asterisk/funcs/func_json.c

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2023-05-25 18:45:57 +00:00
/*
* Asterisk -- An open source telephony toolkit.
*
* Copyright (C) 2021, Naveen Albert
*
* See http://www.asterisk.org for more information about
* the Asterisk project. Please do not directly contact
* any of the maintainers of this project for assistance;
* the project provides a web site, mailing lists and IRC
* channels for your use.
*
* This program is free software, distributed under the terms of
* the GNU General Public License Version 2. See the LICENSE file
* at the top of the source tree.
*/
/*! \file
*
* \brief JSON parsing function
*
* \author Naveen Albert <asterisk@phreaknet.org>
*
* \ingroup functions
*/
/*** MODULEINFO
<support_level>extended</support_level>
***/
#include "asterisk.h"
#include "asterisk/module.h"
#include "asterisk/channel.h"
#include "asterisk/pbx.h"
#include "asterisk/utils.h"
#include "asterisk/test.h"
#include "asterisk/app.h"
#include "asterisk/conversions.h"
/*** DOCUMENTATION
<function name="JSON_DECODE" language="en_US">
<since>
<version>16.24.0</version>
<version>18.10.0</version>
<version>19.2.0</version>
</since>
<synopsis>
Returns the string value of a JSON object key from a string containing a
JSON array.
</synopsis>
<syntax>
<parameter name="varname" required="true">
<para>The name of the variable containing the JSON string to parse.</para>
</parameter>
<parameter name="item" required="true">
<para>The name of the key whose value to return.</para>
</parameter>
</syntax>
<description>
<para>The JSON_DECODE function retrieves the value of the given variable name
and parses it as JSON, returning the value at a specified key. If the key cannot
be found, an empty string is returned.</para>
</description>
<see-also>
<ref type="function">CURL</ref>
</see-also>
</function>
***/
AST_THREADSTORAGE(result_buf);
static int json_decode_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
{
struct ast_json *json, *jsonval;
AST_DECLARE_APP_ARGS(args,
AST_APP_ARG(varname);
AST_APP_ARG(key);
);
char *varsubst, *result2;
const char *result = NULL;
struct ast_str *str = ast_str_thread_get(&result_buf, 16);
AST_STANDARD_APP_ARGS(args, data);
if (ast_strlen_zero(args.varname)) {
ast_log(LOG_WARNING, "%s requires a variable name\n", cmd);
return -1;
}
if (ast_strlen_zero(args.key)) {
ast_log(LOG_WARNING, "%s requires a key\n", cmd);
return -1;
}
varsubst = ast_alloca(strlen(args.varname) + 4); /* +4 for ${} and null terminator */
if (!varsubst) {
ast_log(LOG_ERROR, "Failed to allocate string\n");
return -1;
}
sprintf(varsubst, "${%s}", args.varname); /* safe, because of the above allocation */
ast_str_substitute_variables(&str, 0, chan, varsubst);
if (ast_str_strlen(str) == 0) {
ast_debug(1, "Variable '%s' contains no data, nothing to search!\n", args.varname);
return -1; /* empty json string */
}
ast_debug(1, "Parsing JSON: %s\n", ast_str_buffer(str));
json = ast_json_load_str(str, NULL);
if (!json) {
ast_log(LOG_WARNING, "Failed to parse as JSON: %s\n", ast_str_buffer(str));
return -1;
}
jsonval = ast_json_object_get(json, args.key);
if (!jsonval) { /* no error or warning should be thrown */
ast_debug(1, "Could not find key '%s' in parsed JSON\n", args.key);
ast_json_free(json);
return -1;
}
switch(ast_json_typeof(jsonval)) {
int r;
case AST_JSON_STRING:
result = ast_json_string_get(jsonval);
snprintf(buf, len, "%s", result);
break;
case AST_JSON_INTEGER:
r = ast_json_integer_get(jsonval);
snprintf(buf, len, "%d", r); /* the snprintf below is mutually exclusive with this one */
break;
default:
result2 = ast_json_dump_string(jsonval);
snprintf(buf, len, "%s", result2);
ast_json_free(result2);
break;
}
ast_json_free(json);
return 0;
}
static struct ast_custom_function json_decode_function = {
.name = "JSON_DECODE",
.read = json_decode_read,
};
#ifdef TEST_FRAMEWORK
AST_TEST_DEFINE(test_JSON_DECODE)
{
int i, res = AST_TEST_PASS;
struct ast_channel *chan; /* dummy channel */
struct ast_str *str; /* fancy string for holding comparing value */
const char *test_strings[][5] = {
{"{\"city\": \"Anytown\", \"state\": \"USA\"}", "city", "Anytown"},
{"{\"city\": \"Anytown\", \"state\": \"USA\"}", "state", "USA"},
{"{\"city\": \"Anytown\", \"state\": \"USA\"}", "blah", ""},
{"{\"key1\": \"123\", \"key2\": \"456\"}", "key1", "123"},
{"{\"key1\": 123, \"key2\": 456}", "key1", "123"},
};
switch (cmd) {
case TEST_INIT:
info->name = "func_JSON_DECODE";
info->category = "/funcs/func_json/";
info->summary = "Test JSON_DECODE function";
info->description = "Verify JSON_DECODE behavior";
return AST_TEST_NOT_RUN;
case TEST_EXECUTE:
break;
}
if (!(chan = ast_dummy_channel_alloc())) {
ast_test_status_update(test, "Unable to allocate dummy channel\n");
return AST_TEST_FAIL;
}
if (!(str = ast_str_create(64))) {
ast_test_status_update(test, "Unable to allocate dynamic string buffer\n");
ast_channel_release(chan);
return AST_TEST_FAIL;
}
for (i = 0; i < ARRAY_LEN(test_strings); i++) {
char tmp[512], tmp2[512] = "";
struct ast_var_t *var = ast_var_assign("test_string", test_strings[i][0]);
if (!var) {
ast_test_status_update(test, "Unable to allocate variable\n");
ast_free(str);
ast_channel_release(chan);
return AST_TEST_FAIL;
}
AST_LIST_INSERT_HEAD(ast_channel_varshead(chan), var, entries);
snprintf(tmp, sizeof(tmp), "${JSON_DECODE(%s,%s)}", "test_string", test_strings[i][1]);
ast_str_substitute_variables(&str, 0, chan, tmp);
if (strcmp(test_strings[i][2], ast_str_buffer(str))) {
ast_test_status_update(test, "Format string '%s' substituted to '%s'. Expected '%s'.\n", test_strings[i][0], tmp2, test_strings[i][2]);
res = AST_TEST_FAIL;
}
}
ast_free(str);
ast_channel_release(chan);
return res;
}
#endif
static int unload_module(void)
{
int res;
AST_TEST_UNREGISTER(test_JSON_DECODE);
res = ast_custom_function_unregister(&json_decode_function);
return res;
}
static int load_module(void)
{
int res;
AST_TEST_REGISTER(test_JSON_DECODE);
res = ast_custom_function_register(&json_decode_function);
return res;
}
AST_MODULE_INFO_STANDARD_EXTENDED(ASTERISK_GPL_KEY, "JSON decoding function");