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protocol.py
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protocol.py
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import re
from collections import deque
from random import getrandbits
from twisted.protocols.basic import LineReceiver
class MSRPError(Exception):
pass
class ParsingError(MSRPError):
pass
class HeaderParsingError(ParsingError):
def __init__(self, header):
self.header = header
ParsingError.__init__(self, "Error parsing %s header" % header)
class MSRPHeaderMeta(type):
header_classes = {}
def __init__(cls, name, bases, dict):
type.__init__(cls, name, bases, dict)
try:
cls.header_classes[dict["name"]] = name
except KeyError:
pass
def _auth_header_quote(name, value, header_name):
if name == "qop":
if header_name == "WWW-Authenticate":
return '"%s"' % value
else:
return value
if name in ("stale", "algorithm", "nc"):
return value
else:
return '"%s"' % value
class MSRPHeader(object):
__metaclass__ = MSRPHeaderMeta
def __new__(cls, name, value):
if isinstance(value, str) and name in MSRPHeaderMeta.header_classes:
cls = eval(MSRPHeaderMeta.header_classes[name])
return object.__new__(cls)
def __init__(self, name, value):
self.name = name
if isinstance(value, str):
self.encoded = value
else:
self.decoded = value
def _raise_error(self):
raise HeaderParsingError(self.name)
def _get_encoded(self):
if self._encoded is None:
self._encoded = self._encode(self._decoded)
return self._encoded
def _set_encoded(self, encoded):
self._encoded = encoded
self._decoded = None
encoded = property(_get_encoded, _set_encoded)
def _get_decoded(self):
if self._decoded is None:
self._decoded = self._decode(self._encoded)
return self._decoded
def _set_decoded(self, decoded):
self._decoded = decoded
self._encoded = None
decoded = property(_get_decoded, _set_decoded)
def _decode(self, encoded):
return encoded
def _encode(self, decoded):
return decoded
def clone(self):
return self.__class__(self.name, self.encoded)
class MSRPNamedHeader(MSRPHeader):
def __new__(cls, *args):
if len(args) == 1:
value = args[0]
else:
value = args[1]
return MSRPHeader.__new__(cls, cls.name, value)
def __init__(self, *args):
if len(args) == 1:
value = args[0]
else:
value = args[1]
MSRPHeader.__init__(self, self.name, value)
class URIHeader(MSRPNamedHeader):
def _decode(self, encoded):
try:
return deque(parse_uri(uri) for uri in encoded.split(" "))
except ParsingError:
self._raise_error()
def _encode(self, decoded):
return " ".join([str(uri) for uri in decoded])
class IntegerHeader(MSRPNamedHeader):
def _decode(self, encoded):
try:
return int(encoded)
except ValueError:
self._raise_error()
def _encode(self, decoded):
return str(decoded)
class DigestHeader(MSRPNamedHeader):
def _decode(self, encoded):
try:
algo, params = encoded.split(" ", 1)
except ValueError:
self._raise_error()
if algo != "Digest":
self._raise_error()
try:
param_dict = dict((x.strip('"') for x in param.split("=", 1)) for param in params.split(", "))
except:
self._raise_error()
return param_dict
def _encode(self, decoded):
return "Digest " + ", ".join(['%s=%s' % (name, _auth_header_quote(name, value, self.name)) for name, value in decoded.iteritems()])
class ToPathHeader(URIHeader):
name = "To-Path"
class FromPathHeader(URIHeader):
name = "From-Path"
class MessageIDHeader(MSRPNamedHeader):
name = "Message-ID"
class SuccessReportHeader(MSRPNamedHeader):
name = "Success-Report"
def _decode(self, encoded):
if encoded not in ["yes", "no"]:
self._raise_error()
return encoded
class FailureReportHeader(MSRPNamedHeader):
name = "Failure-Report"
def _decode(self, encoded):
if encoded not in ["yes", "no", "partial"]:
self._raise_error()
return encoded
class ByteRangeHeader(MSRPNamedHeader):
name = "Byte-Range"
def _decode(self, encoded):
try:
rest, total = encoded.split("/")
fro, to = rest.split("-")
fro = int(fro)
except ValueError:
self._raise_error()
try:
to = int(to)
except ValueError:
if to != "*":
self._raise_error()
to = None
try:
total = int(total)
except ValueError:
if total != "*":
self._raise_error()
total = None
return [fro, to, total]
def _encode(self, decoded):
fro, to, total = decoded
if to is None:
to = "*"
if total is None:
total = "*"
return "%s-%s/%s" % (fro, to, total)
class StatusHeader(MSRPNamedHeader):
name = "Status"
def _decode(self, encoded):
try:
namespace, rest = encoded.split(" ", 1)
except ValueError:
self._raise_error()
if namespace != "000":
self._raise_error()
rest_sp = rest.split(" ", 1)
try:
if len(rest_sp[0]) != 3:
raise ValueError
code = int(rest_sp[0])
except ValueError:
self._raise_error()
try:
comment = rest_sp[1]
except IndexError:
comment = None
return code, comment
def _encode(self, decoded):
code, comment = decoded
encoded = "000 %03d" % code
if comment is not None:
encoded += " %s" % comment
return encoded
class ExpiresHeader(IntegerHeader):
name = "Expires"
class MinExpiresHeader(IntegerHeader):
name = "Min-Expires"
class MaxExpiresHeader(IntegerHeader):
name = "Max-Expires"
class UsePathHeader(URIHeader):
name = "Use-Path"
class WWWAuthenticateHeader(DigestHeader):
name = "WWW-Authenticate"
class AuthorizationHeader(DigestHeader):
name = "Authorization"
class AuthenticationInfoHeader(MSRPNamedHeader):
name = "Authentication-Info"
def _decode(self, encoded):
try:
param_dict = dict((x.strip('"') for x in param.split("=", 1)) for param in encoded.split(", "))
except:
self._raise_error()
return param_dict
def _encode(self, decoded):
return ", ".join(['%s=%s' % (name, _auth_header_quote(name, value, self.name)) for name, value in decoded.iteritems()])
class ContentTypeHeader(MSRPNamedHeader):
name = "Content-Type"
class ContentIDHeader(MSRPNamedHeader):
name = "Content-ID"
class ContentDescriptionHeader(MSRPNamedHeader):
name = "Content-Description"
class ContentDispositionHeader(MSRPNamedHeader):
name = "Content-Disposition"
def _decode(self, encoded):
try:
sp = encoded.split(";")
disposition = sp[0]
parameters = dict(param.split("=", 1) for param in sp[1:])
except:
self._raise_error()
return [disposition, parameters]
def _encode(self, decoded):
disposition, parameters = decoded
return ";".join([disposition] + ["%s=%s" % pair for pair in parameters.iteritems()])
class MSRPData(object):
def __init__(self, transaction_id, method=None, code=None, comment=None, data=''):
self.transaction_id = transaction_id
self.method = method
self.code = code
self.comment = comment
self.data = data
self.headers = {}
def __str__(self):
if self.method is None:
description = "MSRP response: %03d" % self.code
if self.comment is not None:
description += " %s" % self.comment
else:
description = "MSRP %s request" % self.method
return description
def add_header(self, header):
self.headers[header.name] = header
def verify_headers(self):
try: # Decode To-/From-path headers first to be able to send responses
self.headers["To-Path"].decoded
self.headers["From-Path"].decoded
except KeyError, e:
raise HeaderParsingError(e.args[0])
for header in self.headers.itervalues():
header.decoded
@property
def failure_report(self):
if "Failure-Report" in self.headers:
return self.headers["Failure-Report"].decoded
else:
return "yes"
@property
def success_report(self):
if "Success-Report" in self.headers:
return self.headers["Success-Report"].decoded
else:
return "no"
def encode_start(self):
data = []
if self.method is not None:
data.append("MSRP %(transaction_id)s %(method)s" % self.__dict__)
else:
data.append("MSRP %(transaction_id)s %(code)03d" % self.__dict__ + (self.comment is not None and " %s" % self.comment or ""))
headers = self.headers.copy()
data.append("To-Path: %s" % headers.pop("To-Path").encoded)
data.append("From-Path: %s" % headers.pop("From-Path").encoded)
for hnameval in [(hname, headers.pop(hname).encoded) for hname in headers.keys() if not hname.startswith("Content-")]:
data.append("%s: %s" % hnameval)
for hnameval in [(hname, headers.pop(hname).encoded) for hname in headers.keys() if hname != "Content-Type"]:
data.append("%s: %s" % hnameval)
if len(headers) > 0:
data.append("Content-Type: %s" % headers["Content-Type"].encoded)
data.append("")
data.append("")
return "\r\n".join(data)
def encode_end(self, continuation):
return "\r\n-------%s%s\r\n" % (self.transaction_id, continuation)
def encode(self, continuation='$'):
return self.encode_start() + self.data + self.encode_end(continuation)
def clone(self):
other = self.__class__(self.transaction_id, self.method, self.code, self.comment, self.data)
for header in self.headers.itervalues():
other.add_header(header.clone())
return other
class MSRPProtocol(LineReceiver):
MAX_LENGTH = 16384
MAX_LINES = 64
def __init__(self):
self.peer = None
self._reset()
def _reset(self):
self.data = None
self.line_count = 0
def connectionMade(self):
self.peer = self.factory.get_peer(self)
def lineReceived(self, line):
if self.data:
if len(line) == 0:
self.term_buf_len = 12 + len(self.data.transaction_id)
self.term_buf = ""
self.term = re.compile("^(.*)\r\n-------%s([$#+])\r\n(.*)$" % re.escape(self.data.transaction_id), re.DOTALL)
self.peer.data_start(self.data)
self.setRawMode()
else:
match = self.term.match(line)
if match:
continuation = match.group(1)
self.peer.data_start(self.data)
self.peer.data_end(continuation)
self._reset()
else:
self.line_count += 1
if self.line_count > self.MAX_LINES:
self._reset()
return
try:
hname, hval = line.split(": ", 2)
except ValueError:
return # let this pass silently, we'll just not read this line
else:
self.data.add_header(MSRPHeader(hname, hval))
else: # we received a new message
try:
msrp, transaction_id, rest = line.split(" ", 2)
except ValueError:
return # drop connection?
if msrp != "MSRP":
return # drop connection?
method, code, comment = None, None, None
rest_sp = rest.split(" ", 1)
try:
if len(rest_sp[0]) != 3:
raise ValueError
code = int(rest_sp[0])
except ValueError: # we have a request
method = rest_sp[0]
else: # we have a response
if len(rest_sp) > 1:
comment = rest_sp[1]
self.data = MSRPData(transaction_id, method, code, comment)
self.term = re.compile("^-------%s([$#+])$" % re.escape(transaction_id))
def lineLengthExceeded(self, line):
self._reset()
def rawDataReceived(self, data):
match_data = self.term_buf + data
match = self.term.match(match_data)
if match: # we got the last data for this message
contents, continuation, extra = match.groups()
contents = contents[len(self.term_buf):]
if contents:
self.peer.write_chunk(contents)
self.peer.data_end(continuation)
self._reset()
self.setLineMode(extra)
else:
self.peer.write_chunk(data)
self.term_buf = match_data[-self.term_buf_len:]
def connectionLost(self, reason):
if self.peer:
self.peer.connection_lost(reason.value)
_re_uri = re.compile("^(?P<scheme>.*?)://(((?P<user>.*?)@)?(?P<host>.*?)(:(?P<port>[0-9]+?))?)(/(?P<session_id>.*?))?;(?P<transport>.*?)(;(?P<parameters>.*))?$")
def parse_uri(uri_str):
match = _re_uri.match(uri_str)
if match is None:
raise ParsingError("Cannot parse URI")
uri_params = match.groupdict()
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")
scheme = uri_params.pop("scheme")
if scheme == "msrp":
uri_params["use_tls"] = False
elif scheme == "msrps":
uri_params["use_tls"] = True
else:
raise ParsingError("Invalid scheme user in URI: %s" % scheme)
if uri_params["transport"] != "tcp":
raise ParsingError('Invalid transport in URI, only "tcp" is accepted: %s' % uri_params["transport"])
return URI(**uri_params)
class URI(object):
def __init__(self, host, use_tls = False, user = None, port = None, session_id = None, transport = "tcp", parameters = None):
self.use_tls = use_tls
self.user = user
self.host = host
self.port = port
self.session_id = session_id
self.transport = transport
if parameters is None:
self.parameters = {}
else:
self.parameters = parameters
def __str__(self):
uri_str = []
if self.use_tls:
uri_str.append("msrps://")
else:
uri_str.append("msrp://")
if self.user:
uri_str.extend([self.user, "@"])
uri_str.append(self.host)
if self.port:
uri_str.extend([":", str(self.port)])
if self.session_id:
uri_str.extend(["/", self.session_id])
uri_str.extend([";", self.transport])
for key, value in self.parameters.iteritems():
uri_str.extend([";", key, "=", value])
return "".join(uri_str)
def __eq__(self, other):
"""MSRP URI comparison according to section 6.1 of RFC 4975"""
if self is other:
return True
if self.use_tls != other.use_tls:
return False
if self.host.lower() != other.host.lower():
return False
if self.port != other.port:
return False
if self.session_id != other.session_id:
return False
if self.transport.lower() != other.transport.lower():
return False
return True
def __ne__(self, other):
return not self == other
def generate_transaction_id():
return '%024x' % getrandbits(96)

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