CORS Headers Not Being Set

Question

I'm trying to download a static file from another domain. In my .htaccess file, which is in the root directory:

Header set Access-Control-Allow-Origin "*"
Header set Access-Control-Allow-Headers "Accept, If-Modified-Since, Origin"
Header set Access-Control-Allow-Methods "GET, OPTIONS"

And here's the request-response cycle where a browser downloads the resource twice:

GET /file HTTP/1.1
Host: www.example.com
Accept: application/json
Origin: http://www.mydomain.com

HTTP/1.1 200 OK
Date: Sat, 07 Sep 2013 21:01:35 GMT
Server: Apache
Last-Modified: Sat, 07 Sep 2013 20:14:45 GMT
Content-Length: 2
Access-Control-Allow-Origin: *
Access-Control-Allow-Headers: Accept, If-Modified-Since, Origin
Access-Control-Allow-Methods: GET, OPTIONS
Content-Type: application/json

[]

GET /file HTTP/1.1
Host: www.example.com
Cache-Control: max-age=0
Accept: application/json
Origin: http://www.mydomain.com
If-Modified-Since: Sat, 07 Sep 2013 20:14:45 GMT

HTTP/1.1 304 Not Modified
Date: Sat, 07 Sep 2013 21:01:40 GMT
Server: Apache

The second time you can see that since the file hasn't been modified, the server responds with a 304 Not Modified. Why are the CORS headers not being set for the second response?

Answer 1

It's an apache bug, see below

https://issues.apache.org/bugzilla/show_bug.cgi?id=51223

You can recompile Apache with the patch if you're feeling brave....