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 name_table_cleanup(void *key, void *value, void *user_data) {
 158     AvahiDnsPacket *p = user_data;
 159
 160     if ((uint8_t*) value >= AVAHI_DNS_PACKET_DATA(p) + p->size)
 161         avahi_hashmap_remove(p->name_table, key);
 162 }
 163
 164 void avahi_dns_packet_cleanup_name_table(AvahiDnsPacket *p) {
 165     if (p->name_table)
 166         avahi_hashmap_foreach(p->name_table, name_table_cleanup, p);
 167 }
 168
 169 uint8_t* avahi_dns_packet_append_name(AvahiDnsPacket *p, const char *name) {
 170     uint8_t *d, *saved_ptr = NULL;
 171     size_t saved_size;
 172
 173     assert(p);
 174     assert(name);
 175
 176     saved_size = p->size;
 177     saved_ptr = avahi_dns_packet_extend(p, 0);
 178
 179     while (*name) {
 180         uint8_t* prev;
 181         const char *pname;
 182         char label[64], *u;
 183
 184         /* Check whether we can compress this name. */
 185
 186         if (p->name_table && (prev = avahi_hashmap_lookup(p->name_table, name))) {
 187             unsigned idx;
 188
 189             assert(prev >= AVAHI_DNS_PACKET_DATA(p));
 190             idx = (unsigned) (prev - AVAHI_DNS_PACKET_DATA(p));
 191
 192             assert(idx < p->size);
 193
 194             if (idx < 0x4000) {
 195                 uint8_t *t;
 196                 if (!(t = (uint8_t*) avahi_dns_packet_extend(p, sizeof(uint16_t))))
 197                     return NULL;
 198
 199                 t[0] = (uint8_t) ((0xC000 | idx) >> 8);
 200                 t[1] = (uint8_t) idx;
 201                 return saved_ptr;
 202             }
 203         }
 204
 205         pname = name;
 206
 207         if (!(avahi_unescape_label(&name, label, sizeof(label))))
 208             goto fail;
 209
 210         if (!(d = avahi_dns_packet_append_string(p, label)))
 211             goto fail;
 212
 213         if (!p->name_table)
 214             /* This works only for normalized domain names */
 215             p->name_table = avahi_hashmap_new(avahi_string_hash, avahi_string_equal, avahi_free, NULL);
 216
 217         if (!(u = avahi_strdup(pname)))
 218             avahi_log_error("avahi_strdup() failed.");
 219         else
 220             avahi_hashmap_insert(p->name_table, u, d);
 221     }
 222
 223     if (!(d = avahi_dns_packet_extend(p, 1)))
 224         goto fail;
 225
 226     *d = 0;
 227
 228     return saved_ptr;
 229
 230 fail:
 231     p->size = saved_size;
 232     avahi_dns_packet_cleanup_name_table(p);
 233
 234     return NULL;
 235 }
 236
 237 uint8_t* avahi_dns_packet_append_uint16(AvahiDnsPacket *p, uint16_t v) {
 238     uint8_t *d;
 239     assert(p);
 240
 241     if (!(d = avahi_dns_packet_extend(p, sizeof(uint16_t))))
 242         return NULL;
 243
 244     d[0] = (uint8_t) (v >> 8);
 245     d[1] = (uint8_t) v;
 246     return d;
 247 }
 248
 249 uint8_t *avahi_dns_packet_append_uint32(AvahiDnsPacket *p, uint32_t v) {
 250     uint8_t *d;
 251     assert(p);
 252
 253     if (!(d = avahi_dns_packet_extend(p, sizeof(uint32_t))))
 254         return NULL;
 255
 256     d[0] = (uint8_t) (v >> 24);
 257     d[1] = (uint8_t) (v >> 16);
 258     d[2] = (uint8_t) (v >> 8);
 259     d[3] = (uint8_t) v;
 260
 261     return d;
 262 }
 263
 264 uint8_t *avahi_dns_packet_append_bytes(AvahiDnsPacket  *p, const void *b, size_t l) {
 265     uint8_t* d;
 266
 267     assert(p);
 268     assert(b);
 269     assert(l);
 270
 271     if (!(d = avahi_dns_packet_extend(p, l)))
 272         return NULL;
 273
 274     memcpy(d, b, l);
 275     return d;
 276 }
 277
 278 uint8_t* avahi_dns_packet_append_string(AvahiDnsPacket *p, const char *s) {
 279     uint8_t* d;
 280     size_t k;
 281
 282     assert(p);
 283     assert(s);
 284
 285     if ((k = strlen(s)) >= 255)
 286         k = 255;
 287
 288     if (!(d = avahi_dns_packet_extend(p, k+1)))
 289         return NULL;
 290
 291     *d = (uint8_t) k;
 292     memcpy(d+1, s, k);
 293
 294     return d;
 295 }
 296
 297 uint8_t *avahi_dns_packet_extend(AvahiDnsPacket *p, size_t l) {
 298     uint8_t *d;
 299
 300     assert(p);
 301
 302     if (p->size+l > p->max_size)
 303         return NULL;
 304
 305     d = AVAHI_DNS_PACKET_DATA(p) + p->size;
 306     p->size += l;
 307
 308     return d;
 309 }
 310
 311 int avahi_dns_packet_check_valid(AvahiDnsPacket *p) {
 312     uint16_t flags;
 313     assert(p);
 314
 315     if (p->size < AVAHI_DNS_PACKET_HEADER_SIZE)
 316         return -1;
 317
 318     flags = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS);
 319
 320     if (flags & AVAHI_DNS_FLAG_OPCODE)
 321         return -1;
 322
 323     return 0;
 324 }
 325
 326 int avahi_dns_packet_check_valid_multicast(AvahiDnsPacket *p) {
 327     uint16_t flags;
 328     assert(p);
 329
 330     if (avahi_dns_packet_check_valid(p) < 0)
 331         return -1;
 332
 333     flags = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS);
 334
 335     if (flags & AVAHI_DNS_FLAG_RCODE)
 336         return -1;
 337
 338     return 0;
 339 }
 340
 341 int avahi_dns_packet_is_query(AvahiDnsPacket *p) {
 342     assert(p);
 343
 344     return !(avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) & AVAHI_DNS_FLAG_QR);
 345 }
 346
 347 static int consume_labels(AvahiDnsPacket *p, unsigned idx, char *ret_name, size_t l) {
 348     int ret = 0;
 349     int compressed = 0;
 350     int first_label = 1;
 351     unsigned label_ptr;
 352     int i;
 353     assert(p && ret_name && l);
 354
 355     for (i = 0; i < AVAHI_DNS_LABELS_MAX; i++) {
 356         uint8_t n;
 357
 358         if (idx+1 > p->size)
 359             return -1;
 360
 361         n = AVAHI_DNS_PACKET_DATA(p)[idx];
 362
 363         if (!n) {
 364             idx++;
 365             if (!compressed)
 366                 ret++;
 367
 368             if (l < 1)
 369                 return -1;
 370             *ret_name = 0;
 371
 372             return ret;
 373
 374         } else if (n <= 63) {
 375             /* Uncompressed label */
 376             idx++;
 377             if (!compressed)
 378                 ret++;
 379
 380             if (idx + n > p->size)
 381                 return -1;
 382
 383             if ((size_t) n + 1 > l)
 384                 return -1;
 385
 386             if (!first_label) {
 387                 *(ret_name++) = '.';
 388                 l--;
 389             } else
 390                 first_label = 0;
 391
 392             if (!(avahi_escape_label((char*) AVAHI_DNS_PACKET_DATA(p) + idx, n, &ret_name, &l)))
 393                 return -1;
 394
 395             idx += n;
 396
 397             if (!compressed)
 398                 ret += n;
 399         } else if ((n & 0xC0) == 0xC0) {
 400             /* Compressed label */
 401
 402             if (idx+2 > p->size)
 403                 return -1;
 404
 405             label_ptr = ((unsigned) (AVAHI_DNS_PACKET_DATA(p)[idx] & ~0xC0)) << 8 | AVAHI_DNS_PACKET_DATA(p)[idx+1];
 406
 407             if ((label_ptr < AVAHI_DNS_PACKET_HEADER_SIZE) || (label_ptr >= idx))
 408                 return -1;
 409
 410             idx = label_ptr;
 411
 412             if (!compressed)
 413                 ret += 2;
 414
 415             compressed = 1;
 416         } else
 417             return -1;
 418     }
 419
 420     return -1;
 421 }
 422
 423 int avahi_dns_packet_consume_name(AvahiDnsPacket *p, char *ret_name, size_t l) {
 424     int r;
 425
 426     if ((r = consume_labels(p, p->rindex, ret_name, l)) < 0)
 427         return -1;
 428
 429     p->rindex += r;
 430     return 0;
 431 }
 432
 433 int avahi_dns_packet_consume_uint16(AvahiDnsPacket *p, uint16_t *ret_v) {
 434     uint8_t *d;
 435
 436     assert(p);
 437     assert(ret_v);
 438
 439     if (p->rindex + sizeof(uint16_t) > p->size)
 440         return -1;
 441
 442     d = (uint8_t*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex);
 443     *ret_v = (d[0] << 8) | d[1];
 444     p->rindex += sizeof(uint16_t);
 445
 446     return 0;
 447 }
 448
 449 int avahi_dns_packet_consume_uint32(AvahiDnsPacket *p, uint32_t *ret_v) {
 450     uint8_t* d;
 451
 452     assert(p);
 453     assert(ret_v);
 454
 455     if (p->rindex + sizeof(uint32_t) > p->size)
 456         return -1;
 457
 458     d = (uint8_t*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex);
 459     *ret_v = (d[0] << 24) | (d[1] << 16) | (d[2] << 8) | d[3];
 460     p->rindex += sizeof(uint32_t);
 461
 462     return 0;
 463 }
 464
 465 int avahi_dns_packet_consume_bytes(AvahiDnsPacket *p, void * ret_data, size_t l) {
 466     assert(p);
 467     assert(ret_data);
 468     assert(l > 0);
 469
 470     if (p->rindex + l > p->size)
 471         return -1;
 472
 473     memcpy(ret_data, AVAHI_DNS_PACKET_DATA(p) + p->rindex, l);
 474     p->rindex += l;
 475
 476     return 0;
 477 }
 478
 479 int avahi_dns_packet_consume_string(AvahiDnsPacket *p, char *ret_string, size_t l) {
 480     size_t k;
 481
 482     assert(p);
 483     assert(ret_string);
 484     assert(l > 0);
 485
 486     if (p->rindex >= p->size)
 487         return -1;
 488
 489     k = AVAHI_DNS_PACKET_DATA(p)[p->rindex];
 490
 491     if (p->rindex+1+k > p->size)
 492         return -1;
 493
 494     if (l > k+1)
 495         l = k+1;
 496
 497     memcpy(ret_string, AVAHI_DNS_PACKET_DATA(p)+p->rindex+1, l-1);
 498     ret_string[l-1] = 0;
 499
 500     p->rindex += 1+k;
 501
 502     return 0;
 503 }
 504
 505 const void* avahi_dns_packet_get_rptr(AvahiDnsPacket *p) {
 506     assert(p);
 507
 508     if (p->rindex > p->size)
 509         return NULL;
 510
 511     return AVAHI_DNS_PACKET_DATA(p) + p->rindex;
 512 }
 513
 514 int avahi_dns_packet_skip(AvahiDnsPacket *p, size_t length) {
 515     assert(p);
 516
 517     if (p->rindex + length > p->size)
 518         return -1;
 519
 520     p->rindex += length;
 521     return 0;
 522 }
 523
 524 static int parse_rdata(AvahiDnsPacket *p, AvahiRecord *r, uint16_t rdlength) {
 525     char buf[AVAHI_DOMAIN_NAME_MAX];
 526     const void* start;
 527
 528     assert(p);
 529     assert(r);
 530
 531     start = avahi_dns_packet_get_rptr(p);
 532
 533     switch (r->key->type) {
 534         case AVAHI_DNS_TYPE_PTR:
 535         case AVAHI_DNS_TYPE_CNAME:
 536         case AVAHI_DNS_TYPE_NS:
 537
 538             if (avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
 539                 return -1;
 540
 541             r->data.ptr.name = avahi_strdup(buf);
 542             break;
 543
 544
 545         case AVAHI_DNS_TYPE_SRV:
 546
 547             if (avahi_dns_packet_consume_uint16(p, &r->data.srv.priority) < 0 ||
 548                 avahi_dns_packet_consume_uint16(p, &r->data.srv.weight) < 0 ||
 549                 avahi_dns_packet_consume_uint16(p, &r->data.srv.port) < 0 ||
 550                 avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
 551                 return -1;
 552
 553             r->data.srv.name = avahi_strdup(buf);
 554             break;
 555
 556         case AVAHI_DNS_TYPE_HINFO:
 557
 558             if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
 559                 return -1;
 560
 561             r->data.hinfo.cpu = avahi_strdup(buf);
 562
 563             if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
 564                 return -1;
 565
 566             r->data.hinfo.os = avahi_strdup(buf);
 567             break;
 568
 569         case AVAHI_DNS_TYPE_TXT:
 570
 571             if (rdlength > 0) {
 572                 if (avahi_string_list_parse(avahi_dns_packet_get_rptr(p), rdlength, &r->data.txt.string_list) < 0)
 573                     return -1;
 574
 575                 if (avahi_dns_packet_skip(p, rdlength) < 0)
 576                     return -1;
 577             } else
 578                 r->data.txt.string_list = NULL;
 579
 580             break;
 581
 582         case AVAHI_DNS_TYPE_A:
 583
 584 /*             avahi_log_debug("A"); */
 585
 586             if (avahi_dns_packet_consume_bytes(p, &r->data.a.address, sizeof(AvahiIPv4Address)) < 0)
 587                 return -1;
 588
 589             break;
 590
 591         case AVAHI_DNS_TYPE_AAAA:
 592
 593 /*             avahi_log_debug("aaaa"); */
 594
 595             if (avahi_dns_packet_consume_bytes(p, &r->data.aaaa.address, sizeof(AvahiIPv6Address)) < 0)
 596                 return -1;
 597
 598             break;
 599
 600         default:
 601
 602 /*             avahi_log_debug("generic"); */
 603
 604             if (rdlength > 0) {
 605
 606                 r->data.generic.data = avahi_memdup(avahi_dns_packet_get_rptr(p), rdlength);
 607                 r->data.generic.size = rdlength;
 608
 609                 if (avahi_dns_packet_skip(p, rdlength) < 0)
 610                     return -1;
 611             }
 612
 613             break;
 614     }
 615
 616     /* Check if we read enough data */
 617     if ((const uint8_t*) avahi_dns_packet_get_rptr(p) - (const uint8_t*) start != rdlength)
 618         return -1;
 619
 620     return 0;
 621 }
 622
 623 AvahiRecord* avahi_dns_packet_consume_record(AvahiDnsPacket *p, int *ret_cache_flush) {
 624     char name[AVAHI_DOMAIN_NAME_MAX];
 625     uint16_t type, class;
 626     uint32_t ttl;
 627     uint16_t rdlength;
 628     AvahiRecord *r = NULL;
 629
 630     assert(p);
 631
 632     if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
 633         avahi_dns_packet_consume_uint16(p, &type) < 0 ||
 634         avahi_dns_packet_consume_uint16(p, &class) < 0 ||
 635         avahi_dns_packet_consume_uint32(p, &ttl) < 0 ||
 636         avahi_dns_packet_consume_uint16(p, &rdlength) < 0 ||
 637         p->rindex + rdlength > p->size)
 638         goto fail;
 639
 640     if (ret_cache_flush)
 641         *ret_cache_flush = !!(class & AVAHI_DNS_CACHE_FLUSH);
 642     class &= ~AVAHI_DNS_CACHE_FLUSH;
 643
 644     if (!(r = avahi_record_new_full(name, class, type, ttl)))
 645         goto fail;
 646
 647     if (parse_rdata(p, r, rdlength) < 0)
 648         goto fail;
 649
 650     if (!avahi_record_is_valid(r))
 651         goto fail;
 652
 653     return r;
 654
 655 fail:
 656     if (r)
 657         avahi_record_unref(r);
 658
 659     return NULL;
 660 }
 661
 662 AvahiKey* avahi_dns_packet_consume_key(AvahiDnsPacket *p, int *ret_unicast_response) {
 663     char name[256];
 664     uint16_t type, class;
 665     AvahiKey *k;
 666
 667     assert(p);
 668
 669     if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
 670         avahi_dns_packet_consume_uint16(p, &type) < 0 ||
 671         avahi_dns_packet_consume_uint16(p, &class) < 0)
 672         return NULL;
 673
 674     if (ret_unicast_response)
 675         *ret_unicast_response = !!(class & AVAHI_DNS_UNICAST_RESPONSE);
 676
 677     class &= ~AVAHI_DNS_UNICAST_RESPONSE;
 678
 679     if (!(k = avahi_key_new(name, class, type)))
 680         return NULL;
 681
 682     if (!avahi_key_is_valid(k)) {
 683         avahi_key_unref(k);
 684         return NULL;
 685     }
 686
 687     return k;
 688 }
 689
 690 uint8_t* avahi_dns_packet_append_key(AvahiDnsPacket *p, AvahiKey *k, int unicast_response) {
 691     uint8_t *t;
 692     size_t size;
 693
 694     assert(p);
 695     assert(k);
 696
 697     size = p->size;
 698
 699     if (!(t = avahi_dns_packet_append_name(p, k->name)) ||
 700         !avahi_dns_packet_append_uint16(p, k->type) ||
 701         !avahi_dns_packet_append_uint16(p, k->clazz | (unicast_response ? AVAHI_DNS_UNICAST_RESPONSE : 0))) {
 702         p->size = size;
 703         avahi_dns_packet_cleanup_name_table(p);
 704
 705         return NULL;
 706     }
 707
 708     return t;
 709 }
 710
 711 static int append_rdata(AvahiDnsPacket *p, AvahiRecord *r) {
 712     assert(p);
 713     assert(r);
 714
 715     switch (r->key->type) {
 716
 717         case AVAHI_DNS_TYPE_PTR:
 718         case AVAHI_DNS_TYPE_CNAME:
 719         case AVAHI_DNS_TYPE_NS:
 720
 721             if (!(avahi_dns_packet_append_name(p, r->data.ptr.name)))
 722                 return -1;
 723
 724             break;
 725
 726         case AVAHI_DNS_TYPE_SRV:
 727
 728             if (!avahi_dns_packet_append_uint16(p, r->data.srv.priority) ||
 729                 !avahi_dns_packet_append_uint16(p, r->data.srv.weight) ||
 730                 !avahi_dns_packet_append_uint16(p, r->data.srv.port) ||
 731                 !avahi_dns_packet_append_name(p, r->data.srv.name))
 732                 return -1;
 733
 734             break;
 735
 736         case AVAHI_DNS_TYPE_HINFO:
 737             if (!avahi_dns_packet_append_string(p, r->data.hinfo.cpu) ||
 738                 !avahi_dns_packet_append_string(p, r->data.hinfo.os))
 739                 return -1;
 740
 741             break;
 742
 743         case AVAHI_DNS_TYPE_TXT: {
 744
 745             uint8_t *data;
 746             size_t n;
 747
 748             n = avahi_string_list_serialize(r->data.txt.string_list, NULL, 0);
 749
 750             if (!(data = avahi_dns_packet_extend(p, n)))
 751                 return -1;
 752
 753             avahi_string_list_serialize(r->data.txt.string_list, data, n);
 754             break;
 755         }
 756
 757
 758         case AVAHI_DNS_TYPE_A:
 759
 760             if (!avahi_dns_packet_append_bytes(p, &r->data.a.address, sizeof(r->data.a.address)))
 761                 return -1;
 762
 763             break;
 764
 765         case AVAHI_DNS_TYPE_AAAA:
 766
 767             if (!avahi_dns_packet_append_bytes(p, &r->data.aaaa.address, sizeof(r->data.aaaa.address)))
 768                 return -1;
 769
 770             break;
 771
 772         default:
 773
 774             if (r->data.generic.size)
 775                 if (!avahi_dns_packet_append_bytes(p, r->data.generic.data, r->data.generic.size))
 776                     return -1;
 777
 778             break;
 779     }
 780
 781     return 0;
 782 }
 783
 784
 785 uint8_t* avahi_dns_packet_append_record(AvahiDnsPacket *p, AvahiRecord *r, int cache_flush, unsigned max_ttl) {
 786     uint8_t *t, *l, *start;
 787     size_t size;
 788
 789     assert(p);
 790     assert(r);
 791
 792     size = p->size;
 793
 794     if (!(t = avahi_dns_packet_append_name(p, r->key->name)) ||
 795         !avahi_dns_packet_append_uint16(p, r->key->type) ||
 796         !avahi_dns_packet_append_uint16(p, cache_flush ? (r->key->clazz | AVAHI_DNS_CACHE_FLUSH) : (r->key->clazz &~ AVAHI_DNS_CACHE_FLUSH)) ||
 797         !avahi_dns_packet_append_uint32(p, (max_ttl && r->ttl > max_ttl) ? max_ttl : r->ttl) ||
 798         !(l = avahi_dns_packet_append_uint16(p, 0)))
 799         goto fail;
 800
 801     start = avahi_dns_packet_extend(p, 0);
 802
 803     if (append_rdata(p, r) < 0)
 804         goto fail;
 805
 806     size = avahi_dns_packet_extend(p, 0) - start;
 807     assert(size <= AVAHI_DNS_RDATA_MAX);
 808
 809 /*     avahi_log_debug("appended %u", size); */
 810
 811     l[0] = (uint8_t) ((uint16_t) size >> 8);
 812     l[1] = (uint8_t) ((uint16_t) size);
 813
 814     return t;
 815
 816
 817 fail:
 818     p->size = size;
 819     avahi_dns_packet_cleanup_name_table(p);
 820
 821     return NULL;
 822 }
 823
 824 int avahi_dns_packet_is_empty(AvahiDnsPacket *p) {
 825     assert(p);
 826
 827     return p->size <= AVAHI_DNS_PACKET_HEADER_SIZE;
 828 }
 829
 830 size_t avahi_dns_packet_space(AvahiDnsPacket *p) {
 831     assert(p);
 832
 833     assert(p->size <= p->max_size);
 834
 835     return p->max_size - p->size;
 836 }
 837
 838 int avahi_rdata_parse(AvahiRecord *record, const void* rdata, size_t size) {
 839     int ret;
 840     AvahiDnsPacket p;
 841
 842     assert(record);
 843     assert(rdata);
 844
 845     p.data = (void*) rdata;
 846     p.max_size = p.size = size;
 847     p.rindex = 0;
 848     p.name_table = NULL;
 849
 850     ret = parse_rdata(&p, record, size);
 851
 852     assert(!p.name_table);
 853
 854     return ret;
 855 }
 856
 857 size_t avahi_rdata_serialize(AvahiRecord *record, void *rdata, size_t max_size) {
 858     int ret;
 859     AvahiDnsPacket p;
 860
 861     assert(record);
 862     assert(rdata);
 863     assert(max_size > 0);
 864
 865     p.data = (void*) rdata;
 866     p.max_size = max_size;
 867     p.size = p.rindex = 0;
 868     p.name_table = NULL;
 869
 870     ret = append_rdata(&p, record);
 871
 872     if (p.name_table)
 873          avahi_hashmap_free(p.name_table);
 874
 875     if (ret < 0)
 876         return (size_t) -1;
 877
 878     return p.size;
 879 }