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Incorporate suggestions and part of a patch from Mark Powell:

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- Make the awkward silence at connection configurable (default still 1sec)
- Add an option to defer reaction to the HELO to the MAIL-FROM command
  instead, anticipating broken SMTP agents that don't gracefully handle
  disconnection after greeting.

Also made the specific response configurable (soft, hard, nothing).


git-svn-id: https://svn.perl.org/qpsmtpd/trunk@284 958fd67b-6ff1-0310-b445-bb7760255be9
This commit is contained in:
Devin Carraway 2004-08-01 07:08:07 +00:00
parent 15c90f04fa
commit b48ae7c630
1 changed files with 76 additions and 15 deletions
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91
plugins/check_earlytalker
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@ -4,28 +4,68 @@ check_earlytalker - Check that the client doesn't talk before we send the SMTP b
=head1 DESCRIPTION
Hooks connect, checks to see if the remote host starts talking before
we've issued a 2xx greeting. If so, we're likely looking at a
direct-to-MX spam agent which pipelines its entire SMTP conversation,
and will happily dump an entire spam into our mail log even if later
tests deny acceptance.
Checks to see if the remote host starts talking before we've issued a 2xx
greeting. If so, we're likely looking at a direct-to-MX spam agent which
pipelines its entire SMTP conversation, and will happily dump an entire spam
into our mail log even if later tests deny acceptance.
Such clients gets a 450 error code.
Depending on configuration, clients which behave in this way are either
immediately disconnected with a deny or denysoft code, or else are issued this
on all mail/rcpt commands in the transaction.
=head1 TODO
=head1 CONFIGURATION
Make how long we wait before reading from the socket configurable
(currently 1 second)
=over 4
Make the soft/hard response code configurable (currently DENYSOFT)
=item wait [integer]
The number of seconds to delay the initial greeting to see if the connecting
host speaks first. The default is 1.
=item action [string: deny, denysoft, log]
What to do when matching an early-talker -- the options are I<deny>,
I<denysoft> or I<log>.
If I<log> is specified, the connection will be allowed to proceed as normal,
and only a warning will be logged.
The default is I<denysoft>.
=item defer-reject [boolean]
When an early-talker is detected, if this option is set to a true value, the
SMTP greeting will be issued as usual, but all RCPT/MAIL commands will be
issued a deny or denysoft (depending on the value of I<action>). The default
is to react at the SMTP greeting stage by issuing the apropriate response code
and terminating the SMTP connection.
=back
=cut
use IO::Select;
use warnings;
use strict;
sub register {
my ($self, $qp) = @_;
my ($self, $qp, @args) = @_;
if (@args % 2) {
$self->log(LOGERROR, "Unrecognized/mismatched arguments");
return undef;
}
$self->{_args} = {
'wait' => 1,
'action' => 'denysoft',
'defer-reject' => 0,
@args,
};
$self->register_hook('connect', 'connect_handler');
$self->register_hook('mail', 'mail_handler')
if $self->{_args}->{'defer-reject'};
1;
}
sub connect_handler {
@ -33,10 +73,31 @@ sub connect_handler {
my $in = new IO::Select;
$in->add(\*STDIN) || return DECLINED;
if ($in->can_read(1)) {
$self->log(LOGDEBUG, "remote host started talking before we said hello");
return (DENYSOFT, "Don't be rude and talk before I say hello!");
if ($in->can_read($self->{_args}->{'wait'})) {
$self->log(LOGNOTICE, 'remote host started talking before we said hello');
if ($self->{_args}->{'defer-reject'}) {
$self->qp->connection->notes('earlytalker', 1);
} else {
my $msg = 'Connecting host started transmitting before SMTP greeting';
return (DENY,$msg) if $self->{_args}->{'action'} eq 'deny';
return (DENYSOFT,$msg) if $self->{_args}->{'action'} eq 'denysoft';
}
} else {
$self->log(LOGINFO, 'remote host said nothing spontaneous, proceeding');
}
$self->log(LOGINFO,"remote host said nothing spontaneous, proceeding");
return DECLINED;
}
sub mail_handler {
my ($self, $txn) = @_;
my $msg = 'Connecting host started transmitting before SMTP greeting';
return DECLINED unless $self->qp->connection->notes('earlytalker');
return (DENY,$msg) if $self->{_args}->{'action'} eq 'deny';
return (DENYSOFT,$msg) if $self->{_args}->{'action'} eq 'denysoft';
return DECLINED;
}
1;