Peter M. Groen / libmodbus

This change has introduced by 83c34102.
Fix unit tests on some systems.

Function modbus_receive_from has no implementation in the library and is not used anywhere.

Protects against crafted write requests with a large quantity but a small
byte count. If address + quantity was in the mapping space of the server
and quantity greater than the response size, it was possible to crash
the server.

The sleep/flush sequence improves the handling of following requests.

Thank you Petr Gladkiy and MarjanTomas.
Sorry for the delay...

From Michael Heimpold:
Just a nitpick: the INADDR_* macros are defined in host byte order,
compare INADDR_LOOPBACK. So it would be reasonable to wrap this with
htonl(INADDR_ANY). However, every experienced socket programmer should
know that INADDR_ANY equals 0.0.0.0, passing it through htonl does not
have any effect.

- protect against NULL IP address BTW
- update documentation

- allow an empty string or NULL for node argument
- protect against NULL in service argument
- new test for NULL service
- update documentation

Thanks to Marjan Tomas

Change API of function for libmodbus v3.2.0

Thanks to Perry Kundert for bug report and initial patches.

- 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

Thank you AlexMaz.

https://www.securecoding.cert.org/confluence/display/seccode/DCL37-C.+Do+not+declare+or+define+a+reserved+identifier
Not applied to libmodbus constants for now...

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

The index variable shadowed a variable in the standard library causing
warnings. Renaming the 'index' variable to 'idx' resolves the issue.

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.