- Added non-blocking DNS interface to network interface and
network stack.
- Added caching of DNS replies.
- Added a network stack function to get DNS addresses from stack.
- Added call and call_in hooks to onboard network stack to
allow calling functions from onboard stack context.
- Added support to call and call_in functions to LWIP and
Nanostack.
- Disabled LWIP DNS translator with the exception of DNS
address storage used in DNS address get.
As we've introduced virtual inheritance to support EMACInterface, we can
no longer use C-style casts or static_cast to downcast from
NetworkInterface to more specific types. RTTI is disabled in the
toolchains, so dynamic_cast is unavailables.
Add virtual downcast methods to permit conversions to the 6 derived
classes. Probably only needed for EMACInterface, WiFiInterface and
EthInterface, but handles the set.
nsapi_error_t - enum of errors or 0 for NSAPI_ERROR_OK
nsapi_size_t - unsigned size of data that could be sent
nsapi_size_or_error_t - either a non-negative size or negative error