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// SPDX-License-Identifier: GPL-2.0
#include <vmlinux.h>
#include <bpf/bpf_helpers.h>
#define ETH_ALEN 6
#define HDR_SZ (sizeof(struct ethhdr) + sizeof(struct ipv6hdr) + sizeof(struct udphdr))
const volatile int ifindex_out;
const volatile int ifindex_in;
const volatile __u8 expect_dst[ETH_ALEN];
volatile int pkts_seen_xdp = 0;
volatile int pkts_seen_zero = 0;
volatile int pkts_seen_tc = 0;
volatile int retcode = XDP_REDIRECT;
SEC("xdp")
int xdp_redirect(struct xdp_md *xdp)
{
__u32 *metadata = (void *)(long)xdp->data_meta;
void *data_end = (void *)(long)xdp->data_end;
void *data = (void *)(long)xdp->data;
__u8 *payload = data + HDR_SZ;
int ret = retcode;
if (payload + 1 > data_end)
return XDP_ABORTED;
if (xdp->ingress_ifindex != ifindex_in)
return XDP_ABORTED;
if (metadata + 1 > data)
return XDP_ABORTED;
if (*metadata != 0x42)
return XDP_ABORTED;
if (*payload == 0) {
*payload = 0x42;
pkts_seen_zero++;
}
if (bpf_xdp_adjust_meta(xdp, 4))
return XDP_ABORTED;
if (retcode > XDP_PASS)
retcode--;
if (ret == XDP_REDIRECT)
return bpf_redirect(ifindex_out, 0);
return ret;
}
static bool check_pkt(void *data, void *data_end)
{
struct ipv6hdr *iph = data + sizeof(struct ethhdr);
__u8 *payload = data + HDR_SZ;
if (payload + 1 > data_end)
return false;
if (iph->nexthdr != IPPROTO_UDP || *payload != 0x42)
return false;
/* reset the payload so the same packet doesn't get counted twice when
* it cycles back through the kernel path and out the dst veth
*/
*payload = 0;
return true;
}
SEC("xdp")
int xdp_count_pkts(struct xdp_md *xdp)
{
void *data = (void *)(long)xdp->data;
void *data_end = (void *)(long)xdp->data_end;
if (check_pkt(data, data_end))
pkts_seen_xdp++;
/* Return XDP_DROP to make sure the data page is recycled, like when it
* exits a physical NIC. Recycled pages will be counted in the
* pkts_seen_zero counter above.
*/
return XDP_DROP;
}
SEC("tc")
int tc_count_pkts(struct __sk_buff *skb)
{
void *data = (void *)(long)skb->data;
void *data_end = (void *)(long)skb->data_end;
if (check_pkt(data, data_end))
pkts_seen_tc++;
return 0;
}
char _license[] SEC("license") = "GPL";
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