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1// SPDX-License-Identifier: GPL-2.02#include <inttypes.h>3#include <linux/bpf.h>4#include <bpf/bpf_endian.h>5#include <bpf/bpf_helpers.h>6#include <linux/if_ether.h>7#include <linux/ip.h>8 9/* This function extracts the last byte of the daddr, and uses it10 * as output dev index.11 */12SEC("lwt_xmit")13int test_lwt_reroute(struct __sk_buff *skb)14{15 struct iphdr *iph = NULL;16 void *start = (void *)(long)skb->data;17 void *end = (void *)(long)skb->data_end;18 19 /* set mark at most once */20 if (skb->mark != 0)21 return BPF_OK;22 23 if (start + sizeof(*iph) > end)24 return BPF_DROP;25 26 iph = (struct iphdr *)start;27 skb->mark = bpf_ntohl(iph->daddr) & 0xff;28 29 /* do not reroute x.x.x.0 packets */30 if (skb->mark == 0)31 return BPF_OK;32 33 return BPF_LWT_REROUTE;34}35 36char _license[] SEC("license") = "GPL";37