H2GD Part 15: broken image in Chrome for JetPack stats

This simple slideshow demonstrates a problem with the JetPack stats plugin which results in a broken image when viewing the site using Chrome. A fix for the problem is provided for Jetpack v1.7

Links:

Admin-bar Stats image not showing up

Chrome browser does not show images generated by HTTP handler

Download the patch

Attached to this post is the fix for this problem. It’s a patch file for Jetpack version 1.7.

Explanation

• When the webpage is created Jetpack sets the source for the image in the admin bar as “http://example.com/wp-admin/admin.php?page=stats&noheader&proxy&chart=admin-bar-hours&height=20&hours=48″
• The browser performs a GET for this image
• Which sends the message to WordPress admin which invokes the JetPack stats function called stats_reports_page().
• This then sends a remote request to wordpress.com
• Which replies with the generated PNG file in the body of the response
• The Stats function then echo’ed this PNG file to the browser using the following (simplified) code
  header( "Content-Type: image/png" );
die( $get['body'] )


• Apparently Google chrome doesn’t care for this ( see the second link )
• It is happier when the code is changed to
  header( "Content-Type: image/png" );
$img = $get['body'];
header( 'Content-Length: ' . strlen( $img ) );
echo $img;
exit();

• So that’s what the patch file contains