server_address.py

#!/usr/bin/python3

# -----------------------------------------------------------
# Unless explicitly stated otherwise all files in this repository are licensed under the Apache License Version 2.0.
# This product includes software developed at Datadog (https://www.datadoghq.com/).
# Copyright 2019-2020 Datadog, Inc.
# -----------------------------------------------------------

import socket

class ServerAddress():
    def __init__(self, ip, port):
        self.ip = ip
        self.port = port

def get_private_IP_on_subnet(subnet_broadcast: str):
    """
    Returns private IP on a specific local network or `None` if the local network is not reachable.
    """

    s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    try:
        s.connect((subnet_broadcast, 1))
        return ServerAddress(s.getsockname()[0], 8000)
    except:
        return None
    finally:
        s.close()

def get_private_IP():
    """
    Returns private IP on the local network or `None` if the local network is not reachable.
    """

    private_ip = get_private_IP_on_subnet('10.255.255.255')
    if private_ip is not None:
        return private_ip
    return get_private_IP_on_subnet('192.168.255.255')

def get_localhost():
    """
    Returns localhost address.
    """

    return ServerAddress('127.0.0.1', 8000)

def get_best_server_address():
    """
    Returns private IP if possible, localhost otherwise.
    """

    private_ip = get_private_IP()
    return private_ip if private_ip is not None else get_localhost()

if __name__ == "__main__":
    address = get_best_server_address()
    print("{ip}:{port}".format( ip = address.ip, port = address.port))