<?
///////////////////////////////////////////////////////////////////////////
//
//    DNSBL - Spam IP address checker.
//    Copyright (C) 2011 Alexey A.Znayev
//
//    This program is free software: you can redistribute it and/or modify
//    it under the terms of the GNU General Public License as published by
//    the Free Software Foundation, either version 3 of the License, or
//    (at your option) any later version.
//
//    This program is distributed in the hope that it will be useful,
//    but WITHOUT ANY WARRANTY; without even the implied warranty of
//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//    GNU General Public License for more details.
//
//    You should have received a copy of the GNU General Public License
//    along with this program.  If not, see <http://www.gnu.org/licenses/>.
//
//    Alexey A.Znayev, znaeff@mail.ru, http://xbsoft.org, http://xbsoft.ru
//
///////////////////////////////////////////////////////////////////////////

// This file contains public class DNSBL

// This class performs IP address check in spam blocking lists as described
// on http://ru.wikipedia.org/wiki/RBL

class DNSBL {

    private $_aCheckers = array(	// list of checkers available for individual checking
	    'spamhaus' 	=> array('.zen.spamhaus.org', true), 	//available for group checking with 'all' key
	    'spamcop' 	=> array('.bl.spamcop.net',   true),	//available for group checking with 'all' key
	    'dsbl' 	=> array('.list.dsbl.org',    false),	//not available for group checking with 'all' key
	    'ordb' 	=> array('.relays.ordb.org',  false),	//not available for group checking with 'all' key
	    'sorbs' 	=> array('.dnsbl.sorbs.net',  false),	//not available for group checking with 'all' key
	    'njabl' 	=> array('.dnsbl.njabl.org',  false)	//not available for group checking with 'all' key
    ); // AZ - 1. Key 'all' is illegal
       // AZ - 2. Most of spammer IP addresses is covered by 'spamhaus' & 'spamcop' (and they are fast),
       //         some of the rest may not work sometimes, you can make them group checking available after individual testing
    
    private $_sDefaultChecker = 'spamhaus';

///////////////////////////////////////////////////////////////////////////
// CheckSpamIP - check IP for spam in checkers : given, default or all available for group checking (may be slow)
// parameters:
// string $ip - ip address
// string $checker - checker name or 'all' or nothing
// returns:
// true when IP exitsts in spam-lists of $checker or at least one of all checkers
// false when not or when ip address is local or not correct
    public function CheckSpamIP($ip, $checker = ''){
	if(empty($ip)) return false;
	if(preg_match('/^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$/', $ip) != 1) return false;
	$octets = explode('.', $ip);
	if($octets[0] == '127') return false;
	if($octets[0] == '10') return false;
	if($octets[0] == '192' && $octets[0] == '168') return false;
	if($octets[0] == '169' && $octets[0] == '254') return false;	// ms windows
	if((int)$octets[0] > 255 || (int)$octets[1] > 255 || (int)$octets[2] > 255 || (int)$octets[3] > 255 ) return false;
	$ret_val = false;
	$PTR = implode(array_reverse($octets), '.');
	if($checker === 'all'){
	    foreach(array_values($this->_aCheckers) as $c){
		if($c[1]){
		    $ret_val = $ret_val || $this->_CheckDNSAnswer(dns_get_record($PTR . $c[0], DNS_A));
		}
		if($ret_val) break;
	    }
	}else if(array_key_exists($checker, $this->_aCheckers)){
    	    $ret_val = $this->_CheckDNSAnswer(dns_get_record($PTR . $this->_aCheckers[$checker][0], DNS_A));
	}else{
    	    $ret_val = $this->_CheckDNSAnswer(dns_get_record($PTR . $this->_aCheckers[$this->_sDefaultChecker][0], DNS_A));
	}
	return $ret_val;
    }

///////////////////////////////////////////////////////////////////////////
// GetCheckers - gets list of available checker names
// returns:
// array of strings
    public function GetCheckers(){
	return array_keys($this->_aCheckers);
    }        

///////////////////////////////////////////////////////////////////////////
// GetGroupCheckers - gets list of checker names available for group checking with 'all' key
// returns:
// array of strings
    public function GetGroupCheckers(){
	$ret_val = array();
	foreach(array_keys($this->_aCheckers) as $k) if($this->_aCheckers[$k][1]) array_push($ret_val, $k);
	return $ret_val;
    }        

///////////////////////////////////////////////////////////////////////////
// GetDefaultChecker - gets default checker name
// returns:
// string
    public function GetDefaultChecker(){
	return $this->_sDefaultChecker;
    }

///////////////////////////////////////////////////////////////////////////
// SetDefaultChecker - sets default checker name
// parameters:
// string $new_checker - new default checker name
// returns:
// true when success
// false when failed ($new_checker is not in the list of available checker names)
    public function SetDefaultChecker($new_checker){
	if(array_key_exists($new_checker, $this->_aCheckers)){
	    $this->_sDefaultChecker = $new_checker;
	    return true;
	}else{
	    return false;
	}
    }

///////////////////////////////////////////////////////////////////////////
// EnableGroupChecking - sets checker available for group checking
// parameters:
// string $checker - checker name
// returns:
// true when success ($checker is included)
// false when failed ($checker is not in the list of available checker names)
    public function EnableGroupChecking($checker){
	if(array_key_exists($checker, $this->_aCheckers)){
	    $this->_aCheckers[$checker][1] = true;
	    return true;
	}else{
	    return false;
	}
    }

///////////////////////////////////////////////////////////////////////////
// DisableGroupChecking - sets checker not available for group checking
// parameters:
// string $checker - checker name
// returns:
// true when success ($checker is excluded)
// false when failed ($checker is not in the list of available checker names)
    public function DisableGroupChecking($checker){
	if(array_key_exists($checker, $this->_aCheckers)){
	    $this->_aCheckers[$checker][1] = false;
	    return true;
	}else{
	    return false;
	}
    }

// private methods

///////////////////////////////////////////////////////////////////////////
// _CheckDNSAnswer - checks DNS-server answer for 127.0.0.* values
// returns:
// true when success
// false when failed
    private function _CheckDNSAnswer($dns_answer){
	if(!is_array($dns_answer)) return false;
	$len = count($dns_answer);
	if($len <= 0) return false;
	for($i=0; $i<$len; $i++){
	    $obj = $dns_answer[$i];
	    if(!(is_object($obj) || is_array($obj))) return false;
	    $ip_str = $obj['ip'];
	    if(!is_string($ip_str)) return false;
	    $pos = strpos($ip_str, '127.0.0.');
	    if($pos !== false) return true;
	}
	return false;
    }        

} // end of class DNSBL

?>
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	<title>online &#8211; Christian Aurich</title>
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	<link>http://c-aurich.de/wordpress</link>
	<description>all about my personal interests</description>
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		<title>AI online class</title>
		<link>http://c-aurich.de/wordpress/2011/09/ai-online-class/</link>
		<comments>http://c-aurich.de/wordpress/2011/09/ai-online-class/#respond</comments>
		<pubDate>Mon, 12 Sep 2011 09:39:01 +0000</pubDate>
		<dc:creator><![CDATA[Christian]]></dc:creator>
				<category><![CDATA[internet]]></category>
		<category><![CDATA[AI]]></category>
		<category><![CDATA[online]]></category>
		<category><![CDATA[university]]></category>

		<guid isPermaLink="false">http://c-aurich.de/wordpress/?p=331</guid>
		<description><![CDATA[I just read about an online course at stanford university in the last couple of days. This is meant to be a full university course called introduction to Artificial Intelligence and includes homework assignments each week as well as midterm end final exams (only for the advanced track, basic track only requires watching the lecture &#8230; <p class="link-more"><a href="http://c-aurich.de/wordpress/2011/09/ai-online-class/" class="more-link">Continue reading<span class="screen-reader-text"> "AI online class"</span></a></p>]]></description>
				<content:encoded><![CDATA[<p>I just read about an online course at stanford university in the last couple of days. This is meant to be a full university course called <a href="http://www.ai-class.com/" target="_blank">introduction to Artificial Intelligence</a> and includes homework assignments each week as well as midterm end final exams (only for the advanced track, basic track only requires watching the lecture material). You will get a statement of accomplishment at the end.</p>
<p>I will try to take this class, lets see if I can manage to finish the advanced track.</p>
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