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) {
  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, 0, 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);
  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                                (aa ? AVAHI_DNS_FLAG_AA : 0));
 107
 108     return r;
 109 }
 110
 111
 112 void avahi_dns_packet_free(AvahiDnsPacket *p) {
 113     g_assert(p);
 114
 115     if (p->name_table)
 116         g_hash_table_destroy(p->name_table);
 117
 118     g_free(p);
 119 }
 120
 121 void avahi_dns_packet_set_field(AvahiDnsPacket *p, guint index, guint16 v) {
 122     g_assert(p);
 123     g_assert(index < AVAHI_DNS_PACKET_HEADER_SIZE);
 124
 125     ((guint16*) AVAHI_DNS_PACKET_DATA(p))[index] = g_htons(v);
 126 }
 127
 128 guint16 avahi_dns_packet_get_field(AvahiDnsPacket *p, guint index) {
 129     g_assert(p);
 130     g_assert(index < AVAHI_DNS_PACKET_HEADER_SIZE);
 131
 132     return g_ntohs(((guint16*) AVAHI_DNS_PACKET_DATA(p))[index]);
 133 }
 134
 135 /* Read the first label from string *name, unescape "\" and write it to dest */
 136 gchar *avahi_unescape_label(gchar *dest, guint size, const gchar **name) {
 137     guint i = 0;
 138     gchar *d;
 139
 140     g_assert(dest);
 141     g_assert(size > 0);
 142     g_assert(name);
 143     g_assert(*name);
 144
 145     d = dest;
 146
 147     for (;;) {
 148         if (i >= size)
 149             return NULL;
 150
 151         if (**name == '.') {
 152             (*name)++;
 153             break;
 154         }
 155
 156         if (**name == 0)
 157             break;
 158
 159         if (**name == '\\') {
 160             (*name) ++;
 161
 162             if (**name == 0)
 163                 break;
 164         }
 165
 166         *(d++) = *((*name) ++);
 167         i++;
 168     }
 169
 170     g_assert(i < size);
 171
 172     *d = 0;
 173
 174     return dest;
 175 }
 176
 177 guint8* avahi_dns_packet_append_name(AvahiDnsPacket *p, const gchar *name) {
 178     guint8 *d, *saved_ptr = NULL;
 179     guint saved_size;
 180
 181     g_assert(p);
 182     g_assert(name);
 183
 184     saved_size = p->size;
 185     saved_ptr = avahi_dns_packet_extend(p, 0);
 186
 187     while (*name) {
 188         guint8* prev;
 189         const gchar *pname;
 190         gchar label[64];
 191
 192         /* Check whether we can compress this name. */
 193
 194         if (p->name_table && (prev = g_hash_table_lookup(p->name_table, name))) {
 195             guint index;
 196
 197             g_assert(prev >= AVAHI_DNS_PACKET_DATA(p));
 198             index = (guint) (prev - AVAHI_DNS_PACKET_DATA(p));
 199
 200             g_assert(index < p->size);
 201
 202             if (index < 0x4000) {
 203                 guint16 *t;
 204                 if (!(t = (guint16*) avahi_dns_packet_extend(p, sizeof(guint16))))
 205                     return NULL;
 206
 207                 *t = g_htons((0xC000 | index));
 208                 return saved_ptr;
 209             }
 210         }
 211
 212         pname = name;
 213
 214         if (!(avahi_unescape_label(label, sizeof(label), &name)))
 215             goto fail;
 216
 217         if (!(d = avahi_dns_packet_append_string(p, label)))
 218             goto fail;
 219
 220         if (!p->name_table)
 221             p->name_table = g_hash_table_new_full((GHashFunc) avahi_domain_hash, (GEqualFunc) avahi_domain_equal, g_free, NULL);
 222
 223         g_hash_table_insert(p->name_table, g_strdup(pname), d);
 224     }
 225
 226     if (!(d = avahi_dns_packet_extend(p, 1)))
 227         goto fail;
 228
 229     *d = 0;
 230
 231     return saved_ptr;
 232
 233 fail:
 234     p->size = saved_size;
 235     return NULL;
 236 }
 237
 238 guint8* avahi_dns_packet_append_uint16(AvahiDnsPacket *p, guint16 v) {
 239     guint8 *d;
 240     g_assert(p);
 241
 242     if (!(d = avahi_dns_packet_extend(p, sizeof(guint16))))
 243         return NULL;
 244
 245     *((guint16*) d) = g_htons(v);
 246     return d;
 247 }
 248
 249 guint8 *avahi_dns_packet_append_uint32(AvahiDnsPacket *p, guint32 v) {
 250     guint8 *d;
 251     g_assert(p);
 252
 253     if (!(d = avahi_dns_packet_extend(p, sizeof(guint32))))
 254         return NULL;
 255
 256     *((guint32*) d) = g_htonl(v);
 257
 258     return d;
 259 }
 260
 261 guint8 *avahi_dns_packet_append_bytes(AvahiDnsPacket  *p, gconstpointer b, guint l) {
 262     guint8* d;
 263
 264     g_assert(p);
 265     g_assert(b);
 266     g_assert(l);
 267
 268     if (!(d = avahi_dns_packet_extend(p, l)))
 269         return NULL;
 270
 271     memcpy(d, b, l);
 272     return d;
 273 }
 274
 275 guint8* avahi_dns_packet_append_string(AvahiDnsPacket *p, const gchar *s) {
 276     guint8* d;
 277     guint k;
 278
 279     g_assert(p);
 280     g_assert(s);
 281
 282     if ((k = strlen(s)) >= 255)
 283         k = 255;
 284
 285     if (!(d = avahi_dns_packet_extend(p, k+1)))
 286         return NULL;
 287
 288     *d = (guint8) k;
 289     memcpy(d+1, s, k);
 290
 291     return d;
 292 }
 293
 294 guint8 *avahi_dns_packet_extend(AvahiDnsPacket *p, guint l) {
 295     guint8 *d;
 296
 297     g_assert(p);
 298
 299     if (p->size+l > p->max_size)
 300         return NULL;
 301
 302     d = AVAHI_DNS_PACKET_DATA(p) + p->size;
 303     p->size += l;
 304
 305     return d;
 306 }
 307
 308 gint avahi_dns_packet_check_valid(AvahiDnsPacket *p) {
 309     guint16 flags;
 310     g_assert(p);
 311
 312     if (p->size < 12)
 313         return -1;
 314
 315     flags = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS);
 316
 317     if (flags & AVAHI_DNS_FLAG_OPCODE || flags & AVAHI_DNS_FLAG_RCODE)
 318         return -1;
 319
 320     return 0;
 321 }
 322
 323 gint avahi_dns_packet_is_query(AvahiDnsPacket *p) {
 324     g_assert(p);
 325
 326     return !(avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) & AVAHI_DNS_FLAG_QR);
 327 }
 328
 329 /* Read a label from a DNS packet, escape "\" and ".", append \0 */
 330 static gchar *escape_label(guint8* src, guint src_length, gchar **ret_name, guint *ret_name_length) {
 331     gchar *r;
 332
 333     g_assert(src);
 334     g_assert(ret_name);
 335     g_assert(*ret_name);
 336     g_assert(ret_name_length);
 337     g_assert(*ret_name_length > 0);
 338
 339     r = *ret_name;
 340
 341     while (src_length > 0) {
 342         if (*src == '.' || *src == '\\') {
 343             if (*ret_name_length < 3)
 344                 return NULL;
 345
 346             *((*ret_name) ++) = '\\';
 347             (*ret_name_length) --;
 348         }
 349
 350         if (*ret_name_length < 2)
 351             return NULL;
 352
 353         *((*ret_name)++) = *src;
 354         (*ret_name_length) --;
 355
 356         src_length --;
 357         src++;
 358     }
 359
 360     **ret_name = 0;
 361
 362     return r;
 363 }
 364
 365 static gint consume_labels(AvahiDnsPacket *p, guint index, gchar *ret_name, guint l) {
 366     gint ret = 0;
 367     int compressed = 0;
 368     int first_label = 1;
 369     g_assert(p && ret_name && l);
 370
 371     for (;;) {
 372         guint8 n;
 373
 374         if (index+1 > p->size)
 375             return -1;
 376
 377         n = AVAHI_DNS_PACKET_DATA(p)[index];
 378
 379         if (!n) {
 380             index++;
 381             if (!compressed)
 382                 ret++;
 383
 384             if (l < 1)
 385                 return -1;
 386             *ret_name = 0;
 387
 388             return ret;
 389
 390         } else if (n <= 63) {
 391             /* Uncompressed label */
 392             index++;
 393             if (!compressed)
 394                 ret++;
 395
 396             if (index + n > p->size)
 397                 return -1;
 398
 399             if ((guint) n + 1 > l)
 400                 return -1;
 401
 402             if (!first_label) {
 403                 *(ret_name++) = '.';
 404                 l--;
 405             } else
 406                 first_label = 0;
 407
 408             if (!(escape_label(AVAHI_DNS_PACKET_DATA(p) + index, n, &ret_name, &l)))
 409                 return -1;
 410
 411             index += n;
 412
 413             if (!compressed)
 414                 ret += n;
 415         } else if ((n & 0xC0) == 0xC0) {
 416             /* Compressed label */
 417
 418             if (index+2 > p->size)
 419                 return -1;
 420
 421             index = ((guint) (AVAHI_DNS_PACKET_DATA(p)[index] & ~0xC0)) << 8 | AVAHI_DNS_PACKET_DATA(p)[index+1];
 422
 423             if (!compressed)
 424                 ret += 2;
 425
 426             compressed = 1;
 427         } else
 428             return -1;
 429     }
 430 }
 431
 432 gint avahi_dns_packet_consume_name(AvahiDnsPacket *p, gchar *ret_name, guint l) {
 433     gint r;
 434
 435     if ((r = consume_labels(p, p->rindex, ret_name, l)) < 0)
 436         return -1;
 437
 438     p->rindex += r;
 439     return 0;
 440 }
 441
 442 gint avahi_dns_packet_consume_uint16(AvahiDnsPacket *p, guint16 *ret_v) {
 443     g_assert(p);
 444     g_assert(ret_v);
 445
 446     if (p->rindex + sizeof(guint16) > p->size)
 447         return -1;
 448
 449     *ret_v = g_ntohs(*((guint16*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex)));
 450     p->rindex += sizeof(guint16);
 451
 452     return 0;
 453 }
 454
 455 gint avahi_dns_packet_consume_uint32(AvahiDnsPacket *p, guint32 *ret_v) {
 456     g_assert(p);
 457     g_assert(ret_v);
 458
 459     if (p->rindex + sizeof(guint32) > p->size)
 460         return -1;
 461
 462     *ret_v = g_ntohl(*((guint32*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex)));
 463     p->rindex += sizeof(guint32);
 464
 465     return 0;
 466 }
 467
 468 gint avahi_dns_packet_consume_bytes(AvahiDnsPacket *p, gpointer ret_data, guint l) {
 469     g_assert(p);
 470     g_assert(ret_data);
 471     g_assert(l > 0);
 472
 473     if (p->rindex + l > p->size)
 474         return -1;
 475
 476     memcpy(ret_data, AVAHI_DNS_PACKET_DATA(p) + p->rindex, l);
 477     p->rindex += l;
 478
 479     return 0;
 480 }
 481
 482 gint avahi_dns_packet_consume_string(AvahiDnsPacket *p, gchar *ret_string, guint l) {
 483     guint k;
 484
 485     g_assert(p);
 486     g_assert(ret_string);
 487     g_assert(l > 0);
 488
 489     if (p->rindex >= p->size)
 490         return -1;
 491
 492     k = AVAHI_DNS_PACKET_DATA(p)[p->rindex];
 493
 494     if (p->rindex+1+k > p->size)
 495         return -1;
 496
 497     if (l > k+1)
 498         l = k+1;
 499
 500     memcpy(ret_string, AVAHI_DNS_PACKET_DATA(p)+p->rindex+1, l-1);
 501     ret_string[l-1] = 0;
 502
 503
 504     p->rindex += 1+k;
 505
 506     return 0;
 507
 508 }
 509
 510 gconstpointer avahi_dns_packet_get_rptr(AvahiDnsPacket *p) {
 511     g_assert(p);
 512
 513     if (p->rindex > p->size)
 514         return NULL;
 515
 516     return AVAHI_DNS_PACKET_DATA(p) + p->rindex;
 517 }
 518
 519 gint avahi_dns_packet_skip(AvahiDnsPacket *p, guint length) {
 520     g_assert(p);
 521
 522     if (p->rindex + length > p->size)
 523         return -1;
 524
 525     p->rindex += length;
 526     return 0;
 527 }
 528
 529 AvahiRecord* avahi_dns_packet_consume_record(AvahiDnsPacket *p, gboolean *ret_cache_flush) {
 530     gchar name[257], buf[257];
 531     guint16 type, class;
 532     guint32 ttl;
 533     guint16 rdlength;
 534     AvahiRecord *r = NULL;
 535     gconstpointer start;
 536
 537     g_assert(p);
 538     g_assert(ret_cache_flush);
 539
 540 /*     g_message("consume_record()"); */
 541
 542     if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
 543         avahi_dns_packet_consume_uint16(p, &type) < 0 ||
 544         avahi_dns_packet_consume_uint16(p, &class) < 0 ||
 545         avahi_dns_packet_consume_uint32(p, &ttl) < 0 ||
 546         avahi_dns_packet_consume_uint16(p, &rdlength) < 0 ||
 547         p->rindex + rdlength > p->size)
 548         goto fail;
 549
 550 /*     g_message("name = %s, rdlength = %u", name, rdlength); */
 551
 552     *ret_cache_flush = !!(class & AVAHI_DNS_CACHE_FLUSH);
 553     class &= ~AVAHI_DNS_CACHE_FLUSH;
 554
 555     start = avahi_dns_packet_get_rptr(p);
 556
 557     r = avahi_record_new_full(name, class, type);
 558
 559     switch (type) {
 560         case AVAHI_DNS_TYPE_PTR:
 561         case AVAHI_DNS_TYPE_CNAME:
 562
 563 /*             g_message("ptr"); */
 564
 565             if (avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
 566                 goto fail;
 567
 568             r->data.ptr.name = g_strdup(buf);
 569             break;
 570
 571
 572         case AVAHI_DNS_TYPE_SRV:
 573
 574 /*             g_message("srv"); */
 575
 576             if (avahi_dns_packet_consume_uint16(p, &r->data.srv.priority) < 0 ||
 577                 avahi_dns_packet_consume_uint16(p, &r->data.srv.weight) < 0 ||
 578                 avahi_dns_packet_consume_uint16(p, &r->data.srv.port) < 0 ||
 579                 avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
 580                 goto fail;
 581
 582             r->data.srv.name = g_strdup(buf);
 583             break;
 584
 585         case AVAHI_DNS_TYPE_HINFO:
 586
 587 /*             g_message("hinfo"); */
 588
 589             if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
 590                 goto fail;
 591
 592             r->data.hinfo.cpu = g_strdup(buf);
 593
 594             if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
 595                 goto fail;
 596
 597             r->data.hinfo.os = g_strdup(buf);
 598             break;
 599
 600         case AVAHI_DNS_TYPE_TXT:
 601
 602 /*             g_message("txt"); */
 603
 604             if (rdlength > 0) {
 605                 r->data.txt.string_list = avahi_string_list_parse(avahi_dns_packet_get_rptr(p), rdlength);
 606
 607                 if (avahi_dns_packet_skip(p, rdlength) < 0)
 608                     goto fail;
 609             } else
 610                 r->data.txt.string_list = NULL;
 611
 612             break;
 613
 614         case AVAHI_DNS_TYPE_A:
 615
 616 /*             g_message("A"); */
 617
 618             if (avahi_dns_packet_consume_bytes(p, &r->data.a.address, sizeof(AvahiIPv4Address)) < 0)
 619                 goto fail;
 620
 621             break;
 622
 623         case AVAHI_DNS_TYPE_AAAA:
 624
 625 /*             g_message("aaaa"); */
 626
 627             if (avahi_dns_packet_consume_bytes(p, &r->data.aaaa.address, sizeof(AvahiIPv6Address)) < 0)
 628                 goto fail;
 629
 630             break;
 631
 632         default:
 633
 634 /*             g_message("generic"); */
 635
 636             if (rdlength > 0) {
 637
 638                 r->data.generic.data = g_memdup(avahi_dns_packet_get_rptr(p), rdlength);
 639
 640                 if (avahi_dns_packet_skip(p, rdlength) < 0)
 641                     goto fail;
 642             }
 643
 644             break;
 645     }
 646
 647 /*     g_message("%i == %u ?", (guint8*) avahi_dns_packet_get_rptr(p) - (guint8*) start, rdlength); */
 648
 649     /* Check if we read enough data */
 650     if ((guint8*) avahi_dns_packet_get_rptr(p) - (guint8*) start != rdlength)
 651         goto fail;
 652
 653     r->ttl = ttl;
 654
 655     return r;
 656
 657 fail:
 658     if (r)
 659         avahi_record_unref(r);
 660
 661     return NULL;
 662 }
 663
 664 AvahiKey* avahi_dns_packet_consume_key(AvahiDnsPacket *p, gboolean *ret_unicast_response) {
 665     gchar name[256];
 666     guint16 type, class;
 667
 668     g_assert(p);
 669     g_assert(ret_unicast_response);
 670
 671     if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
 672         avahi_dns_packet_consume_uint16(p, &type) < 0 ||
 673         avahi_dns_packet_consume_uint16(p, &class) < 0)
 674         return NULL;
 675
 676     *ret_unicast_response = !!(class & AVAHI_DNS_UNICAST_RESPONSE);
 677     class &= ~AVAHI_DNS_UNICAST_RESPONSE;
 678
 679     return avahi_key_new(name, class, type);
 680 }
 681
 682 guint8* avahi_dns_packet_append_key(AvahiDnsPacket *p, AvahiKey *k, gboolean unicast_response) {
 683     guint8 *t;
 684     guint size;
 685
 686     g_assert(p);
 687     g_assert(k);
 688
 689     size = p->size;
 690
 691     if (!(t = avahi_dns_packet_append_name(p, k->name)) ||
 692         !avahi_dns_packet_append_uint16(p, k->type) ||
 693         !avahi_dns_packet_append_uint16(p, k->class | (unicast_response ? AVAHI_DNS_UNICAST_RESPONSE : 0))) {
 694         p->size = size;
 695         return NULL;
 696     }
 697
 698     return t;
 699 }
 700
 701 guint8* avahi_dns_packet_append_record(AvahiDnsPacket *p, AvahiRecord *r, gboolean cache_flush, guint max_ttl) {
 702     guint8 *t, *l, *start;
 703     guint size;
 704
 705     g_assert(p);
 706     g_assert(r);
 707
 708     size = p->size;
 709
 710     if (!(t = avahi_dns_packet_append_name(p, r->key->name)) ||
 711         !avahi_dns_packet_append_uint16(p, r->key->type) ||
 712         !avahi_dns_packet_append_uint16(p, cache_flush ? (r->key->class | AVAHI_DNS_CACHE_FLUSH) : (r->key->class &~ AVAHI_DNS_CACHE_FLUSH)) ||
 713         !avahi_dns_packet_append_uint32(p, (max_ttl && r->ttl > max_ttl) ? max_ttl : r->ttl) ||
 714         !(l = avahi_dns_packet_append_uint16(p, 0)))
 715         goto fail;
 716
 717     start = avahi_dns_packet_extend(p, 0);
 718
 719     switch (r->key->type) {
 720
 721         case AVAHI_DNS_TYPE_PTR:
 722         case AVAHI_DNS_TYPE_CNAME :
 723
 724             if (!(avahi_dns_packet_append_name(p, r->data.ptr.name)))
 725                 goto fail;
 726
 727             break;
 728
 729         case AVAHI_DNS_TYPE_SRV:
 730
 731             if (!avahi_dns_packet_append_uint16(p, r->data.srv.priority) ||
 732                 !avahi_dns_packet_append_uint16(p, r->data.srv.weight) ||
 733                 !avahi_dns_packet_append_uint16(p, r->data.srv.port) ||
 734                 !avahi_dns_packet_append_name(p, r->data.srv.name))
 735                 goto fail;
 736
 737             break;
 738
 739         case AVAHI_DNS_TYPE_HINFO:
 740             if (!avahi_dns_packet_append_string(p, r->data.hinfo.cpu) ||
 741                 !avahi_dns_packet_append_string(p, r->data.hinfo.os))
 742                 goto fail;
 743
 744             break;
 745
 746         case AVAHI_DNS_TYPE_TXT: {
 747
 748             guint8 *data;
 749             guint size;
 750
 751             size = avahi_string_list_serialize(r->data.txt.string_list, NULL, 0);
 752
 753 /*             g_message("appending string: %u %p", size, r->data.txt.string_list); */
 754
 755             if (!(data = avahi_dns_packet_extend(p, size)))
 756                 goto fail;
 757
 758             avahi_string_list_serialize(r->data.txt.string_list, data, size);
 759             break;
 760         }
 761
 762
 763         case AVAHI_DNS_TYPE_A:
 764
 765             if (!avahi_dns_packet_append_bytes(p, &r->data.a.address, sizeof(r->data.a.address)))
 766                 goto fail;
 767
 768             break;
 769
 770         case AVAHI_DNS_TYPE_AAAA:
 771
 772             if (!avahi_dns_packet_append_bytes(p, &r->data.aaaa.address, sizeof(r->data.aaaa.address)))
 773                 goto fail;
 774
 775             break;
 776
 777         default:
 778
 779             if (r->data.generic.size &&
 780                 avahi_dns_packet_append_bytes(p, r->data.generic.data, r->data.generic.size))
 781                 goto fail;
 782
 783             break;
 784     }
 785
 786
 787
 788
 789     size = avahi_dns_packet_extend(p, 0) - start;
 790     g_assert(size <= 0xFFFF);
 791
 792 /*     g_message("appended %u", size); */
 793
 794     * (guint16*) l = g_htons((guint16) size);
 795
 796     return t;
 797
 798
 799 fail:
 800     p->size = size;
 801     return NULL;
 802 }
 803
 804 gboolean avahi_dns_packet_is_empty(AvahiDnsPacket *p) {
 805     g_assert(p);
 806
 807     return p->size <= AVAHI_DNS_PACKET_HEADER_SIZE;
 808 }
 809
 810 guint avahi_dns_packet_space(AvahiDnsPacket *p) {
 811     g_assert(p);
 812
 813     g_assert(p->size <= p->max_size);
 814
 815     return p->max_size - p->size;
 816 }