src/cobalt/black_box_tests/threaded_web_server.py

# Copyright 2018 The Cobalt 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.
"""Contains a threaded web server used for serving testdata."""

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import logging
import os
import SimpleHTTPServer
import socket
import SocketServer
import threading


class _ThreadedTCPServer(SocketServer.ThreadingMixIn, SocketServer.TCPServer):
  pass


def MakeRequestHandlerClass(base_path):
  """RequestHandler that serves files that reside relative to base_path.

  Args:
    base_path: A path considered to be the root directory.

  Returns:
    A RequestHandler class.
  """

  class TestDataHTTPRequestHandler(SimpleHTTPServer.SimpleHTTPRequestHandler):
    """Handles HTTP requests, but changes the base directory for assets."""

    _current_working_directory = os.getcwd()
    _base_path = base_path

    def translate_path(self, path):
      """Translate the request path to the file in the testdata directory."""

      potential_path = SimpleHTTPServer.SimpleHTTPRequestHandler.translate_path(
          self, path)
      potential_path = potential_path.replace(self._current_working_directory,
                                              self._base_path)
      return potential_path

    def log_message(self, format, *args):
      logging.info(format % (args))

  return TestDataHTTPRequestHandler


class ThreadedWebServer(object):
  """A HTTP WebServer that serves requests in a separate thread."""

  def __init__(self,
               handler=MakeRequestHandlerClass(os.path.dirname(__file__)),
               binding_address=None):
    _ThreadedTCPServer.allow_reuse_address = True

    if not binding_address:
      # No specific binding address specified. Bind to any interfaces instead.
      binding_address = '0.0.0.0'
    self._server = _ThreadedTCPServer((binding_address, 0), handler)

    self._server_thread = None

    self._bound_port = self._server.server_address[1]
    self._bound_host = self._server.server_address[0]
    if self._bound_host == '0.0.0.0':
      # When listening to any interfaces, get the IPv4 address of the hostname.
      self._bound_host = socket.gethostbyname(socket.gethostname())

  def GetURL(self, file_name):
    """Given a |file_name|, return a HTTP URI that can be fetched.

    Args:
      file_name: a string containing a file_name.

    Returns:
      A string containing a HTTP URI.
    """
    return 'http://{}:{}/{}'.format(self._bound_host, self._bound_port,
                                    file_name)

  def __enter__(self):
    self._server_thread = threading.Thread(target=self._server.serve_forever)
    self._server_thread.start()
    return self

  def __exit__(self, exc_type, exc_value, traceback):
    self._server.shutdown()
    self._server.server_close()
    self._server_thread.join()