unparsed_uri setting in ngx_http_subrequest?

[Maxim Dounin]

Hello!

On Fri, Feb 26, 2010 at 11:57:36AM -0800, Brian Pane wrote:

> In ngx_http_subrequest, the newly initialized subrequest's
> unparsed_uri is set to the same value as the parent request's
> unparsed_uri.  (I'm looking at 0.8.33.)

This is believed to be right thing to do.  Unparsed uri is one got 
from client, and it shouldn't change on internal redirects and 
subrequests.

> This interacts in a bad way with the proxy module.  The proxy code
> that builds the request to the upstream, in ngx_http_proxy_eval, uses
> the subrequest's unparsed_uri, rather than its uri.
> 
> The result is that, if a request for /prefix/foo creates a subrequest
> for /prefix/bar, and the server has been configured to proxy /prefix/*
> to some upstream, the subrequest will result in an upstream request
> for /prefix/foo (the same URI as the parent request) rather than
> /prefix/foo.
> 
> Is that a bug, or is it the intended behavior?

It's (mis?)feature of proxy_pass used with variables.  Until 
0.8.25 it was required to construct full url there.  In 0.8.25 it 
was changed to use $request_uri if only hostname is given.

Most likely it should follow the same pattern as others when 
working with r->unparsed_uri, i.e. don't use it unless it's valid 
and don't use it in subrequests (see ngx_http_proxy_create_request() 
for an example).

Maxim Dounin