1 /*
2  * JavaScript Object Notation (JSON) parser (RFC7159)
3  * Copyright (c) 2017, Qualcomm Atheros, Inc.
4  *
5  * This software may be distributed under the terms of the BSD license.
6  * See README for more details.
7  */
8 
9 #include "includes.h"
10 
11 #include "common.h"
12 #include "base64.h"
13 #include "json.h"
14 
15 #define JSON_MAX_DEPTH 10
16 #define JSON_MAX_TOKENS 500
17 
18 
19 void json_escape_string(char *txt, size_t maxlen, const char *data, size_t len)
20 {
21 	char *end = txt + maxlen;
22 	size_t i;
23 
24 	for (i = 0; i < len; i++) {
25 		if (txt + 4 >= end)
26 			break;
27 
28 		switch (data[i]) {
29 		case '\"':
30 			*txt++ = '\\';
31 			*txt++ = '\"';
32 			break;
33 		case '\\':
34 			*txt++ = '\\';
35 			*txt++ = '\\';
36 			break;
37 		case '\n':
38 			*txt++ = '\\';
39 			*txt++ = 'n';
40 			break;
41 		case '\r':
42 			*txt++ = '\\';
43 			*txt++ = 'r';
44 			break;
45 		case '\t':
46 			*txt++ = '\\';
47 			*txt++ = 't';
48 			break;
49 		default:
50 			if (data[i] >= 32 && data[i] <= 126) {
51 				*txt++ = data[i];
52 			} else {
53 				txt += os_snprintf(txt, end - txt, "\\u%04x",
54 						   data[i]);
55 			}
56 			break;
57 		}
58 	}
59 
60 	*txt = '\0';
61 }
62 
63 
64 static char * json_parse_string(const char **json_pos, const char *end)
65 {
66 	const char *pos = *json_pos;
67 	char *str, *spos, *s_end;
68 	size_t max_len, buf_len;
69 	u8 bin[2];
70 
71 	pos++; /* skip starting quote */
72 
73 	max_len = end - pos + 1;
74 	buf_len = max_len > 10 ? 10 : max_len;
75 	str = os_malloc(buf_len);
76 	if (!str)
77 		return NULL;
78 	spos = str;
79 	s_end = str + buf_len;
80 
81 	for (; pos < end; pos++) {
82 		if (buf_len < max_len && s_end - spos < 3) {
83 			char *tmp;
84 			int idx;
85 
86 			idx = spos - str;
87 			buf_len *= 2;
88 			if (buf_len > max_len)
89 				buf_len = max_len;
90 			tmp = os_realloc(str, buf_len);
91 			if (!tmp)
92 				goto fail;
93 			str = tmp;
94 			spos = str + idx;
95 			s_end = str + buf_len;
96 		}
97 
98 		switch (*pos) {
99 		case '\"': /* end string */
100 			*spos = '\0';
101 			/* caller will move to the next position */
102 			*json_pos = pos;
103 			return str;
104 		case '\\':
105 			pos++;
106 			if (pos >= end) {
107 				wpa_printf(MSG_DEBUG,
108 					   "JSON: Truncated \\ escape");
109 				goto fail;
110 			}
111 			switch (*pos) {
112 			case '"':
113 			case '\\':
114 			case '/':
115 				*spos++ = *pos;
116 				break;
117 			case 'n':
118 				*spos++ = '\n';
119 				break;
120 			case 'r':
121 				*spos++ = '\r';
122 				break;
123 			case 't':
124 				*spos++ = '\t';
125 				break;
126 			case 'u':
127 				if (end - pos < 5 ||
128 				    hexstr2bin(pos + 1, bin, 2) < 0 ||
129 				    bin[1] == 0x00) {
130 					wpa_printf(MSG_DEBUG,
131 						   "JSON: Invalid \\u escape");
132 					goto fail;
133 				}
134 				if (bin[0] == 0x00) {
135 					*spos++ = bin[1];
136 				} else {
137 					*spos++ = bin[0];
138 					*spos++ = bin[1];
139 				}
140 				pos += 4;
141 				break;
142 			default:
143 				wpa_printf(MSG_DEBUG,
144 					   "JSON: Unknown escape '%c'", *pos);
145 				goto fail;
146 			}
147 			break;
148 		default:
149 			*spos++ = *pos;
150 			break;
151 		}
152 	}
153 
154 fail:
155 	os_free(str);
156 	return NULL;
157 }
158 
159 
160 static int json_parse_number(const char **json_pos, const char *end,
161 			     int *ret_val)
162 {
163 	const char *pos = *json_pos;
164 	size_t len;
165 	char *str;
166 
167 	for (; pos < end; pos++) {
168 		if (*pos != '-' && (*pos < '0' || *pos > '9')) {
169 			pos--;
170 			break;
171 		}
172 	}
173 	if (pos == end)
174 		pos--;
175 	if (pos < *json_pos)
176 		return -1;
177 	len = pos - *json_pos + 1;
178 	str = os_malloc(len + 1);
179 	if (!str)
180 		return -1;
181 	os_memcpy(str, *json_pos, len);
182 	str[len] = '\0';
183 
184 	*ret_val = atoi(str);
185 	os_free(str);
186 	*json_pos = pos;
187 	return 0;
188 }
189 
190 
191 static int json_check_tree_state(struct json_token *token)
192 {
193 	if (!token)
194 		return 0;
195 	if (json_check_tree_state(token->child) < 0 ||
196 	    json_check_tree_state(token->sibling) < 0)
197 		return -1;
198 	if (token->state != JSON_COMPLETED) {
199 		wpa_printf(MSG_DEBUG,
200 			   "JSON: Unexpected token state %d (name=%s type=%d)",
201 			   token->state, token->name ? token->name : "N/A",
202 			   token->type);
203 		return -1;
204 	}
205 	return 0;
206 }
207 
208 
209 static struct json_token * json_alloc_token(unsigned int *tokens)
210 {
211 	(*tokens)++;
212 	if (*tokens > JSON_MAX_TOKENS) {
213 		wpa_printf(MSG_DEBUG, "JSON: Maximum token limit exceeded");
214 		return NULL;
215 	}
216 	return os_zalloc(sizeof(struct json_token));
217 }
218 
219 
220 struct json_token * json_parse(const char *data, size_t data_len)
221 {
222 	struct json_token *root = NULL, *curr_token = NULL, *token = NULL;
223 	const char *pos, *end;
224 	char *str;
225 	int num;
226 	unsigned int depth = 0;
227 	unsigned int tokens = 0;
228 
229 	pos = data;
230 	end = data + data_len;
231 
232 	for (; pos < end; pos++) {
233 		switch (*pos) {
234 		case '[': /* start array */
235 		case '{': /* start object */
236 			if (!curr_token) {
237 				token = json_alloc_token(&tokens);
238 				if (!token)
239 					goto fail;
240 				if (!root)
241 					root = token;
242 			} else if (curr_token->state == JSON_WAITING_VALUE) {
243 				token = curr_token;
244 			} else if (curr_token->parent &&
245 				   curr_token->parent->type == JSON_ARRAY &&
246 				   curr_token->parent->state == JSON_STARTED &&
247 				   curr_token->state == JSON_EMPTY) {
248 				token = curr_token;
249 			} else {
250 				wpa_printf(MSG_DEBUG,
251 					   "JSON: Invalid state for start array/object");
252 				goto fail;
253 			}
254 			depth++;
255 			if (depth > JSON_MAX_DEPTH) {
256 				wpa_printf(MSG_DEBUG,
257 					   "JSON: Max depth exceeded");
258 				goto fail;
259 			}
260 			token->type = *pos == '[' ? JSON_ARRAY : JSON_OBJECT;
261 			token->state = JSON_STARTED;
262 			token->child = json_alloc_token(&tokens);
263 			if (!token->child)
264 				goto fail;
265 			curr_token = token->child;
266 			curr_token->parent = token;
267 			curr_token->state = JSON_EMPTY;
268 			break;
269 		case ']': /* end array */
270 		case '}': /* end object */
271 			if (!curr_token || !curr_token->parent ||
272 			    curr_token->parent->state != JSON_STARTED) {
273 				wpa_printf(MSG_DEBUG,
274 					   "JSON: Invalid state for end array/object");
275 				goto fail;
276 			}
277 			depth--;
278 			curr_token = curr_token->parent;
279 			if ((*pos == ']' &&
280 			     curr_token->type != JSON_ARRAY) ||
281 			    (*pos == '}' &&
282 			     curr_token->type != JSON_OBJECT)) {
283 				wpa_printf(MSG_DEBUG,
284 					   "JSON: Array/Object mismatch");
285 				goto fail;
286 			}
287 			if (curr_token->child->state == JSON_EMPTY &&
288 			    !curr_token->child->child &&
289 			    !curr_token->child->sibling) {
290 				/* Remove pending child token since the
291 				 * array/object was empty. */
292 				json_free(curr_token->child);
293 				curr_token->child = NULL;
294 			}
295 			curr_token->state = JSON_COMPLETED;
296 			break;
297 		case '\"': /* string */
298 			str = json_parse_string(&pos, end);
299 			if (!str)
300 				goto fail;
301 			if (!curr_token) {
302 				token = json_alloc_token(&tokens);
303 				if (!token)
304 					goto fail;
305 				token->type = JSON_STRING;
306 				token->string = str;
307 				token->state = JSON_COMPLETED;
308 			} else if (curr_token->parent &&
309 				   curr_token->parent->type == JSON_ARRAY &&
310 				   curr_token->parent->state == JSON_STARTED &&
311 				   curr_token->state == JSON_EMPTY) {
312 				curr_token->string = str;
313 				curr_token->state = JSON_COMPLETED;
314 				curr_token->type = JSON_STRING;
315 				wpa_printf(MSG_MSGDUMP,
316 					   "JSON: String value: '%s'",
317 					   curr_token->string);
318 			} else if (curr_token->state == JSON_EMPTY) {
319 				curr_token->type = JSON_VALUE;
320 				curr_token->name = str;
321 				curr_token->state = JSON_STARTED;
322 			} else if (curr_token->state == JSON_WAITING_VALUE) {
323 				curr_token->string = str;
324 				curr_token->state = JSON_COMPLETED;
325 				curr_token->type = JSON_STRING;
326 				wpa_printf(MSG_MSGDUMP,
327 					   "JSON: String value: '%s' = '%s'",
328 					   curr_token->name,
329 					   curr_token->string);
330 			} else {
331 				wpa_printf(MSG_DEBUG,
332 					   "JSON: Invalid state for a string");
333 				os_free(str);
334 				goto fail;
335 			}
336 			break;
337 		case ' ':
338 		case '\t':
339 		case '\r':
340 		case '\n':
341 			/* ignore whitespace */
342 			break;
343 		case ':': /* name/value separator */
344 			if (!curr_token || curr_token->state != JSON_STARTED)
345 				goto fail;
346 			curr_token->state = JSON_WAITING_VALUE;
347 			break;
348 		case ',': /* member separator */
349 			if (!curr_token)
350 				goto fail;
351 			curr_token->sibling = json_alloc_token(&tokens);
352 			if (!curr_token->sibling)
353 				goto fail;
354 			curr_token->sibling->parent = curr_token->parent;
355 			curr_token = curr_token->sibling;
356 			curr_token->state = JSON_EMPTY;
357 			break;
358 		case 't': /* true */
359 		case 'f': /* false */
360 		case 'n': /* null */
361 			if (!((end - pos >= 4 &&
362 			       os_strncmp(pos, "true", 4) == 0) ||
363 			      (end - pos >= 5 &&
364 			       os_strncmp(pos, "false", 5) == 0) ||
365 			      (end - pos >= 4 &&
366 			       os_strncmp(pos, "null", 4) == 0))) {
367 				wpa_printf(MSG_DEBUG,
368 					   "JSON: Invalid literal name");
369 				goto fail;
370 			}
371 			if (!curr_token) {
372 				token = json_alloc_token(&tokens);
373 				if (!token)
374 					goto fail;
375 				curr_token = token;
376 			} else if (curr_token->state == JSON_WAITING_VALUE) {
377 				wpa_printf(MSG_MSGDUMP,
378 					   "JSON: Literal name: '%s' = %c",
379 					   curr_token->name, *pos);
380 			} else if (curr_token->parent &&
381 				   curr_token->parent->type == JSON_ARRAY &&
382 				   curr_token->parent->state == JSON_STARTED &&
383 				   curr_token->state == JSON_EMPTY) {
384 				wpa_printf(MSG_MSGDUMP,
385 					   "JSON: Literal name: %c", *pos);
386 			} else {
387 				wpa_printf(MSG_DEBUG,
388 					   "JSON: Invalid state for a literal name");
389 				goto fail;
390 			}
391 			switch (*pos) {
392 			case 't':
393 				curr_token->type = JSON_BOOLEAN;
394 				curr_token->number = 1;
395 				pos += 3;
396 				break;
397 			case 'f':
398 				curr_token->type = JSON_BOOLEAN;
399 				curr_token->number = 0;
400 				pos += 4;
401 				break;
402 			case 'n':
403 				curr_token->type = JSON_NULL;
404 				pos += 3;
405 				break;
406 			}
407 			curr_token->state = JSON_COMPLETED;
408 			break;
409 		case '-':
410 		case '0':
411 		case '1':
412 		case '2':
413 		case '3':
414 		case '4':
415 		case '5':
416 		case '6':
417 		case '7':
418 		case '8':
419 		case '9':
420 			/* number */
421 			if (json_parse_number(&pos, end, &num) < 0)
422 				goto fail;
423 			if (!curr_token) {
424 				token = json_alloc_token(&tokens);
425 				if (!token)
426 					goto fail;
427 				token->type = JSON_NUMBER;
428 				token->number = num;
429 				token->state = JSON_COMPLETED;
430 			} else if (curr_token->state == JSON_WAITING_VALUE) {
431 				curr_token->number = num;
432 				curr_token->state = JSON_COMPLETED;
433 				curr_token->type = JSON_NUMBER;
434 				wpa_printf(MSG_MSGDUMP,
435 					   "JSON: Number value: '%s' = '%d'",
436 					   curr_token->name,
437 					   curr_token->number);
438 			} else if (curr_token->parent &&
439 				   curr_token->parent->type == JSON_ARRAY &&
440 				   curr_token->parent->state == JSON_STARTED &&
441 				   curr_token->state == JSON_EMPTY) {
442 				curr_token->number = num;
443 				curr_token->state = JSON_COMPLETED;
444 				curr_token->type = JSON_NUMBER;
445 				wpa_printf(MSG_MSGDUMP,
446 					   "JSON: Number value: %d",
447 					   curr_token->number);
448 			} else {
449 				wpa_printf(MSG_DEBUG,
450 					   "JSON: Invalid state for a number");
451 				goto fail;
452 			}
453 			break;
454 		default:
455 			wpa_printf(MSG_DEBUG,
456 				   "JSON: Unexpected JSON character: %c", *pos);
457 			goto fail;
458 		}
459 
460 		if (!root)
461 			root = token;
462 		if (!curr_token)
463 			curr_token = token;
464 	}
465 
466 	if (json_check_tree_state(root) < 0) {
467 		wpa_printf(MSG_DEBUG, "JSON: Incomplete token in the tree");
468 		goto fail;
469 	}
470 
471 	return root;
472 fail:
473 	wpa_printf(MSG_DEBUG, "JSON: Parsing failed");
474 	json_free(root);
475 	return NULL;
476 }
477 
478 
479 void json_free(struct json_token *json)
480 {
481 	if (!json)
482 		return;
483 	json_free(json->child);
484 	json_free(json->sibling);
485 	os_free(json->name);
486 	os_free(json->string);
487 	os_free(json);
488 }
489 
490 
491 struct json_token * json_get_member(struct json_token *json, const char *name)
492 {
493 	struct json_token *token, *ret = NULL;
494 
495 	if (!json || json->type != JSON_OBJECT)
496 		return NULL;
497 	/* Return last matching entry */
498 	for (token = json->child; token; token = token->sibling) {
499 		if (token->name && os_strcmp(token->name, name) == 0)
500 			ret = token;
501 	}
502 	return ret;
503 }
504 
505 
506 struct wpabuf * json_get_member_base64url(struct json_token *json,
507 					  const char *name)
508 {
509 	struct json_token *token;
510 	unsigned char *buf;
511 	size_t buflen;
512 	struct wpabuf *ret;
513 
514 	token = json_get_member(json, name);
515 	if (!token || token->type != JSON_STRING)
516 		return NULL;
517 	buf = base64_url_decode((const unsigned char *) token->string,
518 				os_strlen(token->string), &buflen);
519 	if (!buf)
520 		return NULL;
521 	ret = wpabuf_alloc_ext_data(buf, buflen);
522 	if (!ret)
523 		os_free(buf);
524 
525 	return ret;
526 }
527 
528 
529 static const char * json_type_str(enum json_type type)
530 {
531 	switch (type) {
532 	case JSON_VALUE:
533 		return "VALUE";
534 	case JSON_OBJECT:
535 		return "OBJECT";
536 	case JSON_ARRAY:
537 		return "ARRAY";
538 	case JSON_STRING:
539 		return "STRING";
540 	case JSON_NUMBER:
541 		return "NUMBER";
542 	case JSON_BOOLEAN:
543 		return "BOOLEAN";
544 	case JSON_NULL:
545 		return "NULL";
546 	}
547 	return "??";
548 }
549 
550 
551 static void json_print_token(struct json_token *token, int depth,
552 			     char *buf, size_t buflen)
553 {
554 	size_t len;
555 	int ret;
556 
557 	if (!token)
558 		return;
559 	len = os_strlen(buf);
560 	ret = os_snprintf(buf + len, buflen - len, "[%d:%s:%s]",
561 			  depth, json_type_str(token->type),
562 			  token->name ? token->name : "");
563 	if (os_snprintf_error(buflen - len, ret)) {
564 		buf[len] = '\0';
565 		return;
566 	}
567 	json_print_token(token->child, depth + 1, buf, buflen);
568 	json_print_token(token->sibling, depth, buf, buflen);
569 }
570 
571 
572 void json_print_tree(struct json_token *root, char *buf, size_t buflen)
573 {
574 	buf[0] = '\0';
575 	json_print_token(root, 1, buf, buflen);
576 }
577