# 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 mod_pywebsocket import common
from mod_pywebsocket import http_header_util
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. '8, 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, hixie):
"""Validate a value in subprotocol fields such as WebSocket-Protocol,
Sec-WebSocket-Protocol.
See
- RFC 6455: Section 4.1., 4.2.2., and 4.3.
- HyBi 00: Section 4.1. Opening handshake
- Hixie 75: Section 4.1. Handshake
"""
if not subprotocol:
raise HandshakeException('Invalid subprotocol name: empty')
if hixie:
# Parameter should be in the range U+0020 to U+007E.
for c in subprotocol:
if not 0x20 <= ord(c) <= 0x7e:
raise HandshakeException(
'Illegal character in subprotocol name: %r' % c)
else:
# 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['Host'].split(':', 1)
if len(fields) == 1:
return fields[0], get_default_port(request.is_https())
try:
return fields[0], int(fields[1])
except ValueError, e:
raise HandshakeException('Invalid port number format: %r' % e)
def format_header(name, value):
return '%s: %s\r\n' % (name, value)
def build_location(request):
"""Build WebSocket location for request."""
location_parts = []
if request.is_https():
location_parts.append(common.WEB_SOCKET_SECURE_SCHEME)
else:
location_parts.append(common.WEB_SOCKET_SCHEME)
location_parts.append('://')
host, port = parse_host_header(request)
connection_port = request.connection.local_addr[1]
if port != connection_port:
raise HandshakeException('Header/connection port mismatch: %d/%d' %
(port, connection_port))
location_parts.append(host)
if (port != get_default_port(request.is_https())):
location_parts.append(':')
location_parts.append(str(port))
location_parts.append(request.uri)
return ''.join(location_parts)
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 check_request_line(request):
# 5.1 1. The three character UTF-8 string "GET".
# 5.1 2. A UTF-8-encoded U+0020 SPACE character (0x20 byte).
if request.method != 'GET':
raise HandshakeException('Method is not GET')
def check_header_lines(request, mandatory_headers):
check_request_line(request)
# The expected field names, and the meaning of their corresponding
# values, are as follows.
# |Upgrade| and |Connection|
for key, expected_value in mandatory_headers:
validate_mandatory_header(request, key, expected_value)
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
# vi:sts=4 sw=4 et