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
31 #include <netinet/in.h>
33 #include <avahi-common/defs.h>
34 #include <avahi-common/domain.h>
35 #include <avahi-common/malloc.h>
40 AvahiDnsPacket* avahi_dns_packet_new(unsigned mtu) {
45 max_size = AVAHI_DNS_PACKET_SIZE_MAX;
46 else if (mtu >= AVAHI_DNS_PACKET_EXTRA_SIZE)
47 max_size = mtu - AVAHI_DNS_PACKET_EXTRA_SIZE;
51 if (max_size < AVAHI_DNS_PACKET_HEADER_SIZE)
52 max_size = AVAHI_DNS_PACKET_HEADER_SIZE;
54 if (!(p = avahi_malloc(sizeof(AvahiDnsPacket) + max_size)))
57 p->size = p->rindex = AVAHI_DNS_PACKET_HEADER_SIZE;
58 p->max_size = max_size;
62 memset(AVAHI_DNS_PACKET_DATA(p), 0, p->size);
66 AvahiDnsPacket* avahi_dns_packet_new_query(unsigned mtu) {
69 if (!(p = avahi_dns_packet_new(mtu)))
72 avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_FLAGS, AVAHI_DNS_FLAGS(0, 0, 0, 0, 0, 0, 0, 0, 0, 0));
76 AvahiDnsPacket* avahi_dns_packet_new_response(unsigned mtu, int aa) {
79 if (!(p = avahi_dns_packet_new(mtu)))
82 avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_FLAGS, AVAHI_DNS_FLAGS(1, 0, aa, 0, 0, 0, 0, 0, 0, 0));
86 AvahiDnsPacket* avahi_dns_packet_new_reply(AvahiDnsPacket* p, unsigned mtu, int copy_queries, int aa) {
90 if (!(r = avahi_dns_packet_new_response(mtu, aa)))
94 unsigned saved_rindex;
97 saved_rindex = p->rindex;
98 p->rindex = AVAHI_DNS_PACKET_HEADER_SIZE;
100 for (n = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_QDCOUNT); n > 0; n--) {
102 int unicast_response;
104 if ((k = avahi_dns_packet_consume_key(p, &unicast_response))) {
105 avahi_dns_packet_append_key(r, k, unicast_response);
110 p->rindex = saved_rindex;
112 avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_QDCOUNT, avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_QDCOUNT));
115 avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_ID, avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_ID));
117 avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_FLAGS,
118 (avahi_dns_packet_get_field(r, AVAHI_DNS_FIELD_FLAGS) & ~AVAHI_DNS_FLAG_OPCODE) |
119 (avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) & AVAHI_DNS_FLAG_OPCODE));
125 void avahi_dns_packet_free(AvahiDnsPacket *p) {
129 avahi_hashmap_free(p->name_table);
134 void avahi_dns_packet_set_field(AvahiDnsPacket *p, unsigned idx, uint16_t v) {
136 assert(idx < AVAHI_DNS_PACKET_HEADER_SIZE);
138 ((uint16_t*) AVAHI_DNS_PACKET_DATA(p))[idx] = htons(v);
141 uint16_t avahi_dns_packet_get_field(AvahiDnsPacket *p, unsigned idx) {
143 assert(idx < AVAHI_DNS_PACKET_HEADER_SIZE);
145 return ntohs(((uint16_t*) AVAHI_DNS_PACKET_DATA(p))[idx]);
148 void avahi_dns_packet_inc_field(AvahiDnsPacket *p, unsigned idx) {
150 assert(idx < AVAHI_DNS_PACKET_HEADER_SIZE);
152 avahi_dns_packet_set_field(p, idx, avahi_dns_packet_get_field(p, idx) + 1);
155 uint8_t* avahi_dns_packet_append_name(AvahiDnsPacket *p, const char *name) {
156 uint8_t *d, *saved_ptr = NULL;
162 saved_size = p->size;
163 saved_ptr = avahi_dns_packet_extend(p, 0);
170 /* Check whether we can compress this name. */
172 if (p->name_table && (prev = avahi_hashmap_lookup(p->name_table, name))) {
175 assert(prev >= AVAHI_DNS_PACKET_DATA(p));
176 idx = (unsigned) (prev - AVAHI_DNS_PACKET_DATA(p));
178 assert(idx < p->size);
182 if (!(t = (uint8_t*) avahi_dns_packet_extend(p, sizeof(uint16_t))))
185 t[0] = (uint8_t) ((0xC000 | idx) >> 8);
186 t[1] = (uint8_t) idx;
193 if (!(avahi_unescape_label(&name, label, sizeof(label))))
196 if (!(d = avahi_dns_packet_append_string(p, label)))
200 /* This works only for normalized domain names */
201 p->name_table = avahi_hashmap_new(avahi_string_hash, avahi_string_equal, avahi_free, NULL);
203 if (!(u = avahi_strdup(pname)))
204 avahi_log_error("avahi_strdup() failed.");
206 avahi_hashmap_insert(p->name_table, u, d);
209 if (!(d = avahi_dns_packet_extend(p, 1)))
217 p->size = saved_size;
221 uint8_t* avahi_dns_packet_append_uint16(AvahiDnsPacket *p, uint16_t v) {
225 if (!(d = avahi_dns_packet_extend(p, sizeof(uint16_t))))
228 d[0] = (uint8_t) (v >> 8);
233 uint8_t *avahi_dns_packet_append_uint32(AvahiDnsPacket *p, uint32_t v) {
237 if (!(d = avahi_dns_packet_extend(p, sizeof(uint32_t))))
240 d[0] = (uint8_t) (v >> 24);
241 d[1] = (uint8_t) (v >> 16);
242 d[2] = (uint8_t) (v >> 8);
248 uint8_t *avahi_dns_packet_append_bytes(AvahiDnsPacket *p, const void *b, size_t l) {
255 if (!(d = avahi_dns_packet_extend(p, l)))
262 uint8_t* avahi_dns_packet_append_string(AvahiDnsPacket *p, const char *s) {
269 if ((k = strlen(s)) >= 255)
272 if (!(d = avahi_dns_packet_extend(p, k+1)))
281 uint8_t *avahi_dns_packet_extend(AvahiDnsPacket *p, size_t l) {
286 if (p->size+l > p->max_size)
289 d = AVAHI_DNS_PACKET_DATA(p) + p->size;
295 int avahi_dns_packet_check_valid(AvahiDnsPacket *p) {
299 if (p->size < AVAHI_DNS_PACKET_HEADER_SIZE)
302 flags = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS);
304 if (flags & AVAHI_DNS_FLAG_OPCODE)
310 int avahi_dns_packet_check_valid_multicast(AvahiDnsPacket *p) {
314 if (avahi_dns_packet_check_valid(p) < 0)
317 flags = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS);
319 if (flags & AVAHI_DNS_FLAG_RCODE)
325 int avahi_dns_packet_is_query(AvahiDnsPacket *p) {
328 return !(avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) & AVAHI_DNS_FLAG_QR);
331 static int consume_labels(AvahiDnsPacket *p, unsigned idx, char *ret_name, size_t l) {
337 assert(p && ret_name && l);
339 for (i = 0; i < AVAHI_DNS_LABELS_MAX; i++) {
345 n = AVAHI_DNS_PACKET_DATA(p)[idx];
358 } else if (n <= 63) {
359 /* Uncompressed label */
364 if (idx + n > p->size)
367 if ((size_t) n + 1 > l)
376 if (!(avahi_escape_label((char*) AVAHI_DNS_PACKET_DATA(p) + idx, n, &ret_name, &l)))
383 } else if ((n & 0xC0) == 0xC0) {
384 /* Compressed label */
389 label_ptr = ((unsigned) (AVAHI_DNS_PACKET_DATA(p)[idx] & ~0xC0)) << 8 | AVAHI_DNS_PACKET_DATA(p)[idx+1];
391 if ((label_ptr < AVAHI_DNS_PACKET_HEADER_SIZE) || (label_ptr >= idx))
405 int avahi_dns_packet_consume_name(AvahiDnsPacket *p, char *ret_name, size_t l) {
408 if ((r = consume_labels(p, p->rindex, ret_name, l)) < 0)
415 int avahi_dns_packet_consume_uint16(AvahiDnsPacket *p, uint16_t *ret_v) {
421 if (p->rindex + sizeof(uint16_t) > p->size)
424 d = (uint8_t*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex);
425 *ret_v = (d[0] << 8) | d[1];
426 p->rindex += sizeof(uint16_t);
431 int avahi_dns_packet_consume_uint32(AvahiDnsPacket *p, uint32_t *ret_v) {
437 if (p->rindex + sizeof(uint32_t) > p->size)
440 d = (uint8_t*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex);
441 *ret_v = (d[0] << 24) | (d[1] << 16) | (d[2] << 8) | d[3];
442 p->rindex += sizeof(uint32_t);
447 int avahi_dns_packet_consume_bytes(AvahiDnsPacket *p, void * ret_data, size_t l) {
452 if (p->rindex + l > p->size)
455 memcpy(ret_data, AVAHI_DNS_PACKET_DATA(p) + p->rindex, l);
461 int avahi_dns_packet_consume_string(AvahiDnsPacket *p, char *ret_string, size_t l) {
468 if (p->rindex >= p->size)
471 k = AVAHI_DNS_PACKET_DATA(p)[p->rindex];
473 if (p->rindex+1+k > p->size)
479 memcpy(ret_string, AVAHI_DNS_PACKET_DATA(p)+p->rindex+1, l-1);
487 const void* avahi_dns_packet_get_rptr(AvahiDnsPacket *p) {
490 if (p->rindex > p->size)
493 return AVAHI_DNS_PACKET_DATA(p) + p->rindex;
496 int avahi_dns_packet_skip(AvahiDnsPacket *p, size_t length) {
499 if (p->rindex + length > p->size)
506 static int parse_rdata(AvahiDnsPacket *p, AvahiRecord *r, uint16_t rdlength) {
507 char buf[AVAHI_DOMAIN_NAME_MAX];
513 start = avahi_dns_packet_get_rptr(p);
515 switch (r->key->type) {
516 case AVAHI_DNS_TYPE_PTR:
517 case AVAHI_DNS_TYPE_CNAME:
518 case AVAHI_DNS_TYPE_NS:
520 if (avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
523 r->data.ptr.name = avahi_strdup(buf);
527 case AVAHI_DNS_TYPE_SRV:
529 if (avahi_dns_packet_consume_uint16(p, &r->data.srv.priority) < 0 ||
530 avahi_dns_packet_consume_uint16(p, &r->data.srv.weight) < 0 ||
531 avahi_dns_packet_consume_uint16(p, &r->data.srv.port) < 0 ||
532 avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
535 r->data.srv.name = avahi_strdup(buf);
538 case AVAHI_DNS_TYPE_HINFO:
540 if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
543 r->data.hinfo.cpu = avahi_strdup(buf);
545 if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
548 r->data.hinfo.os = avahi_strdup(buf);
551 case AVAHI_DNS_TYPE_TXT:
554 if (avahi_string_list_parse(avahi_dns_packet_get_rptr(p), rdlength, &r->data.txt.string_list) < 0)
557 if (avahi_dns_packet_skip(p, rdlength) < 0)
560 r->data.txt.string_list = NULL;
564 case AVAHI_DNS_TYPE_A:
566 /* avahi_log_debug("A"); */
568 if (avahi_dns_packet_consume_bytes(p, &r->data.a.address, sizeof(AvahiIPv4Address)) < 0)
573 case AVAHI_DNS_TYPE_AAAA:
575 /* avahi_log_debug("aaaa"); */
577 if (avahi_dns_packet_consume_bytes(p, &r->data.aaaa.address, sizeof(AvahiIPv6Address)) < 0)
584 /* avahi_log_debug("generic"); */
588 r->data.generic.data = avahi_memdup(avahi_dns_packet_get_rptr(p), rdlength);
590 if (avahi_dns_packet_skip(p, rdlength) < 0)
597 /* Check if we read enough data */
598 if ((const uint8_t*) avahi_dns_packet_get_rptr(p) - (const uint8_t*) start != rdlength)
604 AvahiRecord* avahi_dns_packet_consume_record(AvahiDnsPacket *p, int *ret_cache_flush) {
605 char name[AVAHI_DOMAIN_NAME_MAX];
606 uint16_t type, class;
609 AvahiRecord *r = NULL;
613 if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
614 avahi_dns_packet_consume_uint16(p, &type) < 0 ||
615 avahi_dns_packet_consume_uint16(p, &class) < 0 ||
616 avahi_dns_packet_consume_uint32(p, &ttl) < 0 ||
617 avahi_dns_packet_consume_uint16(p, &rdlength) < 0 ||
618 p->rindex + rdlength > p->size)
622 *ret_cache_flush = !!(class & AVAHI_DNS_CACHE_FLUSH);
623 class &= ~AVAHI_DNS_CACHE_FLUSH;
625 if (!(r = avahi_record_new_full(name, class, type, ttl)))
628 if (parse_rdata(p, r, rdlength) < 0)
631 if (!avahi_record_is_valid(r))
638 avahi_record_unref(r);
643 AvahiKey* avahi_dns_packet_consume_key(AvahiDnsPacket *p, int *ret_unicast_response) {
645 uint16_t type, class;
650 if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
651 avahi_dns_packet_consume_uint16(p, &type) < 0 ||
652 avahi_dns_packet_consume_uint16(p, &class) < 0)
655 if (ret_unicast_response)
656 *ret_unicast_response = !!(class & AVAHI_DNS_UNICAST_RESPONSE);
658 class &= ~AVAHI_DNS_UNICAST_RESPONSE;
660 if (!(k = avahi_key_new(name, class, type)))
663 if (!avahi_key_is_valid(k)) {
671 uint8_t* avahi_dns_packet_append_key(AvahiDnsPacket *p, AvahiKey *k, int unicast_response) {
680 if (!(t = avahi_dns_packet_append_name(p, k->name)) ||
681 !avahi_dns_packet_append_uint16(p, k->type) ||
682 !avahi_dns_packet_append_uint16(p, k->clazz | (unicast_response ? AVAHI_DNS_UNICAST_RESPONSE : 0))) {
690 static int append_rdata(AvahiDnsPacket *p, AvahiRecord *r) {
694 switch (r->key->type) {
696 case AVAHI_DNS_TYPE_PTR:
697 case AVAHI_DNS_TYPE_CNAME:
698 case AVAHI_DNS_TYPE_NS:
700 if (!(avahi_dns_packet_append_name(p, r->data.ptr.name)))
705 case AVAHI_DNS_TYPE_SRV:
707 if (!avahi_dns_packet_append_uint16(p, r->data.srv.priority) ||
708 !avahi_dns_packet_append_uint16(p, r->data.srv.weight) ||
709 !avahi_dns_packet_append_uint16(p, r->data.srv.port) ||
710 !avahi_dns_packet_append_name(p, r->data.srv.name))
715 case AVAHI_DNS_TYPE_HINFO:
716 if (!avahi_dns_packet_append_string(p, r->data.hinfo.cpu) ||
717 !avahi_dns_packet_append_string(p, r->data.hinfo.os))
722 case AVAHI_DNS_TYPE_TXT: {
727 n = avahi_string_list_serialize(r->data.txt.string_list, NULL, 0);
729 if (!(data = avahi_dns_packet_extend(p, n)))
732 avahi_string_list_serialize(r->data.txt.string_list, data, n);
737 case AVAHI_DNS_TYPE_A:
739 if (!avahi_dns_packet_append_bytes(p, &r->data.a.address, sizeof(r->data.a.address)))
744 case AVAHI_DNS_TYPE_AAAA:
746 if (!avahi_dns_packet_append_bytes(p, &r->data.aaaa.address, sizeof(r->data.aaaa.address)))
753 if (r->data.generic.size)
754 if (avahi_dns_packet_append_bytes(p, r->data.generic.data, r->data.generic.size))
764 uint8_t* avahi_dns_packet_append_record(AvahiDnsPacket *p, AvahiRecord *r, int cache_flush, unsigned max_ttl) {
765 uint8_t *t, *l, *start;
773 if (!(t = avahi_dns_packet_append_name(p, r->key->name)) ||
774 !avahi_dns_packet_append_uint16(p, r->key->type) ||
775 !avahi_dns_packet_append_uint16(p, cache_flush ? (r->key->clazz | AVAHI_DNS_CACHE_FLUSH) : (r->key->clazz &~ AVAHI_DNS_CACHE_FLUSH)) ||
776 !avahi_dns_packet_append_uint32(p, (max_ttl && r->ttl > max_ttl) ? max_ttl : r->ttl) ||
777 !(l = avahi_dns_packet_append_uint16(p, 0)))
780 start = avahi_dns_packet_extend(p, 0);
782 if (append_rdata(p, r) < 0)
785 size = avahi_dns_packet_extend(p, 0) - start;
786 assert(size <= 0xFFFF);
788 /* avahi_log_debug("appended %u", size); */
790 l[0] = (uint8_t) ((uint16_t) size >> 8);
791 l[1] = (uint8_t) ((uint16_t) size);
801 int avahi_dns_packet_is_empty(AvahiDnsPacket *p) {
804 return p->size <= AVAHI_DNS_PACKET_HEADER_SIZE;
807 size_t avahi_dns_packet_space(AvahiDnsPacket *p) {
810 assert(p->size <= p->max_size);
812 return p->max_size - p->size;
815 int avahi_rdata_parse(AvahiRecord *record, const void* rdata, size_t size) {
822 p.data = (void*) rdata;
823 p.max_size = p.size = size;
827 ret = parse_rdata(&p, record, size);
829 assert(!p.name_table);
834 size_t avahi_rdata_serialize(AvahiRecord *record, void *rdata, size_t max_size) {
840 assert(max_size > 0);
842 p.data = (void*) rdata;
843 p.max_size = max_size;
844 p.size = p.rindex = 0;
847 ret = append_rdata(&p, record);
850 avahi_hashmap_free(p.name_table);