This commit fixes crashes in JSON_DECODE() for types null, true, false
and real numbers.
In addition it ensures that a path is not deeper than 32 levels.
Also allow root object to be an array.
Add unit tests for above cases.
(cherry picked from commit e6d5b8d8cf
)
420 lines
14 KiB
C
420 lines
14 KiB
C
/*
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* Asterisk -- An open source telephony toolkit.
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*
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* Copyright (C) 2021-2022, Naveen Albert
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*
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* See http://www.asterisk.org for more information about
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* the Asterisk project. Please do not directly contact
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* any of the maintainers of this project for assistance;
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* the project provides a web site, mailing lists and IRC
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* channels for your use.
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*
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* This program is free software, distributed under the terms of
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* the GNU General Public License Version 2. See the LICENSE file
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* at the top of the source tree.
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*/
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/*! \file
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*
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* \brief JSON parsing function
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*
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* \author Naveen Albert <asterisk@phreaknet.org>
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*
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* \ingroup functions
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*/
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/*** MODULEINFO
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<support_level>extended</support_level>
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***/
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#include "asterisk.h"
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#include "asterisk/module.h"
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#include "asterisk/channel.h"
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#include "asterisk/pbx.h"
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#include "asterisk/utils.h"
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#include "asterisk/test.h"
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#include "asterisk/app.h"
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#include "asterisk/conversions.h"
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/*** DOCUMENTATION
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<function name="JSON_DECODE" language="en_US">
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<since>
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<version>16.24.0</version>
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<version>18.10.0</version>
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<version>19.2.0</version>
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</since>
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<synopsis>
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Returns the string value of a JSON object key from a string containing a
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JSON array.
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</synopsis>
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<syntax>
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<parameter name="varname" required="true">
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<para>The name of the variable containing the JSON string to parse.</para>
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</parameter>
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<parameter name="item" required="true">
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<para>The name of the key whose value to return.</para>
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<para>Multiple keys can be listed separated by a hierarchy delimeter, which will recursively index into a nested JSON string to retrieve a specific subkey's value.</para>
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</parameter>
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<parameter name="separator" required="false">
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<para>A single character that delimits a key hierarchy for nested indexing. Default is a period (.)</para>
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<para>This value should not appear in the key or hierarchy of keys itself, except to delimit the hierarchy of keys.</para>
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</parameter>
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<parameter name="options" required="no">
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<optionlist>
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<option name="c">
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<para>For keys that reference a JSON array, return
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the number of items in the array.</para>
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<para>This option has no effect on any other type
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of value.</para>
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</option>
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</optionlist>
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</parameter>
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</syntax>
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<description>
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<para>The JSON_DECODE function retrieves the value of the given variable name
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and parses it as JSON, returning the value at a specified key. If the key cannot
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be found, an empty string is returned.</para>
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</description>
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<see-also>
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<ref type="function">CURL</ref>
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</see-also>
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</function>
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***/
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AST_THREADSTORAGE(result_buf);
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enum json_option_flags {
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OPT_COUNT = (1 << 0),
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};
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AST_APP_OPTIONS(json_options, {
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AST_APP_OPTION('c', OPT_COUNT),
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});
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#define MAX_JSON_STACK 32
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static int parse_node(char **key, char *currentkey, char *nestchar, int count, struct ast_json *json, char *buf, size_t len, int *depth)
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{
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const char *result = NULL;
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char *previouskey;
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struct ast_json *jsonval = json;
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/* Prevent a huge JSON string from blowing the stack. */
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(*depth)++;
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if (*depth > MAX_JSON_STACK) {
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ast_log(LOG_WARNING, "Max JSON stack (%d) exceeded\n", MAX_JSON_STACK);
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return -1;
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}
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snprintf(buf, len, "%s", ""); /* clear the buffer from previous round if necessary */
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if (!json) { /* no error or warning should be thrown */
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ast_debug(1, "Could not find key '%s' in parsed JSON\n", currentkey);
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return -1;
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}
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switch(ast_json_typeof(jsonval)) {
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unsigned long int size;
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int r;
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double d;
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case AST_JSON_STRING:
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result = ast_json_string_get(jsonval);
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ast_debug(1, "Got JSON string: %s\n", result);
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ast_copy_string(buf, result, len);
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break;
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case AST_JSON_INTEGER:
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r = ast_json_integer_get(jsonval);
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ast_debug(1, "Got JSON integer: %d\n", r);
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snprintf(buf, len, "%d", r); /* the snprintf below is mutually exclusive with this one */
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break;
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case AST_JSON_REAL:
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d = ast_json_real_get(jsonval);
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ast_debug(1, "Got JSON real: %.17g\n", d);
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snprintf(buf, len, "%.17g", d); /* the snprintf below is mutually exclusive with this one */
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break;
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case AST_JSON_ARRAY:
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ast_debug(1, "Got JSON array\n");
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previouskey = currentkey;
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currentkey = strsep(key, nestchar); /* retrieve the desired index */
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size = ast_json_array_size(jsonval);
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ast_debug(1, "Parsed JSON array of size %lu, key: %s\n", size, currentkey);
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if (!currentkey) { /* this is the end, so just dump the array */
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if (count) {
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ast_debug(1, "No key on which to index in the array, so returning count: %lu\n", size);
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snprintf(buf, len, "%lu", size);
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return 0;
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} else {
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char *result2 = ast_json_dump_string(jsonval);
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ast_debug(1, "No key on which to index in the array, so dumping '%s' array\n", previouskey);
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ast_copy_string(buf, result2, len);
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ast_json_free(result2);
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}
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} else if (ast_str_to_int(currentkey, &r) || r < 0) {
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ast_debug(1, "Requested index '%s' is not numeric or is invalid\n", currentkey);
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} else if (r >= size) {
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ast_debug(1, "Requested index '%d' does not exist in parsed array\n", r);
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} else {
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ast_debug(1, "Recursing on index %d in array\n", r);
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if (parse_node(key, currentkey, nestchar, count, ast_json_array_get(jsonval, r), buf, len, depth)) { /* recurse on this node */
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return -1;
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}
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}
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break;
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case AST_JSON_TRUE:
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case AST_JSON_FALSE:
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r = ast_json_is_true(jsonval);
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ast_debug(1, "Got JSON %s for key %s\n", r ? "true" : "false", currentkey);
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snprintf(buf, len, "%d", r); /* the snprintf below is mutually exclusive with this one */
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break;
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case AST_JSON_NULL:
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ast_debug(1, "Got JSON null for key %s\n", currentkey);
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break;
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case AST_JSON_OBJECT:
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ast_debug(1, "Got generic JSON object for key %s\n", currentkey);
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previouskey = currentkey;
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currentkey = strsep(key, nestchar); /* retrieve the desired index */
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if (!currentkey) { /* this is the end, so just dump the object */
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char *result2 = ast_json_dump_string(jsonval);
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ast_copy_string(buf, result2, len);
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ast_json_free(result2);
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} else {
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ast_debug(1, "Recursing on object (key was '%s' and is now '%s')\n", previouskey, currentkey);
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if (parse_node(key, currentkey, nestchar, count, ast_json_object_get(jsonval, currentkey), buf, len, depth)) { /* recurse on this node */
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return -1;
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}
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}
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break;
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default:
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ast_log(LOG_WARNING, "Got unsuported type %d\n", ast_json_typeof(jsonval));
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return -1;
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}
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return 0;
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}
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static int json_decode_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
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{
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int count = 0;
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struct ast_flags flags = {0};
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struct ast_json *json = NULL, *start = NULL;
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char *nestchar = "."; /* default delimeter for nesting key indexing is . */
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int index, res, depth = 0;
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AST_DECLARE_APP_ARGS(args,
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AST_APP_ARG(varname);
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AST_APP_ARG(key);
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AST_APP_ARG(nestchar);
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AST_APP_ARG(options);
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);
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char *varsubst, *key, *currentkey, *nextkey, *firstkey, *tmp;
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struct ast_str *str = ast_str_thread_get(&result_buf, 16);
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AST_STANDARD_APP_ARGS(args, data);
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if (!ast_strlen_zero(args.options)) {
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ast_app_parse_options(json_options, &flags, NULL, args.options);
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if (ast_test_flag(&flags, OPT_COUNT)) {
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count = 1;
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}
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}
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if (ast_strlen_zero(args.varname)) {
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ast_log(LOG_WARNING, "%s requires a variable name\n", cmd);
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return -1;
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}
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if (ast_strlen_zero(args.key)) {
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ast_log(LOG_WARNING, "%s requires a key\n", cmd);
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return -1;
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}
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key = ast_strdupa(args.key);
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if (!ast_strlen_zero(args.nestchar)) {
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int seplen = strlen(args.nestchar);
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if (seplen != 1) {
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ast_log(LOG_WARNING, "Nesting separator '%s' has length %d and is invalid (must be a single character)\n", args.nestchar, seplen);
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} else {
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nestchar = args.nestchar;
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}
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}
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varsubst = ast_alloca(strlen(args.varname) + 4); /* +4 for ${} and null terminator */
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if (!varsubst) {
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ast_log(LOG_ERROR, "Failed to allocate string\n");
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return -1;
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}
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sprintf(varsubst, "${%s}", args.varname); /* safe, because of the above allocation */
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ast_str_substitute_variables(&str, 0, chan, varsubst);
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ast_debug(1, "Parsing JSON using nesting delimeter '%s'\n", nestchar);
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if (ast_str_strlen(str) == 0) {
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ast_debug(1, "Variable '%s' contains no data, nothing to search!\n", args.varname);
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return -1; /* empty json string */
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}
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/* allow for multiple key nesting */
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currentkey = key;
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firstkey = ast_strdupa(currentkey);
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tmp = strstr(firstkey, nestchar);
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if (tmp) {
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*tmp = '\0';
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}
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/* parse a string as JSON */
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ast_debug(1, "Parsing JSON: %s (key: '%s')\n", ast_str_buffer(str), currentkey);
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if (ast_strlen_zero(currentkey)) {
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ast_debug(1, "Empty JSON key\n");
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return -1;
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}
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if (ast_str_strlen(str) == 0) {
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ast_debug(1, "JSON node '%s', contains no data, nothing to search!\n", currentkey);
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return -1; /* empty json string */
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}
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json = ast_json_load_str(str, NULL);
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if (!json) {
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ast_log(LOG_WARNING, "Failed to parse as JSON: %s\n", ast_str_buffer(str));
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return -1;
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}
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/* parse the JSON object, potentially recursively */
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nextkey = strsep(&key, nestchar);
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if (ast_json_is_object(json)) {
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start = ast_json_object_get(json, firstkey);
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} else {
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if (ast_str_to_int(currentkey, &index)) {
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ast_debug(1, "Requested index '%s' is not numeric or is invalid\n", currentkey);
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return -1;
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}
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start = ast_json_array_get(json, index);
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}
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res = parse_node(&key, nextkey, nestchar, count, start, buf, len, &depth);
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ast_json_unref(json);
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return res;
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}
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static struct ast_custom_function json_decode_function = {
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.name = "JSON_DECODE",
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.read = json_decode_read,
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};
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#ifdef TEST_FRAMEWORK
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AST_TEST_DEFINE(test_JSON_DECODE)
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{
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int i, res = AST_TEST_PASS;
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struct ast_channel *chan; /* dummy channel */
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struct ast_str *str; /* fancy string for holding comparing value */
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const char *test_strings[][6] = {
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{"{\"myboolean\": true, \"state\": \"USA\"}", "", "myboolean", "1"},
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{"{\"myboolean\": false, \"state\": \"USA\"}", "", "myboolean", "0"},
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{"{\"myreal\": 1E+2, \"state\": \"USA\"}", "", "myreal", "100"},
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{"{\"myreal\": 1.23, \"state\": \"USA\"}", "", "myreal", "1.23"},
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{"{\"myarray\": [[1]], \"state\": \"USA\"}", "", "myarray.0.0", "1"},
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{"{\"myarray\": [null], \"state\": \"USA\"}", "", "myarray.0", ""},
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{"{\"myarray\": [0, 1], \"state\": \"USA\"}", "", "myarray", "[0,1]"},
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{"[0, 1]", "", "", ""},
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{"[0, 1]", "", "0", "0"},
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{"[0, 1]", "", "foo", ""},
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{"{\"mynull\": null, \"state\": \"USA\"}", "", "mynull", ""},
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{"{\"city\": \"Anytown\", \"state\": \"USA\"}", "", "city", "Anytown"},
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{"{\"city\": \"Anytown\", \"state\": \"USA\"}", "", "state", "USA"},
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{"{\"city\": \"Anytown\", \"state\": \"USA\"}", "", "blah", ""},
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{"{\"key1\": \"123\", \"key2\": \"456\"}", "", "key1", "123"},
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{"{\"key1\": 123, \"key2\": 456}", "", "key1", "123"},
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{"{ \"path\": { \"to\": { \"elem\": \"someVar\" } } }", "/", "path/to/elem", "someVar"},
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{"{ \"path\": { \"to\": { \"elem\": \"someVar\" } } }", "", "path.to.elem2", ""},
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{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", "/", "path/to/arr/2", ""}, /* nonexistent index */
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{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", "/", "path/to/arr/-1", ""}, /* bogus index */
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{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", "/", "path/to/arr/test", ""}, /* bogus index */
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{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", "", "path.to.arr.test.test2.subkey", ""}, /* bogus index */
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{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", ",c", "path.to.arr", "2"}, /* test count */
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{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", "", "path.to.arr", "[\"item0\",\"item1\"]"},
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{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", ".", "path.to.arr.1", "item1"},
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{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", "/", "path/to/arr", "[\"item0\",\"item1\"]"},
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{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", "/", "path/to/arr/1", "item1"},
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{"{ \"path\": { \"to\": { \"arr\": [ {\"name\": \"John Smith\", \"phone\": \"123\"}, {\"name\": \"Jane Doe\", \"phone\": \"234\"} ] } } }", ",c", "path.to.arr.0.name", "John Smith"},
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{"{ \"path\": { \"to\": { \"arr\": [ {\"name\": 1, \"phone\": 123}, {\"name\": 2, \"phone\": 234} ] } } }", ",c", "path.to.arr.0.name", "1"},
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{"{ \"path\": { \"to\": { \"arr\": [ {\"name\": [ \"item11\", \"item12\" ], \"phone\": [ \"item13\", \"item14\" ]}, {\"name\": [ \"item15\", \"item16\" ], \"phone\": [ \"item17\", \"item18\" ]} ] } } }", ",c", "path.to.arr.0.name.1", "item12"},
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{"{ \"startId\": \"foobar\", \"abcd\": { \"id\": \"abcd\", \"type\": \"EXT\" }, \"bcde\": { \"id\": \"bcde\", \"type\": \"CONDITION\" }, \"defg\": { \"id\": \"defg\", \"type\": \"EXT\" }, \"efgh\": { \"id\": \"efgh\", \"type\": \"VOICEMAIL\" } }", "", "bcde", "{\"id\":\"bcde\",\"type\":\"CONDITION\"}"},
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};
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switch (cmd) {
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case TEST_INIT:
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info->name = "func_JSON_DECODE";
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info->category = "/funcs/func_json/";
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info->summary = "Test JSON_DECODE function";
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info->description = "Verify JSON_DECODE behavior";
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return AST_TEST_NOT_RUN;
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case TEST_EXECUTE:
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break;
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}
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if (!(chan = ast_dummy_channel_alloc())) {
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ast_test_status_update(test, "Unable to allocate dummy channel\n");
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return AST_TEST_FAIL;
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}
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if (!(str = ast_str_create(64))) {
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ast_test_status_update(test, "Unable to allocate dynamic string buffer\n");
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ast_channel_release(chan);
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return AST_TEST_FAIL;
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}
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for (i = 0; i < ARRAY_LEN(test_strings); i++) {
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char tmp[512];
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struct ast_var_t *var = ast_var_assign("test_string", test_strings[i][0]);
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if (!var) {
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ast_test_status_update(test, "Unable to allocate variable\n");
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ast_free(str);
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ast_channel_release(chan);
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return AST_TEST_FAIL;
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}
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AST_LIST_INSERT_HEAD(ast_channel_varshead(chan), var, entries);
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snprintf(tmp, sizeof(tmp), "${JSON_DECODE(%s,%s,%s)}", "test_string", test_strings[i][2], test_strings[i][1]);
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ast_str_substitute_variables(&str, 0, chan, tmp);
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if (strcmp(test_strings[i][3], ast_str_buffer(str))) {
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ast_test_status_update(test, "Format string '%s' substituted to '%s' (key: %s). Expected '%s'.\n", test_strings[i][0], ast_str_buffer(str), test_strings[i][2], test_strings[i][3]);
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res = AST_TEST_FAIL;
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}
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}
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ast_free(str);
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ast_channel_release(chan);
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return res;
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}
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#endif
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static int unload_module(void)
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{
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int res;
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#ifdef TEST_FRAMEWORK
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AST_TEST_UNREGISTER(test_JSON_DECODE);
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#endif
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res = ast_custom_function_unregister(&json_decode_function);
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return res;
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}
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static int load_module(void)
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{
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int res;
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#ifdef TEST_FRAMEWORK
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AST_TEST_REGISTER(test_JSON_DECODE);
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#endif
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res = ast_custom_function_register(&json_decode_function);
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return res;
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}
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AST_MODULE_INFO_STANDARD_EXTENDED(ASTERISK_GPL_KEY, "JSON decoding function");
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