Treat the case where a field is omitted identical to the case
where an empty array is given. In particular
- data_length == 0 is allowed now and identical to giving no data.
- nonce can be omitted to indicate nonce value 0.
I still do not allow to omit gas_limit and gas_price; gas_limit
cannot be zero and transactions with zero gas_price will not be
mined. You can still set it explicitly to zero by giving the
empty array, though.
See trezor/trezor-mcu#143.
Every 4294967295 milliseconds (2 ^ 32 - 1), system_millis will overflow.
This means that every 49.71 days, system_millis will reset to zero.
Comparisons like `system_millis < (system_millis + 1)` would fail if the
latter had overflown and the former had not.
This is non-critical because the worst case is that one second could be
skipped or the screen could lock early.
This poses no threat to the exponential backoff used for protection
against brute force.
Removed `usbDelay(uint32_t cycles)`, added `usbSleep(uint32_t millis)`
The same method signature could cause silent code breakage at runtime,
as opposed to noisy code breakage at compile time which is the better
kind.
This patch adds calls to usbPoll in the progress callback. This
should address #98.
We call usbDelay instead of Poll, to call usbd_poll several times.
Otherwise it would only handle one event instead of handling all
events that were pending so far. The ugly magic number 5 is a guess.
Note that we also need to set usbTiny, so that we don't recursively
process messages. Since we don't know whether usbTiny is set, we
need to store the old value (especially true for u2f).
This fix also relies on another fix in libopencm3.
Holding confirm button at home screen asks user whether they wish to
lock the TREZOR (clear the cached PIN and passphrase and show the
screensaver). This is identical behaviour to the ClearSession message.
