/* gbase64.c - Base64 encoding/decoding

 *

 *  Copyright (C) 2006 Alexander Larsson <alexl@redhat.com>

 *  Copyright (C) 2000-2003 Ximian Inc.

 *

 * SPDX-License-Identifier: LGPL-2.1-or-later

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public License

 * along with this library; if not, see <http://www.gnu.org/licenses/>.

 *

 * This is based on code in camel, written by:

 *    Michael Zucchi <notzed@ximian.com>

 *    Jeffrey Stedfast <fejj@ximian.com>

 */

#include "config.h"

#include <string.h>

#include "gbase64.h"

#include "gtestutils.h"

#include "glibintl.h"

/**

 * SECTION:base64

 * @title: Base64 Encoding

 * @short_description: encodes and decodes data in Base64 format

 *

 * Base64 is an encoding that allows a sequence of arbitrary bytes to be

 * encoded as a sequence of printable ASCII characters. For the definition

 * of Base64, see 

 * [RFC 1421](http://www.ietf.org/rfc/rfc1421.txt)

 * or

 * [RFC 2045](http://www.ietf.org/rfc/rfc2045.txt).

 * Base64 is most commonly used as a MIME transfer encoding

 * for email.

 *

 * GLib supports incremental encoding using g_base64_encode_step() and

 * g_base64_encode_close(). Incremental decoding can be done with

 * g_base64_decode_step(). To encode or decode data in one go, use

 * g_base64_encode() or g_base64_decode(). To avoid memory allocation when

 * decoding, you can use g_base64_decode_inplace().

 *

 * Support for Base64 encoding has been added in GLib 2.12.

 */

static const char base64_alphabet[] =

        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

/**

 * g_base64_encode_step:

 * @in: (array length=len) (element-type guint8): the binary data to encode

 * @len: the length of @in

 * @break_lines: whether to break long lines

 * @out: (out) (array) (element-type guint8): pointer to destination buffer

 * @state: (inout): Saved state between steps, initialize to 0

 * @save: (inout): Saved state between steps, initialize to 0

 *

 * Incrementally encode a sequence of binary data into its Base-64 stringified

 * representation. By calling this function multiple times you can convert

 * data in chunks to avoid having to have the full encoded data in memory.

 *

 * When all of the data has been converted you must call

 * g_base64_encode_close() to flush the saved state.

 *

 * The output buffer must be large enough to fit all the data that will

 * be written to it. Due to the way base64 encodes you will need

 * at least: (@len / 3 + 1) * 4 + 4 bytes (+ 4 may be needed in case of

 * non-zero state). If you enable line-breaking you will need at least:

 * ((@len / 3 + 1) * 4 + 4) / 76 + 1 bytes of extra space.

 *

 * @break_lines is typically used when putting base64-encoded data in emails.

 * It breaks the lines at 76 columns instead of putting all of the text on

 * the same line. This avoids problems with long lines in the email system.

 * Note however that it breaks the lines with `LF` characters, not

 * `CR LF` sequences, so the result cannot be passed directly to SMTP

 * or certain other protocols.

 *

 * Returns: The number of bytes of output that was written

 *

 * Since: 2.12

 */

gsize

g_base64_encode_step (const guchar *in,

                      gsize         len,

                      gboolean      break_lines,

                      gchar        *out,

                      gint         *state,

                      gint         *save)

{

  char *outptr;

  const guchar *inptr;

  g_return_val_if_fail (in != NULL || len == 0, 0);

  g_return_val_if_fail (out != NULL, 0);

  g_return_val_if_fail (state != NULL, 0);

  g_return_val_if_fail (save != NULL, 0);

  if (len == 0)

    return 0;

  inptr = in;

  outptr = out;

  if (len + ((char *) save) [0] > 2)

    {

      const guchar *inend = in+len-2;

      int c1, c2, c3;

      int already;

      already = *state;

      switch (((char *) save) [0])

        {

        case 1:

          c1 = ((unsigned char *) save) [1];

          goto skip1;

        case 2:

          c1 = ((unsigned char *) save) [1];

          c2 = ((unsigned char *) save) [2];

          goto skip2;

        }

      /*

       * yes, we jump into the loop, no i'm not going to change it,

       * it's beautiful!

       */

      while (inptr < inend)

        {

          c1 = *inptr++;

        skip1:

          c2 = *inptr++;

        skip2:

          c3 = *inptr++;

          *outptr++ = base64_alphabet [ c1 >> 2 ];

          *outptr++ = base64_alphabet [ c2 >> 4 |

                                        ((c1&0x3) << 4) ];

          *outptr++ = base64_alphabet [ ((c2 &0x0f) << 2) |

                                        (c3 >> 6) ];

          *outptr++ = base64_alphabet [ c3 & 0x3f ];

          /* this is a bit ugly ... */

          if (break_lines && (++already) >= 19)

            {

              *outptr++ = '\n';

              already = 0;

            }

        }

      ((char *)save)[0] = 0;

      len = 2 - (inptr - inend);

      *state = already;

    }

  g_assert (len == 0 || len == 1 || len == 2);

    {

      char *saveout;

      /* points to the slot for the next char to save */

      saveout = & (((char *)save)[1]) + ((char *)save)[0];

      /* len can only be 0 1 or 2 */

      switch(len)

        {

        case 2:

          *saveout++ = *inptr++;

          G_GNUC_FALLTHROUGH;

        case 1:

          *saveout++ = *inptr++;

        }

      ((char *)save)[0] += len;

    }

  return outptr - out;

}

/**

 * g_base64_encode_close:

 * @break_lines: whether to break long lines

 * @out: (out) (array) (element-type guint8): pointer to destination buffer

 * @state: (inout): Saved state from g_base64_encode_step()

 * @save: (inout): Saved state from g_base64_encode_step()

 *

 * Flush the status from a sequence of calls to g_base64_encode_step().

 *

 * The output buffer must be large enough to fit all the data that will

 * be written to it. It will need up to 4 bytes, or up to 5 bytes if

 * line-breaking is enabled.

 *

 * The @out array will not be automatically nul-terminated.

 *

 * Returns: The number of bytes of output that was written

 *

 * Since: 2.12

 */

gsize

g_base64_encode_close (gboolean  break_lines,

                       gchar    *out,

                       gint     *state,

                       gint     *save)

{

  int c1, c2;

  char *outptr = out;

  g_return_val_if_fail (out != NULL, 0);

  g_return_val_if_fail (state != NULL, 0);

  g_return_val_if_fail (save != NULL, 0);

  c1 = ((unsigned char *) save) [1];

  c2 = ((unsigned char *) save) [2];

  switch (((char *) save) [0])

    {

    case 2:

      outptr [2] = base64_alphabet[ ( (c2 &0x0f) << 2 ) ];

      g_assert (outptr [2] != 0);

      goto skip;

    case 1:

      outptr[2] = '=';

      c2 = 0;  /* saved state here is not relevant */

    skip:

      outptr [0] = base64_alphabet [ c1 >> 2 ];

      outptr [1] = base64_alphabet [ c2 >> 4 | ( (c1&0x3) << 4 )];

      outptr [3] = '=';

      outptr += 4;

      break;

    }

  if (break_lines)

    *outptr++ = '\n';

  *save = 0;

  *state = 0;

  return outptr - out;

}

/**

 * g_base64_encode:

 * @data: (array length=len) (element-type guint8) (nullable): the binary data to encode

 * @len: the length of @data

 *

 * Encode a sequence of binary data into its Base-64 stringified

 * representation.

 *

 * Returns: (transfer full): a newly allocated, zero-terminated Base-64

 *               encoded string representing @data. The returned string must

 *               be freed with g_free().

 *

 * Since: 2.12

 */

gchar *

g_base64_encode (const guchar *data,

                 gsize         len)

{

  gchar *out;

  gint state = 0, outlen;

  gint save = 0;

  g_return_val_if_fail (data != NULL || len == 0, NULL);

  /* We can use a smaller limit here, since we know the saved state is 0,

     +1 is needed for trailing \0, also check for unlikely integer overflow */

  g_return_val_if_fail (len < ((G_MAXSIZE - 1) / 4 - 1) * 3, NULL);

  out = g_malloc ((len / 3 + 1) * 4 + 1);

  outlen = g_base64_encode_step (data, len, FALSE, out, &state, &save);

  outlen += g_base64_encode_close (FALSE, out + outlen, &state, &save);

  out[outlen] = '\0';

  return (gchar *) out;

}

static const unsigned char mime_base64_rank[256] = {

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

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

  255,255,255,255,255,255,255,255,255,255,255, 62,255,255,255, 63,

   52, 53, 54, 55, 56, 57, 58, 59, 60, 61,255,255,255,  0,255,255,

  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, 51,255,255,255,255,255,

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

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

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

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

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

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

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

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

};

/**

 * g_base64_decode_step: (skip)

 * @in: (array length=len) (element-type guint8): binary input data

 * @len: max length of @in data to decode

 * @out: (out caller-allocates) (array) (element-type guint8): output buffer

 * @state: (inout): Saved state between steps, initialize to 0

 * @save: (inout): Saved state between steps, initialize to 0

 *

 * Incrementally decode a sequence of binary data from its Base-64 stringified

 * representation. By calling this function multiple times you can convert

 * data in chunks to avoid having to have the full encoded data in memory.

 *

 * The output buffer must be large enough to fit all the data that will

 * be written to it. Since base64 encodes 3 bytes in 4 chars you need

 * at least: (@len / 4) * 3 + 3 bytes (+ 3 may be needed in case of non-zero

 * state).

 *

 * Returns: The number of bytes of output that was written

 *

 * Since: 2.12

 **/

gsize

g_base64_decode_step (const gchar  *in,

                      gsize         len,

                      guchar       *out,

                      gint         *state,

                      guint        *save)

{

  const guchar *inptr;

  guchar *outptr;

  const guchar *inend;

  guchar c, rank;

  guchar last[2];

  unsigned int v;

  int i;

  g_return_val_if_fail (in != NULL || len == 0, 0);

  g_return_val_if_fail (out != NULL, 0);

  g_return_val_if_fail (state != NULL, 0);

  g_return_val_if_fail (save != NULL, 0);

  if (len == 0)

    return 0;

  inend = (const guchar *)in+len;

  outptr = out;

  /* convert 4 base64 bytes to 3 normal bytes */

  v=*save;

  i=*state;

  last[0] = last[1] = 0;

  /* we use the sign in the state to determine if we got a padding character

     in the previous sequence */

  if (i < 0)

    {

      i = -i;

      last[0] = '=';

    }

  inptr = (const guchar *)in;

  while (inptr < inend)

    {

      c = *inptr++;

      rank = mime_base64_rank [c];

      if (rank != 0xff)

        {

          last[1] = last[0];

          last[0] = c;

          v = (v<<6) | rank;

          i++;

          if (i==4)

            {

              *outptr++ = v>>16;

              if (last[1] != '=')

                *outptr++ = v>>8;

              if (last[0] != '=')

                *outptr++ = v;

              i=0;

            }

        }

    }

  *save = v;

  *state = last[0] == '=' ? -i : i;

  return outptr - out;

}

/**

 * g_base64_decode:

 * @text: (not nullable): zero-terminated string with base64 text to decode

 * @out_len: (out): The length of the decoded data is written here

 *

 * Decode a sequence of Base-64 encoded text into binary data.  Note

 * that the returned binary data is not necessarily zero-terminated,

 * so it should not be used as a character string.

 *

 * Returns: (transfer full) (array length=out_len) (element-type guint8):

 *               newly allocated buffer containing the binary data

 *               that @text represents. The returned buffer must

 *               be freed with g_free().

 *

 * Since: 2.12

 */

guchar *

g_base64_decode (const gchar *text,

                 gsize       *out_len)

{

  guchar *ret;

  gsize input_length;

  gint state = 0;

  guint save = 0;

  g_return_val_if_fail (text != NULL, NULL);

  g_return_val_if_fail (out_len != NULL, NULL);

  input_length = strlen (text);

  /* We can use a smaller limit here, since we know the saved state is 0,

     +1 used to avoid calling g_malloc0(0), and hence returning NULL */

  ret = g_malloc0 ((input_length / 4) * 3 + 1);

  *out_len = g_base64_decode_step (text, input_length, ret, &state, &save);

  return ret;

}

/**

 * g_base64_decode_inplace:

 * @text: (inout) (array length=out_len) (element-type guint8): zero-terminated

 *        string with base64 text to decode

 * @out_len: (inout): The length of the decoded data is written here

 *

 * Decode a sequence of Base-64 encoded text into binary data

 * by overwriting the input data.

 *

 * Returns: (transfer none): The binary data that @text responds. This pointer

 *               is the same as the input @text.

 *

 * Since: 2.20

 */

guchar *

g_base64_decode_inplace (gchar *text,

                         gsize *out_len)

{

  gint input_length, state = 0;

  guint save = 0;

  g_return_val_if_fail (text != NULL, NULL);

  g_return_val_if_fail (out_len != NULL, NULL);

  input_length = strlen (text);

  g_return_val_if_fail (input_length > 1, NULL);

  *out_len = g_base64_decode_step (text, input_length, (guchar *) text, &state, &save);

  return (guchar *) text;

}