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

[Michael M Slusarz]

Quoting Chris Hastie <lists at oak-wood.co.uk>:

| 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... :)

I would rather not put ISP specific code in IMP.  We can do a lot to 
attempt to figure out the true IP address, but there is no need to overdo 
it...

michael

______________________________________________
Michael Slusarz [slusarz at bigworm.colorado.edu]
The University of Colorado at Boulder