Compatibility fixes and pyroute2 examples

Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>

* simple_tc shows using just IPRoute
* simple_ipdb shows using IPDB as well, slightly more complicated
 - If the exception handling is done as shown, hangs may result
 - If only IPRoute is used, this shouldn't be the case
Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>

* Add requirement on 'future' package to ensure backwards compatibility
 - If working in dev environment, do 'sudo pip install future'

Note: end-users installing a compiled package with pip should have
future installed as a dependency automatically.
Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>

reduce test time for test_brb and test_brb2

Signed-off-by: Yonghong Song <yhs@plumgrid.com>

Automatically detect key/leaf type in clang

Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>

* Parse the key and leaf types used for table definition, and pass the
  type info back into python using a json transport
* Remove the subscript operator support
* Migrate the tests that are able to drop they Key/Leaf definition. Keep
  it around for the tests that are B/C compatible
Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>

Cleanups for some build/compile failures

Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>

Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>

python commands module is removed in python 3, use subprocess

* Change ftw to nftw, and do depth-first tmpdir cleanup
* Scrub CROSS_COMPILE variable before kbuild_helpers
Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>

Signed-off-by: Yonghong Song <yhs@plumgrid.com>

Yhs dev

Signed-off-by: Yonghong Song <yhs@plumgrid.com>

Signed-off-by: Yonghong Song <yhs@plumgrid.com>

Update readme and FAQs

Remove the BPF_EXPORT macro, use rewriter instead

Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>

Specifically, mention the step to install the kernel image, modules
and headers.

* Add a BFrontentAction to recognize any external linkage function as
  being available for export, and internally set the section attribute.
* Change bpf helpers to be static inline
Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>

Include kernel headers >=4.1 as a prerequisite.

Add kprobe auto-cleanup and header fix

* Add bpf_detach_kprobe helper to libbpf
* Automatically invoke detach at python program exit
* Add "uapi/" to one include in helpers.h
Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>

avoid include file linux/bpf.h in helpers.h

   o use uapi/linux/bpf.h instead
   o to be consistent with kernel/samples/bpf/
Signed-off-by: Yonghong Song <yhs@plumgrid.com>

Add a Learning VLAN program example

* Create a simulation of a physical network with multiple vlans, which
  can accept and distribute connections from multiple clients in
  overlapping subnets. The program will assign to a worker based on mac
  address.
* Remove a hardcoded SO_ATTACH_BPF literal, and fix one spacing
Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>

add another bridge-router-bridge test (test_brb2)

  o router is implemented as a namespace, similar to test_brb.
  o using linux bridge to provide bridge functionality.
    In test_brb, a simple bpf program implemented limited
    bridge functionality.
  o on my local box, test_brb performance is roughly 12% better
    than test_brb2.
Signed-off-by: Yonghong Song <yhs@plumgrid.com>

use 64bit ulonglong to represent mac address

Signed-off-by: Yonghong Song <yhs@plumgrid.com>

use ethernet->src/dst to get mac address instead of primitive load_* …

Signed-off-by: Yonghong Song <yhs@plumgrid.com>

Fix for >32B bpf_pkt_dext calls

add a bridge-router-bridge test with router implemented as a namespace

* Fix the shift which was 4 (bytes) instead of 32 (bits)
* Remove an incorrect ntoh
Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>