Validate server and client IP address

[charlesbvll]

What does this implement/fix? Explain your changes.

The server and client IPs are given as strings but are not validated. This PR adds a utility function to parse IPv4 and IPv6 addresses.

[charlesbvll]

@danieljanes Should we use an external library like this one to check if a string is a valid domain? Otherwise we could also check with requests that the URL not only is correct but also exists on the internet:

    try:
        response = requests.get(url)
        print("URL is valid and exists on the internet")
    except requests.ConnectionError as exception:
        print("URL does not exist on Internet")

[tanertopal]

@danieljanes as far as I can see this looks good. Let's merge it.