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<?php
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/**
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 * Implements data: URI for base64 encoded images supported by GD.
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 */
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class HTMLPurifier_URIScheme_data extends HTMLPurifier_URIScheme
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{
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    /**
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     * @type bool
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     */
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    public $browsable = true;
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    /**
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     * @type array
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     */
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    public $allowed_types = array(
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        // you better write validation code for other types if you
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        // decide to allow them
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        'image/jpeg' => true,
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        'image/gif' => true,
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        'image/png' => true,
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    );
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    // this is actually irrelevant since we only write out the path
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    // component
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    /**
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     * @type bool
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     */
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    public $may_omit_host = true;
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    /**
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     * @param HTMLPurifier_URI $uri
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     * @param HTMLPurifier_Config $config
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     * @param HTMLPurifier_Context $context
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     * @return bool
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     */
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    public function doValidate(&$uri, $config, $context)
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    {
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        $result = explode(',', $uri->path, 2);
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        $is_base64 = false;
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        $charset = null;
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        $content_type = null;
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        if (count($result) == 2) {
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            list($metadata, $data) = $result;
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            // do some legwork on the metadata
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            $metas = explode(';', $metadata);
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            while (!empty($metas)) {
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                $cur = array_shift($metas);
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                if ($cur == 'base64') {
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                    $is_base64 = true;
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                    break;
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                }
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                if (substr($cur, 0, 8) == 'charset=') {
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                    // doesn't match if there are arbitrary spaces, but
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                    // whatever dude
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                    if ($charset !== null) {
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                        continue;
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                    } // garbage
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                    $charset = substr($cur, 8); // not used
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                } else {
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                    if ($content_type !== null) {
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                        continue;
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                    } // garbage
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                    $content_type = $cur;
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                }
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            }
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        } else {
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            $data = $result[0];
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        }
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        if ($content_type !== null && empty($this->allowed_types[$content_type])) {
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            return false;
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        }
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        if ($charset !== null) {
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            // error; we don't allow plaintext stuff
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            $charset = null;
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        }
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        $data = rawurldecode($data);
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        if ($is_base64) {
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            $raw_data = base64_decode($data);
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        } else {
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            $raw_data = $data;
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        }
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        if ( strlen($raw_data) < 12 ) {
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            // error; exif_imagetype throws exception with small files,
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            // and this likely indicates a corrupt URI/failed parse anyway
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            return false;
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        }
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        // XXX probably want to refactor this into a general mechanism
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        // for filtering arbitrary content types
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        if (function_exists('sys_get_temp_dir')) {
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            $file = tempnam(sys_get_temp_dir(), "");
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        } else {
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            $file = tempnam("/tmp", "");
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        }
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        file_put_contents($file, $raw_data);
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        if (function_exists('exif_imagetype')) {
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            $image_code = exif_imagetype($file);
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            unlink($file);
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        } elseif (function_exists('getimagesize')) {
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            set_error_handler(array($this, 'muteErrorHandler'));
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            $info = getimagesize($file);
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            restore_error_handler();
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            unlink($file);
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            if ($info == false) {
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                return false;
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            }
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            $image_code = $info[2];
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        } else {
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            trigger_error("could not find exif_imagetype or getimagesize functions", E_USER_ERROR);
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        }
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        $real_content_type = image_type_to_mime_type($image_code);
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        if ($real_content_type != $content_type) {
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            // we're nice guys; if the content type is something else we
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            // support, change it over
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            if (empty($this->allowed_types[$real_content_type])) {
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                return false;
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            }
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            $content_type = $real_content_type;
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        }
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        // ok, it's kosher, rewrite what we need
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        $uri->userinfo = null;
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        $uri->host = null;
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        $uri->port = null;
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        $uri->fragment = null;
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        $uri->query = null;
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        $uri->path = "$content_type;base64," . base64_encode($raw_data);
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        return true;
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    }
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    /**
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     * @param int $errno
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     * @param string $errstr
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     */
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    public function muteErrorHandler($errno, $errstr)
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    {
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    }
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}