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 /* Read the first label from string *name, unescape "\" and write it to dest */
 135 gchar *avahi_unescape_label(gchar *dest, guint size, const gchar **name) {
 136     guint i = 0;
 137     gchar *d;
 138
 139     g_assert(dest);
 140     g_assert(size > 0);
 141     g_assert(name);
 142     g_assert(*name);
 143
 144     d = dest;
 145
 146     for (;;) {
 147         if (i >= size)
 148             return NULL;
 149
 150         if (**name == '.') {
 151             (*name)++;
 152             break;
 153         }
 154
 155         if (**name == 0)
 156             break;
 157
 158         if (**name == '\\') {
 159             (*name) ++;
 160
 161             if (**name == 0)
 162                 break;
 163         }
 164
 165         *(d++) = *((*name) ++);
 166         i++;
 167     }
 168
 169     g_assert(i < size);
 170
 171     *d = 0;
 172
 173     return dest;
 174 }
 175
 176 guint8* avahi_dns_packet_append_name(AvahiDnsPacket *p, const gchar *name) {
 177     guint8 *d, *saved_ptr = NULL;
 178     guint saved_size;
 179
 180     g_assert(p);
 181     g_assert(name);
 182
 183     saved_size = p->size;
 184     saved_ptr = avahi_dns_packet_extend(p, 0);
 185
 186     while (*name) {
 187         guint8* prev;
 188         const gchar *pname;
 189         gchar label[64];
 190
 191         /* Check whether we can compress this name. */
 192
 193         if (p->name_table && (prev = g_hash_table_lookup(p->name_table, name))) {
 194             guint index;
 195
 196             g_assert(prev >= AVAHI_DNS_PACKET_DATA(p));
 197             index = (guint) (prev - AVAHI_DNS_PACKET_DATA(p));
 198
 199             g_assert(index < p->size);
 200
 201             if (index < 0x4000) {
 202                 guint16 *t;
 203                 if (!(t = (guint16*) avahi_dns_packet_extend(p, sizeof(guint16))))
 204                     return NULL;
 205
 206                 *t = g_htons((0xC000 | index));
 207                 return saved_ptr;
 208             }
 209         }
 210
 211         pname = name;
 212
 213         if (!(avahi_unescape_label(label, sizeof(label), &name)))
 214             goto fail;
 215
 216         if (!(d = avahi_dns_packet_append_string(p, label)))
 217             goto fail;
 218
 219         if (!p->name_table)
 220             p->name_table = g_hash_table_new_full((GHashFunc) avahi_domain_hash, (GEqualFunc) avahi_domain_equal, g_free, NULL);
 221
 222         g_hash_table_insert(p->name_table, g_strdup(pname), d);
 223     }
 224
 225     if (!(d = avahi_dns_packet_extend(p, 1)))
 226         goto fail;
 227
 228     *d = 0;
 229
 230     return saved_ptr;
 231
 232 fail:
 233     p->size = saved_size;
 234     return NULL;
 235 }
 236
 237 guint8* avahi_dns_packet_append_uint16(AvahiDnsPacket *p, guint16 v) {
 238     guint8 *d;
 239     g_assert(p);
 240
 241     if (!(d = avahi_dns_packet_extend(p, sizeof(guint16))))
 242         return NULL;
 243
 244     *((guint16*) d) = g_htons(v);
 245     return d;
 246 }
 247
 248 guint8 *avahi_dns_packet_append_uint32(AvahiDnsPacket *p, guint32 v) {
 249     guint8 *d;
 250     g_assert(p);
 251
 252     if (!(d = avahi_dns_packet_extend(p, sizeof(guint32))))
 253         return NULL;
 254
 255     *((guint32*) d) = g_htonl(v);
 256
 257     return d;
 258 }
 259
 260 guint8 *avahi_dns_packet_append_bytes(AvahiDnsPacket  *p, gconstpointer b, guint l) {
 261     guint8* d;
 262
 263     g_assert(p);
 264     g_assert(b);
 265     g_assert(l);
 266
 267     if (!(d = avahi_dns_packet_extend(p, l)))
 268         return NULL;
 269
 270     memcpy(d, b, l);
 271     return d;
 272 }
 273
 274 guint8* avahi_dns_packet_append_string(AvahiDnsPacket *p, const gchar *s) {
 275     guint8* d;
 276     guint k;
 277
 278     g_assert(p);
 279     g_assert(s);
 280
 281     if ((k = strlen(s)) >= 255)
 282         k = 255;
 283
 284     if (!(d = avahi_dns_packet_extend(p, k+1)))
 285         return NULL;
 286
 287     *d = (guint8) k;
 288     memcpy(d+1, s, k);
 289
 290     return d;
 291 }
 292
 293 guint8 *avahi_dns_packet_extend(AvahiDnsPacket *p, guint l) {
 294     guint8 *d;
 295
 296     g_assert(p);
 297
 298     if (p->size+l > p->max_size)
 299         return NULL;
 300
 301     d = AVAHI_DNS_PACKET_DATA(p) + p->size;
 302     p->size += l;
 303
 304     return d;
 305 }
 306
 307 gint avahi_dns_packet_check_valid(AvahiDnsPacket *p) {
 308     guint16 flags;
 309     g_assert(p);
 310
 311     if (p->size < 12)
 312         return -1;
 313
 314     flags = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS);
 315
 316     if (flags & AVAHI_DNS_FLAG_OPCODE || flags & AVAHI_DNS_FLAG_RCODE)
 317         return -1;
 318
 319     return 0;
 320 }
 321
 322 gint avahi_dns_packet_is_query(AvahiDnsPacket *p) {
 323     g_assert(p);
 324
 325     return !(avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) & AVAHI_DNS_FLAG_QR);
 326 }
 327
 328 /* Read a label from a DNS packet, escape "\" and ".", append \0 */
 329 static gchar *escape_label(guint8* src, guint src_length, gchar **ret_name, guint *ret_name_length) {
 330     gchar *r;
 331
 332     g_assert(src);
 333     g_assert(ret_name);
 334     g_assert(*ret_name);
 335     g_assert(ret_name_length);
 336     g_assert(*ret_name_length > 0);
 337
 338     r = *ret_name;
 339
 340     while (src_length > 0) {
 341         if (*src == '.' || *src == '\\') {
 342             if (*ret_name_length < 3)
 343                 return NULL;
 344
 345             *((*ret_name) ++) = '\\';
 346             (*ret_name_length) --;
 347         }
 348
 349         if (*ret_name_length < 2)
 350             return NULL;
 351
 352         *((*ret_name)++) = *src;
 353         (*ret_name_length) --;
 354
 355         src_length --;
 356         src++;
 357     }
 358
 359     **ret_name = 0;
 360
 361     return r;
 362 }
 363
 364 static gint consume_labels(AvahiDnsPacket *p, guint index, gchar *ret_name, guint l) {
 365     gint ret = 0;
 366     int compressed = 0;
 367     int first_label = 1;
 368     g_assert(p && ret_name && l);
 369
 370     for (;;) {
 371         guint8 n;
 372
 373         if (index+1 > p->size)
 374             return -1;
 375
 376         n = AVAHI_DNS_PACKET_DATA(p)[index];
 377
 378         if (!n) {
 379             index++;
 380             if (!compressed)
 381                 ret++;
 382
 383             if (l < 1)
 384                 return -1;
 385             *ret_name = 0;
 386
 387             return ret;
 388
 389         } else if (n <= 63) {
 390             /* Uncompressed label */
 391             index++;
 392             if (!compressed)
 393                 ret++;
 394
 395             if (index + n > p->size)
 396                 return -1;
 397
 398             if ((guint) n + 1 > l)
 399                 return -1;
 400
 401             if (!first_label) {
 402                 *(ret_name++) = '.';
 403                 l--;
 404             } else
 405                 first_label = 0;
 406
 407             if (!(escape_label(AVAHI_DNS_PACKET_DATA(p) + index, n, &ret_name, &l)))
 408                 return -1;
 409
 410             index += n;
 411
 412             if (!compressed)
 413                 ret += n;
 414         } else if ((n & 0xC0) == 0xC0) {
 415             /* Compressed label */
 416
 417             if (index+2 > p->size)
 418                 return -1;
 419
 420             index = ((guint) (AVAHI_DNS_PACKET_DATA(p)[index] & ~0xC0)) << 8 | AVAHI_DNS_PACKET_DATA(p)[index+1];
 421
 422             if (!compressed)
 423                 ret += 2;
 424
 425             compressed = 1;
 426         } else
 427             return -1;
 428     }
 429 }
 430
 431 gint avahi_dns_packet_consume_name(AvahiDnsPacket *p, gchar *ret_name, guint l) {
 432     gint r;
 433
 434     if ((r = consume_labels(p, p->rindex, ret_name, l)) < 0)
 435         return -1;
 436
 437     p->rindex += r;
 438     return 0;
 439 }
 440
 441 gint avahi_dns_packet_consume_uint16(AvahiDnsPacket *p, guint16 *ret_v) {
 442     g_assert(p);
 443     g_assert(ret_v);
 444
 445     if (p->rindex + sizeof(guint16) > p->size)
 446         return -1;
 447
 448     *ret_v = g_ntohs(*((guint16*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex)));
 449     p->rindex += sizeof(guint16);
 450
 451     return 0;
 452 }
 453
 454 gint avahi_dns_packet_consume_uint32(AvahiDnsPacket *p, guint32 *ret_v) {
 455     g_assert(p);
 456     g_assert(ret_v);
 457
 458     if (p->rindex + sizeof(guint32) > p->size)
 459         return -1;
 460
 461     *ret_v = g_ntohl(*((guint32*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex)));
 462     p->rindex += sizeof(guint32);
 463
 464     return 0;
 465 }
 466
 467 gint avahi_dns_packet_consume_bytes(AvahiDnsPacket *p, gpointer ret_data, guint l) {
 468     g_assert(p);
 469     g_assert(ret_data);
 470     g_assert(l > 0);
 471
 472     if (p->rindex + l > p->size)
 473         return -1;
 474
 475     memcpy(ret_data, AVAHI_DNS_PACKET_DATA(p) + p->rindex, l);
 476     p->rindex += l;
 477
 478     return 0;
 479 }
 480
 481 gint avahi_dns_packet_consume_string(AvahiDnsPacket *p, gchar *ret_string, guint l) {
 482     guint k;
 483
 484     g_assert(p);
 485     g_assert(ret_string);
 486     g_assert(l > 0);
 487
 488     if (p->rindex >= p->size)
 489         return -1;
 490
 491     k = AVAHI_DNS_PACKET_DATA(p)[p->rindex];
 492
 493     if (p->rindex+1+k > p->size)
 494         return -1;
 495
 496     if (l > k+1)
 497         l = k+1;
 498
 499     memcpy(ret_string, AVAHI_DNS_PACKET_DATA(p)+p->rindex+1, l-1);
 500     ret_string[l-1] = 0;
 501
 502
 503     p->rindex += 1+k;
 504
 505     return 0;
 506
 507 }
 508
 509 gconstpointer avahi_dns_packet_get_rptr(AvahiDnsPacket *p) {
 510     g_assert(p);
 511
 512     if (p->rindex > p->size)
 513         return NULL;
 514
 515     return AVAHI_DNS_PACKET_DATA(p) + p->rindex;
 516 }
 517
 518 gint avahi_dns_packet_skip(AvahiDnsPacket *p, guint length) {
 519     g_assert(p);
 520
 521     if (p->rindex + length > p->size)
 522         return -1;
 523
 524     p->rindex += length;
 525     return 0;
 526 }
 527
 528 AvahiRecord* avahi_dns_packet_consume_record(AvahiDnsPacket *p, gboolean *ret_cache_flush) {
 529     gchar name[257], buf[257];
 530     guint16 type, class;
 531     guint32 ttl;
 532     guint16 rdlength;
 533     AvahiRecord *r = NULL;
 534     gconstpointer start;
 535
 536     g_assert(p);
 537     g_assert(ret_cache_flush);
 538
 539 /*     g_message("consume_record()"); */
 540
 541     if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
 542         avahi_dns_packet_consume_uint16(p, &type) < 0 ||
 543         avahi_dns_packet_consume_uint16(p, &class) < 0 ||
 544         avahi_dns_packet_consume_uint32(p, &ttl) < 0 ||
 545         avahi_dns_packet_consume_uint16(p, &rdlength) < 0 ||
 546         p->rindex + rdlength > p->size)
 547         goto fail;
 548
 549 /*     g_message("name = %s, rdlength = %u", name, rdlength); */
 550
 551     *ret_cache_flush = !!(class & AVAHI_DNS_CACHE_FLUSH);
 552     class &= ~AVAHI_DNS_CACHE_FLUSH;
 553
 554     start = avahi_dns_packet_get_rptr(p);
 555
 556     r = avahi_record_new_full(name, class, type);
 557
 558     switch (type) {
 559         case AVAHI_DNS_TYPE_PTR:
 560         case AVAHI_DNS_TYPE_CNAME:
 561
 562 /*             g_message("ptr"); */
 563
 564             if (avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
 565                 goto fail;
 566
 567             r->data.ptr.name = g_strdup(buf);
 568             break;
 569
 570
 571         case AVAHI_DNS_TYPE_SRV:
 572
 573 /*             g_message("srv"); */
 574
 575             if (avahi_dns_packet_consume_uint16(p, &r->data.srv.priority) < 0 ||
 576                 avahi_dns_packet_consume_uint16(p, &r->data.srv.weight) < 0 ||
 577                 avahi_dns_packet_consume_uint16(p, &r->data.srv.port) < 0 ||
 578                 avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
 579                 goto fail;
 580
 581             r->data.srv.name = g_strdup(buf);
 582             break;
 583
 584         case AVAHI_DNS_TYPE_HINFO:
 585
 586 /*             g_message("hinfo"); */
 587
 588             if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
 589                 goto fail;
 590
 591             r->data.hinfo.cpu = g_strdup(buf);
 592
 593             if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
 594                 goto fail;
 595
 596             r->data.hinfo.os = g_strdup(buf);
 597             break;
 598
 599         case AVAHI_DNS_TYPE_TXT:
 600
 601 /*             g_message("txt"); */
 602
 603             if (rdlength > 0) {
 604                 r->data.txt.string_list = avahi_string_list_parse(avahi_dns_packet_get_rptr(p), rdlength);
 605
 606                 if (avahi_dns_packet_skip(p, rdlength) < 0)
 607                     goto fail;
 608             } else
 609                 r->data.txt.string_list = NULL;
 610
 611             break;
 612
 613         case AVAHI_DNS_TYPE_A:
 614
 615 /*             g_message("A"); */
 616
 617             if (avahi_dns_packet_consume_bytes(p, &r->data.a.address, sizeof(AvahiIPv4Address)) < 0)
 618                 goto fail;
 619
 620             break;
 621
 622         case AVAHI_DNS_TYPE_AAAA:
 623
 624 /*             g_message("aaaa"); */
 625
 626             if (avahi_dns_packet_consume_bytes(p, &r->data.aaaa.address, sizeof(AvahiIPv6Address)) < 0)
 627                 goto fail;
 628
 629             break;
 630
 631         default:
 632
 633 /*             g_message("generic"); */
 634
 635             if (rdlength > 0) {
 636
 637                 r->data.generic.data = g_memdup(avahi_dns_packet_get_rptr(p), rdlength);
 638
 639                 if (avahi_dns_packet_skip(p, rdlength) < 0)
 640                     goto fail;
 641             }
 642
 643             break;
 644     }
 645
 646 /*     g_message("%i == %u ?", (guint8*) avahi_dns_packet_get_rptr(p) - (guint8*) start, rdlength); */
 647
 648     /* Check if we read enough data */
 649     if ((guint8*) avahi_dns_packet_get_rptr(p) - (guint8*) start != rdlength)
 650         goto fail;
 651
 652     r->ttl = ttl;
 653
 654     return r;
 655
 656 fail:
 657     if (r)
 658         avahi_record_unref(r);
 659
 660     return NULL;
 661 }
 662
 663 AvahiKey* avahi_dns_packet_consume_key(AvahiDnsPacket *p, gboolean *ret_unicast_response) {
 664     gchar name[256];
 665     guint16 type, class;
 666
 667     g_assert(p);
 668     g_assert(ret_unicast_response);
 669
 670     if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
 671         avahi_dns_packet_consume_uint16(p, &type) < 0 ||
 672         avahi_dns_packet_consume_uint16(p, &class) < 0)
 673         return NULL;
 674
 675     *ret_unicast_response = !!(class & AVAHI_DNS_UNICAST_RESPONSE);
 676     class &= ~AVAHI_DNS_UNICAST_RESPONSE;
 677
 678     return avahi_key_new(name, class, type);
 679 }
 680
 681 guint8* avahi_dns_packet_append_key(AvahiDnsPacket *p, AvahiKey *k, gboolean unicast_response) {
 682     guint8 *t;
 683     guint size;
 684
 685     g_assert(p);
 686     g_assert(k);
 687
 688     size = p->size;
 689
 690     if (!(t = avahi_dns_packet_append_name(p, k->name)) ||
 691         !avahi_dns_packet_append_uint16(p, k->type) ||
 692         !avahi_dns_packet_append_uint16(p, k->class | (unicast_response ? AVAHI_DNS_UNICAST_RESPONSE : 0))) {
 693         p->size = size;
 694         return NULL;
 695     }
 696
 697     return t;
 698 }
 699
 700 guint8* avahi_dns_packet_append_record(AvahiDnsPacket *p, AvahiRecord *r, gboolean cache_flush, guint max_ttl) {
 701     guint8 *t, *l, *start;
 702     guint size;
 703
 704     g_assert(p);
 705     g_assert(r);
 706
 707     size = p->size;
 708
 709     if (!(t = avahi_dns_packet_append_name(p, r->key->name)) ||
 710         !avahi_dns_packet_append_uint16(p, r->key->type) ||
 711         !avahi_dns_packet_append_uint16(p, cache_flush ? (r->key->class | AVAHI_DNS_CACHE_FLUSH) : (r->key->class &~ AVAHI_DNS_CACHE_FLUSH)) ||
 712         !avahi_dns_packet_append_uint32(p, (max_ttl && r->ttl > max_ttl) ? max_ttl : r->ttl) ||
 713         !(l = avahi_dns_packet_append_uint16(p, 0)))
 714         goto fail;
 715
 716     start = avahi_dns_packet_extend(p, 0);
 717
 718     switch (r->key->type) {
 719
 720         case AVAHI_DNS_TYPE_PTR:
 721         case AVAHI_DNS_TYPE_CNAME :
 722
 723             if (!(avahi_dns_packet_append_name(p, r->data.ptr.name)))
 724                 goto fail;
 725
 726             break;
 727
 728         case AVAHI_DNS_TYPE_SRV:
 729
 730             if (!avahi_dns_packet_append_uint16(p, r->data.srv.priority) ||
 731                 !avahi_dns_packet_append_uint16(p, r->data.srv.weight) ||
 732                 !avahi_dns_packet_append_uint16(p, r->data.srv.port) ||
 733                 !avahi_dns_packet_append_name(p, r->data.srv.name))
 734                 goto fail;
 735
 736             break;
 737
 738         case AVAHI_DNS_TYPE_HINFO:
 739             if (!avahi_dns_packet_append_string(p, r->data.hinfo.cpu) ||
 740                 !avahi_dns_packet_append_string(p, r->data.hinfo.os))
 741                 goto fail;
 742
 743             break;
 744
 745         case AVAHI_DNS_TYPE_TXT: {
 746
 747             guint8 *data;
 748             guint size;
 749
 750             size = avahi_string_list_serialize(r->data.txt.string_list, NULL, 0);
 751
 752 /*             g_message("appending string: %u %p", size, r->data.txt.string_list); */
 753
 754             if (!(data = avahi_dns_packet_extend(p, size)))
 755                 goto fail;
 756
 757             avahi_string_list_serialize(r->data.txt.string_list, data, size);
 758             break;
 759         }
 760
 761
 762         case AVAHI_DNS_TYPE_A:
 763
 764             if (!avahi_dns_packet_append_bytes(p, &r->data.a.address, sizeof(r->data.a.address)))
 765                 goto fail;
 766
 767             break;
 768
 769         case AVAHI_DNS_TYPE_AAAA:
 770
 771             if (!avahi_dns_packet_append_bytes(p, &r->data.aaaa.address, sizeof(r->data.aaaa.address)))
 772                 goto fail;
 773
 774             break;
 775
 776         default:
 777
 778             if (r->data.generic.size &&
 779                 avahi_dns_packet_append_bytes(p, r->data.generic.data, r->data.generic.size))
 780                 goto fail;
 781
 782             break;
 783     }
 784
 785
 786
 787
 788     size = avahi_dns_packet_extend(p, 0) - start;
 789     g_assert(size <= 0xFFFF);
 790
 791 /*     g_message("appended %u", size); */
 792
 793     * (guint16*) l = g_htons((guint16) size);
 794
 795     return t;
 796
 797
 798 fail:
 799     p->size = size;
 800     return NULL;
 801 }
 802
 803 gboolean avahi_dns_packet_is_empty(AvahiDnsPacket *p) {
 804     g_assert(p);
 805
 806     return p->size <= AVAHI_DNS_PACKET_HEADER_SIZE;
 807 }
 808
 809 guint avahi_dns_packet_space(AvahiDnsPacket *p) {
 810     g_assert(p);
 811
 812     g_assert(p->size <= p->max_size);
 813
 814     return p->max_size - p->size;
 815 }