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w-modem.py
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import socket
import threading
import math
from EventManager import EventManager
import time
class WModem():
"""
A class to connect and interact with a server with the WModem protocall
Args:
host (str): IP to connect to
port (int): port to connect to
key = b''(int): The encryption key to use
startxt = True (bool): Whether to print the WModem version
"""
def __init__(self, host, port, key = b'', startxt = True):
self.version = [0x0,0x01,0x01]
if type(key) != int:
raise ValueError(f"Key must be an int and not a {type(key)}")
self.key = bytes(key)
self.version_txt = "WModem Version: "
if self.version[0] == 0x0:
self.version_txt += "dev"
elif self.version[0] == 0x1:
self.version_txt += "alpha"
elif self.version[0] == 0x2:
self.version_txt += "beta"
elif self.version[0] == 0x3:
self.version_txt += "pre-release"
elif self.version[0] == 0x4:
self.version_txt += "release"
self.version_txt += " "+str(int(self.version[1]))
for num in self.version[2:]:
self.version_txt += "."+str(int(num))
if startxt:
print(self.version_txt)
self.events = EventManager()
self.socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self.packet_mods = {
"Data": 0x80,
"DtD": 0x81,
"SEA": 0x8C,
"SOP": 0x8D,
"HED": 0x8E,
"EOP": 0x8F
}
self.commands = {
"ACK": 0x86,
"NAK": 0x87,
"ABO": 0x88,
"OCK": 0x89,
"ERR": 0x8A,
"IGN": 0x8B,
"KAC": 0x90,
}
self.busy = False
self.buffer = bytearray() # Use bytearray to accumulate incoming data
self.packet_size = 1024
self.packet_number = 0
self.packet_number_ack = 0
self.packet_number_err = 0
self.ign_count = 0
self.connected = False
self.receive_thread = threading.Thread(target=self.receive_loop, daemon=True)
self.receive_thread = threading.Thread(target=self.keep_alive_loop, daemon=True)
self.receive_thread.start() # Start the background thread for receiving data
def keep_alive_loop(self):
while True:
try:
self.send_packet("KAC","DtD")
time.sleep(1)
for packet in self.buffer:
payload = packet[packet.index(self.packet_mods["SOP"])+1:packet.index(self.packet_mods["EOP"])-2]
t = packet[packet.index(self.packet_mods["HED"])+1]
if t == self.packet_mods["DtD"] and payoad == self.commands["KAC"]:
break
else:
raise ValueError("KAC not responded to")
except Exception as e:
print(f"KAC error: {e}")
def connect(self):
i = 0
self.busy = True
while not self.connected and i <=10:
self.socket.send(self.packet_mods["SEA"])
time.sleep(0.1)
if len(self.buffer) == 0:
i += 1
else:
self.connected = True
if not self.connected:
raise ValueError("Could not connect to other computer")
self.busy = False
def packet_template(self,type,payload):
checksum = self.calculate_checksum(payload)
length = len(payload)
if type == "Data":
return bytes([self.packet_mods["HED"],self.packet_mods[type],length,self.packet_mods["SOP"],payload,checksum,self.packet_mods["EOP"]])
elif type == "DtD":
if payload in self.packet_mods:
return bytes([self.packet_mods["HED"],self.packet_mods[type],length,self.packet_mods["SOP"],self.packet_mods[payload],checksum,self.packet_mods["EOP"]])
else:
return bytes([self.packet_mods["HED"],self.packet_mods[type],length,self.packet_mods["SOP"],payload,checksum,self.packet_mods["EOP"]])
def send_packet(self, data, packet_type="data"):
self.socket.send(self.packet_template(packet_type,data))
def calculate_checksum(self, data):
checksum = 0
for i in range(len(data)):
checksum += data[i]
return math.mod(checksum, 256)
def receive_loop(self):
while True:
try:
data = self.socket.recv(self.packet_size)
if not data:
break
self.handle_received_data(data)
except Exception as e:
print(f"Error in receive_loop: {e}")
break
def handle_received_data(self, data):
payload = data[data.index(self.packet_mods["SOP"])+1:data.index(self.packet_mods["EOP"])-2]
rec_check = data[data.index(self.packet_mods["EOP"])-1].decode()
calc_check = self.calculate_checksum(payload)
if rec_check != calc_check:
self.send_packet("ERR","DtD")
elif rec_check == calc_check:
self.buffer.extend(data) # Append received data to the buffer
def process_buffer(self):
if self.busy:
self.send_packet("OCK", packet_type="data")
return
decoded = []
for i in range(len(self.buffer),0,-1):
payload = i[i.index(self.packet_mods["SOP"])+1:i.index(self.packet_mods["EOP"])-2]
rec_check = i[i.index(self.packet_mods["EOP"])-1].decode()
type = i[i.index(self.packet_mods["HED"])+1]
event = self.buffer[i-1]
if event in self.commands.values():
if self.ign_count > 0:
self.ign_count -= 1
elif event == self.commands["ACK"]:
self.packet_number_ack += 1
self.events.trigger("ACK")
elif event == self.commands["NAK"]:
self.packet_number_err += 1
self.events.trigger("NAK")
elif event == self.commands["ABO"]:
self.packet_number_err += 1
self.events.trigger("ABO")
elif event == self.commands["OCK"]:
self.events.trigger("OCK")
elif event == self.commands["ERR"]:
self.packet_number_err += 1
self.events.trigger("ERR")
elif event == self.commands["IGN"]:
self.ign_count += 1
self.events.trigger("IGN")
decoded.append({"type":type,"payload":payload,"checksum":rec_check})
return decoded
m = WModem("127.0.0.1","1701")
m.events.listen("ACK",lambda: print("ACK"))
m.connect()
while True:
time.sleep(1)
print("waiting...")