fed8da5072
this code is from kernel bpf selftests xdp synproxy, removed the tc part for simplicity, shows an exmaple of using libxdp to attach xdp synproxy program on network interface. if port is not in allowed ports, the packet will be dropped by xdp synproxy by default, this would break tcp connections to ports that user does not want to do synproxy, change the default to allow connection pass through. Signed-off-by: Vincent Li <vincent.mc.li@gmail.com>
NOTICE
This directory contains include header files needed to compile BPF programs.
The files are either copied from the kernel source (in subdir linux/) or "shadow" files that contain useful defines that are often used in kernel headers.
For example bpf/compiler.h contains practical compile macros
like READ_ONCE and WRITE_ONCE with verifier workarounds via
bpf_barrier(). And the likely() + unlikely() annotations.
The include file linux/bpf.h is the most central file that all
BPF (kernel-side) programs include. It is maintained in this directory,
because this project knows what BPF features it uses, which makes the update
cycle tied to the project itself. We prefer not to depend on the OS distro
kernel headers version of this file. (Hint, due to the use of enum instead of
define the usual macro C-preprocessor define detection will not work. This is
done on purpose to discourage userspace from detecting features via header file
defines.).