/* SPDX-License-Identifier: GPL-2.0 */
/*
 * bpf_libbpf.c         BPF code relay on libbpf
 * Authors:             Hangbin Liu <haliu@redhat.com>
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <stdbool.h>
#include <stdint.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>

#include <libelf.h>
#include <gelf.h>

#include <bpf/libbpf.h>
#include <bpf/bpf.h>

#include "bpf_util.h"

static int verbose_print(enum libbpf_print_level level, const char *format, va_list args)
{
        return vfprintf(stderr, format, args);
}

static int silent_print(enum libbpf_print_level level, const char *format, va_list args)
{
        if (level > LIBBPF_WARN)
                return 0;

        /* Skip warning from bpf_object__init_user_maps() for legacy maps */
        if (strstr(format, "has unrecognized, non-zero options"))
                return 0;

        return vfprintf(stderr, format, args);
}

static const char *get_bpf_program__section_name(const struct bpf_program *prog)
{
#ifdef HAVE_LIBBPF_SECTION_NAME
        return bpf_program__section_name(prog);
#else
        return bpf_program__title(prog, false);
#endif
}

static int create_map(const char *name, struct bpf_elf_map *map,
                      __u32 ifindex, int inner_fd)
{
        struct bpf_create_map_attr map_attr = {};

        map_attr.name = name;
        map_attr.map_type = map->type;
        map_attr.map_flags = map->flags;
        map_attr.key_size = map->size_key;
        map_attr.value_size = map->size_value;
        map_attr.max_entries = map->max_elem;
        map_attr.map_ifindex = ifindex;
        map_attr.inner_map_fd = inner_fd;

        return bpf_create_map_xattr(&map_attr);
}

static int create_map_in_map(struct bpf_object *obj, struct bpf_map *map,
                             struct bpf_elf_map *elf_map, int inner_fd,
                             bool *reuse_pin_map)
{
        char pathname[PATH_MAX];
        const char *map_name;
        bool pin_map = false;
        int map_fd, ret = 0;

        map_name = bpf_map__name(map);

        if (iproute2_is_pin_map(map_name, pathname)) {
                pin_map = true;

                /* Check if there already has a pinned map */
                map_fd = bpf_obj_get(pathname);
                if (map_fd > 0) {
                        if (reuse_pin_map)
                                *reuse_pin_map = true;
                        close(map_fd);
                        return bpf_map__set_pin_path(map, pathname);
                }
        }

        map_fd = create_map(map_name, elf_map, bpf_map__ifindex(map), inner_fd);
        if (map_fd < 0) {
                fprintf(stderr, "create map %s failed\n", map_name);
                return map_fd;
        }

        ret = bpf_map__reuse_fd(map, map_fd);
        if (ret < 0) {
                fprintf(stderr, "map %s reuse fd failed\n", map_name);
                goto err_out;
        }

        if (pin_map) {
                ret = bpf_map__set_pin_path(map, pathname);
                if (ret < 0)
                        goto err_out;
        }

        return 0;
err_out:
        close(map_fd);
        return ret;
}

static int
handle_legacy_map_in_map(struct bpf_object *obj, struct bpf_map *inner_map,
                         const char *inner_map_name)
{
        int inner_fd, outer_fd, inner_idx, ret = 0;
        struct bpf_elf_map imap, omap;
        struct bpf_map *outer_map;
        /* What's the size limit of map name? */
        char outer_map_name[128];
        bool reuse_pin_map = false;

        /* Deal with map-in-map */
        if (iproute2_is_map_in_map(inner_map_name, &imap, &omap, outer_map_name)) {
                ret = create_map_in_map(obj, inner_map, &imap, -1, NULL);
                if (ret < 0)
                        return ret;

                inner_fd = bpf_map__fd(inner_map);
                outer_map = bpf_object__find_map_by_name(obj, outer_map_name);
                ret = create_map_in_map(obj, outer_map, &omap, inner_fd, &reuse_pin_map);
                if (ret < 0)
                        return ret;

                if (!reuse_pin_map) {
                        inner_idx = imap.inner_idx;
                        outer_fd = bpf_map__fd(outer_map);
                        ret = bpf_map_update_elem(outer_fd, &inner_idx, &inner_fd, 0);
                        if (ret < 0)
                                fprintf(stderr, "Cannot update inner_idx into outer_map\n");
                }
        }

        return ret;
}

static int find_legacy_tail_calls(struct bpf_program *prog, struct bpf_object *obj)
{
        unsigned int map_id, key_id;
        const char *sec_name;
        struct bpf_map *map;
        char map_name[128];
        int ret;

        /* Handle iproute2 tail call */
        sec_name = get_bpf_program__section_name(prog);
        ret = sscanf(sec_name, "%i/%i", &map_id, &key_id);
        if (ret != 2)
                return -1;

        ret = iproute2_find_map_name_by_id(map_id, map_name);
        if (ret < 0) {
                fprintf(stderr, "unable to find map id %u for tail call\n", map_id);
                return ret;
        }

        map = bpf_object__find_map_by_name(obj, map_name);
        if (!map)
                return -1;

        /* Save the map here for later updating */
        bpf_program__set_priv(prog, map, NULL);

        return 0;
}

static int update_legacy_tail_call_maps(struct bpf_object *obj)
{
        int prog_fd, map_fd, ret = 0;
        unsigned int map_id, key_id;
        struct bpf_program *prog;
        const char *sec_name;
        struct bpf_map *map;

        bpf_object__for_each_program(prog, obj) {
                map = bpf_program__priv(prog);
                if (!map)
                        continue;

                prog_fd = bpf_program__fd(prog);
                if (prog_fd < 0)
                        continue;

                sec_name = get_bpf_program__section_name(prog);
                ret = sscanf(sec_name, "%i/%i", &map_id, &key_id);
                if (ret != 2)
                        continue;

                map_fd = bpf_map__fd(map);
                ret = bpf_map_update_elem(map_fd, &key_id, &prog_fd, 0);
                if (ret < 0) {
                        fprintf(stderr, "Cannot update map key for tail call!\n");
                        return ret;
                }
        }

        return 0;
}

static int handle_legacy_maps(struct bpf_object *obj)
{
        char pathname[PATH_MAX];
        struct bpf_map *map;
        const char *map_name;
        int map_fd, ret = 0;

        bpf_object__for_each_map(map, obj) {
                map_name = bpf_map__name(map);

                ret = handle_legacy_map_in_map(obj, map, map_name);
                if (ret)
                        return ret;

                /* If it is a iproute2 legacy pin maps, just set pin path
                 * and let bpf_object__load() to deal with the map creation.
                 * We need to ignore map-in-maps which have pinned maps manually
                 */
                map_fd = bpf_map__fd(map);
                if (map_fd < 0 && iproute2_is_pin_map(map_name, pathname)) {
                        ret = bpf_map__set_pin_path(map, pathname);
                        if (ret) {
                                fprintf(stderr, "map '%s': couldn't set pin path.\n", map_name);
                                break;
                        }
                }

        }

        return ret;
}

static int load_bpf_object(struct bpf_cfg_in *cfg)
{
        struct bpf_program *p, *prog = NULL;
        struct bpf_object *obj;
        char root_path[PATH_MAX];
        struct bpf_map *map;
        int prog_fd, ret = 0;

        ret = iproute2_get_root_path(root_path, PATH_MAX);
        if (ret)
                return ret;

        DECLARE_LIBBPF_OPTS(bpf_object_open_opts, open_opts,
                        .relaxed_maps = true,
                        .pin_root_path = root_path,
        );

        obj = bpf_object__open_file(cfg->object, &open_opts);
        if (libbpf_get_error(obj)) {
                fprintf(stderr, "ERROR: opening BPF object file failed\n");
                return -ENOENT;
        }

        bpf_object__for_each_program(p, obj) {
                bool prog_to_attach = !prog && cfg->section &&
                        !strcmp(get_bpf_program__section_name(p), cfg->section);

                /* Only load the programs that will either be subsequently
                 * attached or inserted into a tail call map */
                if (find_legacy_tail_calls(p, obj) < 0 && !prog_to_attach) {
                        ret = bpf_program__set_autoload(p, false);
                        if (ret)
                                return -EINVAL;
                        continue;
                }

                bpf_program__set_type(p, cfg->type);
                bpf_program__set_ifindex(p, cfg->ifindex);

                if (prog_to_attach)
                        prog = p;
        }

        bpf_object__for_each_map(map, obj) {
                if (!bpf_map__is_offload_neutral(map))
                        bpf_map__set_ifindex(map, cfg->ifindex);
        }

        if (!prog) {
                fprintf(stderr, "object file doesn't contain sec %s\n", cfg->section);
                return -ENOENT;
        }

        /* Handle iproute2 legacy pin maps and map-in-maps */
        ret = handle_legacy_maps(obj);
        if (ret)
                goto unload_obj;

        ret = bpf_object__load(obj);
        if (ret)
                goto unload_obj;

        ret = update_legacy_tail_call_maps(obj);
        if (ret)
                goto unload_obj;

        prog_fd = fcntl(bpf_program__fd(prog), F_DUPFD_CLOEXEC, 1);
        if (prog_fd < 0)
                ret = -errno;
        else
                cfg->prog_fd = prog_fd;

unload_obj:
        /* Close obj as we don't need it */
        bpf_object__close(obj);
        return ret;
}

/* Load ebpf and return prog fd */
int iproute2_load_libbpf(struct bpf_cfg_in *cfg)
{
        int ret = 0;

        if (cfg->verbose)
                libbpf_set_print(verbose_print);
        else
                libbpf_set_print(silent_print);

        ret = iproute2_bpf_elf_ctx_init(cfg);
        if (ret < 0) {
                fprintf(stderr, "Cannot initialize ELF context!\n");
                return ret;
        }

        ret = iproute2_bpf_fetch_ancillary();
        if (ret < 0) {
                fprintf(stderr, "Error fetching ELF ancillary data!\n");
                return ret;
        }

        ret = load_bpf_object(cfg);
        if (ret)
                return ret;

        return cfg->prog_fd;
}