/* 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 <sys/resource.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 */
static __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;
}
/* enum xdp_action */
#define XDP_UNKNOWN     XDP_REDIRECT + 1
#define XDP_ACTION_MAX (XDP_UNKNOWN + 1)
static const char *xdp_action_names[XDP_ACTION_MAX] = {
        [XDP_ABORTED]   = "XDP_ABORTED",
        [XDP_DROP]      = "XDP_DROP",
        [XDP_PASS]      = "XDP_PASS",
        [XDP_TX]        = "XDP_TX",
        [XDP_REDIRECT]  = "XDP_REDIRECT",
        [XDP_UNKNOWN]   = "XDP_UNKNOWN",
};
static const char *action2str(int action)
{
        if (action < XDP_ACTION_MAX)
                return xdp_action_names[action];
        return NULL;
}

struct record {
        __u64 counter;
        __u64 timestamp;
};

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

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

        printf("%-14s %-11s %-10s %-18s %-9s\n",
               "ACTION", "result", "pps ", "pps-human-readable", "measure-period");
}

static double calc_period(struct record *r, struct record *p)
{
        double period_ = 0;
        __u64 period = 0;

        period = r->timestamp - p->timestamp;
        if (period > 0)
                period_ = ((double) period / NANOSEC_PER_SEC);

        return period_;
}

static double calc_pps(struct record *r, struct record *p, double period)
{
        __u64 packets = 0;
        double pps = 0;

        if (period > 0) {
                packets = r->counter - p->counter;
                pps = packets / period;
        }
        return pps;
}

static void stats_print(struct stats_record *rec,
                        struct stats_record *prev,
                        bool err_only)
{
        double period = 0, pps = 0;
        struct record *r, *p;
        int i = 0;

        char *fmt = "%-14s %-11s %-10.0f %'-18.0f %f\n";

        /* tracepoint: xdp:xdp_redirect_* */
        if (err_only)
                i = REDIR_ERROR;

        for (; i < REDIR_RES_MAX; i++) {
                r = &rec->xdp_redir[i];
                p = &prev->xdp_redir[i];

                if (p->timestamp) {
                        period = calc_period(r, p);
                        pps = calc_pps(r, p, period);
                }
                printf(fmt, "XDP_REDIRECT", err2str(i), pps, pps, period);
        }

        /* tracepoint: xdp:xdp_exception */
        for (i = 0; i < XDP_ACTION_MAX; i++) {
                r = &rec->xdp_exception[i];
                p = &prev->xdp_exception[i];
                if (p->timestamp) {
                        period = calc_period(r, p);
                        pps = calc_pps(r, p, period);
                }
                if (pps > 0)
                        printf(fmt, action2str(i), "Exception",
                               pps, pps, period);
        }
        printf("\n");
}

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(struct stats_record *rec)
{
        int fd;
        int i;

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

        fd = map_data[0].fd; /* map0: redirect_err_cnt */
        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);
        }

        fd = map_data[1].fd; /* map1: exception_cnt */
        for (i = 0; i < XDP_ACTION_MAX; i++) {
                rec->xdp_exception[i].timestamp = gettime();
                rec->xdp_exception[i].counter = get_key32_value64_percpu(fd, i);
        }

        return true;
}

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

        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 map0: %s\n", map_data[0].name);
                printf(" - Stats map1: %s\n", map_data[1].name);
                printf("\n");
        }
        fflush(stdout);

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

static 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)
{
        struct rlimit r = {RLIM_INFINITY, RLIM_INFINITY};
        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 (setrlimit(RLIMIT_MEMLOCK, &r)) {
                perror("setrlimit(RLIMIT_MEMLOCK)");
                return EXIT_FAILURE;
        }

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

        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;
}