/* Copyright (c) 2016 John Fastabend <john.r.fastabend@intel.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#define KBUILD_MODNAME "foo"
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#include <uapi/linux/bpf.h>
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#include <linux/in.h>
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#include <linux/if_ether.h>
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#include <linux/if_packet.h>
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#include <linux/if_vlan.h>
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#include <linux/ip.h>
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#include <linux/ipv6.h>
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#include <bpf/bpf_helpers.h>
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struct {
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__uint(type, BPF_MAP_TYPE_ARRAY);
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__type(key, int);
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__type(value, int);
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__uint(max_entries, 1);
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} tx_port SEC(".maps");
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/* Count RX packets, as XDP bpf_prog doesn't get direct TX-success
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* feedback. Redirect TX errors can be caught via a tracepoint.
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*/
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struct {
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__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
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__type(key, u32);
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__type(value, long);
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__uint(max_entries, 1);
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} rxcnt SEC(".maps");
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static void swap_src_dst_mac(void *data)
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{
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unsigned short *p = data;
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unsigned short dst[3];
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dst[0] = p[0];
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dst[1] = p[1];
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dst[2] = p[2];
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p[0] = p[3];
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p[1] = p[4];
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p[2] = p[5];
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p[3] = dst[0];
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p[4] = dst[1];
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p[5] = dst[2];
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}
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SEC("xdp_redirect")
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int xdp_redirect_prog(struct xdp_md *ctx)
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{
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void *data_end = (void *)(long)ctx->data_end;
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void *data = (void *)(long)ctx->data;
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struct ethhdr *eth = data;
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int rc = XDP_DROP;
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int *ifindex, port = 0;
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long *value;
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u32 key = 0;
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u64 nh_off;
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nh_off = sizeof(*eth);
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if (data + nh_off > data_end)
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return rc;
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ifindex = bpf_map_lookup_elem(&tx_port, &port);
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if (!ifindex)
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return rc;
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value = bpf_map_lookup_elem(&rxcnt, &key);
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if (value)
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*value += 1;
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swap_src_dst_mac(data);
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return bpf_redirect(*ifindex, 0);
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}
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/* Redirect require an XDP bpf_prog loaded on the TX device */
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SEC("xdp_redirect_dummy")
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int xdp_redirect_dummy_prog(struct xdp_md *ctx)
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{
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return XDP_PASS;
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}
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char _license[] SEC("license") = "GPL";
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