#106 Add a build flag to indicate if user need to be informed on every received PD packet

[Chuck Lee]

While build ECSP based on TCNOpen, the built-in redundant content filter of PD will cause issue on some edge cases, including:

1. If ED 1 sends TCN-DNS request for some TCN-URI, then ED 2 sends same request as ED 1, the request of ED 2 will be ignored.
2. Implementation PD timeout mechanism without using built-in timeout mechanism, the timeout will always be triggered because application didn't get informed about receptance of PD.

So we like to add a build flag to indicate if user need to be informed on every received PD packet, i.e., disable the redundant content filtering.
Attachment is the proposed patch.

[Bernd Löhr]

Actually this could also be useful for other situations (SDT?).
I would rather prefer a configuration-time flag than a compiler flag to be able to handle both cases in the same implementation (TRDP_FLAGS_T). This could relieve the application if there are higher cycled packets around.

[Bernd Löhr]

XML definition needs to be updated

[Bernd Löhr]

XML/XSD: The callback-tag can now be 'on', 'off' & 'always'. The latter will enable callbacks on reception of a PD, regardless if content changed or not.
Additional packet flag 0x10 (TRDP_FLAGS_FORCE_CB).
Setting of a callback function pointer is mandatory, of course.