add x-forwarded-for header to the client

This adds the way to find out the actual ip of the client machine, even
if it is hidden behind a local reverse proxy.

lib/zero/request/client.rb

@@ -4,6 +4,8 @@ module Zero
     class Client
       # the key for the ip of the client
       KEY_REMOTE_ADDR = 'REMOTE_ADDR'
+      # in proxy setups, this is the real address of the client
+      KEY_FORWARDED_FOR = 'X_FORWARDED_FOR'
       # the key for the hostname
       KEY_REMOTE_HOST = 'REMOTE_HOST'
       # the key for the user agent
@@ -12,7 +14,10 @@ module Zero
       # creates a new client with the data of the request environment
       # @param environment a hash representation of the request
       def initialize(environment)
-        @address    = environment[KEY_REMOTE_ADDR]
+        # extract the two possible ips
+        @forwarded_for  = environment[KEY_FORWARDED_FOR]
+        @remote_address = environment[KEY_REMOTE_ADDR]
+        @address    = forwarded_for || remote_address
         @hostname   = environment[KEY_REMOTE_HOST]
         @user_agent = environment[KEY_USER_AGENT]
       end
@@ -26,6 +31,14 @@ module Zero
       # the user agent of the client
       # @return [String] the user agent of the client
       attr_reader :user_agent
+
+      # get the forwarded address, set in proxy setups
+      # @return [String] the address set in KEY_FORWARDED_FOR header
+      attr_reader :forwarded_for
+
+      # get the remote address given by KEY_REMOTE_ADDR
+      # @return [String] the remote address defined in KEY_REMOTE_ADDR header
+      attr_reader :remote_address
     end
   end
 end

spec/unit/zero/request/client/address_spec.rb

@@ -2,8 +2,26 @@ require 'spec_helper'
 
 describe Zero::Request::Client, '#address' do
   subject { Zero::Request::Client.new(env) }
-  let(:address) { '127.0.0.1' }
-  let(:env) { {'REMOTE_ADDR' => address} }
 
-  its(:address) { should == address }
+  context 'without a proxy' do
+    let(:address) { '127.0.0.1' }
+    let(:env) { {'REMOTE_ADDR' => address} }
+
+    its(:address) { should == address }
+  end
+
+  context 'with a proxy' do
+    let(:proxy)   { '127.0.0.1' }
+    let(:address) { '192.168.42.3' }
+    let(:env) do
+      {
+        'REMOTE_ADDR' => proxy,
+        'X_FORWARDED_FOR' => address
+      }
+    end
+
+    its(:address) { should == address }
+    its(:remote_address) { should == proxy }
+    its(:forwarded_for)  { should == address }
+  end
 end