server_name '_' and custom error_page

[Mark Bekkers]

Hi,

This is my first time post, hi everybody.

The reason of this post is that I found some Nginx behaviour that I 
don't understand.
I would like to know if it's a bug or not.
Version: nginx/0.8.52

I pointed all DNS requests to my Nginx server (using a CNAME wildcard).
Every none matched server names are handled by the snippit below (a 
fallback server configuration)

server {
         # CONFIG
         server_name _;

         # SETTINGS
         listen 80 default;
         root /var/www/host/default/public;
     access_log /var/www/home/log/nginx/default.access.log;

     error_page 404 /error_page/404.html;
     location /error_page/ {alias /var/www/home/error_page/; allow all; 
internal;}

     }


A request to kjhtgfcdh.example.com will be catched by the fallback 
configuration and then serves
my custom defined 404 because the root directive points to an empy 
directory; thus no file is found.

This way I can inform clients (with a custom error_page) they are 
accessing the wrong host.

But this seemed wrong so I changed it to:

server {
         # CONFIG
         server_name _;

         # SETTINGS
         listen 80 default;
     access_log /var/www/home/log/nginx/default.access.log;

     error_page 404 /error_page/404.html;
     location /error_page/ {alias /var/www/home/error_page/; allow all; 
internal;}

     return 404;

     }

This is almost the same, but it has no root directive and a return 
directive.
This seems the way to do it because it skips the need to look for a file 
in the root and returns with a 404
immediately, but it doesn't serve my custom error_page. It serves the 
nginx internal 404 document.

So I changed it to:

server {
         # CONFIG
         server_name _;

         # SETTINGS
         listen 80 default;
     access_log /var/www/home/log/nginx/default.access.log;

     error_page 404 /error_page/404.html;
     location /error_page/ {alias /var/www/home/error_page/; allow all; 
internal;}

         location / {
             return 404;
         }

     }

Again no root directive but the return directive is wrapped in a 
location block and it DOES
serve my custom error_page.

My questions:
Did I found a bug? And if I did; what would be correct behaviour?
And if I did not; what is the correct behaviour in this context?


- Mark