// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE
#include <test_progs.h>
#include "cgroup_helpers.h"
#include "network_helpers.h"
#include "tcp_rtt.skel.h"

struct tcp_rtt_storage {
        __u32 invoked;
        __u32 dsack_dups;
        __u32 delivered;
        __u32 delivered_ce;
        __u32 icsk_retransmits;

        __u32 mrtt_us;  /* args[0] */
        __u32 srtt;     /* args[1] */
};

static void send_byte(int fd)
{
        char b = 0x55;

        ASSERT_EQ(write(fd, &b, sizeof(b)), 1, "send single byte");
}

static int wait_for_ack(int fd, int retries)
{
        struct tcp_info info;
        socklen_t optlen;
        int i, err;

        for (i = 0; i < retries; i++) {
                optlen = sizeof(info);
                err = getsockopt(fd, SOL_TCP, TCP_INFO, &info, &optlen);
                if (err < 0) {
                        log_err("Failed to lookup TCP stats");
                        return err;
                }

                if (info.tcpi_unacked == 0)
                        return 0;

                usleep(10);
        }

        log_err("Did not receive ACK");
        return -1;
}

static int verify_sk(int map_fd, int client_fd, const char *msg, __u32 invoked,
                     __u32 dsack_dups, __u32 delivered, __u32 delivered_ce,
                     __u32 icsk_retransmits)
{
        int err = 0;
        struct tcp_rtt_storage val;

        if (!ASSERT_GE(bpf_map_lookup_elem(map_fd, &client_fd, &val), 0, "read socket storage"))
                return -1;

        if (val.invoked != invoked) {
                log_err("%s: unexpected bpf_tcp_sock.invoked %d != %d",
                        msg, val.invoked, invoked);
                err++;
        }

        if (val.dsack_dups != dsack_dups) {
                log_err("%s: unexpected bpf_tcp_sock.dsack_dups %d != %d",
                        msg, val.dsack_dups, dsack_dups);
                err++;
        }

        if (val.delivered != delivered) {
                log_err("%s: unexpected bpf_tcp_sock.delivered %d != %d",
                        msg, val.delivered, delivered);
                err++;
        }

        if (val.delivered_ce != delivered_ce) {
                log_err("%s: unexpected bpf_tcp_sock.delivered_ce %d != %d",
                        msg, val.delivered_ce, delivered_ce);
                err++;
        }

        if (val.icsk_retransmits != icsk_retransmits) {
                log_err("%s: unexpected bpf_tcp_sock.icsk_retransmits %d != %d",
                        msg, val.icsk_retransmits, icsk_retransmits);
                err++;
        }

        /* Precise values of mrtt and srtt are unavailable, just make sure they are nonzero */
        if (val.mrtt_us == 0) {
                log_err("%s: unexpected bpf_tcp_sock.args[0] (mrtt_us) %u == 0", msg, val.mrtt_us);
                err++;
        }

        if (val.srtt == 0) {
                log_err("%s: unexpected bpf_tcp_sock.args[1] (srtt) %u == 0", msg, val.srtt);
                err++;
        }

        return err;
}


static int run_test(int cgroup_fd, int server_fd)
{
        struct tcp_rtt *skel;
        int client_fd;
        int prog_fd;
        int map_fd;
        int err;

        skel = tcp_rtt__open_and_load();
        if (!ASSERT_OK_PTR(skel, "skel_open_load"))
                return -1;

        map_fd = bpf_map__fd(skel->maps.socket_storage_map);
        prog_fd = bpf_program__fd(skel->progs._sockops);

        err = bpf_prog_attach(prog_fd, cgroup_fd, BPF_CGROUP_SOCK_OPS, 0);
        if (err) {
                log_err("Failed to attach BPF program");
                goto close_bpf_object;
        }

        client_fd = connect_to_fd(server_fd, 0);
        if (client_fd < 0) {
                err = -1;
                goto close_bpf_object;
        }

        err += verify_sk(map_fd, client_fd, "syn-ack",
                         /*invoked=*/1,
                         /*dsack_dups=*/0,
                         /*delivered=*/1,
                         /*delivered_ce=*/0,
                         /*icsk_retransmits=*/0);

        send_byte(client_fd);
        if (wait_for_ack(client_fd, 100) < 0) {
                err = -1;
                goto close_client_fd;
        }


        err += verify_sk(map_fd, client_fd, "first payload byte",
                         /*invoked=*/2,
                         /*dsack_dups=*/0,
                         /*delivered=*/2,
                         /*delivered_ce=*/0,
                         /*icsk_retransmits=*/0);

close_client_fd:
        close(client_fd);

close_bpf_object:
        tcp_rtt__destroy(skel);
        return err;
}

void test_tcp_rtt(void)
{
        int server_fd, cgroup_fd;

        cgroup_fd = test__join_cgroup("/tcp_rtt");
        if (!ASSERT_GE(cgroup_fd, 0, "join_cgroup /tcp_rtt"))
                return;

        server_fd = start_server(AF_INET, SOCK_STREAM, NULL, 0, 0);
        if (!ASSERT_GE(server_fd, 0, "start_server"))
                goto close_cgroup_fd;

        ASSERT_OK(run_test(cgroup_fd, server_fd), "run_test");

        close(server_fd);

close_cgroup_fd:
        close(cgroup_fd);
}