File.php

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<?php

namespace Elgg\FileService;

use Elgg\Security\Base64Url;

class File {

    const INLINE = 'inline';
    const ATTACHMENT = 'attachment';

    private $file;

    private $expires;

    private $disposition;

    private $use_cookie = true;

    public function setFile(\ElggFile $file) {
        $this->file = $file;
    }

    public function getFile() {
        return $this->file;
    }

    public function setExpires($expires = '+2 hours') {
        $this->expires = strtotime($expires);
    }

    public function setDisposition($disposition = self::ATTACHMENT) {
        if (!in_array($disposition, array(self::ATTACHMENT, self::INLINE))) {
            throw new \InvalidArgumentException("Disposition $disposition is not supported in " . __CLASS__);
        }
        $this->disposition = $disposition;
    }

    public function bindSession($use_cookie = true) {
        $this->use_cookie = $use_cookie;
    }

    public function getURL() {

        if (!$this->file instanceof \ElggFile || !$this->file->exists()) {
            elgg_log("Unable to resolve resource URL for a file that does not exist on filestore");
            return false;
        }

        $relative_path = '';
        $root_prefix = _elgg_services()->config->getDataPath();
        $path = $this->file->getFilenameOnFilestore();
        if (substr($path, 0, strlen($root_prefix)) == $root_prefix) {
            $relative_path = substr($path, strlen($root_prefix));
        }

        if (!$relative_path) {
            elgg_log("Unable to resolve relative path of the file on the filestore");
            return false;
        }

        if (preg_match('~[^a-zA-Z0-9_\./ ]~', $relative_path)) {
            // Filenames may contain special characters that result in malformatted URLs
            // and/or HMAC mismatches. We want to avoid that by encoding the path.
            $relative_path = ':' . Base64Url::encode($relative_path);
        }

        $data = array(
            'expires' => isset($this->expires) ? $this->expires : 0,
            'last_updated' => filemtime($this->file->getFilenameOnFilestore()),
            'disposition' => $this->disposition == self::INLINE ? 'i' : 'a',
            'path' => $relative_path,
        );

        if ($this->use_cookie) {
            $data['cookie'] = _elgg_services()->session->getId();
            if (empty($data['cookie'])) {
                return false;
            }
            $data['use_cookie'] = 1;
        } else {
            $data['use_cookie'] = 0;
        }

        ksort($data);
        $mac = _elgg_services()->crypto->getHmac($data)->getToken();

        $url_segments = array(
            'serve-file',
            "e{$data['expires']}",
            "l{$data['last_updated']}",
            "d{$data['disposition']}",
            "c{$data['use_cookie']}",
            $mac,
            $relative_path,
        );

        return elgg_normalize_url(implode('/', $url_segments));
    }
}