#!/usr/bin/perl
# by PJ
#
# Version:  1.2   7-09-01
# Version:  1.1   2-15-01
# Version:  1.0   2-13-01
#
# Purpose:  To check incoming emails for same to address as from address.
#		This should help reduce spam to your mail box.
#		Place the file location in your .qmail file before any other options.
#		ie    |/var/qmail/bin/check_to_from.pl
#		      ./Maildir/
#
# Bugs:  E-mail (dysan at dysan dot net) with any bug information or ideas.
#        (replace words with symbols for email)

#--Variables--#
 $log = "1";      		#-  0 eq off, 1 eq on.
 $log_file = "spam/spam.log";	#-  your log file name and location.
 $email_file = "spam/email.log"; #- saved email.
 $rcpt = "/var/qmail/control/rcpthosts";	#-qmail's rcpthosts file 
 $message = "Sorry this e-mail address does not exist. (#5.1.1)\nPlease remove this e-mail address from your list.";	#-return error message

 $debug = "0";	#- 0 = off; 1 = on.


#- (( Do Not edit the below info )) -#
#-Get the date for logging.
 ($minute,$hour,$day,$month,$year) = (localtime) [1,2,3,4,5];
   $month += "1";
   $year += "1900";
   if($month <= "9") { $month = "0" . "$month"; }
   if($minute <= "9") { $minute = "0" . "$minute"; }
   $date = "$month/$day/$year - $hour:$minute";


#-print exit codes.
if($debug == "1") {  print "Exit code 0 = success.\nExit code 99 = success and abort .qmail.\nExit code 100 = bounce(return) email.\n";  } 

#-Read in the email message and go through each line.
 while(<>) {
	push (@HEADER, $_);

	#- find the to and from addresses.
	 chomp();
	 $_ =~ tr/[A-Z]/[a-z]/;

	#-look for the to email address.
	 if(!$to) {
	   if(/^to: .*\b(\S+\@[\w\.]+)\b/) {
	     $to = $1;
	     lc($to);
	     if($debug == "1") {  print "To address: $to\n";  }
	   }
	 }

	#-look for the from email address.
	 if(!$from) {
	   if(/^from: .*\b(\S+\@[\w\.]+)\b/) {
	     $from = $1;
	     lc($from);
	     if($debug == "1") {  print "From address: $from\n";  }
	   }
	 }
}

#-check against specific e-mail addresses.
 if ($to =~ "daemon" || $from =~ "daemon") {
   if($debug == "1") {  print "Email for mailer-daemon and exited with code 99.\n";  }
   exit 99;
 }

#-if from a trusted host in rcpthosts file then except.
 open(RC,"$rcpt") || die "Can not open $rcpt: $!";
   while (<RC>) {
     chomp;
     if ($from =~ $_) { 
	if($debug == "1") {  print "Domain found in $rcpt file and exited with code 0.\n";  }
	exit 0;
     }
   }
 close(RC);


#-error if no from or to address are in email.
 &logger("$message", "No 'from' e-mail address found.", "<$from>") unless $from; 
 &logger("$message", "No 'to' e-mail address found.", "<$from>") unless $to; 


#-error if to and from addresses match.
 if ($to eq $from) {
    if($debug == "1") {  print "To and From addresses matched.\n";  }
    &logger("$message", "To & From e-mail addresses matched.", "<$from>");
 }

#-print debug if finished script.
 if($debug == "1") { print "Good email!\n"; }

sub logger($) {
	#- log email address.

	#-log event.
	if($log == "1") {
	  open(LOG,">>$log_file") || die "Can not open $log_file: $!";
	    print LOG "$date||From\:$_[2]||$_[1]\n";
	  close(LOG);
	  if($debug == "1") {  print "Wrote to $log_file file.\n";  }
	}

	#-save copy of email.
	if($log == "1") {
	  open(EM,">>$email_file") || die "Can not open $email_file: $!";
	    print EM "\n-----[Start of E-mail  $date]---------------------------------\n";
	    foreach $ln (@HEADER) {
	      chomp($ln);
	      print EM "$ln\n";
	    }
	    print EM "-----[End of E-mail]------------------------------------------\n";
	  close(EM);
	  if($debug == "1") {  print "Wrote to $email_file file.\n";  }
	}

	#-send error message back to sender.
	warn "$_[0]\n";
	if($debug == "1") {  print "Bounced email and exited with code 100.\n";  }
	exit 100;
}