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
json_escape_string(char * txt,size_t maxlen,const char * data,size_t len)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
json_parse_string(const char ** json_pos,const char * end)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
json_parse_number(const char ** json_pos,const char * end,int * ret_val)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
json_check_tree_state(struct json_token * token)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
json_alloc_token(unsigned int * tokens)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
json_parse(const char * data,size_t data_len)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
json_free(struct json_token * json)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
json_get_member(struct json_token * json,const char * name)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
json_get_member_base64url(struct json_token * json,const char * name)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
json_type_str(enum json_type type)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
json_print_token(struct json_token * token,int depth,char * buf,size_t buflen)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
json_print_tree(struct json_token * root,char * buf,size_t buflen)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