forked from mirrors/gecko-dev
393 lines
14 KiB
Python
393 lines
14 KiB
Python
# Copyright 2012, Google Inc.
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are
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# met:
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#
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# * Redistributions of source code must retain the above copyright
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# notice, this list of conditions and the following disclaimer.
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# * Redistributions in binary form must reproduce the above
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# copyright notice, this list of conditions and the following disclaimer
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# in the documentation and/or other materials provided with the
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# distribution.
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# * Neither the name of Google Inc. nor the names of its
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# contributors may be used to endorse or promote products derived from
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# this software without specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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"""Dispatch WebSocket request.
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"""
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import logging
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import os
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import re
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from mod_pywebsocket import common
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from mod_pywebsocket import handshake
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from mod_pywebsocket import msgutil
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from mod_pywebsocket import mux
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from mod_pywebsocket import stream
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from mod_pywebsocket import util
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_SOURCE_PATH_PATTERN = re.compile(r'(?i)_wsh\.py$')
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_SOURCE_SUFFIX = '_wsh.py'
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_DO_EXTRA_HANDSHAKE_HANDLER_NAME = 'web_socket_do_extra_handshake'
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_TRANSFER_DATA_HANDLER_NAME = 'web_socket_transfer_data'
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_PASSIVE_CLOSING_HANDSHAKE_HANDLER_NAME = (
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'web_socket_passive_closing_handshake')
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class DispatchException(Exception):
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"""Exception in dispatching WebSocket request."""
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def __init__(self, name, status=common.HTTP_STATUS_NOT_FOUND):
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super(DispatchException, self).__init__(name)
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self.status = status
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def _default_passive_closing_handshake_handler(request):
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"""Default web_socket_passive_closing_handshake handler."""
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return common.STATUS_NORMAL_CLOSURE, ''
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def _normalize_path(path):
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"""Normalize path.
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Args:
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path: the path to normalize.
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Path is converted to the absolute path.
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The input path can use either '\\' or '/' as the separator.
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The normalized path always uses '/' regardless of the platform.
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"""
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path = path.replace('\\', os.path.sep)
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path = os.path.realpath(path)
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path = path.replace('\\', '/')
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return path
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def _create_path_to_resource_converter(base_dir):
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"""Returns a function that converts the path of a WebSocket handler source
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file to a resource string by removing the path to the base directory from
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its head, removing _SOURCE_SUFFIX from its tail, and replacing path
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separators in it with '/'.
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Args:
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base_dir: the path to the base directory.
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"""
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base_dir = _normalize_path(base_dir)
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base_len = len(base_dir)
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suffix_len = len(_SOURCE_SUFFIX)
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def converter(path):
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if not path.endswith(_SOURCE_SUFFIX):
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return None
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# _normalize_path must not be used because resolving symlink breaks
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# following path check.
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path = path.replace('\\', '/')
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if not path.startswith(base_dir):
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return None
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return path[base_len:-suffix_len]
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return converter
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def _enumerate_handler_file_paths(directory):
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"""Returns a generator that enumerates WebSocket Handler source file names
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in the given directory.
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"""
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for root, unused_dirs, files in os.walk(directory):
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for base in files:
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path = os.path.join(root, base)
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if _SOURCE_PATH_PATTERN.search(path):
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yield path
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class _HandlerSuite(object):
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"""A handler suite holder class."""
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def __init__(self, do_extra_handshake, transfer_data,
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passive_closing_handshake):
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self.do_extra_handshake = do_extra_handshake
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self.transfer_data = transfer_data
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self.passive_closing_handshake = passive_closing_handshake
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def _source_handler_file(handler_definition):
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"""Source a handler definition string.
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Args:
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handler_definition: a string containing Python statements that define
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handler functions.
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"""
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global_dic = {}
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try:
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exec handler_definition in global_dic
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except Exception:
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raise DispatchException('Error in sourcing handler:' +
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util.get_stack_trace())
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passive_closing_handshake_handler = None
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try:
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passive_closing_handshake_handler = _extract_handler(
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global_dic, _PASSIVE_CLOSING_HANDSHAKE_HANDLER_NAME)
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except Exception:
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passive_closing_handshake_handler = (
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_default_passive_closing_handshake_handler)
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return _HandlerSuite(
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_extract_handler(global_dic, _DO_EXTRA_HANDSHAKE_HANDLER_NAME),
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_extract_handler(global_dic, _TRANSFER_DATA_HANDLER_NAME),
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passive_closing_handshake_handler)
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def _extract_handler(dic, name):
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"""Extracts a callable with the specified name from the given dictionary
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dic.
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"""
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if name not in dic:
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raise DispatchException('%s is not defined.' % name)
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handler = dic[name]
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if not callable(handler):
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raise DispatchException('%s is not callable.' % name)
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return handler
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class Dispatcher(object):
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"""Dispatches WebSocket requests.
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This class maintains a map from resource name to handlers.
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"""
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def __init__(
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self, root_dir, scan_dir=None,
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allow_handlers_outside_root_dir=True):
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"""Construct an instance.
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Args:
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root_dir: The directory where handler definition files are
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placed.
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scan_dir: The directory where handler definition files are
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searched. scan_dir must be a directory under root_dir,
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including root_dir itself. If scan_dir is None,
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root_dir is used as scan_dir. scan_dir can be useful
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in saving scan time when root_dir contains many
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subdirectories.
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allow_handlers_outside_root_dir: Scans handler files even if their
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canonical path is not under root_dir.
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"""
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self._logger = util.get_class_logger(self)
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self._handler_suite_map = {}
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self._source_warnings = []
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if scan_dir is None:
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scan_dir = root_dir
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if not os.path.realpath(scan_dir).startswith(
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os.path.realpath(root_dir)):
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raise DispatchException('scan_dir:%s must be a directory under '
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'root_dir:%s.' % (scan_dir, root_dir))
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self._source_handler_files_in_dir(
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root_dir, scan_dir, allow_handlers_outside_root_dir)
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def add_resource_path_alias(self,
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alias_resource_path, existing_resource_path):
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"""Add resource path alias.
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Once added, request to alias_resource_path would be handled by
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handler registered for existing_resource_path.
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Args:
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alias_resource_path: alias resource path
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existing_resource_path: existing resource path
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"""
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try:
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handler_suite = self._handler_suite_map[existing_resource_path]
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self._handler_suite_map[alias_resource_path] = handler_suite
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except KeyError:
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raise DispatchException('No handler for: %r' %
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existing_resource_path)
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def source_warnings(self):
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"""Return warnings in sourcing handlers."""
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return self._source_warnings
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def do_extra_handshake(self, request):
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"""Do extra checking in WebSocket handshake.
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Select a handler based on request.uri and call its
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web_socket_do_extra_handshake function.
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Args:
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request: mod_python request.
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Raises:
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DispatchException: when handler was not found
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AbortedByUserException: when user handler abort connection
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HandshakeException: when opening handshake failed
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"""
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handler_suite = self.get_handler_suite(request.ws_resource)
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if handler_suite is None:
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raise DispatchException('No handler for: %r' % request.ws_resource)
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do_extra_handshake_ = handler_suite.do_extra_handshake
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try:
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do_extra_handshake_(request)
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except handshake.AbortedByUserException, e:
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# Re-raise to tell the caller of this function to finish this
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# connection without sending any error.
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self._logger.debug('%s', util.get_stack_trace())
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raise
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except Exception, e:
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util.prepend_message_to_exception(
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'%s raised exception for %s: ' % (
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_DO_EXTRA_HANDSHAKE_HANDLER_NAME,
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request.ws_resource),
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e)
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raise handshake.HandshakeException(e, common.HTTP_STATUS_FORBIDDEN)
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def transfer_data(self, request):
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"""Let a handler transfer_data with a WebSocket client.
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Select a handler based on request.ws_resource and call its
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web_socket_transfer_data function.
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Args:
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request: mod_python request.
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Raises:
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DispatchException: when handler was not found
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AbortedByUserException: when user handler abort connection
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"""
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# TODO(tyoshino): Terminate underlying TCP connection if possible.
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try:
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if mux.use_mux(request):
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mux.start(request, self)
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else:
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handler_suite = self.get_handler_suite(request.ws_resource)
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if handler_suite is None:
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raise DispatchException('No handler for: %r' %
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request.ws_resource)
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transfer_data_ = handler_suite.transfer_data
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transfer_data_(request)
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if not request.server_terminated:
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request.ws_stream.close_connection()
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# Catch non-critical exceptions the handler didn't handle.
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except handshake.AbortedByUserException, e:
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self._logger.debug('%s', util.get_stack_trace())
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raise
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except msgutil.BadOperationException, e:
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self._logger.debug('%s', e)
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request.ws_stream.close_connection(
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common.STATUS_INTERNAL_ENDPOINT_ERROR)
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except msgutil.InvalidFrameException, e:
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# InvalidFrameException must be caught before
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# ConnectionTerminatedException that catches InvalidFrameException.
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self._logger.debug('%s', e)
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request.ws_stream.close_connection(common.STATUS_PROTOCOL_ERROR)
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except msgutil.UnsupportedFrameException, e:
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self._logger.debug('%s', e)
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request.ws_stream.close_connection(common.STATUS_UNSUPPORTED_DATA)
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except stream.InvalidUTF8Exception, e:
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self._logger.debug('%s', e)
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request.ws_stream.close_connection(
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common.STATUS_INVALID_FRAME_PAYLOAD_DATA)
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except msgutil.ConnectionTerminatedException, e:
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self._logger.debug('%s', e)
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except Exception, e:
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# Any other exceptions are forwarded to the caller of this
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# function.
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util.prepend_message_to_exception(
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'%s raised exception for %s: ' % (
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_TRANSFER_DATA_HANDLER_NAME, request.ws_resource),
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e)
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raise
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def passive_closing_handshake(self, request):
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"""Prepare code and reason for responding client initiated closing
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handshake.
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"""
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handler_suite = self.get_handler_suite(request.ws_resource)
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if handler_suite is None:
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return _default_passive_closing_handshake_handler(request)
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return handler_suite.passive_closing_handshake(request)
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def get_handler_suite(self, resource):
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"""Retrieves two handlers (one for extra handshake processing, and one
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for data transfer) for the given request as a HandlerSuite object.
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"""
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fragment = None
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if '#' in resource:
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resource, fragment = resource.split('#', 1)
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if '?' in resource:
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resource = resource.split('?', 1)[0]
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handler_suite = self._handler_suite_map.get(resource)
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if handler_suite and fragment:
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raise DispatchException('Fragment identifiers MUST NOT be used on '
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'WebSocket URIs',
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common.HTTP_STATUS_BAD_REQUEST)
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return handler_suite
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def _source_handler_files_in_dir(
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self, root_dir, scan_dir, allow_handlers_outside_root_dir):
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"""Source all the handler source files in the scan_dir directory.
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The resource path is determined relative to root_dir.
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"""
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# We build a map from resource to handler code assuming that there's
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# only one path from root_dir to scan_dir and it can be obtained by
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# comparing realpath of them.
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# Here we cannot use abspath. See
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# https://bugs.webkit.org/show_bug.cgi?id=31603
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convert = _create_path_to_resource_converter(root_dir)
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scan_realpath = os.path.realpath(scan_dir)
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root_realpath = os.path.realpath(root_dir)
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for path in _enumerate_handler_file_paths(scan_realpath):
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if (not allow_handlers_outside_root_dir and
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(not os.path.realpath(path).startswith(root_realpath))):
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self._logger.debug(
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'Canonical path of %s is not under root directory' %
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path)
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continue
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try:
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handler_suite = _source_handler_file(open(path).read())
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except DispatchException, e:
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self._source_warnings.append('%s: %s' % (path, e))
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continue
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resource = convert(path)
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if resource is None:
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self._logger.debug(
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'Path to resource conversion on %s failed' % path)
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else:
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self._handler_suite_map[convert(path)] = handler_suite
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# vi:sts=4 sw=4 et
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