1 # Copyright 2012, Google Inc. 2 # All rights reserved. 3 # 4 # Redistribution and use in source and binary forms, with or without 5 # modification, are permitted provided that the following conditions are 6 # met: 7 # 8 # * Redistributions of source code must retain the above copyright 9 # notice, this list of conditions and the following disclaimer. 10 # * Redistributions in binary form must reproduce the above 11 # copyright notice, this list of conditions and the following disclaimer 12 # in the documentation and/or other materials provided with the 13 # distribution. 14 # * Neither the name of Google Inc. nor the names of its 15 # contributors may be used to endorse or promote products derived from 16 # this software without specific prior written permission. 17 # 18 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 19 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 20 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 21 # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 22 # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 23 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 24 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 28 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 30 31 """Common functions and exceptions used by WebSocket opening handshake 32 processors. 33 """ 34 35 36 from mod_pywebsocket import common 37 from mod_pywebsocket import http_header_util 38 39 40 class AbortedByUserException(Exception): 41 """Exception for aborting a connection intentionally. 42 43 If this exception is raised in do_extra_handshake handler, the connection 44 will be abandoned. No other WebSocket or HTTP(S) handler will be invoked. 45 46 If this exception is raised in transfer_data_handler, the connection will 47 be closed without closing handshake. No other WebSocket or HTTP(S) handler 48 will be invoked. 49 """ 50 51 pass 52 53 54 class HandshakeException(Exception): 55 """This exception will be raised when an error occurred while processing 56 WebSocket initial handshake. 57 """ 58 59 def __init__(self, name, status=None): 60 super(HandshakeException, self).__init__(name) 61 self.status = status 62 63 64 class VersionException(Exception): 65 """This exception will be raised when a version of client request does not 66 match with version the server supports. 67 """ 68 69 def __init__(self, name, supported_versions=''): 70 """Construct an instance. 71 72 Args: 73 supported_version: a str object to show supported hybi versions. 74 (e.g. '8, 13') 75 """ 76 super(VersionException, self).__init__(name) 77 self.supported_versions = supported_versions 78 79 80 def get_default_port(is_secure): 81 if is_secure: 82 return common.DEFAULT_WEB_SOCKET_SECURE_PORT 83 else: 84 return common.DEFAULT_WEB_SOCKET_PORT 85 86 87 def validate_subprotocol(subprotocol): 88 """Validate a value in the Sec-WebSocket-Protocol field. 89 90 See the Section 4.1., 4.2.2., and 4.3. of RFC 6455. 91 """ 92 93 if not subprotocol: 94 raise HandshakeException('Invalid subprotocol name: empty') 95 96 # Parameter should be encoded HTTP token. 97 state = http_header_util.ParsingState(subprotocol) 98 token = http_header_util.consume_token(state) 99 rest = http_header_util.peek(state) 100 # If |rest| is not None, |subprotocol| is not one token or invalid. If 101 # |rest| is None, |token| must not be None because |subprotocol| is 102 # concatenation of |token| and |rest| and is not None. 103 if rest is not None: 104 raise HandshakeException('Invalid non-token string in subprotocol ' 105 'name: %r' % rest) 106 107 108 def parse_host_header(request): 109 fields = request.headers_in[common.HOST_HEADER].split(':', 1) 110 if len(fields) == 1: 111 return fields[0], get_default_port(request.is_https()) 112 try: 113 return fields[0], int(fields[1]) 114 except ValueError, e: 115 raise HandshakeException('Invalid port number format: %r' % e) 116 117 118 def format_header(name, value): 119 return '%s: %s\r\n' % (name, value) 120 121 122 def get_mandatory_header(request, key): 123 value = request.headers_in.get(key) 124 if value is None: 125 raise HandshakeException('Header %s is not defined' % key) 126 return value 127 128 129 def validate_mandatory_header(request, key, expected_value, fail_status=None): 130 value = get_mandatory_header(request, key) 131 132 if value.lower() != expected_value.lower(): 133 raise HandshakeException( 134 'Expected %r for header %s but found %r (case-insensitive)' % 135 (expected_value, key, value), status=fail_status) 136 137 138 def check_request_line(request): 139 # 5.1 1. The three character UTF-8 string "GET". 140 # 5.1 2. A UTF-8-encoded U+0020 SPACE character (0x20 byte). 141 if request.method != 'GET': 142 raise HandshakeException('Method is not GET: %r' % request.method) 143 144 if request.protocol != 'HTTP/1.1': 145 raise HandshakeException('Version is not HTTP/1.1: %r' % 146 request.protocol) 147 148 149 def parse_token_list(data): 150 """Parses a header value which follows 1#token and returns parsed elements 151 as a list of strings. 152 153 Leading LWSes must be trimmed. 154 """ 155 156 state = http_header_util.ParsingState(data) 157 158 token_list = [] 159 160 while True: 161 token = http_header_util.consume_token(state) 162 if token is not None: 163 token_list.append(token) 164 165 http_header_util.consume_lwses(state) 166 167 if http_header_util.peek(state) is None: 168 break 169 170 if not http_header_util.consume_string(state, ','): 171 raise HandshakeException( 172 'Expected a comma but found %r' % http_header_util.peek(state)) 173 174 http_header_util.consume_lwses(state) 175 176 if len(token_list) == 0: 177 raise HandshakeException('No valid token found') 178 179 return token_list 180 181 182 # vi:sts=4 sw=4 et 183
