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< ? php
/**
* eGroupWare API : egw class to include ( and configure ( basic )) htmLawed by Santosh Patnaik
*
* @ link http :// www . egroupware . org
* @ license http :// opensource . org / licenses / gpl - license . php GPL - GNU General Public License
* @ package api
* @ subpackage htmLawed
* @ author Klaus Leithoff < kl - AT - stylite . de >
* @ version $Id $
*/
require_once ( EGW_API_INC . '/htmLawed/htmLawed.php' );
/**
* This class does NOT use anything EGroupware specific , it just calls htmLawed and supports autoloading
* while matching egw namespace requirements . It also provides ( as a non class function ) a hook_tag function
* to do further tag / attribute validation
*/
class egw_htmLawed
{
/**
* config options see constructor
*
* @ var Configuration
*/
var $Configuration ;
/**
* The $spec argument can be used to disallow an otherwise legal attribute for an element ,
* or to restrict the attribute ' s values . This can also be helpful as a security measure
* ( e . g . , in certain versions of browsers , certain values can cause buffer overflows and
* denial of service attacks ), or in enforcing admin policy compliance . $spec is specified
* as a string of text containing one or more rules , with multiple rules separated from each
* other by a semi - colon (;)
*
* @ var Spec
*/
var $Spec ;
/**
* Constructor
*/
function __construct ()
{
// may hold some Standard configuration
/*
$cfg = array (
'abs_url' => array ( '3' , '0' , 'absolute/relative URL conversion' , '-1' ),
'and_mark' => array ( '2' , '0' , 'mark original <em>&</em> chars' , '0' , 'd' => 1 ), // 'd' to disable
'anti_link_spam' => array ( '1' , '0' , 'modify <em>href</em> values as an anti-link spam measure' , '0' , array ( array ( '30' , '1' , '' , 'regex for extra <em>rel</em>' ), array ( '30' , '2' , '' , 'regex for no <em>href</em>' ))),
'anti_mail_spam' => array ( '1' , '0' , 'replace <em>@</em> in <em>mailto:</em> URLs' , '0' , '8' , 'NO@SPAM' , 'replacement' ),
'balance' => array ( '2' , '1' , 'fix nestings and balance tags' , '0' ),
'base_url' => array ( '' , '' , 'base URL' , '25' ),
'cdata' => array ( '4' , 'nil' , 'allow <em>CDATA</em> sections' , 'nil' ),
'clean_ms_char' => array ( '3' , '0' , 'replace bad characters introduced by Microsoft apps. like <em>Word</em>' , '0' ),
'comment' => array ( '4' , 'nil' , 'allow HTML comments' , 'nil' ),
'css_expression' => array ( '2' , 'nil' , 'allow dynamic expressions in CSS style properties' , 'nil' ),
'deny_attribute' => array ( '1' , '0' , 'denied attributes' , '0' , '50' , '' , 'these' ),
'direct_list_nest' => array ( '2' , 'nil' , 'allow direct nesting of a list within another without requiring it to be a list item' , 'nil' ),
'elements' => array ( '' , '' , 'allowed elements' , '50' ),
'hexdec_entity' => array ( '3' , '1' , 'convert hexadecimal numeric entities to decimal ones, or vice versa' , '0' ),
'hook' => array ( '' , '' , 'name of hook function' , '25' ),
'hook_tag' => array ( '' , '' , 'name of custom function to further check attribute values' , '25' ),
'keep_bad' => array ( '7' , '6' , 'keep, or remove <em>bad</em> tag content' , '0' ),
'lc_std_val' => array ( '2' , '1' , 'lower-case std. attribute values like <em>radio</em>' , '0' ),
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'make_tag_strict' => array ( '3' , 'nil' , 'transform deprecated elements' , 'nil' ), 3 is a new own config value , to indicate that transformation is to be performed , but don ' t transform font as size transformation of numeric sizes to keywords alters the intended result too much
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'named_entity' => array ( '2' , '1' , 'allow named entities, or convert numeric ones' , '0' ),
'no_deprecated_attr' => array ( '3' , '1' , 'allow deprecated attributes, or transform them' , '0' ),
'parent' => array ( '' , 'div' , 'name of parent element' , '25' ),
'safe' => array ( '2' , '0' , 'for most <em>safe</em> HTML' , '0' ),
'schemes' => array ( '' , 'href: aim, feed, file, ftp, gopher, http, https, irc, mailto, news, nntp, sftp, ssh, telnet; *:file, http, https' , 'allowed URL protocols' , '50' ),
'show_setting' => array ( '' , 'htmLawed_setting' , 'variable name to record <em>finalized</em> htmLawed settings' , '25' , 'd' => 1 ),
'style_pass' => array ( '2' , 'nil' , 'do not look at <em>style</em> attribute values' , 'nil' ),
'tidy' => array ( '3' , '0' , 'beautify/compact' , '-1' , '8' , '1t1' , 'format' ),
'unique_ids' => array ( '2' , '1' , 'unique <em>id</em> values' , '0' , '8' , 'my_' , 'prefix' ),
'valid_xhtml' => array ( '2' , 'nil' , 'auto-set various parameters for most valid XHTML' , 'nil' ),
'xml:lang' => array ( '3' , 'nil' , 'auto-add <em>xml:lang</em> attribute' , '0' ),
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'allow_for_inline' => array ( 'table' ), //block elements allowed for nesting when only inline is allowed; Example span does not allow block elements as table; table is the only element tested so far
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);
*/
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$this -> Configuration = array ( 'comment' => 1 , //remove comments
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'make_tag_strict' => 3 , //3 is a new own config value, to indicate that transformation is to be performed, but don't transform font, as size transformation of numeric sizes to keywords alters the intended result too much
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'balance' => 0 , //turn off tag-balancing (config['balance']=>0). That will not introduce any security risk; only standards-compliant tag nesting check/filtering will be turned off (basic tag-balance will remain; i.e., there won't be any unclosed tag, etc., after filtering)
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// tidy eats away even some wanted whitespace, so we switch it off;
// we used it for its compacting and beautifying capabilities, which resulted in better html for further processing
'tidy' => 0 ,
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'elements' => " * -script " ,
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'deny_attribute' => 'on*' ,
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'schemes' => 'href: file, ftp, http, https, mailto; src: cid, data, file, ftp, http, https; *:file, http, https' ,
'hook_tag' => " hl_my_tag_transform " ,
);
$this -> Spec = 'img=alt(noneof="image"/default="")' ;
}
/**
* egw_htmlLawed
*
* @ param varchar $html2check = text input Text to check
* @ param mixed $Config = text or array
* @ param mixed $Spec = text or array ; The '$spec' argument can be used to disallow an otherwise legal attribute for an element
* @ return varchar cleaned / fixed html
*/
function egw_htmLawed ( $html2check , $Config = null , $Spec = array ())
{
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//error_log(__METHOD__.__LINE__.' Input:'.$html2check);
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if ( is_array ( $Config ) && is_array ( $this -> Configuration )) $Config = array_merge ( $this -> Configuration , $Config );
if ( empty ( $Config )) $Config = $this -> Configuration ;
if ( empty ( $Spec )) $Spec = $this -> Spec ;
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// If we are processing mails, we take out stuff in <style> stuff </style> tags and
// put it back in after purifying; styles are processed for known security risks
// in html::getStyles
$styles = '' ;
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// we allow filtered style sections now throughout egroupware
/*if ($Config['hook_tag'] =="hl_email_tag_transform")*/ $styles = html :: getStyles ( $html2check );
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//error_log(__METHOD__.__LINE__.array2string($styles));
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return ( $styles ? $styles : '' ) . htmLawed ( $html2check , $Config , $Spec );
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}
}
/**
* hl_my_tag_transform
*
* function to provide individual checks for element attribute pairs
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* implemented so far : img checking for alt attribute == image ; set this to empty
* a checking for title , replacing @
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* blockquote checking for cite , replacing @
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*/
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function hl_my_tag_transform ( $element , $attribute_array = 0 )
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{
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// If second argument is not received, it means a closing tag is being handled
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if ( is_numeric ( $attribute_array )){
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return " </ $element > " ;
}
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//if ($element=='img') error_log(__METHOD__.__LINE__." ".$element.'->'.array2string($attribute_array));
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if ( $element == 'td' && isset ( $attribute_array [ 'background' ]))
{
if ( stripos ( $attribute_array [ 'background' ], $GLOBALS [ 'egw' ] -> link ( '/index.php' )) !== false )
{
//error_log(__METHOD__.__LINE__.array2string($attribute_array));
//$attribute_array['background'] = 'url('.$attribute_array['background'].');';
}
else
{
// $attribute_array['background']='denied:'.$attribute_array['background'];
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unset ( $attribute_array [ 'background' ]); // only internal background images are allowed
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}
}
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// Elements other than 'img' or 'img' without a 'img' attribute are returned unchanged
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if ( $element == 'img' )
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{
// Re-build 'alt'
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if ( isset ( $attribute_array [ 'alt' ])) $attribute_array [ 'alt' ] = ( $attribute_array [ 'alt' ] == 'image' ? '' : $attribute_array [ 'alt' ]);
if ( isset ( $attribute_array [ 'alt' ]) && strpos ( $attribute_array [ 'alt' ], '@' ) !== false ) $attribute_array [ 'alt' ] = str_replace ( '@' , '(at)' , $attribute_array [ 'alt' ]);
}
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if ( isset ( $attribute_array [ 'title' ]))
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{
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if ( strpos ( $attribute_array [ 'title' ], '@' ) !== false ) $attribute_array [ 'title' ] = str_replace ( '@' , '(at)' , $attribute_array [ 'title' ]);
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}
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if ( isset ( $attribute_array [ 'face' ]))
{
if ( stripos ( $attribute_array [ 'face' ], 'script' ) !== false ) $attribute_array [ 'face' ] = str_ireplace ( 'script' , '' , $attribute_array [ 'face' ]);
}
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if ( $element == 'blockquote' )
{
if ( isset ( $attribute_array [ 'cite' ]))
{
if ( strpos ( $attribute_array [ 'cite' ], '@' ) !== false ) $attribute_array [ 'cite' ] = str_replace ( '@' , '(at)' , $attribute_array [ 'cite' ]);
}
}
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/*
// Elements other than 'span' or 'span' without a 'style' attribute are returned unchanged
if ( $element == 'span' && isset ( $attribute_array [ 'style' ]))
{
// Identify CSS properties and values
$css = explode ( ';' , $attribute_array [ 'style' ]);
$style = array ();
foreach ( $css as $v ){
if (( $p = strpos ( $v , ':' )) > 1 && $p < strlen ( $v )){
$css_property_name = trim ( substr ( $v , 0 , $p ));
$css_property_value = trim ( substr ( $v , $p + 1 ));
$style [] = " $css_property_name : $css_property_value " ;
}
}
// Alter the CSS property as required
// Black Arial must be at a font-size of 24
if ( isset ( $style [ 'font-family' ]) && $style [ 'font-family' ] == 'Arial' && isset ( $style [ 'color' ]) && $style [ 'color' ] == '#000000' ){
$style [ 'font-size' ] == '24' ;
}
// And so on for other criteria
// ...
// Re-build 'style'
$attribute_array [ 'style' ] = implode ( '; ' , $style );
}
*/
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if ( isset ( $attribute_array [ 'style' ]) && stripos ( $attribute_array [ 'style' ], 'script' ) !== false ) $attribute_array [ 'style' ] = str_ireplace ( 'script' , '' , $attribute_array [ 'style' ]);
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if ( $element == 'a' )
{
//error_log(__METHOD__.__LINE__.array2string($attribute_array));
// rebuild Anchors, if processed by hl_email_tag_transform
if ( strpos ( $attribute_array [ 'href' ], " denied:javascript:GoToAnchor(' " ) === 0 )
{
$attribute_array [ 'href' ] = str_ireplace ( " '); " , '' , str_ireplace ( " denied:javascript:GoToAnchor(' " , " # " , $attribute_array [ 'href' ]));
}
if ( strpos ( $attribute_array [ 'href' ], " javascript:GoToAnchor(' " ) === 0 )
{
$attribute_array [ 'href' ] = str_ireplace ( " '); " , '' , str_ireplace ( " javascript:GoToAnchor(' " , " # " , $attribute_array [ 'href' ]));
}
if ( strpos ( $attribute_array [ 'href' ], 'denied:javascript' ) === 0 ) $attribute_array [ 'href' ] = '' ;
}
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// Build the attributes string
$attributes = '' ;
foreach ( $attribute_array as $k => $v ){
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$attributes .= " { $k } = \" { $v } \" " ;
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}
// Return the opening tag with attributes
static $empty_elements = array ( 'area' => 1 , 'br' => 1 , 'col' => 1 , 'embed' => 1 , 'hr' => 1 , 'img' => 1 , 'input' => 1 , 'isindex' => 1 , 'param' => 1 );
return " < { $element } { $attributes } " . ( isset ( $empty_elements [ $element ]) ? ' /' : '' ) . '>' ;
}
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/**
* hl_email_tag_transform
*
* function to provide individual checks for element attribute pairs
* implemented so far : img - checking for alt attribute == image ; set this to empty
* - control for / on external Images and src - length
* a - checking for title and href , replacing @ accordingly
* - navigate to local anchors without reloading the page
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* blockquote - checking for cite , replacing @
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* throwing away excess div elements , that carry no style or class or id info
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*/
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function hl_email_tag_transform ( $element , $attribute_array = 0 )
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{
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//error_log(__METHOD__.__LINE__.$element.array2string($attribute_array));
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static $lastelement ;
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static $throwawaycounter ;
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if ( is_null ( $lastelement )) $lastelement = '' ;
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if ( is_null ( $throwawaycounter )) $throwawaycounter = 0 ;
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//if ($throwawaycounter>1) error_log(__METHOD__.__LINE__.' '.$throwawaycounter.$element.array2string($attribute_array));
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if ( $element == 'div' && $element == $lastelement && ( $attribute_array == 0 || empty ( $attribute_array )))
{
if ( is_array ( $attribute_array )) $throwawaycounter ++ ;
if ( $attribute_array == 0 && $throwawaycounter > 0 ) $throwawaycounter -- ;
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if ( $throwawaycounter > 1 ) return '' ;
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}
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if ( $lastelement == 'div' && $element != $lastelement && is_array ( $attribute_array )) $throwawaycounter = 0 ;
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if ( is_array ( $attribute_array ) && ! empty ( $attribute_array ) && $element == 'div' )
{
$lastelement = 'div_with_attr' ;
}
else
{
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if ( is_array ( $attribute_array )) $lastelement = $element ;
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}
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// If second argument is not received, it means a closing tag is being handled
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if ( is_numeric ( $attribute_array )){
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if ( $element == $lastelement ) $lastelement = '' ;
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return " </ $element > " ;
}
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//if ($element=='a') error_log(__METHOD__.__LINE__." ".$element.'->'.array2string($attribute_array));
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if ( $element == 'td' && isset ( $attribute_array [ 'background' ]))
{
if ( stripos ( $attribute_array [ 'background' ], 'cid:' ) !== false )
{
//error_log(__METHOD__.__LINE__.array2string($attribute_array));
//$attribute_array['background'] = 'url('.$attribute_array['background'].');';
}
else
{
// $attribute_array['background']='denied:'.$attribute_array['background'];
unset ( $attribute_array [ 'background' ]); // only cid style background images are allowed
}
}
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// Elements other than 'img' or 'img' without a 'img' attribute are returned unchanged
if ( $element == 'img' )
{
// Re-build 'alt'
if ( isset ( $attribute_array [ 'alt' ])) $attribute_array [ 'alt' ] = ( $attribute_array [ 'alt' ] == 'image' ? '' : $attribute_array [ 'alt' ]);
if ( isset ( $attribute_array [ 'alt' ]) && strpos ( $attribute_array [ 'alt' ], '@' ) !== false ) $attribute_array [ 'alt' ] = str_replace ( '@' , '(at)' , $attribute_array [ 'alt' ]);
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// $GLOBALS['egw_info']['user']['preferences']['mail']['allowExternalIMGs'] ? '' : 'match' => '/^cid:.*/'),
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if ( isset ( $attribute_array [ 'src' ]))
{
if ( ! ( strlen ( $attribute_array [ 'src' ]) > 4 && strlen ( $attribute_array [ 'src' ] < 400 )))
{
$attribute_array [ 'alt' ] = $attribute_array [ 'alt' ] . ' [blocked (reason: url length):' . $attribute_array [ 'src' ] . ']' ;
if ( ! isset ( $attribute_array [ 'title' ])) $attribute_array [ 'title' ] = $attribute_array [ 'alt' ];
$attribute_array [ 'src' ] = common :: image ( 'phpgwapi' , 'dialog_error' );
}
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if ( ! $GLOBALS [ 'egw_info' ][ 'user' ][ 'preferences' ][ 'mail' ][ 'allowExternalIMGs' ])
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{
if ( ! preg_match ( '/^cid:.*/' , $attribute_array [ 'src' ]))
{
$attribute_array [ 'alt' ] = $attribute_array [ 'alt' ] . ' [blocked external image:' . $attribute_array [ 'src' ] . ']' ;
if ( ! isset ( $attribute_array [ 'title' ])) $attribute_array [ 'title' ] = $attribute_array [ 'alt' ];
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$attribute_array [ 'src' ] = common :: image ( 'mail' , 'no-image-shown' );
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$attribute_array [ 'border' ] = 1 ;
if ( $attribute_array [ 'style' ])
{
if ( stripos ( $attribute_array [ 'style' ], 'border' ) !== false ) $attribute_array [ 'style' ] = preg_replace ( '~border(:|-left:|-right:|-bottom:|-top:)+ (0px)+ (none)+;~si' , '' , $attribute_array [ 'style' ]);
}
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}
}
}
}
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if ( isset ( $attribute_array [ 'style' ]) && stripos ( $attribute_array [ 'style' ], 'script' ) !== false ) $attribute_array [ 'style' ] = str_ireplace ( 'script' , '' , $attribute_array [ 'style' ]);
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if ( isset ( $attribute_array [ 'title' ]))
{
if ( strpos ( $attribute_array [ 'title' ], '@' ) !== false ) $attribute_array [ 'title' ] = str_replace ( '@' , '(at)' , $attribute_array [ 'title' ]);
}
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if ( $element == 'blockquote' )
{
if ( isset ( $attribute_array [ 'cite' ]))
{
if ( strpos ( $attribute_array [ 'cite' ], '@' ) !== false ) $attribute_array [ 'cite' ] = str_replace ( '@' , '(at)' , $attribute_array [ 'cite' ]);
}
}
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if ( $element == 'a' )
{
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//error_log(__METHOD__.__LINE__.array2string($attribute_array));
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if ( strpos ( $attribute_array [ 'href' ], 'denied:javascript' ) === 0 ) $attribute_array [ 'href' ] = '' ;
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if ( isset ( $attribute_array [ 'name' ]) && isset ( $attribute_array [ 'id' ])) $attribute_array [ 'id' ] = $attribute_array [ 'name' ];
if ( strpos ( $attribute_array [ 'href' ], '@' ) !== false ) $attribute_array [ 'href' ] = str_replace ( '@' , '%40' , $attribute_array [ 'href' ]);
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if ( strpos ( $attribute_array [ 'href' ], '#' ) === 0 && ( isset ( emailadmin_imapbase :: $htmLawed_config [ 'transform_anchor' ]) && emailadmin_imapbase :: $htmLawed_config [ 'transform_anchor' ] === true ))
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{
$attribute_array [ 'href' ] = " javascript:GoToAnchor(' " . trim ( substr ( $attribute_array [ 'href' ], 1 )) . " '); " ;
}
}
// Build the attributes string
$attributes = '' ;
foreach ( $attribute_array as $k => $v ){
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$attributes .= " { $k } = \" { $v } \" " ;
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}
// Return the opening tag with attributes
static $empty_elements = array ( 'area' => 1 , 'br' => 1 , 'col' => 1 , 'embed' => 1 , 'hr' => 1 , 'img' => 1 , 'input' => 1 , 'isindex' => 1 , 'param' => 1 );
return " < { $element } { $attributes } " . ( isset ( $empty_elements [ $element ]) ? ' /' : '' ) . '>' ;
}
