/*-
 * Copyright (c) 2003 - 2016 Rozhuk Ivan <rozhuk.im@gmail.com>
 * Copyright (c) 2018 sss <sss at dark-alexandr dot net>
 * 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 REGENTS 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 REGENTS 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.
 *
 */

#pragma once

static const uint8_t *base64_url_tbl_coding = (const uint8_t
	*)"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
static const uint8_t base64_url_tbl_decoding[256] = {64, 64, 64, 64, 64, 64, 64,
    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    62, 64, 64, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 64, 64, 64, 64, 64, 64,
    64, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
    20, 21, 22, 23, 24, 25, 64, 64, 64, 64, 63, 64, 26, 27, 28, 29, 30, 31, 32,
    33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,
    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
    64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64};

static inline int
base64_url_encode(uint8_t *src, size_t src_size, uint8_t *dst, size_t dst_size,
    size_t *enc_size)
{
	size_t tm, src_m3_size;
	register uint8_t *wpos, *rpos, *src_m3_max;

	if (NULL == src || 0 == src_size)
		return (EINVAL);
	/* dst buf size calculation. */
	tm = (src_size / 3);
	src_m3_size = (tm * 3);
	if (src_m3_size != src_size)
	{ /* is multiple of 3? */
		tm++;
	}
	tm *= 4;
	if (NULL != enc_size)
	{
		(*enc_size) = tm;
	}
	if (dst_size < tm) /* Is dst buf too small? */
		return (ENOBUFS);
	if (NULL == dst)
		return (EINVAL);
	wpos = dst;
	rpos = src;
	/* Main loop: encode 3 -> 4 */
	for (src_m3_max = (src + src_m3_size); rpos < src_m3_max; rpos += 3)
	{
		(*wpos++) = base64_url_tbl_coding[rpos[0] >> 2]; /* c1 */
		(*wpos++)
		    = base64_url_tbl_coding[((rpos[0] << 4) & 0x30)
					    | ((rpos[1] >> 4) & 0x0f)]; /* c2 */
		(*wpos++)
		    = base64_url_tbl_coding[((rpos[1] << 2) & 0x3c)
					    | ((rpos[2] >> 6) & 0x03)]; /* c3 */
		(*wpos++) = base64_url_tbl_coding[rpos[2] & 0x3f];	/* c4 */
	}
	/* Tail special encoding. */
	if (src_size != src_m3_size)
	{ /* If src_size was not a multiple of 3: 1-2 bytes tail special coding.
	   */
		(*wpos++) = base64_url_tbl_coding[rpos[0] >> 2]; /* c1 */
		if (1 == (src_size - src_m3_size))
		{ /* 1 byte tail. */
			(*wpos++) = base64_url_tbl_coding[(
			    (rpos[0] << 4) & 0x30)]; /* c2 */
			(*wpos++) = '=';	     /* c3: tail padding. */
		}
		else
		{ /* 2 bytes tail. */
			(*wpos++)
			    = base64_url_tbl_coding[((rpos[0] << 4) & 0x30)
						    | ((rpos[1] >> 4)
							& 0x0f)]; /* c2 */
			(*wpos++) = base64_url_tbl_coding[(
			    (rpos[1] << 2) & 0x3c)]; /* c3 */
		}
		(*wpos++) = '='; /* c4: tail padding. */
	}
	(*wpos) = 0;
#if 0
	if ((wpos - dst) != tm) { /* Must be euqual! */
		(*enc_size) = (wpos - dst);
	}
#endif

	return (0);
}

static inline int
base64_url_decode(uint8_t *src, size_t src_size, uint8_t *dst, size_t dst_size,
    size_t *dcd_size)
{
	size_t tm, src_m4_size;
	register uint8_t *wpos, *rpos, *src_m4_max;

	if (NULL == src || 2 > src_size)
		return (EINVAL);
	/* Remove tail padding. */
	for (; 0 < src_size; src_size--)
	{
		if ('=' != src[(src_size - 1)])
			break;
	}
	if (2 > src_size) /* Check again: at least 2 byte needed for decoder. */
		return (EINVAL);
	/* dst buf size calculation. */
	tm = (src_size / 4);
	src_m4_size = (tm * 4);
	if (src_m4_size != src_size)
	{ /* is multiple of 4? */
		tm++;
	}
	tm *= 3;
	if (dst_size < tm)
	{ /* Is dst buf too small? */
		if (NULL != dcd_size)
		{
			(*dcd_size) = tm;
		}
		return (ENOBUFS);
	}
	if (NULL == dst)
		return (EINVAL);
	wpos = dst;
	rpos = src;
	/* Main loop: decode 4 -> 3 */
	for (src_m4_max = (src + src_m4_size); rpos < src_m4_max; rpos += 4)
	{
		(*wpos++) = (base64_url_tbl_decoding[rpos[0]] << 2
			     | base64_url_tbl_decoding[rpos[1]] >> 4);
		(*wpos++) = (base64_url_tbl_decoding[rpos[1]] << 4
			     | base64_url_tbl_decoding[rpos[2]] >> 2);
		(*wpos++) = (base64_url_tbl_decoding[rpos[2]] << 6
			     | base64_url_tbl_decoding[rpos[3]]);
	}
	/* Tail special decoding. */
	switch ((src_size - src_m4_size))
	{
		case 2:
			(*wpos++) = (base64_url_tbl_decoding[rpos[0]] << 2
				     | base64_url_tbl_decoding[rpos[1]] >> 4);
			break;
		case 3:
			(*wpos++) = (base64_url_tbl_decoding[rpos[0]] << 2
				     | base64_url_tbl_decoding[rpos[1]] >> 4);
			(*wpos++) = (base64_url_tbl_decoding[rpos[1]] << 4
				     | base64_url_tbl_decoding[rpos[2]] >> 2);
			break;
	}
	(*wpos) = 0;
	if (NULL != dcd_size)
	{ /* Real decoded size can be smaller than calculated. */
		(*dcd_size) = (wpos - dst);
	}

	return (0);
}