Mbedtls_ssl_close_notify() not correctly cleanup up the handshake process

Mbed TLS
1

I am testing out re connection attempts with mbedTLS. To do this I physically disconnect my Ethernet and plug it back in.
When the Ethernet is physically disconnected the code calls mbedtls_ssl_close_notify() which returns 0.
The problem is when I try to do mbedtls_ssl_handshake() again the state of handshake is in MBEDTLS_SSL_HANDSHAKE_OVER. Thus, it never does the handshake because the method mbedtls_ssl_handshake() only does it if it’s handshake is NOT over.

To get the handshake to run again I have had to call mbedtls_ssl_session_reset() after I call mbedtls_ssl_close_notify() regardless of the mbedtls_ssl_close_notify() return code.

What is the correct process for disconnecting the TLS session?

2

Hi,
Since your connection was not gracefully closed, it is reasonable that the states would be undefined.

Your solution is valid, if you want to negotiate a new TLS handshake.
Have you considered doing session resumption? Please follow the ssl_client2 example on how it deals with reconnecting to a server.
Regards,
Mbed TLS Team member
Ron