name : xdp_redirect_map.py #!/usr/bin/python # # xdp_redirect_map.py Redirect the incoming packet to another interface # with the helper: bpf_redirect_map() # # Copyright (c) 2018 Gary Lin # Licensed under the Apache License, Version 2.0 (the "License") from bcc import BPF import pyroute2 import time import sys import ctypes as ct flags = 0 def usage(): print("Usage: {0} <in ifdev> <out ifdev>".format(sys.argv[0])) print("e.g.: {0} eth0 eth1\n".format(sys.argv[0])) exit(1) if len(sys.argv) != 3: usage() in_if = sys.argv[1] out_if = sys.argv[2] ip = pyroute2.IPRoute() out_idx = ip.link_lookup(ifname=out_if)[0] # load BPF program b = BPF(text = """ #include <uapi/linux/bpf.h> #include <linux/in.h> #include <linux/if_ether.h> BPF_DEVMAP(tx_port, 1); BPF_PERCPU_ARRAY(rxcnt, long, 1); static inline void swap_src_dst_mac(void *data) { unsigned short *p = data; unsigned short dst[3]; dst[0] = p[0]; dst[1] = p[1]; dst[2] = p[2]; p[0] = p[3]; p[1] = p[4]; p[2] = p[5]; p[3] = dst[0]; p[4] = dst[1]; p[5] = dst[2]; } int xdp_redirect_map(struct xdp_md *ctx) { void* data_end = (void*)(long)ctx->data_end; void* data = (void*)(long)ctx->data; struct ethhdr *eth = data; uint32_t key = 0; long *value; uint64_t nh_off; nh_off = sizeof(*eth); if (data + nh_off > data_end) return XDP_DROP; value = rxcnt.lookup(&key); if (value) *value += 1; swap_src_dst_mac(data); return tx_port.redirect_map(0, 0); } int xdp_dummy(struct xdp_md *ctx) { return XDP_PASS; } """, cflags=["-w"]) tx_port = b.get_table("tx_port") tx_port[0] = ct.c_int(out_idx) in_fn = b.load_func("xdp_redirect_map", BPF.XDP) out_fn = b.load_func("xdp_dummy", BPF.XDP) b.attach_xdp(in_if, in_fn, flags) b.attach_xdp(out_if, out_fn, flags) rxcnt = b.get_table("rxcnt") prev = 0 print("Printing redirected packets, hit CTRL+C to stop") while 1: try: val = rxcnt.sum(0).value if val: delta = val - prev prev = val print("{} pkt/s".format(delta)) time.sleep(1) except KeyboardInterrupt: print("Removing filter from device") break b.remove_xdp(in_if, flags) b.remove_xdp(out_if, flags)