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#!perl -w
=head1 NAME
noop_counter - disconnect after too many consecutive NOOPs, example plugin for the hook_noop()
=head1 DESCRIPTION
The B<noop_counter> counts the number of consecutive C<NOOP> commands given
by a client and disconnects after a given number.
Any other command than a C<NOOP> resets the counter.
One argument may be given: the number of C<NOOP>s after which the client will
be disconnected.
=head1 NOTE
This plugin should be loaded early to be able to reset the counter on any other
command.
=cut
sub register {
my ($self, $qp, @args) = @_;
$self->{_noop_count} = 0;
$self->{_max_noop} = 3;
if ($args[0] && $args[0] =~ /^\d+$/) {
$self->{_max_noop} = shift @args;
}
}
sub hook_noop {
my ($self, $transaction, @args) = @_;
++$self->{_noop_count};
### the following block is not used, RFC 2821 says we SHOULD ignore
### any arguments... so we MAY return an error if we want to :-)
# return (DENY, "Syntax error, NOOP does not take any arguments")
# if $args[0];
if ($self->{_noop_count} >= $self->{_max_noop}) {
return (DENY_DISCONNECT,
"Stop wasting my time, too many consecutive NOOPs");
}
return (DECLINED);
}
sub reset_noop_counter {
$_[0]->{_noop_count} = 0;
return (DECLINED);
}
# and bind the counter reset to the hooks, QUIT not useful here:
*hook_helo = *hook_ehlo = # HELO / EHLO
*hook_mail = # MAIL FROM:
*hook_rcpt = # RCPT TO:
*hook_data = # DATA
*hook_reset_transaction = # RSET
*hook_vrfy = # VRFY
*hook_help = # HELP
\&reset_noop_counter;
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