2 files changed, 10 insertions, 7 deletions
diff --git a/actionpack/lib/action_dispatch/middleware/remote_ip.rb b/actionpack/lib/action_dispatch/middleware/remote_ip.rb
index 030ccb2017..d924f21fad 100644
--- a/actionpack/lib/action_dispatch/middleware/remote_ip.rb
+++ b/actionpack/lib/action_dispatch/middleware/remote_ip.rb
@@ -18,11 +18,13 @@ module ActionDispatch
     def initialize(app, check_ip_spoofing = true, custom_proxies = nil)
       @app = app
       @check_ip = check_ip_spoofing
-      if custom_proxies
-        custom_regexp = Regexp.new(custom_proxies)
-        @proxies = Regexp.union(TRUSTED_PROXIES, custom_regexp)
+      @proxies = case custom_proxies
+      when Regexp
+        custom_proxies
+      when nil
+        TRUSTED_PROXIES
       else
-        @proxies = TRUSTED_PROXIES
+        Regexp.union(TRUSTED_PROXIES, custom_proxies)
       end
     end
 
@@ -57,7 +59,7 @@ module ActionDispatch
             "HTTP_X_FORWARDED_FOR=#{@env['HTTP_X_FORWARDED_FOR'].inspect}"
         end
 
-        not_proxy = client_ip || forwarded_ips.last || remote_addrs.first
+        not_proxy = client_ip || forwarded_ips.first || remote_addrs.first
 
         # Return first REMOTE_ADDR if there are no other options
         not_proxy || ips_from('REMOTE_ADDR', :allow_proxies).first
diff --git a/actionpack/lib/action_dispatch/middleware/stack.rb b/actionpack/lib/action_dispatch/middleware/stack.rb
index a4308f528c..28e8fbdab8 100644
--- a/actionpack/lib/action_dispatch/middleware/stack.rb
+++ b/actionpack/lib/action_dispatch/middleware/stack.rb
@@ -93,8 +93,9 @@ module ActionDispatch
     end
 
     def swap(target, *args, &block)
-      insert_before(target, *args, &block)
-      delete(target)
+      index = assert_index(target, :before)
+      insert(index, *args, &block)
+      middlewares.delete_at(index + 1)
     end
 
     def delete(target)