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+# Copyright 2012, 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.
+"""Common functions and exceptions used by WebSocket opening handshake
+processors.
+"""
+
+from __future__ import absolute_import
+
+from mod_pywebsocket import common
+from mod_pywebsocket import http_header_util
+from mod_pywebsocket.extensions import get_extension_processor
+from mod_pywebsocket.stream import StreamOptions
+from mod_pywebsocket.stream import Stream
+from mod_pywebsocket import util
+
+from six.moves import map
+from six.moves import range
+
+# Defining aliases for values used frequently.
+_VERSION_LATEST = common.VERSION_HYBI_LATEST
+_VERSION_LATEST_STRING = str(_VERSION_LATEST)
+_SUPPORTED_VERSIONS = [
+ _VERSION_LATEST,
+]
+
+
+class AbortedByUserException(Exception):
+ """Exception for aborting a connection intentionally.
+
+ If this exception is raised in do_extra_handshake handler, the connection
+ will be abandoned. No other WebSocket or HTTP(S) handler will be invoked.
+
+ If this exception is raised in transfer_data_handler, the connection will
+ be closed without closing handshake. No other WebSocket or HTTP(S) handler
+ will be invoked.
+ """
+
+ pass
+
+
+class HandshakeException(Exception):
+ """This exception will be raised when an error occurred while processing
+ WebSocket initial handshake.
+ """
+ def __init__(self, name, status=None):
+ super(HandshakeException, self).__init__(name)
+ self.status = status
+
+
+class VersionException(Exception):
+ """This exception will be raised when a version of client request does not
+ match with version the server supports.
+ """
+ def __init__(self, name, supported_versions=''):
+ """Construct an instance.
+
+ Args:
+ supported_version: a str object to show supported hybi versions.
+ (e.g. '13')
+ """
+ super(VersionException, self).__init__(name)
+ self.supported_versions = supported_versions
+
+
+def get_default_port(is_secure):
+ if is_secure:
+ return common.DEFAULT_WEB_SOCKET_SECURE_PORT
+ else:
+ return common.DEFAULT_WEB_SOCKET_PORT
+
+
+def validate_subprotocol(subprotocol):
+ """Validate a value in the Sec-WebSocket-Protocol field.
+
+ See the Section 4.1., 4.2.2., and 4.3. of RFC 6455.
+ """
+
+ if not subprotocol:
+ raise HandshakeException('Invalid subprotocol name: empty')
+
+ # Parameter should be encoded HTTP token.
+ state = http_header_util.ParsingState(subprotocol)
+ token = http_header_util.consume_token(state)
+ rest = http_header_util.peek(state)
+ # If |rest| is not None, |subprotocol| is not one token or invalid. If
+ # |rest| is None, |token| must not be None because |subprotocol| is
+ # concatenation of |token| and |rest| and is not None.
+ if rest is not None:
+ raise HandshakeException('Invalid non-token string in subprotocol '
+ 'name: %r' % rest)
+
+
+def parse_host_header(request):
+ fields = request.headers_in[common.HOST_HEADER].split(':', 1)
+ if len(fields) == 1:
+ return fields[0], get_default_port(request.is_https())
+ try:
+ return fields[0], int(fields[1])
+ except ValueError as e:
+ raise HandshakeException('Invalid port number format: %r' % e)
+
+
+def get_mandatory_header(request, key):
+ value = request.headers_in.get(key)
+ if value is None:
+ raise HandshakeException('Header %s is not defined' % key)
+ return value
+
+
+def validate_mandatory_header(request, key, expected_value, fail_status=None):
+ value = get_mandatory_header(request, key)
+
+ if value.lower() != expected_value.lower():
+ raise HandshakeException(
+ 'Expected %r for header %s but found %r (case-insensitive)' %
+ (expected_value, key, value),
+ status=fail_status)
+
+
+def parse_token_list(data):
+ """Parses a header value which follows 1#token and returns parsed elements
+ as a list of strings.
+
+ Leading LWSes must be trimmed.
+ """
+
+ state = http_header_util.ParsingState(data)
+
+ token_list = []
+
+ while True:
+ token = http_header_util.consume_token(state)
+ if token is not None:
+ token_list.append(token)
+
+ http_header_util.consume_lwses(state)
+
+ if http_header_util.peek(state) is None:
+ break
+
+ if not http_header_util.consume_string(state, ','):
+ raise HandshakeException('Expected a comma but found %r' %
+ http_header_util.peek(state))
+
+ http_header_util.consume_lwses(state)
+
+ if len(token_list) == 0:
+ raise HandshakeException('No valid token found')
+
+ return token_list
+
+
+class HandshakerBase(object):
+ def __init__(self, request, dispatcher):
+ self._logger = util.get_class_logger(self)
+ self._request = request
+ self._dispatcher = dispatcher
+
+ """ subclasses must implement the five following methods """
+
+ def _protocol_rfc(self):
+ """ Return the name of the RFC that the handshake class is implementing.
+ """
+
+ raise AssertionError("subclasses should implement this method")
+
+ def _transform_header(self, header):
+ """
+ :param header: header name
+
+ transform the header name if needed. For example, HTTP/2 subclass will
+ return the name of the header in lower case.
+ """
+
+ raise AssertionError("subclasses should implement this method")
+
+ def _validate_request(self):
+ """ validate that all the mandatory fields are set """
+
+ raise AssertionError("subclasses should implement this method")
+
+ def _set_accept(self):
+ """ Computes accept value based on Sec-WebSocket-Accept if needed. """
+
+ raise AssertionError("subclasses should implement this method")
+
+ def _send_handshake(self):
+ """ Prepare and send the response after it has been parsed and processed.
+ """
+
+ raise AssertionError("subclasses should implement this method")
+
+ def do_handshake(self):
+ self._request.ws_close_code = None
+ self._request.ws_close_reason = None
+
+ # Parsing.
+ self._validate_request()
+ self._request.ws_resource = self._request.uri
+ self._request.ws_version = self._check_version()
+
+ try:
+ self._get_origin()
+ self._set_protocol()
+ self._parse_extensions()
+
+ self._set_accept()
+
+ self._logger.debug('Protocol version is ' + self._protocol_rfc())
+
+ # Setup extension processors.
+ self._request.ws_extension_processors = self._get_extension_processors_requested(
+ )
+
+ # List of extra headers. The extra handshake handler may add header
+ # data as name/value pairs to this list and pywebsocket appends
+ # them to the WebSocket handshake.
+ self._request.extra_headers = []
+
+ # Extra handshake handler may modify/remove processors.
+ self._dispatcher.do_extra_handshake(self._request)
+
+ stream_options = StreamOptions()
+ self._process_extensions(stream_options)
+
+ self._request.ws_stream = Stream(self._request, stream_options)
+
+ if self._request.ws_requested_protocols is not None:
+ if self._request.ws_protocol is None:
+ raise HandshakeException(
+ 'do_extra_handshake must choose one subprotocol from '
+ 'ws_requested_protocols and set it to ws_protocol')
+ validate_subprotocol(self._request.ws_protocol)
+
+ self._logger.debug('Subprotocol accepted: %r',
+ self._request.ws_protocol)
+ else:
+ if self._request.ws_protocol is not None:
+ raise HandshakeException(
+ 'ws_protocol must be None when the client didn\'t '
+ 'request any subprotocol')
+
+ self._send_handshake()
+ except HandshakeException as e:
+ if not e.status:
+ # Fallback to 400 bad request by default.
+ e.status = common.HTTP_STATUS_BAD_REQUEST
+ raise e
+
+ def _check_version(self):
+ sec_websocket_version_header = self._transform_header(
+ common.SEC_WEBSOCKET_VERSION_HEADER)
+ version = get_mandatory_header(self._request,
+ sec_websocket_version_header)
+ if version == _VERSION_LATEST_STRING:
+ return _VERSION_LATEST
+
+ if version.find(',') >= 0:
+ raise HandshakeException(
+ 'Multiple versions (%r) are not allowed for header %s' %
+ (version, sec_websocket_version_header),
+ status=common.HTTP_STATUS_BAD_REQUEST)
+ raise VersionException('Unsupported version %r for header %s' %
+ (version, sec_websocket_version_header),
+ supported_versions=', '.join(
+ map(str, _SUPPORTED_VERSIONS)))
+
+ def _get_origin(self):
+ origin_header = self._transform_header(common.ORIGIN_HEADER)
+ origin = self._request.headers_in.get(origin_header)
+ if origin is None:
+ self._logger.debug('Client request does not have origin header')
+ self._request.ws_origin = origin
+
+ def _set_protocol(self):
+ self._request.ws_protocol = None
+ # MOZILLA
+ self._request.sts = None
+ # /MOZILLA
+
+ sec_websocket_protocol_header = self._transform_header(
+ common.SEC_WEBSOCKET_PROTOCOL_HEADER)
+ protocol_header = self._request.headers_in.get(
+ sec_websocket_protocol_header)
+
+ if protocol_header is None:
+ self._request.ws_requested_protocols = None
+ return
+
+ self._request.ws_requested_protocols = parse_token_list(
+ protocol_header)
+ self._logger.debug('Subprotocols requested: %r',
+ self._request.ws_requested_protocols)
+
+ def _parse_extensions(self):
+ sec_websocket_extensions_header = self._transform_header(
+ common.SEC_WEBSOCKET_EXTENSIONS_HEADER)
+ extensions_header = self._request.headers_in.get(
+ sec_websocket_extensions_header)
+ if not extensions_header:
+ self._request.ws_requested_extensions = None
+ return
+
+ try:
+ self._request.ws_requested_extensions = common.parse_extensions(
+ extensions_header)
+ except common.ExtensionParsingException as e:
+ raise HandshakeException(
+ 'Failed to parse sec-websocket-extensions header: %r' % e)
+
+ self._logger.debug(
+ 'Extensions requested: %r',
+ list(
+ map(common.ExtensionParameter.name,
+ self._request.ws_requested_extensions)))
+
+ def _get_extension_processors_requested(self):
+ processors = []
+ if self._request.ws_requested_extensions is not None:
+ for extension_request in self._request.ws_requested_extensions:
+ processor = get_extension_processor(extension_request)
+ # Unknown extension requests are just ignored.
+ if processor is not None:
+ processors.append(processor)
+ return processors
+
+ def _process_extensions(self, stream_options):
+ processors = [
+ processor for processor in self._request.ws_extension_processors
+ if processor is not None
+ ]
+
+ # Ask each processor if there are extensions on the request which
+ # cannot co-exist. When processor decided other processors cannot
+ # co-exist with it, the processor marks them (or itself) as
+ # "inactive". The first extension processor has the right to
+ # make the final call.
+ for processor in reversed(processors):
+ if processor.is_active():
+ processor.check_consistency_with_other_processors(processors)
+ processors = [
+ processor for processor in processors if processor.is_active()
+ ]
+
+ accepted_extensions = []
+
+ for index, processor in enumerate(processors):
+ if not processor.is_active():
+ continue
+
+ extension_response = processor.get_extension_response()
+ if extension_response is None:
+ # Rejected.
+ continue
+
+ accepted_extensions.append(extension_response)
+
+ processor.setup_stream_options(stream_options)
+
+ # Inactivate all of the following compression extensions.
+ for j in range(index + 1, len(processors)):
+ processors[j].set_active(False)
+
+ if len(accepted_extensions) > 0:
+ self._request.ws_extensions = accepted_extensions
+ self._logger.debug(
+ 'Extensions accepted: %r',
+ list(map(common.ExtensionParameter.name, accepted_extensions)))
+ else:
+ self._request.ws_extensions = None
+
+
+# vi:sts=4 sw=4 et