Hi Simon,

I'll come back to you tomorrow for your questions.
Seems there is some pb with the rebase I made for this patchset.


David

-   Ensure no memory leaks and entropy counter is protected

-   Use ERR_CLSD only for handshake error.   
    This allow better handling of handshake error in application.

-   Call the application sent() callback with usefull len
   
    First calculate and sum TLS overhead when altcp_mbedtls_write() is called.
    Then take care of it when calling application sent callback. Give reveived
    len from inner_conn, minus calculated overhead.

-   Support for saving/restoring session information
   
    According to mbedTLS source code and documentation, calls to
    `mbedtls_ssl_conf_session_cache` and `mbedtls_ssl_conf_session_tickets_cb`
    are only available if mbedTLS is configured for server mode (ie. MBEDTLS_SSL_SRV_C
    is defined). This cannot be used on client mode to resume a previous session.
   
    To allow session reuse in client mode, application must save session parameters
    (including tickets provided by the server if any) after successfull connection
    and restore them before attemting to reconnect. Since `alctp_close()` free the
    structure, it cannot be used to store the required information.
   
    So, two new API were added, directly wrapped to mbedTLS functions, allow application
    to do that by itself.
   
    Also added full declaration of `struct altcp_tls_session` in altcp_tls.h to allow
    easier usage in application when using mbedTLS port.

-   Ensure configuration is properly freed.