/****************************************************************************
 * apps/netutils/codecs/base64.c
 *
 * This file is part of the NuttX RTOS:
 *
 *   Copyright (C) 2012 Gregory Nutt. All rights reserved.
 *   Author: Darcy Gong
 *
 * Reference:
 *
 *   Base64 encoding/decoding (RFC1341)
 *   Copyright (c) 2005, Jouni Malinen <jkmaline@cc.hut.fi>
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License version 2 as
 *   published by the Free Software Foundation.
 *
 *   Alternatively, this software may be distributed under the terms of BSD
 *   license.
 *
 *   See README and COPYING for more details.
 *
 * And is re-released under the NuttX modified BSD license:
 *
 *   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.
 *   3. Neither the name of the Institute nor the names of its contributors
 *      may be used to endorse or promote products derived from this software
 *      without specific prior written permission.
 *
 *   THIS SOFTWARE IS PROVIDED BY THE INSTITUTE 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 INSTITUTE 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.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <stdlib.h>
#include <stdbool.h>
#include <string.h>

#include "netutils/base64.h"

#ifdef CONFIG_CODECS_BASE64

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: base64_tab
 ****************************************************************************/

static void base64_tab(unsigned char *tab, size_t len, bool websafe)
{
  static const char *_tab =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

  memset(tab, 0, len);
  if (len >= 64)
    {
      memcpy(tab, _tab, 64);
    }

  if (websafe)
    {
      tab[62] = '-';
      tab[63] = '_';
    }
}

/****************************************************************************
 * Name: _base64_encode
 *
 * Description:
 *   Base64 encode
 *
 *   Caller is responsible for freeing the returned buffer. Returned buffer
 *   is nul terminated to make it easier to use as a C string. The nul
 *   terminator is not included in out_len.
 *
 * Input Parameters:
 *   src: Data to be encoded
 *   len: Length of the data to be encoded
 *   out_len: Pointer to output length variable, or NULL if not used
 *
 * Returned Value:
 *   Returns: Allocated buffer of out_len bytes of encoded data,
 *   or NULL on failure
 *
 ****************************************************************************/

static unsigned char *_base64_encode(const unsigned char *src, size_t len,
                                     unsigned char *dst, size_t * out_len,
                                     bool websafe)
{
  unsigned char *out;
  unsigned char *pos;
  const unsigned char *end;
  const unsigned char *in;
  size_t olen;
/*int line_len; */
  unsigned char base64_table[64];
  char ch = '=';

  if (websafe)
    {
      ch = '.';
    }

  base64_tab(base64_table, sizeof(base64_table), websafe);
  olen = len * 4 / 3 + 4;       /* 3-byte blocks to 4-byte */

#if 0
  olen += olen / 72; /* line feeds */
  olen++; /* nul termination */
  out = malloc(olen);
  if (out == NULL)
    {
      return NULL;
    }
#endif

  end = src + len;
  in = src;

  if (dst)
    {
      pos = out = dst;
    }
  else
    {
      pos = out = malloc(olen);
      if (out == NULL)
        {
          return NULL;
        }
    }

/*line_len = 0; */
  while (end - in >= 3)
    {
      *pos++ = base64_table[in[0] >> 2];
      *pos++ = base64_table[((in[0] & 0x03) << 4) | (in[1] >> 4)];
      *pos++ = base64_table[((in[1] & 0x0f) << 2) | (in[2] >> 6)];
      *pos++ = base64_table[in[2] & 0x3f];
      in += 3;
   /* line_len += 4; */
    }

  if (end - in)
    {
      *pos++ = base64_table[in[0] >> 2];
      if (end - in == 1)
        {
          *pos++ = base64_table[(in[0] & 0x03) << 4];
          *pos++ = ch;          /* *pos++ = '='; */
        }
      else
        {
          *pos++ = base64_table[((in[0] & 0x03) << 4) | (in[1] >> 4)];
          *pos++ = base64_table[(in[1] & 0x0f) << 2];
        }
      *pos++ = ch;              /* *pos++ = '='; */
   /* line_len += 4; */
    }

#if 0
  if (line_len)
    {
      *pos++ = '\n';
    }
#endif

  *pos = '\0';
  if (out_len)
    {
      *out_len = pos - out;
    }

/*out[*out_len] = '\0'; */
  return out;
}

/****************************************************************************
 * Name: _base64_decode
 *
 * Description:
 *   Base64 decode
 *
 * Caller is responsible for freeing the returned buffer.
 *
 * Input Parameters:
 *   src: Data to be decoded
 *   len: Length of the data to be decoded
 *   out_len: Pointer to output length variable
 *
 * Returned Value:
 *   Returns: Allocated buffer of out_len bytes of decoded data,
 *   or NULL on failure
 *
 ****************************************************************************/

static unsigned char *_base64_decode(const unsigned char *src, size_t len,
                              unsigned char *dst, size_t * out_len,
                              bool websafe)
{
  unsigned char dtable[256];
  unsigned char *out;
  unsigned char *pos;
  unsigned char in[4];
  unsigned char block[4];
  unsigned char tmp;
  size_t count;
  size_t i;
  unsigned char base64_table[64];
  char ch = '=';

  if (websafe)
    {
      ch = '.';
    }
  base64_tab(base64_table, sizeof(base64_table), websafe);

  memset(dtable, 0x80, 256);
  for (i = 0; i < sizeof(base64_table); i++)
    {
      dtable[base64_table[i]] = i;
    }

  dtable[(int)ch] = 0;          /* dtable['='] = 0; */

  count = 0;
  for (i = 0; i < len; i++)
    {
      if (dtable[src[i]] != 0x80)
        {
          count++;
        }
    }

  if (count % 4)
    {
      return NULL;
    }

  if (dst)
    {
      pos = out = dst;
    }
  else
    {
      pos = out = malloc(count);
      if (out == NULL)
        {
          return NULL;
        }
    }

  count = 0;
  for (i = 0; i < len; i++)
    {
      tmp = dtable[src[i]];
      if (tmp == 0x80)
        {
          continue;
        }

      in[count] = src[i];
      block[count] = tmp;
      count++;
      if (count == 4)
        {
          *pos++ = (block[0] << 2) | (block[1] >> 4);
          *pos++ = (block[1] << 4) | (block[2] >> 2);
          *pos++ = (block[2] << 6) | block[3];
          count = 0;
        }
    }

  if (pos > out)
    {
      if (in[2] == ch)          /* if (in[2] == '=') */
        {
          pos -= 2;
        }
      else if (in[3] == ch)     /* else if (in[3] == '=') */
        {
          pos--;
        }
    }

  *out_len = pos - out;
  return out;
}

/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: base64_encode
 ****************************************************************************/

unsigned char *base64_encode(const unsigned char *src, size_t len,
                             unsigned char *dst, size_t * out_len)
{
  return _base64_encode(src, len, dst, out_len, false);
}

/****************************************************************************
 * Name: base64_decode
 ****************************************************************************/

unsigned char *base64_decode(const unsigned char *src, size_t len,
                             unsigned char *dst, size_t * out_len)
{
  return _base64_decode(src, len, dst, out_len, false);
}

/****************************************************************************
 * Name: base64w_encode
 ****************************************************************************/

unsigned char *base64w_encode(const unsigned char *src, size_t len,
                              unsigned char *dst, size_t * out_len)
{
  return _base64_encode(src, len, dst, out_len, true);
}

/****************************************************************************
 * Name: base64w_decode
 ****************************************************************************/

unsigned char *base64w_decode(const unsigned char *src, size_t len,
                              unsigned char *dst, size_t * out_len)
{
  return _base64_decode(src, len, dst, out_len, true);
}

#endif /* CONFIG_CODECS_BASE64 */