# Copyright 2009, Google Inc. # All rights reserved. # # Redistribution and use in source and binary forms, with or without # modification, are permitted provided that the following conditions are # met: # # * Redistributions of source code must retain the above copyright # notice, this list of conditions and the following disclaimer. # * Redistributions in binary form must reproduce the above # copyright notice, this list of conditions and the following disclaimer # in the documentation and/or other materials provided with the # distribution. # * Neither the name of Google Inc. nor the names of its # contributors may be used to endorse or promote products derived from # this software without specific prior written permission. # # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. """Dispatch Web Socket request. """ import os import re from mod_pywebsocket import msgutil from mod_pywebsocket import util _SOURCE_PATH_PATTERN = re.compile(r'(?i)_wsh\.py$') _SOURCE_SUFFIX = '_wsh.py' _DO_EXTRA_HANDSHAKE_HANDLER_NAME = 'web_socket_do_extra_handshake' _TRANSFER_DATA_HANDLER_NAME = 'web_socket_transfer_data' class DispatchError(Exception): """Exception in dispatching Web Socket request.""" pass def _normalize_path(path): """Normalize path. Args: path: the path to normalize. Path is converted to the absolute path. The input path can use either '\\' or '/' as the separator. The normalized path always uses '/' regardless of the platform. """ path = path.replace('\\', os.path.sep) #path = os.path.realpath(path) path = path.replace('\\', '/') return path def _path_to_resource_converter(base_dir): base_dir = _normalize_path(base_dir) base_len = len(base_dir) suffix_len = len(_SOURCE_SUFFIX) def converter(path): if not path.endswith(_SOURCE_SUFFIX): return None path = _normalize_path(path) if not path.startswith(base_dir): return None return path[base_len:-suffix_len] return converter def _source_file_paths(directory): """Yield Web Socket Handler source file names in the given directory.""" for root, unused_dirs, files in os.walk(directory): for base in files: path = os.path.join(root, base) if _SOURCE_PATH_PATTERN.search(path): yield path def _source(source_str): """Source a handler definition string.""" global_dic = {} try: exec source_str in global_dic except Exception: raise DispatchError('Error in sourcing handler:' + util.get_stack_trace()) return (_extract_handler(global_dic, _DO_EXTRA_HANDSHAKE_HANDLER_NAME), _extract_handler(global_dic, _TRANSFER_DATA_HANDLER_NAME)) def _extract_handler(dic, name): if name not in dic: raise DispatchError('%s is not defined.' % name) handler = dic[name] if not callable(handler): raise DispatchError('%s is not callable.' % name) return handler class Dispatcher(object): """Dispatches Web Socket requests. This class maintains a map from resource name to handlers. """ def __init__(self, root_dir, scan_dir=None): """Construct an instance. Args: root_dir: The directory where handler definition files are placed. scan_dir: The directory where handler definition files are searched. scan_dir must be a directory under root_dir, including root_dir itself. If scan_dir is None, root_dir is used as scan_dir. scan_dir can be useful in saving scan time when root_dir contains many subdirectories. """ self._handlers = {} self._source_warnings = [] if scan_dir is None: scan_dir = root_dir if not os.path.realpath(scan_dir).startswith( os.path.realpath(root_dir)): raise DispatchError('scan_dir:%s must be a directory under ' 'root_dir:%s.' % (scan_dir, root_dir)) self._source_files_in_dir(root_dir, scan_dir) def add_resource_path_alias(self, alias_resource_path, existing_resource_path): """Add resource path alias. Once added, request to alias_resource_path would be handled by handler registered for existing_resource_path. Args: alias_resource_path: alias resource path existing_resource_path: existing resource path """ try: handler = self._handlers[existing_resource_path] self._handlers[alias_resource_path] = handler except KeyError: raise DispatchError('No handler for: %r' % existing_resource_path) def source_warnings(self): """Return warnings in sourcing handlers.""" return self._source_warnings def do_extra_handshake(self, request): """Do extra checking in Web Socket handshake. Select a handler based on request.uri and call its web_socket_do_extra_handshake function. Args: request: mod_python request. """ do_extra_handshake_, unused_transfer_data = self._handler(request) try: do_extra_handshake_(request) except Exception, e: util.prepend_message_to_exception( '%s raised exception for %s: ' % ( _DO_EXTRA_HANDSHAKE_HANDLER_NAME, request.ws_resource), e) raise def transfer_data(self, request): """Let a handler transfer_data with a Web Socket client. Select a handler based on request.ws_resource and call its web_socket_transfer_data function. Args: request: mod_python request. """ unused_do_extra_handshake, transfer_data_ = self._handler(request) try: try: request.client_terminated = False request.server_terminated = False transfer_data_(request) except msgutil.ConnectionTerminatedException, e: util.prepend_message_to_exception( 'client initiated closing handshake for %s: ' % ( request.ws_resource), e) raise except Exception, e: print 'exception: %s' % type(e) util.prepend_message_to_exception( '%s raised exception for %s: ' % ( _TRANSFER_DATA_HANDLER_NAME, request.ws_resource), e) raise finally: msgutil.close_connection(request) def _handler(self, request): try: ws_resource_path = request.ws_resource.split('?', 1)[0] return self._handlers[ws_resource_path] except KeyError: raise DispatchError('No handler for: %r' % request.ws_resource) def _source_files_in_dir(self, root_dir, scan_dir): """Source all the handler source files in the scan_dir directory. The resource path is determined relative to root_dir. """ to_resource = _path_to_resource_converter(root_dir) for path in _source_file_paths(scan_dir): try: handlers = _source(open(path).read()) except DispatchError, e: self._source_warnings.append('%s: %s' % (path, e)) continue self._handlers[to_resource(path)] = handlers # vi:sts=4 sw=4 et