1# Copyright 2017 gRPC authors.
2#
3# Licensed under the Apache License, Version 2.0 (the "License");
4# you may not use this file except in compliance with the License.
5# You may obtain a copy of the License at
6#
7#     http://www.apache.org/licenses/LICENSE-2.0
8#
9# Unless required by applicable law or agreed to in writing, software
10# distributed under the License is distributed on an "AS IS" BASIS,
11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12# See the License for the specific language governing permissions and
13# limitations under the License.
14"""Interceptor that ensures a specific header is present."""
15
16import grpc
17
18
19def _unary_unary_rpc_terminator(code, details):
20    def terminate(ignored_request, context):
21        context.abort(code, details)
22
23    return grpc.unary_unary_rpc_method_handler(terminate)
24
25
26class RequestHeaderValidatorInterceptor(grpc.ServerInterceptor):
27    def __init__(self, header, value, code, details):
28        self._header = header
29        self._value = value
30        self._terminator = _unary_unary_rpc_terminator(code, details)
31
32    def intercept_service(self, continuation, handler_call_details):
33        if (
34            self._header,
35            self._value,
36        ) in handler_call_details.invocation_metadata:
37            return continuation(handler_call_details)
38        else:
39            return self._terminator
40