api: server: check for unauthorized error

This functionality has been fixed by
7bca93218291767c5dd8782de0ad630dbcda9995 but then it has been broken
again by a793564b2591035aec5412fbcbcccf220c773a4c and finally refixed
here.

Basically the functionality was to prompt for login when trying to pull
from the official docker hub.

Signed-off-by: Antonio Murdaca <runcom@redhat.com>
(cherry picked from commit 4316ae2ed33d158e1d8d994646a75e25a70d9320)

api/server/httputils/errors.go

@@ -52,6 +52,7 @@ func WriteError(w http.ResponseWriter, err error) {
 			"conflict":              http.StatusConflict,
 			"impossible":            http.StatusNotAcceptable,
 			"wrong login/password":  http.StatusUnauthorized,
+			"unauthorized":          http.StatusUnauthorized,
 			"hasn't been activated": http.StatusForbidden,
 		} {
 			if strings.Contains(errStr, keyword) {

api/server/router/image/image_routes.go

@@ -7,11 +7,9 @@ import (
 	"fmt"
 	"io"
 	"net/http"
-	"net/url"
 	"strings"
 
 	"github.com/docker/distribution/digest"
-	"github.com/docker/distribution/registry/api/errcode"
 	"github.com/docker/docker/api/server/httputils"
 	"github.com/docker/docker/builder/dockerfile"
 	"github.com/docker/docker/pkg/ioutils"
@@ -132,12 +130,6 @@ func (s *imageRouter) postImagesCreate(ctx context.Context, w http.ResponseWrite
 				err = s.backend.PullImage(ctx, ref, metaHeaders, authConfig, output)
 			}
 		}
-		// Check the error from pulling an image to make sure the request
-		// was authorized. Modify the status if the request was
-		// unauthorized to respond with 401 rather than 500.
-		if err != nil && isAuthorizedError(err) {
-			err = errcode.ErrorCodeUnauthorized.WithMessage(fmt.Sprintf("Authentication is required: %s", err))
-		}
 	} else { //import
 		var newRef reference.Named
 		if repo != "" {
@@ -389,16 +381,3 @@ func (s *imageRouter) getImagesSearch(ctx context.Context, w http.ResponseWriter
 	}
 	return httputils.WriteJSON(w, http.StatusOK, query.Results)
 }
-
-func isAuthorizedError(err error) bool {
-	if urlError, ok := err.(*url.Error); ok {
-		err = urlError.Err
-	}
-
-	if dError, ok := err.(errcode.Error); ok {
-		if dError.ErrorCode() == errcode.ErrorCodeUnauthorized {
-			return true
-		}
-	}
-	return false
-}