encode: fragment MF flag

[yoursunny]

As of 09c2bb0, MF flag in ndn-riot fragmentation header has ambiguous interpretations.

ndn_fragmenter_fragment function sets MF flag to 1 on the last fragment:

if (is_last)
  fragmented[0] |= NDN_FRAG_MF_MASK;

ndn_frag_assembler_assemble_frag function expects MF flag to be 0 on the last fragment:

uint8_t mf = frag[0] & NDN_FRAG_MF_MASK;
if (mf == 0) {
  assembler->is_finished = 1;
}

It’s necessary to define the fragmentation protocol in the wiki, and then update implementation accordingly.

[tianyuan129]

Thanks for pointing out the MF flag interpretation problem. bc40bb5 will address this issue. Fragmentation protocol's definition is added to the wiki page now.

[yoursunny]

Great. NFD Feature 4814 is to add the same fragmentation to NFD, enabling interop.