cgroup_skb.c

// +build ignore

#include "common.h"

char __license[] SEC("license") = "Dual MIT/GPL";

struct bpf_map_def SEC("maps") pkt_count = {
	.type        = BPF_MAP_TYPE_ARRAY,
	.key_size    = sizeof(u32),
	.value_size  = sizeof(u64),
	.max_entries = 1,
};

SEC("cgroup_skb/egress")
int count_egress_packets(struct __sk_buff *skb) {
	u32 key      = 0;
	u64 init_val = 1;

	u64 *count = bpf_map_lookup_elem(&pkt_count, &key);
	if (!count) {
		bpf_map_update_elem(&pkt_count, &key, &init_val, BPF_ANY);
		return 1;
	}
	__sync_fetch_and_add(count, 1);

	return 1;
}