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session.py
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# Copyright (C) 2008-2009 AG Projects. See LICENSE for details
from __future__ import with_statement
import sys
from time import time
from twisted.internet.error import ConnectionClosed, ConnectionDone
from gnutls.errors import GNUTLSError
from eventlet import api, coros, proc
from eventlet.twistedutil.protocol import ValueQueue
from msrplib import protocol, MSRPError
from msrplib.transport import make_response, MSRPTransactionError
ConnectionClosedErrors = (ConnectionClosed, GNUTLSError)
class MSRPSessionError(MSRPError):
pass
class MSRPBadContentType(MSRPTransactionError):
code = 415
comment = 'Unsupported media type'
class LocalResponse(MSRPTransactionError):
def __repr__(self):
return '<LocalResponse %s %s>' % (self.code, self.comment)
Response200OK = LocalResponse("OK", 200)
Response408Timeout = LocalResponse("Timed out while waiting for transaction response", 408)
class MSRPSession(object):
# if incoming chunk is bigger than this, split it (for the reporting purposes)
INCOMING_CHUNK_SIZE = 1024*16
RESPONSE_TIMEOUT = 30
SHUTDOWN_TIMEOUT = 1
def __init__(self, msrptransport, allowed_content_types=None):
self.msrp = msrptransport
self.state_logger = self.msrp.state_logger
self.allowed_content_types = allowed_content_types
self.expected_responses = {}
#self.expected_success_reports = {}
self.outgoing = coros.queue()
self.reader_job = proc.spawn(self._reader)
self.writer_job = proc.spawn(self._writer)
self.state = 'CONNECTED' # -> 'FLUSHING' -> 'CLOSING' -> 'DONE'
# in FLUSHING writer sends only while there's something in the outgoing queue
# then it exits and sets state to 'CLOSING' which makes reader only pay attention
# to responses and success reports. (XXX it could now discard incoming data chunks
# with direct write() since writer is dead)
self.reader_job.link(self.writer_job)
self.incoming = ValueQueue()
self.last_expected_response = 0
def set_state(self, state):
self.state_logger.dbg('%s (was %s)' % (state, self.state))
self.state = state
@property
def connected(self):
return self.state=='CONNECTED'
def shutdown(self, sync=True):
self.set_state('FLUSHING')
self.outgoing.send(None)
if sync:
self.writer_job.wait(None, None)
self.reader_job.wait(None, None)
def _handle_incoming_response(self, chunk):
try:
event, timer = self.expected_responses.pop(chunk.transaction_id)
except KeyError:
pass
else:
if timer is not None:
timer.cancel()
event.send(chunk)
def _check_incoming_SEND(self, chunk):
if chunk.method=='SEND' and chunk.segment is None:
error = self.msrp.check_incoming_SEND_chunk(chunk)
if error is not None:
return error
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 _handle_incoming_SEND(self, chunk):
error = self._check_incoming_SEND(chunk)
if error is None:
code, comment = 200, 'OK'
else:
code, comment = error.code, error.comment
if chunk.final:
response = make_response(chunk, code, comment)
if response is not None:
self.outgoing.send((response, None))
if code==200:
self.incoming.send(chunk)
def _reader(self):
"""Wait forever for new chunks. Send the good ones to self.incoming queue.
If a response to a previously sent chunk is received, pop the corresponding
event from self.expected_responses and send the response there.
"""
try:
self.writer_job.link(self.reader_job)
try:
while self.state in ['CONNECTED', 'FLUSHING']:
chunk = self.msrp.read_chunk()
if chunk.method is None: # response
self._handle_incoming_response(chunk)
elif chunk.method=='SEND':
self._handle_incoming_SEND(chunk)
elif chunk.method=='REPORT':
self.incoming.send(chunk)
else:
response = make_response(chunk, '501', 'Method unknown')
self.outgoing.send((response, None))
except proc.LinkedExited: # writer has exited
pass
finally:
self.writer_job.unlink(self.reader_job)
self.writer_job.kill()
self.state_logger.dbg('reader: expecting responses only')
delay = time() - self.last_expected_response
if delay>=0 and self.expected_responses:
# continue read the responses until the last timeout expires
with api.timeout(delay, None):
while self.expected_responses:
chunk = self.msrp.read_chunk()
if chunk.method is None:
self._handle_incoming_response(chunk)
else:
self.state_logger.dbg('dropping incoming %r' % chunk)
# read whatever left in the queue
with api.timeout(0, None):
while self.msrp._queue:
chunk = self.msrp.read_chunk()
if chunk.method is None:
self._handle_incoming_response(chunk)
else:
self.state_logger.dbg('dropping incoming %r' % chunk)
self.state_logger.dbg('reader: done')
except ConnectionClosedErrors, ex:
self.state_logger.dbg('reader: exiting because of %r' % ex)
self.incoming.send_exception(ex)
except:
self.state_logger.dbg('reader: losing connection because of %r' % (sys.exc_info(), ))
self.incoming.send_exception(*sys.exc_info())
raise
finally:
if not self.incoming.has_error():
self.incoming.send_exception(ConnectionDone)
self.msrp.loseConnection(sync=False)
self.set_state('DONE')
def receive_chunk(self):
return self.incoming.wait()
def _writer(self):
try:
while self.state=='CONNECTED':
send_params = self.outgoing.wait()
if send_params is None:
break
self._write_chunk(*send_params)
while self.state=='FLUSHING' and self.outgoing:
send_params = self.outgoing.wait()
if send_params is not None:
self._write_chunk(*send_params)
except ConnectionClosedErrors + (proc.LinkedExited, proc.ProcExit), ex:
self.state_logger.dbg('writer: exiting because of %r' % (ex, ))
except:
self.state_logger.dbg('writer: losing connection because of %r' % (sys.exc_info(), ))
self.msrp.loseConnection(sync=False)
raise
finally:
self.set_state('CLOSING')
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)
If sending is impossible raise MSRPSessionError.
"""
if self.state != 'CONNECTED':
raise MSRPSessionError('Cannot send chunk because MSRPSession is %s' % self.state)
if self.msrp._disconnected_event.ready():
raise MSRPSessionError(str(self.msrp._disconnected_event.wait()))
self.outgoing.send((chunk, event))
def _write_chunk(self, chunk, event=None):
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() will switch the greenlets,
# let's setup response's event and timer before write() call, just in case
event_and_timer = [event, None]
self.expected_responses[id] = event_and_timer
try:
self.msrp.write(chunk.encode())
except Exception:
if event is not None:
self.expected_responses.pop(id, None)
raise
else:
if event is not None:
timeout_error = Response408Timeout if chunk.failure_report=='yes' else Response200OK
timer = api.get_hub().schedule_call_global(self.RESPONSE_TIMEOUT, self._response_timeout, id, timeout_error)
self.last_expected_response = time() + self.RESPONSE_TIMEOUT
event_and_timer[1] = timer
def _response_timeout(self, id, timeout_error):
event, timer = self.expected_responses.pop(id, (None, None))
if event is not None:
event.send(timeout_error)
if timer is not None:
timer.cancel()
def deliver_chunk(self, chunk, event=None):
"""Send chunk, return the transaction response.
Return None immediatelly if chunk's Failure-Report is 'no'.
"""
if chunk.failure_report!='no' and event is None:
event = coros.event()
self.send_chunk(chunk, event)
if event is not None:
return event.wait()
def make_message(self, msg, content_type, failure_report=None, success_report=None):
chunk = self.msrp.make_chunk(data=msg)
chunk.add_header(protocol.ContentTypeHeader(content_type))
if failure_report is not None:
chunk.add_header(protocol.FailureReportHeader(failure_report))
if success_report is not None:
chunk.add_header(protocol.SuccessReportHeader(success_report))
return chunk
def send_message(self, msg, content_type):
chunk = self.make_message(msg, content_type)
self.send_chunk(chunk)
return chunk
def deliver_message(self, msg, content_type):
chunk = self.make_message(msg, content_type)
self.deliver_chunk(chunk)
return chunk
# TODO:
# 413 - requires special action both in reader and in writer
# continuation: #
# All MSRP endpoints MUST be able to receive the multipart/mixed [15] and multipart/alternative [15] media-types.

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