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 <netinet/in.h>
  27
  28 #include <stdlib.h>
  29 #include <string.h>
  30 #include <stdio.h>
  31 #include <assert.h>
  32
  33 #include <avahi-common/domain.h>
  34 #include <avahi-common/malloc.h>
  35
  36 #include "dns.h"
  37 #include "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_MAX_SIZE;
  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
  60     memset(AVAHI_DNS_PACKET_DATA(p), 0, p->size);
  61     return p;
  62 }
  63
  64 AvahiDnsPacket* avahi_dns_packet_new_query(unsigned mtu) {
  65     AvahiDnsPacket *p;
  66
  67     if (!(p = avahi_dns_packet_new(mtu)))
  68         return NULL;
  69
  70     avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_FLAGS, AVAHI_DNS_FLAGS(0, 0, 0, 0, 0, 0, 0, 0, 0, 0));
  71     return p;
  72 }
  73
  74 AvahiDnsPacket* avahi_dns_packet_new_response(unsigned mtu, int aa) {
  75     AvahiDnsPacket *p;
  76
  77     if (!(p = avahi_dns_packet_new(mtu)))
  78         return NULL;
  79
  80     avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_FLAGS, AVAHI_DNS_FLAGS(1, 0, aa, 0, 0, 0, 0, 0, 0, 0));
  81     return p;
  82 }
  83
  84 AvahiDnsPacket* avahi_dns_packet_new_reply(AvahiDnsPacket* p, unsigned mtu, int copy_queries, int aa) {
  85     AvahiDnsPacket *r;
  86     assert(p);
  87
  88     if (!(r = avahi_dns_packet_new_response(mtu, aa)))
  89         return NULL;
  90
  91     if (copy_queries) {
  92         unsigned saved_rindex;
  93         uint32_t n;
  94
  95         saved_rindex = p->rindex;
  96         p->rindex = AVAHI_DNS_PACKET_HEADER_SIZE;
  97
  98         for (n = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_QDCOUNT); n > 0; n--) {
  99             AvahiKey *k;
 100             int unicast_response;
 101
 102             if ((k = avahi_dns_packet_consume_key(p, &unicast_response))) {
 103                 avahi_dns_packet_append_key(r, k, unicast_response);
 104                 avahi_key_unref(k);
 105             }
 106         }
 107
 108         p->rindex = saved_rindex;
 109
 110         avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_QDCOUNT, avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_QDCOUNT));
 111     }
 112
 113     avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_ID, avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_ID));
 114
 115     avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_FLAGS,
 116                                (avahi_dns_packet_get_field(r, AVAHI_DNS_FIELD_FLAGS) & ~AVAHI_DNS_FLAG_OPCODE) |
 117                                (avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) & AVAHI_DNS_FLAG_OPCODE));
 118
 119     return r;
 120 }
 121
 122
 123 void avahi_dns_packet_free(AvahiDnsPacket *p) {
 124     assert(p);
 125
 126     if (p->name_table)
 127         avahi_hashmap_free(p->name_table);
 128
 129     avahi_free(p);
 130 }
 131
 132 void avahi_dns_packet_set_field(AvahiDnsPacket *p, unsigned idx, uint16_t v) {
 133     assert(p);
 134     assert(idx < AVAHI_DNS_PACKET_HEADER_SIZE);
 135
 136     ((uint16_t*) AVAHI_DNS_PACKET_DATA(p))[idx] = htons(v);
 137 }
 138
 139 uint16_t avahi_dns_packet_get_field(AvahiDnsPacket *p, unsigned idx) {
 140     assert(p);
 141     assert(idx < AVAHI_DNS_PACKET_HEADER_SIZE);
 142
 143     return ntohs(((uint16_t*) AVAHI_DNS_PACKET_DATA(p))[idx]);
 144 }
 145
 146 void avahi_dns_packet_inc_field(AvahiDnsPacket *p, unsigned idx) {
 147     assert(p);
 148     assert(idx < AVAHI_DNS_PACKET_HEADER_SIZE);
 149
 150     avahi_dns_packet_set_field(p, idx, avahi_dns_packet_get_field(p, idx) + 1);
 151 }
 152
 153 uint8_t* avahi_dns_packet_append_name(AvahiDnsPacket *p, const char *name) {
 154     uint8_t *d, *saved_ptr = NULL;
 155     size_t saved_size;
 156
 157     assert(p);
 158     assert(name);
 159
 160     saved_size = p->size;
 161     saved_ptr = avahi_dns_packet_extend(p, 0);
 162
 163     while (*name) {
 164         uint8_t* prev;
 165         const char *pname;
 166         char label[64], *u;
 167
 168
 169         /* Check whether we can compress this name. */
 170
 171         if (p->name_table && (prev = avahi_hashmap_lookup(p->name_table, name))) {
 172             unsigned idx;
 173
 174             assert(prev >= AVAHI_DNS_PACKET_DATA(p));
 175             idx = (unsigned) (prev - AVAHI_DNS_PACKET_DATA(p));
 176
 177             assert(idx < p->size);
 178
 179             if (idx < 0x4000) {
 180                 uint16_t *t;
 181                 if (!(t = (uint16_t*) avahi_dns_packet_extend(p, sizeof(uint16_t))))
 182                     return NULL;
 183
 184                 *t = htons((0xC000 | idx));
 185                 return saved_ptr;
 186             }
 187         }
 188
 189         pname = name;
 190
 191         if (!(avahi_unescape_label(&name, label, sizeof(label))))
 192             goto fail;
 193
 194         if (!(d = avahi_dns_packet_append_string(p, label)))
 195             goto fail;
 196
 197         if (!p->name_table)
 198             /* This works only for normalized domain names */
 199             p->name_table = avahi_hashmap_new(avahi_string_hash, avahi_string_equal, avahi_free, NULL);
 200
 201         if (!(u = avahi_strdup(pname)))
 202             avahi_log_error("avahi_strdup() failed.");
 203         else
 204             avahi_hashmap_insert(p->name_table, u, d);
 205     }
 206
 207     if (!(d = avahi_dns_packet_extend(p, 1)))
 208         goto fail;
 209
 210     *d = 0;
 211
 212     return saved_ptr;
 213
 214 fail:
 215     p->size = saved_size;
 216     return NULL;
 217 }
 218
 219 uint8_t* avahi_dns_packet_append_uint16(AvahiDnsPacket *p, uint16_t v) {
 220     uint8_t *d;
 221     assert(p);
 222
 223     if (!(d = avahi_dns_packet_extend(p, sizeof(uint16_t))))
 224         return NULL;
 225
 226     *((uint16_t*) d) = htons(v);
 227     return d;
 228 }
 229
 230 uint8_t *avahi_dns_packet_append_uint32(AvahiDnsPacket *p, uint32_t v) {
 231     uint8_t *d;
 232     assert(p);
 233
 234     if (!(d = avahi_dns_packet_extend(p, sizeof(uint32_t))))
 235         return NULL;
 236
 237     *((uint32_t*) d) = htonl(v);
 238
 239     return d;
 240 }
 241
 242 uint8_t *avahi_dns_packet_append_bytes(AvahiDnsPacket  *p, const void *b, size_t l) {
 243     uint8_t* d;
 244
 245     assert(p);
 246     assert(b);
 247     assert(l);
 248
 249     if (!(d = avahi_dns_packet_extend(p, l)))
 250         return NULL;
 251
 252     memcpy(d, b, l);
 253     return d;
 254 }
 255
 256 uint8_t* avahi_dns_packet_append_string(AvahiDnsPacket *p, const char *s) {
 257     uint8_t* d;
 258     size_t k;
 259
 260     assert(p);
 261     assert(s);
 262
 263     if ((k = strlen(s)) >= 255)
 264         k = 255;
 265
 266     if (!(d = avahi_dns_packet_extend(p, k+1)))
 267         return NULL;
 268
 269     *d = (uint8_t) k;
 270     memcpy(d+1, s, k);
 271
 272     return d;
 273 }
 274
 275 uint8_t *avahi_dns_packet_extend(AvahiDnsPacket *p, size_t l) {
 276     uint8_t *d;
 277
 278     assert(p);
 279
 280     if (p->size+l > p->max_size)
 281         return NULL;
 282
 283     d = AVAHI_DNS_PACKET_DATA(p) + p->size;
 284     p->size += l;
 285
 286     return d;
 287 }
 288
 289 int avahi_dns_packet_is_valid(AvahiDnsPacket *p) {
 290     uint16_t flags;
 291     assert(p);
 292
 293     if (p->size < 12)
 294         return -1;
 295
 296     flags = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS);
 297
 298     if (flags & AVAHI_DNS_FLAG_OPCODE || flags & AVAHI_DNS_FLAG_RCODE)
 299         return -1;
 300
 301     return 0;
 302 }
 303
 304 int avahi_dns_packet_is_query(AvahiDnsPacket *p) {
 305     assert(p);
 306
 307     return !(avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) & AVAHI_DNS_FLAG_QR);
 308 }
 309
 310 static int consume_labels(AvahiDnsPacket *p, unsigned idx, char *ret_name, size_t l) {
 311     int ret = 0;
 312     int compressed = 0;
 313     int first_label = 1;
 314     assert(p && ret_name && l);
 315
 316     for (;;) {
 317         uint8_t n;
 318
 319         if (idx+1 > p->size)
 320             return -1;
 321
 322         n = AVAHI_DNS_PACKET_DATA(p)[idx];
 323
 324         if (!n) {
 325             idx++;
 326             if (!compressed)
 327                 ret++;
 328
 329             if (l < 1)
 330                 return -1;
 331             *ret_name = 0;
 332
 333             return ret;
 334
 335         } else if (n <= 63) {
 336             /* Uncompressed label */
 337             idx++;
 338             if (!compressed)
 339                 ret++;
 340
 341             if (idx + n > p->size)
 342                 return -1;
 343
 344             if ((size_t) n + 1 > l)
 345                 return -1;
 346
 347             if (!first_label) {
 348                 *(ret_name++) = '.';
 349                 l--;
 350             } else
 351                 first_label = 0;
 352
 353             if (!(avahi_escape_label(AVAHI_DNS_PACKET_DATA(p) + idx, n, &ret_name, &l)))
 354                 return -1;
 355
 356             idx += n;
 357
 358             if (!compressed)
 359                 ret += n;
 360         } else if ((n & 0xC0) == 0xC0) {
 361             /* Compressed label */
 362
 363             if (idx+2 > p->size)
 364                 return -1;
 365
 366             idx = ((unsigned) (AVAHI_DNS_PACKET_DATA(p)[idx] & ~0xC0)) << 8 | AVAHI_DNS_PACKET_DATA(p)[idx+1];
 367
 368             if (!compressed)
 369                 ret += 2;
 370
 371             compressed = 1;
 372         } else
 373             return -1;
 374     }
 375 }
 376
 377 int avahi_dns_packet_consume_name(AvahiDnsPacket *p, char *ret_name, size_t l) {
 378     int r;
 379
 380     if ((r = consume_labels(p, p->rindex, ret_name, l)) < 0)
 381         return -1;
 382
 383     p->rindex += r;
 384     return 0;
 385 }
 386
 387 int avahi_dns_packet_consume_uint16(AvahiDnsPacket *p, uint16_t *ret_v) {
 388     assert(p);
 389     assert(ret_v);
 390
 391     if (p->rindex + sizeof(uint16_t) > p->size)
 392         return -1;
 393
 394     *ret_v = ntohs(*((uint16_t*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex)));
 395     p->rindex += sizeof(uint16_t);
 396
 397     return 0;
 398 }
 399
 400 int avahi_dns_packet_consume_uint32(AvahiDnsPacket *p, uint32_t *ret_v) {
 401     assert(p);
 402     assert(ret_v);
 403
 404     if (p->rindex + sizeof(uint32_t) > p->size)
 405         return -1;
 406
 407     *ret_v = ntohl(*((uint32_t*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex)));
 408     p->rindex += sizeof(uint32_t);
 409
 410     return 0;
 411 }
 412
 413 int avahi_dns_packet_consume_bytes(AvahiDnsPacket *p, void * ret_data, size_t l) {
 414     assert(p);
 415     assert(ret_data);
 416     assert(l > 0);
 417
 418     if (p->rindex + l > p->size)
 419         return -1;
 420
 421     memcpy(ret_data, AVAHI_DNS_PACKET_DATA(p) + p->rindex, l);
 422     p->rindex += l;
 423
 424     return 0;
 425 }
 426
 427 int avahi_dns_packet_consume_string(AvahiDnsPacket *p, char *ret_string, size_t l) {
 428     size_t k;
 429
 430     assert(p);
 431     assert(ret_string);
 432     assert(l > 0);
 433
 434     if (p->rindex >= p->size)
 435         return -1;
 436
 437     k = AVAHI_DNS_PACKET_DATA(p)[p->rindex];
 438
 439     if (p->rindex+1+k > p->size)
 440         return -1;
 441
 442     if (l > k+1)
 443         l = k+1;
 444
 445     memcpy(ret_string, AVAHI_DNS_PACKET_DATA(p)+p->rindex+1, l-1);
 446     ret_string[l-1] = 0;
 447
 448     p->rindex += 1+k;
 449
 450     return 0;
 451 }
 452
 453 const void* avahi_dns_packet_get_rptr(AvahiDnsPacket *p) {
 454     assert(p);
 455
 456     if (p->rindex > p->size)
 457         return NULL;
 458
 459     return AVAHI_DNS_PACKET_DATA(p) + p->rindex;
 460 }
 461
 462 int avahi_dns_packet_skip(AvahiDnsPacket *p, size_t length) {
 463     assert(p);
 464
 465     if (p->rindex + length > p->size)
 466         return -1;
 467
 468     p->rindex += length;
 469     return 0;
 470 }
 471
 472 AvahiRecord* avahi_dns_packet_consume_record(AvahiDnsPacket *p, int *ret_cache_flush) {
 473     char name[257], buf[257];
 474     uint16_t type, class;
 475     uint32_t ttl;
 476     uint16_t rdlength;
 477     AvahiRecord *r = NULL;
 478     const void* start;
 479
 480     assert(p);
 481     assert(ret_cache_flush);
 482
 483 /*     avahi_log_debug("consume_record()"); */
 484
 485     if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
 486         avahi_dns_packet_consume_uint16(p, &type) < 0 ||
 487         avahi_dns_packet_consume_uint16(p, &class) < 0 ||
 488         avahi_dns_packet_consume_uint32(p, &ttl) < 0 ||
 489         avahi_dns_packet_consume_uint16(p, &rdlength) < 0 ||
 490         p->rindex + rdlength > p->size)
 491         goto fail;
 492
 493 /*     avahi_log_debug("name = %s, rdlength = %u", name, rdlength); */
 494
 495     *ret_cache_flush = !!(class & AVAHI_DNS_CACHE_FLUSH);
 496     class &= ~AVAHI_DNS_CACHE_FLUSH;
 497
 498     start = avahi_dns_packet_get_rptr(p);
 499
 500     if (!(r = avahi_record_new_full(name, class, type, ttl)))
 501         return NULL;
 502
 503     switch (type) {
 504         case AVAHI_DNS_TYPE_PTR:
 505         case AVAHI_DNS_TYPE_CNAME:
 506
 507 /*             avahi_log_debug("ptr"); */
 508
 509             if (avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
 510                 goto fail;
 511
 512             r->data.ptr.name = avahi_strdup(buf);
 513             break;
 514
 515
 516         case AVAHI_DNS_TYPE_SRV:
 517
 518 /*             avahi_log_debug("srv"); */
 519
 520             if (avahi_dns_packet_consume_uint16(p, &r->data.srv.priority) < 0 ||
 521                 avahi_dns_packet_consume_uint16(p, &r->data.srv.weight) < 0 ||
 522                 avahi_dns_packet_consume_uint16(p, &r->data.srv.port) < 0 ||
 523                 avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
 524                 goto fail;
 525
 526             r->data.srv.name = avahi_strdup(buf);
 527             break;
 528
 529         case AVAHI_DNS_TYPE_HINFO:
 530
 531 /*             avahi_log_debug("hinfo"); */
 532
 533             if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
 534                 goto fail;
 535
 536             r->data.hinfo.cpu = avahi_strdup(buf);
 537
 538             if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
 539                 goto fail;
 540
 541             r->data.hinfo.os = avahi_strdup(buf);
 542             break;
 543
 544         case AVAHI_DNS_TYPE_TXT:
 545
 546 /*             avahi_log_debug("txt"); */
 547
 548             if (rdlength > 0) {
 549                 r->data.txt.string_list = avahi_string_list_parse(avahi_dns_packet_get_rptr(p), rdlength);
 550
 551                 if (avahi_dns_packet_skip(p, rdlength) < 0)
 552                     goto fail;
 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                 goto fail;
 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                 goto fail;
 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                     goto fail;
 586             }
 587
 588             break;
 589     }
 590
 591 /*     avahi_log_debug("%i == %u ?", (uint8_t*) avahi_dns_packet_get_rptr(p) - (uint8_t*) start, rdlength); */
 592
 593     /* Check if we read enough data */
 594     if ((const uint8_t*) avahi_dns_packet_get_rptr(p) - (const uint8_t*) start != rdlength)
 595         goto fail;
 596
 597     return r;
 598
 599 fail:
 600     if (r)
 601         avahi_record_unref(r);
 602
 603     return NULL;
 604 }
 605
 606 AvahiKey* avahi_dns_packet_consume_key(AvahiDnsPacket *p, int *ret_unicast_response) {
 607     char name[256];
 608     uint16_t type, class;
 609
 610     assert(p);
 611     assert(ret_unicast_response);
 612
 613     if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
 614         avahi_dns_packet_consume_uint16(p, &type) < 0 ||
 615         avahi_dns_packet_consume_uint16(p, &class) < 0)
 616         return NULL;
 617
 618     *ret_unicast_response = !!(class & AVAHI_DNS_UNICAST_RESPONSE);
 619     class &= ~AVAHI_DNS_UNICAST_RESPONSE;
 620
 621     return avahi_key_new(name, class, type);
 622 }
 623
 624 uint8_t* avahi_dns_packet_append_key(AvahiDnsPacket *p, AvahiKey *k, int unicast_response) {
 625     uint8_t *t;
 626     size_t size;
 627
 628     assert(p);
 629     assert(k);
 630
 631     size = p->size;
 632
 633     if (!(t = avahi_dns_packet_append_name(p, k->name)) ||
 634         !avahi_dns_packet_append_uint16(p, k->type) ||
 635         !avahi_dns_packet_append_uint16(p, k->clazz | (unicast_response ? AVAHI_DNS_UNICAST_RESPONSE : 0))) {
 636         p->size = size;
 637         return NULL;
 638     }
 639
 640     return t;
 641 }
 642
 643 uint8_t* avahi_dns_packet_append_record(AvahiDnsPacket *p, AvahiRecord *r, int cache_flush, unsigned max_ttl) {
 644     uint8_t *t, *l, *start;
 645     size_t size;
 646
 647     assert(p);
 648     assert(r);
 649
 650     size = p->size;
 651
 652     if (!(t = avahi_dns_packet_append_name(p, r->key->name)) ||
 653         !avahi_dns_packet_append_uint16(p, r->key->type) ||
 654         !avahi_dns_packet_append_uint16(p, cache_flush ? (r->key->clazz | AVAHI_DNS_CACHE_FLUSH) : (r->key->clazz &~ AVAHI_DNS_CACHE_FLUSH)) ||
 655         !avahi_dns_packet_append_uint32(p, (max_ttl && r->ttl > max_ttl) ? max_ttl : r->ttl) ||
 656         !(l = avahi_dns_packet_append_uint16(p, 0)))
 657         goto fail;
 658
 659     start = avahi_dns_packet_extend(p, 0);
 660
 661     switch (r->key->type) {
 662
 663         case AVAHI_DNS_TYPE_PTR:
 664         case AVAHI_DNS_TYPE_CNAME :
 665
 666             if (!(avahi_dns_packet_append_name(p, r->data.ptr.name)))
 667                 goto fail;
 668
 669             break;
 670
 671         case AVAHI_DNS_TYPE_SRV:
 672
 673             if (!avahi_dns_packet_append_uint16(p, r->data.srv.priority) ||
 674                 !avahi_dns_packet_append_uint16(p, r->data.srv.weight) ||
 675                 !avahi_dns_packet_append_uint16(p, r->data.srv.port) ||
 676                 !avahi_dns_packet_append_name(p, r->data.srv.name))
 677                 goto fail;
 678
 679             break;
 680
 681         case AVAHI_DNS_TYPE_HINFO:
 682             if (!avahi_dns_packet_append_string(p, r->data.hinfo.cpu) ||
 683                 !avahi_dns_packet_append_string(p, r->data.hinfo.os))
 684                 goto fail;
 685
 686             break;
 687
 688         case AVAHI_DNS_TYPE_TXT: {
 689
 690             uint8_t *data;
 691             size_t n;
 692
 693             n = avahi_string_list_serialize(r->data.txt.string_list, NULL, 0);
 694
 695 /*             avahi_log_debug("appending string: %u %p", n, r->data.txt.string_list); */
 696
 697             if (!(data = avahi_dns_packet_extend(p, n)))
 698                 goto fail;
 699
 700             avahi_string_list_serialize(r->data.txt.string_list, data, n);
 701             break;
 702         }
 703
 704
 705         case AVAHI_DNS_TYPE_A:
 706
 707             if (!avahi_dns_packet_append_bytes(p, &r->data.a.address, sizeof(r->data.a.address)))
 708                 goto fail;
 709
 710             break;
 711
 712         case AVAHI_DNS_TYPE_AAAA:
 713
 714             if (!avahi_dns_packet_append_bytes(p, &r->data.aaaa.address, sizeof(r->data.aaaa.address)))
 715                 goto fail;
 716
 717             break;
 718
 719         default:
 720
 721             if (r->data.generic.size &&
 722                 avahi_dns_packet_append_bytes(p, r->data.generic.data, r->data.generic.size))
 723                 goto fail;
 724
 725             break;
 726     }
 727
 728
 729
 730
 731     size = avahi_dns_packet_extend(p, 0) - start;
 732     assert(size <= 0xFFFF);
 733
 734 /*     avahi_log_debug("appended %u", size); */
 735
 736     * (uint16_t*) l = htons((uint16_t) size);
 737
 738     return t;
 739
 740
 741 fail:
 742     p->size = size;
 743     return NULL;
 744 }
 745
 746 int avahi_dns_packet_is_empty(AvahiDnsPacket *p) {
 747     assert(p);
 748
 749     return p->size <= AVAHI_DNS_PACKET_HEADER_SIZE;
 750 }
 751
 752 size_t avahi_dns_packet_space(AvahiDnsPacket *p) {
 753     assert(p);
 754
 755     assert(p->size <= p->max_size);
 756
 757     return p->max_size - p->size;
 758 }