This PR adds the packet stack for the CCSDS File Delivery Protocol.
It also refactors the existing TMTC infastructure to allow sending
of CFDP packets to the CCSDS handlers.
This includes the whole PDU (Protocol Data Unit) stack:
- File Data PDUs
and all file directive PDUs
- ACK PDU
- NAK PDU
- Metadata PDU
- Finished PDU
- Prompt PDU
- Keep Alive PDU
- EOF PDU
The PR includes a full set of unittests for the packet stack
with a coverage of 90+ %.
The refactoring of the existing TMTC infastructure includes non-ideal
solutions like diamond inheritance.
Avoiding this solution would require refactoring the packet stack.
This would be a good idea anyway because the existing stack is tightly
coupled to the FSFW, making reuse more difficult if only the stack is
planned to be used without the store functionalities etc.
The PDU implementation provided here is only weakly coupled to the FSFW,
only using components like returnvalues or the Serialization modules.
There are dedicated serializers and deserializers, which also helps in
creating small focused modules which are easy to test.
Some of the modules here were provied by Matthias Tompert.
This refactoring keeps the TCP connection opened until the client closes
it. It also increased the robustness of the TCP reception.
Because TCP is stream based and usually applied to newline separated
data, a special way to handle binary space packets is required.
The new SpacePacketParser class takes care of this by taking TC packet
IDs as as optional start markers to parse for space packets in a given
buffer.
The refactored TCP server uses a ring buffer, a reception buffer and the
new parser to extract space packets from a stream in a safer way.
