Some external modems have an internal TLSSocket implementation which can be used
instead of mbedtls based TLSSocket. Using offloaded TLSSocket can result in
significantly reduced ROM usage.
Offloaded TLSSocket can be enabled by enabling "nsapi.offload-tlssocket" and the used
network stack (e.g. cellular modem's CellularStack class) must support the setsockopt's
defined in nsapi_types.h.
Compared to original mbedtls based TLSSocket, offloaded TLSSocket brings in one significant
API limitation. Offloaded TLSSocket requires setting of certificates and keys after open()
and before connect() calls, where mbedtls based TLSSocket allows setting these before open()
call.
DTLSSocketWrapper is equivalent of TLSSocketWrapper but uses datagram mode
and timers for handling Mbed TLS timeouts.
Non-blocking connections were not working earlier, now fixed for both
secure socket modes.
Transport is a member of TLSSocket which is derived from TLSSocketWrapper.
Make sure that TLSSocketWrapper::close() is called before the transport is
destroyed.
Provide TLSSocket implementation. This implementation allows TLSSocket
to wrap around any existing socket. Currently only TLS supported. DTLS
not yet implemented.
Design document also provided with the implementation.
Documentation submitted to Mbed OS handbook.
Kimmo Vaisanen
Seppo Takalo