Add request/auth package to Nomulus release

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=147087621

java/google/registry/request/auth/LegacyAuthenticationMechanism.java

@@ -0,0 +1,51 @@
+// Copyright 2017 The Nomulus Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package google.registry.request.auth;
+
+import static google.registry.request.auth.AuthLevel.NONE;
+import static google.registry.request.auth.AuthLevel.USER;
+
+import com.google.appengine.api.users.UserService;
+import com.google.common.annotations.VisibleForTesting;
+import javax.inject.Inject;
+import javax.servlet.http.HttpServletRequest;
+
+/**
+ * Authentication mechanism for legacy cookie-based App Engine authentication.
+ *
+ * <p>Just use the values returned by UserService.
+ */
+// TODO(mountford) Add XSRF protection here or elsewhere, from RequestHandler
+public class LegacyAuthenticationMechanism implements AuthenticationMechanism {
+
+  private final UserService userService;
+
+  @VisibleForTesting
+  @Inject
+  public LegacyAuthenticationMechanism(UserService userService) {
+    this.userService = userService;
+  }
+
+  @Override
+  public AuthResult authenticate(HttpServletRequest request) {
+    if (!userService.isUserLoggedIn()) {
+      return AuthResult.create(NONE);
+    } else {
+      return AuthResult.create(
+          USER,
+          UserAuthInfo.create(userService.getCurrentUser(), userService.isUserAdmin()));
+    }
+  }
+}