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transport.py
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# Copyright (C) 2008 AG Projects. See LICENSE for details
import random
from copy import copy
from application import log
from eventlet.twistedutil.protocol import GreenTransportBase
from msrplib import protocol, MSRPError
class ChunkParseError(MSRPError):
"""Failed to parse incoming chunk"""
class MSRPTransactionError(MSRPError):
def __init__(self, comment=None, code=None):
if comment is not None:
self.comment = comment
if code is not None:
self.code = code
if not hasattr(self, 'code'):
raise TypeError("must provide 'code'")
def __str__(self):
if hasattr(self, 'comment'):
return '%s %s' % (self.code, self.comment)
else:
return str(self.code)
# XXX from these exception names it's unclear whether it's raised
# because of an error response from a remote party or it's a locally
# generated error (-- it's latter)
class MSRPBadRequest(MSRPTransactionError):
code = 400
comment = 'Bad Request'
def __str__(self):
return 'Remote party sent bogus data'
class MSRPNoSuchSessionError(MSRPTransactionError):
code = 481
comment = 'No such session'
data_start, data_end, data_write, data_final_write = xrange(4)
class MSRPProtocol_withLogging(protocol.MSRPProtocol):
traffic_logger = None
state_logger = None
_new_chunk = False
def rawDataReceived(self, data):
if self.traffic_logger:
self.traffic_logger.report_in(data, self.transport)
protocol.MSRPProtocol.rawDataReceived(self, data)
def lineReceived(self, line):
if self.traffic_logger:
self.traffic_logger.report_in(line+self.delimiter, self.transport, self._new_chunk)
self._new_chunk = False
protocol.MSRPProtocol.lineReceived(self, line)
def connectionLost(self, reason):
if self.state_logger:
self.state_logger.report_disconnected(self.transport, reason)
protocol.MSRPProtocol.connectionLost(self, reason)
def setLineMode(self, extra):
self._new_chunk = True
return protocol.MSRPProtocol.setLineMode(self, extra)
def make_response(chunk, code, comment):
"""Construct a response to a request as described in RFC4975 Section 7.2.
If the response is not needed, return None.
If a required header missing, raise ChunkParseError.
"""
if chunk.failure_report=='no':
return
if chunk.failure_report=='partial' and code==200:
return
if not chunk.headers.get('To-Path'):
raise ChunkParseError('missing To-Path header: %r' % chunk)
if not chunk.headers.get('From-Path'):
raise ChunkParseError('missing From-Path header: %r' % chunk)
to_path = [chunk.headers['From-Path'].decoded[0]]
if chunk.method=='SEND':
from_path = [chunk.headers['To-Path'].decoded[-1]]
else:
from_path = chunk.headers['To-Path'].decoded
response = protocol.MSRPData(chunk.transaction_id, code=code, comment=comment)
response.add_header(protocol.ToPathHeader(to_path))
response.add_header(protocol.FromPathHeader(from_path))
return response
class MSRPTransport(GreenTransportBase):
protocol_class = MSRPProtocol_withLogging
def __init__(self, local_uri, traffic_logger=None, state_logger=None):
GreenTransportBase.__init__(self)
if not isinstance(local_uri, protocol.URI):
raise TypeError('Not MSRP URI instance: %r' % (local_uri, ))
# The following members define To-Path and From-Path headers as following:
# * Outgoing request:
# From-Path: local_uri
# To-Path: local_path + remote_path + [remote_uri]
# * Incoming request:
# From-Path: remote_path + remote_uri
# To-Path: remote_path + local_path + [local_uri] # XXX
self.local_uri = local_uri
self.local_path = []
self.remote_uri = None
self.remote_path = []
self.traffic_logger = traffic_logger
self.state_logger = state_logger
self._msrpdata = None
def next_host(self):
if self.local_path:
return self.local_path[0]
return self.full_remote_path[0]
def set_local_path(self, lst):
self.local_path = lst
@property
def full_local_path(self):
"suitable to put into INVITE"
return self.local_path + [self.local_uri]
@property
def full_remote_path(self):
return self.remote_path + [self.remote_uri]
def make_chunk(self, transaction_id=None, method='SEND', code=None, comment=None, data='',
contflag=None, start=1, end=None, length=None):
"""Make a new MSRPData object with From and To headers set up"""
if transaction_id is None:
transaction_id = '%x' % random.getrandbits(64)
chunk = protocol.MSRPData(transaction_id=transaction_id, method=method, code=code, comment=comment)
chunk.add_header(protocol.ToPathHeader(self.local_path + self.remote_path + [self.remote_uri]))
chunk.add_header(protocol.FromPathHeader([self.local_uri]))
if end is None:
end = start - 1 + len(data)
if length is None:
length = start - 1 + len(data)
if contflag is None:
if end == length:
contflag = '$'
else:
contflag = '+'
chunk.add_header(protocol.ByteRangeHeader((start, end, length)))
chunk.add_header(protocol.MessageIDHeader('%x' % random.getrandbits(64)))
# Byte-Range and Message-ID are neccessary because otherwise msrprelay does not work
chunk.data = data
chunk.contflag = contflag
return chunk
def build_protocol(self):
p = GreenTransportBase.build_protocol(self)
p.traffic_logger = self.traffic_logger
p.state_logger = self.state_logger
return p
def _data_start(self, data):
self._queue.send((data_start, data))
def _data_end(self, continuation):
self._queue.send((data_end, continuation))
def _data_write(self, contents, final):
if final:
self._queue.send((data_write, contents))
else:
self._queue.send((data_final_write, contents))
def write(self, data):
if self.traffic_logger:
self.traffic_logger.report_out(data, self.transport)
return GreenTransportBase.write(self, data)
def read_chunk(self, size=None):
"""Wait for a new chunk and return it.
If there was an error, lose Connection and raise ChunkParseError
In case of unintelligible input, lose the connection and return None.
When connection is closed, raise the reason of the closure (e.g. ConnectionDone).
If the data already read exceeds `size', stop reading the data and return
a "virtual" chunk, i.e. the one that does not actually correspond the the real
MSRP chunk. Such chunks have Byte-Range header fixed and continuation that is '+';
they also posses 'segment' attribute, an integer, starting with 1 and increasing
with every new segment of the chunk.
Note, that `size' only hints when to interrupt the segment but does not affect
how the data is read from socket. You may have segments bigger than `size' and it's
legal to set `size' to zero (which would mean return a chunk as long as you get
some data, regardless how small)
"""
data = ''
if self._msrpdata is None:
func, msrpdata = self._wait()
if func!=data_start:
self.state_logger.write('Bad data: %r %r' % (func, msrpdata))
self.loseConnection()
raise ChunkParseError
else:
msrpdata = self._msrpdata
func, param = self._wait()
while func==data_write:
data += param
if size is not None and len(data)>=size:
if msrpdata.segment is None:
msrpdata.segment = 1
else:
msrpdata.segment += 1
self._msrpdata = copy(msrpdata)
msrpdata.data = data
msrpdata.contflag = '+'
msrpdata.final = False
return msrpdata
func, param = self._wait()
if func == data_final_write:
data += param
func, param = self._wait()
if func != data_end:
self.state_logger.write('Bad data: %r %r' % (func, param))
self.loseConnection()
raise ChunkParseError
if param not in "$+#":
self.state_logger.write('Bad data: %r %r' % (func, param))
self.loseConnection()
raise ChunkParseError
msrpdata.data = data
msrpdata.contflag = param
self._msrpdata = None
self.state_logger.dbg('read_chunk -> %r' % (msrpdata, ))
return msrpdata
def _set_full_remote_path(self, full_remote_path):
"as received in response to INVITE"
if not all(isinstance(x, protocol.URI) for x in full_remote_path):
raise TypeError('Not all elements are MSRP URI: %r' % full_remote_path)
self.remote_uri = full_remote_path[-1]
self.remote_path = full_remote_path[:-1]
def bind(self, full_remote_path):
self._set_full_remote_path(full_remote_path)
chunk = self.make_chunk()
self.write(chunk.encode())
response = self.read_chunk()
if response.code != 200:
self.loseConnection(sync=False)
raise MSRPNoSuchSessionError('Cannot bind session: %s' % response)
def write_response(self, chunk, code, comment):
"""Generate and write the response, lose the connection in case of error"""
try:
response = make_response(chunk, code, comment)
except ChunkParseError, ex:
log.error('Failed to generate a response: %s' % ex)
self.loseConnection(blocking=False)
raise
except Exception:
log.error('Failed to generate a response')
log.err()
self.loseConnection(blocking=False)
raise
else:
if response is not None:
self.write(response.encode())
def accept_binding(self, full_remote_path):
self._set_full_remote_path(full_remote_path)
chunk = self.read_chunk()
error = self.check_incoming_SEND_chunk(chunk)
if error is None:
code, comment = 200, 'OK'
else:
code, comment = error.code, error.comment
self.write_response(chunk, code, comment)
if 'Content-Type' in chunk.headers or len(chunk.data)>0:
# deliver chunk to read_chunk
raise NotImplementedError
def check_incoming_SEND_chunk(self, chunk):
assert chunk.method=='SEND', repr(chunk)
try:
ToPath = chunk.headers['To-Path']
except KeyError:
return MSRPBadRequest('To-Path header missing')
try:
FromPath = chunk.headers['From-Path']
except KeyError:
return MSRPBadRequest('From-Path header missing')
ToPath = list(ToPath.decoded)
FromPath = list(FromPath.decoded)
ExpectedTo = [self.local_uri]
ExpectedFrom = self.local_path + self.remote_path + [self.remote_uri]
if ToPath!=ExpectedTo or FromPath!=ExpectedFrom:
log.error('To-Path: expected %r, got %r' % (ExpectedTo, ToPath))
return MSRPNoSuchSessionError('Invalid To-Path')
if FromPath != ExpectedFrom:
log.error('From-Path: expected %r, got %r' % (ExpectedFrom, FromPath))
return MSRPNoSuchSessionError('Invalid From-Path')

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