dspam: a batch of improvements:
expanded POD
cleaned up stray EOL spaces
added lots of logging, with standardized [ pass | fail | skip ] prefixes
added reject_type option
use split for parsing dspam headers
use SA note instead of parsing headers
added reject = agree option
store & fetch dspam results in a note
---
plugins/dspam | 247 +++++++++++++++++++++++++++++++-------------------
t/plugin_tests/dspam | 97 ++++++++++++++++++++
2 files changed, 252 insertions(+), 92 deletions(-)
create mode 100644 t/plugin_tests/dspam
diff --git a/plugins/dspam b/plugins/dspam
index cd797f1..337fd59 100644
--- a/plugins/dspam
+++ b/plugins/dspam
@@ -6,18 +6,25 @@ dspam - dspam integration for qpsmtpd
=head1 DESCRIPTION
-qpsmtpd plugin that uses dspam to classify messages. Can use SpamAssassin to
+qpsmtpd plugin that uses dspam to classify messages. Can use SpamAssassin to
train dspam.
-Adds the X-DSPAM-Result and X-DSPAM-Signature headers to messages. The latter
is essential for
+Adds the X-DSPAM-Result and X-DSPAM-Signature headers to messages. The latter
is essential for
training dspam and the former is useful to MDAs, MUAs, and humans.
+Adds a transaction note to the qpsmtpd transaction. The notes is a hashref
+with at least the 'class' field (Spam,Innocent,Whitelisted). It will normally
+contain a probability and confidence ratings as well.
+
=head1 TRAINING DSPAM
+Do not just enable dspam! Its false positive rate when untrained is high. The
+good news is; dspam learns very, very fast.
+
To get dspam into a useful state, it must be trained. The best method way to
train dspam is to feed it two large equal sized corpuses of spam and ham from
-your mail server. The dspam authors suggest avoiding public corpuses. I do
-this as follows:
+your mail server. The dspam authors suggest avoiding public corpuses. I train
+dspam as follows:
=over 4
@@ -25,34 +32,31 @@ this as follows:
See the docs on the learn_from_sa feature in the CONFIG section.
-=item daily training
+=item periodic training
-I have a script that crawls the contents of every users maildir each night.
-The script builds two lists of messages: ham and spam.
-
-The spam message list consists of all read messages in folders named Spam
-that have changed since the last spam learning run (normally 1 day).
+I have a script that searches the contents of every users maildir. Any read
+messages that have changed since the last processing run are learned as ham
+or spam.
The ham message list consists of read messages in any folder not named like
-Spam, Junk, Trash, or Deleted. This catches messages that users have read
-and left in their inbox, filed away into subfolders, and
+Spam, Junk, Trash, or Deleted. This catches messages that users have read
+and left in their inbox or filed away into subfolders.
=item on-the-fly training
-=back
-
+The dovecot IMAP server has an antispam plugin that will train dspam when
+messages are moved to/from the Spam folder.
+=back
=head1 CONFIG
-=over 4
-
-=item dspam_bin
+=head2 dspam_bin
-The path to the dspam binary. If yours is installed somewhere other
+The path to the dspam binary. If yours is installed somewhere other
than /usr/local/bin/dspam, you'll need to set this.
-=item learn_from_sa
+=head2 learn_from_sa
Dspam can be trained by SpamAssassin. This relationship between them requires
attention to several important details:
@@ -61,7 +65,7 @@ attention to several important details:
=item 1
-dspam must be listed B<after> spamassassin in the config/plugins file.
+dspam must be listed B<after> spamassassin in the config/plugins file.
Because SA runs first, I crank the SA reject_threshold up above 100 so that
all spam messages will be used to train dspam.
@@ -72,9 +76,9 @@ reduce the SA load.
Autolearn must be enabled and configured in SpamAssassin. SA autolearn
preferences will determine whether a message is learned as spam or innocent
-by dspam. The settings to pay careful attention to in your SA local.cf file
+by dspam. The settings to pay careful attention to in your SA local.cf file
are bayes_auto_learn_threshold_spam and bayes_auto_learn_threshold_nonspam.
-Make sure they are both set to conservative values that are certain to
+Make sure they are both set to conservative values that are certain to
yield no false positives.
If you are using learn_from_sa and reject, then messages that exceed the SA
@@ -84,7 +88,7 @@ autolearn threshholds are set high enough to avoid false
positives.
=item 3
dspam must be configured and working properly. I have modified the following
-dspam values on my system:
+dspam values on my system:
=over 4
@@ -113,18 +117,26 @@ only supports storing the signature in the headers. If
you want to train dspam
after delivery (ie, users moving messages to/from spam folders), then the
dspam signature must be in the headers.
+When using the dspam MySQL backend, use InnoDB tables. Dspam training
+is dramatically slowed by MyISAM table locks and dspam requires lots
+of training. InnoDB has row level locking and updates are much faster.
+
=back
-=item reject
+=head2 reject
Set to a floating point value between 0 and 1.00 where 0 is no confidence
and 1.0 is 100% confidence.
-If dspam's confidence is greater than or equal to this threshold, the
-message will be rejected.
+If dspam's confidence is greater than or equal to this threshold, the
+message will be rejected. The default is 1.00.
-=back
+=head2 reject_type
+
+ reject_type [ temp | perm ]
+By default, rejects are permanent (5xx). Set this to temp if you want to
+defer mail instead of rejecting it with dspam.
=head1 MULTIPLE RECIPIENT BEHAVIOR
@@ -139,9 +151,14 @@ ie, (Trust smtpd).
=head1 CHANGES
+=head1 AUTHOR
+
+ Matt Simerson - 2012
+
=cut
use strict;
+use warnings;
use Qpsmtpd::Constants;
use Qpsmtpd::DSN;
@@ -149,43 +166,46 @@ use IO::Handle;
use Socket qw(:DEFAULT :crlf);
sub register {
- my ($self, $qp, @args) = @_;
+ my ($self, $qp, %args) = @_;
$self->log(LOGERROR, "Bad parameters for the dspam plugin") if @_ % 2;
- %{$self->{_args}} = @args;
+ $self->{_args} = { %args };
+ $self->{_args}{reject} = defined $args{reject} ? $args{reject} : 1;
+ $self->{_args}{reject_type} = $args{reject_type} || 'perm';
- $self->register_hook('data_post', 'dspam_reject')
- if $self->{_args}->{reject};
+ $self->register_hook('data_post', 'dspam_reject');
}
sub hook_data_post {
my ($self, $transaction) = @_;
$self->log(LOGDEBUG, "check_dspam");
- return (DECLINED) if $transaction->data_size > 500_000;
+ if ( $transaction->data_size > 500_000 ) {
+ $self->log(LOGINFO, "skip: message too large (" .
$transaction->data_size . ")" );
+ return (DECLINED);
+ };
my $username = $self->select_username( $transaction );
my $message = $self->assemble_message($transaction);
my $filtercmd = $self->get_filter_cmd( $transaction, $username );
- $self->log(LOGWARN, $filtercmd);
+ $self->log(LOGDEBUG, $filtercmd);
my $response = $self->dspam_process( $filtercmd, $message );
if ( ! $response ) {
- $self->log(LOGWARN, "No response received from dspam. Check your logs
for errors.");
+ $self->log(LOGWARN, "skip: no response from dspam. Check logs for
errors.");
return (DECLINED);
};
- $self->log(LOGWARN, $response);
# X-DSPAM-Result: u...@example.com; result="Spam"; class="Spam";
probability=1.0000; confidence=1.00; signature=N/A
# X-DSPAM-Result: smtpd; result="Innocent"; class="Innocent";
probability=0.0023; confidence=1.00; signature=4f8dae6a446008399211546
my ($result,$prob,$conf,$sig) = $response =~
/result=\"(Spam|Innocent)\";.*?probability=([\d\.]+); confidence=([\d\.]+);
signature=(.*)/;
my $header_str = "$result, probability=$prob, confidence=$conf";
- $self->log(LOGWARN, $header_str);
- $transaction->header->add('X-DSPAM-Result', $header_str, 0);
+ $self->log(LOGDEBUG, $header_str);
+ $transaction->header->replace('X-DSPAM-Result', $header_str, 0);
- # the signature header is required if you intend to train dspam later
- # you must set Preference "signatureLocation=headers" in dspam.conf
+ # the signature header is required if you intend to train dspam later.
+ # In dspam.conf, set: Preference "signatureLocation=headers"
$transaction->header->add('X-DSPAM-Signature', $sig, 0);
return (DECLINED);
@@ -228,23 +248,24 @@ sub dspam_process {
#return $self->dspam_process_open2( $filtercmd, $message );
my ($in_fh, $out_fh);
- if (! open($in_fh, "-|")) {
+ if (! open($in_fh, '-|')) {
open($out_fh, "|$filtercmd") or die "Can't run $filtercmd: $!\n";
print $out_fh $message;
close $out_fh;
exit(0);
};
- my $response = join('', <$in_fh>);
+ #my $response = join('', <$in_fh>);
+ my $response = <$in_fh>;
close $in_fh;
chomp $response;
-
+ $self->log(LOGDEBUG, $response);
return $response;
};
sub dspam_process_open2 {
my ( $self, $filtercmd, $message ) = @_;
-# not sure why, but this is not as reliable as I'd like. What's a dspam
+# not sure why, but this is not as reliable as I'd like. What's a dspam
# error -5 mean anyway?
use FileHandle;
use IPC::Open2;
@@ -252,37 +273,107 @@ sub dspam_process_open2 {
my $pid = open2($dspam_out, $dspam_in, $filtercmd);
print $dspam_in $message;
close $dspam_in;
- my $response = join('', <$dspam_out>);
+ #my $response = join('', <$dspam_out>); # get full response
+ my $response = <$dspam_out>; # get first line only
waitpid $pid, 0;
chomp $response;
+ $self->log(LOGDEBUG, $response);
return $response;
};
sub dspam_reject {
my ($self, $transaction) = @_;
- return (DECLINED) if ! $self->{_args}->{reject};
+ my $d = $self->get_dspam_results( $transaction ) or return;
- my $status = $transaction->header->get('X-DSPAM-Result') or do {
- $self->log(LOGWARN, "dspam_reject: failed to find the dspam header");
- return (DECLINED);
+ if ( ! $d->{class} ) {
+ $self->log(LOGWARN, "skip: no dspam class detected");
+ return DECLINED;
};
- my ($clas,$probability,$confidence) = $status =~ m/^(Spam|Innocent),
probability=([\d\.]+), confidence=([\d\.]+)/i;
- $self->log(LOGDEBUG, "dspam $clas, prob: $probability, conf: $confidence");
+ my $status = "$d->{class}, $d->{confidence} c.";
+ my $reject = $self->{_args}{reject} or do {
+ $self->log(LOGINFO, "skip: reject disabled ($status)");
+ return DECLINED;
+ };
- if ( $clas eq 'Spam' && $probability == 1 && $confidence == 1 ) {
-# default of media_unsupported is DENY, so just change the message
- if ( $self->qp->connection->relay_client ) {
- $self->log(LOGWARN, "allowing spam since user authenticated");
- return DECLINED;
- };
- return Qpsmtpd::DSN->media_unsupported('dspam says, no spam please');
+ if ( $reject eq 'agree' ) {
+ return $self->dspam_reject_agree( $transaction, $d );
+ };
+ if ( $d->{class} eq 'Innocent' ) {
+ $self->log(LOGINFO, "pass: $status");
+ return DECLINED;
+ };
+ if ( $self->qp->connection->relay_client ) {
+ $self->log(LOGINFO, "skip: allowing spam, user authenticated
($status)");
+ return DECLINED;
+ };
+ if ( $d->{probability} <= $reject ) {
+ $self->log(LOGINFO, "pass, $d->{class} probability is too low
($d->{probability} < $reject)");
+ return DECLINED;
+ };
+ if ( $d->{confidence} != 1 ) {
+ $self->log(LOGINFO, "pass: $d->{class} confidence is too low
($d->{confidence})");
+ return DECLINED;
};
- return DECLINED;
+ # dspam is more than $reject percent sure this message is spam
+ $self->log(LOGINFO, "fail: $d->{class}, ($d->{confidence} confident)");
+ my $deny = $self->{_args}{reject_type} eq 'temp' ? DENYSOFT : DENY;
+ return Qpsmtpd::DSN->media_unsupported($deny,'dspam says, no spam please');
}
+sub dspam_reject_agree {
+ my ($self, $transaction, $d ) = @_;
+
+ my $sa = $transaction->notes('spamassassin' );
+
+ my $status = "$d->{class}, $d->{confidence} c";
+
+ if ( ! $sa->{is_spam} ) {
+ $self->log(LOGINFO, "pass: cannot agree, SA results missing
($status)");
+ return DECLINED;
+ };
+
+ if ( $d->{class} eq 'Spam' && $sa->{is_spam} eq 'Yes' ) {
+ $self->log(LOGINFO, "fail: agree, $status");
+ return Qpsmtpd::DSN->media_unsupported(DENY,'we agree, no spam
please');
+ };
+
+ $self->log(LOGINFO, "pass: agree, $status");
+ return DECLINED;
+};
+
+sub get_dspam_results {
+ my ( $self, $transaction ) = @_;
+
+ if ( $transaction->notes('dspam') ) {
+ return $transaction->notes('dspam');
+ };
+
+ my $string = $transaction->header->get('X-DSPAM-Result') or do {
+ $self->log(LOGWARN, "get_dspam_results: failed to find the header");
+ return;
+ };
+
+ my @bits = split(/,\s+/, $string); chomp @bits;
+ my $class = shift @bits;
+ my %d;
+ foreach (@bits) {
+ my ($key,$val) = split(/=/, $_);
+ $d{$key} = $val;
+ };
+ $d{class} = $class;
+
+ my $message = $d{class};
+ if ( defined $d{probability} && defined $d{confidence} ) {
+ $message .= ", prob: $d{probability}, conf: $d{confidence}";
+ };
+ $self->log(LOGDEBUG, $message);
+ $transaction->notes('dspam', \%d);
+ return \%d;
+};
+
sub get_filter_cmd {
my ($self, $transaction, $user) = @_;
@@ -291,51 +382,23 @@ sub get_filter_cmd {
my $min_score = $self->{_args}->{learn_from_sa} or return $default;
#$self->log(LOGDEBUG, "attempting to learn from SA");
- my $sa_status = $transaction->header->get('X-Spam-Status');
- if ( ! $sa_status ) {
- $self->log(LOGERROR, "dspam learn_from_sa was set but no X-Spam-Status
header detected");
- return $default;
- };
- chomp $sa_status;
+ my $sa = $transaction->notes('spamassassin' );
+ return $default if ! $sa || ! $sa->{is_spam};
- my ($is_spam,$score,$autolearn) = $sa_status =~ /^(yes|no),
score=([\d\.\-]+)\s.*?autolearn=([\w]+)/i;
- $self->log(LOGINFO, "sa_status: $sa_status; $is_spam; $autolearn");
-
- $is_spam = lc($is_spam);
- $autolearn = lc($autolearn);
-
- if ( $is_spam eq 'yes' && $score < $min_score ) {
- $self->log(LOGWARN, "SA spam score of $score is less than $min_score,
skipping autolearn");
+ if ( $sa->{is_spam} eq 'Yes' && $sa->{score} < $min_score ) {
+ $self->log(LOGNOTICE, "SA score $sa->{score} < $min_score, skip
autolearn");
return $default;
};
- if ( $is_spam eq 'yes' && $autolearn eq 'spam' ) {
+ if ( $sa->{is_spam} eq 'Yes' && $sa->{autolearn} eq 'spam' ) {
return "$dspam_bin --user $user --mode=tum --source=corpus --class=spam
--deliver=summary --stdout";
}
- elsif ( $is_spam eq 'no' && $autolearn eq 'ham' ) {
+ elsif ( $sa->{is_spam} eq 'No' && $sa->{autolearn} eq 'ham' ) {
return "$dspam_bin --user $user --mode=tum --source=corpus
--class=innocent --deliver=summary --stdout";
};
return $default;
};
-sub _cleanup_spam_header {
- my ($self, $transaction, $header_name) = @_;
-
- my $action = 'rename';
- if ( $self->{_args}->{leave_old_headers} ) {
- $action = lc($self->{_args}->{leave_old_headers});
- };
-
- return unless $action eq 'drop' || $action eq 'rename';
-
- my $old_header_name = $header_name;
- $old_header_name = ($old_header_name =~ s/^X-//) ?
"X-Old-$old_header_name" : "Old-$old_header_name";
-
- for my $header ( $transaction->header->get($header_name) ) {
- $transaction->header->add($old_header_name, $header) if $action eq
'rename';
- $transaction->header->delete($header_name);
- }
-}
diff --git a/t/plugin_tests/dspam b/t/plugin_tests/dspam
new file mode 100644
index 0000000..aafab8a
--- /dev/null
+++ b/t/plugin_tests/dspam
@@ -0,0 +1,97 @@
+#!perl -w
+
+use strict;
+use warnings;
+
+use Mail::Header;
+use Qpsmtpd::Constants;
+
+my $r;
+
+sub register_tests {
+ my $self = shift;
+
+ $self->register_test('test_get_filter_cmd', 2);
+ $self->register_test('test_get_dspam_results', 6);
+ $self->register_test('test_dspam_reject', 6);
+}
+
+sub test_dspam_reject {
+ my $self = shift;
+
+ my $transaction = $self->qp->transaction;
+
+ # reject not set
+ $transaction->notes('dspam', { class=> 'Spam', probability => .99,
confidence=>1 } );
+ ($r) = $self->dspam_reject( $transaction );
+ cmp_ok( $r, '==', DECLINED, "dspam_reject ($r)");
+
+ # reject exceeded
+ $self->{_args}->{reject} = .95;
+ $transaction->notes('dspam', { class=> 'Spam', probability => .99,
confidence=>1 } );
+ ($r) = $self->dspam_reject( $transaction );
+ cmp_ok( $r, '==', DENY, "dspam_reject ($r)");
+
+ # below reject threshold
+ $transaction->notes('dspam', { class=> 'Spam', probability => .94,
confidence=>1 } );
+ ($r) = $self->dspam_reject( $transaction );
+ cmp_ok( $r, '==', DECLINED, "dspam_reject ($r)");
+
+ # requires agreement
+ $self->{_args}->{reject} = 'agree';
+ $transaction->notes('spamassassin', { is_spam => 'Yes' } );
+ $transaction->notes('dspam', { class=> 'Spam', probability => .90,
confidence=>1 } );
+ ($r) = $self->dspam_reject( $transaction );
+ cmp_ok( $r, '==', DENY, "dspam_reject ($r)");
+
+ # requires agreement
+ $transaction->notes('spamassassin', { is_spam => 'No' } );
+ $transaction->notes('dspam', { class=> 'Spam', probability => .96,
confidence=>1 } );
+ ($r) = $self->dspam_reject( $transaction );
+ cmp_ok( $r, '==', DECLINED, "dspam_reject ($r)");
+
+ # requires agreement
+ $transaction->notes('spamassassin', { is_spam => 'Yes' } );
+ $transaction->notes('dspam', { class=> 'Innocent', probability => .96,
confidence=>1 } );
+ ($r) = $self->dspam_reject( $transaction );
+ cmp_ok( $r, '==', DECLINED, "dspam_reject ($r)");
+};
+
+sub test_get_dspam_results {
+ my $self = shift;
+
+ my $transaction = $self->qp->transaction;
+ my $header = Mail::Header->new(Modify => 0, MailFrom => "COERCE");
+ $transaction->header( $header );
+
+ my @dspam_sample_headers = (
+ 'Innocent, probability=0.0000, confidence=0.69',
+ 'Innocent, probability=0.0000, confidence=0.85',
+ 'Innocent, probability=0.0023, confidence=1.00',
+ 'Spam, probability=1.0000, confidence=0.87',
+ 'Spam, probability=1.0000, confidence=0.99',
+ 'Whitelisted',
+ );
+
+ foreach my $header ( @dspam_sample_headers ) {
+ $transaction->header->delete('X-DSPAM-Result');
+ $transaction->header->add('X-DSPAM-Result', $header);
+ my $r = $self->get_dspam_results($transaction);
+ ok( ref $r, "get_dspam_results ($header)" );
+ #warn Data::Dumper::Dumper($r);
+ };
+};
+
+sub test_get_filter_cmd {
+ my $self = shift;
+
+ my $transaction = $self->qp->transaction;
+ my $dspam = "/usr/local/bin/dspam";
+ $self->{_args}{dspam_bin} = $dspam;
+
+ foreach my $user ( qw/ smtpd m...@example.com / ) {
+ my $answer = "$dspam --user smtpd --mode=tum --process
--deliver=summary --stdout";
+ my $r = $self->get_filter_cmd($transaction, 'smtpd');
+ cmp_ok( $r, 'eq', $answer, "get_filter_cmd $user" );
+ };
+};
--
1.7.9.6
