[Spamassassin Wiki] Update of "RelayedByDialup" by CordBeermann

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The following page has been changed by CordBeermann:
http://wiki.apache.org/spamassassin/RelayedByDialup

New page:
#language en
== How it works ==

This plugin checks if a mail has been delivered directly from a dialup-IP. It simply uses the last trusted received-line for the IP and the DNS-Names and tries to find out if the IP-Number is somehow coded into the DNS.

== Requirements ==

none.

== Installation ==

Save the two files below in your local configuration directory.

== Remarks ==

 * Note that this is my first SA plugin, so any feedback is welcome
 * This Plugin 

== ToDo ==

 * Words are hardcoded. Should be a configuration parameter instead.
 * Instead of checking for specific words, it might be better to "check if the image contains a certain amount of text", since it is not very likely that people send legitimate mail with text in images.

-- Author: Maarten de Boer, mdeboer -at- iua -dot- upf -dot- edu

== Changelog ==

Version 2: 
 
 * Use {{{convert}}} instead of {{{giftopnm}}}, because I received some mails with .gif's that were actually .jpg's. {{{convert}}} handles that ok.
 * Some words added

== Code ==

=== Ocr.cf ===

{{{
loadplugin Ocr Ocr.pm
body OCR eval:check_ocr()
describe OCR Check if text in attached images contains spam words
score OCR 3.0
}}}

=== Ocr.pm ===

{{{
# Ocr plugin, version 2
package Ocr;

use strict;
use Mail::SpamAssassin;
use Mail::SpamAssassin::Util;
use Mail::SpamAssassin::Plugin;

our @ISA = qw (Mail::SpamAssassin::Plugin);

# constructor: register the eval rule
sub new {
   my ( $class, $mailsa ) = @_;
   $class = ref($class) || $class;
   my $self = $class->SUPER::new($mailsa);
   bless( $self, $class );
   $self->register_eval_rule("check_ocr");
   return $self;
}

sub check_ocr {
   my ( $self, $pms ) = @_;
   my $cnt = 0;
   foreach my $p ( $pms->{msg}->find_parts("image") ) {
      my ( $ctype, $boundary, $charset, $name ) =
        Mail::SpamAssassin::Util::parse_content_type(
         $p->get_header('content-type') );
      if ( $ctype eq "image/gif" ) {
         open OCR, "|/usr/bin/convert -flatten - pnm:-|/usr/bin/gocr -i - > /tmp/spamassassin.ocr.$$";
         foreach $p ( $p->decode() ) {
            print OCR $p;
         }
         close OCR;
         open OCR, "/tmp/spamassassin.ocr.$$";
         my @words =
           ( 'company', 'money', 'stock', 'million', 'thousand', 'buy', 'price', 'don\'t' );
         while (<OCR>) {
            my $w;
            foreach $w (@words) {
               if (m/$w/i) {
                  $cnt++;
               }
            }
         }
         unlink "/tmp/spamassassin.ocr.$$";
      }
   }
   return ( $cnt > 1 );
}

1;
}}}