// SPDX-License-Identifier: GPL-2.0-only

  /* Copyright (c) 2016 PLUMgrid

   */
  #include <linux/bpf.h>

  #include <linux/if_link.h>

  #include <assert.h>
  #include <errno.h>
  #include <signal.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>

  #include <unistd.h>

  #include <libgen.h>

  #include <sys/resource.h>

  #include <net/if.h>

  #include "bpf_util.h"

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

  static int ifindex;

  static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;

  static __u32 prog_id;

  
  static void int_exit(int sig)
  {

  	__u32 curr_prog_id = 0;
  
  	if (bpf_get_link_xdp_id(ifindex, &curr_prog_id, xdp_flags)) {
  		printf("bpf_get_link_xdp_id failed
  ");
  		exit(1);
  	}
  	if (prog_id == curr_prog_id)
  		bpf_set_link_xdp_fd(ifindex, -1, xdp_flags);
  	else if (!curr_prog_id)
  		printf("couldn't find a prog id on a given interface
  ");
  	else
  		printf("program on interface changed, not removing
  ");

  	exit(0);
  }
  
  /* simple per-protocol drop counter
   */

  static void poll_stats(int map_fd, int interval)

  {

  	unsigned int nr_cpus = bpf_num_possible_cpus();

  	__u64 values[nr_cpus], prev[UINT8_MAX] = { 0 };

  	int i;

  	while (1) {

  		__u32 key = UINT32_MAX;

  		sleep(interval);

  		while (bpf_map_get_next_key(map_fd, &key, &key) != -1) {

  			__u64 sum = 0;

  			assert(bpf_map_lookup_elem(map_fd, &key, values) == 0);

  			for (i = 0; i < nr_cpus; i++)

  				sum += values[i];
  			if (sum > prev[key])

  				printf("proto %u: %10llu pkt/s
  ",

  				       key, (sum - prev[key]) / interval);
  			prev[key] = sum;

  		}
  	}
  }

  static void usage(const char *prog)

  {

  	fprintf(stderr,

  		"usage: %s [OPTS] IFACE
  
  "

  		"OPTS:
  "

  		"    -S    use skb-mode
  "

  		"    -N    enforce native mode
  "
  		"    -F    force loading prog
  ",

  		prog);
  }

  int main(int argc, char **argv)
  {

  	struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};

  	struct bpf_prog_load_attr prog_load_attr = {
  		.prog_type	= BPF_PROG_TYPE_XDP,
  	};

  	struct bpf_prog_info info = {};
  	__u32 info_len = sizeof(info);

  	const char *optstr = "FSN";

  	int prog_fd, map_fd, opt;
  	struct bpf_object *obj;
  	struct bpf_map *map;

  	char filename[256];

  	int err;

  
  	while ((opt = getopt(argc, argv, optstr)) != -1) {
  		switch (opt) {
  		case 'S':

  			xdp_flags |= XDP_FLAGS_SKB_MODE;

  			break;

  		case 'N':

  			/* default, set below */

  			break;

  		case 'F':
  			xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
  			break;

  		default:
  			usage(basename(argv[0]));
  			return 1;
  		}
  	}

  	if (!(xdp_flags & XDP_FLAGS_SKB_MODE))
  		xdp_flags |= XDP_FLAGS_DRV_MODE;

  	if (optind == argc) {
  		usage(basename(argv[0]));

  		return 1;
  	}

  
  	if (setrlimit(RLIMIT_MEMLOCK, &r)) {
  		perror("setrlimit(RLIMIT_MEMLOCK)");
  		return 1;
  	}

  	ifindex = if_nametoindex(argv[optind]);

  	if (!ifindex) {
  		perror("if_nametoindex");
  		return 1;
  	}

  	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);

  	prog_load_attr.file = filename;

  	if (bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd))
  		return 1;
  
  	map = bpf_map__next(NULL, obj);
  	if (!map) {
  		printf("finding a map in obj file failed
  ");

  		return 1;
  	}

  	map_fd = bpf_map__fd(map);

  	if (!prog_fd) {

  		printf("bpf_prog_load_xattr: %s
  ", strerror(errno));

  		return 1;
  	}
  
  	signal(SIGINT, int_exit);

  	signal(SIGTERM, int_exit);

  	if (bpf_set_link_xdp_fd(ifindex, prog_fd, xdp_flags) < 0) {

  		printf("link set xdp fd failed
  ");
  		return 1;
  	}

  	err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
  	if (err) {
  		printf("can't get prog info - %s
  ", strerror(errno));
  		return err;
  	}
  	prog_id = info.id;

  	poll_stats(map_fd, 2);

  
  	return 0;
  }