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/* Copyright (c) 2016 Facebook
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*/
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/in.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <uapi/linux/bpf.h>
#include "bpf_helpers.h"
#define DEFAULT_PKTGEN_UDP_PORT 9
#define IP_MF 0x2000
#define IP_OFFSET 0x1FFF
static inline int ip_is_fragment(struct __sk_buff *ctx, __u64 nhoff)
{
return load_half(ctx, nhoff + offsetof(struct iphdr, frag_off))
& (IP_MF | IP_OFFSET);
}
SEC("ldabs")
int handle_ingress(struct __sk_buff *skb)
{
__u64 troff = ETH_HLEN + sizeof(struct iphdr);
if (load_half(skb, offsetof(struct ethhdr, h_proto)) != ETH_P_IP)
return 0;
if (load_byte(skb, ETH_HLEN + offsetof(struct iphdr, protocol)) != IPPROTO_UDP ||
load_byte(skb, ETH_HLEN) != 0x45)
return 0;
if (ip_is_fragment(skb, ETH_HLEN))
return 0;
if (load_half(skb, troff + offsetof(struct udphdr, dest)) == DEFAULT_PKTGEN_UDP_PORT)
return TC_ACT_SHOT;
return 0;
}
char _license[] SEC("license") = "GPL";
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