1# Copyright 2016 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
15import logging
16
17import http2_base_server
18import messages_pb2
19
20# Set the number of padding bytes per data frame to be very large
21# relative to the number of data bytes for each data frame sent.
22_LARGE_PADDING_LENGTH = 255
23_SMALL_READ_CHUNK_SIZE = 5
24
25
26class TestDataFramePadding(object):
27    """
28    In response to an incoming request, this test sends headers, followed by
29    data, followed by a reset stream frame. Client asserts that the RPC failed.
30    Client needs to deliver the complete message to the application layer.
31  """
32
33    def __init__(self, use_padding=True):
34        self._base_server = http2_base_server.H2ProtocolBaseServer()
35        self._base_server._handlers['DataReceived'] = self.on_data_received
36        self._base_server._handlers['WindowUpdated'] = self.on_window_update
37        self._base_server._handlers[
38            'RequestReceived'] = self.on_request_received
39
40        # _total_updates maps stream ids to total flow control updates received
41        self._total_updates = {}
42        # zero window updates so far for connection window (stream id '0')
43        self._total_updates[0] = 0
44        self._read_chunk_size = _SMALL_READ_CHUNK_SIZE
45
46        if use_padding:
47            self._pad_length = _LARGE_PADDING_LENGTH
48        else:
49            self._pad_length = None
50
51    def get_base_server(self):
52        return self._base_server
53
54    def on_data_received(self, event):
55        logging.info('on data received. Stream id: %d. Data length: %d' %
56                     (event.stream_id, len(event.data)))
57        self._base_server.on_data_received_default(event)
58        if len(event.data) == 0:
59            return
60        sr = self._base_server.parse_received_data(event.stream_id)
61        stream_bytes = ''
62        # Check if full grpc msg has been read into the recv buffer yet
63        if sr:
64            response_data = self._base_server.default_response_data(
65                sr.response_size)
66            logging.info('Stream id: %d. total resp size: %d' %
67                         (event.stream_id, len(response_data)))
68            # Begin sending the response. Add ``self._pad_length`` padding to each
69            # data frame and split the whole message into data frames each carrying
70            # only self._read_chunk_size of data.
71            # The purpose is to have the majority of the data frame response bytes
72            # be padding bytes, since ``self._pad_length`` >> ``self._read_chunk_size``.
73            self._base_server.setup_send(response_data,
74                                         event.stream_id,
75                                         pad_length=self._pad_length,
76                                         read_chunk_size=self._read_chunk_size)
77
78    def on_request_received(self, event):
79        self._base_server.on_request_received_default(event)
80        logging.info('on request received. Stream id: %s.' % event.stream_id)
81        self._total_updates[event.stream_id] = 0
82
83    # Log debug info and try to resume sending on all currently active streams.
84    def on_window_update(self, event):
85        logging.info('on window update. Stream id: %s. Delta: %s' %
86                     (event.stream_id, event.delta))
87        self._total_updates[event.stream_id] += event.delta
88        total = self._total_updates[event.stream_id]
89        logging.info('... - total updates for stream %d : %d' %
90                     (event.stream_id, total))
91        self._base_server.on_window_update_default(
92            event,
93            pad_length=self._pad_length,
94            read_chunk_size=self._read_chunk_size)
95