/***************************************************************************

 *                                  _   _ ____  _

 *  Project                     ___| | | |  _ \| |

 *                             / __| | | | |_) | |

 *                            | (__| |_| |  _ <| |___

 *                             \___|\___/|_| \_\_____|

 *

 * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.

 *

 * This software is licensed as described in the file COPYING, which

 * you should have received as part of this distribution. The terms

 * are also available at https://curl.se/docs/copyright.html.

 *

 * You may opt to use, copy, modify, merge, publish, distribute and/or sell

 * copies of the Software, and permit persons to whom the Software is

 * furnished to do so, under the terms of the COPYING file.

 *

 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY

 * KIND, either express or implied.

 *

 * SPDX-License-Identifier: curl

 *

 ***************************************************************************/

/* Base64 encoding/decoding */

#include "../curl_setup.h"

#include <curl/curl.h>

#include "warnless.h"

#include "base64.h"

/* ---- Base64 Encoding/Decoding Table --- */

const char Curl_base64encdec[] =

  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

/* The Base 64 encoding with a URL and filename safe alphabet, RFC 4648

   section 5 */

static const char base64url[] =

  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";

static const unsigned char decodetable[] = {

  62,  255, 255, 255, 63,  52,  53, 54, 55, 56, 57, 58, 59, 60, 61, 255,

  255, 255, 255, 255, 255, 255, 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,

  255, 255, 255, 255, 255, 255, 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

};

/*

 * curlx_base64_decode()

 *

 * Given a base64 null-terminated string at src, decode it and return a

 * pointer in *outptr to a newly allocated memory area holding decoded data.

 * Size of decoded data is returned in variable pointed by outlen.

 *

 * Returns CURLE_OK on success, otherwise specific error code. Function

 * output shall not be considered valid unless CURLE_OK is returned.

 *

 * When decoded data length is 0, returns NULL in *outptr.

 *

 * @unittest: 1302

 */

CURLcode curlx_base64_decode(const char *src,

                             uint8_t **outptr, size_t *outlen)

{

  size_t srclen = 0;

  size_t padding = 0;

  size_t i;

  size_t numQuantums;

  size_t fullQuantums;

  size_t rawlen = 0;

  unsigned char *pos;

  unsigned char *newstr;

  unsigned char lookup[256];

  *outptr = NULL;

  *outlen = 0;

  srclen = strlen(src);

  /* Check the length of the input string is valid */

  if(!srclen || srclen % 4)

    return CURLE_BAD_CONTENT_ENCODING;

  /* srclen is at least 4 here */

  while(src[srclen - 1 - padding] == '=') {

    /* count padding characters */

    padding++;

    /* A maximum of two = padding characters is allowed */

    if(padding > 2)

      return CURLE_BAD_CONTENT_ENCODING;

  }

  /* Calculate the number of quantums */

  numQuantums = srclen / 4;

  fullQuantums = numQuantums - (padding ? 1 : 0);

  /* Calculate the size of the decoded string */

  rawlen = (numQuantums * 3) - padding;

  /* Allocate our buffer including room for a null-terminator */

  newstr = curlx_malloc(rawlen + 1);

  if(!newstr)

    return CURLE_OUT_OF_MEMORY;

  pos = newstr;

  memset(lookup, 0xff, sizeof(lookup));

  memcpy(&lookup['+'], decodetable, sizeof(decodetable));

  /* Decode the complete quantums first */

  for(i = 0; i < fullQuantums; i++) {

    unsigned char val;

    unsigned int x = 0;

    int j;

    for(j = 0; j < 4; j++) {

      val = lookup[(unsigned char)*src++];

      if(val == 0xff) /* bad symbol */

        goto bad;

      x = (x << 6) | val;

    }

    pos[2] = x & 0xff;

    pos[1] = (x >> 8) & 0xff;

    pos[0] = (x >> 16) & 0xff;

    pos += 3;

  }

  if(padding) {

    /* this means either 8 or 16 bits output */

    unsigned char val;

    unsigned int x = 0;

    int j;

    size_t padc = 0;

    for(j = 0; j < 4; j++) {

      if(*src == '=') {

        x <<= 6;

        src++;

        if(++padc > padding)

          /* this is a badly placed '=' symbol! */

          goto bad;

      }

      else {

        val = lookup[(unsigned char)*src++];

        if(val == 0xff) /* bad symbol */

          goto bad;

        x = (x << 6) | val;

      }

    }

    if(padding == 1)

      pos[1] = (x >> 8) & 0xff;

    pos[0] = (x >> 16) & 0xff;

    pos += 3 - padding;

  }

  /* Zero terminate */

  *pos = '\0';

  /* Return the decoded data */

  *outptr = newstr;

  *outlen = rawlen;

  return CURLE_OK;

bad:

  curlx_free(newstr);

  return CURLE_BAD_CONTENT_ENCODING;

}

static CURLcode base64_encode(const char *table64,

                              uint8_t padbyte,

                              const uint8_t *inputbuff, size_t insize,

                              char **outptr, size_t *outlen)

{

  char *output;

  char *base64data;

  const unsigned char *in = (const unsigned char *)inputbuff;

  *outptr = NULL;

  *outlen = 0;

  if(!insize)

    return CURLE_OK;

  /* safety precaution */

  DEBUGASSERT(insize <= CURL_MAX_BASE64_INPUT);

  if(insize > CURL_MAX_BASE64_INPUT)

    return CURLE_TOO_LARGE;

  base64data = output = curlx_malloc((insize + 2) / 3 * 4 + 1);

  if(!output)

    return CURLE_OUT_OF_MEMORY;

  while(insize >= 3) {

    *output++ = table64[in[0] >> 2];

    *output++ = table64[((in[0] & 0x03) << 4) | (in[1] >> 4)];

    *output++ = table64[((in[1] & 0x0F) << 2) | ((in[2] & 0xC0) >> 6)];

    *output++ = table64[in[2] & 0x3F];

    insize -= 3;

    in += 3;

  }

  if(insize) {

    /* this is only one or two bytes now */

    *output++ = table64[in[0] >> 2];

    if(insize == 1) {

      *output++ = table64[((in[0] & 0x03) << 4)];

      if(padbyte) {

        *output++ = padbyte;

        *output++ = padbyte;

      }

    }

    else {

      /* insize == 2 */

      *output++ = table64[((in[0] & 0x03) << 4) | ((in[1] & 0xF0) >> 4)];

      *output++ = table64[((in[1] & 0x0F) << 2)];

      if(padbyte)

        *output++ = padbyte;

    }

  }

  /* Zero terminate */

  *output = '\0';

  /* Return the pointer to the new data (allocated memory) */

  *outptr = base64data;

  /* Return the length of the new data */

  *outlen = (size_t)(output - base64data);

  return CURLE_OK;

}

/*

 * curlx_base64_encode()

 *

 * Given a pointer to an input buffer and an input size, encode it and

 * return a pointer in *outptr to a newly allocated memory area holding

 * encoded data. Size of encoded data is returned in variable pointed by

 * outlen.

 *

 * Returns CURLE_OK on success, otherwise specific error code. Function

 * output shall not be considered valid unless CURLE_OK is returned.

 *

 * @unittest: 1302

 */

CURLcode curlx_base64_encode(const uint8_t *inputbuff, size_t insize,

                             char **outptr, size_t *outlen)

{

  return base64_encode(Curl_base64encdec, '=',

                       inputbuff, insize, outptr, outlen);

}

/*

 * curlx_base64url_encode()

 *

 * Given a pointer to an input buffer and an input size, encode it and

 * return a pointer in *outptr to a newly allocated memory area holding

 * encoded data. Size of encoded data is returned in variable pointed by

 * outlen.

 *

 * Input length of 0 indicates input buffer holds a null-terminated string.

 *

 * Returns CURLE_OK on success, otherwise specific error code. Function

 * output shall not be considered valid unless CURLE_OK is returned.

 *

 * @unittest: 1302

 */

CURLcode curlx_base64url_encode(const uint8_t *inputbuff, size_t insize,

                                char **outptr, size_t *outlen)

{

  return base64_encode(base64url, 0, inputbuff, insize, outptr, outlen);

}