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//:Emailfiltering on your output - output filtering with the options below - Mailto links can be encrypted by a Javascript
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//:usage:  [[EmailFilter]] 
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// You can configure the output filtering with the options below.
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// Tip: Mailto links can be encrypted by a Javascript function. 
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// To make use of this option, one needs to add the PHP code 
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//       register_frontend_modfiles('js');
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// into the <head> section of the index.php of your template. 
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// Without this modification, only the @ character in the mailto part will be replaced.
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// Basic Email Configuration: 
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// Filter Email addresses in text 0 = no, 1 = yes - default 1
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$filter_settings['email_filter'] = '1';
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// Filter Email addresses in mailto links 0 = no, 1 = yes - default 1
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$filter_settings['mailto_filter'] = '1';
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// Email Replacements, replace the '@' and the '.' by default (at) and (dot)
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$filter_settings['at_replacement']  = '(at)';
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$filter_settings['dot_replacement'] = '(dot)';
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// No need to change stuff underneatch unless you know what you are doing.
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// work out the defined output filter mode: possible output filter modes: [0], 1, 2, 3, 6, 7
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// 2^0 * (0.. disable, 1.. enable) filtering of mail addresses in text
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// 2^1 * (0.. disable, 1.. enable) filtering of mail addresses in mailto links
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// 2^2 * (0.. disable, 1.. enable) Javascript mailto encryption (only if mailto filtering enabled)
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// only filter output if we are supposed to
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if($filter_settings['email_filter'] != '1' && $filter_settings['mailto_filter'] != '1'){
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	// nothing to do ...
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	return true;
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}
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// check if non mailto mail addresses needs to be filtered
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$output_filter_mode = ($filter_settings['email_filter'] == '1') ? 1 : 0;		// 0|1
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// check if mailto mail addresses needs to be filtered
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if($filter_settings['mailto_filter'] == '1') {
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	$output_filter_mode = $output_filter_mode + 2;								// 0|2
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	// check if Javascript mailto encryption is enabled (call register_frontend_functions in the template)
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	$search = '<script src="' .WB_URL .'/modules/droplets/js/mdcr.js" type="text/javascript"></script>';
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	if(strpos($wb_page_data, $search) !== false) { 
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		$output_filter_mode = $output_filter_mode + 4;							// 0|4
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	}
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}
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// define some constants so we do not call the database in the callback function again
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define('OUTPUT_FILTER_MODE', (int) $output_filter_mode);
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define('OUTPUT_FILTER_AT_REPLACEMENT', $filter_settings['at_replacement']);
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define('OUTPUT_FILTER_DOT_REPLACEMENT', $filter_settings['dot_replacement']);
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// function to filter mail addresses embedded in text or mailto links before outputing them on the frontend
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if (!function_exists('filter_mail_addresses')) {
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	function filter_mail_addresses($match) { 
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	// check if required output filter mode is defined
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		if(!(defined('OUTPUT_FILTER_MODE') && defined('OUTPUT_FILTER_MODE') && defined('OUTPUT_FILTER_MODE'))) {
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			return $match[0];
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		}
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		$search = array('@', '.');
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		$replace = array(OUTPUT_FILTER_AT_REPLACEMENT ,OUTPUT_FILTER_DOT_REPLACEMENT);
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		// check if the match contains the expected number of subpatterns (6|8)
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		if(count($match) == 8) {
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			/**
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				OUTPUT FILTER FOR EMAIL ADDRESSES EMBEDDED IN TEXT
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			**/
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			// 1.. text mails only, 3.. text mails + mailto (no JS), 7 text mails + mailto (JS)
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			if(!in_array(OUTPUT_FILTER_MODE, array(1,3,7))) return $match[0];
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			// do not filter mail addresses included in input tags (<input ... value = "test@mail)
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			if (strpos($match[6], 'value') !== false) return $match[0];
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			// filtering of non mailto email addresses enabled
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			return str_replace($search, $replace, $match[0]);
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		} elseif(count($match) == 6) {
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			/**
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				OUTPUT FILTER FOR EMAIL ADDRESSES EMBEDDED IN MAILTO LINKS
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			**/
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			// 2.. mailto only (no JS), 3.. text mails + mailto (no JS), 6.. mailto only (JS), 7.. all filters active
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			if(!in_array(OUTPUT_FILTER_MODE, array(2,3,6,7))) return $match[0];
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			// check if last part of the a href link: >xxxx</a> contains a email address we need to filter
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			$pattern = '#[A-Z0-9._%+-]+@(?:[A-Z0-9-]+\.)+[A-Z]{2,4}#i';
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			if(preg_match_all($pattern, $match[5], $matches)) {
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				foreach($matches as $submatch) {
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					foreach($submatch as $value) {
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						// replace all . and all @ in email address parts by (dot) and (at) strings
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						$match[5] = str_replace($value, str_replace($search, $replace, $value), $match[5]);
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					}
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				}
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			}
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			// check if Javascript encryption routine is enabled
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			if(in_array(OUTPUT_FILTER_MODE, array(6,7))) {
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				/** USE JAVASCRIPT ENCRYPTION FOR MAILTO LINKS **/
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				// extract possible class and id attribute from ahref link
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				preg_match('/class\s*?=\s*?("|\')(.*?)\1/ix', $match[0], $class_attr);
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				$class_attr = empty($class_attr) ? '' : 'class="' . $class_attr[2] . '" ';
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				preg_match('/id\s*?=\s*?("|\')(.*?)\1/ix', $match[0], $id_attr);
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				$id_attr = empty($id_attr) ? '' : 'id="' . $id_attr[2] . '" ';
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				// preprocess mailto link parts for further usage
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				$search = array('@', '.', '_', '-'); $replace = array('F', 'Z', 'X', 'K');
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				$email_address = str_replace($search, $replace, strtolower($match[2]));
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				$email_subject = rawurlencode(html_entity_decode($match[3]));
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				// create a random encryption key for the Caesar cipher
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				mt_srand((double)microtime()*1000000);	// (PHP < 4.2.0)
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				$shift = mt_rand(1, 25);
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				// encrypt the email using an adapted Caesar cipher
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		  		$encrypted_email = "";
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				for($i = strlen($email_address) -1; $i > -1; $i--) {
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					if(preg_match('#[FZXK0-9]#', $email_address[$i], $characters)) {
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						$encrypted_email .= $email_address[$i];
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					} else {	
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						$encrypted_email .= chr((ord($email_address[$i]) -97 + $shift) % 26 + 97);
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					}
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				}
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				$encrypted_email .= chr($shift + 97);
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				// build the encrypted Javascript mailto link
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				$mailto_link  = "<a {$class_attr}{$id_attr}href=\"javascript:mdcr('$encrypted_email','$email_subject')\">" .$match[5] ."</a>";
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				return $mailto_link;	
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			} else {
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				/** DO NOT USE JAVASCRIPT ENCRYPTION FOR MAILTO LINKS **/
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				// as minimum protection, replace replace @ in the mailto part by (at)
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				// dots are not transformed as this would transform my.name@domain.com into: my(dot)name(at)domain(dot)com
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				// rebuild the mailto link from the subpatterns (at the missing characters " and </a>")
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				return $match[1] .str_replace('@', OUTPUT_FILTER_AT_REPLACEMENT, $match[2]) .$match[3] .'"' .$match[4] .$match[5] .'</a>';
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				// if you want to protect both, @ and dots, comment out the line above and remove the comment from the line below
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				// return $match[1] .str_replace($search, $replace, $match[2]) .$match[3] .'"' .$match[4] .$match[5] .'</a>';
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			}
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		}
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		// number of subpatterns do not match the requirements ... do nothing
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		return $match[0];
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	}		
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}
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// first search part to find all mailto email addresses
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$pattern = '#(<a[^<]*href\s*?=\s*?"\s*?mailto\s*?:\s*?)([A-Z0-9._%+-]+@(?:[A-Z0-9-]+\.)+[A-Z]{2,4})([^"]*?)"([^>]*>)(.*?)</a>';
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// second part to find all non mailto email addresses
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$pattern .= '|(value\s*=\s*"|\')??\b([A-Z0-9._%+-]+@(?:[A-Z0-9-]+\.)+[A-Z]{2,4})\b#i';
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// Sub 1:\b(<a.[^<]*href\s*?=\s*?"\s*?mailto\s*?:\s*?)		-->	"<a id="yyy" class="xxx" href = " mailto :" ignoring white spaces
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// Sub 2:([A-Z0-9._%+-]+@(?:[A-Z0-9-]+\.)+[A-Z]{2,4})		-->	the email address in the mailto: part of the mail link
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// Sub 3:([^"]*?)"							--> possible ?Subject&cc... stuff attached to the mail address
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// Sub 4:([^>]*>)							--> all class or id statements after the mailto but before closing ..>
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// Sub 5:(.*?)</a>\b						--> the mailto text; all characters between >xxxxx</a>
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// Sub 6:|\b([A-Z0-9._%+-]+@(?:[A-Z0-9-]+\.)+[A-Z]{2,4})\b		--> email addresses which may appear in the text (require word boundaries)
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$content = $wb_page_data;			
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// find all email addresses embedded in the content and filter them using a callback function
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$content = preg_replace_callback($pattern, 'filter_mail_addresses', $content);
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$wb_page_data = $content;
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return true;
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