def receive_packet(self, packet):
# handle ACK
if self.packet_is_outstanding and packet.ack_number == self.sequence:
# this acks new data, so advance the send buffer, reset
# the outstanding flag, cancel the timer, and send if possible
Sim.trace(
"%d received StopAndWait ACK from %d for %d"
% (packet.destination_address, packet.source_address, packet.ack_number)
)
self.send_buffer = self.send_buffer[self.sequence - self.last_sent :]
self.packet_is_outstanding = False
self.cancel_timer()
self.send_if_possible()
# handle data
if packet.length > 0:
Sim.trace(
"%d received StopAndWait segment from %d for %d"
% (packet.destination_address, packet.source_address, packet.sequence)
)
# if the packet is the one we're expecting increment our
# ack number and add the data to the receive buffer
if packet.sequence == self.ack:
self.increment_ack(packet.sequence + packet.length)
self.receive_buffer += packet.body
# deliver data that is in order
self.app.receive_packet(packet)
# always send an ACK
self.send_ack()
def forward_packet(self,packet):
if packet.destination_address not in self.forwarding_table:
Sim.trace("%d no routing entry for %d" % (self.links[0].address,packet.destination_address))
return
link = self.forwarding_table[packet.destination_address]
Sim.trace("%d forwarding packet to %d" % (link.address,packet.destination_address))
link.handle_packet(packet)
def trace(self,message):
''' Print debugging messages. '''
if self.destination_port != self.plot_port_number:
return
if not self.plot_sequence_on and not self.plot_rate_on and not self.plot_queue_on and not self.plot_window_on:
Sim.trace("TCP",message)
def retransmit(self,event):
if not self.send_buffer:
return
if not self.packet_is_outstanding:
return
Sim.trace("%d retransmission timer fired" % (self.source_address))
packet = self.send_one_packet(self.last_sent)
def forward_unicast_packet(self,packet):
if packet.destination_address not in self.forwarding_table:
Sim.trace("%s no routing entry for %d" % (self.hostname,packet.destination_address))
return
link = self.forwarding_table[packet.destination_address]
Sim.trace("%s forwarding packet to %d" % (self.hostname,packet.destination_address))
link.send_packet(packet)
def plot_sequence(self, sequence_number, isACK = False, dropped=False):
if self.destination_port != self.plot_port_number:
return
message = "%i %i %d" % (sequence_number, dropped, isACK)
if self.plot_sequence_on:
Sim.trace("TCP", message)
def plot_window(self, size):
if self.destination_port != self.plot_port_number:
return
message = "%i" % size
if self.plot_window_on:
Sim.trace("TCP", message)
def send_ack(self):
packet = TCPPacket(source_address=self.source_address,
source_port=self.source_port,
destination_address=self.destination_address,
destination_port=self.destination_port,
sequence=self.sequence,ack_number=self.ack)
# send the packet
Sim.trace("%d sending StopAndWait ACK to %d for %d" % (self.source_address,self.destination_address,packet.ack_number))
self.transport.send_packet(packet)
def handle_packet(self,packet):
# if this is the first time we have seen this packet, set its
# creation timestamp
if packet.created == None:
packet.created = Sim.scheduler.current_time()
# check if the packet is for me
for link in self.links:
if link.address == packet.destination_address:
Sim.trace("%d received packet" % (packet.destination_address))
self.receive_packet(packet)
return
# forward the packet
self.forward_packet(packet)
def send_one_packet(self,sequence):
# get one packet worth of data
body = self.send_buffer[0:self.mss]
packet = TCPPacket(source_address=self.source_address,
source_port=self.source_port,
destination_address=self.destination_address,
destination_port=self.destination_port,
body=body,
sequence=sequence,ack_number=self.ack)
# send the packet
Sim.trace("%d sending StopAndWait segment to %d for %d" % (self.source_address,self.destination_address,packet.sequence))
self.transport.send_packet(packet)
# set a timer
self.timer = Sim.scheduler.add(delay=self.timeout, event='retransmit', handler=self.retransmit)
return packet
def handle_packet(self,packet):
# drop packet due to queue overflow
if self.queue_size and len(self.queue) == self.queue_size:
Sim.trace("! %d dropped packet due to queue overflow" % (self.address))
Sim.trace_custom('x', 'queue', self.filename)
return
# drop packet due to random loss
if self.loss > 0 and random.random() < self.loss:
Sim.trace("! %d dropped packet due to random loss" % (self.address))
return
packet.enter_queue = Sim.scheduler.current_time()
#Sim.trace("packet %d entered queue" % packet.sequence)
if len(self.queue) == 0 and not self.busy:
# packet can be sent immediately
self.busy = True
self.transmit(packet)
else:
# add packet to queue
Sim.trace_custom('%d' % (len(self.queue)), 'queue', self.filename)
self.queue.append(packet)
def send_packet(self,packet):
# check if link is running
if not self.running:
return
# drop packet due to queue overflow
if self.queue_size and len(self.queue) == self.queue_size:
Sim.trace("%d dropped packet due to queue overflow" % (self.address))
return
# drop packet due to random loss
if self.loss > 0 and random.random() < self.loss:
Sim.trace("%d dropped packet due to random loss" % (self.address))
return
packet.enter_queue = Sim.scheduler.current_time()
if len(self.queue) == 0 and not self.busy:
# packet can be sent immediately
self.busy = True
self.transmit(packet)
else:
# add packet to queue
self.queue.append(packet)
def handle_packet(self,packet):
# drop packet due to queue overflow
if self.queue_size and len(self.queue) == self.queue_size:
Sim.trace("%d dropped packet due to queue overflow" % (self.address))
if self.printOut:
self.myfile.write(str(Sim.scheduler.current_time()) + " x\n")
Sim.print_packet_loss(packet)
return
# drop packet due to random loss
if self.loss > 0 and random.random() < self.loss:
Sim.trace("%d dropped packet due to random loss" % (self.address))
if self.printOut:
self.myfile.write(str(Sim.scheduler.current_time()) + " x\n")
return
packet.enter_queue = Sim.scheduler.current_time()
if len(self.queue) == 0 and not self.busy:
# packet can be sent immediately
self.busy = True
self.transmit(packet)
else:
# add packet to queue
self.queue.append(packet)
def receive_packet(self,packet):
# handle broadcast packets
if packet.destination_address == 0:
Sim.trace("%s received packet" % (self.hostname))
self.deliver_packet(packet)
else:
# check if unicast packet is for me
for link in self.links:
if link.address == packet.destination_address:
Sim.trace("%s received packet" % (self.hostname))
self.deliver_packet(packet)
return
# decrement the TTL and drop if it has reached the last hop
packet.ttl = packet.ttl - 1
if packet.ttl <= 0:
Sim.trace("%s dropping packet due to TTL expired" % (self.hostname))
return
# forward the packet
self.forward_packet(packet)
def trace_queue(self, message):
Sim.trace("Queue", message)
def receive_data(self, data):
Sim.trace('AppHandler', "application got %d bytes" % (len(data)))
self.f.write(data)
self.f.flush()
def trace(self, message):
Sim.trace("DVR", message)
def trace(self,message):
Sim.trace("Node",message)
def trace(self,message):
Sim.trace("Link",message)
def trace(self, message):
Sim.trace("Link", message)
def forward_broadcast_packet(self,packet):
for link in self.links:
Sim.trace("%s forwarding broadcast packet to %s" % (self.hostname,link.endpoint.hostname))
packet_copy = copy.deepcopy(packet)
link.send_packet(packet_copy)
def trace(self,message):
''' Print debugging messages. '''
Sim.trace("TCP",message)
def receive_data(self,data):
Sim.trace('AppHandler',"application got %d bytes" % (len(data)))
self.f.write(data)
self.f.flush()
