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-rw-r--r--library/HTMLPurifier/AttrDef/CSS.php87
1 files changed, 87 insertions, 0 deletions
diff --git a/library/HTMLPurifier/AttrDef/CSS.php b/library/HTMLPurifier/AttrDef/CSS.php
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+<?php
+
+/**
+ * Validates the HTML attribute style, otherwise known as CSS.
+ * @note We don't implement the whole CSS specification, so it might be
+ * difficult to reuse this component in the context of validating
+ * actual stylesheet declarations.
+ * @note If we were really serious about validating the CSS, we would
+ * tokenize the styles and then parse the tokens. Obviously, we
+ * are not doing that. Doing that could seriously harm performance,
+ * but would make these components a lot more viable for a CSS
+ * filtering solution.
+ */
+class HTMLPurifier_AttrDef_CSS extends HTMLPurifier_AttrDef
+{
+
+ public function validate($css, $config, $context) {
+
+ $css = $this->parseCDATA($css);
+
+ $definition = $config->getCSSDefinition();
+
+ // we're going to break the spec and explode by semicolons.
+ // This is because semicolon rarely appears in escaped form
+ // Doing this is generally flaky but fast
+ // IT MIGHT APPEAR IN URIs, see HTMLPurifier_AttrDef_CSSURI
+ // for details
+
+ $declarations = explode(';', $css);
+ $propvalues = array();
+
+ /**
+ * Name of the current CSS property being validated.
+ */
+ $property = false;
+ $context->register('CurrentCSSProperty', $property);
+
+ foreach ($declarations as $declaration) {
+ if (!$declaration) continue;
+ if (!strpos($declaration, ':')) continue;
+ list($property, $value) = explode(':', $declaration, 2);
+ $property = trim($property);
+ $value = trim($value);
+ $ok = false;
+ do {
+ if (isset($definition->info[$property])) {
+ $ok = true;
+ break;
+ }
+ if (ctype_lower($property)) break;
+ $property = strtolower($property);
+ if (isset($definition->info[$property])) {
+ $ok = true;
+ break;
+ }
+ } while(0);
+ if (!$ok) continue;
+ // inefficient call, since the validator will do this again
+ if (strtolower(trim($value)) !== 'inherit') {
+ // inherit works for everything (but only on the base property)
+ $result = $definition->info[$property]->validate(
+ $value, $config, $context );
+ } else {
+ $result = 'inherit';
+ }
+ if ($result === false) continue;
+ $propvalues[$property] = $result;
+ }
+
+ $context->destroy('CurrentCSSProperty');
+
+ // procedure does not write the new CSS simultaneously, so it's
+ // slightly inefficient, but it's the only way of getting rid of
+ // duplicates. Perhaps config to optimize it, but not now.
+
+ $new_declarations = '';
+ foreach ($propvalues as $prop => $value) {
+ $new_declarations .= "$prop:$value;";
+ }
+
+ return $new_declarations ? $new_declarations : false;
+
+ }
+
+}
+
+// vim: et sw=4 sts=4