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transport.py
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# Copyright (C) 2008-2009 AG Projects. See LICENSE for details
import random
from application import log
from twisted.internet.error import ConnectionDone
from eventlet.twistedutil.protocol import GreenTransportBase
from msrplib import protocol, MSRPError
from msrplib.trafficlog import Logger
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)
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):
_new_chunk = False
def rawDataReceived(self, data):
self._recepient.logger.report_in(data, self.transport)
protocol.MSRPProtocol.rawDataReceived(self, data)
def lineReceived(self, line):
self._recepient.logger.report_in(line+self.delimiter, self.transport, self._new_chunk)
self._new_chunk = False
protocol.MSRPProtocol.lineReceived(self, line)
def connectionLost(self, reason):
msg = 'Closed connection to %s:%s' % (self.transport.getPeer().host, self.transport.getPeer().port)
if not isinstance(reason.value, ConnectionDone):
msg += ' (%s)' % reason.getErrorMessage()
self._recepient.logger.info(msg)
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, logger):
GreenTransportBase.__init__(self)
if local_uri is not None and 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
if logger is None:
logger = Logger()
self.logger = logger
self.local_path = []
self.remote_uri = None
self.remote_path = []
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, message_id=None):
"""Make a new MSRPData object with proper From-Path and To-Path headers set up.
In addition add Byte-Range and Message-ID headers.
"""
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 = '$'
else:
contflag = '+'
chunk.add_header(protocol.ByteRangeHeader((start, end, length)))
if message_id is None:
chunk.add_header(protocol.MessageIDHeader('%x' % random.getrandbits(64)))
else:
chunk.add_header(protocol.MessageIDHeader(message_id))
# Byte-Range and Message-ID are neccessary because otherwise msrprelay does not work
if method=='SEND':
chunk.data = data
chunk.contflag = contflag
else:
chunk.data = ''
chunk.contflag = '$'
return chunk
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_final_write, contents))
else:
self._queue.send((data_write, contents))
def write(self, bytes, wait=True):
"""Write `bytes' to the socket. If `wait' is true, wait for an operation to complete"""
self.logger.report_out(bytes, self.transport)
return GreenTransportBase.write(self, bytes, wait)
def read_chunk(self, size=None):
"""Wait for a new chunk and return it.
If there was an error, close the connection and raise ChunkParseError.
In case of unintelligible input, lose the connection and return None.
When the 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 changed to match the number of
bytes read and continuation that is '+'; they also possess '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.logger.debug('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 = msrpdata.copy()
msrpdata.data = data
msrpdata.contflag = '+'
msrpdata.final = False
fro, to, total = msrpdata.byte_range
msrpdata.add_header(protocol.ByteRangeHeader((fro, fro+len(msrpdata.data), total)))
self._msrpdata.add_header(protocol.ByteRangeHeader((fro+len(msrpdata.data), None, total)))
self.logger.debug('read_chunk -> (virtual) %r' % (msrpdata, ))
return msrpdata
func, param = self._wait()
if func == data_final_write:
data += param
func, param = self._wait()
if func != data_end:
self.logger.debug('Bad data: %r %s' % (func, repr(param)[:100]))
self.loseConnection()
raise ChunkParseError
if param not in "$+#":
self.logger.debug('Bad data: %r %s' % (func, repr(param)[:100]))
self.loseConnection()
raise ChunkParseError
msrpdata.data = data
msrpdata.contflag = param
self._msrpdata = None
self.logger.debug('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(wait=False)
raise MSRPNoSuchSessionError('Cannot bind session: %s' % response)
def write_response(self, chunk, code, comment, wait=True):
"""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(wait=False)
raise
except Exception:
log.error('Failed to generate a response')
log.err()
self.loseConnection(wait=False)
raise
else:
if response is not None:
self.write(response.encode(), wait=wait)
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):
"""Check the 'To-Path' and 'From-Path' of the incoming SEND chunk.
Return None is the paths are valid for this connection.
If an error is detected and MSRPError is created and returned.
"""
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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