Trouble with a complex rewrite

[Wilson Bilkovich]

On 4/2/07, Igor Sysoev <is at rambler-co.ru> wrote:
> On Mon, Apr 02, 2007 at 07:41:09AM -0400, Wilson Bilkovich wrote:
>
> > I am migrating an existing Apache 2.2.4 -> Mongrel configuration to Nginx.
> > Everything is working fine save for one final piece.
> >
> > We have a complicated rule that redirects some traffic to a partner
> > site based on the contents of the query string. At the moment, this is
> > still a requirement, and I can't do away with it.
> >
> > The existing Apache rule is:
> >
> > RewriteCond %{QUERY_STRING} message=.*(%\d+|\b)(foo|bar|baz|qux)(%\d+|\b)
> > [NC]
> > RewriteRule ^/api/receive
> > http://target.example.com/horrible/url/?%{QUERY_STRING} [P,L,NC]
> >
> > The nasty piece here is that "%\d+" in the regexp pattern is
> > necessary. 'foo' should only match if it is a whole word in the query
> > string.
> > (%\d+|\b) allows the pattern to handle either normal word boundaries,
> > or HTML-encoded entities like %20.
> > For example:
> > api/receive?message=foo%20hello should match this rule, but:
> > api/receive?message=hellofoo should not
> >
> > Is it possible to duplicate this in nginx?
> > Thus far I have tried:
> > 1. Making a location {} entry for api/receive, and using if
> > ($query_string ~ pattern)
> > 2. Using if($query_string) inside the / location block
> > 3. Making a location entry for the regexp on its own
> > 4. Testing with simply message=.*foo as the pattern, which makes me
> > think the problem is more basic than the regexp pattern
> >
> > None of these seem to work.
> > I've tried both "~" and "~*" styles, though I haven't actually been
> > able to figure out what the difference between them is.
>
>         location /api/receive {
>             if ($args ~ "message=.*(%\d+|\b)(foo|bar|baz|qux)(%\d+|\b)") {
>                 rewrite  ^   http://target.example.com/horrible/url/;
>             }
>         }
>

Thank you for the reply.
That syntax will do a 302 redirect though, correct? I need to actually
proxy the request to the target server.
The "~" operator means 'does this pattern occur in the string'.. How
does ~* differ from that? I've seen the two operators used in
examples.

--Wilson