Asterisk
/
asterisk
mirror of https://github.com/asterisk/asterisk
1
0
Fork 0
Code Issues Releases Wiki Activity

func_json: Enhance parsing capabilities of JSON_DECODE

Browse Source 
Adds support for arrays to JSON_DECODE by allowing the
user to print out entire arrays or index a particular
key or print the number of keys in a JSON array.

Additionally, adds support for recursively iterating a
JSON tree in a single function call, making it easier
to parse JSON results with multiple levels. A maximum
depth is imposed to prevent potentially blowing
the stack.

Also fixes a bug with the unit tests causing an empty
string to be printed instead of the actual test result.

ASTERISK-29913 #close

Change-Id: I603940b216a3911b498fc6583b18934011ef5d5b
18.17
Naveen Albert 3 years ago committed by George Joseph
parent ec0ca7dcbc
commit 7b9ef96173
2 changed files with 197 additions and 40 deletions
Show Stats Download Patch File Download Diff File

5
doc/CHANGES-staging/func_json_additions.txt
Unescape View File

@ -0,0 +1,5 @@
Subject: func_json
Additional parsing capabilities have been added to the
JSON_DECODE function, including support for arrays
and recursive indexing.

232
funcs/func_json.c
Unescape View File

@ -1,7 +1,7 @@
/*
* Asterisk -- An open source telephony toolkit.
*
* Copyright (C) 2021, Naveen Albert
* Copyright (C) 2021-2022, Naveen Albert
*
* See http://www.asterisk.org for more information about
* the Asterisk project. Please do not directly contact
@ -54,6 +54,21 @@
</parameter>
<parameter name="item" required="true">
<para>The name of the key whose value to return.</para>
<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>
</parameter>
<parameter name="separator" required="false">
<para>A single character that delimits a key hierarchy for nested indexing. Default is a period (.)</para>
<para>This value should not appear in the key or hierarchy of keys itself, except to delimit the hierarchy of keys.</para>
</parameter>
<parameter name="options" required="no">
<optionlist>
<option name="c">
<para>For keys that reference a JSON array, return
the number of items in the array.</para>
<para>This option has no effect on any other type
of value.</para>
</option>
</optionlist>
</parameter>
</syntax>
<description>
@ -69,19 +84,131 @@
AST_THREADSTORAGE(result_buf);
enum json_option_flags {
OPT_COUNT = (1 << 0),
};
AST_APP_OPTIONS(json_options, {
AST_APP_OPTION('c', OPT_COUNT),
});
#define MAX_JSON_STACK 32
static int parse_node(char **key, char *currentkey, char *nestchar, int count, struct ast_json *json, char *buf, size_t len, int *depth)
{
const char *result = NULL;
char *previouskey;
struct ast_json *jsonval = json;
/* Prevent a huge JSON string from blowing the stack. */
if (*depth > MAX_JSON_STACK) {
ast_log(LOG_WARNING, "Max JSON stack (%d) exceeded\n", MAX_JSON_STACK);
return -1;
}
snprintf(buf, len, "%s", ""); /* clear the buffer from previous round if necessary */
if (!json) { /* no error or warning should be thrown */
ast_debug(1, "Could not find key '%s' in parsed JSON\n", currentkey);
return -1;
}
switch(ast_json_typeof(jsonval)) {
unsigned long int size;
int r;
case AST_JSON_STRING:
result = ast_json_string_get(jsonval);
ast_debug(1, "Got JSON string: %s\n", result);
ast_copy_string(buf, result, len);
break;
case AST_JSON_INTEGER:
r = ast_json_integer_get(jsonval);
ast_debug(1, "Got JSON integer: %d\n", r);
snprintf(buf, len, "%d", r); /* the snprintf below is mutually exclusive with this one */
break;
case AST_JSON_ARRAY:
ast_debug(1, "Got JSON array\n");
previouskey = currentkey;
currentkey = strsep(key, nestchar); /* retrieve the desired index */
size = ast_json_array_size(jsonval);
ast_debug(1, "Parsed JSON array of size %lu, key: %s\n", size, currentkey);
if (!currentkey) { /* this is the end, so just dump the array */
if (count) {
ast_debug(1, "No key on which to index in the array, so returning count: %lu\n", size);
snprintf(buf, len, "%lu", size);
return 0;
} else {
char *result2 = ast_json_dump_string(jsonval);
ast_debug(1, "No key on which to index in the array, so dumping '%s' array\n", previouskey);
ast_copy_string(buf, result2, len);
ast_json_free(result2);
}
} else if (ast_str_to_int(currentkey, &r) || r < 0) {
ast_debug(1, "Requested index '%s' is not numeric or is invalid\n", currentkey);
} else if (r >= size) {
ast_debug(1, "Requested index '%d' does not exist in parsed array\n", r);
} else {
struct ast_json *json2 = ast_json_array_get(jsonval, r);
if (!json2) {
ast_debug(1, "Array index %d contains empty item\n", r);
return -1;
}
previouskey = currentkey;
currentkey = strsep(key, nestchar); /* get the next subkey */
ast_debug(1, "Recursing on index %d in array (key was '%s' and is now '%s')\n", r, previouskey, currentkey);
/* json2 is a borrowed ref. That's fine, since json won't get freed until recursing is over */
/* If there are keys remaining, then parse the next object we can get. Otherwise, just dump the child */
if (parse_node(key, currentkey, nestchar, count, currentkey ? ast_json_object_get(json2, currentkey) : json2, buf, len, depth)) { /* recurse on this node */
return -1;
}
}
break;
case AST_JSON_OBJECT:
default:
ast_debug(1, "Got generic JSON object for key %s\n", currentkey);
if (!currentkey) { /* this is the end, so just dump the object */
char *result2 = ast_json_dump_string(jsonval);
ast_copy_string(buf, result2, len);
ast_json_free(result2);
} else {
previouskey = currentkey;
currentkey = strsep(key, nestchar); /* retrieve the desired index */
ast_debug(1, "Recursing on object (key was '%s' and is now '%s')\n", previouskey, currentkey);
if (parse_node(key, currentkey, nestchar, count, ast_json_object_get(jsonval, currentkey), buf, len, depth)) { /* recurse on this node */
return -1;
}
}
break;
}
return 0;
}
static int json_decode_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
{
struct ast_json *json, *jsonval;
int count = 0;
struct ast_flags flags = {0};
struct ast_json *json = NULL;
char *nestchar = "."; /* default delimeter for nesting key indexing is . */
int res, depth = 0;
AST_DECLARE_APP_ARGS(args,
AST_APP_ARG(varname);
AST_APP_ARG(key);
AST_APP_ARG(nestchar);
AST_APP_ARG(options);
);
char *varsubst, *result2;
const char *result = NULL;
char *varsubst, *key, *currentkey, *nextkey, *firstkey, *tmp;
struct ast_str *str = ast_str_thread_get(&result_buf, 16);
AST_STANDARD_APP_ARGS(args, data);
if (!ast_strlen_zero(args.options)) {
ast_app_parse_options(json_options, &flags, NULL, args.options);
if (ast_test_flag(&flags, OPT_COUNT)) {
count = 1;
}
}
if (ast_strlen_zero(args.varname)) {
ast_log(LOG_WARNING, "%s requires a variable name\n", cmd);
return -1;
@ -90,6 +217,15 @@ static int json_decode_read(struct ast_channel *chan, const char *cmd, char *dat
ast_log(LOG_WARNING, "%s requires a key\n", cmd);
return -1;
}
key = ast_strdupa(args.key);
if (!ast_strlen_zero(args.nestchar)) {
int seplen = strlen(args.nestchar);
if (seplen != 1) {
ast_log(LOG_WARNING, "Nesting separator '%s' has length %d and is invalid (must be a single character)\n", args.nestchar, seplen);
} else {
nestchar = args.nestchar;
}
}
varsubst = ast_alloca(strlen(args.varname) + 4); /* +4 for ${} and null terminator */
if (!varsubst) {
@ -98,45 +234,43 @@ static int json_decode_read(struct ast_channel *chan, const char *cmd, char *dat
}
sprintf(varsubst, "${%s}", args.varname); /* safe, because of the above allocation */
ast_str_substitute_variables(&str, 0, chan, varsubst);
ast_debug(1, "Parsing JSON using nesting delimeter '%s'\n", nestchar);
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));
/* allow for multiple key nesting */
currentkey = key;
firstkey = ast_strdupa(currentkey);
tmp = strstr(firstkey, nestchar);
if (tmp) {
*tmp = '\0';
}
/* parse a string as JSON */
ast_debug(1, "Parsing JSON: %s (key: '%s')\n", ast_str_buffer(str), currentkey);
if (ast_strlen_zero(currentkey)) {
ast_debug(1, "Empty JSON key\n");
return -1;
}
if (ast_str_strlen(str) == 0) {
ast_debug(1, "JSON node '%s', contains no data, nothing to search!\n", currentkey);
return -1; /* empty json string */
}
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_unref(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;
}
/* parse the JSON object, potentially recursively */
nextkey = strsep(&key, nestchar);
res = parse_node(&key, nextkey, nestchar, count, ast_json_object_get(json, firstkey), buf, len, &depth);
ast_json_unref(json);
return 0;
return res;
}
static struct ast_custom_function json_decode_function = {
@ -151,12 +285,26 @@ AST_TEST_DEFINE(test_JSON_DECODE)
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"},
const char *test_strings[][6] = {
{"{\"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"},
{"{ \"path\": { \"to\": { \"elem\": \"someVar\" } } }", "/", "path/to/elem", "someVar"},
{"{ \"path\": { \"to\": { \"elem\": \"someVar\" } } }", "", "path.to.elem2", ""},
{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", "/", "path/to/arr/2", ""}, /* nonexistent index */
{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", "/", "path/to/arr/-1", ""}, /* bogus index */
{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", "/", "path/to/arr/test", ""}, /* bogus index */
{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", "", "path.to.arr.test.test2.subkey", ""}, /* bogus index */
{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", ",c", "path.to.arr", "2"}, /* test count */
{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", "", "path.to.arr", "[\"item0\",\"item1\"]"},
{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", ".", "path.to.arr.1", "item1"},
{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", "/", "path/to/arr", "[\"item0\",\"item1\"]"},
{"{ \"path\": { \"to\": { \"arr\": [ \"item0\", \"item1\" ] } } }", "/", "path/to/arr/1", "item1"},
{"{ \"path\": { \"to\": { \"arr\": [ {\"name\": \"John Smith\", \"phone\": \"123\"}, {\"name\": \"Jane Doe\", \"phone\": \"234\"} ] } } }", ",c", "path.to.arr.0.name", "John Smith"},
{"{ \"path\": { \"to\": { \"arr\": [ {\"name\": 1, \"phone\": 123}, {\"name\": 2, \"phone\": 234} ] } } }", ",c", "path.to.arr.0.name", "1"},
{"{ \"path\": { \"to\": { \"arr\": [ {\"name\": [ \"item11\", \"item12\" ], \"phone\": [ \"item13\", \"item14\" ]}, {\"name\": [ \"item15\", \"item16\" ], \"phone\": [ \"item17\", \"item18\" ]} ] } } }", ",c", "path.to.arr.0.name.1", "item12"},
};
switch (cmd) {
@ -182,7 +330,7 @@ AST_TEST_DEFINE(test_JSON_DECODE)
}
for (i = 0; i < ARRAY_LEN(test_strings); i++) {
char tmp[512], tmp2[512] = "";
char tmp[512];
struct ast_var_t *var = ast_var_assign("test_string", test_strings[i][0]);
if (!var) {
@ -194,11 +342,11 @@ AST_TEST_DEFINE(test_JSON_DECODE)
AST_LIST_INSERT_HEAD(ast_channel_varshead(chan), var, entries);
snprintf(tmp, sizeof(tmp), "${JSON_DECODE(%s,%s)}", "test_string", test_strings[i][1]);
snprintf(tmp, sizeof(tmp), "${JSON_DECODE(%s,%s,%s)}", "test_string", test_strings[i][2], 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]);
if (strcmp(test_strings[i][3], ast_str_buffer(str))) {
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]);
res = AST_TEST_FAIL;
}
}
@ -214,7 +362,9 @@ static int unload_module(void)
{
int res;
#ifdef TEST_FRAMEWORK
AST_TEST_UNREGISTER(test_JSON_DECODE);
#endif
res = ast_custom_function_unregister(&json_decode_function);
return res;
@ -224,7 +374,9 @@ static int load_module(void)
{
int res;
#ifdef TEST_FRAMEWORK
AST_TEST_REGISTER(test_JSON_DECODE);
#endif
res = ast_custom_function_register(&json_decode_function);
return res;

Write Preview
Loading…
Cancel
Save