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