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