implementation not resistant to duplicate packets

[bmegli]

Looking at the implementation I see that the library doesn't handle duplicate UDP packets correctly.

There is no guarantee that UDP packets will not arrive multiple times.

Looking at the code here:

   memcpy(m->collected.data + udp.packet*PACKET_MAX_PAYLOAD, udp.data, udp.size);

   ++m->collected.collected_packets;
   m->collected.actual_size += udp.size;

   if(m->collected.collected_packets == udp.packets)

we see that duplicate packets are not taken into account and may brake packet collection or in the worst case, if they slip through sanity checks, we could interpret incomplete frame as complete.

The correct way to do it is to:

• for each frame
• keep track of its collected packets (by nr)
• only if we have all parts (tracked by packet number)
• return full frame

Possibly related to UNHVD#10,

[bmegli]

This is fixable in around 10 lines of code.

Nonetheless this has to wait, at least until merging multi-frame support to master.

[bmegli]

This also fulfills requirements for HVS#5