cs456/a1/client.py

import socket
import sys

# save values needed to talk to server
saddr = sys.argv[1]
uport = int(sys.argv[2])
rcode = sys.argv[3]
msg = sys.argv[4]

# start udp socket
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

# send msg to server to check rcode
sock.sendto(rcode.encode(),(saddr, uport))

# get reply from server, save the port, then check it
confirmation, newaddr = sock.recvfrom(1024)
rport = confirmation.decode()
sock.sendto(rport.encode(), newaddr)
confirm, neweraddr = sock.recvfrom(1024)

if (confirm.decode() == "correct"):
    # got right port, close UDP connection
    sock.close
    
    # make TCP connection, send msg
    tsock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    tsock.connect((saddr, int(rport)))
    tsock.send(msg.encode())
    
    # get reply, print it, exit
    reply = tsock.recv(1024).decode()
    print("CLIENT_RCV_MSG='", reply, "'", sep="")
    tsock.close()
    sys.exit(0)

else:
    print("Did not confirm the port, giving up.")
    sys.exit(1)