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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 adds headers to outgoing requests."""
15
16import collections
17
18import grpc
19import generic_client_interceptor
20
21
22class _ClientCallDetails(
23        collections.namedtuple(
24            '_ClientCallDetails',
25            ('method', 'timeout', 'metadata', 'credentials')),
26        grpc.ClientCallDetails):
27    pass
28
29
30def header_adder_interceptor(header, value):
31
32    def intercept_call(client_call_details, request_iterator, request_streaming,
33                       response_streaming):
34        metadata = []
35        if client_call_details.metadata is not None:
36            metadata = list(client_call_details.metadata)
37        metadata.append((
38            header,
39            value,
40        ))
41        client_call_details = _ClientCallDetails(
42            client_call_details.method, client_call_details.timeout, metadata,
43            client_call_details.credentials)
44        return client_call_details, request_iterator, None
45
46    return generic_client_interceptor.create(intercept_call)
47