Allow to inspect UDP messages and check for GPRS, NS, BSSGP
and then filter LLC frames. Parsing the vL datastructure with
the libpcap syntax is a pain. It could be done using BPF but
we do not want to use bpf asm to specify the entire ruleset.
I looked into using libepan/libwireshark but this has memory
issues and is painful too. So let's parse UDP, NS, BSSGP using
the info we already have. I tried a bit of editcap to generate
a bit of broken data. The length check might still be bad.
I used my crash_20100602.pcap file to count the LLC frames we
detect and compare that to wireshark it ended with the right
number.
pcap add-filter gprs
can be used to enable the new filtering option after the OS
has received the packet.
Fixes: ONW#1314
Holger Hans Peter Freyther
Sylvain Munaut