def check_packet(self, packet):
seqno = packet.seqno
rec_cksum = packet.cksum
calc_cksum = checksum.gen_cksum(
checksum.string_to_byte_arr(packet.data))
if rec_cksum != calc_cksum and seqno != 0:
print(
"\tBy comparing the checksum received and that calculated: packet corrupted. Discard."
)
else:
# Received expected inorder seqno
if seqno == self.expected_seqno:
print("Sending ACK for packet ", seqno)
ack_packet = ack.Ack(0, seqno)
self.socket.sendto(pick.dumps(ack_packet), self.dest)
self.last_ackno = seqno
self.expected_seqno = self.expected_seqno + 1
for i in range(len(packet.data)):
self.file.write(packet.data[i])
print("\tFlushing: packet ", packet.seqno)
self.file.flush()
# Not expected seno
else:
print("Sending DUPLICATE ACK for packet ", self.last_ackno)
ack_packet = ack.Ack(0, self.last_ackno)
self.socket.sendto(pick.dumps(ack_packet), self.dest)
def check_packet(self, packet):
index = packet.seqno - self.base_seqno
rec_cksum = packet.cksum
calc_cksum = checksum.gen_cksum(
checksum.string_to_byte_arr(packet.data))
if rec_cksum != calc_cksum and packet.seqno != 0:
print(
"\tBy comparing the checksum received and that calculated: packet corrupted. Discard."
)
else:
if index < 0: #Already written packet
ack_packet = ack.Ack(0, packet.seqno)
self.socket.sendto(pick.dumps(ack_packet), self.dest)
if index >= 0 and index < self.list_size: #packet in range
if not self.buffer[index]: #packet received for the first time
self.buffer[index] = packet
ack_packet = ack.Ack(0, packet.seqno)
self.socket.sendto(pick.dumps(ack_packet), self.dest)
else: #packet was received before
ack_packet = ack.Ack(0, packet.seqno)
self.socket.sendto(pick.dumps(ack_packet), self.dest)
self.check_buffer()
def recv_one_packet(self):
byte, addr = self.socket.recvfrom(self.BUF_SIZE)
packet = pick.loads(byte)
print("Received packet ", packet.seqno)
rec_cksum = packet.cksum
calc_cksum = checksum.gen_cksum(checksum.string_to_byte_arr(packet.data))
if rec_cksum != calc_cksum and packet.seqno != 0:
print("\tBy comparing the checksum received and that calculated: packet corrupted. Discard.")
return 1
else:
if packet.seqno == 0:
print("Close packet received, file received successfully")
return 0
else:
for i in range(len(packet.data)):
self.file.write(packet.data[i])
self.file.flush()
ack_packet = ack.Ack(0, packet.seqno)
self.socket.sendto(pick.dumps(ack_packet), self.dest)
return 1