From 39c3f460062a7641243b2c5da3069d296c21c59f Mon Sep 17 00:00:00 2001
From: HuKeping <hukeping@huawei.com>
Date: Tue, 29 Mar 2016 21:18:07 +0800
Subject: [PATCH] Tiny refactor

It is a little wired to use "err.ServeHTTP". Via the sample from
docker/distribution, we can use "challenge" as the variable name here.

Signed-off-by: Hu Keping <hukeping@huawei.com>
---
 utils/http.go | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/utils/http.go b/utils/http.go
index d9a1357972..95245d9fb2 100644
--- a/utils/http.go
+++ b/utils/http.go
@@ -64,8 +64,10 @@ func (root *rootHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		var authCtx context.Context
 		var err error
 		if authCtx, err = root.auth.Authorized(ctx, access...); err != nil {
-			if err, ok := err.(auth.Challenge); ok {
-				err.ServeHTTP(w, r)
+			if challenge, ok := err.(auth.Challenge); ok {
+				// Let the challenge write the response.
+				challenge.ServeHTTP(w, r)
+
 				w.WriteHeader(http.StatusUnauthorized)
 				return
 			}