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
  32 #include "dns.h"
  33 #include "util.h"
  34
  35 AvahiDnsPacket* avahi_dns_packet_new(guint mtu) {
  36     AvahiDnsPacket *p;
  37     guint max_size;
  38
  39     if (mtu <= 0)
  40         max_size = AVAHI_DNS_PACKET_MAX_SIZE;
  41     else if (mtu >= 48)
  42         max_size = mtu - 48;
  43     else
  44         max_size = 0;
  45
  46     if (max_size < AVAHI_DNS_PACKET_HEADER_SIZE)
  47         max_size = AVAHI_DNS_PACKET_HEADER_SIZE;
  48
  49     p = g_malloc(sizeof(AvahiDnsPacket) + max_size);
  50     p->size = p->rindex = AVAHI_DNS_PACKET_HEADER_SIZE;
  51     p->max_size = max_size;
  52     p->name_table = NULL;
  53
  54     memset(AVAHI_DNS_PACKET_DATA(p), 0, p->size);
  55     return p;
  56 }
  57
  58 AvahiDnsPacket* avahi_dns_packet_new_query(guint mtu) {
  59     AvahiDnsPacket *p;
  60
  61     p = avahi_dns_packet_new(mtu);
  62     avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_FLAGS, AVAHI_DNS_FLAGS(0, 0, 0, 0, 0, 0, 0, 0, 0, 0));
  63     return p;
  64 }
  65
  66 AvahiDnsPacket* avahi_dns_packet_new_response(guint mtu, gboolean aa) {
  67     AvahiDnsPacket *p;
  68
  69     p = avahi_dns_packet_new(mtu);
  70     avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_FLAGS, AVAHI_DNS_FLAGS(1, 0, aa, 0, 0, 0, 0, 0, 0, 0));
  71     return p;
  72 }
  73
  74 AvahiDnsPacket* avahi_dns_packet_new_reply(AvahiDnsPacket* p, guint mtu, gboolean copy_queries, gboolean aa) {
  75     AvahiDnsPacket *r;
  76     g_assert(p);
  77
  78     r = avahi_dns_packet_new_response(mtu, aa);
  79
  80     if (copy_queries) {
  81         guint n, saved_rindex;
  82
  83         saved_rindex = p->rindex;
  84         p->rindex = AVAHI_DNS_PACKET_HEADER_SIZE;
  85
  86         for (n = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_QDCOUNT); n > 0; n--) {
  87             AvahiKey *k;
  88             gboolean unicast_response;
  89
  90             if ((k = avahi_dns_packet_consume_key(p, &unicast_response))) {
  91                 avahi_dns_packet_append_key(r, k, unicast_response);
  92                 avahi_key_unref(k);
  93             }
  94         }
  95
  96         p->rindex = saved_rindex;
  97
  98         avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_QDCOUNT, avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_QDCOUNT));
  99     }
 100
 101     avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_ID, avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_ID));
 102
 103     avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_FLAGS,
 104                                (avahi_dns_packet_get_field(r, AVAHI_DNS_FIELD_FLAGS) & ~AVAHI_DNS_FLAG_OPCODE) |
 105                                (avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) & AVAHI_DNS_FLAG_OPCODE));
 106
 107     return r;
 108 }
 109
 110
 111 void avahi_dns_packet_free(AvahiDnsPacket *p) {
 112     g_assert(p);
 113
 114     if (p->name_table)
 115         g_hash_table_destroy(p->name_table);
 116
 117     g_free(p);
 118 }
 119
 120 void avahi_dns_packet_set_field(AvahiDnsPacket *p, guint index, guint16 v) {
 121     g_assert(p);
 122     g_assert(index < AVAHI_DNS_PACKET_HEADER_SIZE);
 123
 124     ((guint16*) AVAHI_DNS_PACKET_DATA(p))[index] = g_htons(v);
 125 }
 126
 127 guint16 avahi_dns_packet_get_field(AvahiDnsPacket *p, guint index) {
 128     g_assert(p);
 129     g_assert(index < AVAHI_DNS_PACKET_HEADER_SIZE);
 130
 131     return g_ntohs(((guint16*) AVAHI_DNS_PACKET_DATA(p))[index]);
 132 }
 133
 134 void avahi_dns_packet_inc_field(AvahiDnsPacket *p, guint index) {
 135     g_assert(p);
 136
 137     avahi_dns_packet_set_field(p, index, avahi_dns_packet_get_field(p, index) + 1);
 138 }
 139
 140 guint8* avahi_dns_packet_append_name(AvahiDnsPacket *p, const gchar *name) {
 141     guint8 *d, *saved_ptr = NULL;
 142     guint saved_size;
 143
 144     g_assert(p);
 145     g_assert(name);
 146
 147     saved_size = p->size;
 148     saved_ptr = avahi_dns_packet_extend(p, 0);
 149
 150     while (*name) {
 151         guint8* prev;
 152         const gchar *pname;
 153         gchar label[64];
 154
 155         /* Check whether we can compress this name. */
 156
 157         if (p->name_table && (prev = g_hash_table_lookup(p->name_table, name))) {
 158             guint index;
 159
 160             g_assert(prev >= AVAHI_DNS_PACKET_DATA(p));
 161             index = (guint) (prev - AVAHI_DNS_PACKET_DATA(p));
 162
 163             g_assert(index < p->size);
 164
 165             if (index < 0x4000) {
 166                 guint16 *t;
 167                 if (!(t = (guint16*) avahi_dns_packet_extend(p, sizeof(guint16))))
 168                     return NULL;
 169
 170                 *t = g_htons((0xC000 | index));
 171                 return saved_ptr;
 172             }
 173         }
 174
 175         pname = name;
 176
 177         if (!(avahi_unescape_label(&name, label, sizeof(label))))
 178             goto fail;
 179
 180         if (!(d = avahi_dns_packet_append_string(p, label)))
 181             goto fail;
 182
 183         if (!p->name_table)
 184             /* This works only for normalized domain names */
 185             p->name_table = g_hash_table_new_full((GHashFunc) g_str_hash, (GEqualFunc) g_str_equal, g_free, NULL);
 186
 187         g_hash_table_insert(p->name_table, g_strdup(pname), d);
 188     }
 189
 190     if (!(d = avahi_dns_packet_extend(p, 1)))
 191         goto fail;
 192
 193     *d = 0;
 194
 195     return saved_ptr;
 196
 197 fail:
 198     p->size = saved_size;
 199     return NULL;
 200 }
 201
 202 guint8* avahi_dns_packet_append_uint16(AvahiDnsPacket *p, guint16 v) {
 203     guint8 *d;
 204     g_assert(p);
 205
 206     if (!(d = avahi_dns_packet_extend(p, sizeof(guint16))))
 207         return NULL;
 208
 209     *((guint16*) d) = g_htons(v);
 210     return d;
 211 }
 212
 213 guint8 *avahi_dns_packet_append_uint32(AvahiDnsPacket *p, guint32 v) {
 214     guint8 *d;
 215     g_assert(p);
 216
 217     if (!(d = avahi_dns_packet_extend(p, sizeof(guint32))))
 218         return NULL;
 219
 220     *((guint32*) d) = g_htonl(v);
 221
 222     return d;
 223 }
 224
 225 guint8 *avahi_dns_packet_append_bytes(AvahiDnsPacket  *p, gconstpointer b, guint l) {
 226     guint8* d;
 227
 228     g_assert(p);
 229     g_assert(b);
 230     g_assert(l);
 231
 232     if (!(d = avahi_dns_packet_extend(p, l)))
 233         return NULL;
 234
 235     memcpy(d, b, l);
 236     return d;
 237 }
 238
 239 guint8* avahi_dns_packet_append_string(AvahiDnsPacket *p, const gchar *s) {
 240     guint8* d;
 241     guint k;
 242
 243     g_assert(p);
 244     g_assert(s);
 245
 246     if ((k = strlen(s)) >= 255)
 247         k = 255;
 248
 249     if (!(d = avahi_dns_packet_extend(p, k+1)))
 250         return NULL;
 251
 252     *d = (guint8) k;
 253     memcpy(d+1, s, k);
 254
 255     return d;
 256 }
 257
 258 guint8 *avahi_dns_packet_extend(AvahiDnsPacket *p, guint l) {
 259     guint8 *d;
 260
 261     g_assert(p);
 262
 263     if (p->size+l > p->max_size)
 264         return NULL;
 265
 266     d = AVAHI_DNS_PACKET_DATA(p) + p->size;
 267     p->size += l;
 268
 269     return d;
 270 }
 271
 272 gint avahi_dns_packet_check_valid(AvahiDnsPacket *p) {
 273     guint16 flags;
 274     g_assert(p);
 275
 276     if (p->size < 12)
 277         return -1;
 278
 279     flags = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS);
 280
 281     if (flags & AVAHI_DNS_FLAG_OPCODE || flags & AVAHI_DNS_FLAG_RCODE)
 282         return -1;
 283
 284     return 0;
 285 }
 286
 287 gint avahi_dns_packet_is_query(AvahiDnsPacket *p) {
 288     g_assert(p);
 289
 290     return !(avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) & AVAHI_DNS_FLAG_QR);
 291 }
 292
 293 static gint consume_labels(AvahiDnsPacket *p, guint index, gchar *ret_name, guint l) {
 294     gint ret = 0;
 295     int compressed = 0;
 296     int first_label = 1;
 297     g_assert(p && ret_name && l);
 298
 299     for (;;) {
 300         guint8 n;
 301
 302         if (index+1 > p->size)
 303             return -1;
 304
 305         n = AVAHI_DNS_PACKET_DATA(p)[index];
 306
 307         if (!n) {
 308             index++;
 309             if (!compressed)
 310                 ret++;
 311
 312             if (l < 1)
 313                 return -1;
 314             *ret_name = 0;
 315
 316             return ret;
 317
 318         } else if (n <= 63) {
 319             /* Uncompressed label */
 320             index++;
 321             if (!compressed)
 322                 ret++;
 323
 324             if (index + n > p->size)
 325                 return -1;
 326
 327             if ((guint) n + 1 > l)
 328                 return -1;
 329
 330             if (!first_label) {
 331                 *(ret_name++) = '.';
 332                 l--;
 333             } else
 334                 first_label = 0;
 335
 336             if (!(avahi_escape_label(AVAHI_DNS_PACKET_DATA(p) + index, n, &ret_name, &l)))
 337                 return -1;
 338
 339             index += n;
 340
 341             if (!compressed)
 342                 ret += n;
 343         } else if ((n & 0xC0) == 0xC0) {
 344             /* Compressed label */
 345
 346             if (index+2 > p->size)
 347                 return -1;
 348
 349             index = ((guint) (AVAHI_DNS_PACKET_DATA(p)[index] & ~0xC0)) << 8 | AVAHI_DNS_PACKET_DATA(p)[index+1];
 350
 351             if (!compressed)
 352                 ret += 2;
 353
 354             compressed = 1;
 355         } else
 356             return -1;
 357     }
 358 }
 359
 360 gint avahi_dns_packet_consume_name(AvahiDnsPacket *p, gchar *ret_name, guint l) {
 361     gint r;
 362
 363     if ((r = consume_labels(p, p->rindex, ret_name, l)) < 0)
 364         return -1;
 365
 366     p->rindex += r;
 367     return 0;
 368 }
 369
 370 gint avahi_dns_packet_consume_uint16(AvahiDnsPacket *p, guint16 *ret_v) {
 371     g_assert(p);
 372     g_assert(ret_v);
 373
 374     if (p->rindex + sizeof(guint16) > p->size)
 375         return -1;
 376
 377     *ret_v = g_ntohs(*((guint16*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex)));
 378     p->rindex += sizeof(guint16);
 379
 380     return 0;
 381 }
 382
 383 gint avahi_dns_packet_consume_uint32(AvahiDnsPacket *p, guint32 *ret_v) {
 384     g_assert(p);
 385     g_assert(ret_v);
 386
 387     if (p->rindex + sizeof(guint32) > p->size)
 388         return -1;
 389
 390     *ret_v = g_ntohl(*((guint32*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex)));
 391     p->rindex += sizeof(guint32);
 392
 393     return 0;
 394 }
 395
 396 gint avahi_dns_packet_consume_bytes(AvahiDnsPacket *p, gpointer ret_data, guint l) {
 397     g_assert(p);
 398     g_assert(ret_data);
 399     g_assert(l > 0);
 400
 401     if (p->rindex + l > p->size)
 402         return -1;
 403
 404     memcpy(ret_data, AVAHI_DNS_PACKET_DATA(p) + p->rindex, l);
 405     p->rindex += l;
 406
 407     return 0;
 408 }
 409
 410 gint avahi_dns_packet_consume_string(AvahiDnsPacket *p, gchar *ret_string, guint l) {
 411     guint k;
 412
 413     g_assert(p);
 414     g_assert(ret_string);
 415     g_assert(l > 0);
 416
 417     if (p->rindex >= p->size)
 418         return -1;
 419
 420     k = AVAHI_DNS_PACKET_DATA(p)[p->rindex];
 421
 422     if (p->rindex+1+k > p->size)
 423         return -1;
 424
 425     if (l > k+1)
 426         l = k+1;
 427
 428     memcpy(ret_string, AVAHI_DNS_PACKET_DATA(p)+p->rindex+1, l-1);
 429     ret_string[l-1] = 0;
 430
 431
 432     p->rindex += 1+k;
 433
 434     return 0;
 435
 436 }
 437
 438 gconstpointer avahi_dns_packet_get_rptr(AvahiDnsPacket *p) {
 439     g_assert(p);
 440
 441     if (p->rindex > p->size)
 442         return NULL;
 443
 444     return AVAHI_DNS_PACKET_DATA(p) + p->rindex;
 445 }
 446
 447 gint avahi_dns_packet_skip(AvahiDnsPacket *p, guint length) {
 448     g_assert(p);
 449
 450     if (p->rindex + length > p->size)
 451         return -1;
 452
 453     p->rindex += length;
 454     return 0;
 455 }
 456
 457 AvahiRecord* avahi_dns_packet_consume_record(AvahiDnsPacket *p, gboolean *ret_cache_flush) {
 458     gchar name[257], buf[257];
 459     guint16 type, class;
 460     guint32 ttl;
 461     guint16 rdlength;
 462     AvahiRecord *r = NULL;
 463     gconstpointer start;
 464
 465     g_assert(p);
 466     g_assert(ret_cache_flush);
 467
 468 /*     g_message("consume_record()"); */
 469
 470     if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
 471         avahi_dns_packet_consume_uint16(p, &type) < 0 ||
 472         avahi_dns_packet_consume_uint16(p, &class) < 0 ||
 473         avahi_dns_packet_consume_uint32(p, &ttl) < 0 ||
 474         avahi_dns_packet_consume_uint16(p, &rdlength) < 0 ||
 475         p->rindex + rdlength > p->size)
 476         goto fail;
 477
 478 /*     g_message("name = %s, rdlength = %u", name, rdlength); */
 479
 480     *ret_cache_flush = !!(class & AVAHI_DNS_CACHE_FLUSH);
 481     class &= ~AVAHI_DNS_CACHE_FLUSH;
 482
 483     start = avahi_dns_packet_get_rptr(p);
 484
 485     r = avahi_record_new_full(name, class, type);
 486
 487     switch (type) {
 488         case AVAHI_DNS_TYPE_PTR:
 489         case AVAHI_DNS_TYPE_CNAME:
 490
 491 /*             g_message("ptr"); */
 492
 493             if (avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
 494                 goto fail;
 495
 496             r->data.ptr.name = g_strdup(buf);
 497             break;
 498
 499
 500         case AVAHI_DNS_TYPE_SRV:
 501
 502 /*             g_message("srv"); */
 503
 504             if (avahi_dns_packet_consume_uint16(p, &r->data.srv.priority) < 0 ||
 505                 avahi_dns_packet_consume_uint16(p, &r->data.srv.weight) < 0 ||
 506                 avahi_dns_packet_consume_uint16(p, &r->data.srv.port) < 0 ||
 507                 avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
 508                 goto fail;
 509
 510             r->data.srv.name = g_strdup(buf);
 511             break;
 512
 513         case AVAHI_DNS_TYPE_HINFO:
 514
 515 /*             g_message("hinfo"); */
 516
 517             if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
 518                 goto fail;
 519
 520             r->data.hinfo.cpu = g_strdup(buf);
 521
 522             if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
 523                 goto fail;
 524
 525             r->data.hinfo.os = g_strdup(buf);
 526             break;
 527
 528         case AVAHI_DNS_TYPE_TXT:
 529
 530 /*             g_message("txt"); */
 531
 532             if (rdlength > 0) {
 533                 r->data.txt.string_list = avahi_string_list_parse(avahi_dns_packet_get_rptr(p), rdlength);
 534
 535                 if (avahi_dns_packet_skip(p, rdlength) < 0)
 536                     goto fail;
 537             } else
 538                 r->data.txt.string_list = NULL;
 539
 540             break;
 541
 542         case AVAHI_DNS_TYPE_A:
 543
 544 /*             g_message("A"); */
 545
 546             if (avahi_dns_packet_consume_bytes(p, &r->data.a.address, sizeof(AvahiIPv4Address)) < 0)
 547                 goto fail;
 548
 549             break;
 550
 551         case AVAHI_DNS_TYPE_AAAA:
 552
 553 /*             g_message("aaaa"); */
 554
 555             if (avahi_dns_packet_consume_bytes(p, &r->data.aaaa.address, sizeof(AvahiIPv6Address)) < 0)
 556                 goto fail;
 557
 558             break;
 559
 560         default:
 561
 562 /*             g_message("generic"); */
 563
 564             if (rdlength > 0) {
 565
 566                 r->data.generic.data = g_memdup(avahi_dns_packet_get_rptr(p), rdlength);
 567
 568                 if (avahi_dns_packet_skip(p, rdlength) < 0)
 569                     goto fail;
 570             }
 571
 572             break;
 573     }
 574
 575 /*     g_message("%i == %u ?", (guint8*) avahi_dns_packet_get_rptr(p) - (guint8*) start, rdlength); */
 576
 577     /* Check if we read enough data */
 578     if ((guint8*) avahi_dns_packet_get_rptr(p) - (guint8*) start != rdlength)
 579         goto fail;
 580
 581     r->ttl = ttl;
 582
 583     return r;
 584
 585 fail:
 586     if (r)
 587         avahi_record_unref(r);
 588
 589     return NULL;
 590 }
 591
 592 AvahiKey* avahi_dns_packet_consume_key(AvahiDnsPacket *p, gboolean *ret_unicast_response) {
 593     gchar name[256];
 594     guint16 type, class;
 595
 596     g_assert(p);
 597     g_assert(ret_unicast_response);
 598
 599     if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
 600         avahi_dns_packet_consume_uint16(p, &type) < 0 ||
 601         avahi_dns_packet_consume_uint16(p, &class) < 0)
 602         return NULL;
 603
 604     *ret_unicast_response = !!(class & AVAHI_DNS_UNICAST_RESPONSE);
 605     class &= ~AVAHI_DNS_UNICAST_RESPONSE;
 606
 607     return avahi_key_new(name, class, type);
 608 }
 609
 610 guint8* avahi_dns_packet_append_key(AvahiDnsPacket *p, AvahiKey *k, gboolean unicast_response) {
 611     guint8 *t;
 612     guint size;
 613
 614     g_assert(p);
 615     g_assert(k);
 616
 617     size = p->size;
 618
 619     if (!(t = avahi_dns_packet_append_name(p, k->name)) ||
 620         !avahi_dns_packet_append_uint16(p, k->type) ||
 621         !avahi_dns_packet_append_uint16(p, k->class | (unicast_response ? AVAHI_DNS_UNICAST_RESPONSE : 0))) {
 622         p->size = size;
 623         return NULL;
 624     }
 625
 626     return t;
 627 }
 628
 629 guint8* avahi_dns_packet_append_record(AvahiDnsPacket *p, AvahiRecord *r, gboolean cache_flush, guint max_ttl) {
 630     guint8 *t, *l, *start;
 631     guint size;
 632
 633     g_assert(p);
 634     g_assert(r);
 635
 636     size = p->size;
 637
 638     if (!(t = avahi_dns_packet_append_name(p, r->key->name)) ||
 639         !avahi_dns_packet_append_uint16(p, r->key->type) ||
 640         !avahi_dns_packet_append_uint16(p, cache_flush ? (r->key->class | AVAHI_DNS_CACHE_FLUSH) : (r->key->class &~ AVAHI_DNS_CACHE_FLUSH)) ||
 641         !avahi_dns_packet_append_uint32(p, (max_ttl && r->ttl > max_ttl) ? max_ttl : r->ttl) ||
 642         !(l = avahi_dns_packet_append_uint16(p, 0)))
 643         goto fail;
 644
 645     start = avahi_dns_packet_extend(p, 0);
 646
 647     switch (r->key->type) {
 648
 649         case AVAHI_DNS_TYPE_PTR:
 650         case AVAHI_DNS_TYPE_CNAME :
 651
 652             if (!(avahi_dns_packet_append_name(p, r->data.ptr.name)))
 653                 goto fail;
 654
 655             break;
 656
 657         case AVAHI_DNS_TYPE_SRV:
 658
 659             if (!avahi_dns_packet_append_uint16(p, r->data.srv.priority) ||
 660                 !avahi_dns_packet_append_uint16(p, r->data.srv.weight) ||
 661                 !avahi_dns_packet_append_uint16(p, r->data.srv.port) ||
 662                 !avahi_dns_packet_append_name(p, r->data.srv.name))
 663                 goto fail;
 664
 665             break;
 666
 667         case AVAHI_DNS_TYPE_HINFO:
 668             if (!avahi_dns_packet_append_string(p, r->data.hinfo.cpu) ||
 669                 !avahi_dns_packet_append_string(p, r->data.hinfo.os))
 670                 goto fail;
 671
 672             break;
 673
 674         case AVAHI_DNS_TYPE_TXT: {
 675
 676             guint8 *data;
 677             guint size;
 678
 679             size = avahi_string_list_serialize(r->data.txt.string_list, NULL, 0);
 680
 681 /*             g_message("appending string: %u %p", size, r->data.txt.string_list); */
 682
 683             if (!(data = avahi_dns_packet_extend(p, size)))
 684                 goto fail;
 685
 686             avahi_string_list_serialize(r->data.txt.string_list, data, size);
 687             break;
 688         }
 689
 690
 691         case AVAHI_DNS_TYPE_A:
 692
 693             if (!avahi_dns_packet_append_bytes(p, &r->data.a.address, sizeof(r->data.a.address)))
 694                 goto fail;
 695
 696             break;
 697
 698         case AVAHI_DNS_TYPE_AAAA:
 699
 700             if (!avahi_dns_packet_append_bytes(p, &r->data.aaaa.address, sizeof(r->data.aaaa.address)))
 701                 goto fail;
 702
 703             break;
 704
 705         default:
 706
 707             if (r->data.generic.size &&
 708                 avahi_dns_packet_append_bytes(p, r->data.generic.data, r->data.generic.size))
 709                 goto fail;
 710
 711             break;
 712     }
 713
 714
 715
 716
 717     size = avahi_dns_packet_extend(p, 0) - start;
 718     g_assert(size <= 0xFFFF);
 719
 720 /*     g_message("appended %u", size); */
 721
 722     * (guint16*) l = g_htons((guint16) size);
 723
 724     return t;
 725
 726
 727 fail:
 728     p->size = size;
 729     return NULL;
 730 }
 731
 732 gboolean avahi_dns_packet_is_empty(AvahiDnsPacket *p) {
 733     g_assert(p);
 734
 735     return p->size <= AVAHI_DNS_PACKET_HEADER_SIZE;
 736 }
 737
 738 guint avahi_dns_packet_space(AvahiDnsPacket *p) {
 739     g_assert(p);
 740
 741     g_assert(p->size <= p->max_size);
 742
 743     return p->max_size - p->size;
 744 }