def main():
server_sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
server_sock.bind((UDP_IP_ADDRESS, UDP_PORT_NO))
print('Receiver started on ', UDP_IP_ADDRESS, ':', UDP_PORT_NO, sep="")
print('Your file(s) will be saved in', (receiver_folder + '/'), end="\n\n")
while (True):
data, addr = server_sock.recvfrom(Packet.MAX_PACKET_SIZE)
sender_port = addr[1]
recv_pkt = None
try:
recv_pkt = Packet.bytesToPacket(data)
except:
continue
if (recv_pkt.CHECKSUM != recv_pkt.compute_checksum()): # invalid data
continue
# Message type
msg_type = recv_pkt.TYPE
# Message id
msg_id = recv_pkt.ID
# Message sequence
msg_seq = recv_pkt.SEQ
# Send ACK-like packet
ack_packet = None
if (msg_type == Packet.DATA):
ack_packet = Packet(Packet.ACK, msg_id, msg_seq)
elif (msg_type == Packet.FIN):
ack_packet = Packet(Packet.FIN_ACK, msg_id, msg_seq)
server_sock.sendto(ack_packet.get_Packet(), addr)
msg_data = recv_pkt.DATA
client = {}
if (not Client.is_connected_client(sender_port)): # new client
client = Client(sender_port)
else:
client = Client.get_client(sender_port)
file_idx = client.search_file(msg_id)
if (file_idx == -1):
print("Receiving new file with\nPacket ID:",
msg_id,
"\nPort:",
client.port,
end="\n\n")
file_idx = client.add_new_file(msg_id)
file_obj = client.files[file_idx]
if (msg_type == Packet.DATA):
if ((file_obj.sequence + 1) == msg_seq and file_obj.is_active()):
file_obj.sequence += 1
file_obj.write(msg_data)
elif (msg_type == Packet.FIN):
if ((file_obj.sequence + 1) == msg_seq and file_obj.is_active()):
file_obj.update_sequence()
file_obj.write(msg_data)
file_obj.finalize()
print("File with\nPacket ID:",
msg_id,
"\nPort:",
client.port,
"\nSuccessfully received!",
end="\n\n")
