dht_client.py

import argparse
import socket

def _parse_args():
    parser = argparse.ArgumentParser()
    parser.add_argument("host", type=str, nargs=1, help="the host")
    parser.add_argument("port", type=int, nargs=1, help="the port")
    parser.add_argument("op", type=str, nargs=1, help="the operation name GET/PUT")
    parser.add_argument("key", type=str, nargs=1, help="key", default=[""])
    parser.add_argument("value", type=str, nargs='*', help="value", default=[""])
    args = parser.parse_args()
    return args.host[0], args.port[0], args.op[0], args.key[0], args.value[0]

'''
is_found: indicate if the node is the target node that will deal with the key
host & port is the client address, both of them will be speicified in the first server node
hops(integer): total hops at some stage
op: operation of GET / PUT
k: key
v: value
'''
def build_req(is_found, host, port, hops, op, k, v):
    return str(is_found) + ',' + host + ',' + str(port) + ',' + str(hops) + ',' + op + ',' + k + ',' + v


if __name__ == '__main__':
    host, port, op, k, v = _parse_args()
    msg = build_req(0, "", 0, 1, op, k, v)

    if op.lower() != "get" and op.lower() != "put":
        print ("the operation should be get or put")
        exit() 
    
    if k == "":
        print ("key can't be empty")
        exit()

    if op.lower() == "get" and v != "":
        print ("when op is get, value is not allowed")
        exit()

    print ('send request:', msg, ' to ', (host, port))
    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    sock.bind(("", 11315))
    sock.sendto(str.encode(msg), (host, port))
    resp, server_address = sock.recvfrom(4096)
    print ('response received:', resp, ' from ', server_address)