def rdt_rcv(sock):
data = extract(sock)
if data == 0:
return None
# parse packets
ACK = data[0:4]
rec_seq = data[4:20]
rec_cksum = rdt_utils.parse_checksum(data[20:])
# Handle error possibilities
if rdt_utils.has_ack_bit_err(
) and rdt_utils.random_channel() < config.percent_corrupt:
corruptData = rdt_utils.corrupt_bits(ACK)
calc = corruptData + rec_seq
elif rdt_utils.has_ack_packet_loss(
) and rdt_utils.random_channel() < config.percent_corrupt:
rdt_utils.debug_print(f"ACK Packet #{int(rec_seq, 2)} Dropped !")
return None
else:
calc = ACK + rec_seq
checksum = rdt_utils.calc_checksum(calc)
if rec_cksum != checksum:
rdt_utils.debug_print(
f"Bit error encountered in ACK #{int(rec_seq, 2)}!")
return None
rdt_utils.debug_print(
f'ACK Packet #{int(rec_seq, 2)} successfully received')
return int(rec_seq, 2)
def rdt_rcv(sock, seqNum):
data = extract(sock)
if data == 0:
return 0
# parse packets
ACK = data[0:4]
recSeq = data[4:5]
rec_cksum = rdt_utils.parse_checksum(data[5:])
if rdt_utils.has_ack_bit_err(
) and rdt_utils.random_channel() < config.percent_corrupt:
if config.debug:
print("Bit error encountered in ACK!")
corruptData = rdt_utils.corrupt_bits(ACK)
calc = corruptData + recSeq
elif rdt_utils.has_ack_packet_loss(
) and rdt_utils.random_channel() < config.percent_corrupt:
if config.debug:
print("ACK Packet Dropped!")
return 0
else:
calc = ACK + recSeq
checksum = rdt_utils.calc_checksum(calc)
return ACK == b'1111' and recSeq == seqNum and rec_cksum == checksum
def rdt_rcv(fname, sock):
expected_seq_num = 0
expected_seq_num_b = rdt_utils.seq_num_to_bin(expected_seq_num)
ACK = bin(15)[2:].encode('utf-8')
oncethru = False
endpoint = None # Endpoint starts off unitialized, get it from first received packet
f = None # Don't open file until know that we received message
sndpkt = None
while True:
pkt, addr = extract(sock)
# Initialize endpoint with actual addr received
if not endpoint and addr:
endpoint = addr
# Got actual message
if pkt and addr:
# Open file if not opened
if not f:
f = open(fname, 'wb')
#parse packet
rec_seq = pkt[0:16]
rec_ck = rdt_utils.parse_checksum(pkt[16:18])
data = pkt[18:]
if rdt_utils.has_data_bit_err(
) and rdt_utils.random_channel() < config.percent_corrupt:
if config.debug:
print("Bit error encountered in Data!")
corruptData = rdt_utils.corrupt_bits(data)
calc = rec_seq + corruptData
else:
calc = rec_seq + data
chksum = rdt_utils.calc_checksum(calc)
# correct sequence number
if (not config.loss_recovery
or expected_seq_num_b == rec_seq) and chksum == rec_ck:
deliver_data(f, data)
sndpkt = make_pkt(ACK, rec_seq)
udt_send(sndpkt, endpoint, sock)
expected_seq_num += 1
expected_seq_num_b = rdt_utils.seq_num_to_bin(expected_seq_num)
else:
# didn't receive right pkt, either seqnum wrong or cksum
if config.debug:
print("Bad data received, sending prev ACK")
if oncethru and sndpkt:
udt_send(sndpkt, endpoint, sock)
else:
# Close file if opened
if f:
f.close()
break
oncethru = True
return endpoint
def rdt_rcv(file, endpoint, sock):
oncethru = 0
seqNum = 0
seq = bin(seqNum)[2:].encode("utf-8")
ACK = bin(15)[2:].encode('utf-8')
while True:
pkt = extract(sock)
if pkt:
#parse packet
recSeq = pkt[0:1]
rec_ck = rdt_utils.parse_checksum(pkt[1:3])
data = pkt[3:]
if rdt_utils.has_data_bit_err(
) and rdt_utils.random_channel() < config.percent_corrupt:
if config.debug:
print("Bit error encountered in Data!")
corruptData = rdt_utils.corrupt_bits(data)
calc = recSeq + corruptData
else:
calc = recSeq + data
chksum = rdt_utils.calc_checksum(calc)
# correct sequence number
if seq == recSeq and chksum == rec_ck:
deliver_data(file, data)
sndpkt = make_pkt(ACK, recSeq, chksum)
udt_send(sndpkt, endpoint, sock)
# switch sequence number
if seqNum == 0:
seqNum = 1
else:
seqNum = 0
seq = bin(seqNum)[2:].encode("utf-8")
oncethru = 1
else:
# didn't receive right pkt, either seqnum wrong or cksum
if oncethru == 1:
if config.debug:
print("Bad data received, sending prev ACK")
udt_send(sndpkt, endpoint, sock)
else:
if config.debug:
print("Bad data received in first packet")
else:
file.close()
break
def rdt_send(file, endpoint, sock):
timer = rdt_utils.RDTTimer(config.timeout)
# Returns callback function for when timeout reached
def timeout_func(packet, endpoint, sock):
def ret_func():
if config.debug:
print("Timeout for ACK exceeded, resending packet")
udt_send(packet, endpoint, sock)
# Forget last timer and start new one
timer.start(timeout_func(packet, endpoint, sock))
return ret_func
seqNum = 0
seq = bin(seqNum)[2:].encode("utf-8")
packet = make_pkt(file, seq)
while packet != 0:
if rdt_utils.has_data_packet_loss(
) and rdt_utils.random_channel() < config.percent_corrupt:
if config.debug:
print("DATA Packet Dropped!")
else:
udt_send(packet, endpoint, sock)
timer.start(timeout_func(packet, endpoint, sock))
while not rdt_rcv(sock, seq):
pass
timer.cancel()
if seqNum == 0: # switch sequence numbers
seqNum = 1
else:
seqNum = 0
seq = bin(seqNum)[2:].encode("utf-8")
packet = make_pkt(file, seq)
time.sleep(0.005)
def udt_send(packet, endpoint, sock, packet_num):
if rdt_utils.has_data_packet_loss(
) and rdt_utils.random_channel() < config.percent_corrupt:
rdt_utils.debug_print(f'DATA Packet #{packet_num} Dropped!')
return
return sock.sendto(packet, endpoint)
def udt_send(packet, endpoint, sock):
if rdt_utils.has_data_packet_loss() and rdt_utils.random_channel() < config.percent_corrupt:
if config.debug:
print("DATA Packet Dropped!")
return
return sock.sendto(packet, endpoint)
def rdt_rcv(fname, sock):
rcv_buf = rdt_utils.RCVPacketBuffer(config.max_buf_size,
config.window_size)
ACK = bin(15)[2:].encode('utf-8')
endpoint = None # Endpoint starts off unitialized, get it from first received packet
f = None # Don't open file until know that we received message
sndpkt = None
while True:
pkt, addr = extract(sock)
# Initialize endpoint with actual addr received
if not endpoint and addr:
endpoint = addr
# Got actual message
if pkt and addr:
# Open file if not opened
if not f:
f = open(fname, 'wb')
#parse packet
rec_seq = pkt[0:16]
rec_ck = rdt_utils.parse_checksum(pkt[16:18])
data = pkt[18:]
if rdt_utils.has_data_bit_err(
) and rdt_utils.random_channel() < config.percent_corrupt:
corruptData = rdt_utils.corrupt_bits(data)
calc = rec_seq + corruptData
else:
calc = rec_seq + data
chksum = rdt_utils.calc_checksum(calc)
rec_seq_int = int(rec_seq, 2)
if chksum == rec_ck:
sndpkt = make_pkt(ACK, rec_seq)
if rcv_buf.includes(rec_seq_int):
udt_send(sndpkt, endpoint, sock)
rcv_buf.buf[rec_seq_int] = data
rdt_utils.debug_print(
f'Data packet #{int(rec_seq, 2)} added to receive buffer'
)
# Inorder
if rec_seq_int == rcv_buf.base:
while rcv_buf.buf[rcv_buf.base] is not None:
deliver_data(f, rcv_buf.buf[rcv_buf.base])
rdt_utils.debug_print(
f'Data {rcv_buf.base} delivered to file')
rcv_buf.base += 1
elif rec_seq_int < rcv_buf.base:
udt_send(sndpkt, endpoint, sock)
else:
# didn't receive right pkt, wrong cksum
rdt_utils.debug_print(
f'Bit error encountered in data packet #{int(rec_seq, 2)}, doing nothing'
)
else:
# Close file if opened
if f:
f.close()
break
return endpoint