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client.py
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176 lines (159 loc) · 6.73 KB
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import sys
import time
import lib.connection
import lib.segment as segment
from lib.segment import Segment
from lib.utils.logger import Logger
WINDOW_SIZE = 4
class Client:
def __init__(self):
# Initialize client
self.ip = "localhost"
self.port = None
self.server_addr = None
self.connection = None
self.file_path = None
self.file_buffer = []
# Utility
self.logger = Logger()
def connect_to_server(self, client_port, server_port, file_path):
# Initialize client
self.port = client_port
self.server_addr = ("localhost", 12345)
self.file_path = file_path
self.connection = lib.connection.Connection(self.ip, self.port)
# Connect to server
try:
# Initialize segment
req = Segment()
req.header['seq_num'] = 1
req.header['ack_num'] = 2
req.set_flag(["syn"])
req.data['payload'] = b"Pen connect bang"
req.update_checksum()
# Send segment
self.logger.log_info(1, f"Sending request to server...")
self.connection.send(req, self.server_addr)
self.logger.log_info(0, "Request sent successfully")
except Exception as e:
# self.logger.log_err(0, e)
sys.exit(1)
def three_way_handshake(self):
# Three Way Handshake, client-side
while True:
self.logger.log_info(1, "Handshaking with server...")
# Listening SYN
self.connection.set_timeout(999)
try:
self.logger.log_info(0, "Listening SYN")
syn, addr = self.connection.listen_single_segment()
self.logger.log_info(0, "SYN received")
syn_flag = syn.get_flag()
syn_flag = syn_flag.get_flag_bytes()
if syn_flag == segment.SYN_FLAG:
syn_ack = Segment()
syn_ack.set_flag(["syn", "ack"])
break
except Exception as e:
self.logger.log_err(0, e)
while True:
# Send SYN-ACK
self.logger.log_info(0, "Sending SYN-ACK")
self.connection.send(syn_ack, self.server_addr)
self.logger.log_info(0, "SYN-ACK sent")
# Listening ACK
self.connection.set_timeout(1)
try:
self.logger.log_info(0, "Listening ACK")
ack, addr = self.connection.listen_single_segment()
self.logger.log_info(0, "ACK received")
ack_flag = ack.get_flag()
ack_flag = ack_flag.get_flag_bytes()
if ack_flag == segment.ACK_FLAG:
self.logger.log_info(1, "Handshake successful")
return True
else:
self.logger.log_err(0, "Handshake failed")
except Exception as e:
self.logger.log_err(0, e)
def listen_file_transfer(self):
# File transfer, client-side
self.logger.log_info(1, "Listening for file transfer...")
seq_num = 0
current_seq_num = 0
sm = WINDOW_SIZE - 1
while True :
self.connection.set_timeout(99999)
try:
# Listening segment
self.logger.log_info(0, "Listening segment")
segment, addr = self.connection.listen_single_segment()
segment_flag = segment.get_flag()
seq_num = segment.get_header()['seq_num']
print ("current_seq_num", current_seq_num)
print ("seq_num", seq_num)
self.logger.log_info(0, "Segment" + str(seq_num) + " received")
if segment_flag.fin:
self.logger.log_info(0, "File Received")
file = b''.join(self.file_buffer)
with open(self.file_path, 'wb') as f:
f.write(file)
timeout = time.time() + 4
ack_received = False
while time.time() < timeout:
ack = Segment()
ack.set_flag(["fin", "ack"])
self.connection.send(ack, self.server_addr)
self.logger.log_info(0, "FIN-ACK sent")
self.connection.set_timeout(1)
try:
ack, addr = self.connection.listen_single_segment()
ack_flag = ack.get_flag()
if ack_flag.ack:
self.logger.log_info(0, "ACK received")
self.logger.log_info(0, "Closing connection...")
self.connection.close_socket()
ack_received = True
break
except Exception as e:
self.logger.log_err(0, e)
if not ack_received:
self.logger.log_info(0, "ACK not received")
self.logger.log_info(0, "Closing connection...")
break
if seq_num == current_seq_num:
self.file_buffer.append(segment.get_payload())
ack = Segment()
ack.set_flag(["ack"])
ack.set_ack_num(seq_num)
self.connection.send(ack, self.server_addr)
self.logger.log_info(0, "ACK" + str(current_seq_num) + " sent")
current_seq_num += 1
else:
if (current_seq_num - seq_num >= sm):
ack = Segment()
ack.set_flag(["ack"])
ack.set_ack_num(seq_num)
self.connection.send(ack, self.server_addr)
self.logger.log_info(0, "Segment" + str(seq_num) + " is out of window")
else:
self.logger.log_info(0, "Segment" + str(seq_num) + " refused")
except Exception as e:
# self.logger.log_err(0, e)
break
if __name__ == '__main__':
# Argument validation
if len(sys.argv) != 4:
print("Usage: python client.py <client port> <server port> <file path>")
sys.exit(1)
client_port = int(sys.argv[1])
server_port = int(sys.argv[2])
file_path = sys.argv[3]
# Client main
client = Client()
client.connect_to_server(client_port, server_port, file_path)
connection = client.connection
ack, addr = connection.listen_single_segment()
client.three_way_handshake()
client.listen_file_transfer()
sys.exit(0)