function drupal_page_header

Set HTTP headers in preparation for a page response.

File

includes/bootstrap.inc, line 418

Functions that need to be loaded on every Drupal request.

Code

function drupal_page_header() {
  if (variable_get('dev_timer', 0)) {
    timer_start();
  }
  if (variable_get('cache', 0)) {
    if ($cache = page_get_cache()) {
      bootstrap_invoke_all('init');

      // Set default values:
      $date = gmdate('D, d M Y H:i:s', $cache->created) . ' GMT';
      $etag = '"' . md5($date) . '"';

      // Check http headers:
      $modified_since = isset($_SERVER['HTTP_IF_MODIFIED_SINCE']) ? $_SERVER['HTTP_IF_MODIFIED_SINCE'] == $date : NULL;
      if (!empty($_SERVER['HTTP_IF_MODIFIED_SINCE']) && ($timestamp = strtotime($_SERVER['HTTP_IF_MODIFIED_SINCE'])) != -1) {
        $modified_since = $cache->created <= $timestamp;
      }
      else {
        $modified_since = NULL;
      }
      $none_match = !empty($_SERVER['HTTP_IF_NONE_MATCH']) ? $_SERVER['HTTP_IF_NONE_MATCH'] == $etag : NULL;

      // The type checking here is very important, be careful when changing entries.
      if (($modified_since !== NULL || $none_match !== NULL) && $modified_since !== false && $none_match !== false) {
        header('HTTP/1.0 304 Not Modified');
        exit;
      }

      // Send appropriate response:
      header("Last-Modified: {$date}");
      header("ETag: {$etag}");

      // Determine if the browser accepts gzipped data.
      if (@strpos($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip') === false && function_exists('gzencode')) {

        // Strip the gzip header and run uncompress.
        $cache->data = gzinflate(substr(substr($cache->data, 10), 0, -8));
      }
      elseif (function_exists('gzencode')) {
        header('Content-Encoding: gzip');
      }

      // Send the original request's headers.  We send them one after
      // another so PHP's header() function can deal with duplicate
      // headers.
      $headers = explode("\n", $cache->headers);
      foreach ($headers as $header) {
        header($header);
      }
      print $cache->data;
      bootstrap_invoke_all('exit');
      exit;
    }
    else {
      header("Expires: Sun, 19 Nov 1978 05:00:00 GMT");
      header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
      header("Cache-Control: no-store, no-cache, must-revalidate");
      header("Cache-Control: post-check=0, pre-check=0", false);
      header("Pragma: no-cache");
    }
  }
}