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/*
This file is part of TALER
Copyright (C) 2014, 2015, 2016 Taler Systems SA
TALER is free software; you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation; either version 3, or (at your option) any later version.
TALER 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 General Public License for more details.
You should have received a copy of the GNU General Public License along with
TALER; see the file COPYING. If not, see <http://www.gnu.org/licenses/>
*/
/**
* @file json/json.c
* @brief helper functions for JSON processing using libjansson
* @author Sree Harsha Totakura <sreeharsha@totakura.in>
*/
#include "platform.h"
#include <gnunet/gnunet_util_lib.h>
#include "taler_util.h"
#include "taler_json_lib.h"
/**
* Hash a JSON object for binary signing.
*
* See https://tools.ietf.org/html/draft-rundgren-json-canonicalization-scheme-15
* for fun JSON canonicalization problems. Callers must ensure that
* those are avoided in the input. We will use libjanson's "JSON_COMPACT"
* encoding for whitespace and "JSON_SORT_KEYS" to canonicalize as best
* as we can.
*
* @param[in] json some JSON value
* @param[out] hc resulting hash code
* @return #GNUNET_OK on success, #GNUNET_SYSERR on error
*/
int
TALER_JSON_hash (const json_t *json,
struct GNUNET_HashCode *hc)
{
char *wire_enc;
size_t len;
if (NULL == (wire_enc = json_dumps (json,
JSON_COMPACT | JSON_SORT_KEYS)))
{
GNUNET_break (0);
return GNUNET_SYSERR;
}
len = strlen (wire_enc) + 1;
GNUNET_CRYPTO_hash (wire_enc,
len,
hc);
free (wire_enc);
return GNUNET_OK;
}
/**
* Extract the Taler error code from the given @a json object.
* Note that #TALER_EC_NONE is returned if no "code" is present.
*
* @param json response to extract the error code from
* @return the "code" value from @a json
*/
enum TALER_ErrorCode
TALER_JSON_get_error_code (const json_t *json)
{
const json_t *jc;
if (NULL == json)
{
GNUNET_break_op (0);
return TALER_EC_INVALID_RESPONSE;
}
jc = json_object_get (json, "code");
/* The caller already knows that the JSON represents an error,
so we are dealing with a missing error code here. */
if (NULL == jc)
{
GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
"Expected Taler error code `code' in JSON, but field does not exist!\n");
return TALER_EC_INVALID;
}
if (json_is_integer (jc))
return (enum TALER_ErrorCode) json_integer_value (jc);
GNUNET_break_op (0);
return TALER_EC_INVALID;
}
/**
* Extract the Taler error hint from the given @a json object.
* Note that NULL is returned if no "hint" is present.
*
* @param json response to extract the error hint from
* @return the "hint" value from @a json; only valid as long as @a json is valid
*/
const char *
TALER_JSON_get_error_hint (const json_t *json)
{
const json_t *jc;
if (NULL == json)
{
GNUNET_break_op (0);
return NULL;
}
jc = json_object_get (json, "hint");
if (NULL == jc)
return NULL; /* no hint, is allowed */
if (! json_is_string (jc))
{
/* Hints must be strings */
GNUNET_break_op (0);
return NULL;
}
return json_string_value (jc);
}
/**
* Extract the Taler error code from the given @a data object, which is expected to be in JSON.
* Note that #TALER_EC_INVALID is returned if no "code" is present or if @a data is not in JSON.
*
* @param data response to extract the error code from
* @param data_size number of bytes in @a data
* @return the "code" value from @a json
*/
enum TALER_ErrorCode
TALER_JSON_get_error_code2 (const void *data,
size_t data_size)
{
json_t *json;
enum TALER_ErrorCode ec;
json_error_t err;
json = json_loads (data,
data_size,
&err);
if (NULL == json)
return TALER_EC_INVALID;
ec = TALER_JSON_get_error_code (json);
json_decref (json);
if (ec == TALER_EC_NONE)
return TALER_EC_INVALID;
return ec;
}
/* End of json/json.c */
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