import select
import socket
import sys


def main():
    udp_s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    udp_s.bind(("127.0.0.1", 0))
    server_addr = ("127.0.0.1", 1234)

    while True:
        rsocks = select.select([udp_s, sys.stdin], [], [])[0]

        for sock in rsocks:
            if sock == udp_s:
                b_data, addr = udp_s.recvfrom(4096)
                sys.stdout.write(f"-> {b_data.decode('utf-8')}")
            elif sock == sys.stdin:
                print('<- ', end='')
                msg = sys.stdin.readline()
                udp_s.sendto(msg.encode("utf-8"), server_addr)


if __name__ == '__main__':
    main()