop the
# list, since it'd remove that one, and a legit user is supposed to
# use their SMTP server (ie. have at least 1 more hop)!
# If name is foo-lastexternal, check only the Received header just before
# it enters our internal networks; we can trust it and it's the one that
# passed mail between networks
if ($set =~ /-(notfirsthop|lastexternal)$/)
{
# use the external IP set, instead of the trusted set; the user may have
# specified some third-party relays as trusted. Also, don't use
# @originating; those headers are added by a phase of relaying through
# a server like Hotmail, which is not going to be in dialup lists anyway.
@ips = $self->ip_list_uniq_and_strip_private(@fullexternal);
if ($1 eq "lastexternal") {
@ips = (defined $ips[0]) ? ($ips[0]) : ();
} else {
pop @ips if (scalar @ips > 1);
}
}
# If name is foo-firsttrusted, check only the Received header just
# after it enters our trusted networks; that's the only one we can
# trust the IP address from (since our relay added that header).
# And if name is foo-untrusted, check any untrusted IP address.
elsif ($set =~ /-(first|un)trusted$/)
{
my @tips;
foreach my $ip (@originating) {
if ($ip && !$trusted->contains_ip($ip)) {
push(@tips, $ip);
}
}
@ips = $self->ip_list_uniq_and_strip_private (@ips, @tips);
if ($1 eq "first") {
@ips = (defined $ips[0]) ? ($ips[0]) : ();
} else {
shift @ips;
}
}
else
{
my @tips;
foreach my $ip (@originating) {
if ($ip && !$trusted->contains_ip($ip)) {
push(@tips, $ip);
}
}
# add originating IPs as untrusted IPs (if they are untrusted)
@ips = reverse $self->ip_list_uniq_and_strip_private (@ips, @tips);
}
# How many IPs max you check in the received lines
my $checklast=$self->{main}->{conf}->{num_check_received};
if (scalar @ips > $checklast) {
splice (@ips, $checklast); # remove all others
}
my $tflags = $pms->{conf}->{tflags}->{$rule};
# Trusted relays should only be checked against nice rules (dnswls)
if (defined $tflags && $tflags !~ /\bnice\b/) {
# remove trusted hosts from beginning
while (@ips && $trusted->contains_ip($ips[0])) { shift @ips }
}
unless (scalar @ips > 0) {
dbg("dns: no untrusted IPs to check");
return 0;
}
dbg("dns: only inspecting the following IPs: ".join(", ", @ips));
eval {
foreach my $ip (@ips) {
my $revip = reverse_ip_address($ip);
$pms->do_rbl_lookup($rule, $set, $type,
$revip.'.'.$rbl_server, $subtest) if defined $revip;
}
};
# note that results are not handled here, hits are handled directly
# as DNS responses are harvested
return 0;
}
sub check_rbl {
my ($self, $pms, $rule, $set, $rbl_server, $subtest) = @_;
$self->check_rbl_backend($pms, $rule, $set, $rbl_server, 'A', $subtest);
}
sub check_rbl_txt {
my ($self, $pms, $rule, $set, $rbl_server, $subtest) = @_;
$self->check_rbl_backend($pms, $rule, $set, $rbl_server, 'TXT', $subtest);
}
# run for first message
sub check_rbl_sub {
my ($self, $pms, $rule, $set, $subtest) = @_;
return 0 if $self->{main}->{conf}->{skip_rbl_checks};
return 0 unless $pms->is_dns_available();
$pms->register_rbl_subtest($rule, $set, $subtest);
}
# backward compatibility
sub check_rbl_results_for {
#warn "dns: check_rbl_results_for() is deprecated, use check_rbl_sub()\n";
check_rbl_sub(@_);
}
# this only checks the address host name and not the domain name because
# using the domain name had much worse results for dsn.rfc-ignorant.org
sub check_rbl_from_host {
my ($self, $pms, $rule, $set, $rbl_server, $subtest) = @_;
_check_rbl_addresses($self, $pms, $rule, $set, $rbl_server, $subtest, $_[1]->all_from_addrs_domains());
}
=over 4
=item check_rbl_from_domain
This checks all the from addrs domain names as an alternate to check_rbl_from_host. As of v3.4.1, it has been improved to include a subtest for a specific octet.
=back
=cut
sub check_rbl_from_domain {
my ($self, $pms, $rule, $set, $rbl_server, $subtest) = @_;
_check_rbl_addresses($self, $pms, $rule, $set, $rbl_server, $subtest, $_[1]->all_from_addrs_domains());
}
# this only checks the address host name and not the domain name because
# using the domain name had much worse results for dsn.rfc-ignorant.org
sub check_rbl_envfrom {
my ($self, $pms, $rule, $set, $rbl_server, $subtest) = @_;
_check_rbl_addresses($self, $pms, $rule, $set, $rbl_server, $subtest, $_[1]->get('EnvelopeFrom:addr',undef));
}
sub _check_rbl_addresses {
my ($self, $pms, $rule, $set, $rbl_server, $subtest, @addresses) = @_;
return 0 if $self->{main}->{conf}->{skip_rbl_checks};
return 0 unless $pms->is_dns_available();
my %hosts;
for (@addresses) {
next if !defined($_) || !/ \@ ( [^\@\s]+ )/x;
my $address = $1;
# strip leading & trailing dots (as seen in some e-mail addresses)
$address =~ s/^\.+//; $address =~ s/\.+\z//;
# squash duplicate dots to avoid an invalid DNS query with a null label
$address =~ tr/.//s;
$hosts{lc($address)} = 1 if $address =~ /\./; # must by a FQDN
}
return unless scalar keys %hosts;
$pms->load_resolver();
if (($rbl_server !~ /^(\d+)\.(\d+)\.(\d+)\.(\d+)$/) &&
(index($rbl_server, '.') >= 0) &&
($rbl_server !~ /\.$/)) {
$rbl_server .= ".";
}
dbg("dns: _check_rbl_addresses RBL $rbl_server, set $set");
for my $host (keys %hosts) {
dbg("dns: checking [$host] / $rule / $set / $rbl_server");
$pms->do_rbl_lookup($rule, $set, 'A', "$host.$rbl_server", $subtest);
}
}
sub check_dns_sender {
my ($self, $pms, $rule) = @_;
my $host;
for my $from ($pms->get('EnvelopeFrom:addr',undef)) {
next unless defined $from;
$from =~ tr/././s; # bug 3366
if ($from =~ m/ \@ ( [^\@\s]+ \. [^\@\s]+ )/x ) {
$host = lc($1);
last;
}
}
return 0 unless defined $host;
# First check that DNS is available, if not do not perform this check
# TODO: need a way to skip DNS checks as a whole in configuration
return 0 unless $pms->is_dns_available();
$pms->load_resolver();
if ($host eq 'compiling.spamassassin.taint.org') {
# only used when compiling
return 0;
}
dbg("dns: checking A and MX for host $host");
$pms->do_dns_lookup($rule, 'A', $host);
$pms->do_dns_lookup($rule, 'MX', $host);
# cache name of host for later checking
$pms->{sender_host} = $host;
return 0;
}
1;
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