// SPDX-License-Identifier: GPL-2.0
#include <stddef.h>
#include <string.h>
#include <netinet/in.h>
#include <linux/bpf.h>
#include <linux/if_ether.h>
#include <linux/if_packet.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/tcp.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_endian.h>
#include "test_tcpnotify.h"

struct {
        __uint(type, BPF_MAP_TYPE_ARRAY);
        __uint(max_entries, 4);
        __type(key, __u32);
        __type(value, struct tcpnotify_globals);
} global_map SEC(".maps");

struct {
        __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
        __type(key, int);
        __type(value, __u32);
} perf_event_map SEC(".maps");

SEC("sockops")
int bpf_testcb(struct bpf_sock_ops *skops)
{
        int rv = -1;
        int op;

        op = (int) skops->op;

        if (bpf_ntohl(skops->remote_port) != TESTPORT) {
                skops->reply = -1;
                return 0;
        }

        switch (op) {
        case BPF_SOCK_OPS_TIMEOUT_INIT:
        case BPF_SOCK_OPS_RWND_INIT:
        case BPF_SOCK_OPS_NEEDS_ECN:
        case BPF_SOCK_OPS_BASE_RTT:
        case BPF_SOCK_OPS_RTO_CB:
                rv = 1;
                break;

        case BPF_SOCK_OPS_TCP_CONNECT_CB:
        case BPF_SOCK_OPS_TCP_LISTEN_CB:
        case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB:
        case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB:
                bpf_sock_ops_cb_flags_set(skops, (BPF_SOCK_OPS_RETRANS_CB_FLAG|
                                          BPF_SOCK_OPS_RTO_CB_FLAG));
                rv = 1;
                break;
        case BPF_SOCK_OPS_RETRANS_CB: {
                        __u32 key = 0;
                        struct tcpnotify_globals g, *gp;
                        struct tcp_notifier msg = {
                                .type = 0xde,
                                .subtype = 0xad,
                                .source = 0xbe,
                                .hash = 0xef,
                        };

                        rv = 1;

                        /* Update results */
                        gp = bpf_map_lookup_elem(&global_map, &key);
                        if (!gp)
                                break;
                        g = *gp;
                        g.total_retrans = skops->total_retrans;
                        g.ncalls++;
                        bpf_map_update_elem(&global_map, &key, &g,
                                            BPF_ANY);
                        bpf_perf_event_output(skops, &perf_event_map,
                                              BPF_F_CURRENT_CPU,
                                              &msg, sizeof(msg));
                }
                break;
        default:
                rv = -1;
        }
        skops->reply = rv;
        return 1;
}
char _license[] SEC("license") = "GPL";