Inconsistent behavior with Nginx's auth_request_set and more_set_input_headers

Server NGINX
1

Hi,

I’m trying to use the auth_request module in conjunction with the
more_set_input_headers to automatically login my users into web apps.

Basically, it works like this:

  1. Users have some session cookie that authenticates them.
  2. I have a PHP script (auth.php) that validates the cookie and returns
    their proper username as a response header.
  3. Nginx calls auth.php with auth_request, and sets the username in a
    variable.
  4. Nginx then calls the web app with a request header set to the correct
    username.
  5. The web app reads the header, and logs the user in.

This works, but strangely inconsistent. The issue is that when a user
accesses the web app on /app/, it works (the request header is sent),
but when the app is accesssed on /app/index.php, it never receives the
header from nginx.

I’ve created a mock configuration that reproduces the error. It doesn’t
matter if I use a browser or cURL; both give the same behavior.

I thought it’d be a bit hard to view configuration files on a mailing
list, so I’ve created a topic on ServerFault. Reply whichever way you
like best. Topic is here:

Thanks a lot! This issue has kept me up for a few days now already.

2

Hello!

On Sat, Jun 28, 2014 at 05:35:27PM +0000, [email protected] wrote:

  1. Nginx calls auth.php with auth_request, and sets the username in a
    variable.
  2. Nginx then calls the web app with a request header set to the correct
    username.
  3. The web app reads the header, and logs the user in.

This works, but strangely inconsistent. The issue is that when a user
accesses the web app on /app/, it works (the request header is sent), but
when the app is accesssed on /app/index.php, it never receives the header
from nginx.

This behaviour is likely due to the fact that
“more_set_input_headers” handler is executed before access phase
(where auth_request works), and hence only changes a request if
it’s internally redirected.

Solution to the problem is to stop using “more_set_input_headers”
(it’s anyway very wrong, request headers shouldn’t be changed) and
use native “fastcgi_param” instead:

fastcgi_param HTTP_X_TEST_HEADER $auth_header;

Will link this answer there.

–
Maxim D.
http://nginx.org/