1 /* SPDX-License-Identifier: GPL-2.0 */
2 // Copyright (c) 2018 Politecnico di Torino
3 #include <stddef.h>
4 #include <string.h>
5 #include <linux/bpf.h>
6 #include <linux/if_ether.h>
7 #include <linux/ip.h>
8 #include <linux/pkt_cls.h>
9 #include <bpf/bpf_helpers.h>
10
11 struct {
12 __uint(type, MAP_TYPE);
13 __uint(max_entries, 32);
14 __uint(map_flags, 0);
15 __uint(key_size, 0);
16 __uint(value_size, sizeof(__u32));
17 } map_in SEC(".maps");
18
19 struct {
20 __uint(type, MAP_TYPE);
21 __uint(max_entries, 32);
22 __uint(map_flags, 0);
23 __uint(key_size, 0);
24 __uint(value_size, sizeof(__u32));
25 } map_out SEC(".maps");
26
27 SEC("tc")
28 int _test(struct __sk_buff *skb)
29 {
30 void *data_end = (void *)(long)skb->data_end;
31 void *data = (void *)(long)skb->data;
32 struct ethhdr *eth = (struct ethhdr *)(data);
33 __u32 value;
34 int err;
35
36 if (eth + 1 > data_end)
37 return TC_ACT_SHOT;
38
39 struct iphdr *iph = (struct iphdr *)(eth + 1);
40
41 if (iph + 1 > data_end)
42 return TC_ACT_SHOT;
43
44 err = bpf_map_pop_elem(&map_in, &value);
45 if (err)
46 return TC_ACT_SHOT;
47
48 iph->daddr = value;
49
50 err = bpf_map_push_elem(&map_out, &iph->saddr, 0);
51 if (err)
52 return TC_ACT_SHOT;
53
54 return TC_ACT_OK;
55 }
56
57 char _license[] SEC("license") = "GPL";
58
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