protocol.py
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protocol.py
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	# Copyright (C) 2008-2012 AG Projects. See LICENSE for details

	import random
	import re

	from application.system import host as host_module
	from collections import deque, namedtuple
	from gnutls.interfaces.twisted import X509Credentials
	from twisted.internet.protocol import connectionDone
	from twisted.protocols.basic import LineReceiver

	from msrplib import MSRPError


	class ParsingError(MSRPError):
	pass


	class HeaderParsingError(ParsingError):
	def __init__(self, header, reason):
	self.header = header
	ParsingError.__init__(self, 'Error parsing {} header: {}'.format(header, reason))


	# Header value data types (for decoded values)
	#

	ByteRange = namedtuple('ByteRange', ['start', 'end', 'total'])
	Status = namedtuple('Status', ['code', 'comment'])
	ContentDisposition = namedtuple('ContentDisposition', ['disposition', 'parameters'])


	# Header value types (describe how to encode/decode the value)
	#

	class SimpleHeaderType(object):
	data_type = object

	@staticmethod
	def decode(encoded):
	return encoded

	@staticmethod
	def encode(decoded):
	return decoded


	class UTF8HeaderType(object):
	data_type = unicode

	@staticmethod
	def decode(encoded):
	return encoded.decode('utf-8')

	@staticmethod
	def encode(decoded):
	return decoded.encode('utf-8')


	class URIHeaderType(object):
	data_type = deque

	@staticmethod
	def decode(encoded):
	return deque(URI.parse(uri) for uri in encoded.split(' '))

	@staticmethod
	def encode(decoded):
	return ' '.join(str(uri) for uri in decoded)


	class IntegerHeaderType(object):
	data_type = int

	@staticmethod
	def decode(encoded):
	return int(encoded)

	@staticmethod
	def encode(decoded):
	return str(decoded)


	class LimitedChoiceHeaderType(SimpleHeaderType):
	allowed_values = frozenset()

	@classmethod
	def decode(cls, encoded):
	if encoded not in cls.allowed_values:
	raise ValueError('Invalid value: {!r}'.format(encoded))
	return encoded


	class SuccessReportHeaderType(LimitedChoiceHeaderType):
	allowed_values = frozenset({'yes', 'no'})


	class FailureReportHeaderType(LimitedChoiceHeaderType):
	allowed_values = frozenset({'yes', 'no', 'partial'})


	class ByteRangeHeaderType(object):
	data_type = ByteRange

	regex = re.compile(r'(?P<start>\d+)-(?P<end>\\|\d+)/(?P<total>\\|\d+)')

	@classmethod
	def decode(cls, encoded):
	match = cls.regex.match(encoded)
	if match is None:
	raise ValueError('Invalid byte range value: {!r}'.format(encoded))
	start, end, total = match.groups()
	start = int(start)
	end = int(end) if end != '*' else None
	total = int(total) if total != '*' else None
	return ByteRange(start, end, total)

	@staticmethod
	def encode(decoded):
	start, end, total = decoded
	return '{}-{}/{}'.format(start, '' if end is None else end, '' if total is None else total)


	class StatusHeaderType(object):
	data_type = Status

	@staticmethod
	def decode(encoded):
	namespace, sep, rest = encoded.partition(' ')
	if namespace != '000' or sep != ' ':
	raise ValueError('Invalid status value: {!r}'.format(encoded))
	code, _, comment = rest.partition(' ')
	if not code.isdigit() or len(code) != 3:
	raise ValueError('Invalid status code: {!r}'.format(code))
	return Status(int(code), comment or None)

	@staticmethod
	def encode(decoded):
	code, comment = decoded
	if comment is None:
	return '000 {:03d}'.format(code)
	else:
	return '000 {:03d} {}'.format(code, comment)


	class ContentDispositionHeaderType(object):
	data_type = ContentDisposition

	regex = re.compile(r'(\w+)=("[^"]+"\|[^";]+)')

	@classmethod
	def decode(cls, encoded):
	disposition, _, parameters = encoded.partition(';')
	if not disposition:
	raise ValueError('Invalid content disposition: {!r}'.format(encoded))
	return ContentDisposition(disposition, {name: value.strip('"') for name, value in cls.regex.findall(parameters)})

	@staticmethod
	def encode(decoded):
	disposition, parameters = decoded
	return '; '.join([disposition] + ['{}="{}"'.format(name, value) for name, value in parameters.iteritems()])


	class ParameterListHeaderType(object):
	data_type = dict

	regex = re.compile(r'(\w+)=("[^"]+"\|[^",]+)')

	@classmethod
	def decode(cls, encoded):
	return {name: value.strip('"') for name, value in cls.regex.findall(encoded)}

	@staticmethod
	def encode(decoded):
	return ', '.join('{}="{}"'.format(name, value) for name, value in decoded.iteritems())


	class DigestHeaderType(ParameterListHeaderType):
	@classmethod
	def decode(cls, encoded):
	algorithm, sep, parameters = encoded.partition(' ')
	if algorithm != 'Digest' or sep != ' ':
	raise ValueError('Invalid Digest header value')
	return super(DigestHeaderType, cls).decode(parameters)

	@staticmethod
	def encode(decoded):
	return 'Digest ' + super(DigestHeaderType, DigestHeaderType).encode(decoded)


	# Header classes
	#

	class MSRPHeaderMeta(type):
	__classmap__ = {}

	name = None

	def __init__(cls, name, bases, dictionary):
	type.__init__(cls, name, bases, dictionary)
	if cls.name is not None:
	cls.__classmap__[cls.name] = cls

	def __call__(cls, args, *kw):
	if cls.name is not None:
	return super(MSRPHeaderMeta, cls).__call__(args, *kw) # specialized class, instantiated directly.
	else:
	return cls._instantiate_specialized_class(args, *kw) # non-specialized class, instantiated as a more specialized class if available.

	def _instantiate_specialized_class(cls, name, value):
	if name in cls.__classmap__:
	return super(MSRPHeaderMeta, cls.__classmap__[name]).__call__(value)
	else:
	return super(MSRPHeaderMeta, cls).__call__(name, value)


	class MSRPHeader(object):
	__metaclass__ = MSRPHeaderMeta

	name = None
	type = SimpleHeaderType

	def __init__(self, name, value):
	self.name = name
	if isinstance(value, str):
	self.encoded = value
	else:
	self.decoded = value

	def __eq__(self, other):
	if isinstance(other, MSRPHeader):
	return self.name == other.name and self.decoded == other.decoded
	return NotImplemented

	def __ne__(self, other):
	return not self == other

	@property
	def encoded(self):
	if self._encoded is None:
	self._encoded = self.type.encode(self._decoded)
	return self._encoded

	@encoded.setter
	def encoded(self, encoded):
	self._encoded = encoded
	self._decoded = None

	@property
	def decoded(self):
	if self._decoded is None:
	try:
	self._decoded = self.type.decode(self._encoded)
	except Exception as e:
	raise HeaderParsingError(self.name, str(e))
	return self._decoded

	@decoded.setter
	def decoded(self, decoded):
	if not isinstance(decoded, self.type.data_type):
	try:
	# noinspection PyArgumentList
	decoded = self.type.data_type(decoded)
	except Exception:
	raise TypeError('value must be an instance of {}'.format(self.type.data_type.__name__))
	self._decoded = decoded
	self._encoded = None


	class MSRPNamedHeader(MSRPHeader):
	def __init__(self, value):
	MSRPHeader.__init__(self, self.name, value)


	class ToPathHeader(MSRPNamedHeader):
	name = 'To-Path'
	type = URIHeaderType


	class FromPathHeader(MSRPNamedHeader):
	name = 'From-Path'
	type = URIHeaderType


	class MessageIDHeader(MSRPNamedHeader):
	name = 'Message-ID'
	type = SimpleHeaderType


	class SuccessReportHeader(MSRPNamedHeader):
	name = 'Success-Report'
	type = SuccessReportHeaderType


	class FailureReportHeader(MSRPNamedHeader):
	name = 'Failure-Report'
	type = FailureReportHeaderType


	class ByteRangeHeader(MSRPNamedHeader):
	name = 'Byte-Range'
	type = ByteRangeHeaderType

	@property
	def start(self):
	return self.decoded.start

	@property
	def end(self):
	return self.decoded.end

	@property
	def total(self):
	return self.decoded.total


	class StatusHeader(MSRPNamedHeader):
	name = 'Status'
	type = StatusHeaderType

	@property
	def code(self):
	return self.decoded.code

	@property
	def comment(self):
	return self.decoded.comment


	class ExpiresHeader(MSRPNamedHeader):
	name = 'Expires'
	type = IntegerHeaderType


	class MinExpiresHeader(MSRPNamedHeader):
	name = 'Min-Expires'
	type = IntegerHeaderType


	class MaxExpiresHeader(MSRPNamedHeader):
	name = 'Max-Expires'
	type = IntegerHeaderType


	class UsePathHeader(MSRPNamedHeader):
	name = 'Use-Path'
	type = URIHeaderType


	class WWWAuthenticateHeader(MSRPNamedHeader):
	name = 'WWW-Authenticate'
	type = DigestHeaderType


	class AuthorizationHeader(MSRPNamedHeader):
	name = 'Authorization'
	type = DigestHeaderType


	class AuthenticationInfoHeader(MSRPNamedHeader):
	name = 'Authentication-Info'
	type = ParameterListHeaderType


	class ContentTypeHeader(MSRPNamedHeader):
	name = 'Content-Type'
	type = SimpleHeaderType


	class ContentIDHeader(MSRPNamedHeader):
	name = 'Content-ID'
	type = SimpleHeaderType


	class ContentDescriptionHeader(MSRPNamedHeader):
	name = 'Content-Description'
	type = SimpleHeaderType


	class ContentDispositionHeader(MSRPNamedHeader):
	name = 'Content-Disposition'
	type = ContentDispositionHeaderType


	class UseNicknameHeader(MSRPNamedHeader):
	name = 'Use-Nickname'
	type = UTF8HeaderType


	class HeaderOrderMapping(dict):
	__levels__ = {
	0: ['To-Path'],
	1: ['From-Path'],
	2: ['Status', 'Message-ID', 'Byte-Range', 'Success-Report', 'Failure-Report'] +
	['Authorization', 'Authentication-Info', 'WWW-Authenticate', 'Expires', 'Min-Expires', 'Max-Expires', 'Use-Path', 'Use-Nickname'],
	3: ['Content-ID', 'Content-Description', 'Content-Disposition'],
	4: ['Content-Type']
	}

	def __init__(self):
	super(HeaderOrderMapping, self).__init__({name: level for level, name_list in self.__levels__.items() for name in name_list})

	def __missing__(self, key):
	return 3 if key.startswith('Content-') else 2

	sort_key = dict.__getitem__


	class HeaderOrdering(object):
	name_map = HeaderOrderMapping()
	sort_key = name_map.sort_key


	class MissingHeader(object):
	decoded = None


	class HeaderMapping(dict):
	def __init__(self, args, *kw):
	super(HeaderMapping, self).__init__(args, *kw)
	self.__modified__ = True

	def __repr__(self):
	return '{}({})'.format(self.__class__.__name__, super(HeaderMapping, self).__repr__())

	def __setitem__(self, key, value):
	super(HeaderMapping, self).__setitem__(key, value)
	self.__modified__ = True

	def __delitem__(self, key):
	super(HeaderMapping, self).__delitem__(key)
	self.__modified__ = True

	def __copy__(self):
	return self.__class__(self)

	def clear(self):
	super(HeaderMapping, self).clear()
	self.__modified__ = True

	def copy(self):
	return self.__class__(self)

	def pop(self, *args):
	result = super(HeaderMapping, self).pop(*args)
	self.__modified__ = True
	return result

	def popitem(self):
	result = super(HeaderMapping, self).popitem()
	self.__modified__ = True
	return result

	def setdefault(self, *args):
	result = super(HeaderMapping, self).setdefault(*args)
	self.__modified__ = True
	return result

	def update(self, args, *kw):
	super(HeaderMapping, self).update(args, *kw)
	self.__modified__ = True


	class MSRPData(object):
	__immutable__ = frozenset({'method', 'code', 'comment', 'headers'}) # Immutable attributes (cannot be overwritten)

	def __init__(self, transaction_id, method=None, code=None, comment=None, headers=None, data='', contflag='$'):
	if method is None and code is None:
	raise ValueError('either method or code must be specified')
	elif method is not None and code is not None:
	raise ValueError('method and code cannot be both specified')
	elif code is None and comment is not None:
	raise ValueError('comment should only be specified when code is specified')
	self.transaction_id = transaction_id
	self.method = method
	self.code = code
	self.comment = comment
	self.headers = HeaderMapping(headers or {})
	self.data = data
	self.contflag = contflag
	self.chunk_header = None # the chunk header (if the data was received from the network)
	self.chunk_footer = None # the chunk footer (if the data was received from the network)
	if method is not None:
	self.first_line = 'MSRP {} {}'.format(transaction_id, method)
	elif comment is None:
	self.first_line = 'MSRP {} {:03d}'.format(transaction_id, code)
	else:
	self.first_line = 'MSRP {} {:03d} {}'.format(transaction_id, code, comment)
	self.__modified__ = True

	def __setattr__(self, name, value):
	if name in self.__dict__:
	if name in self.__immutable__:
	raise AttributeError('Cannot overwrite attribute')
	elif name == 'transaction_id':
	self.first_line = self.first_line.replace(self.transaction_id, value)
	self.__modified__ = True
	super(MSRPData, self).__setattr__(name, value)

	def __delattr__(self, name):
	if name in self.__immutable__:
	raise AttributeError('Cannot delete attribute')
	super(MSRPData, self).__delattr__(name)

	def __str__(self): # TODO: make __str__ == encode()?
	return self.first_line

	def __repr__(self):
	description = self.first_line
	for name in sorted(self.headers, key=HeaderOrdering.sort_key):
	description += ' {}={!r}'.format(name, self.headers[name].encoded)
	description += ' len={}'.format(self.size)
	return '<{} at {:#x} {} {}>'.format(self.__class__.__name__, id(self), description, self.contflag)

	def __eq__(self, other):
	if isinstance(other, MSRPData):
	return self.first_line == other.first_line and self.headers == other.headers and self.data == other.data and self.contflag == other.contflag
	return NotImplemented

	def __ne__(self, other):
	return not self == other

	def copy(self):
	return self.__class__(self.transaction_id, self.method, self.code, self.comment, self.headers.copy(), self.data, self.contflag)

	def add_header(self, header):
	self.headers[header.name] = header

	def verify_headers(self):
	if 'To-Path' not in self.headers:
	raise HeaderParsingError('To-Path', 'header is missing')
	if 'From-Path' not in self.headers:
	raise HeaderParsingError('From-Path', 'header is missing')
	for header in self.headers.itervalues():
	_ = header.decoded

	@property
	def from_path(self):
	return self.headers.get('From-Path', MissingHeader).decoded

	@property
	def to_path(self):
	return self.headers.get('To-Path', MissingHeader).decoded

	@property
	def content_type(self):
	return self.headers.get('Content-Type', MissingHeader).decoded

	@property
	def message_id(self):
	return self.headers.get('Message-ID', MissingHeader).decoded

	@property
	def byte_range(self):
	return self.headers.get('Byte-Range', MissingHeader).decoded

	@property
	def status(self):
	return self.headers.get('Status', MissingHeader).decoded

	@property
	def failure_report(self):
	return self.headers.get('Failure-Report', MissingHeader).decoded or 'yes'

	@property
	def success_report(self):
	return self.headers.get('Success-Report', MissingHeader).decoded or 'no'

	@property
	def size(self):
	return len(self.data)

	@property
	def encoded_header(self):
	if self.__modified__ or self.headers.__modified__:
	lines = [self.first_line] + ['{}: {}'.format(name, self.headers[name].encoded) for name in sorted(self.headers, key=HeaderOrdering.sort_key)]
	if 'Content-Type' in self.headers:
	lines.append('\r\n')
	self.__dict__['encoded_header'] = '\r\n'.join(lines)
	self.__modified__ = self.headers.__modified__ = False
	return self.__dict__['encoded_header']

	@property
	def encoded_footer(self):
	return '\r\n-------{}{}\r\n'.format(self.transaction_id, self.contflag)

	def encode(self):
	return self.encoded_header + self.data + self.encoded_footer


	# noinspection PyProtectedMember
	class MSRPProtocol(LineReceiver):
	# TODO: _ in the method name is not legal, but sipsimple defined the FILE_OFFSET method
	first_line_re = re.compile(r'^MSRP ([A-Za-z0-9][A-Za-z0-9.+%=-]{3,31}) (?:([A-Z_]+)\|(\d{3})(?: (.+))?)$')

	MAX_LENGTH = 16384
	MAX_LINES = 64

	def __init__(self, msrp_transport):
	self.msrp_transport = msrp_transport
	self.term_buf = ''
	self.term_re = None
	self.term_substrings = []
	self.data = None
	self.line_count = 0

	def _reset(self):
	self.data = None
	self.line_count = 0

	def connectionMade(self):
	self.msrp_transport._got_transport(self.transport)

	def lineReceived(self, line):
	if self.data:
	if len(line) == 0:
	terminator = '\r\n-------' + self.data.transaction_id
	continue_flags = [c+'\r\n' for c in '$#+']
	self.term_buf = ''
	self.term_re = re.compile("^(.)%s([$#+])\r\n(.)$" % re.escape(terminator), re.DOTALL)
	self.term_substrings = [terminator[:i] for i in xrange(1, len(terminator)+1)] + [terminator+cont[:i] for cont in continue_flags for i in xrange(1, len(cont))]
	self.term_substrings.reverse()

	self.data.chunk_header += self.delimiter
	self.msrp_transport._data_start(self.data)
	self.setRawMode()
	else:
	match = self.term_re.match(line)
	if match:
	continuation = match.group(1)
	self.data.chunk_footer = line + self.delimiter
	self.msrp_transport._data_start(self.data)
	self.msrp_transport._data_end(continuation)
	self._reset()
	else:
	self.data.chunk_header += line + self.delimiter
	self.line_count += 1
	if self.line_count > self.MAX_LINES:
	self.msrp_transport.logger.received_illegal_data(self.data.chunk_header, self.msrp_transport)
	self._reset()
	return
	try:
	name, value = line.split(': ', 1)
	except ValueError:
	return # let this pass silently, we'll just not read this line. TODO: review this (ignore or drop connection?)
	else:
	self.data.add_header(MSRPHeader(name, value))
	else:
	# this is a new message. TODO: drop connection if first line cannot be parsed?
	match = self.first_line_re.match(line)
	if match:
	transaction_id, method, code, comment = match.groups()
	code = int(code) if code is not None else None
	self.data = MSRPData(transaction_id, method, code, comment)
	self.data.chunk_header = line + self.delimiter
	self.term_re = re.compile(r'^-------{}([$#+])$'.format(re.escape(transaction_id)))
	else:
	self.msrp_transport.logger.received_illegal_data(line + self.delimiter, self.msrp_transport)

	def lineLengthExceeded(self, line):
	self._reset()

	def rawDataReceived(self, data):
	data = self.term_buf + data
	match = self.term_re.match(data)
	if match: # we got the last data for this message
	contents, continuation, extra = match.groups()
	if contents:
	self.msrp_transport._data_write(contents, final=True)
	self.data.chunk_footer = '\r\n-------{}{}\r\n'.format(self.data.transaction_id, continuation)
	self.msrp_transport._data_end(continuation)
	self._reset()
	self.setLineMode(extra)
	else:
	for term in self.term_substrings:
	if data.endswith(term):
	self.term_buf = data[-len(term):]
	data = data[:-len(term)]
	break
	else:
	self.term_buf = ''
	self.msrp_transport._data_write(data, final=False)

	def connectionLost(self, reason=connectionDone):
	self.msrp_transport.connection_lost(reason)


	class ConnectInfo(object):
	host = None
	use_tls = True
	port = 2855

	def __init__(self, host=None, use_tls=None, port=None, credentials=None):
	if host is not None:
	self.host = host
	if use_tls is not None:
	self.use_tls = use_tls
	if port is not None:
	self.port = port
	self.credentials = credentials
	if self.use_tls and self.credentials is None:
	self.credentials = X509Credentials(None, None)

	@property
	def scheme(self):
	if self.use_tls:
	return 'msrps'
	else:
	return 'msrp'


	# use TLS_URI and TCP_URI ?
	class URI(ConnectInfo):
	_uri_re = re.compile(r'^(?P<scheme>.?)://(((?P<user>.?)@)?(?P<host>.?)(:(?P<port>[0-9]+?))?)(/(?P<session_id>.?))?;(?P<transport>.?)(;(?P<parameters>.))?$')

	def __init__(self, host=None, use_tls=None, user=None, port=None, session_id=None, transport="tcp", parameters=None, credentials=None):
	ConnectInfo.__init__(self, host or host_module.default_ip, use_tls=use_tls, port=port, credentials=credentials)
	if session_id is None:
	session_id = '%x' % random.getrandbits(80)
	if parameters is None:
	parameters = {}
	self.user = user
	self.transport = transport
	self.session_id = session_id
	self.parameters = parameters

	# noinspection PyTypeChecker
	@classmethod
	def parse(cls, value):
	match = cls._uri_re.match(value)
	if match is None:
	raise ParsingError('Cannot parse URI')

	uri_params = match.groupdict()
	scheme = uri_params.pop('scheme')

	if scheme not in ('msrp', 'msrps'):
	raise ParsingError('Invalid URI scheme: %r' % scheme)
	if uri_params['transport'] != 'tcp':
	raise ParsingError("Invalid URI transport: %r (only 'tcp' is accepted)" % uri_params['transport'])

	uri_params['use_tls'] = scheme == 'msrps'
	if uri_params['port'] is not None:
	uri_params['port'] = int(uri_params['port'])
	if uri_params['parameters'] is not None:
	try:
	uri_params['parameters'] = dict(param.split('=') for param in uri_params['parameters'].split(';'))
	except ValueError:
	raise ParsingError('Cannot parse URI parameters')

	return cls(**uri_params)

	def __repr__(self):
	arguments = 'host', 'use_tls', 'user', 'port', 'session_id', 'transport', 'parameters', 'credentials'
	return '{}({})'.format(self.__class__.__name__, ', '.join('{}={!r}'.format(name, getattr(self, name)) for name in arguments))

	def __str__(self):
	user_part = '{}@'.format(self.user) if self.user else ''
	port_part = ':{}'.format(self.port) if self.port else ''
	session_part = '/{}'.format(self.session_id) if self.session_id else ''
	parameter_parts = [';{}={}'.format(name, value) for name, value in self.parameters.iteritems()] if self.parameters else []
	return ''.join([self.scheme, '://', user_part, self.host, port_part, session_part, ';', self.transport] + parameter_parts)

	def __eq__(self, other):
	if self is other:
	return True
	if isinstance(other, URI):
	# MSRP URI comparison according to section 6.1 of RFC 4975
	self_items = self.use_tls, self.host.lower(), self.port, self.session_id, self.transport.lower()
	other_items = other.use_tls, other.host.lower(), other.port, other.session_id, other.transport.lower()
	return self_items == other_items
	return NotImplemented

	def __ne__(self, other):
	return not self == other

	def __hash__(self):
	return hash((self.use_tls, self.host.lower(), self.port, self.session_id, self.transport.lower()))

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