ntptime spoof or bad response shape

[Tangerino]

Current code

def time():
    NTP_QUERY = bytearray(48)
    NTP_QUERY[0] = 0x1B
    addr = socket.getaddrinfo(host, 123)[0][-1]
    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    try:
        s.settimeout(timeout)
        s.sendto(NTP_QUERY, addr)
        msg = s.recv(48)
    finally:
        s.close()
    val = struct.unpack("!I", msg[40:44])[0]

Proposal

    msg, src = s.recvfrom(48)
    # Right host AND a full 48-byte reply. Skip spoofed/runt packets
    if src[0] == addr[0] and len(msg) >= 48:
        # got the response
    else:
        # not from the right host or packet too short
        # that may break on -> val = struct.unpack("!I", msg[40:44])[0]