DONEwhen handshake is completeNEED_READwhen waiting for data from peerNEED_WRITEwhen data needs to be sentERRORon handshake failure
NativeDtlsEngine.handshake
TlsProgress handshake() @safePerform or continue the DTLS handshake.
For clients, this initiates or continues the handshake with the server. For servers, this is typically not called directly; use processDatagram instead.
Returns
TlsProgress indicating the handshake status: