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)
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 __init__(self, address, port):
self.retransmission_queue = RetransmissionQueue(self)
self.retransmission_attempts = dict()
self.outgoing_buffer = DataBuffer()
self.state = CLOSED
self.control_block = ClientControlBlock(address, port)
self.socket = Soquete(address, port)
self.packet_builder = PacketBuilder(self)
def __init__(self, delay=0, perdida=0):
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.retransmission_attempts = dict()
self.read_stream_open = True
self.write_stream_open = True
self.packet_handler = IncomingPacketHandler(self, delay, perdida)
self.close_event = threading.Event()
self.initialize_threads()
def __init__(self, address, port): self.retransmission_queue = RetransmissionQueue(self) self.retransmission_attempts = dict() self.outgoing_buffer = DataBuffer() self.state = CLOSED self.control_block = ClientControlBlock(address, port) self.socket = Soquete(address, port) self.packet_builder = PacketBuilder(self)
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.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 __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 __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 __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()
class PTCClientProtocol(object):
def __init__(self, address, port):
self.retransmission_queue = RetransmissionQueue(self)
self.retransmission_attempts = dict()
self.outgoing_buffer = DataBuffer()
self.state = CLOSED
self.control_block = ClientControlBlock(address, port)
self.socket = Soquete(address, port)
self.packet_builder = PacketBuilder(self)
def is_connected(self):
return self.state == ESTABLISHED
def build_packet(self, payload=None, flags=None):
seq = self.control_block.get_send_seq()
if payload is not None:
self.control_block.increment_send_seq()
packet = self.packet_builder.build(payload=payload, flags=flags, seq=seq)
return packet
def send_packet(self, packet):
self.socket.send(packet)
def send_and_queue_packet(self, packet):
self.send_packet(packet)
self.retransmission_queue.put(packet)
seq_number = packet.get_seq_number()
if seq_number in self.retransmission_attempts:
if self.retransmission_attempts[seq_number] > \
MAX_RETRANSMISSION_ATTEMPTS + 1:
self.retransmission_attempts[seq_number] = 0
else:
self.retransmission_attempts[seq_number] = 0
def send(self, data):
if not self.is_connected():
raise Exception('cannot send data: connection not established')
self.worker.send(data)
def connect_to(self, address, port):
self.worker = ClientProtocolWorker.spawn_for(self)
self.worker.start()
self.connected_event = threading.Event()
self.control_block.set_destination_address(address)
self.control_block.set_destination_port(port)
syn_packet = self.build_packet(flags=[SYNFlag])
self.send_and_queue_packet(syn_packet)
self.state = SYN_SENT
self.connected_event.wait()
def handle_timeout(self):
###################
## Completar! ##
###################
# Tener en cuenta que se debe:
# (1) Obtener los paquetes en self.retranmission_queue
# (2) Volver a enviarlos
# (3) Reencolarlos para otra eventual retransmisión
# ...y verificar que no se exceda la cantidad máxima de reenvíos!
# (hacer self.shutdown() si esto ocurre y dejar un mensaje en self.error)
packet_list = []
for packet in self.retransmission_queue:
packet_list.append(packet)
self.retransmission_queue.clear()
for packet in packet_list:
if self.retransmission_attempts[packet.get_seq_number()] \
<= MAX_RETRANSMISSION_ATTEMPTS:
packet.add_flag(RSTFlag) # Uso este flag sin utilidad para poder diferenciar retransmiciones
self.send_and_queue_packet(packet)
self.retransmission_attempts[packet.get_seq_number()] += 1
else:
self.shutdown()
self.error = 'Muchas retransmisiones, fuiste!'
print "Muchas retransmisiones, fuiste!"
def handle_pending_data(self):
more_data_pending = False
if self.control_block.send_allowed():
try:
data = self.outgoing_buffer.get(MIN_PACKET_SIZE, MAX_PACKET_SIZE)
except NotEnoughDataException:
pass
else:
packet = self.build_packet(payload=data)
self.send_and_queue_packet(packet)
if not self.outgoing_buffer.empty():
more_data_pending = True
else:
more_data_pending = True
if more_data_pending:
self.worker.signal_pending_data()
def handle_incoming(self, packet):
###################
## Completar! ##
###################
# Tener en cuenta que se debe:
# * Corroborar que el flag de ACK esté seteado
# * Distinguir el caso donde el estado es SYN_SENT
# * No olvidar de hacer self.connected_event.set() al confirmar el ACK y establecer la conexión!!!
# * Analizar si #ACK es aceptado (hablar con el bloque de control para hacer este checkeo)
# * Sacar de la cola de retransmisión los paquetes reconocidos por #ACK
# * Ajustar la ventana deslizante con #ACK
# * Tener en cuenta también el caso donde el estado es FIN_SENT
if ACKFlag in packet:
ack_number = packet.get_ack_number()
seq_number = packet.get_seq_number()
if self.state == SYN_SENT:
if ack_number == self.control_block.send_seq:
self.retransmission_queue.acknowledge(packet)
self.control_block.increment_send_seq()
self.control_block.update_send_window(ack_number)
self.state = ESTABLISHED
self.connected_event.set()
elif self.state == FIN_SENT:
if ack_number == self.control_block.send_seq:
self.retransmission_queue.acknowledge(packet)
self.state = CLOSED
else:
if self.control_block.ack_ok(ack_number):
self.retransmission_queue.acknowledge(packet)
self.control_block.update_send_window(ack_number)
def handle_close_connection(self):
if not self.outgoing_buffer.empty():
self.worker.signal_pending_data()
self.worker.signal_close_connection()
elif not self.retransmission_queue.empty():
self.worker.signal_close_connection()
else:
fin_packet = self.build_packet(flags=[FINFlag])
self.send_and_queue_packet(fin_packet)
self.state = FIN_SENT
def close(self):
if self.is_connected():
self.worker.signal_close_connection()
def shutdown(self):
self.outgoing_buffer.clear()
self.retransmission_queue.clear()
self.retransmission_attempts.clear()
self.worker.stop()
# Esto es por si falló el establecimiento de conexión (para destrabar al thread principal)
self.connected_event.set()
self.state = CLOSED
def __init__(self, address, port):
self.state = CLOSED
self.control_block = ServerControlBlock(address, port)
self.socket = Soquete(address, port)
self.packet_builder = PacketBuilder(self)
self.connection_closed_event = threading.Event()
class PTCServerProtocol(object):
def __init__(self, address, port):
self.state = CLOSED
self.control_block = ServerControlBlock(address, port)
self.socket = Soquete(address, port)
self.packet_builder = PacketBuilder(self)
self.connection_closed_event = threading.Event()
def is_connected(self):
return self.state == ESTABLISHED
def is_closed(self):
return self.state == CLOSED
def build_packet(self, flags=None):
ack = self.control_block.get_receive_seq()
packet = self.packet_builder.build(flags=flags, ack=ack)
return packet
def send_packet(self, packet):
self.socket.send(packet)
def receive(self, size):
if self.is_closed() and self.incoming_buffer.empty():
raise Exception('cannot receive: connection ended and no more pending data buffered')
elif self.incoming_buffer.empty() and not self.is_connected():
raise Exception('cannot receive: connection not established')
if size < MIN_PACKET_SIZE:
size = MIN_PACKET_SIZE
data = self.incoming_buffer.sync_get(MIN_PACKET_SIZE, size)
return data
def accept(self):
self.incoming_buffer = DataBuffer()
self.state = CLOSED
self.worker = ServerProtocolWorker.spawn_for(self)
self.worker.start()
# No hay mucho por hacer... simplemente esperar a que caiga el SYN del cliente
self.connected_event = threading.Event()
self.connected_event.wait()
def handle_incoming(self, packet):
seq_number = packet.get_seq_number()
if DEBUG: print 'recibi el paquete numero', seq_number
if SYNFlag in packet:
self.control_block.set_destination_address(packet.get_source_ip())
self.control_block.set_destination_port(packet.get_source_port())
self.control_block.set_receive_seq(seq_number)
ack_packet = self.build_packet(flags=[ACKFlag])
self.send_packet(ack_packet)
self.control_block.set_receive_seq(seq_number)
self.control_block.increment_receive_seq()
self.state = ESTABLISHED
self.connected_event.set()
if DEBUG: print 'server established'
if FINFlag in packet:
if self.control_block.accepts(seq_number):
if DEBUG: print 'server ended'
self.state = FIN_RECEIVED
self.send_ack()
self.close()
else:
data = packet.get_payload()
if DEBUG: print 'recibí un paquete con esta data:', data
if self.control_block.accepts(seq_number) and data:
self.incoming_buffer.put(data)
if self.state != FIN_RECEIVED:
self.send_ack()
self.control_block.increment_receive_seq()
def send_ack(self):
ack_packet = self.build_packet(flags=[ACKFlag])
self.send_packet(ack_packet)
def shutdown(self):
self.worker.stop()
# Esto es por si falló el establecimiento de conexión (para destrabar al thread principal)
self.connected_event.set()
def close(self):
self.state = CLOSED
self.connection_closed_event.set()
def wait_for_close(self):
self.connection_closed_event.wait()
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 PTCClientProtocol(object):
def __init__(self, address, port):
self.retransmission_queue = RetransmissionQueue(self)
self.retransmission_attempts = dict()
self.outgoing_buffer = DataBuffer()
self.state = CLOSED
self.control_block = ClientControlBlock(address, port)
self.socket = Soquete(address, port)
self.packet_builder = PacketBuilder(self)
def is_connected(self):
return self.state == ESTABLISHED
def build_packet(self, payload=None, flags=None):
seq = self.control_block.get_send_seq()
if payload is not None:
self.control_block.increment_send_seq()
packet = self.packet_builder.build(payload=payload, flags=flags, seq=seq)
return packet
def send_packet(self, packet):
self.socket.send(packet)
def send_and_queue_packet(self, packet):
self.send_packet(packet)
self.retransmission_queue.put(packet)
def send(self, data):
if not self.is_connected():
raise Exception('cannot send data: connection not established')
self.worker.send(data)
def connect_to(self, address, port):
self.worker = ClientProtocolWorker.spawn_for(self)
self.worker.start()
self.connected_event = threading.Event()
self.control_block.set_destination_address(address) # No tendria que ser el protocol block ?
self.control_block.set_destination_port(port) # No tendria que ser el protocol block ?
syn_packet = self.build_packet(flags=[SYNFlag])
self.send_and_queue_packet(syn_packet)
self.state = SYN_SENT
self.connected_event.wait()
def handle_timeout(self):
###################
## Completar! ##
###################
# Tener en cuenta que se debe:
# (1) Obtener los paquetes en self.retranmission_queue
# (2) Volver a enviarlos
# (3) Reencolarlos para otra eventual retransmisión
# ...y verificar que no se exceda la cantidad máxima de reenvíos!
# (hacer self.shutdown() si esto ocurre y dejar un mensaje en self.error)
haypaquetesret = len(self.retransmission_queue.packets()) > 0
if haypaquetesret:
print "Retransmit"
self.retransmission_queue.__iter__()
primer_paquete = self.retransmission_queue.next().get_seq_number()
if self.retransmission_attempts.get(primer_paquete,0) >= MAX_RETRANSMISSION_ATTEMPTS:
self.error = "Error muchas retransmisiones"
self.shutdown()
else:
copia_retransmission_queue = self.retransmission_queue.packets()
self.retransmission_queue.clear()
for pack in copia_retransmission_queue:
self.send_and_queue_packet(pack)
self.retransmission_attempts[pack.get_seq_number()] = self.retransmission_attempts.get(pack.get_seq_number(),0) + 1 # Le sumo uno a su cantidad de retransmisiones, inicilizandolo en cero si no existe
def handle_pending_data(self):
more_data_pending = False
if self.control_block.send_allowed():
try:
data = self.outgoing_buffer.get(MIN_PACKET_SIZE, MAX_PACKET_SIZE)
except NotEnoughDataException:
pass
else:
packet = self.build_packet(payload=data)
self.send_and_queue_packet(packet)
if not self.outgoing_buffer.empty():
more_data_pending = True
else:
more_data_pending = True
if more_data_pending:
self.worker.signal_pending_data()
def handle_incoming(self, packet):
###################
## Completar! ##
###################
# Tener en cuenta que se debe:
# * Corroborar que el flag de ACK esté seteado
# * Distinguir el caso donde el estado es SYN_SENT
# * No olvidar de hacer self.connected_event.set() al confirmar el ACK y establecer la conexión!!!
# * Analizar si #ACK es aceptado (hablar con el bloque de control para hacer este checkeo)
# * Sacar de la cola de retransmisión los paquetes reconocidos por #ACK
# * Ajustar la ventana deslizante con #ACK
# * Tener en cuenta también el caso donde el estado es FIN_SENT
ack_num = packet.get_ack_number()
if ACKFlag in packet and self.control_block.valid_ack(ack_num): # si hay ack y es valido
self.retransmission_queue.acknowledge(packet) # lo sacamos del retransmission queue
self.control_block.update_window(ack_num) # actualizamos la ventana
for packs_ack in range(self.control_block.get_window_lo(),ack_num+1): # Eliminamos los paquetes ackeados del diccionario de intentos de retransmision
del retransmission_attempts[packs_ack]
if self.state == SYN_SENT: # Si estaba desconectado, conectate
self.state = ESTABLISHED
self.connected_event.set()
elif self.state == FIN_SENT: # Si te reconoce el fin de la conexion, terminala
self.state = CLOSED
self.retransmission_queue.clear()
self.retransmission_attempts.clear()
self.close()
#~ if self.outgoing_buffer and self.retransmission_queue.empty(): # Si recibimos el ack de lo ultimo imprimimos cuanto tardo
#~ print clock() - start_time
def handle_close_connection(self):
if not self.outgoing_buffer.empty():
self.worker.signal_pending_data()
self.worker.signal_close_connection()
elif not self.retransmission_queue.empty():
self.worker.signal_close_connection()
else:
fin_packet = self.build_packet(flags=[FINFlag])
self.send_and_queue_packet(fin_packet)
self.state = FIN_SENT
def close(self):
if self.is_connected():
self.worker.signal_close_connection()
def shutdown(self):
self.outgoing_buffer.clear()
self.retransmission_queue.clear()
self.retransmission_attempts.clear()
self.worker.stop()
# Esto es por si falló el establecimiento de conexión (para destrabar al thread principal)
self.connected_event.set()
self.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')
class PTCClientProtocol(object):
def __init__(self, address, port):
self.retransmission_queue = RetransmissionQueue(self)
self.retransmission_attempts = dict()
self.outgoing_buffer = DataBuffer()
self.state = CLOSED
self.control_block = ClientControlBlock(address, port)
self.socket = Soquete(address, port)
self.packet_builder = PacketBuilder(self)
def is_connected(self):
return self.state == ESTABLISHED
def build_packet(self, payload=None, flags=None):
seq = self.control_block.get_send_seq()
#Comente esto porque quedaba corrida la ventana de recepcion despues del connect
#if payload is not None:
# self.control_block.increment_send_seq()
self.control_block.increment_send_seq()
packet = self.packet_builder.build(payload=payload, flags=flags, seq=seq)
return packet
def send_packet(self, packet):
self.socket.send(packet)
def send_and_queue_packet(self, packet):
self.send_packet(packet)
self.retransmission_queue.put(packet)
def send(self, data):
if not self.is_connected():
raise Exception('cannot send data: connection not established')
self.worker.send(data)
def sendFile(self, nombre):
if not self.is_connected():
raise Exception('cannot send data: connection not established')
archivo = open(nombre)
line = archivo.readline()
self.worker.send(line)
archivo.close()
def connect_to(self, address, port):
self.worker = ClientProtocolWorker.spawn_for(self)
self.worker.start()
self.connected_event = threading.Event()
self.control_block.set_destination_address(address)
self.control_block.set_destination_port(port)
syn_packet = self.build_packet(flags=[SYNFlag])
self.send_and_queue_packet(syn_packet)
self.state = SYN_SENT
self.connected_event.wait()
def handle_timeout(self):
###################
## Completar! ##
###################
# Tener en cuenta que se debe:
# (1) Obtener los paquetes en self.retranmission_queue
# (2) Volver a enviarlos
# (3) Reencolarlos para otra eventual retransmisión
# ...y verificar que no se exceda la cantidad máxima de reenvíos!
# (hacer self.shutdown() si esto ocurre y dejar un mensaje en self.error)
retransmited = RetransmissionQueue(self)
shutdown = False
for packet in self.retransmission_queue:
seqNum = packet.get_seq_number()
retransmitions = 0
if(self.retransmission_attempts.has_key(seqNum)):
retransmitions = self.retransmission_attempts[seqNum]
if(retransmitions == MAX_RETRANSMISSION_ATTEMPTS):
shutdown = True
break
else:
self.send_packet(packet)
retransmited.put(packet)
self.retransmission_attempts[seqNum] = retransmitions + 1
if(shutdown):
self.shutdown()
else:
self.retransmission_queue = retransmited
def handle_pending_data(self):
more_data_pending = False
if self.control_block.send_allowed():
try:
data = self.outgoing_buffer.get(MIN_PACKET_SIZE, MAX_PACKET_SIZE)
except NotEnoughDataException:
pass
else:
packet = self.build_packet(payload=data)
self.send_and_queue_packet(packet)
if not self.outgoing_buffer.empty():
more_data_pending = True
else:
more_data_pending = True
if more_data_pending:
self.worker.signal_pending_data()
def handle_incoming(self, packet):
###################
## Completar! ##
###################
# Tener en cuenta que se debe:
# * Corroborar que el flag de ACK esté seteado
# * Distinguir el caso donde el estado es SYN_SENT
# * No olvidar de hacer self.connected_event.set() al confirmar el ACK y establecer la conexión!!!
# * Analizar si #ACK es aceptado (hablar con el bloque de control para hacer este checkeo)
# * Sacar de la cola de retransmisión los paquetes reconocidos por #ACK
# * Ajustar la ventana deslizante con #ACK
# * Tener en cuenta también el caso donde el estado es FIN_SENT
if not ACKFlag in packet:
print("NO ACK")
return
print("ACK "+str(packet.get_ack_number()))
if not self.control_block.ack_valid(packet.get_ack_number()):
print("NOT VALID ACK "+str(packet.get_ack_number()))
return
print("VALID ACK "+str(packet.get_ack_number()))
self.retransmission_queue.acknowledge(packet)
self.control_block.adjust_window(packet.get_ack_number())
if(self.state == SYN_SENT):
print("ESTABLISH CONNECTION")
self.state = ESTABLISHED
self.connected_event.set()
return
if(self.state == FIN_SENT):
print("CLOSE CONNECTION")
self.state = CLOSED
self.close()
def handle_close_connection(self):
if not self.outgoing_buffer.empty():
self.worker.signal_pending_data()
self.worker.signal_close_connection()
elif not self.retransmission_queue.empty():
self.worker.signal_close_connection()
else:
fin_packet = self.build_packet(flags=[FINFlag])
self.send_and_queue_packet(fin_packet)
self.state = FIN_SENT
def close(self):
if self.is_connected():
self.worker.signal_close_connection()
def shutdown(self):
self.outgoing_buffer.clear()
self.retransmission_queue.clear()
self.retransmission_attempts.clear()
self.worker.stop()
# Esto es por si falló el establecimiento de conexión (para destrabar al thread principal)
self.connected_event.set()
self.state = CLOSED
class PTCClientProtocol(object):
def __init__(self, address, port):
self.retransmission_queue = RetransmissionQueue(self)
self.retransmission_attempts = Counter()
self.outgoing_buffer = DataBuffer()
self.state = CLOSED
self.control_block = ClientControlBlock(address, port)
self.socket = Soquete(address, port)
self.packet_builder = PacketBuilder(self)
def is_connected(self):
return self.state == ESTABLISHED
def build_packet(self, payload=None, flags=None):
seq = self.control_block.get_send_seq()
if payload is not None:
self.control_block.increment_send_seq()
packet = self.packet_builder.build(payload=payload, flags=flags, seq=seq)
return packet
def send_packet(self, packet):
if DEBUG and RANDOM_LOSS:
#'perdemos' un 10% de los paquetes
if random.choice(range(10)) :
print 'mando el paquete:', packet.get_seq_number()
self.socket.send(packet)
else:
print 'Mala leche con el', packet.get_seq_number()
else:
self.socket.send(packet)
def send_and_queue_packet(self, packet):
self.send_packet(packet)
self.retransmission_queue.put(packet)
def send(self, data):
if not self.is_connected():
raise Exception('cannot send data: connection not established')
self.worker.send(data)
def connect_to(self, address, port):
self.worker = ClientProtocolWorker.spawn_for(self)
self.worker.start()
self.connected_event = threading.Event()
self.control_block.reset_numbers()
self.control_block.set_destination_address(address)
self.control_block.set_destination_port(port)
syn_packet = self.build_packet(flags=[SYNFlag])
self.send_and_queue_packet(syn_packet)
self.state = SYN_SENT
self.connected_event.wait()
def handle_timeout(self):
###################
## Completar! ##
###################
# Tener en cuenta que se debe:
# (1) Obtener los paquetes en self.retranmission_queue
# (2) Volver a enviarlos
# (3) Reencolarlos para otra eventual retransmisión
# ...y verificar que no se exceda la cantidad máxima de reenvíos!
# (hacer self.shutdown() si esto ocurre y dejar un mensaje en self.error)
# *** NO SE SI NO HABIA YA OTRA VARIABLE DONDE SE INDICABA LA CANTIDAD DE TRANSMISIONES
# *** SE CUENTA POR PAQUETE O LA COLA ENTERA?
# *** HAY QUE RETRANSMITIR TODO LO QUE ESTA EN LA COLA?
# Cantidad maxima de reenvios: MAX_RETRANSMISSION_ATTEMPTS
if DEBUG: print 'TIMEOUT'
oldQueue = self.retransmission_queue
self.retransmission_queue = RetransmissionQueue(self)
for packet in oldQueue:
if self.retransmission_attempts[packet.get_seq_number()] == MAX_RETRANSMISSION_ATTEMPTS :
self.error = 'Retransmition Limit Exceeded'
self.shutdown()
else:
self.retransmission_attempts[packet.get_seq_number()] += 1
self.send_and_queue_packet(packet)
def handle_pending_data(self):
more_data_pending = False
if self.control_block.send_allowed():
try:
data = self.outgoing_buffer.get(MIN_PACKET_SIZE, MAX_PACKET_SIZE)
except NotEnoughDataException:
pass
else:
packet = self.build_packet(payload=data)
self.send_and_queue_packet(packet)
if not self.outgoing_buffer.empty():
more_data_pending = True
else:
more_data_pending = True
if more_data_pending:
self.worker.signal_pending_data()
def handle_incoming(self, packet):
###################
## Completar! ##
###################
# Tener en cuenta que se debe:
# * Corroborar que el flag de ACK esté seteado
# * Distinguir el caso donde el estado es SYN_SENT
# * No olvidar de hacer self.connected_event.set() al confirmar el ACK y establecer la conexión!!!
# * Analizar si #ACK es aceptado (hablar con el bloque de control para hacer este checkeo)
# * Sacar de la cola de retransmisión los paquetes reconocidos por #ACK
# * Ajustar la ventana deslizante con #ACK
# * Tener en cuenta también el caso donde el estado es FIN_SENT
# Corroboro que el flag de ACK este seteado
if not ACKFlag in packet:
raise Exception('Error (hay que hacer algo mas? Es un error?)')
self.shutdown()
return
if DEBUG: print 'me llegó el paquete numero:', packet.get_ack_number()
# Reviso si el ACK es aceptado
if self.control_block.ack_accepted(packet):
# *** Si no es aceptado no hago nada no?
for ackedPacket in self.retransmission_queue.acknowledge(packet):
del(self.retransmission_attempts[ackedPacket.get_seq_number()])
self.control_block.adjust_window(packet)
else:
return
# Si fue aceptado, ejecuto accion en base al estado actual
# *** ASUMO QUE NO SE LO LLAMA SI EL ESTADO ES CLOSED, ESO ESTARA BIEN?
if self.state == ESTABLISHED:
return
elif self.state == SYN_SENT:
# El servidor establecio una conexion:
# cambio el estado del cliente y sincronizo la conexion
# Corroboro que el numero de ACK recibido sea igual al numero de SEQ enviado
ackNum = packet.get_ack_number()
seqNum = self.control_block.get_send_seq()
if not (self.control_block.modular_increment(ackNum) == seqNum):
#self.error = 'SYN_ACK inválido'
#self.shutdown()
if DEBUG: print 'recibí fruta (ack != seq):', ackNum, seqNum
#no hagamos que se cierre, tal vez le llegó algo viejo o equivocado
#dejemos que si posta anda mal, lo maten los timeouts.
return
self.state = ESTABLISHED
self.connected_event.set()
if DEBUG: print 'conexión establecida'
elif self.state == FIN_SENT:
# Recibi respuesta del servidor indicando que puedo cerrar la conexion
if DEBUG: print 'llego el fin'
self.state = CLOSED
# *** Hago algo mas para cerrar la conexion?
self.shutdown() #(?)
else:
self.error = 'Estado inexistente'
self.shutdown()
def handle_close_connection(self):
if not self.outgoing_buffer.empty():
self.worker.signal_pending_data()
self.worker.signal_close_connection()
elif not self.retransmission_queue.empty():
self.worker.signal_close_connection()
else:
fin_packet = self.build_packet(flags=[FINFlag])
self.send_and_queue_packet(fin_packet)
self.state = FIN_SENT
def close(self):
if self.is_connected():
self.worker.signal_close_connection()
def shutdown(self):
self.outgoing_buffer.clear()
self.retransmission_queue.clear()
self.retransmission_attempts.clear()
self.worker.stop()
# Esto es por si falló el establecimiento de conexión (para destrabar al thread principal)
self.connected_event.set()
self.state = CLOSED
class PTCClientProtocol(object):
def __init__(self, address, port):
self.retransmission_queue = RetransmissionQueue(self)
self.retransmission_attempts = dict()
self.outgoing_buffer = DataBuffer()
self.state = CLOSED
self.control_block = ClientControlBlock(address, port)
self.socket = Soquete(address, port)
self.packet_builder = PacketBuilder(self)
def is_connected(self):
return self.state == ESTABLISHED
def build_packet(self, payload=None, flags=None):
seq = self.control_block.get_send_seq()
#if payload is not None:
self.control_block.increment_send_seq()
packet = self.packet_builder.build(payload=payload,
flags=flags,
seq=seq)
return packet
def send_packet(self, packet):
if (debug):
print("Voy a mandar el paquete número: "),
print(str(packet.get_seq_number()))
#if random.randint(1, 11) == 1:
# simulo congestión
# return
self.socket.send(packet)
def send_and_queue_packet(self, packet):
self.send_packet(packet)
self.retransmission_queue.put(packet)
def send(self, data):
if not self.is_connected():
raise Exception('cannot send data: connection not established')
self.worker.send(data)
global t1
t1 = time.time()
def connect_to(self, address, port):
self.worker = ClientProtocolWorker.spawn_for(self)
self.worker.start()
self.connected_event = threading.Event()
self.control_block.set_destination_address(address)
self.control_block.set_destination_port(port)
syn_packet = self.build_packet(flags=[SYNFlag])
self.send_and_queue_packet(syn_packet)
self.state = SYN_SENT
self.connected_event.wait()
def handle_timeout(self):
global count_rets
count_rets += 1
if (debug or True):
print("Parece que se perdió un paquete, voy a reenviar.")
new_queue = RetransmissionQueue(self)
for packet in self.retransmission_queue:
if packet not in self.retransmission_attempts:
self.retransmission_attempts[packet.get_seq_number()] = 0
self.retransmission_attempts[packet.get_seq_number()] += 1
if self.retransmission_attempts[
packet.get_seq_number()] >= MAX_RETRANSMISSION_ATTEMPTS:
self.shutdown()
self.error = "Intentos de retransmisión superó el máximo"
break
else:
self.send_packet(packet)
new_queue.put(packet)
self.retransmission_queue = new_queue
def handle_pending_data(self):
more_data_pending = False
if self.control_block.send_allowed():
try:
data = self.outgoing_buffer.get(MIN_PACKET_SIZE,
MAX_PACKET_SIZE)
except NotEnoughDataException:
pass
else:
packet = self.build_packet(payload=data)
self.send_and_queue_packet(packet)
if not self.outgoing_buffer.empty():
more_data_pending = True
else:
more_data_pending = True
if more_data_pending:
self.worker.signal_pending_data()
def handle_incoming(self, packet):
if self.state == ESTABLISHED and self.control_block.accept_ack(packet):
self.retransmission_queue.acknowledge(packet)
self.clear_retransmission_attempts(packet.get_ack_number())
if (debug):
print("Recibí el ack número: "),
print(str(packet.get_ack_number()))
if self.outgoing_buffer.empty(
) and self.retransmission_queue.empty():
print("Recibi el ultimo ack")
print time.time() - t1
global f, frets, count_rets
f.write(str(time.time() - t1))
f.write("\n")
f.close()
frets.write(str(count_rets))
frets.write("\n")
frets.close()
elif self.state == SYN_SENT and self.control_block.accept_control_ack(
packet):
self.state = ESTABLISHED
self.connected_event.set()
elif self.state == FIN_SENT and self.control_block.accept_control_ack(
packet):
self.state = CLOSED
# Tener en cuenta que se debe:
# * Corroborar que el flag de ACK esté seteado
# Se encarga el control_block
# * Distinguir el caso donde el estado es SYN_SENT
# Dale
# * No olvidar de hacer self.connected_event.set() al confirmar el ACK y establecer la conexión!!!
# A full
# * Analizar si #ACK es aceptado (hablar con el bloque de control para hacer este checkeo)
# Sí
# * Sacar de la cola de retransmisión los paquetes reconocidos por #ACK
# Lo hace la cola
# * Ajustar la ventana deslizante con #ACK
# Lo hace el control_block
# * Tener en cuenta también el caso donde el estado es FIN_SENT
# Ok
def clear_retransmission_attempts(self, ack):
for seq_number in self.retransmission_attempts.keys():
if seq_number <= ack:
del self.retransmission_attempts[seq_number]
def handle_close_connection(self):
if not self.outgoing_buffer.empty():
self.worker.signal_pending_data()
self.worker.signal_close_connection()
elif not self.retransmission_queue.empty():
self.worker.signal_close_connection()
else:
fin_packet = self.build_packet(flags=[FINFlag])
self.send_and_queue_packet(fin_packet)
self.state = FIN_SENT
def close(self):
if self.is_connected():
self.worker.signal_close_connection()
def shutdown(self):
self.outgoing_buffer.clear()
self.retransmission_queue.clear()
self.retransmission_attempts.clear()
self.worker.stop()
# Esto es por si falló el establecimiento de conexión (para destrabar al thread principal)
self.connected_event.set()
self.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 PTCClientProtocol(object):
def __init__(self, address, port):
self.retransmission_queue = RetransmissionQueue(self)
self.retransmission_attempts = dict()
self.outgoing_buffer = DataBuffer()
self.state = CLOSED
self.control_block = ClientControlBlock(address, port)
self.socket = Soquete(address, port)
self.packet_builder = PacketBuilder(self)
def is_connected(self):
return self.state == ESTABLISHED
def build_packet(self, payload=None, flags=None):
seq = self.control_block.get_send_seq()
#if payload is not None:
self.control_block.increment_send_seq()
packet = self.packet_builder.build(payload=payload, flags=flags, seq=seq)
return packet
def send_packet(self, packet):
if(debug):
print("Voy a mandar el paquete número: "),
print(str(packet.get_seq_number()))
#if random.randint(1, 11) == 1:
# simulo congestión
# return
self.socket.send(packet)
def send_and_queue_packet(self, packet):
self.send_packet(packet)
self.retransmission_queue.put(packet)
def send(self, data):
if not self.is_connected():
raise Exception('cannot send data: connection not established')
self.worker.send(data)
global t1
t1 = time.time()
def connect_to(self, address, port):
self.worker = ClientProtocolWorker.spawn_for(self)
self.worker.start()
self.connected_event = threading.Event()
self.control_block.set_destination_address(address)
self.control_block.set_destination_port(port)
syn_packet = self.build_packet(flags=[SYNFlag])
self.send_and_queue_packet(syn_packet)
self.state = SYN_SENT
self.connected_event.wait()
def handle_timeout(self):
global count_rets
count_rets += 1
if(debug or True):
print ("Parece que se perdió un paquete, voy a reenviar.")
new_queue = RetransmissionQueue(self)
for packet in self.retransmission_queue:
if packet not in self.retransmission_attempts:
self.retransmission_attempts[packet.get_seq_number()] = 0
self.retransmission_attempts[packet.get_seq_number()] += 1
if self.retransmission_attempts[packet.get_seq_number()] >= MAX_RETRANSMISSION_ATTEMPTS:
self.shutdown()
self.error = "Intentos de retransmisión superó el máximo"
break
else:
self.send_packet(packet)
new_queue.put(packet)
self.retransmission_queue = new_queue
def handle_pending_data(self):
more_data_pending = False
if self.control_block.send_allowed():
try:
data = self.outgoing_buffer.get(MIN_PACKET_SIZE, MAX_PACKET_SIZE)
except NotEnoughDataException:
pass
else:
packet = self.build_packet(payload=data)
self.send_and_queue_packet(packet)
if not self.outgoing_buffer.empty():
more_data_pending = True
else:
more_data_pending = True
if more_data_pending:
self.worker.signal_pending_data()
def handle_incoming(self, packet):
if self.state == ESTABLISHED and self.control_block.accept_ack(packet):
self.retransmission_queue.acknowledge(packet)
self.clear_retransmission_attempts(packet.get_ack_number())
if(debug):
print("Recibí el ack número: "),
print(str(packet.get_ack_number()))
if self.outgoing_buffer.empty() and self.retransmission_queue.empty():
print("Recibi el ultimo ack")
print time.time() - t1
global f, frets, count_rets
f.write(str(time.time() - t1))
f.write("\n")
f.close()
frets.write(str(count_rets))
frets.write("\n")
frets.close()
elif self.state == SYN_SENT and self.control_block.accept_control_ack(packet):
self.state = ESTABLISHED
self.connected_event.set()
elif self.state == FIN_SENT and self.control_block.accept_control_ack(packet):
self.state = CLOSED
# Tener en cuenta que se debe:
# * Corroborar que el flag de ACK esté seteado
# Se encarga el control_block
# * Distinguir el caso donde el estado es SYN_SENT
# Dale
# * No olvidar de hacer self.connected_event.set() al confirmar el ACK y establecer la conexión!!!
# A full
# * Analizar si #ACK es aceptado (hablar con el bloque de control para hacer este checkeo)
# Sí
# * Sacar de la cola de retransmisión los paquetes reconocidos por #ACK
# Lo hace la cola
# * Ajustar la ventana deslizante con #ACK
# Lo hace el control_block
# * Tener en cuenta también el caso donde el estado es FIN_SENT
# Ok
def clear_retransmission_attempts(self, ack):
for seq_number in self.retransmission_attempts.keys():
if seq_number <= ack:
del self.retransmission_attempts[seq_number]
def handle_close_connection(self):
if not self.outgoing_buffer.empty():
self.worker.signal_pending_data()
self.worker.signal_close_connection()
elif not self.retransmission_queue.empty():
self.worker.signal_close_connection()
else:
fin_packet = self.build_packet(flags=[FINFlag])
self.send_and_queue_packet(fin_packet)
self.state = FIN_SENT
def close(self):
if self.is_connected():
self.worker.signal_close_connection()
def shutdown(self):
self.outgoing_buffer.clear()
self.retransmission_queue.clear()
self.retransmission_attempts.clear()
self.worker.stop()
# Esto es por si falló el establecimiento de conexión (para destrabar al thread principal)
self.connected_event.set()
self.state = CLOSED
def __init__(self, address, port):
self.state = CLOSED
self.control_block = ServerControlBlock(address, port)
self.socket = Soquete(address, port)
self.packet_builder = PacketBuilder(self)
self.connection_closed_event = threading.Event()
class PTCServerProtocol(object):
def __init__(self, address, port):
self.state = CLOSED
self.control_block = ServerControlBlock(address, port)
self.socket = Soquete(address, port)
self.packet_builder = PacketBuilder(self)
self.connection_closed_event = threading.Event()
def is_connected(self):
return self.state == ESTABLISHED
def is_closed(self):
return self.state == CLOSED
def build_packet(self, flags=None):
ack = self.control_block.get_receive_seq()
packet = self.packet_builder.build(flags=flags, ack=ack)
return packet
def send_packet(self, packet):
self.socket.send(packet)
def receive(self, size):
if self.is_closed() and self.incoming_buffer.empty():
raise Exception('cannot receive: connection ended and no more pending data buffered')
elif self.incoming_buffer.empty() and not self.is_connected():
raise Exception('cannot receive: connection not established')
if size < MIN_PACKET_SIZE:
size = MIN_PACKET_SIZE
data = self.incoming_buffer.sync_get(MIN_PACKET_SIZE, size)
return data
def accept(self):
self.incoming_buffer = DataBuffer()
self.state = CLOSED
self.worker = ServerProtocolWorker.spawn_for(self)
self.worker.start()
# No hay mucho por hacer... simplemente esperar a que caiga el SYN del cliente
self.connected_event = threading.Event()
self.connected_event.wait()
def handle_incoming(self, packet):
seq_number = packet.get_seq_number()
if(debug):
print ("Recibi el paquete numero: "),
print (seq_number)
if SYNFlag in packet:
self.control_block.set_destination_address(packet.get_source_ip())
self.control_block.set_destination_port(packet.get_source_port())
self.control_block.set_receive_seq(seq_number)
ack_packet = self.build_packet(flags=[ACKFlag])
self.send_packet(ack_packet)
self.control_block.set_receive_seq(seq_number)
self.control_block.increment_receive_seq()
self.state = ESTABLISHED
self.connected_event.set()
if FINFlag in packet:
if self.control_block.accepts(seq_number):
self.state = FIN_RECEIVED
self.send_ack()
self.close()
else:
data = packet.get_payload()
if self.control_block.accepts(seq_number) and data:
self.incoming_buffer.put(data)
if self.state != FIN_RECEIVED:
self.send_ack()
self.control_block.increment_receive_seq()
def send_ack(self):
ack_packet = self.build_packet(flags=[ACKFlag])
self.send_packet(ack_packet)
def shutdown(self):
self.worker.stop()
# Esto es por si falló el establecimiento de conexión (para destrabar al thread principal)
self.connected_event.set()
def close(self):
self.state = CLOSED
self.connection_closed_event.set()
def wait_for_close(self):
self.connection_closed_event.wait()
