[imp] Fix for Headers.php with multiple http proxies

[Chris Hastie]

On Fri, 10 Jan 2003, Jon Knepher <jbk at wild-e.com> wrote
>
>For CVS HEAD.  A notice and bad Received line is inserted when a message goes
>through 2 or more http proxies.  This discards the middle proxy addresses and
>uses the client's ip address.
>
On the subject of proxies and Headers.php...

I'm unfortunate enough to live behind a transparent proxy. This does not 
use the X-Forwarded-For header, but instead a Client-IP header. So far, 
easy enough, but it gets worse (it would - it's ntl:)

Some of ntl:'s transparent proxies include the client's IP address 'as 
is' in the Client-IP header. Others (and the one I'm behind has just 
changed), reverse the order of the blocks. Eg, my IP address is 
currently 213.107.48.23, I see

HTTP_CLIENT_IP      : 27.48.107.213

I think, but am not sure, that whether IP addresses are reversed or not 
is detectable by a trailing -R in the proxy's version:

HTTP_VIA            : HTTP/1.1 ntl_site[C0A80107] (Traffic-Server/5.2.0-R [uSc ])

There's a list of the characteristics of different ntl: proxies at 
<http://homepage.ntlworld.com/adf/ntlproxies.html>.

So there's a challenge... :)
-- 
Chris Hastie