Redirect to custom landing pages based on http referer

[justink101]

Is it possible using nginx to essentially look at the http referer header,
and if its set to a specific value, and the page is index.html or /,
redirect to a custom landing page.

For example:

# Psuedo code
if($page = "index.html" and $http_referer ~* (www\.)?amazon.com.*) {
     rewrite ^ "our-amazon-landing-page.html" permanent;
}

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,250656,250656#msg-250656