4 This file is part of avahi.
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.
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.
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
26 #include <netinet/in.h>
35 AvahiDnsPacket* avahi_dns_packet_new(guint mtu) {
40 max_size = AVAHI_DNS_PACKET_MAX_SIZE;
46 if (max_size < AVAHI_DNS_PACKET_HEADER_SIZE)
47 max_size = AVAHI_DNS_PACKET_HEADER_SIZE;
49 p = g_malloc(sizeof(AvahiDnsPacket) + max_size);
50 p->size = p->rindex = AVAHI_DNS_PACKET_HEADER_SIZE;
51 p->max_size = max_size;
54 memset(AVAHI_DNS_PACKET_DATA(p), 0, p->size);
58 AvahiDnsPacket* avahi_dns_packet_new_query(guint mtu) {
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));
66 AvahiDnsPacket* avahi_dns_packet_new_response(guint mtu, gboolean aa) {
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));
74 AvahiDnsPacket* avahi_dns_packet_new_reply(AvahiDnsPacket* p, guint mtu, gboolean copy_queries, gboolean aa) {
78 r = avahi_dns_packet_new_response(mtu, aa);
81 guint n, saved_rindex;
83 saved_rindex = p->rindex;
84 p->rindex = AVAHI_DNS_PACKET_HEADER_SIZE;
86 for (n = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_QDCOUNT); n > 0; n--) {
88 gboolean unicast_response;
90 if ((k = avahi_dns_packet_consume_key(p, &unicast_response))) {
91 avahi_dns_packet_append_key(r, k, unicast_response);
96 p->rindex = saved_rindex;
98 avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_QDCOUNT, avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_QDCOUNT));
101 avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_ID, avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_ID));
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));
111 void avahi_dns_packet_free(AvahiDnsPacket *p) {
115 g_hash_table_destroy(p->name_table);
120 void avahi_dns_packet_set_field(AvahiDnsPacket *p, guint index, guint16 v) {
122 g_assert(index < AVAHI_DNS_PACKET_HEADER_SIZE);
124 ((guint16*) AVAHI_DNS_PACKET_DATA(p))[index] = g_htons(v);
127 guint16 avahi_dns_packet_get_field(AvahiDnsPacket *p, guint index) {
129 g_assert(index < AVAHI_DNS_PACKET_HEADER_SIZE);
131 return g_ntohs(((guint16*) AVAHI_DNS_PACKET_DATA(p))[index]);
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) {
158 if (**name == '\\') {
165 *(d++) = *((*name) ++);
176 guint8* avahi_dns_packet_append_name(AvahiDnsPacket *p, const gchar *name) {
177 guint8 *d, *saved_ptr = NULL;
183 saved_size = p->size;
184 saved_ptr = avahi_dns_packet_extend(p, 0);
191 /* Check whether we can compress this name. */
193 if (p->name_table && (prev = g_hash_table_lookup(p->name_table, name))) {
196 g_assert(prev >= AVAHI_DNS_PACKET_DATA(p));
197 index = (guint) (prev - AVAHI_DNS_PACKET_DATA(p));
199 g_assert(index < p->size);
201 if (index < 0x4000) {
203 if (!(t = (guint16*) avahi_dns_packet_extend(p, sizeof(guint16))))
206 *t = g_htons((0xC000 | index));
213 if (!(avahi_unescape_label(label, sizeof(label), &name)))
216 if (!(d = avahi_dns_packet_append_string(p, label)))
220 p->name_table = g_hash_table_new_full((GHashFunc) avahi_domain_hash, (GEqualFunc) avahi_domain_equal, g_free, NULL);
222 g_hash_table_insert(p->name_table, g_strdup(pname), d);
225 if (!(d = avahi_dns_packet_extend(p, 1)))
233 p->size = saved_size;
237 guint8* avahi_dns_packet_append_uint16(AvahiDnsPacket *p, guint16 v) {
241 if (!(d = avahi_dns_packet_extend(p, sizeof(guint16))))
244 *((guint16*) d) = g_htons(v);
248 guint8 *avahi_dns_packet_append_uint32(AvahiDnsPacket *p, guint32 v) {
252 if (!(d = avahi_dns_packet_extend(p, sizeof(guint32))))
255 *((guint32*) d) = g_htonl(v);
260 guint8 *avahi_dns_packet_append_bytes(AvahiDnsPacket *p, gconstpointer b, guint l) {
267 if (!(d = avahi_dns_packet_extend(p, l)))
274 guint8* avahi_dns_packet_append_string(AvahiDnsPacket *p, const gchar *s) {
281 if ((k = strlen(s)) >= 255)
284 if (!(d = avahi_dns_packet_extend(p, k+1)))
293 guint8 *avahi_dns_packet_extend(AvahiDnsPacket *p, guint l) {
298 if (p->size+l > p->max_size)
301 d = AVAHI_DNS_PACKET_DATA(p) + p->size;
307 gint avahi_dns_packet_check_valid(AvahiDnsPacket *p) {
314 flags = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS);
316 if (flags & AVAHI_DNS_FLAG_OPCODE || flags & AVAHI_DNS_FLAG_RCODE)
322 gint avahi_dns_packet_is_query(AvahiDnsPacket *p) {
325 return !(avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) & AVAHI_DNS_FLAG_QR);
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) {
335 g_assert(ret_name_length);
336 g_assert(*ret_name_length > 0);
340 while (src_length > 0) {
341 if (*src == '.' || *src == '\\') {
342 if (*ret_name_length < 3)
345 *((*ret_name) ++) = '\\';
346 (*ret_name_length) --;
349 if (*ret_name_length < 2)
352 *((*ret_name)++) = *src;
353 (*ret_name_length) --;
364 static gint consume_labels(AvahiDnsPacket *p, guint index, gchar *ret_name, guint l) {
368 g_assert(p && ret_name && l);
373 if (index+1 > p->size)
376 n = AVAHI_DNS_PACKET_DATA(p)[index];
389 } else if (n <= 63) {
390 /* Uncompressed label */
395 if (index + n > p->size)
398 if ((guint) n + 1 > l)
407 if (!(escape_label(AVAHI_DNS_PACKET_DATA(p) + index, n, &ret_name, &l)))
414 } else if ((n & 0xC0) == 0xC0) {
415 /* Compressed label */
417 if (index+2 > p->size)
420 index = ((guint) (AVAHI_DNS_PACKET_DATA(p)[index] & ~0xC0)) << 8 | AVAHI_DNS_PACKET_DATA(p)[index+1];
431 gint avahi_dns_packet_consume_name(AvahiDnsPacket *p, gchar *ret_name, guint l) {
434 if ((r = consume_labels(p, p->rindex, ret_name, l)) < 0)
441 gint avahi_dns_packet_consume_uint16(AvahiDnsPacket *p, guint16 *ret_v) {
445 if (p->rindex + sizeof(guint16) > p->size)
448 *ret_v = g_ntohs(*((guint16*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex)));
449 p->rindex += sizeof(guint16);
454 gint avahi_dns_packet_consume_uint32(AvahiDnsPacket *p, guint32 *ret_v) {
458 if (p->rindex + sizeof(guint32) > p->size)
461 *ret_v = g_ntohl(*((guint32*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex)));
462 p->rindex += sizeof(guint32);
467 gint avahi_dns_packet_consume_bytes(AvahiDnsPacket *p, gpointer ret_data, guint l) {
472 if (p->rindex + l > p->size)
475 memcpy(ret_data, AVAHI_DNS_PACKET_DATA(p) + p->rindex, l);
481 gint avahi_dns_packet_consume_string(AvahiDnsPacket *p, gchar *ret_string, guint l) {
485 g_assert(ret_string);
488 if (p->rindex >= p->size)
491 k = AVAHI_DNS_PACKET_DATA(p)[p->rindex];
493 if (p->rindex+1+k > p->size)
499 memcpy(ret_string, AVAHI_DNS_PACKET_DATA(p)+p->rindex+1, l-1);
509 gconstpointer avahi_dns_packet_get_rptr(AvahiDnsPacket *p) {
512 if (p->rindex > p->size)
515 return AVAHI_DNS_PACKET_DATA(p) + p->rindex;
518 gint avahi_dns_packet_skip(AvahiDnsPacket *p, guint length) {
521 if (p->rindex + length > p->size)
528 AvahiRecord* avahi_dns_packet_consume_record(AvahiDnsPacket *p, gboolean *ret_cache_flush) {
529 gchar name[257], buf[257];
533 AvahiRecord *r = NULL;
537 g_assert(ret_cache_flush);
539 /* g_message("consume_record()"); */
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)
549 /* g_message("name = %s, rdlength = %u", name, rdlength); */
551 *ret_cache_flush = !!(class & AVAHI_DNS_CACHE_FLUSH);
552 class &= ~AVAHI_DNS_CACHE_FLUSH;
554 start = avahi_dns_packet_get_rptr(p);
556 r = avahi_record_new_full(name, class, type);
559 case AVAHI_DNS_TYPE_PTR:
560 case AVAHI_DNS_TYPE_CNAME:
562 /* g_message("ptr"); */
564 if (avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
567 r->data.ptr.name = g_strdup(buf);
571 case AVAHI_DNS_TYPE_SRV:
573 /* g_message("srv"); */
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)
581 r->data.srv.name = g_strdup(buf);
584 case AVAHI_DNS_TYPE_HINFO:
586 /* g_message("hinfo"); */
588 if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
591 r->data.hinfo.cpu = g_strdup(buf);
593 if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
596 r->data.hinfo.os = g_strdup(buf);
599 case AVAHI_DNS_TYPE_TXT:
601 /* g_message("txt"); */
604 r->data.txt.string_list = avahi_string_list_parse(avahi_dns_packet_get_rptr(p), rdlength);
606 if (avahi_dns_packet_skip(p, rdlength) < 0)
609 r->data.txt.string_list = NULL;
613 case AVAHI_DNS_TYPE_A:
615 /* g_message("A"); */
617 if (avahi_dns_packet_consume_bytes(p, &r->data.a.address, sizeof(AvahiIPv4Address)) < 0)
622 case AVAHI_DNS_TYPE_AAAA:
624 /* g_message("aaaa"); */
626 if (avahi_dns_packet_consume_bytes(p, &r->data.aaaa.address, sizeof(AvahiIPv6Address)) < 0)
633 /* g_message("generic"); */
637 r->data.generic.data = g_memdup(avahi_dns_packet_get_rptr(p), rdlength);
639 if (avahi_dns_packet_skip(p, rdlength) < 0)
646 /* g_message("%i == %u ?", (guint8*) avahi_dns_packet_get_rptr(p) - (guint8*) start, rdlength); */
648 /* Check if we read enough data */
649 if ((guint8*) avahi_dns_packet_get_rptr(p) - (guint8*) start != rdlength)
658 avahi_record_unref(r);
663 AvahiKey* avahi_dns_packet_consume_key(AvahiDnsPacket *p, gboolean *ret_unicast_response) {
668 g_assert(ret_unicast_response);
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)
675 *ret_unicast_response = !!(class & AVAHI_DNS_UNICAST_RESPONSE);
676 class &= ~AVAHI_DNS_UNICAST_RESPONSE;
678 return avahi_key_new(name, class, type);
681 guint8* avahi_dns_packet_append_key(AvahiDnsPacket *p, AvahiKey *k, gboolean unicast_response) {
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))) {
700 guint8* avahi_dns_packet_append_record(AvahiDnsPacket *p, AvahiRecord *r, gboolean cache_flush, guint max_ttl) {
701 guint8 *t, *l, *start;
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)))
716 start = avahi_dns_packet_extend(p, 0);
718 switch (r->key->type) {
720 case AVAHI_DNS_TYPE_PTR:
721 case AVAHI_DNS_TYPE_CNAME :
723 if (!(avahi_dns_packet_append_name(p, r->data.ptr.name)))
728 case AVAHI_DNS_TYPE_SRV:
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))
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))
745 case AVAHI_DNS_TYPE_TXT: {
750 size = avahi_string_list_serialize(r->data.txt.string_list, NULL, 0);
752 /* g_message("appending string: %u %p", size, r->data.txt.string_list); */
754 if (!(data = avahi_dns_packet_extend(p, size)))
757 avahi_string_list_serialize(r->data.txt.string_list, data, size);
762 case AVAHI_DNS_TYPE_A:
764 if (!avahi_dns_packet_append_bytes(p, &r->data.a.address, sizeof(r->data.a.address)))
769 case AVAHI_DNS_TYPE_AAAA:
771 if (!avahi_dns_packet_append_bytes(p, &r->data.aaaa.address, sizeof(r->data.aaaa.address)))
778 if (r->data.generic.size &&
779 avahi_dns_packet_append_bytes(p, r->data.generic.data, r->data.generic.size))
788 size = avahi_dns_packet_extend(p, 0) - start;
789 g_assert(size <= 0xFFFF);
791 /* g_message("appended %u", size); */
793 * (guint16*) l = g_htons((guint16) size);
803 gboolean avahi_dns_packet_is_empty(AvahiDnsPacket *p) {
806 return p->size <= AVAHI_DNS_PACKET_HEADER_SIZE;
809 guint avahi_dns_packet_space(AvahiDnsPacket *p) {
812 g_assert(p->size <= p->max_size);
814 return p->max_size - p->size;