def _pushIfExpectedSequence(self, packet):
if packet.get_sequence_number() is self._next_sequence_number:
self.ee.emit('data', packet.getPayload())
# [1] Never send packets directly!
self._packet_sender.send(Packet.createAcknowledgementPacket(packet.getSequenceNumber()))
self._nextSequenceNumber += 1
self._packets.seek()
if self._packets.hasNext():
self._pushIfExpectedSequence(self._packets.nextValue())
def _pushIfExpectedSequence(self, packet):
if packet.get_sequence_number() is self._next_sequence_number:
self.ee.emit('data', packet.getPayload())
# [1] Never send packets directly!
self._packet_sender.send(
Packet.createAcknowledgementPacket(packet.getSequenceNumber()))
self._nextSequenceNumber += 1
self._packets.seek()
if self._packets.hasNext():
self._pushIfExpectedSequence(self._packets.nextValue())
def receive(self, packet):
if self._closed:
# Since this is closed, don't do anything.
return
# Ignores packets that have a sequence number less than the next sequence
# number
if not packet.getIsSynchronize(
) and packet.getSequenceNumber() < self._sync_sequence_number:
return
if packet.getIsSynchronize() and not self._synced:
# This is the beginning of the stream.
if packet.getSequenceNumber() is self._sync_sequence_number:
self._packet_sender.send(
Packet.createAcknowledgementPacket(
packet.getSequenceNumber()))
return
# Send the packet upstream, send acknowledgement packet to end host, and
# increment the next expected packet.
self._packets.clear()
self.ee.emit('data', packet.getPayload())
self._packet_sender.send(
Packet.createAcknowledgementPacket(packet.getSequenceNumber()))
self._packets.insert(packet)
self._next_sequence_number = packet.getSequenceNumber() + 1
self._synced = True
self._sync_sequence_number = packet.getSequenceNumber()
if packet.getIsReset():
self.ee.emit('_reset')
self._synced = False
# We're done.
return
elif (packet.getIsReset()):
self.ee.emit('_reset')
self.ee._synced = False
elif not self._synced:
# If we are not synchronized with sender, then this means that we should
# wait for the end host to send a synchronization packet.
# We are done.
return
elif packet.getSequenceNumber() < self._syncSequenceNumber:
# This is a troll packet. Ignore it.
return
elif packet.getSequenceNumber() >= (
self._packets.currentValue().getSequenceNumber() +
constants.WINDOW_SIZE):
# This means that the next packet received is not within the window size.
self.ee.emit('_window_size_exceeded')
return
# This means that we should simply insert the packet. If the packet's
# sequence number is the one that we were expecting, then send it upstream,
# acknowledge the packet, and increment the next expected sequence number.
#
# Once acknowledged, check to see if there aren't any more pending packets
# after the current packet. If there are, then check to see if the next
# packet is the expected packet number. If it is, then start the
# acknowledgement process anew.
result = self._packets.insert(packet)
if result is LinkedList.InsertionResult.INSERTED:
self._pushIfExpectedSequence(packet)
elif result is LinkedList.InsertionResult.EXISTS:
self._packet_sender.send(
Packet.createAcknowledgementPacket(packet.getSequenceNumber()))
def receive(self, packet):
if self._closed:
# Since this is closed, don't do anything.
return
# Ignores packets that have a sequence number less than the next sequence
# number
if not packet.getIsSynchronize() and packet.getSequenceNumber() < self._sync_sequence_number:
return
if packet.getIsSynchronize() and not self._synced:
# This is the beginning of the stream.
if packet.getSequenceNumber() is self._sync_sequence_number:
self._packet_sender.send(Packet.createAcknowledgementPacket(packet.getSequenceNumber()))
return
# Send the packet upstream, send acknowledgement packet to end host, and
# increment the next expected packet.
self._packets.clear()
self.ee.emit('data', packet.getPayload())
self._packet_sender.send(Packet.createAcknowledgementPacket(packet.getSequenceNumber()))
self._packets.insert(packet)
self._next_sequence_number = packet.getSequenceNumber() + 1
self._synced = True
self._sync_sequence_number = packet.getSequenceNumber()
if packet.getIsReset():
self.ee.emit('_reset')
self._synced = False
# We're done.
return
elif (packet.getIsReset()):
self.ee.emit('_reset')
self.ee._synced = False
elif not self._synced:
# If we are not synchronized with sender, then this means that we should
# wait for the end host to send a synchronization packet.
# We are done.
return
elif packet.getSequenceNumber() < self._syncSequenceNumber:
# This is a troll packet. Ignore it.
return
elif packet.getSequenceNumber() >= (self._packets.currentValue().getSequenceNumber() + constants.WINDOW_SIZE):
# This means that the next packet received is not within the window size.
self.ee.emit('_window_size_exceeded')
return
# This means that we should simply insert the packet. If the packet's
# sequence number is the one that we were expecting, then send it upstream,
# acknowledge the packet, and increment the next expected sequence number.
#
# Once acknowledged, check to see if there aren't any more pending packets
# after the current packet. If there are, then check to see if the next
# packet is the expected packet number. If it is, then start the
# acknowledgement process anew.
result = self._packets.insert(packet)
if result is LinkedList.InsertionResult.INSERTED:
self._pushIfExpectedSequence(packet)
elif result is LinkedList.InsertionResult.EXISTS:
self._packet_sender.send(Packet.createAcknowledgementPacket(packet.getSequenceNumber()))
