/*-
 * Copyright (c) 2015 Taylor R. Campbell
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#define	_POSIX_C_SOURCE	200809L

#include <assert.h>
#include <err.h>
#include <stdio.h>

#include "freadline.h"
#include "hexdigit.h"
#include "unirandom.h"

#include "blake2b.h"

static const uint8_t key[BLAKE2B_MAX_KEY] = {
	0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,
	0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f,
	0x10,0x11,0x12,0x13,0x14,0x15,0x16,0x17,
	0x18,0x19,0x1a,0x1b,0x1c,0x1d,0x1e,0x1f,
	0x20,0x21,0x22,0x23,0x24,0x25,0x26,0x27,
	0x28,0x29,0x2a,0x2b,0x2c,0x2d,0x2e,0x2f,
	0x30,0x31,0x32,0x33,0x34,0x35,0x36,0x37,
	0x38,0x39,0x3a,0x3b,0x3c,0x3d,0x3e,0x3f,
};

int
main(int argc, char **argv)
{
	char hex[256*2 + 2];
	size_t len, n;
	unsigned char buf[256];
	struct blake2b ctx;
	uint8_t h[BLAKE2B_MAX_DIGEST];
	size_t lineno;
	unsigned i, c0, c1;

	(void)argc;		/* ignore */
	(void)argv;		/* ignore */

	if (blake2b_selftest() == -1)
		errx(1, "blake2b selftest failed");

	for (lineno = 1;
	     freadline(hex, sizeof(hex), &len, stdin) != EOF;
	     lineno++) {
		if (hex[len - 1] != '\n')
			errx(1, "line %zu too long", lineno);
		if (((len - 1) % 2) != 0)
			errx(1, "line %zu: odd number of hex digits", lineno);
		n = (len - 1) / 2;
		for (i = 0; i < n; i++) {
			unsigned char hi, lo;
			if (hexdigit(hex[2*i], &hi) == -1)
				errx(1, "line %zu char %u: invalid hex",
				    lineno, 2*i);
			if (hexdigit(hex[2*i + 1], &lo) == -1)
				errx(1, "line %zu char %u: invalid hex",
				    lineno, 2*i + 1);
			buf[i] = (hi << 4) | lo;
		}

		blake2b_init(&ctx, BLAKE2B_MAX_DIGEST, key, sizeof(key));
		if (n == 0) {
			if (unirandom(2))
				blake2b_update(&ctx, buf, 0);
		} else {
			c0 = unirandom(n);
			c1 = unirandom(n - c0);
			blake2b_update(&ctx, buf, c0);
			blake2b_update(&ctx, buf + c0, c1);
			blake2b_update(&ctx, buf + c0 + c1, n - (c0 + c1));
		}
		blake2b_final(&ctx, h);

		for (i = 0; i < sizeof(h); i++) {
			if (printf("%02hhx", h[i]) < 0)
				err(1, "printf");
		}
		if (printf("\n") < 0)
			err(1, "printf");
	}

	return 0;
}