mirror of
https://github.com/xdp-project/bpf-examples.git
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583f7a213f
Makes sure the ethertype is set correctly depending on the type of encapsulation. Fixes #2. Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
72 lines
1.5 KiB
C
72 lines
1.5 KiB
C
#define NEXTHDR_IPV6 41
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#ifdef IPV6
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static void encap_ipv6(volatile void *data, volatile void *data_end)
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{
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volatile struct ipv6hdr *ip6h;
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volatile struct ethhdr *eth;
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size_t len;
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struct ipv6hdr encap_hdr = {
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.version = 6,
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.nexthdr = NEXTHDR_IPV6,
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.hop_limit = 16,
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.saddr = { .s6_addr = { 0xfc, 0x00, 0xde, 0xad, 0xca, 0xfe,
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0x00, 0x02, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x02 } },
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.daddr = { .s6_addr = { 0xfc, 0x00, 0xde, 0xad, 0xca, 0xfe,
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0x00, 0x02, 0x00, 0x00, 0x00, 0x00,
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0x00, 0x00, 0x00, 0x01 } },
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};
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eth = data;
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ip6h = (void *)(eth +1);
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if (ip6h + 1 > data_end)
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return;
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eth->h_proto = bpf_htons(ETH_P_IPV6);
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*ip6h = encap_hdr;
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len = (data_end - data);
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ip6h->payload_len = bpf_htons(len - sizeof(struct ethhdr) - sizeof(*ip6h));
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}
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#else
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static __always_inline __u16 csum_fold_helper(__u32 csum)
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{
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__u32 sum;
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sum = (csum >> 16) + (csum & 0xffff);
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sum += (sum >> 16);
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return ~sum;
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}
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static void encap_ipv4(volatile void *data, volatile void *data_end)
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{
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volatile struct ethhdr *eth;
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volatile struct iphdr *iph;
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size_t len;
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struct iphdr encap_hdr = {
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.version = 4,
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.ihl = 5,
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.protocol = NEXTHDR_IPV6,
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.ttl = 16,
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.saddr = bpf_htonl(0x0a0b0202),
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.daddr = bpf_htonl(0x0a0b0201),
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};
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eth = data;
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iph = (void *)(eth +1);
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if (iph + 1 > data_end)
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return;
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eth->h_proto = bpf_htons(ETH_P_IP);
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*iph = encap_hdr;
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len = (data_end - data);
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iph->tot_len = bpf_htons(len - sizeof(struct ethhdr));
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iph->check = csum_fold_helper(bpf_csum_diff((__be32 *)iph, 0, (__be32 *)iph, sizeof(*iph), 0));
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}
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#endif
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