+ end
+
+ token_uuid_prefix = token_uuid[0..4]
+ if token_uuid_prefix == Rails.configuration.ClusterID
+ # Token is supposedly issued by local cluster, but if the
+ # token were valid, we would have been found in the database
+ # in the above query.
+ return nil
+ elsif token_uuid_prefix.length != 5
+ # malformed
+ return nil
+ end
+
+ # Invariant: token_uuid_prefix != Rails.configuration.ClusterID
+ #
+ # In other words the remaing code in this method below is the
+ # case that determines whether to accept a token that was issued
+ # by a remote cluster when the token absent or expired in our
+ # database. To begin, we need to ask the cluster that issued
+ # the token to [re]validate it.
+ clnt = ApiClientAuthorization.make_http_client(uuid_prefix: token_uuid_prefix)
+
+ host = remote_host(uuid_prefix: token_uuid_prefix)
+ if !host
+ Rails.logger.warn "remote authentication rejected: no host for #{token_uuid_prefix.inspect}"
+ return nil
+ end
+
+ begin
+ remote_user = SafeJSON.load(
+ clnt.get_content('https://' + host + '/arvados/v1/users/current',
+ {'remote' => Rails.configuration.ClusterID},
+ {'Authorization' => 'Bearer ' + token}))
+ rescue => e
+ Rails.logger.warn "remote authentication with token #{token.inspect} failed: #{e}"
+ return nil
+ end
+
+ # Check the response is well formed.
+ if !remote_user.is_a?(Hash) || !remote_user['uuid'].is_a?(String)
+ Rails.logger.warn "remote authentication rejected: remote_user=#{remote_user.inspect}"
+ return nil
+ end
+
+ remote_user_prefix = remote_user['uuid'][0..4]
+
+ # Clusters can only authenticate for their own users.
+ if remote_user_prefix != token_uuid_prefix
+ Rails.logger.warn "remote authentication rejected: claimed remote user #{remote_user_prefix} but token was issued by #{token_uuid_prefix}"
+ return nil
+ end
+
+ # Invariant: remote_user_prefix == token_uuid_prefix
+ # therefore: remote_user_prefix != Rails.configuration.ClusterID
+
+ # Add or update user and token in local database so we can
+ # validate subsequent requests faster.
+
+ user = User.find_by_uuid(remote_user['uuid'])
+
+ if !user
+ # Create a new record for this user.
+ user = User.new(uuid: remote_user['uuid'],
+ is_active: false,
+ is_admin: false,
+ email: remote_user['email'],
+ owner_uuid: system_user_uuid)
+ user.set_initial_username(requested: remote_user['username'])
+ end
+
+ # Sync user record.
+ if remote_user_prefix == Rails.configuration.Login.LoginCluster
+ # Remote cluster controls our user database, set is_active if
+ # remote is active. If remote is not active, user will be
+ # unsetup (see below).
+ user.is_active = true if remote_user['is_active']
+ user.is_admin = remote_user['is_admin']
+ else
+ if Rails.configuration.Users.NewUsersAreActive ||
+ Rails.configuration.RemoteClusters[remote_user_prefix].andand["ActivateUsers"]
+ # Default policy is to activate users
+ user.is_active = true if remote_user['is_active']