1 /* 2 * wire2host.c 3 * 4 * conversion routines from the wire to the host 5 * format. 6 * This will usually just a re-ordering of the 7 * data (as we store it in network format) 8 * 9 * a Net::DNS like library for C 10 * 11 * (c) NLnet Labs, 2004-2006 12 * 13 * See the file LICENSE for the license 14 */ 15 16 17 #include <ldns/config.h> 18 19 #include <ldns/ldns.h> 20 /*#include <ldns/wire2host.h>*/ 21 22 #include <strings.h> 23 #include <limits.h> 24 25 26 27 /* 28 * Set of macro's to deal with the dns message header as specified 29 * in RFC1035 in portable way. 30 * 31 */ 32 33 /* 34 * 35 * 1 1 1 1 1 1 36 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 37 * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ 38 * | ID | 39 * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ 40 * |QR| Opcode |AA|TC|RD|RA| Z|AD|CD| RCODE | 41 * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ 42 * | QDCOUNT | 43 * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ 44 * | ANCOUNT | 45 * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ 46 * | NSCOUNT | 47 * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ 48 * | ARCOUNT | 49 * +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ 50 * 51 */ 52 53 54 /* allocates memory to *dname! */ 55 ldns_status 56 ldns_wire2dname(ldns_rdf **dname, const uint8_t *wire, size_t max, size_t *pos) 57 { 58 uint8_t label_size; 59 uint16_t pointer_target; 60 uint8_t pointer_target_buf[2]; 61 size_t dname_pos = 0; 62 size_t uncompressed_length = 0; 63 size_t compression_pos = 0; 64 uint8_t tmp_dname[LDNS_MAX_DOMAINLEN]; 65 unsigned int pointer_count = 0; 66 67 if (pos == NULL) { 68 return LDNS_STATUS_WIRE_RDATA_ERR; 69 } 70 if (*pos >= max) { 71 return LDNS_STATUS_PACKET_OVERFLOW; 72 } 73 label_size = wire[*pos]; 74 while (label_size > 0) { 75 /* compression */ 76 while (label_size >= 192) { 77 if (compression_pos == 0) { 78 compression_pos = *pos + 2; 79 } 80 81 pointer_count++; 82 83 /* remove first two bits */ 84 if (*pos + 2 > max) { 85 return LDNS_STATUS_PACKET_OVERFLOW; 86 } 87 pointer_target_buf[0] = wire[*pos] & 63; 88 pointer_target_buf[1] = wire[*pos + 1]; 89 pointer_target = ldns_read_uint16(pointer_target_buf); 90 91 if (pointer_target == 0) { 92 return LDNS_STATUS_INVALID_POINTER; 93 } else if (pointer_target >= max) { 94 return LDNS_STATUS_INVALID_POINTER; 95 } else if (pointer_count > LDNS_MAX_POINTERS) { 96 return LDNS_STATUS_INVALID_POINTER; 97 } 98 *pos = pointer_target; 99 label_size = wire[*pos]; 100 } 101 if(label_size == 0) 102 break; /* break from pointer to 0 byte */ 103 if (label_size > LDNS_MAX_LABELLEN) { 104 return LDNS_STATUS_LABEL_OVERFLOW; 105 } 106 if (*pos + 1 + label_size > max) { 107 return LDNS_STATUS_LABEL_OVERFLOW; 108 } 109 110 /* check space for labelcount itself */ 111 if (dname_pos + 1 > LDNS_MAX_DOMAINLEN) { 112 return LDNS_STATUS_DOMAINNAME_OVERFLOW; 113 } 114 tmp_dname[dname_pos] = label_size; 115 if (label_size > 0) { 116 dname_pos++; 117 } 118 *pos = *pos + 1; 119 if (dname_pos + label_size > LDNS_MAX_DOMAINLEN) { 120 return LDNS_STATUS_DOMAINNAME_OVERFLOW; 121 } 122 memcpy(&tmp_dname[dname_pos], &wire[*pos], label_size); 123 uncompressed_length += label_size + 1; 124 dname_pos += label_size; 125 *pos = *pos + label_size; 126 127 if (*pos < max) { 128 label_size = wire[*pos]; 129 } 130 } 131 132 if (compression_pos > 0) { 133 *pos = compression_pos; 134 } else { 135 *pos = *pos + 1; 136 } 137 138 if (dname_pos >= LDNS_MAX_DOMAINLEN) { 139 return LDNS_STATUS_DOMAINNAME_OVERFLOW; 140 } 141 142 tmp_dname[dname_pos] = 0; 143 dname_pos++; 144 145 *dname = ldns_rdf_new_frm_data(LDNS_RDF_TYPE_DNAME, 146 (uint16_t) dname_pos, tmp_dname); 147 if (!*dname) { 148 return LDNS_STATUS_MEM_ERR; 149 } 150 return LDNS_STATUS_OK; 151 } 152 153 /* maybe make this a goto error so data can be freed or something/ */ 154 #define LDNS_STATUS_CHECK_RETURN(st) {if (st != LDNS_STATUS_OK) { return st; }} 155 #define LDNS_STATUS_CHECK_GOTO(st, label) {if (st != LDNS_STATUS_OK) { /*printf("STG %s:%d: status code %d\n", __FILE__, __LINE__, st);*/ goto label; }} 156 157 ldns_status 158 ldns_wire2rdf(ldns_rr *rr, const uint8_t *wire, size_t max, size_t *pos) 159 { 160 size_t end; 161 size_t cur_rdf_length; 162 uint8_t rdf_index; 163 uint8_t *data; 164 uint16_t rd_length; 165 ldns_rdf *cur_rdf = NULL; 166 ldns_rdf_type cur_rdf_type; 167 const ldns_rr_descriptor *descriptor; 168 ldns_status status; 169 170 assert(rr != NULL); 171 172 descriptor = ldns_rr_descript(ldns_rr_get_type(rr)); 173 174 if (*pos + 2 > max) { 175 return LDNS_STATUS_PACKET_OVERFLOW; 176 } 177 178 rd_length = ldns_read_uint16(&wire[*pos]); 179 *pos = *pos + 2; 180 181 if (*pos + rd_length > max) { 182 return LDNS_STATUS_PACKET_OVERFLOW; 183 } 184 185 end = *pos + (size_t) rd_length; 186 187 rdf_index = 0; 188 while (*pos < end && 189 rdf_index < ldns_rr_descriptor_maximum(descriptor)) { 190 191 cur_rdf_length = 0; 192 193 cur_rdf_type = ldns_rr_descriptor_field_type( 194 descriptor, rdf_index); 195 196 /* handle special cases immediately, set length 197 for fixed length rdata and do them below */ 198 switch (cur_rdf_type) { 199 case LDNS_RDF_TYPE_DNAME: 200 status = ldns_wire2dname(&cur_rdf, wire, max, pos); 201 LDNS_STATUS_CHECK_RETURN(status); 202 break; 203 case LDNS_RDF_TYPE_CLASS: 204 case LDNS_RDF_TYPE_ALG: 205 case LDNS_RDF_TYPE_INT8: 206 cur_rdf_length = LDNS_RDF_SIZE_BYTE; 207 break; 208 case LDNS_RDF_TYPE_TYPE: 209 case LDNS_RDF_TYPE_INT16: 210 case LDNS_RDF_TYPE_CERT_ALG: 211 cur_rdf_length = LDNS_RDF_SIZE_WORD; 212 break; 213 case LDNS_RDF_TYPE_TIME: 214 case LDNS_RDF_TYPE_INT32: 215 case LDNS_RDF_TYPE_A: 216 case LDNS_RDF_TYPE_PERIOD: 217 cur_rdf_length = LDNS_RDF_SIZE_DOUBLEWORD; 218 break; 219 case LDNS_RDF_TYPE_TSIGTIME: 220 case LDNS_RDF_TYPE_EUI48: 221 cur_rdf_length = LDNS_RDF_SIZE_6BYTES; 222 break; 223 case LDNS_RDF_TYPE_ILNP64: 224 case LDNS_RDF_TYPE_EUI64: 225 cur_rdf_length = LDNS_RDF_SIZE_8BYTES; 226 break; 227 case LDNS_RDF_TYPE_AAAA: 228 cur_rdf_length = LDNS_RDF_SIZE_16BYTES; 229 break; 230 case LDNS_RDF_TYPE_STR: 231 case LDNS_RDF_TYPE_NSEC3_SALT: 232 case LDNS_RDF_TYPE_TAG: 233 /* len is stored in first byte 234 * it should be in the rdf too, so just 235 * copy len+1 from this position 236 */ 237 cur_rdf_length = ((size_t) wire[*pos]) + 1; 238 break; 239 240 case LDNS_RDF_TYPE_INT16_DATA: 241 if (*pos + 2 > end) { 242 return LDNS_STATUS_PACKET_OVERFLOW; 243 } 244 cur_rdf_length = 245 (size_t) ldns_read_uint16(&wire[*pos]) + 2; 246 break; 247 case LDNS_RDF_TYPE_HIP: 248 if (*pos + 4 > end) { 249 return LDNS_STATUS_PACKET_OVERFLOW; 250 } 251 cur_rdf_length = 252 (size_t) wire[*pos] + 253 (size_t) ldns_read_uint16(&wire[*pos + 2]) + 4; 254 break; 255 case LDNS_RDF_TYPE_B32_EXT: 256 case LDNS_RDF_TYPE_NSEC3_NEXT_OWNER: 257 /* length is stored in first byte */ 258 cur_rdf_length = ((size_t) wire[*pos]) + 1; 259 break; 260 case LDNS_RDF_TYPE_APL: 261 case LDNS_RDF_TYPE_B64: 262 case LDNS_RDF_TYPE_HEX: 263 case LDNS_RDF_TYPE_NSEC: 264 case LDNS_RDF_TYPE_UNKNOWN: 265 case LDNS_RDF_TYPE_SERVICE: 266 case LDNS_RDF_TYPE_LOC: 267 case LDNS_RDF_TYPE_WKS: 268 case LDNS_RDF_TYPE_NSAP: 269 case LDNS_RDF_TYPE_ATMA: 270 case LDNS_RDF_TYPE_IPSECKEY: 271 case LDNS_RDF_TYPE_LONG_STR: 272 case LDNS_RDF_TYPE_NONE: 273 /* 274 * Read to end of rr rdata 275 */ 276 cur_rdf_length = end - *pos; 277 break; 278 } 279 280 /* fixed length rdata */ 281 if (cur_rdf_length > 0) { 282 if (cur_rdf_length + *pos > end) { 283 return LDNS_STATUS_PACKET_OVERFLOW; 284 } 285 data = LDNS_XMALLOC(uint8_t, rd_length); 286 if (!data) { 287 return LDNS_STATUS_MEM_ERR; 288 } 289 memcpy(data, &wire[*pos], cur_rdf_length); 290 291 cur_rdf = ldns_rdf_new(cur_rdf_type, 292 cur_rdf_length, data); 293 *pos = *pos + cur_rdf_length; 294 } 295 296 if (cur_rdf) { 297 ldns_rr_push_rdf(rr, cur_rdf); 298 cur_rdf = NULL; 299 } 300 301 rdf_index++; 302 303 } /* while (rdf_index < ldns_rr_descriptor_maximum(descriptor)) */ 304 305 306 return LDNS_STATUS_OK; 307 } 308 309 310 /* TODO: 311 can *pos be incremented at READ_INT? or maybe use something like 312 RR_CLASS(wire)? 313 uhhm Jelte?? 314 */ 315 ldns_status 316 ldns_wire2rr(ldns_rr **rr_p, const uint8_t *wire, size_t max, 317 size_t *pos, ldns_pkt_section section) 318 { 319 ldns_rdf *owner = NULL; 320 ldns_rr *rr = ldns_rr_new(); 321 ldns_status status; 322 323 status = ldns_wire2dname(&owner, wire, max, pos); 324 LDNS_STATUS_CHECK_GOTO(status, status_error); 325 326 ldns_rr_set_owner(rr, owner); 327 328 if (*pos + 4 > max) { 329 status = LDNS_STATUS_PACKET_OVERFLOW; 330 goto status_error; 331 } 332 333 ldns_rr_set_type(rr, ldns_read_uint16(&wire[*pos])); 334 *pos = *pos + 2; 335 336 ldns_rr_set_class(rr, ldns_read_uint16(&wire[*pos])); 337 *pos = *pos + 2; 338 339 if (section != LDNS_SECTION_QUESTION) { 340 if (*pos + 4 > max) { 341 status = LDNS_STATUS_PACKET_OVERFLOW; 342 goto status_error; 343 } 344 ldns_rr_set_ttl(rr, ldns_read_uint32(&wire[*pos])); 345 346 *pos = *pos + 4; 347 status = ldns_wire2rdf(rr, wire, max, pos); 348 349 LDNS_STATUS_CHECK_GOTO(status, status_error); 350 ldns_rr_set_question(rr, false); 351 } else { 352 ldns_rr_set_question(rr, true); 353 } 354 355 *rr_p = rr; 356 return LDNS_STATUS_OK; 357 358 status_error: 359 ldns_rr_free(rr); 360 return status; 361 } 362 363 static ldns_status 364 ldns_wire2pkt_hdr(ldns_pkt *packet, const uint8_t *wire, size_t max, size_t *pos) 365 { 366 if (*pos + LDNS_HEADER_SIZE > max) { 367 return LDNS_STATUS_WIRE_INCOMPLETE_HEADER; 368 } else { 369 ldns_pkt_set_id(packet, LDNS_ID_WIRE(wire)); 370 ldns_pkt_set_qr(packet, LDNS_QR_WIRE(wire)); 371 ldns_pkt_set_opcode(packet, LDNS_OPCODE_WIRE(wire)); 372 ldns_pkt_set_aa(packet, LDNS_AA_WIRE(wire)); 373 ldns_pkt_set_tc(packet, LDNS_TC_WIRE(wire)); 374 ldns_pkt_set_rd(packet, LDNS_RD_WIRE(wire)); 375 ldns_pkt_set_ra(packet, LDNS_RA_WIRE(wire)); 376 ldns_pkt_set_ad(packet, LDNS_AD_WIRE(wire)); 377 ldns_pkt_set_cd(packet, LDNS_CD_WIRE(wire)); 378 ldns_pkt_set_rcode(packet, LDNS_RCODE_WIRE(wire)); 379 380 ldns_pkt_set_qdcount(packet, LDNS_QDCOUNT(wire)); 381 ldns_pkt_set_ancount(packet, LDNS_ANCOUNT(wire)); 382 ldns_pkt_set_nscount(packet, LDNS_NSCOUNT(wire)); 383 ldns_pkt_set_arcount(packet, LDNS_ARCOUNT(wire)); 384 385 *pos += LDNS_HEADER_SIZE; 386 387 return LDNS_STATUS_OK; 388 } 389 } 390 391 ldns_status 392 ldns_buffer2pkt_wire(ldns_pkt **packet, ldns_buffer *buffer) 393 { 394 /* lazy */ 395 return ldns_wire2pkt(packet, ldns_buffer_begin(buffer), 396 ldns_buffer_limit(buffer)); 397 398 } 399 400 ldns_status 401 ldns_wire2pkt(ldns_pkt **packet_p, const uint8_t *wire, size_t max) 402 { 403 size_t pos = 0; 404 uint16_t i; 405 ldns_rr *rr; 406 ldns_pkt *packet = ldns_pkt_new(); 407 ldns_status status = LDNS_STATUS_OK; 408 int have_edns = 0; 409 410 uint8_t data[4]; 411 412 status = ldns_wire2pkt_hdr(packet, wire, max, &pos); 413 LDNS_STATUS_CHECK_GOTO(status, status_error); 414 415 for (i = 0; i < ldns_pkt_qdcount(packet); i++) { 416 417 status = ldns_wire2rr(&rr, wire, max, &pos, LDNS_SECTION_QUESTION); 418 if (status == LDNS_STATUS_PACKET_OVERFLOW) { 419 status = LDNS_STATUS_WIRE_INCOMPLETE_QUESTION; 420 } 421 LDNS_STATUS_CHECK_GOTO(status, status_error); 422 if (!ldns_rr_list_push_rr(ldns_pkt_question(packet), rr)) { 423 ldns_pkt_free(packet); 424 return LDNS_STATUS_INTERNAL_ERR; 425 } 426 } 427 for (i = 0; i < ldns_pkt_ancount(packet); i++) { 428 status = ldns_wire2rr(&rr, wire, max, &pos, LDNS_SECTION_ANSWER); 429 if (status == LDNS_STATUS_PACKET_OVERFLOW) { 430 status = LDNS_STATUS_WIRE_INCOMPLETE_ANSWER; 431 } 432 LDNS_STATUS_CHECK_GOTO(status, status_error); 433 if (!ldns_rr_list_push_rr(ldns_pkt_answer(packet), rr)) { 434 ldns_pkt_free(packet); 435 return LDNS_STATUS_INTERNAL_ERR; 436 } 437 } 438 for (i = 0; i < ldns_pkt_nscount(packet); i++) { 439 status = ldns_wire2rr(&rr, wire, max, &pos, LDNS_SECTION_AUTHORITY); 440 if (status == LDNS_STATUS_PACKET_OVERFLOW) { 441 status = LDNS_STATUS_WIRE_INCOMPLETE_AUTHORITY; 442 } 443 LDNS_STATUS_CHECK_GOTO(status, status_error); 444 if (!ldns_rr_list_push_rr(ldns_pkt_authority(packet), rr)) { 445 ldns_pkt_free(packet); 446 return LDNS_STATUS_INTERNAL_ERR; 447 } 448 } 449 for (i = 0; i < ldns_pkt_arcount(packet); i++) { 450 status = ldns_wire2rr(&rr, wire, max, &pos, LDNS_SECTION_ADDITIONAL); 451 if (status == LDNS_STATUS_PACKET_OVERFLOW) { 452 status = LDNS_STATUS_WIRE_INCOMPLETE_ADDITIONAL; 453 } 454 LDNS_STATUS_CHECK_GOTO(status, status_error); 455 456 if (ldns_rr_get_type(rr) == LDNS_RR_TYPE_OPT) { 457 ldns_pkt_set_edns_udp_size(packet, ldns_rr_get_class(rr)); 458 ldns_write_uint32(data, ldns_rr_ttl(rr)); 459 ldns_pkt_set_edns_extended_rcode(packet, data[0]); 460 ldns_pkt_set_edns_version(packet, data[1]); 461 ldns_pkt_set_edns_z(packet, ldns_read_uint16(&data[2])); 462 /* edns might not have rdfs */ 463 if (ldns_rr_rdf(rr, 0)) { 464 ldns_pkt_set_edns_data(packet, ldns_rdf_clone(ldns_rr_rdf(rr, 0))); 465 } 466 ldns_rr_free(rr); 467 have_edns += 1; 468 } else if (ldns_rr_get_type(rr) == LDNS_RR_TYPE_TSIG) { 469 ldns_pkt_set_tsig(packet, rr); 470 ldns_pkt_set_arcount(packet, ldns_pkt_arcount(packet) - 1); 471 } else if (!ldns_rr_list_push_rr(ldns_pkt_additional(packet), rr)) { 472 ldns_pkt_free(packet); 473 return LDNS_STATUS_INTERNAL_ERR; 474 } 475 } 476 ldns_pkt_set_size(packet, max); 477 if(have_edns) 478 ldns_pkt_set_arcount(packet, ldns_pkt_arcount(packet) 479 - have_edns); 480 481 *packet_p = packet; 482 return status; 483 484 status_error: 485 ldns_pkt_free(packet); 486 return status; 487 } 488