/*      $OpenBSD: bn_shift.c,v 1.9 2023/03/11 14:02:26 jsing Exp $ */
/*
 * Copyright (c) 2022 Joel Sing <jsing@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/time.h>

#include <err.h>
#include <signal.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#include <openssl/bn.h>

static const char *bn_shift_want_hex = \
    "02AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA" \
    "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA8";

static int
check_shift_result(BIGNUM *bn1)
{
        BIGNUM *bn2 = NULL;
        char *s = NULL;
        int ret = 0;

        if (!BN_hex2bn(&bn2, bn_shift_want_hex)) {
                fprintf(stderr, "FAIL: BN_hex2bn() failed\n");
                goto failure;
        }
        if (BN_cmp(bn1, bn2) != 0) {
                fprintf(stderr, "FAIL: shifted result differs\n");
                if ((s = BN_bn2hex(bn1)) == NULL) {
                        fprintf(stderr, "FAIL: BN_bn2hex()\n");
                        goto failure;
                }
                fprintf(stderr, "Got:  %s\n", s);
                free(s);
                if ((s = BN_bn2hex(bn2)) == NULL) {
                        fprintf(stderr, "FAIL: BN_bn2hex()\n");
                        goto failure;
                }
                fprintf(stderr, "Want: %s\n", s);
        }

        ret = 1;

 failure:
        BN_free(bn2);
        free(s);

        return ret;
}

static int
test_bn_shift1(void)
{
        BIGNUM *bn1 = NULL, *bn2 = NULL;
        int i;
        int failed = 1;

        if ((bn1 = BN_new()) == NULL) {
                fprintf(stderr, "FAIL: failed to create BN\n");
                goto failure;
        }
        if ((bn2 = BN_new()) == NULL) {
                fprintf(stderr, "FAIL: failed to create BN\n");
                goto failure;
        }

        for (i = 1; i <= 256; i++) {
                if (!BN_set_bit(bn1, 1)) {
                        fprintf(stderr, "FAIL: failed to set bit\n");
                        goto failure;
                }
                if (!BN_lshift1(bn1, bn1)) {
                        fprintf(stderr, "FAIL: failed to BN_lshift1()\n");
                        goto failure;
                }
                if (!BN_lshift1(bn1, bn1)) {
                        fprintf(stderr, "FAIL: failed to BN_lshift1()\n");
                        goto failure;
                }
                if (!BN_rshift1(bn1, bn1)) {
                        fprintf(stderr, "FAIL: failed to BN_rshift1()\n");
                        goto failure;
                }
                if (!BN_lshift1(bn1, bn1)) {
                        fprintf(stderr, "FAIL: failed to BN_lshift1()\n");
                        goto failure;
                }
        }

        if (!check_shift_result(bn1))
                goto failure;

        /*
         * Shift result into a different BN.
         */
        if (!BN_lshift1(bn1, bn1)) {
                fprintf(stderr, "FAIL: failed to BN_lshift1()\n");
                goto failure;
        }
        if (!BN_rshift1(bn2, bn1)) {
                fprintf(stderr, "FAIL: failed to BN_rshift1()\n");
                goto failure;
        }

        if (!check_shift_result(bn2))
                goto failure;

        if (!BN_rshift1(bn2, bn2)) {
                fprintf(stderr, "FAIL: failed to BN_rshift1()\n");
                goto failure;
        }
        if (!BN_lshift1(bn1, bn2)) {
                fprintf(stderr, "FAIL: failed to BN_lshift1()\n");
                goto failure;
        }

        if (!check_shift_result(bn1))
                goto failure;

        failed = 0;

 failure:
        BN_free(bn1);
        BN_free(bn2);

        return failed;
}

static int
test_bn_shift(void)
{
        BIGNUM *bn1 = NULL, *bn2 = NULL;
        int i;
        int failed = 1;

        if ((bn1 = BN_new()) == NULL) {
                fprintf(stderr, "FAIL: failed to create BN 1\n");
                goto failure;
        }
        if ((bn2 = BN_new()) == NULL) {
                fprintf(stderr, "FAIL: failed to create BN 2\n");
                goto failure;
        }

        for (i = 1; i <= 256; i++) {
                if (!BN_set_bit(bn1, 1)) {
                        fprintf(stderr, "FAIL: failed to set bit\n");
                        goto failure;
                }
                if (!BN_lshift(bn1, bn1, i + 1)) {
                        fprintf(stderr, "FAIL: failed to BN_lshift()\n");
                        goto failure;
                }
                if (!BN_rshift(bn1, bn1, i - 1)) {
                        fprintf(stderr, "FAIL: failed to BN_rshift()\n");
                        goto failure;
                }
        }

        if (!check_shift_result(bn1))
                goto failure;

        for (i = 0; i <= 256; i++) {
                if (!BN_lshift(bn1, bn1, i)) {
                        fprintf(stderr, "FAIL: failed to BN_lshift()\n");
                        goto failure;
                }
                if (i > 1) {
                        if (!BN_set_bit(bn1, 1)) {
                                fprintf(stderr, "FAIL: failed to set bit\n");
                                goto failure;
                        }
                }
        }

        if (BN_num_bytes(bn1) != 4177) {
                fprintf(stderr, "FAIL: BN has %d bytes, want 4177\n",
                    BN_num_bytes(bn1));
                goto failure;
        }

        for (i = 0; i <= 256; i++) {
                if (!BN_rshift(bn1, bn1, i)) {
                        fprintf(stderr, "FAIL: failed to BN_rshift()\n");
                        goto failure;
                }
        }

        if (!check_shift_result(bn1))
                goto failure;

        /*
         * Shift result into a different BN.
         */
        if (!BN_lshift(bn1, bn1, BN_BITS2 + 1)) {
                fprintf(stderr, "FAIL: failed to BN_lshift()\n");
                goto failure;
        }
        if (!BN_rshift(bn2, bn1, BN_BITS2 + 1)) {
                fprintf(stderr, "FAIL: failed to BN_rshift()\n");
                goto failure;
        }

        if (!check_shift_result(bn2))
                goto failure;

        if (!BN_rshift(bn2, bn2, 3)) {
                fprintf(stderr, "FAIL: failed to BN_rshift()\n");
                goto failure;
        }
        if (!BN_lshift(bn1, bn2, 3)) {
                fprintf(stderr, "FAIL: failed to BN_lshift()\n");
                goto failure;
        }

        if (!check_shift_result(bn1))
                goto failure;

        /*
         * Shift of zero (equivalent to a copy).
         */
        BN_zero(bn2);
        if (!BN_lshift(bn2, bn1, 0)) {
                fprintf(stderr, "FAIL: failed to BN_lshift()\n");
                goto failure;
        }

        if (!check_shift_result(bn2))
                goto failure;

        if (!BN_lshift(bn2, bn2, 0)) {
                fprintf(stderr, "FAIL: failed to BN_lshift()\n");
                goto failure;
        }

        if (!check_shift_result(bn2))
                goto failure;

        BN_zero(bn2);
        if (!BN_rshift(bn2, bn1, 0)) {
                fprintf(stderr, "FAIL: failed to BN_rshift()\n");
                goto failure;
        }

        if (!check_shift_result(bn2))
                goto failure;

        if (!BN_rshift(bn2, bn2, 0)) {
                fprintf(stderr, "FAIL: failed to BN_rshift()\n");
                goto failure;
        }

        if (!check_shift_result(bn2))
                goto failure;

        failed = 0;

 failure:
        BN_free(bn1);
        BN_free(bn2);

        return failed;
}

static int
test_bn_rshift_to_zero(void)
{
        BIGNUM *bn1 = NULL, *bn2 = NULL;
        int failed = 1;

        if (!BN_hex2bn(&bn1, "ffff")) {
                fprintf(stderr, "FAIL: BN_hex2bn() failed\n");
                goto failure;
        }
        if (!BN_lshift(bn1, bn1, BN_BITS2)) {
                fprintf(stderr, "FAIL: BN_lshift() failed\n");
                goto failure;
        }

        if ((bn2 = BN_new()) == NULL) {
                fprintf(stderr, "FAIL: BN_new() failed\n");
                goto failure;
        }

        /* Shift all words. */
        if (!BN_rshift(bn2, bn1, BN_BITS2 * 2)) {
                fprintf(stderr, "FAIL: BN_rshift() failed\n");
                goto failure;
        }
        if (BN_is_zero(bn1)) {
                fprintf(stderr, "FAIL: BN is zero\n");
                goto failure;
        }
        if (!BN_is_zero(bn2)) {
                fprintf(stderr, "FAIL: BN is not zero\n");
                goto failure;
        }

        /* Shift to zero, with partial shift for top most word. */
        if (!BN_rshift(bn2, bn1, BN_BITS2 + 16)) {
                fprintf(stderr, "FAIL: BN_rshift() failed\n");
                goto failure;
        }
        if (BN_is_zero(bn1)) {
                fprintf(stderr, "FAIL: BN is zero\n");
                goto failure;
        }
        if (!BN_is_zero(bn2)) {
                fprintf(stderr, "FAIL: BN is not zero\n");
                goto failure;
        }

        /* Shift to zero of negative value. */
        if (!BN_one(bn1)) {
                fprintf(stderr, "FAIL: BN_one() failed\n");
                goto failure;
        }
        BN_set_negative(bn1, 1);
        if (!BN_rshift(bn1, bn1, 1)) {
                fprintf(stderr, "FAIL: BN_rshift() failed\n");
                goto failure;
        }
        if (!BN_is_zero(bn1)) {
                fprintf(stderr, "FAIL: BN is not zero\n");
                goto failure;
        }
        if (BN_is_negative(bn1)) {
                fprintf(stderr, "FAIL: BN is negative zero\n");
                goto failure;
        }

        failed = 0;

 failure:
        BN_free(bn1);
        BN_free(bn2);

        return failed;
}

static void
benchmark_bn_lshift1(BIGNUM *bn)
{
        int i;

        if (!BN_set_bit(bn, 8192))
                errx(1, "BN_set_bit");

        if (!BN_one(bn))
                errx(1, "BN_one");

        for (i = 0; i < 8192; i++) {
                if (!BN_lshift1(bn, bn))
                        errx(1, "BN_lshift1");
        }
}

static void
benchmark_bn_lshift(BIGNUM *bn, int n)
{
        int i;

        if (!BN_set_bit(bn, 8192 * n))
                errx(1, "BN_set_bit");

        if (!BN_one(bn))
                errx(1, "BN_one");

        for (i = 0; i < 8192; i++) {
                if (!BN_lshift(bn, bn, n))
                        errx(1, "BN_lshift");
        }
}

static void
benchmark_bn_lshift_1(BIGNUM *bn)
{
        benchmark_bn_lshift(bn, 1);
}

static void
benchmark_bn_lshift_16(BIGNUM *bn)
{
        benchmark_bn_lshift(bn, 16);
}

static void
benchmark_bn_lshift_32(BIGNUM *bn)
{
        benchmark_bn_lshift(bn, 32);
}

static void
benchmark_bn_lshift_64(BIGNUM *bn)
{
        benchmark_bn_lshift(bn, 64);
}

static void
benchmark_bn_lshift_65(BIGNUM *bn)
{
        benchmark_bn_lshift(bn, 65);
}

static void
benchmark_bn_lshift_80(BIGNUM *bn)
{
        benchmark_bn_lshift(bn, 80);
}

static void
benchmark_bn_lshift_127(BIGNUM *bn)
{
        benchmark_bn_lshift(bn, 127);
}

static void
benchmark_bn_rshift1(BIGNUM *bn)
{
        int i;

        if (!BN_one(bn))
                errx(1, "BN_one");

        if (!BN_set_bit(bn, 8192))
                errx(1, "BN_set_bit");

        for (i = 0; i < 8192; i++) {
                if (!BN_rshift1(bn, bn))
                        errx(1, "BN_rshift1");
        }
}

static void
benchmark_bn_rshift(BIGNUM *bn, int n)
{
        int i;

        if (!BN_one(bn))
                errx(1, "BN_one");

        if (!BN_set_bit(bn, 8192 * n))
                errx(1, "BN_set_bit");

        for (i = 0; i < 8192; i++) {
                if (!BN_rshift(bn, bn, n))
                        errx(1, "BN_rshift");
        }
}

static void
benchmark_bn_rshift_1(BIGNUM *bn)
{
        benchmark_bn_rshift(bn, 1);
}

static void
benchmark_bn_rshift_16(BIGNUM *bn)
{
        benchmark_bn_rshift(bn, 16);
}

static void
benchmark_bn_rshift_32(BIGNUM *bn)
{
        benchmark_bn_rshift(bn, 32);
}

static void
benchmark_bn_rshift_64(BIGNUM *bn)
{
        benchmark_bn_rshift(bn, 64);
}

static void
benchmark_bn_rshift_65(BIGNUM *bn)
{
        benchmark_bn_rshift(bn, 65);
}

static void
benchmark_bn_rshift_80(BIGNUM *bn)
{
        benchmark_bn_rshift(bn, 80);
}

static void
benchmark_bn_rshift_127(BIGNUM *bn)
{
        benchmark_bn_rshift(bn, 127);
}

struct benchmark {
        const char *desc;
        void (*func)(BIGNUM *);
};

static const struct benchmark benchmarks[] = {
        {
                .desc = "BN_lshift1()",
                .func = benchmark_bn_lshift1,
        },
        {
                .desc = "BN_lshift(_, _, 1)",
                .func = benchmark_bn_lshift_1,
        },
        {
                .desc = "BN_lshift(_, _, 16)",
                .func = benchmark_bn_lshift_16,
        },
        {
                .desc = "BN_lshift(_, _, 32)",
                .func = benchmark_bn_lshift_32,
        },
        {
                .desc = "BN_lshift(_, _, 64)",
                .func = benchmark_bn_lshift_64,
        },
        {
                .desc = "BN_lshift(_, _, 65)",
                .func = benchmark_bn_lshift_65,
        },
        {
                .desc = "BN_lshift(_, _, 80)",
                .func = benchmark_bn_lshift_80,
        },
        {
                .desc = "BN_lshift(_, _, 127)",
                .func = benchmark_bn_lshift_127,
        },
        {
                .desc = "BN_rshift1()",
                .func = benchmark_bn_rshift1,
        },
        {
                .desc = "BN_rshift(_, _, 1)",
                .func = benchmark_bn_rshift_1,
        },
        {
                .desc = "BN_rshift(_, _, 16)",
                .func = benchmark_bn_rshift_16,
        },
        {
                .desc = "BN_rshift(_, _, 32)",
                .func = benchmark_bn_rshift_32,
        },
        {
                .desc = "BN_rshift(_, _, 64)",
                .func = benchmark_bn_rshift_64,
        },
        {
                .desc = "BN_rshift(_, _, 65)",
                .func = benchmark_bn_rshift_65,
        },
        {
                .desc = "BN_rshift(_, _, 80)",
                .func = benchmark_bn_rshift_80,
        },
        {
                .desc = "BN_rshift(_, _, 127)",
                .func = benchmark_bn_rshift_127,
        },
};

#define N_BENCHMARKS (sizeof(benchmarks) / sizeof(benchmarks[0]))

static volatile sig_atomic_t benchmark_stop;

static void
benchmark_sig_alarm(int sig)
{
        benchmark_stop = 1;
}

static void
benchmark_run(const struct benchmark *bm, int seconds)
{
        struct timespec start, end, duration;
        BIGNUM *bn;
        int i;

        signal(SIGALRM, benchmark_sig_alarm);

        if ((bn = BN_new()) == NULL)
                errx(1, "BN_new");

        benchmark_stop = 0;
        i = 0;
        alarm(seconds);

        clock_gettime(CLOCK_MONOTONIC, &start);

        fprintf(stderr, "Benchmarking %s for %ds: ", bm->desc, seconds);
        while (!benchmark_stop) {
                bm->func(bn);
                i++;
        }
        clock_gettime(CLOCK_MONOTONIC, &end);
        timespecsub(&end, &start, &duration);
        fprintf(stderr, "%d iterations in %f seconds\n", i,
            duration.tv_sec + duration.tv_nsec / 1000000000.0);

        BN_free(bn);
}

static void
benchmark_bn_shift(void)
{
        const struct benchmark *bm;
        size_t i;

        for (i = 0; i < N_BENCHMARKS; i++) {
                bm = &benchmarks[i];
                benchmark_run(bm, 5);
        }
}

int
main(int argc, char **argv)
{
        int benchmark = 0, failed = 0;

        if (argc == 2 && strcmp(argv[1], "--benchmark") == 0)
                benchmark = 1;

        failed |= test_bn_shift1();
        failed |= test_bn_shift();
        failed |= test_bn_rshift_to_zero();

        if (benchmark && !failed)
                benchmark_bn_shift();

        return failed;
}