contrib/ldns/wire2host.c

   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 >= max) {
  68                 return LDNS_STATUS_PACKET_OVERFLOW;
  69         }
  70
  71         label_size = wire[*pos];
  72         while (label_size > 0) {
  73                 /* compression */
  74                 while (label_size >= 192) {
  75                         if (compression_pos == 0) {
  76                                 compression_pos = *pos + 2;
  77                         }
  78
  79                         pointer_count++;
  80
  81                         /* remove first two bits */
  82                         if (*pos + 2 > max) {
  83                                 return LDNS_STATUS_PACKET_OVERFLOW;
  84                         }
  85                         pointer_target_buf[0] = wire[*pos] & 63;
  86                         pointer_target_buf[1] = wire[*pos + 1];
  87                         pointer_target = ldns_read_uint16(pointer_target_buf);
  88
  89                         if (pointer_target == 0) {
  90                                 return LDNS_STATUS_INVALID_POINTER;
  91                         } else if (pointer_target >= max) {
  92                                 return LDNS_STATUS_INVALID_POINTER;
  93                         } else if (pointer_count > LDNS_MAX_POINTERS) {
  94                                 return LDNS_STATUS_INVALID_POINTER;
  95                         }
  96                         *pos = pointer_target;
  97                         label_size = wire[*pos];
  98                 }
  99                 if(label_size == 0)
 100                         break; /* break from pointer to 0 byte */
 101                 if (label_size > LDNS_MAX_LABELLEN) {
 102                         return LDNS_STATUS_LABEL_OVERFLOW;
 103                 }
 104                 if (*pos + 1 + label_size > max) {
 105                         return LDNS_STATUS_LABEL_OVERFLOW;
 106                 }
 107
 108                 /* check space for labelcount itself */
 109                 if (dname_pos + 1 > LDNS_MAX_DOMAINLEN) {
 110                         return LDNS_STATUS_DOMAINNAME_OVERFLOW;
 111                 }
 112                 tmp_dname[dname_pos] = label_size;
 113                 if (label_size > 0) {
 114                         dname_pos++;
 115                 }
 116                 *pos = *pos + 1;
 117                 if (dname_pos + label_size > LDNS_MAX_DOMAINLEN) {
 118                         return LDNS_STATUS_DOMAINNAME_OVERFLOW;
 119                 }
 120                 memcpy(&tmp_dname[dname_pos], &wire[*pos], label_size);
 121                 uncompressed_length += label_size + 1;
 122                 dname_pos += label_size;
 123                 *pos = *pos + label_size;
 124
 125                 if (*pos < max) {
 126                         label_size = wire[*pos];
 127                 }
 128         }
 129
 130         if (compression_pos > 0) {
 131                 *pos = compression_pos;
 132         } else {
 133                 *pos = *pos + 1;
 134         }
 135
 136         if (dname_pos >= LDNS_MAX_DOMAINLEN) {
 137                 return LDNS_STATUS_DOMAINNAME_OVERFLOW;
 138         }
 139
 140         tmp_dname[dname_pos] = 0;
 141         dname_pos++;
 142
 143         *dname = ldns_rdf_new_frm_data(LDNS_RDF_TYPE_DNAME,
 144                         (uint16_t) dname_pos, tmp_dname);
 145         if (!*dname) {
 146                 return LDNS_STATUS_MEM_ERR;
 147         }
 148         return LDNS_STATUS_OK;
 149 }
 150
 151 /* maybe make this a goto error so data can be freed or something/ */
 152 #define LDNS_STATUS_CHECK_RETURN(st) {if (st != LDNS_STATUS_OK) { return st; }}
 153 #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; }}
 154
 155 ldns_status
 156 ldns_wire2rdf(ldns_rr *rr, const uint8_t *wire, size_t max, size_t *pos)
 157 {
 158         size_t end;
 159         size_t cur_rdf_length;
 160         uint8_t rdf_index;
 161         uint8_t *data;
 162         uint16_t rd_length;
 163         ldns_rdf *cur_rdf = NULL;
 164         ldns_rdf_type cur_rdf_type;
 165         const ldns_rr_descriptor *descriptor = ldns_rr_descript(ldns_rr_get_type(rr));
 166         ldns_status status;
 167
 168         if (*pos + 2 > max) {
 169                 return LDNS_STATUS_PACKET_OVERFLOW;
 170         }
 171
 172         rd_length = ldns_read_uint16(&wire[*pos]);
 173         *pos = *pos + 2;
 174
 175         if (*pos + rd_length > max) {
 176                 return LDNS_STATUS_PACKET_OVERFLOW;
 177         }
 178
 179         end = *pos + (size_t) rd_length;
 180
 181         for (rdf_index = 0;
 182              rdf_index < ldns_rr_descriptor_maximum(descriptor); rdf_index++) {
 183                 if (*pos >= end) {
 184                         break;
 185                 }
 186                 cur_rdf_length = 0;
 187
 188                 cur_rdf_type = ldns_rr_descriptor_field_type(descriptor, rdf_index);
 189                 /* handle special cases immediately, set length
 190                    for fixed length rdata and do them below */
 191                 switch (cur_rdf_type) {
 192                 case LDNS_RDF_TYPE_DNAME:
 193                         status = ldns_wire2dname(&cur_rdf, wire, max, pos);
 194                         LDNS_STATUS_CHECK_RETURN(status);
 195                         break;
 196                 case LDNS_RDF_TYPE_CLASS:
 197                 case LDNS_RDF_TYPE_ALG:
 198                 case LDNS_RDF_TYPE_INT8:
 199                         cur_rdf_length = LDNS_RDF_SIZE_BYTE;
 200                         break;
 201                 case LDNS_RDF_TYPE_TYPE:
 202                 case LDNS_RDF_TYPE_INT16:
 203                 case LDNS_RDF_TYPE_CERT_ALG:
 204                         cur_rdf_length = LDNS_RDF_SIZE_WORD;
 205                         break;
 206                 case LDNS_RDF_TYPE_TIME:
 207                 case LDNS_RDF_TYPE_INT32:
 208                 case LDNS_RDF_TYPE_A:
 209                 case LDNS_RDF_TYPE_PERIOD:
 210                         cur_rdf_length = LDNS_RDF_SIZE_DOUBLEWORD;
 211                         break;
 212                 case LDNS_RDF_TYPE_TSIGTIME:
 213                         cur_rdf_length = LDNS_RDF_SIZE_6BYTES;
 214                         break;
 215                 case LDNS_RDF_TYPE_AAAA:
 216                         cur_rdf_length = LDNS_RDF_SIZE_16BYTES;
 217                         break;
 218                 case LDNS_RDF_TYPE_STR:
 219                 case LDNS_RDF_TYPE_NSEC3_SALT:
 220                         /* len is stored in first byte
 221                          * it should be in the rdf too, so just
 222                          * copy len+1 from this position
 223                          */
 224                         cur_rdf_length = ((size_t) wire[*pos]) + 1;
 225                         break;
 226                 case LDNS_RDF_TYPE_INT16_DATA:
 227                         cur_rdf_length = (size_t) ldns_read_uint16(&wire[*pos]) + 2;
 228                         break;
 229                 case LDNS_RDF_TYPE_B32_EXT:
 230                 case LDNS_RDF_TYPE_NSEC3_NEXT_OWNER:
 231                         /* length is stored in first byte */
 232                         cur_rdf_length = ((size_t) wire[*pos]) + 1;
 233                         break;
 234                 case LDNS_RDF_TYPE_APL:
 235                 case LDNS_RDF_TYPE_B64:
 236                 case LDNS_RDF_TYPE_HEX:
 237                 case LDNS_RDF_TYPE_NSEC:
 238                 case LDNS_RDF_TYPE_UNKNOWN:
 239                 case LDNS_RDF_TYPE_SERVICE:
 240                 case LDNS_RDF_TYPE_LOC:
 241                 case LDNS_RDF_TYPE_WKS:
 242                 case LDNS_RDF_TYPE_NSAP:
 243                 case LDNS_RDF_TYPE_ATMA:
 244                 case LDNS_RDF_TYPE_IPSECKEY:
 245                 case LDNS_RDF_TYPE_TSIG:
 246                 case LDNS_RDF_TYPE_NONE:
 247                         /*
 248                          * Read to end of rr rdata
 249                          */
 250                         cur_rdf_length = end - *pos;
 251                         break;
 252                 }
 253
 254                 /* fixed length rdata */
 255                 if (cur_rdf_length > 0) {
 256                         if (cur_rdf_length + *pos > end) {
 257                                 return LDNS_STATUS_PACKET_OVERFLOW;
 258                         }
 259                         data = LDNS_XMALLOC(uint8_t, rd_length);
 260                         if (!data) {
 261                                 return LDNS_STATUS_MEM_ERR;
 262                         }
 263                         memcpy(data, &wire[*pos], cur_rdf_length);
 264
 265                         cur_rdf = ldns_rdf_new(cur_rdf_type, cur_rdf_length, data);
 266                         *pos = *pos + cur_rdf_length;
 267                 }
 268
 269                 if (cur_rdf) {
 270                         ldns_rr_push_rdf(rr, cur_rdf);
 271                         cur_rdf = NULL;
 272                 }
 273         }
 274
 275         return LDNS_STATUS_OK;
 276 }
 277
 278
 279 /* TODO:
 280          can *pos be incremented at READ_INT? or maybe use something like
 281          RR_CLASS(wire)?
 282          uhhm Jelte??
 283 */
 284 ldns_status
 285 ldns_wire2rr(ldns_rr **rr_p, const uint8_t *wire, size_t max,
 286              size_t *pos, ldns_pkt_section section)
 287 {
 288         ldns_rdf *owner = NULL;
 289         ldns_rr *rr = ldns_rr_new();
 290         ldns_status status;
 291
 292         status = ldns_wire2dname(&owner, wire, max, pos);
 293         LDNS_STATUS_CHECK_GOTO(status, status_error);
 294
 295         ldns_rr_set_owner(rr, owner);
 296
 297         if (*pos + 4 > max) {
 298                 status = LDNS_STATUS_PACKET_OVERFLOW;
 299                 goto status_error;
 300         }
 301
 302         ldns_rr_set_type(rr, ldns_read_uint16(&wire[*pos]));
 303         *pos = *pos + 2;
 304
 305         ldns_rr_set_class(rr, ldns_read_uint16(&wire[*pos]));
 306         *pos = *pos + 2;
 307
 308         if (section != LDNS_SECTION_QUESTION) {
 309                 if (*pos + 4 > max) {
 310                         status = LDNS_STATUS_PACKET_OVERFLOW;
 311                         goto status_error;
 312                 }
 313                 ldns_rr_set_ttl(rr, ldns_read_uint32(&wire[*pos]));
 314
 315                 *pos = *pos + 4;
 316                 status = ldns_wire2rdf(rr, wire, max, pos);
 317
 318                 LDNS_STATUS_CHECK_GOTO(status, status_error);
 319         ldns_rr_set_question(rr, false);
 320         } else {
 321         ldns_rr_set_question(rr, true);
 322     }
 323
 324         *rr_p = rr;
 325         return LDNS_STATUS_OK;
 326
 327 status_error:
 328         ldns_rr_free(rr);
 329         return status;
 330 }
 331
 332 static ldns_status
 333 ldns_wire2pkt_hdr(ldns_pkt *packet, const uint8_t *wire, size_t max, size_t *pos)
 334 {
 335         if (*pos + LDNS_HEADER_SIZE > max) {
 336                 return LDNS_STATUS_WIRE_INCOMPLETE_HEADER;
 337         } else {
 338                 ldns_pkt_set_id(packet, LDNS_ID_WIRE(wire));
 339                 ldns_pkt_set_qr(packet, LDNS_QR_WIRE(wire));
 340                 ldns_pkt_set_opcode(packet, LDNS_OPCODE_WIRE(wire));
 341                 ldns_pkt_set_aa(packet, LDNS_AA_WIRE(wire));
 342                 ldns_pkt_set_tc(packet, LDNS_TC_WIRE(wire));
 343                 ldns_pkt_set_rd(packet, LDNS_RD_WIRE(wire));
 344                 ldns_pkt_set_ra(packet, LDNS_RA_WIRE(wire));
 345                 ldns_pkt_set_ad(packet, LDNS_AD_WIRE(wire));
 346                 ldns_pkt_set_cd(packet, LDNS_CD_WIRE(wire));
 347                 ldns_pkt_set_rcode(packet, LDNS_RCODE_WIRE(wire));
 348
 349                 ldns_pkt_set_qdcount(packet, LDNS_QDCOUNT(wire));
 350                 ldns_pkt_set_ancount(packet, LDNS_ANCOUNT(wire));
 351                 ldns_pkt_set_nscount(packet, LDNS_NSCOUNT(wire));
 352                 ldns_pkt_set_arcount(packet, LDNS_ARCOUNT(wire));
 353
 354                 *pos += LDNS_HEADER_SIZE;
 355
 356                 return LDNS_STATUS_OK;
 357         }
 358 }
 359
 360 ldns_status
 361 ldns_buffer2pkt_wire(ldns_pkt **packet, ldns_buffer *buffer)
 362 {
 363         /* lazy */
 364         return ldns_wire2pkt(packet, ldns_buffer_begin(buffer),
 365                                 ldns_buffer_limit(buffer));
 366
 367 }
 368
 369 ldns_status
 370 ldns_wire2pkt(ldns_pkt **packet_p, const uint8_t *wire, size_t max)
 371 {
 372         size_t pos = 0;
 373         uint16_t i;
 374         ldns_rr *rr;
 375         ldns_pkt *packet = ldns_pkt_new();
 376         ldns_status status = LDNS_STATUS_OK;
 377         int have_edns = 0;
 378
 379         uint8_t data[4];
 380
 381         status = ldns_wire2pkt_hdr(packet, wire, max, &pos);
 382         LDNS_STATUS_CHECK_GOTO(status, status_error);
 383
 384         for (i = 0; i < ldns_pkt_qdcount(packet); i++) {
 385
 386                 status = ldns_wire2rr(&rr, wire, max, &pos, LDNS_SECTION_QUESTION);
 387                 if (status == LDNS_STATUS_PACKET_OVERFLOW) {
 388                         status = LDNS_STATUS_WIRE_INCOMPLETE_QUESTION;
 389                 }
 390                 LDNS_STATUS_CHECK_GOTO(status, status_error);
 391                 if (!ldns_rr_list_push_rr(ldns_pkt_question(packet), rr)) {
 392                         ldns_pkt_free(packet);
 393                         return LDNS_STATUS_INTERNAL_ERR;
 394                 }
 395         }
 396         for (i = 0; i < ldns_pkt_ancount(packet); i++) {
 397                 status = ldns_wire2rr(&rr, wire, max, &pos, LDNS_SECTION_ANSWER);
 398                 if (status == LDNS_STATUS_PACKET_OVERFLOW) {
 399                         status = LDNS_STATUS_WIRE_INCOMPLETE_ANSWER;
 400                 }
 401                 LDNS_STATUS_CHECK_GOTO(status, status_error);
 402                 if (!ldns_rr_list_push_rr(ldns_pkt_answer(packet), rr)) {
 403                         ldns_pkt_free(packet);
 404                         return LDNS_STATUS_INTERNAL_ERR;
 405                 }
 406         }
 407         for (i = 0; i < ldns_pkt_nscount(packet); i++) {
 408                 status = ldns_wire2rr(&rr, wire, max, &pos, LDNS_SECTION_AUTHORITY);
 409                 if (status == LDNS_STATUS_PACKET_OVERFLOW) {
 410                         status = LDNS_STATUS_WIRE_INCOMPLETE_AUTHORITY;
 411                 }
 412                 LDNS_STATUS_CHECK_GOTO(status, status_error);
 413                 if (!ldns_rr_list_push_rr(ldns_pkt_authority(packet), rr)) {
 414                         ldns_pkt_free(packet);
 415                         return LDNS_STATUS_INTERNAL_ERR;
 416                 }
 417         }
 418         for (i = 0; i < ldns_pkt_arcount(packet); i++) {
 419                 status = ldns_wire2rr(&rr, wire, max, &pos, LDNS_SECTION_ADDITIONAL);
 420                 if (status == LDNS_STATUS_PACKET_OVERFLOW) {
 421                         status = LDNS_STATUS_WIRE_INCOMPLETE_ADDITIONAL;
 422                 }
 423                 LDNS_STATUS_CHECK_GOTO(status, status_error);
 424
 425                 if (ldns_rr_get_type(rr) == LDNS_RR_TYPE_OPT) {
 426                         ldns_pkt_set_edns_udp_size(packet, ldns_rr_get_class(rr));
 427                         ldns_write_uint32(data, ldns_rr_ttl(rr));
 428                         ldns_pkt_set_edns_extended_rcode(packet, data[0]);
 429                         ldns_pkt_set_edns_version(packet, data[1]);
 430                         ldns_pkt_set_edns_z(packet, ldns_read_uint16(&data[2]));
 431                         /* edns might not have rdfs */
 432                         if (ldns_rr_rdf(rr, 0)) {
 433                                 ldns_pkt_set_edns_data(packet, ldns_rdf_clone(ldns_rr_rdf(rr, 0)));
 434                         }
 435                         ldns_rr_free(rr);
 436                         have_edns += 1;
 437                 } else if (ldns_rr_get_type(rr) == LDNS_RR_TYPE_TSIG) {
 438                         ldns_pkt_set_tsig(packet, rr);
 439                         ldns_pkt_set_arcount(packet, ldns_pkt_arcount(packet) - 1);
 440                 } else if (!ldns_rr_list_push_rr(ldns_pkt_additional(packet), rr)) {
 441                         ldns_pkt_free(packet);
 442                         return LDNS_STATUS_INTERNAL_ERR;
 443                 }
 444         }
 445         ldns_pkt_set_size(packet, max);
 446         if(have_edns)
 447                 ldns_pkt_set_arcount(packet, ldns_pkt_arcount(packet)
 448                         - have_edns);
 449
 450         *packet_p = packet;
 451         return status;
 452
 453 status_error:
 454         ldns_pkt_free(packet);
 455         return status;
 456 }