// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
#include <test_progs.h>
#include "cgroup_helpers.h"
#include "cgroup_preorder.skel.h"

static int run_getsockopt_test(int cg_parent, int cg_child, int sock_fd, bool all_preorder)
{
        LIBBPF_OPTS(bpf_prog_attach_opts, opts);
        enum bpf_attach_type prog_c_atype, prog_c2_atype, prog_p_atype, prog_p2_atype;
        int prog_c_fd, prog_c2_fd, prog_p_fd, prog_p2_fd;
        struct cgroup_preorder *skel = NULL;
        struct bpf_program *prog;
        __u8 *result, buf;
        socklen_t optlen;
        int err = 0;

        skel = cgroup_preorder__open_and_load();
        if (!ASSERT_OK_PTR(skel, "cgroup_preorder__open_and_load"))
                return 0;

        buf = 0x00;
        err = setsockopt(sock_fd, SOL_IP, IP_TOS, &buf, 1);
        if (!ASSERT_OK(err, "setsockopt"))
                goto close_skel;

        opts.flags = BPF_F_ALLOW_MULTI;
        if (all_preorder)
                opts.flags |= BPF_F_PREORDER;
        prog = skel->progs.child;
        prog_c_fd = bpf_program__fd(prog);
        prog_c_atype = bpf_program__expected_attach_type(prog);
        err = bpf_prog_attach_opts(prog_c_fd, cg_child, prog_c_atype, &opts);
        if (!ASSERT_OK(err, "bpf_prog_attach_opts-child"))
                goto close_skel;

        opts.flags = BPF_F_ALLOW_MULTI | BPF_F_PREORDER;
        prog = skel->progs.child_2;
        prog_c2_fd = bpf_program__fd(prog);
        prog_c2_atype = bpf_program__expected_attach_type(prog);
        err = bpf_prog_attach_opts(prog_c2_fd, cg_child, prog_c2_atype, &opts);
        if (!ASSERT_OK(err, "bpf_prog_attach_opts-child_2"))
                goto detach_child;

        optlen = 1;
        err = getsockopt(sock_fd, SOL_IP, IP_TOS, &buf, &optlen);
        if (!ASSERT_OK(err, "getsockopt"))
                goto detach_child_2;

        result = skel->bss->result;
        if (all_preorder)
                ASSERT_TRUE(result[0] == 1 && result[1] == 2, "child only");
        else
                ASSERT_TRUE(result[0] == 2 && result[1] == 1, "child only");

        skel->bss->idx = 0;
        memset(result, 0, 4);

        opts.flags = BPF_F_ALLOW_MULTI;
        if (all_preorder)
                opts.flags |= BPF_F_PREORDER;
        prog = skel->progs.parent;
        prog_p_fd = bpf_program__fd(prog);
        prog_p_atype = bpf_program__expected_attach_type(prog);
        err = bpf_prog_attach_opts(prog_p_fd, cg_parent, prog_p_atype, &opts);
        if (!ASSERT_OK(err, "bpf_prog_attach_opts-parent"))
                goto detach_child_2;

        opts.flags = BPF_F_ALLOW_MULTI | BPF_F_PREORDER;
        prog = skel->progs.parent_2;
        prog_p2_fd = bpf_program__fd(prog);
        prog_p2_atype = bpf_program__expected_attach_type(prog);
        err = bpf_prog_attach_opts(prog_p2_fd, cg_parent, prog_p2_atype, &opts);
        if (!ASSERT_OK(err, "bpf_prog_attach_opts-parent_2"))
                goto detach_parent;

        err = getsockopt(sock_fd, SOL_IP, IP_TOS, &buf, &optlen);
        if (!ASSERT_OK(err, "getsockopt"))
                goto detach_parent_2;

        if (all_preorder)
                ASSERT_TRUE(result[0] == 3 && result[1] == 4 && result[2] == 1 && result[3] == 2,
                            "parent and child");
        else
                ASSERT_TRUE(result[0] == 4 && result[1] == 2 && result[2] == 1 && result[3] == 3,
                            "parent and child");

detach_parent_2:
        ASSERT_OK(bpf_prog_detach2(prog_p2_fd, cg_parent, prog_p2_atype),
                  "bpf_prog_detach2-parent_2");
detach_parent:
        ASSERT_OK(bpf_prog_detach2(prog_p_fd, cg_parent, prog_p_atype),
                  "bpf_prog_detach2-parent");
detach_child_2:
        ASSERT_OK(bpf_prog_detach2(prog_c2_fd, cg_child, prog_c2_atype),
                  "bpf_prog_detach2-child_2");
detach_child:
        ASSERT_OK(bpf_prog_detach2(prog_c_fd, cg_child, prog_c_atype),
                  "bpf_prog_detach2-child");
close_skel:
        cgroup_preorder__destroy(skel);
        return err;
}

/*
 * Replacing a link's program (bpf_link_update) must target the correct slot in
 * the effective array even when a BPF_F_PREORDER program is attached to the
 * same cgroup. All programs here are attached to a single cgroup; "parent" is
 * reused only as a third distinct program.
 *
 * Attach child(1) normally and child_2(2) with BPF_F_PREORDER, so the effective
 * order is [2, 1]. Then replace child(1)'s program with parent(3): only the
 * non-preorder slot changes, giving [2, 3].
 */
static int run_link_replace_test(int cgroup_fd, int sock_fd)
{
        LIBBPF_OPTS(bpf_link_create_opts, create_opts);
        int err = 0, normal_link = -1, preorder_link = -1;
        struct cgroup_preorder *skel = NULL;
        enum bpf_attach_type atype;
        __u8 *result, buf = 0x00;
        socklen_t optlen = 1;

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

        err = setsockopt(sock_fd, SOL_IP, IP_TOS, &buf, 1);
        if (!ASSERT_OK(err, "setsockopt"))
                goto close_skel;

        atype = bpf_program__expected_attach_type(skel->progs.child);

        create_opts.flags = 0;
        normal_link = bpf_link_create(bpf_program__fd(skel->progs.child),
                                      cgroup_fd, atype, &create_opts);
        if (!ASSERT_GE(normal_link, 0, "create_normal_link")) {
                err = normal_link;
                goto close_skel;
        }

        create_opts.flags = BPF_F_PREORDER;
        preorder_link = bpf_link_create(bpf_program__fd(skel->progs.child_2),
                                        cgroup_fd, atype, &create_opts);
        if (!ASSERT_GE(preorder_link, 0, "create_preorder_link")) {
                err = preorder_link;
                goto close_links;
        }

        result = skel->bss->result;
        skel->bss->idx = 0;
        memset(result, 0, 4);

        err = getsockopt(sock_fd, SOL_IP, IP_TOS, &buf, &optlen);
        if (!ASSERT_OK(err, "getsockopt-before"))
                goto close_links;
        ASSERT_TRUE(result[0] == 2 && result[1] == 1, "order before update");

        /* Replace the normal link's program child(1) -> parent(3). */
        err = bpf_link_update(normal_link, bpf_program__fd(skel->progs.parent), NULL);
        if (!ASSERT_OK(err, "bpf_link_update"))
                goto close_links;

        skel->bss->idx = 0;
        memset(result, 0, 4);

        err = getsockopt(sock_fd, SOL_IP, IP_TOS, &buf, &optlen);
        if (!ASSERT_OK(err, "getsockopt-after"))
                goto close_links;
        ASSERT_TRUE(result[0] == 2 && result[1] == 3, "order after update");

close_links:
        if (preorder_link >= 0)
                close(preorder_link);
        close(normal_link);
close_skel:
        cgroup_preorder__destroy(skel);
        return err;
}

void test_cgroup_preorder(void)
{
        int cg_parent = -1, cg_child = -1, sock_fd = -1;

        cg_parent = test__join_cgroup("/parent");
        if (!ASSERT_GE(cg_parent, 0, "join_cgroup /parent"))
                goto out;

        cg_child = test__join_cgroup("/parent/child");
        if (!ASSERT_GE(cg_child, 0, "join_cgroup /parent/child"))
                goto out;

        sock_fd = socket(AF_INET, SOCK_STREAM, 0);
        if (!ASSERT_GE(sock_fd, 0, "socket"))
                goto out;

        ASSERT_OK(run_getsockopt_test(cg_parent, cg_child, sock_fd, false), "getsockopt_test_1");
        ASSERT_OK(run_getsockopt_test(cg_parent, cg_child, sock_fd, true), "getsockopt_test_2");
        ASSERT_OK(run_link_replace_test(cg_child, sock_fd), "link_replace_test");

out:
        close(sock_fd);
        close(cg_child);
        close(cg_parent);
}