git.meshlink.io Git - catta/blob - avahi-core/dns.c

   1 /* $Id$ */
   2
   3 /***
   4   This file is part of avahi.
   5
   6   avahi is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as
   8   published by the Free Software Foundation; either version 2.1 of the
   9   License, or (at your option) any later version.
  10
  11   avahi is distributed in the hope that it will be useful, but WITHOUT
  12   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  13   or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
  14   Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public
  17   License along with avahi; if not, write to the Free Software
  18   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  19   USA.
  20 ***/
  21
  22 #ifdef HAVE_CONFIG_H
  23 #include <config.h>
  24 #endif
  25
  26 #include <stdlib.h>
  27 #include <string.h>
  28 #include <stdio.h>
  29 #include <assert.h>
  30
  31 #include <sys/types.h>
  32 #include <netinet/in.h>
  33
  34 #include <avahi-common/defs.h>
  35 #include <avahi-common/domain.h>
  36 #include <avahi-common/malloc.h>
  37
  38 #include "dns.h"
  39 #include "log.h"
  40
  41 AvahiDnsPacket* avahi_dns_packet_new(unsigned mtu) {
  42     AvahiDnsPacket *p;
  43     size_t max_size;
  44
  45     if (mtu <= 0)
  46         max_size = AVAHI_DNS_PACKET_SIZE_MAX;
  47     else if (mtu >= AVAHI_DNS_PACKET_EXTRA_SIZE)
  48         max_size = mtu - AVAHI_DNS_PACKET_EXTRA_SIZE;
  49     else
  50         max_size = 0;
  51
  52     if (max_size < AVAHI_DNS_PACKET_HEADER_SIZE)
  53         max_size = AVAHI_DNS_PACKET_HEADER_SIZE;
  54
  55     if (!(p = avahi_malloc(sizeof(AvahiDnsPacket) + max_size)))
  56         return p;
  57
  58     p->size = p->rindex = AVAHI_DNS_PACKET_HEADER_SIZE;
  59     p->max_size = max_size;
  60     p->name_table = NULL;
  61     p->data = NULL;
  62
  63     memset(AVAHI_DNS_PACKET_DATA(p), 0, p->size);
  64     return p;
  65 }
  66
  67 AvahiDnsPacket* avahi_dns_packet_new_query(unsigned mtu) {
  68     AvahiDnsPacket *p;
  69
  70     if (!(p = avahi_dns_packet_new(mtu)))
  71         return NULL;
  72
  73     avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_FLAGS, AVAHI_DNS_FLAGS(0, 0, 0, 0, 0, 0, 0, 0, 0, 0));
  74     return p;
  75 }
  76
  77 AvahiDnsPacket* avahi_dns_packet_new_response(unsigned mtu, int aa) {
  78     AvahiDnsPacket *p;
  79
  80     if (!(p = avahi_dns_packet_new(mtu)))
  81         return NULL;
  82
  83     avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_FLAGS, AVAHI_DNS_FLAGS(1, 0, aa, 0, 0, 0, 0, 0, 0, 0));
  84     return p;
  85 }
  86
  87 AvahiDnsPacket* avahi_dns_packet_new_reply(AvahiDnsPacket* p, unsigned mtu, int copy_queries, int aa) {
  88     AvahiDnsPacket *r;
  89     assert(p);
  90
  91     if (!(r = avahi_dns_packet_new_response(mtu, aa)))
  92         return NULL;
  93
  94     if (copy_queries) {
  95         unsigned saved_rindex;
  96         uint32_t n;
  97
  98         saved_rindex = p->rindex;
  99         p->rindex = AVAHI_DNS_PACKET_HEADER_SIZE;
 100
 101         for (n = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_QDCOUNT); n > 0; n--) {
 102             AvahiKey *k;
 103             int unicast_response;
 104
 105             if ((k = avahi_dns_packet_consume_key(p, &unicast_response))) {
 106                 avahi_dns_packet_append_key(r, k, unicast_response);
 107                 avahi_key_unref(k);
 108             }
 109         }
 110
 111         p->rindex = saved_rindex;
 112
 113         avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_QDCOUNT, avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_QDCOUNT));
 114     }
 115
 116     avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_ID, avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_ID));
 117
 118     avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_FLAGS,
 119                                (avahi_dns_packet_get_field(r, AVAHI_DNS_FIELD_FLAGS) & ~AVAHI_DNS_FLAG_OPCODE) |
 120                                (avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) & AVAHI_DNS_FLAG_OPCODE));
 121
 122     return r;
 123 }
 124
 125
 126 void avahi_dns_packet_free(AvahiDnsPacket *p) {
 127     assert(p);
 128
 129     if (p->name_table)
 130         avahi_hashmap_free(p->name_table);
 131
 132     avahi_free(p);
 133 }
 134
 135 void avahi_dns_packet_set_field(AvahiDnsPacket *p, unsigned idx, uint16_t v) {
 136     assert(p);
 137     assert(idx < AVAHI_DNS_PACKET_HEADER_SIZE);
 138
 139     ((uint16_t*) AVAHI_DNS_PACKET_DATA(p))[idx] = htons(v);
 140 }
 141
 142 uint16_t avahi_dns_packet_get_field(AvahiDnsPacket *p, unsigned idx) {
 143     assert(p);
 144     assert(idx < AVAHI_DNS_PACKET_HEADER_SIZE);
 145
 146     return ntohs(((uint16_t*) AVAHI_DNS_PACKET_DATA(p))[idx]);
 147 }
 148
 149 void avahi_dns_packet_inc_field(AvahiDnsPacket *p, unsigned idx) {
 150     assert(p);
 151     assert(idx < AVAHI_DNS_PACKET_HEADER_SIZE);
 152
 153     avahi_dns_packet_set_field(p, idx, avahi_dns_packet_get_field(p, idx) + 1);
 154 }
 155
 156
 157 static void
 158 name_table_cleanup(void *key, void *value, void *user_data) {
 159   AvahiDnsPacket *p = (AvahiDnsPacket *)user_data;
 160
 161   if ((uint8_t *)value >= AVAHI_DNS_PACKET_DATA(p) + p->size) {
 162     avahi_hashmap_remove(p->name_table, key);
 163   }
 164 }
 165
 166 void
 167 avahi_dns_packet_cleanup_name_table(AvahiDnsPacket *p) {
 168   if (p->name_table)
 169     avahi_hashmap_foreach(p->name_table, name_table_cleanup, p);
 170 }
 171
 172 uint8_t* avahi_dns_packet_append_name(AvahiDnsPacket *p, const char *name) {
 173     uint8_t *d, *saved_ptr = NULL;
 174     size_t saved_size;
 175
 176     assert(p);
 177     assert(name);
 178
 179     saved_size = p->size;
 180     saved_ptr = avahi_dns_packet_extend(p, 0);
 181
 182     while (*name) {
 183         uint8_t* prev;
 184         const char *pname;
 185         char label[64], *u;
 186
 187         /* Check whether we can compress this name. */
 188
 189         if (p->name_table && (prev = avahi_hashmap_lookup(p->name_table, name))) {
 190             unsigned idx;
 191
 192             assert(prev >= AVAHI_DNS_PACKET_DATA(p));
 193             idx = (unsigned) (prev - AVAHI_DNS_PACKET_DATA(p));
 194
 195             assert(idx < p->size);
 196
 197             if (idx < 0x4000) {
 198                 uint8_t *t;
 199                 if (!(t = (uint8_t*) avahi_dns_packet_extend(p, sizeof(uint16_t))))
 200                     return NULL;
 201
 202                 t[0] = (uint8_t) ((0xC000 | idx) >> 8);
 203                 t[1] = (uint8_t) idx;
 204                 return saved_ptr;
 205             }
 206         }
 207
 208         pname = name;
 209
 210         if (!(avahi_unescape_label(&name, label, sizeof(label))))
 211             goto fail;
 212
 213         if (!(d = avahi_dns_packet_append_string(p, label)))
 214             goto fail;
 215
 216         if (!p->name_table)
 217             /* This works only for normalized domain names */
 218             p->name_table = avahi_hashmap_new(avahi_string_hash, avahi_string_equal, avahi_free, NULL);
 219
 220         if (!(u = avahi_strdup(pname)))
 221             avahi_log_error("avahi_strdup() failed.");
 222         else
 223             avahi_hashmap_insert(p->name_table, u, d);
 224     }
 225
 226     if (!(d = avahi_dns_packet_extend(p, 1)))
 227         goto fail;
 228
 229     *d = 0;
 230
 231     return saved_ptr;
 232
 233 fail:
 234     p->size = saved_size;
 235     avahi_dns_packet_cleanup_name_table(p);
 236
 237     return NULL;
 238 }
 239
 240 uint8_t* avahi_dns_packet_append_uint16(AvahiDnsPacket *p, uint16_t v) {
 241     uint8_t *d;
 242     assert(p);
 243
 244     if (!(d = avahi_dns_packet_extend(p, sizeof(uint16_t))))
 245         return NULL;
 246
 247     d[0] = (uint8_t) (v >> 8);
 248     d[1] = (uint8_t) v;
 249     return d;
 250 }
 251
 252 uint8_t *avahi_dns_packet_append_uint32(AvahiDnsPacket *p, uint32_t v) {
 253     uint8_t *d;
 254     assert(p);
 255
 256     if (!(d = avahi_dns_packet_extend(p, sizeof(uint32_t))))
 257         return NULL;
 258
 259     d[0] = (uint8_t) (v >> 24);
 260     d[1] = (uint8_t) (v >> 16);
 261     d[2] = (uint8_t) (v >> 8);
 262     d[3] = (uint8_t) v;
 263
 264     return d;
 265 }
 266
 267 uint8_t *avahi_dns_packet_append_bytes(AvahiDnsPacket  *p, const void *b, size_t l) {
 268     uint8_t* d;
 269
 270     assert(p);
 271     assert(b);
 272     assert(l);
 273
 274     if (!(d = avahi_dns_packet_extend(p, l)))
 275         return NULL;
 276
 277     memcpy(d, b, l);
 278     return d;
 279 }
 280
 281 uint8_t* avahi_dns_packet_append_string(AvahiDnsPacket *p, const char *s) {
 282     uint8_t* d;
 283     size_t k;
 284
 285     assert(p);
 286     assert(s);
 287
 288     if ((k = strlen(s)) >= 255)
 289         k = 255;
 290
 291     if (!(d = avahi_dns_packet_extend(p, k+1)))
 292         return NULL;
 293
 294     *d = (uint8_t) k;
 295     memcpy(d+1, s, k);
 296
 297     return d;
 298 }
 299
 300 uint8_t *avahi_dns_packet_extend(AvahiDnsPacket *p, size_t l) {
 301     uint8_t *d;
 302
 303     assert(p);
 304
 305     if (p->size+l > p->max_size)
 306         return NULL;
 307
 308     d = AVAHI_DNS_PACKET_DATA(p) + p->size;
 309     p->size += l;
 310
 311     return d;
 312 }
 313
 314 int avahi_dns_packet_check_valid(AvahiDnsPacket *p) {
 315     uint16_t flags;
 316     assert(p);
 317
 318     if (p->size < AVAHI_DNS_PACKET_HEADER_SIZE)
 319         return -1;
 320
 321     flags = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS);
 322
 323     if (flags & AVAHI_DNS_FLAG_OPCODE)
 324         return -1;
 325
 326     return 0;
 327 }
 328
 329 int avahi_dns_packet_check_valid_multicast(AvahiDnsPacket *p) {
 330     uint16_t flags;
 331     assert(p);
 332
 333     if (avahi_dns_packet_check_valid(p) < 0)
 334         return -1;
 335
 336     flags = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS);
 337
 338     if (flags & AVAHI_DNS_FLAG_RCODE)
 339         return -1;
 340
 341     return 0;
 342 }
 343
 344 int avahi_dns_packet_is_query(AvahiDnsPacket *p) {
 345     assert(p);
 346
 347     return !(avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) & AVAHI_DNS_FLAG_QR);
 348 }
 349
 350 static int consume_labels(AvahiDnsPacket *p, unsigned idx, char *ret_name, size_t l) {
 351     int ret = 0;
 352     int compressed = 0;
 353     int first_label = 1;
 354     unsigned label_ptr;
 355     int i;
 356     assert(p && ret_name && l);
 357
 358     for (i = 0; i < AVAHI_DNS_LABELS_MAX; i++) {
 359         uint8_t n;
 360
 361         if (idx+1 > p->size)
 362             return -1;
 363
 364         n = AVAHI_DNS_PACKET_DATA(p)[idx];
 365
 366         if (!n) {
 367             idx++;
 368             if (!compressed)
 369                 ret++;
 370
 371             if (l < 1)
 372                 return -1;
 373             *ret_name = 0;
 374
 375             return ret;
 376
 377         } else if (n <= 63) {
 378             /* Uncompressed label */
 379             idx++;
 380             if (!compressed)
 381                 ret++;
 382
 383             if (idx + n > p->size)
 384                 return -1;
 385
 386             if ((size_t) n + 1 > l)
 387                 return -1;
 388
 389             if (!first_label) {
 390                 *(ret_name++) = '.';
 391                 l--;
 392             } else
 393                 first_label = 0;
 394
 395             if (!(avahi_escape_label((char*) AVAHI_DNS_PACKET_DATA(p) + idx, n, &ret_name, &l)))
 396                 return -1;
 397
 398             idx += n;
 399
 400             if (!compressed)
 401                 ret += n;
 402         } else if ((n & 0xC0) == 0xC0) {
 403             /* Compressed label */
 404
 405             if (idx+2 > p->size)
 406                 return -1;
 407
 408             label_ptr = ((unsigned) (AVAHI_DNS_PACKET_DATA(p)[idx] & ~0xC0)) << 8 | AVAHI_DNS_PACKET_DATA(p)[idx+1];
 409
 410             if ((label_ptr < AVAHI_DNS_PACKET_HEADER_SIZE) || (label_ptr >= idx))
 411                 return -1;
 412
 413             idx = label_ptr;
 414
 415             if (!compressed)
 416                 ret += 2;
 417
 418             compressed = 1;
 419         } else
 420             return -1;
 421     }
 422
 423     return -1;
 424 }
 425
 426 int avahi_dns_packet_consume_name(AvahiDnsPacket *p, char *ret_name, size_t l) {
 427     int r;
 428
 429     if ((r = consume_labels(p, p->rindex, ret_name, l)) < 0)
 430         return -1;
 431
 432     p->rindex += r;
 433     return 0;
 434 }
 435
 436 int avahi_dns_packet_consume_uint16(AvahiDnsPacket *p, uint16_t *ret_v) {
 437     uint8_t *d;
 438
 439     assert(p);
 440     assert(ret_v);
 441
 442     if (p->rindex + sizeof(uint16_t) > p->size)
 443         return -1;
 444
 445     d = (uint8_t*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex);
 446     *ret_v = (d[0] << 8) | d[1];
 447     p->rindex += sizeof(uint16_t);
 448
 449     return 0;
 450 }
 451
 452 int avahi_dns_packet_consume_uint32(AvahiDnsPacket *p, uint32_t *ret_v) {
 453     uint8_t* d;
 454
 455     assert(p);
 456     assert(ret_v);
 457
 458     if (p->rindex + sizeof(uint32_t) > p->size)
 459         return -1;
 460
 461     d = (uint8_t*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex);
 462     *ret_v = (d[0] << 24) | (d[1] << 16) | (d[2] << 8) | d[3];
 463     p->rindex += sizeof(uint32_t);
 464
 465     return 0;
 466 }
 467
 468 int avahi_dns_packet_consume_bytes(AvahiDnsPacket *p, void * ret_data, size_t l) {
 469     assert(p);
 470     assert(ret_data);
 471     assert(l > 0);
 472
 473     if (p->rindex + l > p->size)
 474         return -1;
 475
 476     memcpy(ret_data, AVAHI_DNS_PACKET_DATA(p) + p->rindex, l);
 477     p->rindex += l;
 478
 479     return 0;
 480 }
 481
 482 int avahi_dns_packet_consume_string(AvahiDnsPacket *p, char *ret_string, size_t l) {
 483     size_t k;
 484
 485     assert(p);
 486     assert(ret_string);
 487     assert(l > 0);
 488
 489     if (p->rindex >= p->size)
 490         return -1;
 491
 492     k = AVAHI_DNS_PACKET_DATA(p)[p->rindex];
 493
 494     if (p->rindex+1+k > p->size)
 495         return -1;
 496
 497     if (l > k+1)
 498         l = k+1;
 499
 500     memcpy(ret_string, AVAHI_DNS_PACKET_DATA(p)+p->rindex+1, l-1);
 501     ret_string[l-1] = 0;
 502
 503     p->rindex += 1+k;
 504
 505     return 0;
 506 }
 507
 508 const void* avahi_dns_packet_get_rptr(AvahiDnsPacket *p) {
 509     assert(p);
 510
 511     if (p->rindex > p->size)
 512         return NULL;
 513
 514     return AVAHI_DNS_PACKET_DATA(p) + p->rindex;
 515 }
 516
 517 int avahi_dns_packet_skip(AvahiDnsPacket *p, size_t length) {
 518     assert(p);
 519
 520     if (p->rindex + length > p->size)
 521         return -1;
 522
 523     p->rindex += length;
 524     return 0;
 525 }
 526
 527 static int parse_rdata(AvahiDnsPacket *p, AvahiRecord *r, uint16_t rdlength) {
 528     char buf[AVAHI_DOMAIN_NAME_MAX];
 529     const void* start;
 530
 531     assert(p);
 532     assert(r);
 533
 534     start = avahi_dns_packet_get_rptr(p);
 535
 536     switch (r->key->type) {
 537         case AVAHI_DNS_TYPE_PTR:
 538         case AVAHI_DNS_TYPE_CNAME:
 539         case AVAHI_DNS_TYPE_NS:
 540
 541             if (avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
 542                 return -1;
 543
 544             r->data.ptr.name = avahi_strdup(buf);
 545             break;
 546
 547
 548         case AVAHI_DNS_TYPE_SRV:
 549
 550             if (avahi_dns_packet_consume_uint16(p, &r->data.srv.priority) < 0 ||
 551                 avahi_dns_packet_consume_uint16(p, &r->data.srv.weight) < 0 ||
 552                 avahi_dns_packet_consume_uint16(p, &r->data.srv.port) < 0 ||
 553                 avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
 554                 return -1;
 555
 556             r->data.srv.name = avahi_strdup(buf);
 557             break;
 558
 559         case AVAHI_DNS_TYPE_HINFO:
 560
 561             if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
 562                 return -1;
 563
 564             r->data.hinfo.cpu = avahi_strdup(buf);
 565
 566             if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
 567                 return -1;
 568
 569             r->data.hinfo.os = avahi_strdup(buf);
 570             break;
 571
 572         case AVAHI_DNS_TYPE_TXT:
 573
 574             if (rdlength > 0) {
 575                 if (avahi_string_list_parse(avahi_dns_packet_get_rptr(p), rdlength, &r->data.txt.string_list) < 0)
 576                     return -1;
 577
 578                 if (avahi_dns_packet_skip(p, rdlength) < 0)
 579                     return -1;
 580             } else
 581                 r->data.txt.string_list = NULL;
 582
 583             break;
 584
 585         case AVAHI_DNS_TYPE_A:
 586
 587 /*             avahi_log_debug("A"); */
 588
 589             if (avahi_dns_packet_consume_bytes(p, &r->data.a.address, sizeof(AvahiIPv4Address)) < 0)
 590                 return -1;
 591
 592             break;
 593
 594         case AVAHI_DNS_TYPE_AAAA:
 595
 596 /*             avahi_log_debug("aaaa"); */
 597
 598             if (avahi_dns_packet_consume_bytes(p, &r->data.aaaa.address, sizeof(AvahiIPv6Address)) < 0)
 599                 return -1;
 600
 601             break;
 602
 603         default:
 604
 605 /*             avahi_log_debug("generic"); */
 606
 607             if (rdlength > 0) {
 608
 609                 r->data.generic.data = avahi_memdup(avahi_dns_packet_get_rptr(p), rdlength);
 610                 r->data.generic.size = rdlength;
 611
 612                 if (avahi_dns_packet_skip(p, rdlength) < 0)
 613                     return -1;
 614             }
 615
 616             break;
 617     }
 618
 619     /* Check if we read enough data */
 620     if ((const uint8_t*) avahi_dns_packet_get_rptr(p) - (const uint8_t*) start != rdlength)
 621         return -1;
 622
 623     return 0;
 624 }
 625
 626 AvahiRecord* avahi_dns_packet_consume_record(AvahiDnsPacket *p, int *ret_cache_flush) {
 627     char name[AVAHI_DOMAIN_NAME_MAX];
 628     uint16_t type, class;
 629     uint32_t ttl;
 630     uint16_t rdlength;
 631     AvahiRecord *r = NULL;
 632
 633     assert(p);
 634
 635     if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
 636         avahi_dns_packet_consume_uint16(p, &type) < 0 ||
 637         avahi_dns_packet_consume_uint16(p, &class) < 0 ||
 638         avahi_dns_packet_consume_uint32(p, &ttl) < 0 ||
 639         avahi_dns_packet_consume_uint16(p, &rdlength) < 0 ||
 640         p->rindex + rdlength > p->size)
 641         goto fail;
 642
 643     if (ret_cache_flush)
 644         *ret_cache_flush = !!(class & AVAHI_DNS_CACHE_FLUSH);
 645     class &= ~AVAHI_DNS_CACHE_FLUSH;
 646
 647     if (!(r = avahi_record_new_full(name, class, type, ttl)))
 648         goto fail;
 649
 650     if (parse_rdata(p, r, rdlength) < 0)
 651         goto fail;
 652
 653     if (!avahi_record_is_valid(r))
 654         goto fail;
 655
 656     return r;
 657
 658 fail:
 659     if (r)
 660         avahi_record_unref(r);
 661
 662     return NULL;
 663 }
 664
 665 AvahiKey* avahi_dns_packet_consume_key(AvahiDnsPacket *p, int *ret_unicast_response) {
 666     char name[256];
 667     uint16_t type, class;
 668     AvahiKey *k;
 669
 670     assert(p);
 671
 672     if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
 673         avahi_dns_packet_consume_uint16(p, &type) < 0 ||
 674         avahi_dns_packet_consume_uint16(p, &class) < 0)
 675         return NULL;
 676
 677     if (ret_unicast_response)
 678         *ret_unicast_response = !!(class & AVAHI_DNS_UNICAST_RESPONSE);
 679
 680     class &= ~AVAHI_DNS_UNICAST_RESPONSE;
 681
 682     if (!(k = avahi_key_new(name, class, type)))
 683         return NULL;
 684
 685     if (!avahi_key_is_valid(k)) {
 686         avahi_key_unref(k);
 687         return NULL;
 688     }
 689
 690     return k;
 691 }
 692
 693 uint8_t* avahi_dns_packet_append_key(AvahiDnsPacket *p, AvahiKey *k, int unicast_response) {
 694     uint8_t *t;
 695     size_t size;
 696
 697     assert(p);
 698     assert(k);
 699
 700     size = p->size;
 701
 702     if (!(t = avahi_dns_packet_append_name(p, k->name)) ||
 703         !avahi_dns_packet_append_uint16(p, k->type) ||
 704         !avahi_dns_packet_append_uint16(p, k->clazz | (unicast_response ? AVAHI_DNS_UNICAST_RESPONSE : 0))) {
 705         p->size = size;
 706         avahi_dns_packet_cleanup_name_table(p);
 707
 708         return NULL;
 709     }
 710
 711     return t;
 712 }
 713
 714 static int append_rdata(AvahiDnsPacket *p, AvahiRecord *r) {
 715     assert(p);
 716     assert(r);
 717
 718     switch (r->key->type) {
 719
 720         case AVAHI_DNS_TYPE_PTR:
 721         case AVAHI_DNS_TYPE_CNAME:
 722         case AVAHI_DNS_TYPE_NS:
 723
 724             if (!(avahi_dns_packet_append_name(p, r->data.ptr.name)))
 725                 return -1;
 726
 727             break;
 728
 729         case AVAHI_DNS_TYPE_SRV:
 730
 731             if (!avahi_dns_packet_append_uint16(p, r->data.srv.priority) ||
 732                 !avahi_dns_packet_append_uint16(p, r->data.srv.weight) ||
 733                 !avahi_dns_packet_append_uint16(p, r->data.srv.port) ||
 734                 !avahi_dns_packet_append_name(p, r->data.srv.name))
 735                 return -1;
 736
 737             break;
 738
 739         case AVAHI_DNS_TYPE_HINFO:
 740             if (!avahi_dns_packet_append_string(p, r->data.hinfo.cpu) ||
 741                 !avahi_dns_packet_append_string(p, r->data.hinfo.os))
 742                 return -1;
 743
 744             break;
 745
 746         case AVAHI_DNS_TYPE_TXT: {
 747
 748             uint8_t *data;
 749             size_t n;
 750
 751             n = avahi_string_list_serialize(r->data.txt.string_list, NULL, 0);
 752
 753             if (!(data = avahi_dns_packet_extend(p, n)))
 754                 return -1;
 755
 756             avahi_string_list_serialize(r->data.txt.string_list, data, n);
 757             break;
 758         }
 759
 760
 761         case AVAHI_DNS_TYPE_A:
 762
 763             if (!avahi_dns_packet_append_bytes(p, &r->data.a.address, sizeof(r->data.a.address)))
 764                 return -1;
 765
 766             break;
 767
 768         case AVAHI_DNS_TYPE_AAAA:
 769
 770             if (!avahi_dns_packet_append_bytes(p, &r->data.aaaa.address, sizeof(r->data.aaaa.address)))
 771                 return -1;
 772
 773             break;
 774
 775         default:
 776
 777             if (r->data.generic.size)
 778                 if (!avahi_dns_packet_append_bytes(p, r->data.generic.data, r->data.generic.size))
 779                     return -1;
 780
 781             break;
 782     }
 783
 784     return 0;
 785 }
 786
 787
 788 uint8_t* avahi_dns_packet_append_record(AvahiDnsPacket *p, AvahiRecord *r, int cache_flush, unsigned max_ttl) {
 789     uint8_t *t, *l, *start;
 790     size_t size;
 791
 792     assert(p);
 793     assert(r);
 794
 795     size = p->size;
 796
 797     if (!(t = avahi_dns_packet_append_name(p, r->key->name)) ||
 798         !avahi_dns_packet_append_uint16(p, r->key->type) ||
 799         !avahi_dns_packet_append_uint16(p, cache_flush ? (r->key->clazz | AVAHI_DNS_CACHE_FLUSH) : (r->key->clazz &~ AVAHI_DNS_CACHE_FLUSH)) ||
 800         !avahi_dns_packet_append_uint32(p, (max_ttl && r->ttl > max_ttl) ? max_ttl : r->ttl) ||
 801         !(l = avahi_dns_packet_append_uint16(p, 0)))
 802         goto fail;
 803
 804     start = avahi_dns_packet_extend(p, 0);
 805
 806     if (append_rdata(p, r) < 0)
 807         goto fail;
 808
 809     size = avahi_dns_packet_extend(p, 0) - start;
 810     assert(size <= AVAHI_DNS_RDATA_MAX);
 811
 812 /*     avahi_log_debug("appended %u", size); */
 813
 814     l[0] = (uint8_t) ((uint16_t) size >> 8);
 815     l[1] = (uint8_t) ((uint16_t) size);
 816
 817     return t;
 818
 819
 820 fail:
 821     p->size = size;
 822     avahi_dns_packet_cleanup_name_table(p);
 823
 824     return NULL;
 825 }
 826
 827 int avahi_dns_packet_is_empty(AvahiDnsPacket *p) {
 828     assert(p);
 829
 830     return p->size <= AVAHI_DNS_PACKET_HEADER_SIZE;
 831 }
 832
 833 size_t avahi_dns_packet_space(AvahiDnsPacket *p) {
 834     assert(p);
 835
 836     assert(p->size <= p->max_size);
 837
 838     return p->max_size - p->size;
 839 }
 840
 841 int avahi_rdata_parse(AvahiRecord *record, const void* rdata, size_t size) {
 842     int ret;
 843     AvahiDnsPacket p;
 844
 845     assert(record);
 846     assert(rdata);
 847
 848     p.data = (void*) rdata;
 849     p.max_size = p.size = size;
 850     p.rindex = 0;
 851     p.name_table = NULL;
 852
 853     ret = parse_rdata(&p, record, size);
 854
 855     assert(!p.name_table);
 856
 857     return ret;
 858 }
 859
 860 size_t avahi_rdata_serialize(AvahiRecord *record, void *rdata, size_t max_size) {
 861     int ret;
 862     AvahiDnsPacket p;
 863
 864     assert(record);
 865     assert(rdata);
 866     assert(max_size > 0);
 867
 868     p.data = (void*) rdata;
 869     p.max_size = max_size;
 870     p.size = p.rindex = 0;
 871     p.name_table = NULL;
 872
 873     ret = append_rdata(&p, record);
 874
 875     if (p.name_table)
 876          avahi_hashmap_free(p.name_table);
 877
 878     if (ret < 0)
 879         return (size_t) -1;
 880
 881     return p.size;
 882 }