pyroute2 + SRv6 example

bpf.c

#include <linux/bpf.h>

int pass(struct __sk_buff *skb) {
    return BPF_OK; // packet continues
    // return BPF_DROP; // packet drops
}

example.py

from bcc import BPF
from pyroute2 import IPRoute
from time import sleep
import sys, signal

b = BPF(src_file="bpf.c")
fn = b.load_func("pass", 19)
# 19 means BPF_PROG_TYPE_LWT_SEG6LOCAL
# https://github.com/torvalds/linux/blob/3cb12d27ff655e57e8efe3486dca2a22f4e30578/include/uapi/linux/bpf.h#L190

ipr = IPRoute()
idx = ipr.link_lookup(ifname="eth0")[0] # interface to attach
sid = 'fd00::1/128'

encap = {'type':'seg6local', 'action':'End.BPF', 'bpf':{'fd':fn.fd, 'name':fn.name}}
ipr.route("add", dst=sid, oif=idx, encap=encap)

print(f"Attached func {fn.name} to {sid}")

def remove_rt(sig, fr):
    ipr.route("del", dst=sid, oif=idx)
    print(f"Detached func {fn.name} from {sid}")
    sys.exit(0)


signal.signal(signal.SIGTERM, remove_rt)
signal.signal(signal.SIGINT, remove_rt)

while True:
    sleep(0.01)