Remove prototype for function that is never defined.

Signed-off-by: Mike Szczys <[email protected]>

Use a compile-time constant for the length of the CoAP token (in bytes).

Signed-off-by: Mike Szczys <[email protected]>

Add golioth_coap_next_token() to randomly generate the first token and
increment a stored value for all future tokens.

Signed-off-by: Mike Szczys <[email protected]>

Squash before merging

Signed-off-by: Mike Szczys <[email protected]>

Squash before merging

Signed-off-by: Mike Szczys <[email protected]>

Squash before merge

Signed-off-by: Mike Szczys <[email protected]>

Squash before merging

Signed-off-by: Mike Szczys <[email protected]>

TODO: unit tests for RPC

Signed-off-by: Mike Szczys <[email protected]>

Squash before merge

Signed-off-by: Mike Szczys <[email protected]>

Squash before merge.

Signed-off-by: Mike Szczys <[email protected]>

Squash before merge

Signed-off-by: Mike Szczys <[email protected]>

Squah before merging

Signed-off-by: Mike Szczys <[email protected]>

Tokens are now generated by the calling function. The same token will
automatically be used for each subsequent block because of the
blockwise_transfer context struct.

The workaround that overwrite the initial token for these requests is no
longer necessary and has been removed.

Squash before merging

Signed-off-by: Mike Szczys <[email protected]>

Directly use the token stored in the request message instead of creating a
new one. Remove the block_token storage from the client struct.

Squash before merging

Signed-off-by: Mike Szczys <[email protected]>

CoAP tokens are now generated by the Golioth SDK outside of the libcoap
library. The call to golioth_sys_srand() in the libcoap client is no longer
crucial as it will be called by Golioth's token generation function.

However, the random seed initialization for libcoap's token generation
should still be called just to ensure token generation is ready in the rare
(and currently unanticipated) case where libcoap internally fetches a new
token. One place that this is likely to occur is when libcoap uses etags.
We are not currently using etags in our implementation.

Use dynamically allocated memory to seed the token. This value will be
stored in the libcoap coap_session_t struct and the seed array will no
longer be needed.

Note, both Golioth and libcoap token generation uses a simple increment
after generating the initial random token. Avoid collision by getting a
token from Golioth and incrementing it by half its max value before seeding
libcoap.

Signed-off-by: Mike Szczys <[email protected]>

This value is now available as a compile-time constant.

Squash before merge

Signed-off-by: Mike Szczys <[email protected]>

Remove the token_len parameter as the compile-time define is now used
throughout the SDK.

Change the appearance and type of the token param to match what is used
with other functions that create coap requests.

Signed-off-by: Mike Szczys <[email protected]>