From b48ae7c6303ef5333ec1cf44c336abf7b9e96acd Mon Sep 17 00:00:00 2001
From: Devin Carraway <qpsmtpd@devin.com>
Date: Sun, 1 Aug 2004 07:08:07 +0000
Subject: [PATCH] Incorporate suggestions and part of a patch from Mark Powell:
 - 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
---
 plugins/check_earlytalker | 91 ++++++++++++++++++++++++++++++++-------
 1 file changed, 76 insertions(+), 15 deletions(-)

diff --git a/plugins/check_earlytalker b/plugins/check_earlytalker
index 0f2d867..b444517 100644
--- a/plugins/check_earlytalker
+++ b/plugins/check_earlytalker
@@ -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;
+