git.meshlink.io Git - catta/blob - src/dns.c

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