I need to create proxy web using nginx. If I access http://myweb.com/http://www.target.com/ the proxy_pass should be http://www.target.com/

Here is my configuration:

location / {
    proxy_pass $request_uri;
    proxy_cache_methods GET;
    proxy_set_header   Referer   "$request_uri";
    proxy_redirect off;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_ignore_headers  Cache-Control;
    proxy_hide_header Pragma;
    proxy_hide_header Set-Cookie;
    proxy_set_header Cache-Control Public;
    proxy_cache cache;
    proxy_cache_valid  200 10h;
    proxy_cache_valid  301 302 1h;
    proxy_cache_valid any 1h;
}

Here is the log error

2013/02/05 12:58:51 [error] 2118#0: *8 invalid URL prefix in "/http://www.target.com/", client: 108.59.8.83, server: myweb.com, request: "HEAD /http://www.target.com/ HTTP/1.1", host: "myweb.com"