Topic: DTLS negotiation fails if packets arrive in wrong order
We are evaluating wolfSSL embedded SSL version 2.4.0 for DTLS and so far it works great but yesterday we found something strange. It looks like if the UDP packets does not arrive in the expected order to the client, the client fails to complete the negotiation.
The UDP packets that are sent between the client (c) and the server (s) are in our test case:
1. c->s client_hello
2. s->c hello_verify_request
3. c->s client_hello
4. s->c server_hello
5. c->s certificate
... (the rest of the negiotion is not included here)
And the above works very well. The problem is if some packets in the same flight in step 4 arrives to the client in wrong order. As an example, if the packets in step 4 arrives in this order at the client:
Then, the client will fail to continue the negotiation process and will never send its certificate back to the server. Can you reproduce this scenario at your place? Is this a known issue? Is it something that will be fixed?