SNMPv3 over DTLS

[kdurkin77]

Updated to use DTLS2.Net to allow for SNMPv3 over DTLS. I updated DTLS.Net but since they haven't been responding to pull requests or issues I had use it from my fork and called it DTLS2.Net.

TSM doesn't use the Security Parameters part of the message, so set up SecurityParameters to have a default and Header, GetRequestMessage, and MessageFactory to not require them.

Added the SecurityModel enum to allow for either TSM or USM, keeping USM default. This required new constructors in GetRequestMessage to take in the SecurityModel

Test example:

var vList = new List<Variable>() { new Variable(new ObjectIdentifier("1.3.6.1.2.1.1.3.0")) };
var receiver = new IPEndPoint(ip, port);
var auth = TsmAuthenticationProvider.Instance;
IPrivacyProvider priv = new TsmPrivacyProvider(auth);

using var store = new X509Store(StoreName.My, StoreLocation.CurrentUser);
store.Open(OpenFlags.ReadOnly);
var myCertCollection = store.Certificates.Find(X509FindType.FindByThumbprint, "", true);

var chain = new X509Chain();
chain.Build(myCertCollection[0]);

var client = new Client(new IPEndPoint(IPAddress.Any, 0));
client.LoadX509Certificate(chain);
client.SupportedCipherSuites.Add(TCipherSuite.TLS_RSA_WITH_AES_256_CBC_SHA);

var request = new GetRequestMessage(VersionCode.V3, Messenger.NextMessageId, Messenger.NextRequestId, new OctetString(user), new OctetString(string.Empty), vList, priv, Messenger.MaxMessageSize);
var reply = request.GetSecureResponse(timeout, receiver, client);

foreach (var v in reply.Pdu().Variables)
{
	Console.WriteLine($"RESPONSE: {v}");
}

[kdurkin77]

I believe I have updated everything you've asked for except for the 2 I've asked for clarification on. Please let me know if there's anything further, and thank you for getting back to me so quickly

[kdurkin77]

Do you have a round about ETA on when this could be released?

[lextm]

Nope. No ETA at this moment. I am trying to set up a local lab environment to test out the changes, so it can take a relatively long period.

[kdurkin77]

Understood, thank you!

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