/**

 * FreeRDP: A Remote Desktop Protocol Implementation

 * Base64 Encoding & Decoding

 *

 * Copyright 2011-2012 Marc-Andre Moreau <marcandre.moreau@gmail.com>

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *   http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

#include <freerdp/config.h>

#include <winpr/crt.h>

#include <freerdp/crypto/crypto.h>

static const char base64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

static const char base64url[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";

static char* base64_encode_ex(const char* alphabet, const BYTE* data, size_t length, BOOL pad,

                              BOOL crLf, size_t lineSize)

{

  int c = 0;

  const BYTE* q = NULL;

  char* p = NULL;

  char* ret = NULL;

  int blocks = 0;

  size_t outLen = (length + 3) * 4 / 3;

  size_t extra = 0;

  if (crLf)

  {

    size_t nCrLf = (outLen + lineSize - 1) / lineSize;

    extra = nCrLf * 2;

  }

  size_t outCounter = 0;

  q = data;

  p = ret = (char*)malloc(outLen + extra + 1ull);

  if (!p)

    return NULL;

  /* b1, b2, b3 are input bytes

   *

   * 0         1         2

   * 012345678901234567890123

   * |  b1  |  b2   |  b3   |

   *

   * [ c1 ]     [  c3 ]

   *      [  c2 ]     [  c4 ]

   *

   * c1, c2, c3, c4 are output chars in base64

   */

  /* first treat complete blocks */

  blocks = length - (length % 3);

  for (int i = 0; i < blocks; i += 3, q += 3)

  {

    c = (q[0] << 16) + (q[1] << 8) + q[2];

    *p++ = alphabet[(c & 0x00FC0000) >> 18];

    *p++ = alphabet[(c & 0x0003F000) >> 12];

    *p++ = alphabet[(c & 0x00000FC0) >> 6];

    *p++ = alphabet[c & 0x0000003F];

    outCounter += 4;

    if (crLf && (outCounter % lineSize == 0))

    {

      *p++ = '\r';

      *p++ = '\n';

    }

  }

  /* then remainder */

  switch (length % 3)

  {

    case 0:

      break;

    case 1:

      c = (q[0] << 16);

      *p++ = alphabet[(c & 0x00FC0000) >> 18];

      *p++ = alphabet[(c & 0x0003F000) >> 12];

      if (pad)

      {

        *p++ = '=';

        *p++ = '=';

      }

      break;

    case 2:

      c = (q[0] << 16) + (q[1] << 8);

      *p++ = alphabet[(c & 0x00FC0000) >> 18];

      *p++ = alphabet[(c & 0x0003F000) >> 12];

      *p++ = alphabet[(c & 0x00000FC0) >> 6];

      if (pad)

        *p++ = '=';

      break;

  }

  if (crLf && length % 3)

  {

    *p++ = '\r';

    *p++ = '\n';

  }

  *p = 0;

  return ret;

}

static char* base64_encode(const char* alphabet, const BYTE* data, size_t length, BOOL pad)

{

  return base64_encode_ex(alphabet, data, length, pad, FALSE, 64);

}

static int base64_decode_char(const char* alphabet, char c)

{

  char* p = NULL;

  if (c == '\0')

    return -1;

  if ((p = strchr(alphabet, c)))

    return p - alphabet;

  return -1;

}

static void* base64_decode(const char* alphabet, const char* s, size_t length, size_t* data_len,

                           BOOL pad)

{

  int n[4];

  BYTE* q = NULL;

  BYTE* data = NULL;

  size_t nBlocks = 0;

  size_t outputLen = 0;

  int remainder = length % 4;

  if ((pad && remainder > 0) || (remainder == 1))

    return NULL;

  if (!pad && remainder)

    length += 4 - remainder;

  q = data = (BYTE*)malloc(length / 4 * 3 + 1);

  if (!q)

    return NULL;

  /* first treat complete blocks */

  nBlocks = (length / 4);

  outputLen = 0;

  if (nBlocks < 1)

  {

    free(data);

    return NULL;

  }

  for (size_t i = 0; i < nBlocks - 1; i++, q += 3)

  {

    n[0] = base64_decode_char(alphabet, *s++);

    n[1] = base64_decode_char(alphabet, *s++);

    n[2] = base64_decode_char(alphabet, *s++);

    n[3] = base64_decode_char(alphabet, *s++);

    if ((n[0] == -1) || (n[1] == -1) || (n[2] == -1) || (n[3] == -1))

      goto out_free;

    q[0] = (n[0] << 2) + (n[1] >> 4);

    q[1] = ((n[1] & 15) << 4) + (n[2] >> 2);

    q[2] = ((n[2] & 3) << 6) + n[3];

    outputLen += 3;

  }

  /* treat last block */

  n[0] = base64_decode_char(alphabet, *s++);

  n[1] = base64_decode_char(alphabet, *s++);

  if ((n[0] == -1) || (n[1] == -1))

    goto out_free;

  n[2] = remainder == 2 ? -1 : base64_decode_char(alphabet, *s++);

  n[3] = remainder >= 2 ? -1 : base64_decode_char(alphabet, *s++);

  q[0] = (n[0] << 2) + (n[1] >> 4);

  if (n[2] == -1)

  {

    /* XX== */

    outputLen += 1;

    if (n[3] != -1)

      goto out_free;

    q[1] = ((n[1] & 15) << 4);

  }

  else if (n[3] == -1)

  {

    /* yyy= */

    outputLen += 2;

    q[1] = ((n[1] & 15) << 4) + (n[2] >> 2);

    q[2] = ((n[2] & 3) << 6);

  }

  else

  {

    /* XXXX */

    outputLen += 3;

    q[0] = (n[0] << 2) + (n[1] >> 4);

    q[1] = ((n[1] & 15) << 4) + (n[2] >> 2);

    q[2] = ((n[2] & 3) << 6) + n[3];

  }

  if (data_len)

    *data_len = outputLen;

  data[outputLen] = '\0';

  return data;

out_free:

  free(data);

  return NULL;

}

char* crypto_base64_encode_ex(const BYTE* data, size_t length, BOOL withCrLf)

{

  return base64_encode_ex(base64, data, length, TRUE, withCrLf, 64);

}

char* crypto_base64_encode(const BYTE* data, size_t length)

{

  return base64_encode(base64, data, length, TRUE);

}

void crypto_base64_decode(const char* enc_data, size_t length, BYTE** dec_data, size_t* res_length)

{

  *dec_data = base64_decode(base64, enc_data, length, res_length, TRUE);

}

char* crypto_base64url_encode(const BYTE* data, size_t length)

{

  return base64_encode(base64url, data, length, FALSE);

}

void crypto_base64url_decode(const char* enc_data, size_t length, BYTE** dec_data,

                             size_t* res_length)

{

  *dec_data = base64_decode(base64url, enc_data, length, res_length, FALSE);

}