Check if unpacking headers will overflow buffer

More defensive if a bad packet somehow gets into the uncompress stage.
Check if buffer is allocated before using.

This prevents a packet fragment from using a buffer that wasn't
initialized by the first fragment in the series. This shouldn't happen,
but if somehow the first fragment isn't received but a later one is, the
application won't segfault.
Removed unnecessary printfs
More progress in implementing SLAAC
changes for the rpi