#!/usr/bin/env python3
#
#  Copyright (c) 2021, The OpenThread Authors.
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import socket
import sys
import ipaddress

# USAGE: python3 udp_send.py [destination_ipv6] [destination_port] [message] [hop_limit]
# udp_send sends a udp packet to an ipv6 address.


def main():
    args = sys.argv[1:]
    assert len(args) == 4
    destination_ipv6 = args[0]
    destination_port = args[1]
    message = bytes(args[2], 'utf-8')
    hop_limit = int(args[3])
    sock = socket.socket(
        socket.AF_INET6,  # Internet
        socket.SOCK_DGRAM)  # UDP

    address = ipaddress.ip_address(destination_ipv6)
    if address.is_multicast:
        sock.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_MULTICAST_HOPS, hop_limit)
    else:
        sock.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_UNICAST_HOPS, hop_limit)
    sock.sendto(message, (destination_ipv6, int(destination_port)))
    sock.close()


if __name__ == '__main__':
    main()