def rec(self, recv_window):
#if self.connection_status != Status.IDLE:
# raise CRPException("Status is not idle!")
resends_rem = self.resend_limit
while resends_rem > 0:
try:
self.socket.settimeout(5)
recv_data, recv_addr = self.recv_packet(self.recv_window)
except socket.timeout:
resends_rem -= 1
continue
else:
recv_pckt = CRPPacket(packet=recv_data)
if recv_pckt.calc_checksum() == recv_pckt.checksum and recv_pckt.data != str(None) \
and self.connection_status == Status.CONNECTED:
print (recv_pckt.data)
self.send_ACK()
elif recv_pckt.calc_checksum() != recv_pckt.checksum:
raise CRPException(CRPException.CHECKSUM_INVALID)
if recv_pckt.FIN and not recv_pckt.ACK:
self.send_FINACK()
print("Disconnected from Client.")
self.connection_status = Status.LISTEN
return (recv_data, recv_addr)
else:
return (recv_data, recv_addr)
if resend_rem == 0:
raise CRPException(CRPException.TIMEOUT)
def send_FINACK(self):
fin_ack_pckt = CRPPacket(src_port=self.src_addr[1], dest_pstevejobsort=self.dest_addr[1], \
seq_num=self.sequence_num, ack_num=self.ack_num)
fin_ack_pckt.FIN = 1
fin_ack_pckt.ACK = 1
self.sequence_num += 1
resends_rem = self.resend_limit
recv_pckt = None
while resends_rem > 0:
self.send_packet(fin_ack_pckt.get_packet())
try:
recv_data, recv_addr = self.rec(self.recv_window)
recv_pckt = CRPPacket(packet=recv_data)
except CRPException as exception:
if (exception.type == CRPException.CHECKSUM_INVALID):
continue
else:
if recv_pckt != None and recv_pckt.ACK:
break
elif recv_pckt != None and recv_pckt.FIN:
resends_rem = self.resend_limit
if resends_rem == 0:
raise CRPException(CRPException.TIMEOUT)
def send_SYN(self):
syn_pckt = CRPPacket(src_port=self.src_addr[1], dest_port=self.dest_addr[1], seq_num=self.sequence_num)
syn_pckt.SYN = 1
self.sequence_num += 1
resends_rem = self.resend_limit
recv_pckt = None
while resends_rem > 0:
self.send_packet(syn_pckt.get_packet())
try:
recv_data, recv_addr = self.rec(self.recv_window)
recv_pckt = CRPPacket(packet=recv_data)
except CRPException as exception:
if (exception.type == CRPException.CHECKSUM_INVALID):
continue
else:
if recv_pckt != None and recv_pckt.SYN and recv_pckt.ACK:
break
if resends_rem == 0:
raise CRPException(CRPException.TIMEOUT)
return recv_pckt
def listen(self):
self.connection_status = Status.LISTEN
recv_pckt = None
while True:
try:
recv_data, recv_addr = self.rec(self.recv_window)
recv_pckt = CRPPacket(packet=recv_data)
except CRPException as exception:
if (exception.type == CRPException.CHECKSUM_INVALID):
continue
else:
if recv_pckt != None and recv_pckt.SYN:
break
self.ack_num = int(recv_pckt.seq_num) + 1
self.dest_addr = recv_addr
def send_ACK(self):
ack_pckt = CRPPacket(src_port=self.src_addr[1], dest_port=self.dest_addr[1], ack_num=self.ack_num)
ack_pckt.ACK = 1
self.send_packet(ack_pckt.get_packet())