/* Copyright (c) 2016 PLUMgrid
   *
   * 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.
   */
  #define KBUILD_MODNAME "foo"
  #include <uapi/linux/bpf.h>
  #include <linux/in.h>
  #include <linux/if_ether.h>
  #include <linux/if_packet.h>
  #include <linux/if_vlan.h>
  #include <linux/ip.h>
  #include <linux/ipv6.h>
  #include "bpf_helpers.h"

  struct bpf_map_def SEC("maps") rxcnt = {

  	.type = BPF_MAP_TYPE_PERCPU_ARRAY,
  	.key_size = sizeof(u32),
  	.value_size = sizeof(long),
  	.max_entries = 256,
  };
  
  static int parse_ipv4(void *data, u64 nh_off, void *data_end)
  {
  	struct iphdr *iph = data + nh_off;
  
  	if (iph + 1 > data_end)
  		return 0;
  	return iph->protocol;
  }
  
  static int parse_ipv6(void *data, u64 nh_off, void *data_end)
  {
  	struct ipv6hdr *ip6h = data + nh_off;
  
  	if (ip6h + 1 > data_end)
  		return 0;
  	return ip6h->nexthdr;
  }
  
  SEC("xdp1")
  int xdp_prog1(struct xdp_md *ctx)
  {
  	void *data_end = (void *)(long)ctx->data_end;
  	void *data = (void *)(long)ctx->data;
  	struct ethhdr *eth = data;
  	int rc = XDP_DROP;
  	long *value;
  	u16 h_proto;
  	u64 nh_off;

  	u32 ipproto;

  
  	nh_off = sizeof(*eth);
  	if (data + nh_off > data_end)
  		return rc;
  
  	h_proto = eth->h_proto;
  
  	if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
  		struct vlan_hdr *vhdr;
  
  		vhdr = data + nh_off;
  		nh_off += sizeof(struct vlan_hdr);
  		if (data + nh_off > data_end)
  			return rc;
  		h_proto = vhdr->h_vlan_encapsulated_proto;
  	}
  	if (h_proto == htons(ETH_P_8021Q) || h_proto == htons(ETH_P_8021AD)) {
  		struct vlan_hdr *vhdr;
  
  		vhdr = data + nh_off;
  		nh_off += sizeof(struct vlan_hdr);
  		if (data + nh_off > data_end)
  			return rc;
  		h_proto = vhdr->h_vlan_encapsulated_proto;
  	}
  
  	if (h_proto == htons(ETH_P_IP))

  		ipproto = parse_ipv4(data, nh_off, data_end);

  	else if (h_proto == htons(ETH_P_IPV6))

  		ipproto = parse_ipv6(data, nh_off, data_end);

  	else

  		ipproto = 0;

  	value = bpf_map_lookup_elem(&rxcnt, &ipproto);

  	if (value)
  		*value += 1;
  
  	return rc;
  }
  
  char _license[] SEC("license") = "GPL";