def __init__(self):
# run the super initializer
Net.__init__(self)
# add the specific arguments for a client server
self.parser.add_argument('-f',
metavar='filename',
type=str,
help='The filename of a file to write/read')
self.parser.add_argument('-a',
metavar='address',
type=str,
help='The ip address of the server')
self.parser.add_argument('-w',
action='store_true',
help='Flag for writing a file')
self.parser.add_argument('-r',
action='store_true',
help='Flag for reading a file')
self.parser.add_argument('-k',
action='store_true',
help='Flag for killing the server')
# parse the arguments
args = self.parser.parse_args()
server_connection = (args.a, args.p)
# if you want to kill, open connection, and send kill
if args.k:
self.sock.sendto(Packet.kill(), server_connection)
exit(0)
if not path.exists(args.f):
print("File not found, please enter a valid filename")
exit(0)
# Creating connection to server
# source port is 0 since the connection has been made yet
print("Initiating connection")
self.sock.sendto(
Packet.request(args.f, args.w, args.p, 0,
self.seq_number).binary_combine(),
server_connection)
self.sock.settimeout(2)
try:
syn_ack, address = self.sock.recvfrom(1472)
read_syn = Packet.read_packet(syn_ack)
if read_syn[1]:
if read_syn[0] == "Ack Syn":
print(
"Proper ack received, send ack back, then data/waiting for data"
)
self.port = read_syn[3]
window_size = read_syn[5]
ack = read_syn[2] + len(syn_ack)
self.sock.sendto(
Packet.ack(self.seq_number,
ack,
args.p,
self.port,
window_size,
syn=True).binary_combine(),
server_connection)
if args.w:
self.send_data(args.f, window_size, args.a, args.p,
self.sock)
else:
self.receive_data(args.f, self.sock, args.p,
window_size, ack, args.a)
else:
print("Improper ack received, please try connection again")
self.sock.close()
exit(0)
else:
print(
"Error in the checksum for ack syn, please try connection again"
)
self.sock.close()
exit(0)
except socket.timeout:
print("Connection time out, connection not established")
exit(0)
def receive_data(self, filename, sock, d_port, win_size, start_ack,
d_address):
write_file = open('new' + filename, 'wb')
last_packet = False
MAX_RETRIES = 5
ack = start_ack
while not last_packet:
error_flag = False
retries = 0
packets = []
# Receiving the full window
for i in range(win_size):
sock.settimeout(2)
try:
print("Getting packet " + str(len(packets)) +
" from the sender")
receive_packet, address = sock.recvfrom(1472)
packets.append(receive_packet)
except socket.timeout as e:
if len(packets) == 0:
if retries < MAX_RETRIES:
print("Receive timeout, retry: " + str(retries))
retries += 1
else:
print("Max retries reached, closing connection")
sock.close()
if packets:
for packet in packets:
data = Packet.read_packet(packet)
if data[1]:
if data[0] == "Data":
if data[2] == ack:
print(
"Proper data packet received, writing data..."
+ str(data[2]))
write_data = data[3].tobytes()
write_file.write(write_data)
ack = Net.up_ack(ack, len(BitArray(packet)))
print("New ack :" + str(ack))
else:
print(
"Improper sequence number received, dumping improper packets"
+ str(data[2]))
packets.clear()
elif data[0] == "Fin":
if data[2] == ack:
print(
"Final packet received, writing, acking, then closing connection"
)
write_file.write(data[3].tobytes())
ack = Net.up_ack(ack, len(BitArray(packet)))
last_packet = True
else:
print(
"Error detected, creating error packet, dumping packets"
)
send_packet = Packet.error(0,
d_port,
self.port,
self.seq_number,
ack_num=ack,
in_message="Checksum error")
error_flag = True
packets.clear()
self.up_sequence_number(
len(send_packet.binary_combine()))
if not error_flag:
send_packet = Packet.ack(self.seq_number, ack, d_port,
self.port, win_size)
print("Sending ack packet " + str(ack))
sock.sendto(send_packet.binary_combine(), (d_address, d_port))
else:
print("No packets received, closing connection")
sock.close()
def __init__(self):
# Run super initializer
Net.__init__(self)
# parse the arguments
args = self.parser.parse_args()
self.port = args.p
self.win_size = random.randint(4, 9)
while True:
self.re_sock()
self.sock.bind(('', args.p))
print("Server IP: " + str(self.sock.getsockname()) + "\nPort number: " + str(
args.p) + "\nWaiting for connection")
self.sock.settimeout(None)
message, address = self.sock.recvfrom(1472)
decoded_message = Packet.read_packet(message)
# Kill packet received
if decoded_message[0] == 'end':
self.sock.close()
exit(0)
if decoded_message[1]:
if decoded_message[0] == "Syn":
print("Connection requested from " + str(address))
print("Sending syn ack...")
ack = decoded_message[2]
write_flag = decoded_message[3]
filename = decoded_message[4]
self.sock.sendto(Packet.ack(self.seq_number, ack, address[1], self.port, self.win_size,
syn=True).binary_combine(), address)
self.sock.settimeout(2)
try:
message, address = self.sock.recvfrom(1472)
decoded_message = Packet.read_packet(message)
if decoded_message[1]:
if decoded_message[0] == "Ack Syn":
print("Three way handshake confirmed")
if write_flag:
# Since a file added to the server will be preappended with 'new', this needs to be checked as well
if path.exists(filename) or path.exists('new'+filename):
print("Trying to send a file that already exists, sending error, closing "
"connection")
return_packet = Packet.error(6, address[1], self.port, self.seq_number)
self.sock.sendto(return_packet.binary_combine(), address)
else:
print("Ready to receive data...")
Net.receive_data(self, "new" + filename, self.sock, address[1], self.win_size,
ack, address[0])
else:
if path.exists('new' + filename):
pathname = 'new' + filename
else:
pathname = filename
# Sending a file not found error, this is redundant check if there is a 'new' + filename but if there
# isn't one this one checks for the original name
if not path.exists(pathname):
print("trying to send a file that doesn't exist, sending error, closing "
"connection")
send_packet = Packet.error(1, address[1], self.port, self.seq_number)
self.sock.sendto(send_packet.binary_combine(), address)
else:
print("Sending data...")
Net.send_data(self, pathname, self.win_size, address[0], address[1], self.sock)
except socket.timeout as e:
print("Syn ack timeout, connection refused")