// SPDX-License-Identifier: GPL-2.0-only

#include <sys/socket.h>
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>

int invocations = 0, in_use = 0;

struct {
        __uint(type, BPF_MAP_TYPE_SK_STORAGE);
        __uint(map_flags, BPF_F_NO_PREALLOC);
        __type(key, int);
        __type(value, int);
} sk_map SEC(".maps");

SEC("cgroup/sock_create")
int sock(struct bpf_sock *ctx)
{
        int *sk_storage;

        if (ctx->type != SOCK_DGRAM)
                return 1;

        sk_storage = bpf_sk_storage_get(&sk_map, ctx, 0,
                                        BPF_SK_STORAGE_GET_F_CREATE);
        if (!sk_storage)
                return 0;
        *sk_storage = 0xdeadbeef;

        __sync_fetch_and_add(&invocations, 1);

        if (in_use > 0) {
                /* BPF_CGROUP_INET_SOCK_RELEASE is _not_ called
                 * when we return an error from the BPF
                 * program!
                 */
                return 0;
        }

        __sync_fetch_and_add(&in_use, 1);
        return 1;
}

SEC("cgroup/sock_release")
int sock_release(struct bpf_sock *ctx)
{
        int *sk_storage;

        if (ctx->type != SOCK_DGRAM)
                return 1;

        sk_storage = bpf_sk_storage_get(&sk_map, ctx, 0, 0);
        if (!sk_storage || *sk_storage != 0xdeadbeef)
                return 0;

        __sync_fetch_and_add(&invocations, 1);
        __sync_fetch_and_add(&in_use, -1);
        return 1;
}