/*
 * Copyright (C) 2000-2012 Free Software Foundation, Inc.
 *
 * Author: Nikos Mavrogiannopoulos
 *
 * This file is part of GnuTLS.
 *
 * The GnuTLS 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 program.  If not, see <http://www.gnu.org/licenses/>
 *
 */

/* Functions that relate to base64 encoding and decoding.
 */

#include "gnutls_int.h"
#include "gnutls_errors.h"
#include <gnutls_datum.h>
#include <x509_b64.h>
#include <base64.h>

#define INCR(what, size, max_len) \
	do { \
	what+=size; \
	if (what > max_len) { \
		gnutls_assert(); \
		gnutls_free( result->data); result->data = NULL; \
		return GNUTLS_E_INTERNAL_ERROR; \
	} \
	} while(0)

/* encodes data and puts the result into result (locally allocated)
 * The result_size (including the null terminator) is the return value.
 */
int
_gnutls_fbase64_encode (const char *msg, const uint8_t * data,
                        size_t data_size, gnutls_datum_t * result)
{
  int tmp;
  unsigned int i;
  char tmpres[66];
  uint8_t *ptr;
  char top[80];
  char bottom[80];
  size_t size, max, bytes;
  int pos, top_len, bottom_len;

  if (msg == NULL || strlen(msg) > 50)
    {
      gnutls_assert ();
      return GNUTLS_E_BASE64_ENCODING_ERROR;
    }

  _gnutls_str_cpy (top, sizeof(top), "-----BEGIN ");
  _gnutls_str_cat (top, sizeof(top), msg);
  _gnutls_str_cat (top, sizeof(top), "-----\n");

  _gnutls_str_cpy (bottom, sizeof(bottom), "-----END ");
  _gnutls_str_cat (bottom, sizeof(bottom), msg);
  _gnutls_str_cat (bottom, sizeof(bottom), "-----\n");

  top_len = strlen (top);
  bottom_len = strlen (bottom);

  max = B64FSIZE (top_len+bottom_len, data_size);

  result->data = gnutls_malloc (max + 1);
  if (result->data == NULL)
    {
      gnutls_assert ();
      return GNUTLS_E_MEMORY_ERROR;
    }

  bytes = pos = 0;
  INCR (bytes, top_len, max);
  pos = top_len;

  memcpy (result->data, top, top_len);

  for (i = 0; i < data_size; i += 48)
    {
      if (data_size - i < 48)
        tmp = data_size - i;
      else
        tmp = 48;

      base64_encode ((void*)&data[i], tmp, tmpres, sizeof(tmpres));
      size = strlen(tmpres);

      INCR (bytes, size+1, max);
      ptr = &result->data[pos];

      memcpy(ptr, tmpres, size);
      ptr += size;
      *ptr++ = '\n';

      pos += size + 1;
    }

  INCR (bytes, bottom_len, max);

  memcpy (&result->data[bytes - bottom_len], bottom, bottom_len);
  result->data[bytes] = 0;
  result->size = bytes;

  return max + 1;
}

/**
 * gnutls_pem_base64_encode:
 * @msg: is a message to be put in the header
 * @data: contain the raw data
 * @result: the place where base64 data will be copied
 * @result_size: holds the size of the result
 *
 * This function will convert the given data to printable data, using
 * the base64 encoding. This is the encoding used in PEM messages.
 *
 * The output string will be null terminated, although the size will
 * not include the terminating null.
 *
 * Returns: On success %GNUTLS_E_SUCCESS (0) is returned,
 *   %GNUTLS_E_SHORT_MEMORY_BUFFER is returned if the buffer given is
 *   not long enough, or 0 on success.
 **/
int
gnutls_pem_base64_encode (const char *msg, const gnutls_datum_t * data,
                          char *result, size_t * result_size)
{
  gnutls_datum_t res;
  int ret;

  ret = _gnutls_fbase64_encode (msg, data->data, data->size, &res);
  if (ret < 0)
    return ret;

  if (result == NULL || *result_size < (unsigned) res.size)
    {
      gnutls_free (res.data);
      *result_size = res.size + 1;
      return GNUTLS_E_SHORT_MEMORY_BUFFER;
    }
  else
    {
      memcpy (result, res.data, res.size);
      gnutls_free (res.data);
      *result_size = res.size;
    }

  return 0;
}

/**
 * gnutls_pem_base64_encode_alloc:
 * @msg: is a message to be put in the encoded header
 * @data: contains the raw data
 * @result: will hold the newly allocated encoded data
 *
 * This function will convert the given data to printable data, using
 * the base64 encoding.  This is the encoding used in PEM messages.
 * This function will allocate the required memory to hold the encoded
 * data.
 *
 * You should use gnutls_free() to free the returned data.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise
 *   an error code is returned.
 **/
int
gnutls_pem_base64_encode_alloc (const char *msg,
                                const gnutls_datum_t * data,
                                gnutls_datum_t * result)
{
  int ret;

  if (result == NULL)
    return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

  ret = _gnutls_fbase64_encode (msg, data->data, data->size, result);
  if (ret < 0)
    return gnutls_assert_val(ret);

  return 0;
}

/* copies data to result but removes newlines and <CR>
 * returns the size of the data copied.
 */
inline static int
cpydata (const uint8_t * data, int data_size, gnutls_datum_t *result)
{
  int i, j;

  result->data = gnutls_malloc (data_size+1);
  if (result->data == NULL)
    return GNUTLS_E_MEMORY_ERROR;

  for (j = i = 0; i < data_size; i++)
    {
      if (data[i] == '\n' || data[i] == '\r' || data[i] == ' '
          || data[i] == '\t')
        continue;
      else if (data[i] == '-') break;
      result->data[j] = data[i];
      j++;
    }
  
  result->size = j;
  result->data[j] = 0;
  return j;
}

/* decodes data and puts the result into result (locally allocated)
 * The result_size is the return value
 */
int
_gnutls_base64_decode (const uint8_t * data, size_t data_size,
                       gnutls_datum_t * result)
{
  unsigned int i;
  int pos, tmp, est, ret;
  uint8_t tmpres[48];
  size_t tmpres_size, decode_size;
  gnutls_datum_t pdata;

  ret = cpydata(data, data_size, &pdata);
  if (ret < 0)
    {
      gnutls_assert();
      return ret;
    }

  est = ((data_size * 3) / 4) + 1;
  
  result->data = gnutls_malloc (est);
  if (result->data == NULL)
    return gnutls_assert_val(GNUTLS_E_MEMORY_ERROR);

  pos = 0;
  for (i = 0; i < pdata.size; i += 64)
    {
      if (pdata.size - i < 64)
        decode_size = pdata.size - i;
      else
        decode_size = 64;
    
      tmpres_size = sizeof(tmpres);
      tmp = base64_decode ((void*)&pdata.data[i], decode_size, (void*)tmpres, &tmpres_size);
      if (tmp == 0)
        {
          gnutls_assert();
          gnutls_free (result->data);
          result->data = NULL;
          ret = GNUTLS_E_PARSING_ERROR;
          goto cleanup;
        }
      memcpy (&result->data[pos], tmpres, tmpres_size);
      pos += tmpres_size;
    }

  result->size = pos;

  ret = pos;

cleanup:
  gnutls_free (pdata.data);
  return ret;
}


/* Searches the given string for ONE PEM encoded certificate, and
 * stores it in the result.
 *
 * The result_size is the return value
 */
#define ENDSTR "-----"
int
_gnutls_fbase64_decode (const char *header, const uint8_t * data,
                        size_t data_size, gnutls_datum_t* result)
{
  int ret;
  static const char top[] = "-----BEGIN ";
  static const char bottom[] = "-----END ";
  uint8_t *rdata, *kdata;
  int rdata_size;
  char pem_header[128];

  _gnutls_str_cpy (pem_header, sizeof (pem_header), top);
  if (header != NULL)
    _gnutls_str_cat (pem_header, sizeof (pem_header), header);

  rdata = memmem (data, data_size, pem_header, strlen (pem_header));

  if (rdata == NULL)
    {
      gnutls_assert ();
      _gnutls_debug_log ("Could not find '%s'\n", pem_header);
      return GNUTLS_E_BASE64_UNEXPECTED_HEADER_ERROR;
    }

  data_size -= (unsigned long int) rdata - (unsigned long int) data;

  if (data_size < 4 + strlen (bottom))
    {
      gnutls_assert ();
      return GNUTLS_E_BASE64_DECODING_ERROR;
    }

  kdata = memmem (rdata + 1, data_size - 1, ENDSTR, sizeof (ENDSTR) - 1);
  /* allow CR as well.
   */
  if (kdata == NULL)
    {
      gnutls_assert ();
      _gnutls_debug_log ("Could not find '%s'\n", ENDSTR);
      return GNUTLS_E_BASE64_DECODING_ERROR;
    }
  data_size -= strlen (ENDSTR);
  data_size -= (unsigned long int) kdata - (unsigned long int) rdata;

  rdata = kdata + strlen (ENDSTR);

  /* position is now after the ---BEGIN--- headers */

  kdata = memmem (rdata, data_size, bottom, strlen (bottom));
  if (kdata == NULL)
    {
      gnutls_assert ();
      return GNUTLS_E_BASE64_DECODING_ERROR;
    }

  /* position of kdata is before the ----END--- footer 
   */
  rdata_size = (unsigned long int) kdata - (unsigned long int) rdata;

  if (rdata_size < 4)
    {
      gnutls_assert ();
      return GNUTLS_E_BASE64_DECODING_ERROR;
    }

  if ((ret = _gnutls_base64_decode (rdata, rdata_size, result)) < 0)
    {
      gnutls_assert ();
      return GNUTLS_E_BASE64_DECODING_ERROR;
    }

  return ret;
}

/**
 * gnutls_pem_base64_decode:
 * @header: A null terminated string with the PEM header (eg. CERTIFICATE)
 * @b64_data: contain the encoded data
 * @result: the place where decoded data will be copied
 * @result_size: holds the size of the result
 *
 * This function will decode the given encoded data.  If the header
 * given is non null this function will search for "-----BEGIN header"
 * and decode only this part.  Otherwise it will decode the first PEM
 * packet found.
 *
 * Returns: On success %GNUTLS_E_SUCCESS (0) is returned,
 *   %GNUTLS_E_SHORT_MEMORY_BUFFER is returned if the buffer given is
 *   not long enough, or 0 on success.
 **/
int
gnutls_pem_base64_decode (const char *header,
                          const gnutls_datum_t * b64_data,
                          unsigned char *result, size_t * result_size)
{
  gnutls_datum_t res;
  int ret;

  ret =
    _gnutls_fbase64_decode (header, b64_data->data, b64_data->size, &res);
  if (ret < 0)
    return gnutls_assert_val(ret);

  if (result == NULL || *result_size < (unsigned) res.size)
    {
      gnutls_free (res.data);
      *result_size = res.size;
      return GNUTLS_E_SHORT_MEMORY_BUFFER;
    }
  else
    {
      memcpy (result, res.data, res.size);
      gnutls_free (res.data);
      *result_size = res.size;
    }

  return 0;
}

/**
 * gnutls_pem_base64_decode_alloc:
 * @header: The PEM header (eg. CERTIFICATE)
 * @b64_data: contains the encoded data
 * @result: the place where decoded data lie
 *
 * This function will decode the given encoded data. The decoded data
 * will be allocated, and stored into result.  If the header given is
 * non null this function will search for "-----BEGIN header" and
 * decode only this part. Otherwise it will decode the first PEM
 * packet found.
 *
 * You should use gnutls_free() to free the returned data.
 *
 * Returns: On success, %GNUTLS_E_SUCCESS (0) is returned, otherwise
 *   an error code is returned.
 **/
int
gnutls_pem_base64_decode_alloc (const char *header,
                                const gnutls_datum_t * b64_data,
                                gnutls_datum_t * result)
{
  int ret;

  if (result == NULL)
    return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);

  ret =
    _gnutls_fbase64_decode (header, b64_data->data, b64_data->size, result);
  if (ret < 0)
    return gnutls_assert_val(ret);

  return 0;
}