// SPDX-License-Identifier: GPL-2.0
/* Refer to samples/bpf/tcp_bpf.readme for the instructions on
 * how to run this sample program.
 */
#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>
#include <bpf/bpf_endian.h>

#define INTERVAL                        1000000000ULL

int _version SEC("version") = 1;
char _license[] SEC("license") = "GPL";

struct {
        __u32 type;
        __u32 map_flags;
        int *key;
        __u64 *value;
} bpf_next_dump SEC(".maps") = {
        .type = BPF_MAP_TYPE_SK_STORAGE,
        .map_flags = BPF_F_NO_PREALLOC,
};

SEC("sockops")
int _sockops(struct bpf_sock_ops *ctx)
{
        struct bpf_tcp_sock *tcp_sk;
        struct bpf_sock *sk;
        __u64 *next_dump;
        __u64 now;

        switch (ctx->op) {
        case BPF_SOCK_OPS_TCP_CONNECT_CB:
                bpf_sock_ops_cb_flags_set(ctx, BPF_SOCK_OPS_RTT_CB_FLAG);
                return 1;
        case BPF_SOCK_OPS_RTT_CB:
                break;
        default:
                return 1;
        }

        sk = ctx->sk;
        if (!sk)
                return 1;

        next_dump = bpf_sk_storage_get(&bpf_next_dump, sk, 0,
                                       BPF_SK_STORAGE_GET_F_CREATE);
        if (!next_dump)
                return 1;

        now = bpf_ktime_get_ns();
        if (now < *next_dump)
                return 1;

        tcp_sk = bpf_tcp_sock(sk);
        if (!tcp_sk)
                return 1;

        *next_dump = now + INTERVAL;

        bpf_printk("dsack_dups=%u delivered=%u\n",
                   tcp_sk->dsack_dups, tcp_sk->delivered);
        bpf_printk("delivered_ce=%u icsk_retransmits=%u\n",
                   tcp_sk->delivered_ce, tcp_sk->icsk_retransmits);

        return 1;
}