symfony/symfony — pull request #2695 by pulzarraider (2011-11-22 21:29:45+00:00)
Title: [HttpFoundation] Get correct client IP when using trusted proxy (Varnish)

Bug fix: yes
Feature addition: no
Backwards compatibility break: no
Symfony2 tests pass: yes
Fixes the following tickets: -
Todo: -
Note: This is reopened PR #2686 for 2.0 branch.

If using trusted proxy (Varnish, ...) the client IP must be identified from X-Forwarded-For header. The header has de-facto standard format:

X-Forwarded-For : client1, proxy1, proxy2,

where the value is a comma+space separated list of IP addresses, the left-most being the farthest downstream client, and each successive proxy that passed the request adding the IP address where it received the request from. See: http://en.wikipedia.org/wiki/X-Forwarded-For

Function getClientIp should return only one client IP, not a list of all nonimportant IPs as it's now. Similar example can be seen in Cake framework: http://api.cakephp.org/view_source/request-handler-component/#line-477

There are many ways how to chose the first IP from X-Forwarded-For header. Any other faster and more reliable way is welcome.