mirror of https://github.com/friendica/friendica
88 lines
3.0 KiB
PHP
88 lines
3.0 KiB
PHP
<?php
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/**
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* Validates the HTML attribute style, otherwise known as CSS.
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* @note We don't implement the whole CSS specification, so it might be
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* difficult to reuse this component in the context of validating
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* actual stylesheet declarations.
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* @note If we were really serious about validating the CSS, we would
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* tokenize the styles and then parse the tokens. Obviously, we
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* are not doing that. Doing that could seriously harm performance,
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* but would make these components a lot more viable for a CSS
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* filtering solution.
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*/
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class HTMLPurifier_AttrDef_CSS extends HTMLPurifier_AttrDef
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{
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public function validate($css, $config, $context) {
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$css = $this->parseCDATA($css);
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$definition = $config->getCSSDefinition();
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// we're going to break the spec and explode by semicolons.
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// This is because semicolon rarely appears in escaped form
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// Doing this is generally flaky but fast
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// IT MIGHT APPEAR IN URIs, see HTMLPurifier_AttrDef_CSSURI
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// for details
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$declarations = explode(';', $css);
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$propvalues = array();
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/**
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* Name of the current CSS property being validated.
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*/
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$property = false;
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$context->register('CurrentCSSProperty', $property);
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foreach ($declarations as $declaration) {
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if (!$declaration) continue;
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if (!strpos($declaration, ':')) continue;
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list($property, $value) = explode(':', $declaration, 2);
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$property = trim($property);
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$value = trim($value);
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$ok = false;
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do {
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if (isset($definition->info[$property])) {
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$ok = true;
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break;
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}
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if (ctype_lower($property)) break;
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$property = strtolower($property);
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if (isset($definition->info[$property])) {
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$ok = true;
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break;
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}
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} while(0);
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if (!$ok) continue;
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// inefficient call, since the validator will do this again
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if (strtolower(trim($value)) !== 'inherit') {
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// inherit works for everything (but only on the base property)
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$result = $definition->info[$property]->validate(
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$value, $config, $context );
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} else {
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$result = 'inherit';
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}
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if ($result === false) continue;
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$propvalues[$property] = $result;
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}
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$context->destroy('CurrentCSSProperty');
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// procedure does not write the new CSS simultaneously, so it's
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// slightly inefficient, but it's the only way of getting rid of
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// duplicates. Perhaps config to optimize it, but not now.
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$new_declarations = '';
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foreach ($propvalues as $prop => $value) {
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$new_declarations .= "$prop:$value;";
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}
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return $new_declarations ? $new_declarations : false;
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}
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}
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// vim: et sw=4 sts=4
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