Pflua/Snabb integration

[kbara]

This branch aims to understand and clean up the work that's gone into merging pflua into Snabb.

It appears that the following work:

%  sudo ./snabb snsh -pflua -t apps.packet_filter.packet_filter_test
link report
6 sent on packet_filter1.output -> sink1.input (loss rate: 0%))
161 sent on source1.output -> packet_filter1.input (loss rate: 0%))
19 sent on packet_filter2.output -> sink2.input (loss rate: 0%))
43 sent on source2.output -> packet_filter2.input (loss rate: 0%))
selftest passed

%  sudo ./snabb snsh -t apps.packet_filter.packet_filter     
link report
6 sent on packet_filter1.output -> sink1.input (loss rate: 0%))
161 sent on source1.output -> packet_filter1.input (loss rate: 0%))
19 sent on packet_filter2.output -> sink2.input (loss rate: 0%))
43 sent on source2.output -> packet_filter2.input (loss rate: 0%))
link report
161 sent on source1.output -> statefull_pass1.input (loss rate: 0%))
43 sent on source2.output -> statefull_pass2.input (loss rate: 0%))
36 sent on statefull_pass2.output -> sink2.input (loss rate: 0%))
6 sent on statefull_pass1.output -> sink1.input (loss rate: 0%))
selftest passed

What's been done:

1. Check out https://github.com/dpino/snabbswitch.git
2. git checkout snabb-pflua
3. make
4. Check it works, as per Snabb pflua integration dpino/snabb#1
   4a) cd src
   4b) check the default packet filter
   NOTE: this is not packet_filter_test, mentioned on Snabb pflua integration dpino/snabb#1
   sudo ./snabb snsh -t apps.packet_filter.packet_filter
   4c) sudo ./snabb snsh -t apps.packet_filter.packet_filter_benchmark
   4d) sudo ./snabb snsh -pflua -t apps.packet_filter.packet_filter_benchmark
5. Rebasing onto upstream master
6. Removing core.buffer require and call; it's obsolete and broken.

Note: 'sudo make test' fails, because src/apps/packet_filter/packet_filter_test.lua is known broken:
"function selftest ()
-- Temporarily disabled:
-- Packet filter selftest is failing in."
Why?

Note:
sudo ./snabb snsh -pflua -t apps.packet_filter.packet_filter
sudo ./snabb snsh -pflua -t apps.packet_filter.packet_filter_test
both fail originally, and the second passes with 0a66ad6.
The first fails with
lib/pcap/pcap.lua:82: undeclared or implicit tag 'pcap_file'
The second originally fails, as it does without -pflua, with:
apps/packet_filter/packet_filter_test.lua:11: module 'core.buffer' not found:
(this is fixed in 0a66ad6).

This error dates back to the second patch in the series:
f2041a7, 'Add new pflua packet filtering application'

Questions:
a) Why isn't pflua set up as a submodule within Snabb? It's under deps, but not a submodule.
b) What's the status of apps/packet_filter/conntrack.lua?
c) Why is packet_filter_test.lua broken without -pflua?

[kbara]

Oops, this was a pull-request against the wrong reposity; it was supposed to be WIP notes elsewhere. Apologies.