#include <linux/unistd.h>
#include <linux/bpf.h>

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>
#include <string.h>
#include <assert.h>
#include <errno.h>

#include <sys/types.h>
#include <sys/socket.h>

#include <bpf/bpf.h>

#include <bpf/libbpf.h>
#include "bpf_insn.h"
#include "sock_example.h"
#include "bpf_util.h"

#define BPF_F_PIN       (1 << 0)
#define BPF_F_GET       (1 << 1)
#define BPF_F_PIN_GET   (BPF_F_PIN | BPF_F_GET)

#define BPF_F_KEY       (1 << 2)
#define BPF_F_VAL       (1 << 3)
#define BPF_F_KEY_VAL   (BPF_F_KEY | BPF_F_VAL)

#define BPF_M_UNSPEC    0
#define BPF_M_MAP       1
#define BPF_M_PROG      2

char bpf_log_buf[BPF_LOG_BUF_SIZE];

static void usage(void)
{
        printf("Usage: fds_example [...]\n");
        printf("       -F <file>   File to pin/get object\n");
        printf("       -P          |- pin object\n");
        printf("       -G          `- get object\n");
        printf("       -m          eBPF map mode\n");
        printf("       -k <key>    |- map key\n");
        printf("       -v <value>  `- map value\n");
        printf("       -p          eBPF prog mode\n");
        printf("       -o <object> `- object file\n");
        printf("       -h          Display this help.\n");
}

static int bpf_prog_create(const char *object)
{
        static struct bpf_insn insns[] = {
                BPF_MOV64_IMM(BPF_REG_0, 1),
                BPF_EXIT_INSN(),
        };
        size_t insns_cnt = ARRAY_SIZE(insns);
        struct bpf_object *obj;
        int err;

        if (object) {
                obj = bpf_object__open_file(object, NULL);
                assert(!libbpf_get_error(obj));
                err = bpf_object__load(obj);
                assert(!err);
                return bpf_program__fd(bpf_object__next_program(obj, NULL));
        } else {
                LIBBPF_OPTS(bpf_prog_load_opts, opts,
                        .log_buf = bpf_log_buf,
                        .log_size = BPF_LOG_BUF_SIZE,
                );

                return bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL",
                                     insns, insns_cnt, &opts);
        }
}

static int bpf_do_map(const char *file, uint32_t flags, uint32_t key,
                      uint32_t value)
{
        int fd, ret;

        if (flags & BPF_F_PIN) {
                fd = bpf_map_create(BPF_MAP_TYPE_ARRAY, NULL, sizeof(uint32_t),
                                    sizeof(uint32_t), 1024, NULL);
                printf("bpf: map fd:%d (%s)\n", fd, strerror(errno));
                assert(fd > 0);

                ret = bpf_obj_pin(fd, file);
                printf("bpf: pin ret:(%d,%s)\n", ret, strerror(errno));
                assert(ret == 0);
        } else {
                fd = bpf_obj_get(file);
                printf("bpf: get fd:%d (%s)\n", fd, strerror(errno));
                assert(fd > 0);
        }

        if ((flags & BPF_F_KEY_VAL) == BPF_F_KEY_VAL) {
                ret = bpf_map_update_elem(fd, &key, &value, 0);
                printf("bpf: fd:%d u->(%u:%u) ret:(%d,%s)\n", fd, key, value,
                       ret, strerror(errno));
                assert(ret == 0);
        } else if (flags & BPF_F_KEY) {
                ret = bpf_map_lookup_elem(fd, &key, &value);
                printf("bpf: fd:%d l->(%u):%u ret:(%d,%s)\n", fd, key, value,
                       ret, strerror(errno));
                assert(ret == 0);
        }

        return 0;
}

static int bpf_do_prog(const char *file, uint32_t flags, const char *object)
{
        int fd, sock, ret;

        if (flags & BPF_F_PIN) {
                fd = bpf_prog_create(object);
                printf("bpf: prog fd:%d (%s)\n", fd, strerror(errno));
                assert(fd > 0);

                ret = bpf_obj_pin(fd, file);
                printf("bpf: pin ret:(%d,%s)\n", ret, strerror(errno));
                assert(ret == 0);
        } else {
                fd = bpf_obj_get(file);
                printf("bpf: get fd:%d (%s)\n", fd, strerror(errno));
                assert(fd > 0);
        }

        sock = open_raw_sock("lo");
        assert(sock > 0);

        ret = setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &fd, sizeof(fd));
        printf("bpf: sock:%d <- fd:%d attached ret:(%d,%s)\n", sock, fd,
               ret, strerror(errno));
        assert(ret == 0);

        return 0;
}

int main(int argc, char **argv)
{
        const char *file = NULL, *object = NULL;
        uint32_t key = 0, value = 0, flags = 0;
        int opt, mode = BPF_M_UNSPEC;

        while ((opt = getopt(argc, argv, "F:PGmk:v:po:")) != -1) {
                switch (opt) {
                /* General args */
                case 'F':
                        file = optarg;
                        break;
                case 'P':
                        flags |= BPF_F_PIN;
                        break;
                case 'G':
                        flags |= BPF_F_GET;
                        break;
                /* Map-related args */
                case 'm':
                        mode = BPF_M_MAP;
                        break;
                case 'k':
                        key = strtoul(optarg, NULL, 0);
                        flags |= BPF_F_KEY;
                        break;
                case 'v':
                        value = strtoul(optarg, NULL, 0);
                        flags |= BPF_F_VAL;
                        break;
                /* Prog-related args */
                case 'p':
                        mode = BPF_M_PROG;
                        break;
                case 'o':
                        object = optarg;
                        break;
                default:
                        goto out;
                }
        }

        if (!(flags & BPF_F_PIN_GET) || !file)
                goto out;

        switch (mode) {
        case BPF_M_MAP:
                return bpf_do_map(file, flags, key, value);
        case BPF_M_PROG:
                return bpf_do_prog(file, flags, object);
        }
out:
        usage();
        return -1;
}