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
 141
 142 /* Read the first label from string *name, unescape "\" and write it to dest */
 143 gchar *avahi_unescape_label(gchar *dest, guint size, const gchar **name) {
 144     guint i = 0;
 145     gchar *d;
 146
 147     g_assert(dest);
 148     g_assert(size > 0);
 149     g_assert(name);
 150     g_assert(*name);
 151
 152     d = dest;
 153
 154     for (;;) {
 155         if (i >= size)
 156             return NULL;
 157
 158         if (**name == '.') {
 159             (*name)++;
 160             break;
 161         }
 162
 163         if (**name == 0)
 164             break;
 165
 166         if (**name == '\\') {
 167             (*name) ++;
 168
 169             if (**name == 0)
 170                 break;
 171         }
 172
 173         *(d++) = *((*name) ++);
 174         i++;
 175     }
 176
 177     g_assert(i < size);
 178
 179     *d = 0;
 180
 181     return dest;
 182 }
 183
 184 guint8* avahi_dns_packet_append_name(AvahiDnsPacket *p, const gchar *name) {
 185     guint8 *d, *saved_ptr = NULL;
 186     guint saved_size;
 187
 188     g_assert(p);
 189     g_assert(name);
 190
 191     saved_size = p->size;
 192     saved_ptr = avahi_dns_packet_extend(p, 0);
 193
 194     while (*name) {
 195         guint8* prev;
 196         const gchar *pname;
 197         gchar label[64];
 198
 199         /* Check whether we can compress this name. */
 200
 201         if (p->name_table && (prev = g_hash_table_lookup(p->name_table, name))) {
 202             guint index;
 203
 204             g_assert(prev >= AVAHI_DNS_PACKET_DATA(p));
 205             index = (guint) (prev - AVAHI_DNS_PACKET_DATA(p));
 206
 207             g_assert(index < p->size);
 208
 209             if (index < 0x4000) {
 210                 guint16 *t;
 211                 if (!(t = (guint16*) avahi_dns_packet_extend(p, sizeof(guint16))))
 212                     return NULL;
 213
 214                 *t = g_htons((0xC000 | index));
 215                 return saved_ptr;
 216             }
 217         }
 218
 219         pname = name;
 220
 221         if (!(avahi_unescape_label(label, sizeof(label), &name)))
 222             goto fail;
 223
 224         if (!(d = avahi_dns_packet_append_string(p, label)))
 225             goto fail;
 226
 227         if (!p->name_table)
 228             p->name_table = g_hash_table_new_full((GHashFunc) avahi_domain_hash, (GEqualFunc) avahi_domain_equal, g_free, NULL);
 229
 230         g_hash_table_insert(p->name_table, g_strdup(pname), d);
 231     }
 232
 233     if (!(d = avahi_dns_packet_extend(p, 1)))
 234         goto fail;
 235
 236     *d = 0;
 237
 238     return saved_ptr;
 239
 240 fail:
 241     p->size = saved_size;
 242     return NULL;
 243 }
 244
 245 guint8* avahi_dns_packet_append_uint16(AvahiDnsPacket *p, guint16 v) {
 246     guint8 *d;
 247     g_assert(p);
 248
 249     if (!(d = avahi_dns_packet_extend(p, sizeof(guint16))))
 250         return NULL;
 251
 252     *((guint16*) d) = g_htons(v);
 253     return d;
 254 }
 255
 256 guint8 *avahi_dns_packet_append_uint32(AvahiDnsPacket *p, guint32 v) {
 257     guint8 *d;
 258     g_assert(p);
 259
 260     if (!(d = avahi_dns_packet_extend(p, sizeof(guint32))))
 261         return NULL;
 262
 263     *((guint32*) d) = g_htonl(v);
 264
 265     return d;
 266 }
 267
 268 guint8 *avahi_dns_packet_append_bytes(AvahiDnsPacket  *p, gconstpointer b, guint l) {
 269     guint8* d;
 270
 271     g_assert(p);
 272     g_assert(b);
 273     g_assert(l);
 274
 275     if (!(d = avahi_dns_packet_extend(p, l)))
 276         return NULL;
 277
 278     memcpy(d, b, l);
 279     return d;
 280 }
 281
 282 guint8* avahi_dns_packet_append_string(AvahiDnsPacket *p, const gchar *s) {
 283     guint8* d;
 284     guint k;
 285
 286     g_assert(p);
 287     g_assert(s);
 288
 289     if ((k = strlen(s)) >= 255)
 290         k = 255;
 291
 292     if (!(d = avahi_dns_packet_extend(p, k+1)))
 293         return NULL;
 294
 295     *d = (guint8) k;
 296     memcpy(d+1, s, k);
 297
 298     return d;
 299 }
 300
 301 guint8 *avahi_dns_packet_extend(AvahiDnsPacket *p, guint l) {
 302     guint8 *d;
 303
 304     g_assert(p);
 305
 306     if (p->size+l > p->max_size)
 307         return NULL;
 308
 309     d = AVAHI_DNS_PACKET_DATA(p) + p->size;
 310     p->size += l;
 311
 312     return d;
 313 }
 314
 315 gint avahi_dns_packet_check_valid(AvahiDnsPacket *p) {
 316     guint16 flags;
 317     g_assert(p);
 318
 319     if (p->size < 12)
 320         return -1;
 321
 322     flags = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS);
 323
 324     if (flags & AVAHI_DNS_FLAG_OPCODE || flags & AVAHI_DNS_FLAG_RCODE)
 325         return -1;
 326
 327     return 0;
 328 }
 329
 330 gint avahi_dns_packet_is_query(AvahiDnsPacket *p) {
 331     g_assert(p);
 332
 333     return !(avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) & AVAHI_DNS_FLAG_QR);
 334 }
 335
 336 /* Read a label from a DNS packet, escape "\" and ".", append \0 */
 337 static gchar *escape_label(guint8* src, guint src_length, gchar **ret_name, guint *ret_name_length) {
 338     gchar *r;
 339
 340     g_assert(src);
 341     g_assert(ret_name);
 342     g_assert(*ret_name);
 343     g_assert(ret_name_length);
 344     g_assert(*ret_name_length > 0);
 345
 346     r = *ret_name;
 347
 348     while (src_length > 0) {
 349         if (*src == '.' || *src == '\\') {
 350             if (*ret_name_length < 3)
 351                 return NULL;
 352
 353             *((*ret_name) ++) = '\\';
 354             (*ret_name_length) --;
 355         }
 356
 357         if (*ret_name_length < 2)
 358             return NULL;
 359
 360         *((*ret_name)++) = *src;
 361         (*ret_name_length) --;
 362
 363         src_length --;
 364         src++;
 365     }
 366
 367     **ret_name = 0;
 368
 369     return r;
 370 }
 371
 372 static gint consume_labels(AvahiDnsPacket *p, guint index, gchar *ret_name, guint l) {
 373     gint ret = 0;
 374     int compressed = 0;
 375     int first_label = 1;
 376     g_assert(p && ret_name && l);
 377
 378     for (;;) {
 379         guint8 n;
 380
 381         if (index+1 > p->size)
 382             return -1;
 383
 384         n = AVAHI_DNS_PACKET_DATA(p)[index];
 385
 386         if (!n) {
 387             index++;
 388             if (!compressed)
 389                 ret++;
 390
 391             if (l < 1)
 392                 return -1;
 393             *ret_name = 0;
 394
 395             return ret;
 396
 397         } else if (n <= 63) {
 398             /* Uncompressed label */
 399             index++;
 400             if (!compressed)
 401                 ret++;
 402
 403             if (index + n > p->size)
 404                 return -1;
 405
 406             if ((guint) n + 1 > l)
 407                 return -1;
 408
 409             if (!first_label) {
 410                 *(ret_name++) = '.';
 411                 l--;
 412             } else
 413                 first_label = 0;
 414
 415             if (!(escape_label(AVAHI_DNS_PACKET_DATA(p) + index, n, &ret_name, &l)))
 416                 return -1;
 417
 418             index += n;
 419
 420             if (!compressed)
 421                 ret += n;
 422         } else if ((n & 0xC0) == 0xC0) {
 423             /* Compressed label */
 424
 425             if (index+2 > p->size)
 426                 return -1;
 427
 428             index = ((guint) (AVAHI_DNS_PACKET_DATA(p)[index] & ~0xC0)) << 8 | AVAHI_DNS_PACKET_DATA(p)[index+1];
 429
 430             if (!compressed)
 431                 ret += 2;
 432
 433             compressed = 1;
 434         } else
 435             return -1;
 436     }
 437 }
 438
 439 gint avahi_dns_packet_consume_name(AvahiDnsPacket *p, gchar *ret_name, guint l) {
 440     gint r;
 441
 442     if ((r = consume_labels(p, p->rindex, ret_name, l)) < 0)
 443         return -1;
 444
 445     p->rindex += r;
 446     return 0;
 447 }
 448
 449 gint avahi_dns_packet_consume_uint16(AvahiDnsPacket *p, guint16 *ret_v) {
 450     g_assert(p);
 451     g_assert(ret_v);
 452
 453     if (p->rindex + sizeof(guint16) > p->size)
 454         return -1;
 455
 456     *ret_v = g_ntohs(*((guint16*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex)));
 457     p->rindex += sizeof(guint16);
 458
 459     return 0;
 460 }
 461
 462 gint avahi_dns_packet_consume_uint32(AvahiDnsPacket *p, guint32 *ret_v) {
 463     g_assert(p);
 464     g_assert(ret_v);
 465
 466     if (p->rindex + sizeof(guint32) > p->size)
 467         return -1;
 468
 469     *ret_v = g_ntohl(*((guint32*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex)));
 470     p->rindex += sizeof(guint32);
 471
 472     return 0;
 473 }
 474
 475 gint avahi_dns_packet_consume_bytes(AvahiDnsPacket *p, gpointer ret_data, guint l) {
 476     g_assert(p);
 477     g_assert(ret_data);
 478     g_assert(l > 0);
 479
 480     if (p->rindex + l > p->size)
 481         return -1;
 482
 483     memcpy(ret_data, AVAHI_DNS_PACKET_DATA(p) + p->rindex, l);
 484     p->rindex += l;
 485
 486     return 0;
 487 }
 488
 489 gint avahi_dns_packet_consume_string(AvahiDnsPacket *p, gchar *ret_string, guint l) {
 490     guint k;
 491
 492     g_assert(p);
 493     g_assert(ret_string);
 494     g_assert(l > 0);
 495
 496     if (p->rindex >= p->size)
 497         return -1;
 498
 499     k = AVAHI_DNS_PACKET_DATA(p)[p->rindex];
 500
 501     if (p->rindex+1+k > p->size)
 502         return -1;
 503
 504     if (l > k+1)
 505         l = k+1;
 506
 507     memcpy(ret_string, AVAHI_DNS_PACKET_DATA(p)+p->rindex+1, l-1);
 508     ret_string[l-1] = 0;
 509
 510
 511     p->rindex += 1+k;
 512
 513     return 0;
 514
 515 }
 516
 517 gconstpointer avahi_dns_packet_get_rptr(AvahiDnsPacket *p) {
 518     g_assert(p);
 519
 520     if (p->rindex > p->size)
 521         return NULL;
 522
 523     return AVAHI_DNS_PACKET_DATA(p) + p->rindex;
 524 }
 525
 526 gint avahi_dns_packet_skip(AvahiDnsPacket *p, guint length) {
 527     g_assert(p);
 528
 529     if (p->rindex + length > p->size)
 530         return -1;
 531
 532     p->rindex += length;
 533     return 0;
 534 }
 535
 536 AvahiRecord* avahi_dns_packet_consume_record(AvahiDnsPacket *p, gboolean *ret_cache_flush) {
 537     gchar name[257], buf[257];
 538     guint16 type, class;
 539     guint32 ttl;
 540     guint16 rdlength;
 541     AvahiRecord *r = NULL;
 542     gconstpointer start;
 543
 544     g_assert(p);
 545     g_assert(ret_cache_flush);
 546
 547 /*     g_message("consume_record()"); */
 548
 549     if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
 550         avahi_dns_packet_consume_uint16(p, &type) < 0 ||
 551         avahi_dns_packet_consume_uint16(p, &class) < 0 ||
 552         avahi_dns_packet_consume_uint32(p, &ttl) < 0 ||
 553         avahi_dns_packet_consume_uint16(p, &rdlength) < 0 ||
 554         p->rindex + rdlength > p->size)
 555         goto fail;
 556
 557 /*     g_message("name = %s, rdlength = %u", name, rdlength); */
 558
 559     *ret_cache_flush = !!(class & AVAHI_DNS_CACHE_FLUSH);
 560     class &= ~AVAHI_DNS_CACHE_FLUSH;
 561
 562     start = avahi_dns_packet_get_rptr(p);
 563
 564     r = avahi_record_new_full(name, class, type);
 565
 566     switch (type) {
 567         case AVAHI_DNS_TYPE_PTR:
 568         case AVAHI_DNS_TYPE_CNAME:
 569
 570 /*             g_message("ptr"); */
 571
 572             if (avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
 573                 goto fail;
 574
 575             r->data.ptr.name = g_strdup(buf);
 576             break;
 577
 578
 579         case AVAHI_DNS_TYPE_SRV:
 580
 581 /*             g_message("srv"); */
 582
 583             if (avahi_dns_packet_consume_uint16(p, &r->data.srv.priority) < 0 ||
 584                 avahi_dns_packet_consume_uint16(p, &r->data.srv.weight) < 0 ||
 585                 avahi_dns_packet_consume_uint16(p, &r->data.srv.port) < 0 ||
 586                 avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
 587                 goto fail;
 588
 589             r->data.srv.name = g_strdup(buf);
 590             break;
 591
 592         case AVAHI_DNS_TYPE_HINFO:
 593
 594 /*             g_message("hinfo"); */
 595
 596             if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
 597                 goto fail;
 598
 599             r->data.hinfo.cpu = g_strdup(buf);
 600
 601             if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
 602                 goto fail;
 603
 604             r->data.hinfo.os = g_strdup(buf);
 605             break;
 606
 607         case AVAHI_DNS_TYPE_TXT:
 608
 609 /*             g_message("txt"); */
 610
 611             if (rdlength > 0) {
 612                 r->data.txt.string_list = avahi_string_list_parse(avahi_dns_packet_get_rptr(p), rdlength);
 613
 614                 if (avahi_dns_packet_skip(p, rdlength) < 0)
 615                     goto fail;
 616             } else
 617                 r->data.txt.string_list = NULL;
 618
 619             break;
 620
 621         case AVAHI_DNS_TYPE_A:
 622
 623 /*             g_message("A"); */
 624
 625             if (avahi_dns_packet_consume_bytes(p, &r->data.a.address, sizeof(AvahiIPv4Address)) < 0)
 626                 goto fail;
 627
 628             break;
 629
 630         case AVAHI_DNS_TYPE_AAAA:
 631
 632 /*             g_message("aaaa"); */
 633
 634             if (avahi_dns_packet_consume_bytes(p, &r->data.aaaa.address, sizeof(AvahiIPv6Address)) < 0)
 635                 goto fail;
 636
 637             break;
 638
 639         default:
 640
 641 /*             g_message("generic"); */
 642
 643             if (rdlength > 0) {
 644
 645                 r->data.generic.data = g_memdup(avahi_dns_packet_get_rptr(p), rdlength);
 646
 647                 if (avahi_dns_packet_skip(p, rdlength) < 0)
 648                     goto fail;
 649             }
 650
 651             break;
 652     }
 653
 654 /*     g_message("%i == %u ?", (guint8*) avahi_dns_packet_get_rptr(p) - (guint8*) start, rdlength); */
 655
 656     /* Check if we read enough data */
 657     if ((guint8*) avahi_dns_packet_get_rptr(p) - (guint8*) start != rdlength)
 658         goto fail;
 659
 660     r->ttl = ttl;
 661
 662     return r;
 663
 664 fail:
 665     if (r)
 666         avahi_record_unref(r);
 667
 668     return NULL;
 669 }
 670
 671 AvahiKey* avahi_dns_packet_consume_key(AvahiDnsPacket *p, gboolean *ret_unicast_response) {
 672     gchar name[256];
 673     guint16 type, class;
 674
 675     g_assert(p);
 676     g_assert(ret_unicast_response);
 677
 678     if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
 679         avahi_dns_packet_consume_uint16(p, &type) < 0 ||
 680         avahi_dns_packet_consume_uint16(p, &class) < 0)
 681         return NULL;
 682
 683     *ret_unicast_response = !!(class & AVAHI_DNS_UNICAST_RESPONSE);
 684     class &= ~AVAHI_DNS_UNICAST_RESPONSE;
 685
 686     return avahi_key_new(name, class, type);
 687 }
 688
 689 guint8* avahi_dns_packet_append_key(AvahiDnsPacket *p, AvahiKey *k, gboolean unicast_response) {
 690     guint8 *t;
 691     guint size;
 692
 693     g_assert(p);
 694     g_assert(k);
 695
 696     size = p->size;
 697
 698     if (!(t = avahi_dns_packet_append_name(p, k->name)) ||
 699         !avahi_dns_packet_append_uint16(p, k->type) ||
 700         !avahi_dns_packet_append_uint16(p, k->class | (unicast_response ? AVAHI_DNS_UNICAST_RESPONSE : 0))) {
 701         p->size = size;
 702         return NULL;
 703     }
 704
 705     return t;
 706 }
 707
 708 guint8* avahi_dns_packet_append_record(AvahiDnsPacket *p, AvahiRecord *r, gboolean cache_flush, guint max_ttl) {
 709     guint8 *t, *l, *start;
 710     guint size;
 711
 712     g_assert(p);
 713     g_assert(r);
 714
 715     size = p->size;
 716
 717     if (!(t = avahi_dns_packet_append_name(p, r->key->name)) ||
 718         !avahi_dns_packet_append_uint16(p, r->key->type) ||
 719         !avahi_dns_packet_append_uint16(p, cache_flush ? (r->key->class | AVAHI_DNS_CACHE_FLUSH) : (r->key->class &~ AVAHI_DNS_CACHE_FLUSH)) ||
 720         !avahi_dns_packet_append_uint32(p, (max_ttl && r->ttl > max_ttl) ? max_ttl : r->ttl) ||
 721         !(l = avahi_dns_packet_append_uint16(p, 0)))
 722         goto fail;
 723
 724     start = avahi_dns_packet_extend(p, 0);
 725
 726     switch (r->key->type) {
 727
 728         case AVAHI_DNS_TYPE_PTR:
 729         case AVAHI_DNS_TYPE_CNAME :
 730
 731             if (!(avahi_dns_packet_append_name(p, r->data.ptr.name)))
 732                 goto fail;
 733
 734             break;
 735
 736         case AVAHI_DNS_TYPE_SRV:
 737
 738             if (!avahi_dns_packet_append_uint16(p, r->data.srv.priority) ||
 739                 !avahi_dns_packet_append_uint16(p, r->data.srv.weight) ||
 740                 !avahi_dns_packet_append_uint16(p, r->data.srv.port) ||
 741                 !avahi_dns_packet_append_name(p, r->data.srv.name))
 742                 goto fail;
 743
 744             break;
 745
 746         case AVAHI_DNS_TYPE_HINFO:
 747             if (!avahi_dns_packet_append_string(p, r->data.hinfo.cpu) ||
 748                 !avahi_dns_packet_append_string(p, r->data.hinfo.os))
 749                 goto fail;
 750
 751             break;
 752
 753         case AVAHI_DNS_TYPE_TXT: {
 754
 755             guint8 *data;
 756             guint size;
 757
 758             size = avahi_string_list_serialize(r->data.txt.string_list, NULL, 0);
 759
 760 /*             g_message("appending string: %u %p", size, r->data.txt.string_list); */
 761
 762             if (!(data = avahi_dns_packet_extend(p, size)))
 763                 goto fail;
 764
 765             avahi_string_list_serialize(r->data.txt.string_list, data, size);
 766             break;
 767         }
 768
 769
 770         case AVAHI_DNS_TYPE_A:
 771
 772             if (!avahi_dns_packet_append_bytes(p, &r->data.a.address, sizeof(r->data.a.address)))
 773                 goto fail;
 774
 775             break;
 776
 777         case AVAHI_DNS_TYPE_AAAA:
 778
 779             if (!avahi_dns_packet_append_bytes(p, &r->data.aaaa.address, sizeof(r->data.aaaa.address)))
 780                 goto fail;
 781
 782             break;
 783
 784         default:
 785
 786             if (r->data.generic.size &&
 787                 avahi_dns_packet_append_bytes(p, r->data.generic.data, r->data.generic.size))
 788                 goto fail;
 789
 790             break;
 791     }
 792
 793
 794
 795
 796     size = avahi_dns_packet_extend(p, 0) - start;
 797     g_assert(size <= 0xFFFF);
 798
 799 /*     g_message("appended %u", size); */
 800
 801     * (guint16*) l = g_htons((guint16) size);
 802
 803     return t;
 804
 805
 806 fail:
 807     p->size = size;
 808     return NULL;
 809 }
 810
 811 gboolean avahi_dns_packet_is_empty(AvahiDnsPacket *p) {
 812     g_assert(p);
 813
 814     return p->size <= AVAHI_DNS_PACKET_HEADER_SIZE;
 815 }
 816
 817 guint avahi_dns_packet_space(AvahiDnsPacket *p) {
 818     g_assert(p);
 819
 820     g_assert(p->size <= p->max_size);
 821
 822     return p->max_size - p->size;
 823 }