Investigation of empty ServiceIP on HydraRouter dashboard

[cjus]

The check for ServiceIP == null or string.Empty fails on AWS Fargate (and perhaps other environments).
The if statement returns false and so ServiceIP isn't being set to a value.

https://github.com/pnxtech/Hydra4Net-Development/blob/master/Hydra4NET/Hydra.cs#L144

              if (ServiceIP == null || ServiceIP == string.Empty)
              {
                  using Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, 0);
                  socket.Connect("8.8.8.8", 65530);
                  if (socket.LocalEndPoint is IPEndPoint endPoint)
                  {
                      ServiceIP = endPoint.Address.ToString();
                  }
              }

I think we should replace the contents of the if (ServiceIP == null || ServiceIP == string.Empty) statement with:

   var name = Dns.GetHostName();
   ServiceIP = Dns.GetHostEntry(name).AddressList.FirstOrDefault(x => x.AddressFamily == AddressFamily.InterNetwork);

[mrf460]

this makes sense, although we can probably simplify further by adding something like below (since the bottom statement is also filtering by AddressFamily.InterNetwork)

var name = Dns.GetHostName();
var ips =  = Dns.GetHostEntry(name).AddressList.Where(x => x.AddressFamily == AddressFamily.InterNetwork);

if(string.IsNullOrWhiteSpace(ServiceIP))
{
    ServiceIP = ips.FirstOrDefault();
}
else if (ServiceIP.Contains(".") && ServiceIP.Contains("*"))
{
    // then IP address field specifies a pattern match
    int starPoint = ServiceIP.IndexOf("*");
    string pattern = ServiceIP.Substring(0, starPoint);
    ServiceIP = ips.FirstOrDefault(i=>i.StartsWith(pattern));
}

[mrf460]

we can also probably put this in a function, possibly with try/catch to prevent the Fargate issue we saw before? unless you'd rather it throw in that situation

[cjus]

@mrf460 Love a controlled demolition... so try/catch with a re-throw.

[mrf460]

We can do that too. I was thinking catch if we don't want InitAsync to fail, but either way. We could wrap it in an easier to understand exception at least.

On a similar note, that if the user puts in an invalid ServiceIP address? Should we be checking that it exists? And what if no ServiceIP is found for whatever reason?