path: root/src/json/json_helper.c

/*
  This file is part of GNUnet
  Copyright (C) 2014, 2015, 2016 GNUnet e.V.

  GNUnet is free software: you can redistribute it and/or modify it
  under the terms of the GNU Affero General Public License as published
  by the Free Software Foundation, either version 3 of the License,
  or (at your option) any later version.

  GNUnet 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
  Affero General Public License for more details.
 
  You should have received a copy of the GNU Affero General Public License
  along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/
/**
 * @file json/json_helper.c
 * @brief functions to generate specifciations for JSON parsing
 * @author Florian Dold
 * @author Benedikt Mueller
 * @author Christian Grothoff
 */
#include "platform.h"
#include "gnunet_json_lib.h"


/**
 * End of a parser specification.
 */
struct GNUNET_JSON_Specification
GNUNET_JSON_spec_end ()
{
  struct GNUNET_JSON_Specification ret = {
    .parser = NULL,
    .cleaner = NULL,
    .cls = NULL
  };
  return ret;
}


/**
 * Parse given JSON object to fixed size data
 *
 * @param cls closure, NULL
 * @param root the json object representing data
 * @param[out] spec where to write the data
 * @return #GNUNET_OK upon successful parsing; #GNUNET_SYSERR upon error
 */
static int
parse_fixed_data (void *cls,
                  json_t *root,
                  struct GNUNET_JSON_Specification *spec)
{
  const char *enc;
  unsigned int len;

  if (NULL == (enc = json_string_value (root)))
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  len = strlen (enc);
  if (((len * 5) / 8) != spec->ptr_size)
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  if (GNUNET_OK !=
      GNUNET_STRINGS_string_to_data (enc,
                                     len,
                                     spec->ptr,
                                     spec->ptr_size))
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  return GNUNET_OK;
}


/**
 * Variable size object (in network byte order, encoded using Crockford
 * Base32hex encoding).
 *
 * @param name name of the JSON field
 * @param[out] obj pointer where to write the data, must have @a size bytes
 * @param size number of bytes expected in @a obj
 */
struct GNUNET_JSON_Specification
GNUNET_JSON_spec_fixed (const char *name,
                        void *obj,
                        size_t size)
{
  struct GNUNET_JSON_Specification ret = {
    .parser = &parse_fixed_data,
    .cleaner = NULL,
    .cls = NULL,
    .field = name,
    .ptr = obj,
    .ptr_size = size,
    .size_ptr = NULL
  };
  return ret;
}


/**
 * Parse given JSON object to variable size data
 *
 * @param cls closure, NULL
 * @param root the json object representing data
 * @param[out] spec where to write the data
 * @return #GNUNET_OK upon successful parsing; #GNUNET_SYSERR upon error
 */
static int
parse_variable_data (void *cls,
                     json_t *root,
                     struct GNUNET_JSON_Specification *spec)
{
  const char *str;
  size_t size;
  void *data;
  int res;

  str = json_string_value (root);
  if (NULL == str)
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  size = (strlen (str) * 5) / 8;
  if (size >= 1024)
  {
    GNUNET_break_op (0);
    return GNUNET_SYSERR;
  }
  data = GNUNET_malloc (size);
  res = GNUNET_STRINGS_string_to_data (str,
                                       strlen (str),
                                       data,
                                       size);
  if (GNUNET_OK != res)
  {
    GNUNET_break_op (0);
    GNUNET_free (data);
    return GNUNET_SYSERR;
  }
  *(void**) spec->ptr = data;
  *spec->size_ptr = size;
  return GNUNET_OK;
}


/**
 * Cleanup data left from parsing variable size data
 *
 * @param cls closure, NULL
 * @param[out] spec where to free the data
 */
static void
clean_variable_data (void *cls,
                     struct GNUNET_JSON_Specification *spec)
{
  if (0 != *spec->size_ptr)
  {
    GNUNET_free (*(void **) spec->ptr);
    *(void**) spec->ptr = NULL;
    *spec->size_ptr = 0;
  }
}


/**
 * Variable size object (in network byte order, encoded using
 * Crockford Base32hex encoding).
 *
 * @param name name of the JSON field
 * @param[out] obj pointer where to write the data, will be allocated
 * @param[out] size where to store the number of bytes allocated for @a obj
 */
struct GNUNET_JSON_Specification
GNUNET_JSON_spec_varsize (const char *name,
                          void **obj,
                          size_t *size)
{
  struct GNUNET_JSON_Specification ret = {
    .parser = &parse_variable_data,
    .cleaner = &clean_variable_data,
    .cls = NULL,
    .field = name,
    .ptr = obj,
    .ptr_size = 0,
    .size_ptr = size
  };
  *obj = NULL;
  *size = 0;
  return ret;