Peter M. Groen / libmodbus

Change API of function for libmodbus v3.2.0

- add byte timeout tests (TCP backend only)
- update and improve documentation
- long timeout values are now uint32_t so it changes the API
  to disable byte timeout

- update documentation
- 5 new tests
- updated NEWS file
- avoid include of time.h

It's strongly recommended to update your libmodbus library if you
use it in a slave/server application in a not trusted environment.

Debian package of libmodbus 3.0.4 already contains a patch to
mitigate the exploit but the patch isn't as strong than this one.

Thank you very much James Nutaro.

- change return argument from void to int
- update documentation

Thanks to Karl Palsson.

Thanks Tobias Doerffel.

Thanks to Carlos Tangerino

Thanks to Stefan Finzel for the bug report

Original patch for new connect function by Thomas Stalder.

- export new symbols to create specific behavior (RTU)
- the flag can't only be set by slaves
- new tests

Warning, modbus_receive returns 0 when a query is ignored.

- function removed from TCP and RTU code and from backend structure
- updated documentation
- updated examples

- new function _modbus_rtu_pre_check_confirmation
- new special test value to trigger an invalid response
- add unit test to cover invalid TID too

Thanks to Andrea Mattia

Add macros in libmodbus.txt and:
- modbus_get_byte_from_bits.txt
- modbus_get_float.txt
- modbus_reply.txt
- modbus_reply_exception.txt
- modbus_set_bits_from_byte.txt
- modbus_set_bits_from_bytes.txt
- modbus_set_float.txt

The function name was confusing because the write operation is performed
before the read. Take care to swap the arguments in the migration process.

Avoid incompatibility with GPLv2 program. This change has been approved by
Tobias Doerffel, Florian octo Forster and Hannu Vuolasaho.

The two modes are complementary, MODBUS_ERROR_RECOVERY_LINK handles
errors at data link level (bad file descriptor, timeout, etc) and
MODBUS_ERROR_RECOVERY_PROTOCOL checks Modbus error (eg. invalid
function code or trame length).

This change introduces the use of the Sleep function for Windows.
Some duplicated code has been moved from backends to modbus core.
A new debug message is now available when a flush occurs.

The unit tests are now based on this error recovery code.