error_page and named locations

[Igor Sysoev]

On Wed, Dec 10, 2008 at 02:32:51PM +0000, cynix wrote:

> I have the following config on 0.7.26:
> 
> server {
>  ...
> 
>  location / {

You may want to add this here:

    log_not_found   off;

>   error_page 404 = @cms;
>  }
> 
>  location @cms {
>   fastcgi_pass 127.0.0.1:1234;
>   include fastcgi_params;
>   fastcgi_param SCRIPT_FILENAME /www_root/index.php;
>   fastcgi_param SCRIPT_NAME /index.php;
>  }
> 
>  location ~ \.php$ {
>   fastcgi_pass 127.0.0.1:1234;
>   include fastcgi_params;
>   fastcgi_param SCRIPT_FILENAME /www_root$fastcgi_script_name;
>   fastcgi_param SCRIPT_NAME $fastcgi_script_name;
>   fastcgi_intercept_errors on;
>   error_page 404 = @cms;
>  }
> 
>  ...
> }
> 
> This should pass all requests to non-existent paths to /index.php so "clean
> URLs" will work and the CMS will display the corresponding pages. Indeed it
> works if I try to access a URI that is first handled by the "location /" block,
> such as http://my.com/2008/12/my-blog-post.
> 
> However, when I access a URI that is first handled by the "location ~ \.php$"
> block, such as http://my.com/non-existent.php, theoretically nginx will first
> pass this request to FastCGI, then PHP sends back 404 because it can't find the
> non-existent.php file, then nginx should honor the error_page directive and send
> the request to @cms. In reality it results in a 502 Bad Gateway. The error log
> says "upstream sent invalid header while reading response header from upstream".
> But if I used the following:
> 
>  location ~ \.php$ {
>   
>   error_page 404 = /index.php;
>  }
> 
> Then it will work as intended.
> 
> Why can't I use a named location for error_page if the location block contains a
> fastcgi_pass directive? (I assume this is the case for proxy_pass too, but I
> didn't test that one.)

The attached patch fixes the bug.


-- 
Igor Sysoev
http://sysoev.ru/en/
-------------- next part --------------
Index: src/http/modules/ngx_http_fastcgi_module.c
===================================================================
--- src/http/modules/ngx_http_fastcgi_module.c	(revision 1713)
+++ src/http/modules/ngx_http_fastcgi_module.c	(working copy)
@@ -419,6 +419,8 @@
         return NGX_HTTP_INTERNAL_SERVER_ERROR;
     }
 
+    ngx_http_set_ctx(r, NULL, ngx_http_fastcgi_module);
+
     u = ngx_pcalloc(r->pool, sizeof(ngx_http_upstream_t));
     if (u == NULL) {
         return NGX_HTTP_INTERNAL_SERVER_ERROR;