A DESCRIPTION OF THE PROBLEM :
Background

DTLS_Client is written in Java with jdk11 build 11+28 and using the classes of javax.net.ssl package.
DTLS_Server is written in C language using Openssl library 1.0.2q and it implements only DTLS v1.0 protocol [RFC4347]

In attach there is the handshake session between DTLS_Client and DTLS_Server (see picture JDK_11_DTLS_Client_handshake.png)



Description
When DTLS_Client, during the handshake, receives from DTLS_Server the message flight #4 (see raw 4 in the picture JDK_11_DTLS_Client_handshake),
it doesn't send the message flight #5:
Certificate
ClientKeyExchange
CertificateVerify
ChangeCipherSpec
Finished
  
After 1 sec (see raw 5 in the picture) the DTLS_Server, as described in the RFC, retransmits the
messages of flight #4 separately/one by one (see raws 5-8 in the picture) the messages, in this case
the DTLS_Client sends the messages of flight #5 separately/one by one (see raws 9-13 in the picture JDK_11_DTLS_Client_handshake) to DTLS server.

My question is:
when DTLS_Server receives the packet with the message flight #4 from socket,
is it correct to pass the complete packet (flight #4 with all messages inside) to the
SSLEngine for the unwrap (engine.unwrap(iNet,iApp) method) ?
Or should it be splitted in 4 packets before passing them to the SSLEngine
for the unwrap (engine.unwrap(iNet,iApp) method) ?
So, is the handling of the fligth messages demanded to the application or is there any setting to
instruct the SSLEngine to handle them ?
 
  
We have also performed another test replacing the DTLS_Client, above mentioned, with Openssl test
client (openssl s_client) (see picture DTLS_server_tested_with_openssl_s_client.png)
and in this case the handshake is succesfully completed.



FREQUENCY : always