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https://github.com/ezyang/htmlpurifier.git
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d3abcb90e3
The new logic is as follows:
* Given a URL to insert into url(), check that it is properly URL
encoded (in particular, a doublequote and backslash never occurs
within it) and then place it as url("http://example.com").
* Given a font name, if it is strictly alphanumeric, it is safe to omit
quotes. Otherwise, wrap in double quotes and replace '"' with '\22 '
(note trailing space) and '\' with '\5C ' (ditto).
We introduce expandCSSEscape() which is a hack for common parsing
idioms in CSS; this means that CSS escapes are now recognized inside
URLs as well as unquoted font names.
Signed-off-by: Edward Z. Yang <ezyang@mit.edu>
53 lines
1.7 KiB
PHP
53 lines
1.7 KiB
PHP
<?php
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/**
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* Validates a URI in CSS syntax, which uses url('http://example.com')
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* @note While theoretically speaking a URI in a CSS document could
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* be non-embedded, as of CSS2 there is no such usage so we're
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* generalizing it. This may need to be changed in the future.
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* @warning Since HTMLPurifier_AttrDef_CSS blindly uses semicolons as
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* the separator, you cannot put a literal semicolon in
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* in the URI. Try percent encoding it, in that case.
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*/
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class HTMLPurifier_AttrDef_CSS_URI extends HTMLPurifier_AttrDef_URI
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{
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public function __construct() {
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parent::__construct(true); // always embedded
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}
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public function validate($uri_string, $config, $context) {
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// parse the URI out of the string and then pass it onto
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// the parent object
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$uri_string = $this->parseCDATA($uri_string);
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if (strpos($uri_string, 'url(') !== 0) return false;
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$uri_string = substr($uri_string, 4);
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$new_length = strlen($uri_string) - 1;
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if ($uri_string[$new_length] != ')') return false;
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$uri = trim(substr($uri_string, 0, $new_length));
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if (!empty($uri) && ($uri[0] == "'" || $uri[0] == '"')) {
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$quote = $uri[0];
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$new_length = strlen($uri) - 1;
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if ($uri[$new_length] !== $quote) return false;
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$uri = substr($uri, 1, $new_length - 1);
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}
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$uri = $this->expandCSSEscape($uri);
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$result = parent::validate($uri, $config, $context);
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if ($result === false) return false;
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// extra sanity check; should have been done by URI
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$result = str_replace(array('"', "\\", "\n", "\x0c", "\r"), "", $result);
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return "url(\"$result\")";
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}
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}
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// vim: et sw=4 sts=4
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