1 files changed, 51 insertions, 0 deletions
diff --git a/actionpack/lib/action_dispatch/middleware/remote_ip.rb b/actionpack/lib/action_dispatch/middleware/remote_ip.rb
new file mode 100644
index 0000000000..c7d710b98e
--- /dev/null
+++ b/actionpack/lib/action_dispatch/middleware/remote_ip.rb
@@ -0,0 +1,51 @@
+module ActionDispatch
+  class RemoteIp
+    class IpSpoofAttackError < StandardError ; end
+
+    class RemoteIpGetter
+      def initialize(env, check_ip_spoofing, trusted_proxies)
+        @env = env
+        @check_ip_spoofing = check_ip_spoofing
+        @trusted_proxies = trusted_proxies
+      end
+
+      def remote_addrs
+        @remote_addrs ||= begin
+          list = @env['REMOTE_ADDR'] ? @env['REMOTE_ADDR'].split(/[,\s]+/) : []
+          list.reject { |addr| addr =~ @trusted_proxies }
+        end
+      end
+
+      def to_s
+        return remote_addrs.first if remote_addrs.any?
+
+        forwarded_ips = @env['HTTP_X_FORWARDED_FOR'] ? @env['HTTP_X_FORWARDED_FOR'].strip.split(/[,\s]+/) : []
+
+        if client_ip = @env['HTTP_CLIENT_IP']
+          if @check_ip_spoofing && !forwarded_ips.include?(client_ip)
+            # We don't know which came from the proxy, and which from the user
+            raise IpSpoofAttackError, "IP spoofing attack?!" \
+              "HTTP_CLIENT_IP=#{@env['HTTP_CLIENT_IP'].inspect}" \
+              "HTTP_X_FORWARDED_FOR=#{@env['HTTP_X_FORWARDED_FOR'].inspect}"
+          end
+          return client_ip
+        end
+
+        return forwarded_ips.reject { |ip| ip =~ @trusted_proxies }.last || @env["REMOTE_ADDR"]
+      end
+    end
+
+    def initialize(app, check_ip_spoofing = true, trusted_proxies = nil)
+      @app = app
+      @check_ip_spoofing = check_ip_spoofing
+      regex = '(^127\.0\.0\.1$|^(10|172\.(1[6-9]|2[0-9]|30|31)|192\.168)\.)'
+      regex << "|(#{trusted_proxies})" if trusted_proxies
+      @trusted_proxies = Regexp.new(regex, "i")
+    end
+
+    def call(env)
+      env["action_dispatch.remote_ip"] = RemoteIpGetter.new(env, @check_ip_spoofing, @trusted_proxies)
+      @app.call(env)
+    end
+  end
+end
+\ No newline at end of file