The dTLS server (1.2) is not handling properly the re-transmissions in case of delay in flight at server side (we see clientKeyExchange before serverKeyExchange and serverHelloDone)

[shreyaaapatil]

We tried to test a scenario that the server has a delay before sending message, so we expect the client to do retransmission, but it seems like the client sends the next flight before getting all the flight for the server (We can see clientKeyExchange before serverKeyExchange and serverHelloDone).

void
CallbacksPSK::tls_emit_data(uint8_t const buf[], size_t const length)
{
    if (nullptr == mEngine) {
        throw std::runtime_error("Null engine pointer!");
    }
   if(mEngine->mIsServer){
       sleep(5);  //delay of 5 sec at server side                             
   }
}

This is not the right behavior according to the RFC, because in case of partial read, we shouldn't move to Sending state.
The same delay when we add it for client side the handshake is getting completed-

if(!mEngine->mIsServer){
       sleep(5);  //delay of 5 sec at client side                             
   }

Is adding delay at server side affecting retransmission behaviour?