/* Copyright(c) 2017 Jesper Dangaard Brouer, Red Hat, Inc.
 */
static const char *__doc__=
 "XDP monitor tool, based on tracepoints\n"
;

static const char *__doc_err_only__=
 " NOTICE: Only tracking XDP redirect errors\n"
 "         Enable TX success stats via '--stats'\n"
 "         (which comes with a per packet processing overhead)\n"
;

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <stdint.h>
#include <string.h>
#include <ctype.h>
#include <unistd.h>
#include <locale.h>

#include <getopt.h>
#include <net/if.h>
#include <time.h>

#include "libbpf.h"
#include "bpf_load.h"
#include "bpf_util.h"

static int verbose = 1;
static bool debug = false;

static const struct option long_options[] = {
	{"help",	no_argument,		NULL, 'h' },
	{"debug",	no_argument,		NULL, 'D' },
	{"stats",	no_argument,		NULL, 'S' },
	{"sec", 	required_argument,	NULL, 's' },
	{0, 0, NULL,  0 }
};

static void usage(char *argv[])
{
	int i;
	printf("\nDOCUMENTATION:\n%s\n", __doc__);
	printf("\n");
	printf(" Usage: %s (options-see-below)\n",
	       argv[0]);
	printf(" Listing options:\n");
	for (i = 0; long_options[i].name != 0; i++) {
		printf(" --%-15s", long_options[i].name);
		if (long_options[i].flag != NULL)
			printf(" flag (internal value:%d)",
			       *long_options[i].flag);
		else
			printf("(internal short-option: -%c)",
			       long_options[i].val);
		printf("\n");
	}
	printf("\n");
}

#define NANOSEC_PER_SEC 1000000000 /* 10^9 */
__u64 gettime(void)
{
	struct timespec t;
	int res;

	res = clock_gettime(CLOCK_MONOTONIC, &t);
	if (res < 0) {
		fprintf(stderr, "Error with gettimeofday! (%i)\n", res);
		exit(EXIT_FAILURE);
	}
	return (__u64) t.tv_sec * NANOSEC_PER_SEC + t.tv_nsec;
}

enum {
	REDIR_SUCCESS = 0,
	REDIR_ERROR = 1,
};
#define REDIR_RES_MAX 2
static const char *redir_names[REDIR_RES_MAX] = {
	[REDIR_SUCCESS]	= "Success",
	[REDIR_ERROR]	= "Error",
};
static const char *err2str(int err)
{
	if (err < REDIR_RES_MAX)
		return redir_names[err];
	return NULL;
}

struct record {
	__u64 counter;
	__u64 timestamp;
};

struct stats_record {
	struct record xdp_redir[REDIR_RES_MAX];
};

static void stats_print_headers(bool err_only)
{
	if (err_only)
		printf("\n%s\n", __doc_err_only__);

	printf("%-14s %-10s %-18s %-9s\n",
	       "XDP_REDIRECT", "pps ", "pps-human-readable", "measure-period");
}

static void stats_print(struct stats_record *rec,
			struct stats_record *prev,
			bool err_only)
{
	int i = 0;

	if (err_only)
		i = REDIR_ERROR;

	for (; i < REDIR_RES_MAX; i++) {
		struct record *r = &rec->xdp_redir[i];
		struct record *p = &prev->xdp_redir[i];
		__u64 period  = 0;
		__u64 packets = 0;
		double pps = 0;
		double period_ = 0;

		if (p->timestamp) {
			packets = r->counter - p->counter;
			period  = r->timestamp - p->timestamp;
			if (period > 0) {
				period_ = ((double) period / NANOSEC_PER_SEC);
				pps = packets / period_;
			}
		}

		printf("%-14s %-10.0f %'-18.0f %f\n",
		       err2str(i), pps, pps, period_);
	}
}

static __u64 get_key32_value64_percpu(int fd, __u32 key)
{
	/* For percpu maps, userspace gets a value per possible CPU */
	unsigned int nr_cpus = bpf_num_possible_cpus();
	__u64 values[nr_cpus];
	__u64 sum = 0;
	int i;

	if ((bpf_map_lookup_elem(fd, &key, values)) != 0) {
		fprintf(stderr,
			"ERR: bpf_map_lookup_elem failed key:0x%X\n", key);
		return 0;
	}

	/* Sum values from each CPU */
	for (i = 0; i < nr_cpus; i++) {
		sum += values[i];
	}
	return sum;
}

static bool stats_collect(int fd, struct stats_record *rec)
{
	int i;

	/* TODO: Detect if someone unloaded the perf event_fd's, as
	 * this can happen by someone running perf-record -e
	 */

	for (i = 0; i < REDIR_RES_MAX; i++) {
		rec->xdp_redir[i].timestamp = gettime();
		rec->xdp_redir[i].counter = get_key32_value64_percpu(fd, i);
	}
	return true;
}

static void stats_poll(int interval, bool err_only)
{
	struct stats_record rec, prev;
	int map_fd;

	memset(&rec, 0, sizeof(rec));

	/* Trick to pretty printf with thousands separators use %' */
	setlocale(LC_NUMERIC, "en_US");

	/* Header */
	if (verbose)
		printf("\n%s", __doc__);

	/* TODO Need more advanced stats on error types */
	if (verbose)
		printf(" - Stats map: %s\n", map_data[0].name);
	map_fd = map_data[0].fd;

	stats_print_headers(err_only);
	fflush(stdout);

	while (1) {
		memcpy(&prev, &rec, sizeof(rec));
		stats_collect(map_fd, &rec);
		stats_print(&rec, &prev, err_only);
		fflush(stdout);
		sleep(interval);
	}
}

void print_bpf_prog_info(void)
{
	int i;

	/* Prog info */
	printf("Loaded BPF prog have %d bpf program(s)\n", prog_cnt);
	for (i = 0; i < prog_cnt; i++) {
		printf(" - prog_fd[%d] = fd(%d)\n", i, prog_fd[i]);
	}

	/* Maps info */
	printf("Loaded BPF prog have %d map(s)\n", map_data_count);
	for (i = 0; i < map_data_count; i++) {
		char *name = map_data[i].name;
		int fd     = map_data[i].fd;

		printf(" - map_data[%d] = fd(%d) name:%s\n", i, fd, name);
	}

	/* Event info */
	printf("Searching for (max:%d) event file descriptor(s)\n", prog_cnt);
	for (i = 0; i < prog_cnt; i++) {
		if (event_fd[i] != -1)
			printf(" - event_fd[%d] = fd(%d)\n", i, event_fd[i]);
	}
}

int main(int argc, char **argv)
{
	int longindex = 0, opt;
	int ret = EXIT_SUCCESS;
	char bpf_obj_file[256];

	/* Default settings: */
	bool errors_only = true;
	int interval = 2;

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

	/* Parse commands line args */
	while ((opt = getopt_long(argc, argv, "h",
				  long_options, &longindex)) != -1) {
		switch (opt) {
		case 'D':
			debug = true;
			break;
		case 'S':
			errors_only = false;
			break;
		case 's':
			interval = atoi(optarg);
			break;
		case 'h':
		default:
			usage(argv);
			return EXIT_FAILURE;
		}
	}

	if (load_bpf_file(bpf_obj_file)) {
		printf("ERROR - bpf_log_buf: %s", bpf_log_buf);
		return 1;
	}
	if (!prog_fd[0]) {
		printf("ERROR - load_bpf_file: %s\n", strerror(errno));
		return 1;
	}

	if (debug) {
		print_bpf_prog_info();
	}

	/* Unload/stop tracepoint event by closing fd's */
	if (errors_only) {
		/* The prog_fd[i] and event_fd[i] depend on the
		 * order the functions was defined in _kern.c
		 */
		close(event_fd[2]); /* tracepoint/xdp/xdp_redirect */
		close(prog_fd[2]);  /* func: trace_xdp_redirect */
		close(event_fd[3]); /* tracepoint/xdp/xdp_redirect_map */
		close(prog_fd[3]);  /* func: trace_xdp_redirect_map */
	}

	stats_poll(interval, errors_only);

	return ret;
}