Add counter to the stream reassembly engine to count stream gaps. Stream gaps
are the result of missing packets (usually due to packet loss). This missing
data stops the reassembly for the app layer.
Added stream counters:
- tcp.reassembly_memuse -- current memory use by reassembly in bytes
- tcp.memuse -- current memory use by stream tracking in bytes
- tcp.reused_ssn -- ssn reused by new session with identical tuple
- tcp.no_flow -- TCP packets with no flow - indicating flow engine memory at its limits
The stream engine memory handling needed updating as it didn't scale. Changes:
- pools can now be initialized to size 0, meaning unlimited
- stream engine uses a memcap setting. Sessions, segments and aldata is part
of this, app layer state isn't.
- memory is accounted using a global int that is spinlocked.
- a counter for sessions that have not been picked up because of memcap was
added.
- all reassembly errors are converted to debug msgs.
- Implement "closing" state in flow.
- Add protocol specific timeouts.
- Lots of stream tracking updates, fixing a lot of out of window issues.
- Stream reassembly fixes.
- Implement a new IDS runmode with 4 stream and detect threads.
- Added a BUG_ON macro that aborts the engine if the expression is true.
- Better balance the flow queue handler for traffic that doesn't have flow (like icmp currently).
- Simplify application level protocol in the Tcp Session.
- Add some debugging memory counters.