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transport.py
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# Copyright (C) 2008 AG Projects. See LICENSE for details
from __future__ import with_statement
import sys
from eventlet.coros import Job, queue
from eventlet.twistedutil.protocol import GreenTransportBase
from eventlet.hubs.twistedr import callLater
from msrplib import protocol, MSRPError
from msrplib.util import random_string
# need Message-ID and Byte-Range headers in every chunk, because msrprelay fails otherwise
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):
try:
comment = self.comment
except AttributeError:
return str(self.code)
else:
return '%s %s' % (self.code, self.comment)
# 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 MSRPBadContentType(MSRPTransactionError):
code = 415
comment = 'Unsupported media type'
class MSRPSessionError(MSRPTransactionError):
code = 481
comment = 'No such session'
data_start, data_end, write_chunk = range(3)
class Peer:
def __init__(self, channel):
self.channel = channel
def data_start(self, data):
self.channel.send((data_start, data))
def data_end(self, continuation):
self.channel.send((data_end, continuation))
def write_chunk(self, contents):
self.channel.send((write_chunk, contents))
def connection_lost(self, reason):
self.channel.send_exception(reason.type, reason.value, reason.tb)
class MSRPProtocol_withLogging(protocol.MSRPProtocol):
traffic_logger = None
_new_chunk = True
def __init__(self, gtransport, queue):
self.gtransport = gtransport
self._queue = queue
protocol.MSRPProtocol.__init__(self)
def connectionMade(self):
self.gtransport.init_transport(self.transport)
del self.gtransport
self.peer = Peer(self._queue)
del self._queue
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.peer:
self.peer.connection_lost(reason)
def setLineMode(self, extra):
self._new_chunk = True
return protocol.MSRPProtocol.setLineMode(self, extra)
def make_SEND_response(chunk, code, comment):
"""Construct a response to SEND request as described in RFC4975 Section 7.2"""
to_path = [chunk.headers['From-Path'].decoded[0]]
from_path = [chunk.headers['To-Path'].decoded[-1]]
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 Message(str):
pass
class LocalResponse(object):
def __init__(self, code, comment):
self.code = code
self.comment = comment
def __repr__(self):
return '<LocalResponse %s %s>' % (self.code, self.comment)
Response200OK = LocalResponse(200, "OK")
Response408Timeout = LocalResponse(408, "Local transaction timed out")
# XXX LocalResponse has the same attributes as MSRPTransactionError
class MSRPSession(GreenTransportBase):
"""An MSRP session that exclusively uses the connection.
QQQ: there's 1-to-1 mapping between session and connection because
msrprelay does not support otherwise.
* Maintain list events for each unconfirmed chunks and fire them when the
response arrives
Does not do:
* multiple messages
"""
protocol_class = MSRPProtocol_withLogging
RESPONSE_TIMEOUT = 30
debug = True
def __init__(self, local_uri, traffic_logger=None, allowed_content_types=None, debug=None):
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.allowed_content_types = allowed_content_types
if debug is not None:
self.debug = debug
self.expected_responses = {}
self.reader_job = None
self.incoming = queue(1)
#self.chunks = {} # maps message_id to StringIO instance that represents contents of the message
def next_host(self):
if self.local_path:
return self.local_path[0]
return self.full_remote_path[0]
def use_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='$'):
"""Make a new MSRPData object with From and To headers set up"""
if transaction_id is None:
transaction_id=random_string(12)
chunk = protocol.MSRPData(transaction_id=transaction_id, method=method, code=code, comment=comment)
chunk.add_header(protocol.ToPathHeader(self.local_path + self.remote_path + [self.remote_uri]))
chunk.add_header(protocol.FromPathHeader([self.local_uri]))
# Byte-Range and Message-ID are neccessary because otherwise msrprelay does not work
chunk.add_header(protocol.ByteRangeHeader((1, len(data), len(data))))
chunk.add_header(protocol.MessageIDHeader(str(random_string(10))))
chunk.data = data
chunk.contflag = contflag
return chunk
def build_protocol(self):
p = GreenTransportBase.build_protocol(self)
p.traffic_logger = self.traffic_logger
return p
def write(self, data):
if self.traffic_logger:
self.traffic_logger.report_out(data, self.transport)
return self.transport.write(data)
def write_chunk(self, chunk):
"""Encode chunk and write it to the underlying transport"""
self.write(chunk.encode())
def write_SEND_response(self, chunk, code, comment):
assert chunk.method=='SEND', repr(chunk)
if chunk.failure_report=='no':
return
if chunk.failure_report=='partial' and code==200:
return
try:
response = make_SEND_response(chunk, code, comment)
except Exception:
# there could an exception if chunk is somehow broken
if self.debug:
raise
else:
return self.write_chunk(response)
def _wait_chunk(self):
"""Wait for a new chunk. Return it bypassing self.incoming"""
data = ''
func, msrpdata = self._wait()
if func!=data_start:
raise MSRPBadRequest
func, param = self._wait()
while func==write_chunk:
data += param
func, param = self._wait()
if func!=data_end:
raise MSRPBadRequest
if param not in "$+#":
raise MSRPBadRequest
msrpdata.data = data
msrpdata.contflag = param
return msrpdata
def _wait_chunk_respond_errors(self, raise_on_error=False):
"""Wait for a new chunk. Return it bypassing self.incoming.
Send the following responses in appropriate situations:
* 400 Bad Request
* 481 No Such Session Here
Then continue receiving if raise_on_error is False, otherwise an exception is raised.
"""
while True:
try:
chunk = self._wait_chunk()
except MSRPBadRequest, error:
if chunk.method == 'SEND':
# QQQ may send this more than once in a row for the same transaction
# QQQ chunk is incomplete here, may have no to-path/from-path headers
self.write_SEND_response(chunk, error.code, error.comment)
if raise_on_error:
raise
else:
# QQQ do I need to check that To-Path and From-Path
# present or is it handled by msrp_protocol
if chunk.method=='SEND':
error = self.check_path_headers_SEND(chunk)
if error is not None:
self.write_SEND_response(chunk, error.code, error.comment)
if raise_on_error:
raise error
else:
continue
return chunk
def _reader(self, raise_on_error=False):
"""Wait forever for new chunks.
Send the good ones to self.incoming queue.
Pop and notify an event in self.expected_responses
when transaction response is received.
"""
try:
while True:
chunk = self._wait_chunk_respond_errors(raise_on_error=raise_on_error)
if chunk.method is None: # response
try:
event, timer = self.expected_responses.pop(chunk.transaction_id)
except KeyError:
continue
else:
if timer is not None:
timer.cancel()
event.send(chunk)
elif chunk.method=='SEND':
error = self.check_content_type(chunk)
if error is not None:
self.write_SEND_response(chunk, error.code, error.comment)
if raise_on_error:
raise
else:
self.write_SEND_response(chunk, 200, "OK")
self.incoming.send(chunk)
elif chunk.method=='REPORT':
pass
else:
pass # respond 506
except:
self.incoming.send_exception(*sys.exc_info())
raise
def receive_chunk(self):
if self.reader_job:
return self.incoming.wait()
else:
self.reader_job.poll() # re-raise the exception that killed reader
def send_chunk(self, chunk, event=None):
"""Send `chunk'. Report the result via `event'.
When `event' argument is present, it will be used to report
the response to the caller. When a real response is received,
`event' is fired with MSRPData object. When the response is
generated locally it's a LocalResponse instance.
If no response was received after RESPONSE_TIMEOUT seconds,
* 408 response is generated if Failure-Report was 'yes' or absent
* 200 response is generated if Failure-Report was 'partial' or 'no'
Note that it's rather wasteful to provide `event' argument other than None
for chunks with Failure-Report='no' since it will always fire 30 seconds later
with 200 result (unless the other party is broken and ignores Failure-Report header)
"""
self.reader_job.poll() # re-raise the exception that killed reader
id = chunk.transaction_id
assert id not in self.expected_responses, "MSRP transaction %r is already in progress" % id
if event is not None:
# since reader is in another greenlet and write_chunk may block,
# let's setup ResponseEventTimer before write_chunk() call, just in case
event_timer = [event, None]
self.expected_responses[id] = event_timer
try:
self.write_chunk(chunk)
# must start timer after data was submitted to the OS. However, twisted's transport
# introduces additional buffer. I cannot just disable it (by setting bufferSize to 1)
# because bufferSize applies both to write buffering and recv's argument (why?)
# need to hack twisted.internet.tcp.
except:
if event is not None and id in self.expected_responses:
del self.expected_responses[id]
raise
else:
if event is not None:
timeout_error = Response408Timeout if chunk.failure_report=='yes' else Response200OK
from twisted.internet import reactor
timer = callLater(reactor, self.RESPONSE_TIMEOUT, self._response_timeout, id, timeout_error)
event_timer[1] = timer
def _response_timeout(self, id, timeout_error):
try:
event, timer = self.expected_responses.pop(id)
except KeyError:
pass
else:
if timer is not None:
timer.cancel()
event.send(timeout_error)
def check_path_headers_SEND(self, chunk):
assert chunk.method=='SEND', repr(chunk)
ToPath = list(chunk.headers['To-Path'].decoded)
FromPath = list(chunk.headers['From-Path'].decoded)
ExpectedTo = [self.local_uri]
ExpectedFrom = self.local_path + self.remote_path + [self.remote_uri]
if ToPath!=ExpectedTo or FromPath!=ExpectedFrom:
return MSRPSessionError('To-Path: expected %r, got %r' % (ExpectedTo, ToPath))
if FromPath != ExpectedFrom:
return MSRPSessionError('From-Path: expected %r, got %r' % (ExpectedFrom, FromPath))
def check_content_type(self, chunk):
if chunk.headers.get('Content-Type') is None:
return MSRPBadContentType('Content-type header missing')
if self.allowed_content_types is not None:
if chunk.headers['Content-Type'].decoded not in self.allowed_content_types:
return MSRPBadContentType
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(chunk)
response = self._wait_chunk()
if response.code != 200:
raise MSRPSessionError('Cannot bind session: %s' % response)
self.reader_job = Job.spawn_new(self._reader, self.debug)
def accept_binding(self, full_remote_path):
self._set_full_remote_path(full_remote_path)
chunk = self._wait_chunk_respond_errors(raise_on_error=True)
self.write_SEND_response(chunk, 200, "OK")
if 'Content-Type' in chunk.headers or len(chunk.data)>0:
self.incoming.send(chunk)
self.reader_job = Job.spawn_new(self._reader, self.debug)
def make_message(self, msg, content_type):
chunk = self.make_chunk(data=msg)
chunk.add_header(protocol.ContentTypeHeader(content_type))
return chunk
def send_message(self, msg, content_type):
chunk = self.make_message(msg, content_type)
self.send_chunk(chunk)
return chunk

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