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