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