// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2020 Jesper Dangaard Brouer */

#include <linux/if_link.h> /* before test_progs.h, avoid bpf_util.h redefines */
#include <test_progs.h>
#include "test_check_mtu.skel.h"
#include "network_helpers.h"

#include <stdlib.h>
#include <inttypes.h>

#define IFINDEX_LO 1

static __u32 duration; /* Hint: needed for CHECK macro */

static int read_mtu_device_lo(void)
{
        const char *filename = "/sys/class/net/lo/mtu";
        char buf[11] = {};
        int value, n, fd;

        fd = open(filename, 0, O_RDONLY);
        if (fd == -1)
                return -1;

        n = read(fd, buf, sizeof(buf));
        close(fd);

        if (n == -1)
                return -2;

        value = strtoimax(buf, NULL, 10);
        if (errno == ERANGE)
                return -3;

        return value;
}

static void test_check_mtu_xdp_attach(void)
{
        struct bpf_link_info link_info;
        __u32 link_info_len = sizeof(link_info);
        struct test_check_mtu *skel;
        struct bpf_program *prog;
        struct bpf_link *link;
        int err = 0;
        int fd;

        skel = test_check_mtu__open_and_load();
        if (CHECK(!skel, "open and load skel", "failed"))
                return; /* Exit if e.g. helper unknown to kernel */

        prog = skel->progs.xdp_use_helper_basic;

        link = bpf_program__attach_xdp(prog, IFINDEX_LO);
        if (!ASSERT_OK_PTR(link, "link_attach"))
                goto out;
        skel->links.xdp_use_helper_basic = link;

        memset(&link_info, 0, sizeof(link_info));
        fd = bpf_link__fd(link);
        err = bpf_link_get_info_by_fd(fd, &link_info, &link_info_len);
        if (CHECK(err, "link_info", "failed: %d\n", err))
                goto out;

        CHECK(link_info.type != BPF_LINK_TYPE_XDP, "link_type",
              "got %u != exp %u\n", link_info.type, BPF_LINK_TYPE_XDP);
        CHECK(link_info.xdp.ifindex != IFINDEX_LO, "link_ifindex",
              "got %u != exp %u\n", link_info.xdp.ifindex, IFINDEX_LO);

        err = bpf_link__detach(link);
        CHECK(err, "link_detach", "failed %d\n", err);

out:
        test_check_mtu__destroy(skel);
}

static void test_check_mtu_run_xdp(struct test_check_mtu *skel,
                                   struct bpf_program *prog,
                                   __u32 mtu_expect)
{
        int retval_expect = XDP_PASS;
        __u32 mtu_result = 0;
        char buf[256] = {};
        int err, prog_fd = bpf_program__fd(prog);
        LIBBPF_OPTS(bpf_test_run_opts, topts,
                .repeat = 1,
                .data_in = &pkt_v4,
                .data_size_in = sizeof(pkt_v4),
                .data_out = buf,
                .data_size_out = sizeof(buf),
        );

        err = bpf_prog_test_run_opts(prog_fd, &topts);
        ASSERT_OK(err, "test_run");
        ASSERT_EQ(topts.retval, retval_expect, "retval");

        /* Extract MTU that BPF-prog got */
        mtu_result = skel->bss->global_bpf_mtu_xdp;
        ASSERT_EQ(mtu_result, mtu_expect, "MTU-compare-user");
}


static void test_check_mtu_xdp(__u32 mtu, __u32 ifindex)
{
        struct test_check_mtu *skel;
        int err;

        skel = test_check_mtu__open();
        if (CHECK(!skel, "skel_open", "failed"))
                return;

        /* Update "constants" in BPF-prog *BEFORE* libbpf load */
        skel->rodata->GLOBAL_USER_MTU = mtu;
        skel->rodata->GLOBAL_USER_IFINDEX = ifindex;

        err = test_check_mtu__load(skel);
        if (CHECK(err, "skel_load", "failed: %d\n", err))
                goto cleanup;

        test_check_mtu_run_xdp(skel, skel->progs.xdp_use_helper, mtu);
        test_check_mtu_run_xdp(skel, skel->progs.xdp_exceed_mtu, mtu);
        test_check_mtu_run_xdp(skel, skel->progs.xdp_minus_delta, mtu);
        test_check_mtu_run_xdp(skel, skel->progs.xdp_input_len, mtu);
        test_check_mtu_run_xdp(skel, skel->progs.xdp_input_len_exceed, mtu);

cleanup:
        test_check_mtu__destroy(skel);
}

static void test_check_mtu_run_tc(struct test_check_mtu *skel,
                                  struct bpf_program *prog,
                                  __u32 mtu_expect)
{
        int retval_expect = BPF_OK;
        __u32 mtu_result = 0;
        char buf[256] = {};
        int err, prog_fd = bpf_program__fd(prog);
        LIBBPF_OPTS(bpf_test_run_opts, topts,
                .data_in = &pkt_v4,
                .data_size_in = sizeof(pkt_v4),
                .data_out = buf,
                .data_size_out = sizeof(buf),
                .repeat = 1,
        );

        err = bpf_prog_test_run_opts(prog_fd, &topts);
        ASSERT_OK(err, "test_run");
        ASSERT_EQ(topts.retval, retval_expect, "retval");

        /* Extract MTU that BPF-prog got */
        mtu_result = skel->bss->global_bpf_mtu_tc;
        ASSERT_EQ(mtu_result, mtu_expect, "MTU-compare-user");
}

static void test_chk_segs_flag(struct test_check_mtu *skel, __u32 mtu)
{
        int err, prog_fd = bpf_program__fd(skel->progs.tc_chk_segs_flag);
        struct __sk_buff skb = {
                .gso_size = 10,
        };
        LIBBPF_OPTS(bpf_test_run_opts, topts,
                    .data_in = &pkt_v4,
                    .data_size_in = sizeof(pkt_v4),
                    .ctx_in = &skb,
                    .ctx_size_in = sizeof(skb),
        );

        /* Lower the mtu to test the BPF_MTU_CHK_SEGS */
        SYS_NOFAIL("ip link set dev lo mtu 10");
        err = bpf_prog_test_run_opts(prog_fd, &topts);
        SYS_NOFAIL("ip link set dev lo mtu %u", mtu);
        ASSERT_OK(err, "test_run");
        ASSERT_EQ(topts.retval, BPF_OK, "retval");
}

static void test_check_mtu_tc(__u32 mtu, __u32 ifindex)
{
        struct test_check_mtu *skel;
        int err;

        skel = test_check_mtu__open();
        if (CHECK(!skel, "skel_open", "failed"))
                return;

        /* Update "constants" in BPF-prog *BEFORE* libbpf load */
        skel->rodata->GLOBAL_USER_MTU = mtu;
        skel->rodata->GLOBAL_USER_IFINDEX = ifindex;

        err = test_check_mtu__load(skel);
        if (CHECK(err, "skel_load", "failed: %d\n", err))
                goto cleanup;

        test_check_mtu_run_tc(skel, skel->progs.tc_use_helper, mtu);
        test_check_mtu_run_tc(skel, skel->progs.tc_exceed_mtu, mtu);
        test_check_mtu_run_tc(skel, skel->progs.tc_exceed_mtu_da, mtu);
        test_check_mtu_run_tc(skel, skel->progs.tc_minus_delta, mtu);
        test_check_mtu_run_tc(skel, skel->progs.tc_input_len, mtu);
        test_check_mtu_run_tc(skel, skel->progs.tc_input_len_exceed, mtu);
        test_chk_segs_flag(skel, mtu);
cleanup:
        test_check_mtu__destroy(skel);
}

void test_ns_check_mtu(void)
{
        int mtu_lo;

        if (test__start_subtest("bpf_check_mtu XDP-attach"))
                test_check_mtu_xdp_attach();

        mtu_lo = read_mtu_device_lo();
        if (CHECK(mtu_lo < 0, "reading MTU value", "failed (err:%d)", mtu_lo))
                return;

        if (test__start_subtest("bpf_check_mtu XDP-run"))
                test_check_mtu_xdp(mtu_lo, 0);

        if (test__start_subtest("bpf_check_mtu XDP-run ifindex-lookup"))
                test_check_mtu_xdp(mtu_lo, IFINDEX_LO);

        if (test__start_subtest("bpf_check_mtu TC-run"))
                test_check_mtu_tc(mtu_lo, 0);

        if (test__start_subtest("bpf_check_mtu TC-run ifindex-lookup"))
                test_check_mtu_tc(mtu_lo, IFINDEX_LO);
}