class PTCProtocol(object):
def __init__(self, alpha, beta, delay, dropChance, wait):
self.state = CLOSED
self.control_block = None
self.packet_builder = PacketBuilder()
self.socket = Soquete()
self.rcv_wnd = RECEIVE_BUFFER_SIZE
self.iss = self.compute_iss()
self.rqueue = RetransmissionQueue()
self.read_stream_open = True
self.write_stream_open = True
self.rto_estimator = RTOEstimator(self, alpha, beta, delay, dropChance)
self.packet_handler = IncomingPacketHandler(self)
self.delay = delay
self.dropChance = dropChance
self.wait = wait
self.ticks = 0
self.retransmissions = 0
self.close_mode = NO_WAIT
self.close_event = threading.Event()
self.initialize_threads()
self.initialize_timers()
def initialize_threads(self):
self.packet_sender = PacketSender(self)
self.packet_receiver = PacketReceiver(self)
self.clock = Clock(self)
def initialize_timers(self):
self.retransmission_timer = RetransmissionTimer(self)
def start_threads(self):
self.packet_receiver.start()
self.packet_sender.start()
self.clock.start()
def stop_threads(self):
self.packet_receiver.stop()
self.packet_sender.stop()
self.packet_sender.notify()
self.clock.stop()
def join_threads(self):
self.packet_receiver.join()
self.packet_sender.join()
self.clock.join()
def set_state(self, state):
self.state = state
if state == CLOSED or\
(self.close_mode == NO_WAIT and state == FIN_WAIT2):
# Señalizar este evento cuando la conexión queda completamente
# cerrada o bien cuando el usuario del socket explícitamente
# eligió esperar a que el interlocutor también cierre. Por
# defecto, el comportamiento es similar al de TCP (i.e., cierre
# asimétrico).
self.close_event.set()
if state == ESTABLISHED:
self.connected_event.set()
def compute_iss(self):
value = random.randint(0, MAX_SEQ/2)
return SequenceNumber(value)
def initialize_control_block_from(self, packet):
# +1 dado que el SYN se secuencia.
receive_seq = 1 + packet.get_seq_number()
send_seq = 1 + self.iss
send_window = packet.get_window_size()
receive_window = self.rcv_wnd
self.control_block = PTCControlBlock(send_seq, receive_seq,
send_window, receive_window)
def is_connected(self):
connected_states = [ESTABLISHED, FIN_WAIT1, FIN_WAIT2, CLOSE_WAIT,
CLOSING, LAST_ACK]
return self.state in connected_states
def build_packet(self, seq=None, ack=None, payload=None, flags=None,
window=None):
if seq is None:
seq = self.control_block.get_snd_nxt()
if flags is None:
flags = [ACKFlag]
if ack is None and ACKFlag in flags:
ack = self.control_block.get_rcv_nxt()
if window is None:
window = self.control_block.get_rcv_wnd()
packet = self.packet_builder.build(payload=payload, flags=flags,
seq=seq, ack=ack, window=window)
return packet
def send_and_queue(self, packet, is_retransmission=False):
if is_retransmission:
# Algoritmo de Karn: no usar paquetes retransmitidos para
# actualizar las estimaciones del RTO.
if self.rto_estimator.is_tracking_packets():
tracked_packet = self.rto_estimator.get_tracked_packet()
tracked_seq = tracked_packet.get_seq_number()
if tracked_seq == packet.get_seq_number():
self.rto_estimator.untrack()
else:
# Sólo se hará seguimiento de paquetes frescos para estimar el
# RTT (otra vez por el algoritmo de Karn).
if not self.rto_estimator.is_tracking_packets():
self.rto_estimator.track(packet)
# Encolar este paquete fresco para eventuales retransmisiones.
# Las retransmisiones no se reencolan pues quedan al principio de
# la cola hasta que son correctamente reconocidas.
self.rqueue.put(packet)
if not self.retransmission_timer.is_running():
# Usar la estimación actual del RTO para medir este paquete.
current_rto = self.rto_estimator.get_current_rto()
self.retransmission_timer.start(current_rto)
if self.wait and self.state == ESTABLISHED:
if random.randint(0, 100) >= self.dropChance:
time.sleep(self.delay * CLOCK_TICK)
self.socket.send(packet)
else:
print '#DROP!'
else:
self.socket.send(packet)
def set_destination_on_packet_builder(self, address, port):
self.packet_builder.set_destination_address(address)
self.packet_builder.set_destination_port(port)
def bind(self, address, port):
self.socket.bind(address, port)
self.packet_builder.set_source_address(address)
self.packet_builder.set_source_port(port)
def listen(self):
self.set_state(LISTEN)
def connect_to(self, address, port):
self.connected_event = threading.Event()
self.set_destination_on_packet_builder(address, port)
self.start_threads()
syn_packet = self.build_packet(seq=self.iss, flags=[SYNFlag],
window=self.rcv_wnd)
self.set_state(SYN_SENT)
self.send_and_queue(syn_packet)
self.connected_event.wait()
def accept(self):
if self.state != LISTEN:
raise PTCError('should listen first')
self.connected_event = threading.Event()
self.start_threads()
# Esperar hasta que un cliente desee conectarse.
self.connected_event.wait()
def send(self, data):
with self.control_block:
if not self.write_stream_open:
raise PTCError('write stream is closed')
self.control_block.to_out_buffer(data)
self.packet_sender.notify()
def receive(self, size):
data = self.control_block.from_in_buffer(size)
updated_rcv_wnd = self.control_block.get_rcv_wnd()
if updated_rcv_wnd > 0:
wnd_packet = self.build_packet(window=updated_rcv_wnd)
if self.wait:
time.sleep(self.delay * CLOCK_TICK)
self.socket.send(wnd_packet)
return data
def get_ticks(self):
return self.ticks
def tick(self):
self.ticks += 1
self.retransmission_timer.tick()
def acknowledge_packets_and_update_timers_with(self, packet):
ack_number = packet.get_ack_number()
if self.control_block.ack_is_accepted(ack_number):
# Primero, pasar este paquete al estimador de RTO para que pueda
# actualizar sus valores si corresponde (esto es, si el paquete
# está reconociendo el paquete al que está haciendo seguimiento).
self.rto_estimator.process_ack(packet)
# Luego, desencolar paquetes para retransmitir y parar/reiniciar
# el timer de retransmisiones según corresponda.
self.remove_from_retransmission_queue_packets_acked_by(packet)
def remove_from_retransmission_queue_packets_acked_by(self, packet):
# Sólo ACKs mayores que SND_UNA y menores que SND_NXT son válidos
# en este punto.
with self.rqueue:
snd_una = self.control_block.get_snd_una()
snd_nxt = self.control_block.get_snd_nxt()
# Ver qué paquetes encolados son totalmente reconocidos por
# este paquete. Necesitamos SND_UNA y SND_NXT para poder
# comparar correctamente los SEQs y ACKs.
removed_packets = self.rqueue.remove_acknowledged_by(packet,
snd_una,
snd_nxt)
if len(removed_packets) > 0:
# Algunos paquetes se reconocieron, por lo que debemos
# actualizar el timer de retransmisiones.
self.adjust_retransmission_timer()
def adjust_retransmission_timer(self):
# Comenzar con cero retransmisiones para el próximo paquete.
self.retransmissions = 0
if self.rqueue.empty():
# Todos los datos salientes quedaron reconocidos. Detener el timer.
self.retransmission_timer.stop()
else:
# Algunos datos se reconocieron pero otros aún quedan.
# Reiniciar el timer usando la estimación actual del RTO.
current_rto = self.rto_estimator.get_current_rto()
self.retransmission_timer.restart(current_rto)
def handle_outgoing(self):
if self.control_block is None:
# Cuando la conexión todavía no fue establecida, no tenemos nada
# para enviar.
return
with self.control_block:
# Analizar primero si tenemos un timeout de un paquete enviado.
if self.retransmission_timer.has_expired() and\
not self.rqueue.empty():
# Si alcanzamos el máximo número permitido de retransmisiones,
# liberar la conexión.
if self.retransmissions >= MAX_RETRANSMISSION_ATTEMPTS:
self.free()
return
# Limpiar la estimación del RTT si se hizo back-off reiteradas
# veces. Posiblemente ya no represente el RTT real.
if self.retransmissions > BOGUS_RTT_RETRANSMISSIONS:
self.rto_estimator.clear_rtt()
self.retransmissions += 1
# Hacer back-off del RTO y luego retransmitir el paquete más
# viejo que aún no fue reconocido.
self.rto_estimator.back_off_rto()
packet = self.rqueue.head()
self.send_and_queue(packet, is_retransmission=True)
if self.write_stream_open or \
self.control_block.has_data_to_send():
self.attempt_to_send_data()
else:
# Mandar FIN cuando:
# * El stream de escritura está cerrado,
# * El estado es ESTABLISHED/CLOSE_WAIT
# (i.e., todavía no se ha enviado un FIN), y
# * Todo byte saliente fue exitosamente reconocido.
self.attempt_to_send_FIN()
def attempt_to_send_data(self):
window_closed = False
while self.control_block.has_data_to_send() and not window_closed:
seq_number = self.control_block.get_snd_nxt()
to_send = self.control_block.extract_from_out_buffer(MSS)
if not to_send:
# El bloque de control no devolvió nada, lo cual es un indicio
# de que la ventana está cerrada. Luego, no tenemos nada más
# por hacer hasta que lleguen los próximos ACKs.
window_closed = True
else:
packet = self.build_packet(payload=to_send, seq=seq_number)
self.send_and_queue(packet)
def attempt_to_send_FIN(self):
state_allows_closing = self.state in [ESTABLISHED, CLOSE_WAIT]
if state_allows_closing and self.rqueue.empty():
fin_packet = self.build_packet(flags=[ACKFlag, FINFlag])
# Estamos enviando un FIN, y este flag se secuencia. Incrementar el
# siguiente byte a enviar.
self.control_block.increment_snd_nxt()
new_state = FIN_WAIT1 if self.state == ESTABLISHED else LAST_ACK
self.set_state(new_state)
self.send_and_queue(fin_packet)
def handle_incoming(self, packet):
self.packet_handler.handle(packet)
self.packet_sender.notify()
def shutdown(self, how):
if how == SHUT_RD:
self.shutdown_read_stream()
elif how == SHUT_WR:
self.shutdown_write_stream()
else:
self.shutdown_read_stream()
self.shutdown_write_stream()
def shutdown_read_stream(self):
self.read_stream_open = False
def shutdown_write_stream(self):
self.write_stream_open = False
self.packet_sender.notify()
def close(self, mode=NO_WAIT):
self.close_mode = mode
if self.state != CLOSED:
self.shutdown(SHUT_RDWR)
self.close_event.wait()
self.free()
self.join_threads()
def free(self):
if self.control_block is not None:
self.control_block.flush_buffers()
self.stop_threads()
# En caso de que el establecimiento de conexión haya fallado, esto
# destrabará al thread principal de la aplicación.
self.connected_event.set()
# Y, análogamente, esto destrabará al thread principal si se llama a
# close y free es luego invocada por algún otro thread.
self.close_event.set()
self.set_state(CLOSED)
class PTCProtocol(object):
def __init__(self):
self.state = CLOSED
self.control_block = None
self.packet_builder = PacketBuilder()
self.socket = Soquete()
self.rcv_wnd = RECEIVE_BUFFER_SIZE
self.iss = self.compute_iss()
self.rqueue = RetransmissionQueue()
self.read_stream_open = True
self.write_stream_open = True
self.packet_handler = IncomingPacketHandler(self)
self.rto_estimator = RTOEstimator(self)
self.ticks = 0
self.retransmissions = 0
self.close_mode = NO_WAIT
self.close_event = threading.Event()
self.initialize_threads()
self.initialize_timers()
def initialize_threads(self):
self.packet_sender = PacketSender(self)
self.packet_receiver = PacketReceiver(self)
self.clock = Clock(self)
def initialize_timers(self):
self.retransmission_timer = RetransmissionTimer(self)
def start_threads(self):
self.packet_receiver.start()
self.packet_sender.start()
self.clock.start()
def stop_threads(self):
self.packet_receiver.stop()
self.packet_sender.stop()
self.packet_sender.notify()
self.clock.stop()
def join_threads(self):
self.packet_receiver.join()
self.packet_sender.join()
self.clock.join()
def set_state(self, state):
self.state = state
if state == CLOSED or\
(self.close_mode == NO_WAIT and state == FIN_WAIT2):
# Signal this event when the connection is completely closed or
# otherwise if the user explicitly chose to wait for the other
# party to close also. By default, this behavior resembles TCP
# (i.e., asymmetric close).
self.close_event.set()
if state == ESTABLISHED:
self.connected_event.set()
def compute_iss(self):
value = random.randint(0, MAX_SEQ)
return SequenceNumber(value)
def initialize_control_block_from(self, packet):
# +1 since the SYN flag is also sequenced.
receive_seq = 1 + packet.get_seq_number()
send_seq = 1 + self.iss
send_window = packet.get_window_size()
receive_window = self.rcv_wnd
self.control_block = PTCControlBlock(send_seq, receive_seq,
send_window, receive_window)
def is_connected(self):
connected_states = [ESTABLISHED, FIN_WAIT1, FIN_WAIT2, CLOSE_WAIT,
CLOSING, LAST_ACK]
return self.state in connected_states
def build_packet(self, seq=None, ack=None, payload=None, flags=None,
window=None):
if seq is None:
seq = self.control_block.get_snd_nxt()
if flags is None:
flags = [ACKFlag]
if ack is None and ACKFlag in flags:
ack = self.control_block.get_rcv_nxt()
if window is None:
window = self.control_block.get_rcv_wnd()
packet = self.packet_builder.build(payload=payload, flags=flags,
seq=seq, ack=ack, window=window)
return packet
def send_and_queue(self, packet, is_retransmission=False):
if is_retransmission:
# Karn's algorithm: do not use retransmitted packets to update
# RTO estimations.
if self.rto_estimator.is_tracking_packets():
tracked_packet = self.rto_estimator.get_tracked_packet()
tracked_seq = tracked_packet.get_seq_number()
if tracked_seq == packet.get_seq_number():
self.rto_estimator.untrack()
else:
# Only fresh packets will be tracked for their RTTs (Karn's
# algorithm once more).
if not self.rto_estimator.is_tracking_packets():
self.rto_estimator.track(packet)
# Enqueue this fresh packet for eventual retransmissions.
# Retransmissions are not re-enqueued since they remain at the
# head of the queue until they are acknowledged.
self.rqueue.put(packet)
if not self.retransmission_timer.is_running():
# Use current RTO estimation to time this packet.
current_rto = self.rto_estimator.get_current_rto()
self.retransmission_timer.start(current_rto)
self.socket.send(packet)
def set_destination_on_packet_builder(self, address, port):
self.packet_builder.set_destination_address(address)
self.packet_builder.set_destination_port(port)
def bind(self, address, port):
self.socket.bind(address, port)
self.packet_builder.set_source_address(address)
self.packet_builder.set_source_port(port)
def listen(self):
self.set_state(LISTEN)
def connect_to(self, address, port):
self.connected_event = threading.Event()
self.set_destination_on_packet_builder(address, port)
self.start_threads()
syn_packet = self.build_packet(seq=self.iss, flags=[SYNFlag],
window=self.rcv_wnd)
self.set_state(SYN_SENT)
self.send_and_queue(syn_packet)
self.connected_event.wait()
def accept(self):
if self.state != LISTEN:
raise PTCError('should listen first')
self.connected_event = threading.Event()
self.start_threads()
# Wait until client attempts to connect.
self.connected_event.wait()
def send(self, data):
with self.control_block:
if not self.write_stream_open:
raise PTCError('write stream is closed')
self.control_block.to_out_buffer(data)
self.packet_sender.notify()
def receive(self, size):
data = self.control_block.from_in_buffer(size)
updated_rcv_wnd = self.control_block.get_rcv_wnd()
if updated_rcv_wnd > 0:
wnd_packet = self.build_packet(window=updated_rcv_wnd)
self.socket.send(wnd_packet)
return data
def get_ticks(self):
return self.ticks
def tick(self):
self.ticks += 1
self.retransmission_timer.tick()
def acknowledge_packets_and_update_timers_with(self, packet):
ack_number = packet.get_ack_number()
if self.control_block.ack_is_accepted(ack_number):
# First, pass this packet to the RTO estimator in order to update
# its values if appropriate (that is, if the packet is acknowledging
# the packet tracked by it).
self.rto_estimator.process_ack(packet)
# Then, remove enqueued packets and stop/restart the retransmission
# timer as required.
self.remove_from_retransmission_queue_packets_acked_by(packet)
def remove_from_retransmission_queue_packets_acked_by(self, packet):
# Only ACK numbers greater than SND_UNA and less than SND_NXT are
# valid here.
with self.rqueue:
snd_una = self.control_block.get_snd_una()
snd_nxt = self.control_block.get_snd_nxt()
# See which packets already enqueued are acknowledged by this
# packet. SND_UNA and SND_NXT are needed for properly comparing
# SEQs and ACKs.
removed_packets = self.rqueue.remove_acknowledged_by(packet,
snd_una,
snd_nxt)
if len(removed_packets) > 0:
# Some packets were acked, and so we must update the
# retransmission timer accordingly.
self.adjust_retransmission_timer()
def adjust_retransmission_timer(self):
# Start at zero retransmissions for next packet.
self.retransmissions = 0
if self.rqueue.empty():
# All outstanding data was acknowledged. Stop timer.
self.retransmission_timer.stop()
else:
# Some data was acknowledged, but some still remains.
# Restart the timer using current RTO estimation.
current_rto = self.rto_estimator.get_current_rto()
self.retransmission_timer.restart(current_rto)
def handle_outgoing(self):
if self.control_block is None:
# When connection is still not established, we don't have
# anything to send.
return
with self.control_block:
# See first if we have a transmission timeout.
if self.retransmission_timer.has_expired() and\
not self.rqueue.empty():
# If we reached the maximum retransmissions allowed,
# release the connection.
if self.retransmissions >= MAX_RETRANSMISSION_ATTEMPTS:
self.free()
return
# Clear RTT estimation; it was backed off several times and so
# it might no longer represent the actual RTT.
if self.retransmissions > BOGUS_RTT_RETRANSMISSIONS:
self.rto_estimator.clear_rtt()
self.retransmissions += 1
# Back off RTO and then retransmit the earliest packet not yet
# acknowledged.
self.rto_estimator.back_off_rto()
packet = self.rqueue.head()
self.send_and_queue(packet, is_retransmission=True)
if self.write_stream_open or \
self.control_block.has_data_to_send():
self.attempt_to_send_data()
else:
# Send FIN when:
# * Write stream is closed,
# * State is ESTABLISHED/CLOSE_WAIT
# (i.e., FIN was not yet sent), and
# * Every outgoing byte was successfully acknowledged.
self.attempt_to_send_FIN()
def attempt_to_send_data(self):
window_closed = False
while self.control_block.has_data_to_send() and not window_closed:
seq_number = self.control_block.get_snd_nxt()
to_send = self.control_block.extract_from_out_buffer(MSS)
if not to_send:
# Control block returned nothing, which hints that the window
# is closed. Thus, we have nothing else to do until further
# ACKs arrive.
window_closed = True
else:
packet = self.build_packet(payload=to_send, seq=seq_number)
self.send_and_queue(packet)
def attempt_to_send_FIN(self):
state_allows_closing = self.state in [ESTABLISHED, CLOSE_WAIT]
if state_allows_closing and self.rqueue.empty():
fin_packet = self.build_packet(flags=[ACKFlag, FINFlag])
# We are sending a FIN packet, and this flag is sequenced. Move
# forward the next byte sequence to be sent.
self.control_block.increment_snd_nxt()
new_state = FIN_WAIT1 if self.state == ESTABLISHED else LAST_ACK
self.set_state(new_state)
self.send_and_queue(fin_packet)
def handle_incoming(self, packet):
self.packet_handler.handle(packet)
self.packet_sender.notify()
def shutdown(self, how):
if how == SHUT_RD:
self.shutdown_read_stream()
elif how == SHUT_WR:
self.shutdown_write_stream()
else:
self.shutdown_read_stream()
self.shutdown_write_stream()
def shutdown_read_stream(self):
self.read_stream_open = False
def shutdown_write_stream(self):
self.write_stream_open = False
self.packet_sender.notify()
def close(self, mode=NO_WAIT):
self.close_mode = mode
if self.state != CLOSED:
self.shutdown(SHUT_RDWR)
self.close_event.wait()
self.free()
self.join_threads()
def free(self):
if self.control_block is not None:
self.control_block.flush_buffers()
self.stop_threads()
# In case connection establishment failed, this will unlock the main
# thread.
self.connected_event.set()
# And, similarly, this will unlock the main thread if close is called
# and free is later invoked by some other thread, for whatever reason.
self.close_event.set()
self.set_state(CLOSED)
class PTCProtocol(object):
def __init__(self, ack_delay=0, ack_loss_probability=0):
# Modificación
self.ack_delay = ack_delay
self.ack_loss_probability = ack_loss_probability
self.retransmissions = 0
logging.basicConfig(
level=logging.DEBUG,
format='%(asctime)s:%(levelname)s:%(name)s:%(message)s',
filename='ptc.log')
self.logger = logging.getLogger('PTCProtocol')
self.state = CLOSED
self.control_block = None
self.packet_builder = PacketBuilder()
self.socket = Soquete(protocol=self)
self.rcv_wnd = RECEIVE_BUFFER_SIZE
self.iss = self.compute_iss()
self.rqueue = RetransmissionQueue()
self.retransmission_attempts = dict()
self.read_stream_open = True
self.write_stream_open = True
self.packet_handler = IncomingPacketHandler(self)
self.close_event = threading.Event()
self.initialize_threads()
def initialize_threads(self):
self.packet_sender = PacketSender(self)
self.packet_receiver = PacketReceiver(self)
self.clock = Clock(self)
self.keepalive_sender = KeepAliveSender(self)
def start_threads(self):
self.packet_receiver.start()
self.packet_sender.start()
self.clock.start()
self.keepalive_sender.start()
def stop_threads(self):
self.packet_receiver.stop()
self.packet_sender.stop()
self.packet_sender.notify()
self.clock.stop()
self.keepalive_sender.stop()
def join_threads(self):
self.packet_receiver.join()
self.packet_sender.join()
self.clock.join()
self.keepalive_sender.join()
def set_state(self, state):
self.state = state
if state == CLOSED or state == FIN_WAIT2:
self.close_event.set()
if state == ESTABLISHED:
self.connected_event.set()
def compute_iss(self):
value = random.randint(0, MAX_SEQ)
return SequenceNumber(value)
def initialize_control_block_from(self, packet):
# +1 dado que el SYN se secuencia.
receive_seq = 1 + packet.get_seq_number()
send_seq = 1 + self.iss
send_window = packet.get_window_size()
receive_window = self.rcv_wnd
self.control_block = PTCControlBlock(send_seq, receive_seq,
send_window, receive_window)
def is_connected(self):
connected_states = [
ESTABLISHED, FIN_WAIT1, FIN_WAIT2, CLOSE_WAIT, CLOSING, LAST_ACK
]
return self.state in connected_states
def build_packet(self,
seq=None,
ack=None,
payload=None,
flags=None,
window=None):
if seq is None:
seq = self.control_block.get_snd_nxt()
if flags is None:
flags = [ACKFlag]
if ack is None and ACKFlag in flags:
ack = self.control_block.get_rcv_nxt()
if window is None:
window = self.control_block.get_rcv_wnd()
packet = self.packet_builder.build(payload=payload,
flags=flags,
seq=seq,
ack=ack,
window=window)
return packet
def send_and_queue(self, packet):
self.rqueue.put(packet)
self.socket.send(packet)
def set_destination_on_packet_builder(self, address, port):
self.packet_builder.set_destination_address(address)
self.packet_builder.set_destination_port(port)
def bind(self, address, port):
self.socket.bind(address, port)
self.packet_builder.set_source_address(address)
self.packet_builder.set_source_port(port)
def listen(self):
self.set_state(LISTEN)
def connect_to(self, address, port):
self.connected_event = threading.Event()
self.set_destination_on_packet_builder(address, port)
self.start_threads()
syn_packet = self.build_packet(seq=self.iss,
flags=[SYNFlag],
window=self.rcv_wnd)
self.set_state(SYN_SENT)
self.send_and_queue(syn_packet)
self.connected_event.wait()
def accept(self):
if self.state != LISTEN:
raise PTCError('should listen first')
self.connected_event = threading.Event()
self.start_threads()
# Esperar hasta que un cliente desee conectarse.
self.connected_event.wait()
def send(self, data):
with self.control_block:
if not self.write_stream_open:
raise PTCError('write stream is closed')
self.control_block.to_out_buffer(data)
self.packet_sender.notify()
def receive(self, size):
data = self.control_block.from_in_buffer(size)
updated_rcv_wnd = self.control_block.get_rcv_wnd()
if updated_rcv_wnd > 0:
wnd_packet = self.build_packet(window=updated_rcv_wnd)
self.logger.debug('Enviando window: window=%d' % updated_rcv_wnd)
self.socket.send(wnd_packet)
return data
def tick(self):
with self.rqueue:
self.rqueue.tick()
self.retransmit_packets_if_needed()
def send_keepalive(self):
rcv_wnd = self.control_block.get_rcv_wnd()
packet = self.build_packet(window=rcv_wnd)
self.logger.debug('Enviando keepalive: window=%d' % rcv_wnd)
self.socket.send(packet)
def retransmit_packets_if_needed(self):
to_retransmit = self.rqueue.get_packets_to_retransmit()
for packet in to_retransmit:
attempts = self.update_retransmission_attempts_for(packet)
self.logger.debug('Retransmitiendo: intento %d' % attempts)
if attempts > MAX_RETRANSMISSION_ATTEMPTS:
self.logger.debug('Límite de retransmisiones alcanzado')
# Nos damos por vencidos. Se superó el máximo número de
# retransmisiones para este paquete.
self.free()
else:
self.retransmissions += 1
self.send_and_queue(packet)
def update_retransmission_attempts_for(self, packet):
seq_number = packet.get_seq_number()
attempts = 1 + self.retransmission_attempts.setdefault(seq_number, 0)
self.retransmission_attempts[seq_number] = attempts
return attempts
def acknowledge_packets_on_retransmission_queue_with(self, packet):
ack_number = packet.get_ack_number()
if self.control_block.ack_is_accepted(ack_number):
# Sólo ACKs mayores que SND_UNA y menores que SND_NXT son válidos
# en este punto.
with self.rqueue:
snd_una = self.control_block.get_snd_una()
snd_nxt = self.control_block.get_snd_nxt()
# Ver qué paquetes encolados son totalmente reconocidos por
# este paquete. Necesitamos SND_UNA y SND_NXT para poder
# comparar correctamente los SEQs y ACKs.
removed_packets = self.rqueue.remove_acknowledged_by(
packet, snd_una, snd_nxt)
for removed_packet in removed_packets:
seq_number = removed_packet.get_seq_number()
if seq_number in self.retransmission_attempts:
del self.retransmission_attempts[seq_number]
def handle_outgoing(self):
if self.control_block is None:
# Cuando la conexión todavía no fue establecida, no tenemos nada
# para enviar.
return
with self.control_block:
if self.write_stream_open or self.control_block.has_data_to_send():
self.attempt_to_send_data()
else:
# Mandar FIN cuando:
# * El stream de escritura está cerrado,
# * El estado es ESTABLISHED/CLOSE_WAIT
# (i.e., todavía no se ha enviado un FIN), y
# * Todo byte saliente fue exitosamente reconocido.
self.attempt_to_send_FIN()
def attempt_to_send_data(self):
window_closed = False
while self.control_block.has_data_to_send() and not window_closed:
seq_number = self.control_block.get_snd_nxt()
to_send = self.control_block.extract_from_out_buffer(MSS)
if not to_send:
# El bloque de control no devolvió nada, lo cual es un indicio
# de que la ventana está cerrada. Luego, no tenemos nada más
# por hacer hasta que lleguen los próximos ACKs.
window_closed = True
else:
packet = self.build_packet(payload=to_send, seq=seq_number)
self.send_and_queue(packet)
def attempt_to_send_FIN(self):
state_allows_closing = self.state in [ESTABLISHED, CLOSE_WAIT]
if state_allows_closing and self.rqueue.empty():
fin_packet = self.build_packet(flags=[ACKFlag, FINFlag])
# Estamos enviando un FIN, y este flag se secuencia. Incrementar el
# siguiente byte a enviar.
self.control_block.increment_snd_nxt()
new_state = FIN_WAIT1 if self.state == ESTABLISHED else LAST_ACK
self.set_state(new_state)
self.send_and_queue(fin_packet)
def handle_incoming(self, packet):
self.packet_handler.handle(packet)
self.packet_sender.notify()
def shutdown(self, how):
if how == SHUT_RD:
self.shutdown_read_stream()
elif how == SHUT_WR:
self.shutdown_write_stream()
else:
self.shutdown_read_stream()
self.shutdown_write_stream()
def shutdown_read_stream(self):
self.read_stream_open = False
def shutdown_write_stream(self):
self.write_stream_open = False
self.packet_sender.notify()
def close(self):
if self.state != CLOSED:
self.shutdown(SHUT_RDWR)
self.close_event.wait()
self.free()
self.join_threads()
def free(self):
if self.control_block is not None:
self.control_block.flush_buffers()
self.stop_threads()
# En caso de que el establecimiento de conexión haya fallado, esto
# destrabará al thread principal de la aplicación.
self.connected_event.set()
# Y, análogamente, esto destrabará al thread principal si se llama a
# close y free es luego invocada por algún otro thread.
self.close_event.set()
self.set_state(CLOSED)
class PTCProtocol(object):
def __init__(self, ack_delay=0, ack_loss_probability=0):
# Modificación
self.ack_delay = ack_delay
self.ack_loss_probability = ack_loss_probability
self.retransmissions = 0
logging.basicConfig(level=logging.DEBUG,
format='%(asctime)s:%(levelname)s:%(name)s:%(message)s',
filename='ptc.log')
self.logger = logging.getLogger('PTCProtocol')
self.state = CLOSED
self.control_block = None
self.packet_builder = PacketBuilder()
self.socket = Soquete(protocol=self)
self.rcv_wnd = RECEIVE_BUFFER_SIZE
self.iss = self.compute_iss()
self.rqueue = RetransmissionQueue()
self.retransmission_attempts = dict()
self.read_stream_open = True
self.write_stream_open = True
self.packet_handler = IncomingPacketHandler(self)
self.close_event = threading.Event()
self.initialize_threads()
def initialize_threads(self):
self.packet_sender = PacketSender(self)
self.packet_receiver = PacketReceiver(self)
self.clock = Clock(self)
self.keepalive_sender = KeepAliveSender(self)
def start_threads(self):
self.packet_receiver.start()
self.packet_sender.start()
self.clock.start()
self.keepalive_sender.start()
def stop_threads(self):
self.packet_receiver.stop()
self.packet_sender.stop()
self.packet_sender.notify()
self.clock.stop()
self.keepalive_sender.stop()
def join_threads(self):
self.packet_receiver.join()
self.packet_sender.join()
self.clock.join()
self.keepalive_sender.join()
def set_state(self, state):
self.state = state
if state == CLOSED or state == FIN_WAIT2:
self.close_event.set()
if state == ESTABLISHED:
self.connected_event.set()
def compute_iss(self):
value = random.randint(0, MAX_SEQ)
return SequenceNumber(value)
def initialize_control_block_from(self, packet):
# +1 dado que el SYN se secuencia.
receive_seq = 1 + packet.get_seq_number()
send_seq = 1 + self.iss
send_window = packet.get_window_size()
receive_window = self.rcv_wnd
self.control_block = PTCControlBlock(send_seq, receive_seq,
send_window, receive_window)
def is_connected(self):
connected_states = [ESTABLISHED, FIN_WAIT1, FIN_WAIT2, CLOSE_WAIT,
CLOSING, LAST_ACK]
return self.state in connected_states
def build_packet(self, seq=None, ack=None, payload=None, flags=None,
window=None):
if seq is None:
seq = self.control_block.get_snd_nxt()
if flags is None:
flags = [ACKFlag]
if ack is None and ACKFlag in flags:
ack = self.control_block.get_rcv_nxt()
if window is None:
window = self.control_block.get_rcv_wnd()
packet = self.packet_builder.build(payload=payload, flags=flags,
seq=seq, ack=ack, window=window)
return packet
def send_and_queue(self, packet):
self.rqueue.put(packet)
self.socket.send(packet)
def set_destination_on_packet_builder(self, address, port):
self.packet_builder.set_destination_address(address)
self.packet_builder.set_destination_port(port)
def bind(self, address, port):
self.socket.bind(address, port)
self.packet_builder.set_source_address(address)
self.packet_builder.set_source_port(port)
def listen(self):
self.set_state(LISTEN)
def connect_to(self, address, port):
self.connected_event = threading.Event()
self.set_destination_on_packet_builder(address, port)
self.start_threads()
syn_packet = self.build_packet(seq=self.iss, flags=[SYNFlag],
window=self.rcv_wnd)
self.set_state(SYN_SENT)
self.send_and_queue(syn_packet)
self.connected_event.wait()
def accept(self):
if self.state != LISTEN:
raise PTCError('should listen first')
self.connected_event = threading.Event()
self.start_threads()
# Esperar hasta que un cliente desee conectarse.
self.connected_event.wait()
def send(self, data):
with self.control_block:
if not self.write_stream_open:
raise PTCError('write stream is closed')
self.control_block.to_out_buffer(data)
self.packet_sender.notify()
def receive(self, size):
data = self.control_block.from_in_buffer(size)
updated_rcv_wnd = self.control_block.get_rcv_wnd()
if updated_rcv_wnd > 0:
wnd_packet = self.build_packet(window=updated_rcv_wnd)
self.logger.debug('Enviando window: window=%d' % updated_rcv_wnd)
self.socket.send(wnd_packet)
return data
def tick(self):
with self.rqueue:
self.rqueue.tick()
self.retransmit_packets_if_needed()
def send_keepalive(self):
rcv_wnd = self.control_block.get_rcv_wnd()
packet = self.build_packet(window=rcv_wnd)
self.logger.debug('Enviando keepalive: window=%d' % rcv_wnd)
self.socket.send(packet)
def retransmit_packets_if_needed(self):
to_retransmit = self.rqueue.get_packets_to_retransmit()
for packet in to_retransmit:
attempts = self.update_retransmission_attempts_for(packet)
self.logger.debug('Retransmitiendo: intento %d' % attempts)
if attempts > MAX_RETRANSMISSION_ATTEMPTS:
self.logger.debug('Límite de retransmisiones alcanzado')
# Nos damos por vencidos. Se superó el máximo número de
# retransmisiones para este paquete.
self.free()
else:
self.retransmissions += 1
self.send_and_queue(packet)
def update_retransmission_attempts_for(self, packet):
seq_number = packet.get_seq_number()
attempts = 1 + self.retransmission_attempts.setdefault(seq_number, 0)
self.retransmission_attempts[seq_number] = attempts
return attempts
def acknowledge_packets_on_retransmission_queue_with(self, packet):
ack_number = packet.get_ack_number()
if self.control_block.ack_is_accepted(ack_number):
# Sólo ACKs mayores que SND_UNA y menores que SND_NXT son válidos
# en este punto.
with self.rqueue:
snd_una = self.control_block.get_snd_una()
snd_nxt = self.control_block.get_snd_nxt()
# Ver qué paquetes encolados son totalmente reconocidos por
# este paquete. Necesitamos SND_UNA y SND_NXT para poder
# comparar correctamente los SEQs y ACKs.
removed_packets = self.rqueue.remove_acknowledged_by(packet,
snd_una,
snd_nxt)
for removed_packet in removed_packets:
seq_number = removed_packet.get_seq_number()
if seq_number in self.retransmission_attempts:
del self.retransmission_attempts[seq_number]
def handle_outgoing(self):
if self.control_block is None:
# Cuando la conexión todavía no fue establecida, no tenemos nada
# para enviar.
return
with self.control_block:
if self.write_stream_open or self.control_block.has_data_to_send():
self.attempt_to_send_data()
else:
# Mandar FIN cuando:
# * El stream de escritura está cerrado,
# * El estado es ESTABLISHED/CLOSE_WAIT
# (i.e., todavía no se ha enviado un FIN), y
# * Todo byte saliente fue exitosamente reconocido.
self.attempt_to_send_FIN()
def attempt_to_send_data(self):
window_closed = False
while self.control_block.has_data_to_send() and not window_closed:
seq_number = self.control_block.get_snd_nxt()
to_send = self.control_block.extract_from_out_buffer(MSS)
if not to_send:
# El bloque de control no devolvió nada, lo cual es un indicio
# de que la ventana está cerrada. Luego, no tenemos nada más
# por hacer hasta que lleguen los próximos ACKs.
window_closed = True
else:
packet = self.build_packet(payload=to_send, seq=seq_number)
self.send_and_queue(packet)
def attempt_to_send_FIN(self):
state_allows_closing = self.state in [ESTABLISHED, CLOSE_WAIT]
if state_allows_closing and self.rqueue.empty():
fin_packet = self.build_packet(flags=[ACKFlag, FINFlag])
# Estamos enviando un FIN, y este flag se secuencia. Incrementar el
# siguiente byte a enviar.
self.control_block.increment_snd_nxt()
new_state = FIN_WAIT1 if self.state == ESTABLISHED else LAST_ACK
self.set_state(new_state)
self.send_and_queue(fin_packet)
def handle_incoming(self, packet):
self.packet_handler.handle(packet)
self.packet_sender.notify()
def shutdown(self, how):
if how == SHUT_RD:
self.shutdown_read_stream()
elif how == SHUT_WR:
self.shutdown_write_stream()
else:
self.shutdown_read_stream()
self.shutdown_write_stream()
def shutdown_read_stream(self):
self.read_stream_open = False
def shutdown_write_stream(self):
self.write_stream_open = False
self.packet_sender.notify()
def close(self):
if self.state != CLOSED:
self.shutdown(SHUT_RDWR)
self.close_event.wait()
self.free()
self.join_threads()
def free(self):
if self.control_block is not None:
self.control_block.flush_buffers()
self.stop_threads()
# En caso de que el establecimiento de conexión haya fallado, esto
# destrabará al thread principal de la aplicación.
self.connected_event.set()
# Y, análogamente, esto destrabará al thread principal si se llama a
# close y free es luego invocada por algún otro thread.
self.close_event.set()
self.set_state(CLOSED)
class PTCProtocol(object):
def __init__(self,
ack_delay=0,
ack_loss_probability=0,
packet_loss_probability=0,
alpha=0.8,
beta=0.4,
k=4,
filepath='rto.dat'):
self.ack_delay = ack_delay
self.ack_loss_probability = ack_loss_probability
print 'self.ack_loss_probability: ' + str(self.ack_loss_probability)
self.packet_loss_probability = packet_loss_probability
self.beta = beta
self.alpha = alpha
self.k = k
self.state = CLOSED
self.control_block = None
self.packet_builder = PacketBuilder()
self.socket = Soquete()
self.rcv_wnd = RECEIVE_BUFFER_SIZE
self.iss = self.compute_iss()
self.rqueue = RetransmissionQueue()
self.read_stream_open = True
self.write_stream_open = True
self.packet_handler = IncomingPacketHandler(self)
self.rto_estimator = RTOEstimator(self)
self.ticks = 0
self.retransmissions = 0
self.close_mode = NO_WAIT
self.close_event = threading.Event()
self.initialize_threads()
self.initialize_timers()
self.filepath = filepath
self.retransmission_counter = 0
def initialize_threads(self):
self.packet_sender = PacketSender(self)
self.packet_receiver = PacketReceiver(self)
self.clock = Clock(self)
def initialize_timers(self):
self.retransmission_timer = RetransmissionTimer(self)
def start_threads(self):
self.packet_receiver.start()
self.packet_sender.start()
self.clock.start()
def stop_threads(self):
self.packet_receiver.stop()
self.packet_sender.stop()
self.packet_sender.notify()
self.clock.stop()
def join_threads(self):
self.packet_receiver.join()
self.packet_sender.join()
self.clock.join()
def set_state(self, state):
self.state = state
if state == CLOSED or\
(self.close_mode == NO_WAIT and state == FIN_WAIT2):
# Señalizar este evento cuando la conexión queda completamente
# cerrada o bien cuando el usuario del socket explícitamente
# eligió esperar a que el interlocutor también cierre. Por
# defecto, el comportamiento es similar al de TCP (i.e., cierre
# asimétrico).
self.close_event.set()
if state == ESTABLISHED:
self.connected_event.set()
def compute_iss(self):
value = random.randint(0, MAX_SEQ / 2)
return SequenceNumber(value)
def initialize_control_block_from(self, packet):
# +1 dado que el SYN se secuencia.
receive_seq = 1 + packet.get_seq_number()
send_seq = 1 + self.iss
send_window = packet.get_window_size()
receive_window = self.rcv_wnd
self.control_block = PTCControlBlock(send_seq, receive_seq,
send_window, receive_window)
def is_connected(self):
connected_states = [
ESTABLISHED, FIN_WAIT1, FIN_WAIT2, CLOSE_WAIT, CLOSING, LAST_ACK
]
return self.state in connected_states
def build_packet(self,
seq=None,
ack=None,
payload=None,
flags=None,
window=None):
if seq is None:
seq = self.control_block.get_snd_nxt()
if flags is None:
flags = [ACKFlag]
if ack is None and ACKFlag in flags:
ack = self.control_block.get_rcv_nxt()
if window is None:
window = self.control_block.get_rcv_wnd()
packet = self.packet_builder.build(payload=payload,
flags=flags,
seq=seq,
ack=ack,
window=window)
return packet
def send_and_queue(self, packet, is_retransmission=False):
if is_retransmission:
self.retransmission_counter = self.retransmission_counter + 1
# Algoritmo de Karn: no usar paquetes retransmitidos para
# actualizar las estimaciones del RTO.
if self.rto_estimator.is_tracking_packets():
tracked_packet = self.rto_estimator.get_tracked_packet()
tracked_seq = tracked_packet.get_seq_number()
if tracked_seq == packet.get_seq_number():
self.rto_estimator.untrack()
else:
# Sólo se hará seguimiento de paquetes frescos para estimar el
# RTT (otra vez por el algoritmo de Karn).
if not self.rto_estimator.is_tracking_packets():
self.rto_estimator.track(packet)
# Encolar este paquete fresco para eventuales retransmisiones.
# Las retransmisiones no se reencolan pues quedan al principio de
# la cola hasta que son correctamente reconocidas.
self.rqueue.put(packet)
if not self.retransmission_timer.is_running():
# Usar la estimación actual del RTO para medir este paquete.
current_rto = self.rto_estimator.get_current_rto()
self.retransmission_timer.start(current_rto)
if self.state == ESTABLISHED and FINFlag not in packet:
if random.uniform(0, 1) < self.packet_loss_probability:
return
self.socket.send(packet)
def set_destination_on_packet_builder(self, address, port):
self.packet_builder.set_destination_address(address)
self.packet_builder.set_destination_port(port)
def bind(self, address, port):
self.socket.bind(address, port)
self.packet_builder.set_source_address(address)
self.packet_builder.set_source_port(port)
def listen(self):
self.set_state(LISTEN)
def connect_to(self, address, port):
self.connected_event = threading.Event()
self.set_destination_on_packet_builder(address, port)
self.start_threads()
syn_packet = self.build_packet(seq=self.iss,
flags=[SYNFlag],
window=self.rcv_wnd)
self.set_state(SYN_SENT)
self.send_and_queue(syn_packet)
self.connected_event.wait()
def accept(self):
if self.state != LISTEN:
raise PTCError('should listen first')
self.connected_event = threading.Event()
self.start_threads()
# Esperar hasta que un cliente desee conectarse.
self.connected_event.wait()
def send(self, data):
with self.control_block:
if not self.write_stream_open:
raise PTCError('write stream is closed')
self.control_block.to_out_buffer(data)
self.packet_sender.notify()
def receive(self, size):
data = self.control_block.from_in_buffer(size)
updated_rcv_wnd = self.control_block.get_rcv_wnd()
if updated_rcv_wnd > 0:
wnd_packet = self.build_packet(window=updated_rcv_wnd)
self.socket.send(wnd_packet)
return data
def get_ticks(self):
return self.ticks
def tick(self):
self.ticks += 1
self.retransmission_timer.tick()
def acknowledge_packets_and_update_timers_with(self, packet):
ack_number = packet.get_ack_number()
if self.control_block.ack_is_accepted(ack_number):
# Primero, pasar este paquete al estimador de RTO para que pueda
# actualizar sus valores si corresponde (esto es, si el paquete
# está reconociendo el paquete al que está haciendo seguimiento).
self.rto_estimator.process_ack(packet)
# Luego, desencolar paquetes para retransmitir y parar/reiniciar
# el timer de retransmisiones según corresponda.
self.remove_from_retransmission_queue_packets_acked_by(packet)
def remove_from_retransmission_queue_packets_acked_by(self, packet):
# Sólo ACKs mayores que SND_UNA y menores que SND_NXT son válidos
# en este punto.
with self.rqueue:
snd_una = self.control_block.get_snd_una()
snd_nxt = self.control_block.get_snd_nxt()
# Ver qué paquetes encolados son totalmente reconocidos por
# este paquete. Necesitamos SND_UNA y SND_NXT para poder
# comparar correctamente los SEQs y ACKs.
removed_packets = self.rqueue.remove_acknowledged_by(
packet, snd_una, snd_nxt)
if len(removed_packets) > 0:
# Algunos paquetes se reconocieron, por lo que debemos
# actualizar el timer de retransmisiones.
self.adjust_retransmission_timer()
def adjust_retransmission_timer(self):
# Comenzar con cero retransmisiones para el próximo paquete.
self.retransmissions = 0
if self.rqueue.empty():
# Todos los datos salientes quedaron reconocidos. Detener el timer.
self.retransmission_timer.stop()
else:
# Algunos datos se reconocieron pero otros aún quedan.
# Reiniciar el timer usando la estimación actual del RTO.
current_rto = self.rto_estimator.get_current_rto()
self.retransmission_timer.restart(current_rto)
def handle_outgoing(self):
if self.control_block is None:
# Cuando la conexión todavía no fue establecida, no tenemos nada
# para enviar.
return
with self.control_block:
# Analizar primero si tenemos un timeout de un paquete enviado.
if self.retransmission_timer.has_expired() and\
not self.rqueue.empty():
# Si alcanzamos el máximo número permitido de retransmisiones,
# liberar la conexión.
if self.retransmissions >= MAX_RETRANSMISSION_ATTEMPTS:
self.free()
return
# Limpiar la estimación del RTT si se hizo back-off reiteradas
# veces. Posiblemente ya no represente el RTT real.
if self.retransmissions > BOGUS_RTT_RETRANSMISSIONS:
self.rto_estimator.clear_rtt()
self.retransmissions += 1
# Hacer back-off del RTO y luego retransmitir el paquete más
# viejo que aún no fue reconocido.
self.rto_estimator.back_off_rto()
packet = self.rqueue.head()
self.send_and_queue(packet, is_retransmission=True)
if self.write_stream_open or \
self.control_block.has_data_to_send():
self.attempt_to_send_data()
else:
# Mandar FIN cuando:
# * El stream de escritura está cerrado,
# * El estado es ESTABLISHED/CLOSE_WAIT
# (i.e., todavía no se ha enviado un FIN), y
# * Todo byte saliente fue exitosamente reconocido.
self.attempt_to_send_FIN()
def attempt_to_send_data(self):
window_closed = False
while self.control_block.has_data_to_send() and not window_closed:
seq_number = self.control_block.get_snd_nxt()
to_send = self.control_block.extract_from_out_buffer(MSS)
if not to_send:
# El bloque de control no devolvió nada, lo cual es un indicio
# de que la ventana está cerrada. Luego, no tenemos nada más
# por hacer hasta que lleguen los próximos ACKs.
window_closed = True
else:
packet = self.build_packet(payload=to_send, seq=seq_number)
self.send_and_queue(packet)
def attempt_to_send_FIN(self):
state_allows_closing = self.state in [ESTABLISHED, CLOSE_WAIT]
if state_allows_closing and self.rqueue.empty():
fin_packet = self.build_packet(flags=[ACKFlag, FINFlag])
# Estamos enviando un FIN, y este flag se secuencia. Incrementar el
# siguiente byte a enviar.
self.control_block.increment_snd_nxt()
new_state = FIN_WAIT1 if self.state == ESTABLISHED else LAST_ACK
self.set_state(new_state)
self.send_and_queue(fin_packet)
def handle_incoming(self, packet):
self.packet_handler.handle(packet)
self.packet_sender.notify()
def shutdown(self, how):
if how == SHUT_RD:
self.shutdown_read_stream()
elif how == SHUT_WR:
self.shutdown_write_stream()
else:
self.shutdown_read_stream()
self.shutdown_write_stream()
def shutdown_read_stream(self):
self.read_stream_open = False
def shutdown_write_stream(self):
self.write_stream_open = False
self.packet_sender.notify()
def close(self, mode=NO_WAIT):
#print 'lista rto: ' + str(self.rto_estimator.rtoList)
self.close_mode = mode
if self.state != CLOSED:
self.shutdown(SHUT_RDWR)
self.close_event.wait()
self.free()
self.join_threads()
def free(self):
self.printToFileRetransmission()
#print str(self.rto_estimator.rtoList)
if self.control_block is not None:
self.control_block.flush_buffers()
self.stop_threads()
# En caso de que el establecimiento de conexión haya fallado, esto
# destrabará al thread principal de la aplicación.
self.connected_event.set()
# Y, análogamente, esto destrabará al thread principal si se llama a
# close y free es luego invocada por algún otro thread.
self.close_event.set()
self.set_state(CLOSED)
def printToFileRetransmission(self):
with open(self.filepath, 'a') as f:
f.write(
str(self.alpha) + ' ' + str(self.beta) + ' ' +
str(self.retransmission_counter))
f.write('\n')
def printToFilePacketRTT(self):
with open(self.filepath, 'a') as f:
for (acknumber, rtt) in self.rto_estimator.rttList:
print 'acknumber: ' + str(acknumber)
print 'rtt: ' + str(rtt)
f.write(str(acknumber) + ' ' + str(rtt * CLOCK_TICK))
f.write('\n')