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 <sys/types.h>
32 #include <netinet/in.h>
34 #include <avahi-common/defs.h>
35 #include <avahi-common/domain.h>
36 #include <avahi-common/malloc.h>
41 AvahiDnsPacket* avahi_dns_packet_new(unsigned mtu) {
46 max_size = AVAHI_DNS_PACKET_SIZE_MAX;
47 else if (mtu >= AVAHI_DNS_PACKET_EXTRA_SIZE)
48 max_size = mtu - AVAHI_DNS_PACKET_EXTRA_SIZE;
52 if (max_size < AVAHI_DNS_PACKET_HEADER_SIZE)
53 max_size = AVAHI_DNS_PACKET_HEADER_SIZE;
55 if (!(p = avahi_malloc(sizeof(AvahiDnsPacket) + max_size)))
58 p->size = p->rindex = AVAHI_DNS_PACKET_HEADER_SIZE;
59 p->max_size = max_size;
63 memset(AVAHI_DNS_PACKET_DATA(p), 0, p->size);
67 AvahiDnsPacket* avahi_dns_packet_new_query(unsigned mtu) {
70 if (!(p = avahi_dns_packet_new(mtu)))
73 avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_FLAGS, AVAHI_DNS_FLAGS(0, 0, 0, 0, 0, 0, 0, 0, 0, 0));
77 AvahiDnsPacket* avahi_dns_packet_new_response(unsigned mtu, int aa) {
80 if (!(p = avahi_dns_packet_new(mtu)))
83 avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_FLAGS, AVAHI_DNS_FLAGS(1, 0, aa, 0, 0, 0, 0, 0, 0, 0));
87 AvahiDnsPacket* avahi_dns_packet_new_reply(AvahiDnsPacket* p, unsigned mtu, int copy_queries, int aa) {
91 if (!(r = avahi_dns_packet_new_response(mtu, aa)))
95 unsigned saved_rindex;
98 saved_rindex = p->rindex;
99 p->rindex = AVAHI_DNS_PACKET_HEADER_SIZE;
101 for (n = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_QDCOUNT); n > 0; n--) {
103 int unicast_response;
105 if ((k = avahi_dns_packet_consume_key(p, &unicast_response))) {
106 avahi_dns_packet_append_key(r, k, unicast_response);
111 p->rindex = saved_rindex;
113 avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_QDCOUNT, avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_QDCOUNT));
116 avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_ID, avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_ID));
118 avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_FLAGS,
119 (avahi_dns_packet_get_field(r, AVAHI_DNS_FIELD_FLAGS) & ~AVAHI_DNS_FLAG_OPCODE) |
120 (avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) & AVAHI_DNS_FLAG_OPCODE));
126 void avahi_dns_packet_free(AvahiDnsPacket *p) {
130 avahi_hashmap_free(p->name_table);
135 void avahi_dns_packet_set_field(AvahiDnsPacket *p, unsigned idx, uint16_t v) {
137 assert(idx < AVAHI_DNS_PACKET_HEADER_SIZE);
139 ((uint16_t*) AVAHI_DNS_PACKET_DATA(p))[idx] = htons(v);
142 uint16_t avahi_dns_packet_get_field(AvahiDnsPacket *p, unsigned idx) {
144 assert(idx < AVAHI_DNS_PACKET_HEADER_SIZE);
146 return ntohs(((uint16_t*) AVAHI_DNS_PACKET_DATA(p))[idx]);
149 void avahi_dns_packet_inc_field(AvahiDnsPacket *p, unsigned idx) {
151 assert(idx < AVAHI_DNS_PACKET_HEADER_SIZE);
153 avahi_dns_packet_set_field(p, idx, avahi_dns_packet_get_field(p, idx) + 1);
156 uint8_t* avahi_dns_packet_append_name(AvahiDnsPacket *p, const char *name) {
157 uint8_t *d, *saved_ptr = NULL;
163 saved_size = p->size;
164 saved_ptr = avahi_dns_packet_extend(p, 0);
171 /* Check whether we can compress this name. */
173 if (p->name_table && (prev = avahi_hashmap_lookup(p->name_table, name))) {
176 assert(prev >= AVAHI_DNS_PACKET_DATA(p));
177 idx = (unsigned) (prev - AVAHI_DNS_PACKET_DATA(p));
179 assert(idx < p->size);
183 if (!(t = (uint8_t*) avahi_dns_packet_extend(p, sizeof(uint16_t))))
186 t[0] = (uint8_t) ((0xC000 | idx) >> 8);
187 t[1] = (uint8_t) idx;
194 if (!(avahi_unescape_label(&name, label, sizeof(label))))
197 if (!(d = avahi_dns_packet_append_string(p, label)))
201 /* This works only for normalized domain names */
202 p->name_table = avahi_hashmap_new(avahi_string_hash, avahi_string_equal, avahi_free, NULL);
204 if (!(u = avahi_strdup(pname)))
205 avahi_log_error("avahi_strdup() failed.");
207 avahi_hashmap_insert(p->name_table, u, d);
210 if (!(d = avahi_dns_packet_extend(p, 1)))
218 p->size = saved_size;
222 uint8_t* avahi_dns_packet_append_uint16(AvahiDnsPacket *p, uint16_t v) {
226 if (!(d = avahi_dns_packet_extend(p, sizeof(uint16_t))))
229 d[0] = (uint8_t) (v >> 8);
234 uint8_t *avahi_dns_packet_append_uint32(AvahiDnsPacket *p, uint32_t v) {
238 if (!(d = avahi_dns_packet_extend(p, sizeof(uint32_t))))
241 d[0] = (uint8_t) (v >> 24);
242 d[1] = (uint8_t) (v >> 16);
243 d[2] = (uint8_t) (v >> 8);
249 uint8_t *avahi_dns_packet_append_bytes(AvahiDnsPacket *p, const void *b, size_t l) {
256 if (!(d = avahi_dns_packet_extend(p, l)))
263 uint8_t* avahi_dns_packet_append_string(AvahiDnsPacket *p, const char *s) {
270 if ((k = strlen(s)) >= 255)
273 if (!(d = avahi_dns_packet_extend(p, k+1)))
282 uint8_t *avahi_dns_packet_extend(AvahiDnsPacket *p, size_t l) {
287 if (p->size+l > p->max_size)
290 d = AVAHI_DNS_PACKET_DATA(p) + p->size;
296 int avahi_dns_packet_check_valid(AvahiDnsPacket *p) {
300 if (p->size < AVAHI_DNS_PACKET_HEADER_SIZE)
303 flags = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS);
305 if (flags & AVAHI_DNS_FLAG_OPCODE)
311 int avahi_dns_packet_check_valid_multicast(AvahiDnsPacket *p) {
315 if (avahi_dns_packet_check_valid(p) < 0)
318 flags = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS);
320 if (flags & AVAHI_DNS_FLAG_RCODE)
326 int avahi_dns_packet_is_query(AvahiDnsPacket *p) {
329 return !(avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) & AVAHI_DNS_FLAG_QR);
332 static int consume_labels(AvahiDnsPacket *p, unsigned idx, char *ret_name, size_t l) {
338 assert(p && ret_name && l);
340 for (i = 0; i < AVAHI_DNS_LABELS_MAX; i++) {
346 n = AVAHI_DNS_PACKET_DATA(p)[idx];
359 } else if (n <= 63) {
360 /* Uncompressed label */
365 if (idx + n > p->size)
368 if ((size_t) n + 1 > l)
377 if (!(avahi_escape_label((char*) AVAHI_DNS_PACKET_DATA(p) + idx, n, &ret_name, &l)))
384 } else if ((n & 0xC0) == 0xC0) {
385 /* Compressed label */
390 label_ptr = ((unsigned) (AVAHI_DNS_PACKET_DATA(p)[idx] & ~0xC0)) << 8 | AVAHI_DNS_PACKET_DATA(p)[idx+1];
392 if ((label_ptr < AVAHI_DNS_PACKET_HEADER_SIZE) || (label_ptr >= idx))
408 int avahi_dns_packet_consume_name(AvahiDnsPacket *p, char *ret_name, size_t l) {
411 if ((r = consume_labels(p, p->rindex, ret_name, l)) < 0)
418 int avahi_dns_packet_consume_uint16(AvahiDnsPacket *p, uint16_t *ret_v) {
424 if (p->rindex + sizeof(uint16_t) > p->size)
427 d = (uint8_t*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex);
428 *ret_v = (d[0] << 8) | d[1];
429 p->rindex += sizeof(uint16_t);
434 int avahi_dns_packet_consume_uint32(AvahiDnsPacket *p, uint32_t *ret_v) {
440 if (p->rindex + sizeof(uint32_t) > p->size)
443 d = (uint8_t*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex);
444 *ret_v = (d[0] << 24) | (d[1] << 16) | (d[2] << 8) | d[3];
445 p->rindex += sizeof(uint32_t);
450 int avahi_dns_packet_consume_bytes(AvahiDnsPacket *p, void * ret_data, size_t l) {
455 if (p->rindex + l > p->size)
458 memcpy(ret_data, AVAHI_DNS_PACKET_DATA(p) + p->rindex, l);
464 int avahi_dns_packet_consume_string(AvahiDnsPacket *p, char *ret_string, size_t l) {
471 if (p->rindex >= p->size)
474 k = AVAHI_DNS_PACKET_DATA(p)[p->rindex];
476 if (p->rindex+1+k > p->size)
482 memcpy(ret_string, AVAHI_DNS_PACKET_DATA(p)+p->rindex+1, l-1);
490 const void* avahi_dns_packet_get_rptr(AvahiDnsPacket *p) {
493 if (p->rindex > p->size)
496 return AVAHI_DNS_PACKET_DATA(p) + p->rindex;
499 int avahi_dns_packet_skip(AvahiDnsPacket *p, size_t length) {
502 if (p->rindex + length > p->size)
509 static int parse_rdata(AvahiDnsPacket *p, AvahiRecord *r, uint16_t rdlength) {
510 char buf[AVAHI_DOMAIN_NAME_MAX];
516 start = avahi_dns_packet_get_rptr(p);
518 switch (r->key->type) {
519 case AVAHI_DNS_TYPE_PTR:
520 case AVAHI_DNS_TYPE_CNAME:
521 case AVAHI_DNS_TYPE_NS:
523 if (avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
526 r->data.ptr.name = avahi_strdup(buf);
530 case AVAHI_DNS_TYPE_SRV:
532 if (avahi_dns_packet_consume_uint16(p, &r->data.srv.priority) < 0 ||
533 avahi_dns_packet_consume_uint16(p, &r->data.srv.weight) < 0 ||
534 avahi_dns_packet_consume_uint16(p, &r->data.srv.port) < 0 ||
535 avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
538 r->data.srv.name = avahi_strdup(buf);
541 case AVAHI_DNS_TYPE_HINFO:
543 if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
546 r->data.hinfo.cpu = avahi_strdup(buf);
548 if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
551 r->data.hinfo.os = avahi_strdup(buf);
554 case AVAHI_DNS_TYPE_TXT:
557 if (avahi_string_list_parse(avahi_dns_packet_get_rptr(p), rdlength, &r->data.txt.string_list) < 0)
560 if (avahi_dns_packet_skip(p, rdlength) < 0)
563 r->data.txt.string_list = NULL;
567 case AVAHI_DNS_TYPE_A:
569 /* avahi_log_debug("A"); */
571 if (avahi_dns_packet_consume_bytes(p, &r->data.a.address, sizeof(AvahiIPv4Address)) < 0)
576 case AVAHI_DNS_TYPE_AAAA:
578 /* avahi_log_debug("aaaa"); */
580 if (avahi_dns_packet_consume_bytes(p, &r->data.aaaa.address, sizeof(AvahiIPv6Address)) < 0)
587 /* avahi_log_debug("generic"); */
591 r->data.generic.data = avahi_memdup(avahi_dns_packet_get_rptr(p), rdlength);
593 if (avahi_dns_packet_skip(p, rdlength) < 0)
600 /* Check if we read enough data */
601 if ((const uint8_t*) avahi_dns_packet_get_rptr(p) - (const uint8_t*) start != rdlength)
607 AvahiRecord* avahi_dns_packet_consume_record(AvahiDnsPacket *p, int *ret_cache_flush) {
608 char name[AVAHI_DOMAIN_NAME_MAX];
609 uint16_t type, class;
612 AvahiRecord *r = NULL;
616 if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
617 avahi_dns_packet_consume_uint16(p, &type) < 0 ||
618 avahi_dns_packet_consume_uint16(p, &class) < 0 ||
619 avahi_dns_packet_consume_uint32(p, &ttl) < 0 ||
620 avahi_dns_packet_consume_uint16(p, &rdlength) < 0 ||
621 p->rindex + rdlength > p->size)
625 *ret_cache_flush = !!(class & AVAHI_DNS_CACHE_FLUSH);
626 class &= ~AVAHI_DNS_CACHE_FLUSH;
628 if (!(r = avahi_record_new_full(name, class, type, ttl)))
631 if (parse_rdata(p, r, rdlength) < 0)
634 if (!avahi_record_is_valid(r))
641 avahi_record_unref(r);
646 AvahiKey* avahi_dns_packet_consume_key(AvahiDnsPacket *p, int *ret_unicast_response) {
648 uint16_t type, class;
653 if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
654 avahi_dns_packet_consume_uint16(p, &type) < 0 ||
655 avahi_dns_packet_consume_uint16(p, &class) < 0)
658 if (ret_unicast_response)
659 *ret_unicast_response = !!(class & AVAHI_DNS_UNICAST_RESPONSE);
661 class &= ~AVAHI_DNS_UNICAST_RESPONSE;
663 if (!(k = avahi_key_new(name, class, type)))
666 if (!avahi_key_is_valid(k)) {
674 uint8_t* avahi_dns_packet_append_key(AvahiDnsPacket *p, AvahiKey *k, int unicast_response) {
683 if (!(t = avahi_dns_packet_append_name(p, k->name)) ||
684 !avahi_dns_packet_append_uint16(p, k->type) ||
685 !avahi_dns_packet_append_uint16(p, k->clazz | (unicast_response ? AVAHI_DNS_UNICAST_RESPONSE : 0))) {
693 static int append_rdata(AvahiDnsPacket *p, AvahiRecord *r) {
697 switch (r->key->type) {
699 case AVAHI_DNS_TYPE_PTR:
700 case AVAHI_DNS_TYPE_CNAME:
701 case AVAHI_DNS_TYPE_NS:
703 if (!(avahi_dns_packet_append_name(p, r->data.ptr.name)))
708 case AVAHI_DNS_TYPE_SRV:
710 if (!avahi_dns_packet_append_uint16(p, r->data.srv.priority) ||
711 !avahi_dns_packet_append_uint16(p, r->data.srv.weight) ||
712 !avahi_dns_packet_append_uint16(p, r->data.srv.port) ||
713 !avahi_dns_packet_append_name(p, r->data.srv.name))
718 case AVAHI_DNS_TYPE_HINFO:
719 if (!avahi_dns_packet_append_string(p, r->data.hinfo.cpu) ||
720 !avahi_dns_packet_append_string(p, r->data.hinfo.os))
725 case AVAHI_DNS_TYPE_TXT: {
730 n = avahi_string_list_serialize(r->data.txt.string_list, NULL, 0);
732 if (!(data = avahi_dns_packet_extend(p, n)))
735 avahi_string_list_serialize(r->data.txt.string_list, data, n);
740 case AVAHI_DNS_TYPE_A:
742 if (!avahi_dns_packet_append_bytes(p, &r->data.a.address, sizeof(r->data.a.address)))
747 case AVAHI_DNS_TYPE_AAAA:
749 if (!avahi_dns_packet_append_bytes(p, &r->data.aaaa.address, sizeof(r->data.aaaa.address)))
756 if (r->data.generic.size)
757 if (avahi_dns_packet_append_bytes(p, r->data.generic.data, r->data.generic.size))
767 uint8_t* avahi_dns_packet_append_record(AvahiDnsPacket *p, AvahiRecord *r, int cache_flush, unsigned max_ttl) {
768 uint8_t *t, *l, *start;
776 if (!(t = avahi_dns_packet_append_name(p, r->key->name)) ||
777 !avahi_dns_packet_append_uint16(p, r->key->type) ||
778 !avahi_dns_packet_append_uint16(p, cache_flush ? (r->key->clazz | AVAHI_DNS_CACHE_FLUSH) : (r->key->clazz &~ AVAHI_DNS_CACHE_FLUSH)) ||
779 !avahi_dns_packet_append_uint32(p, (max_ttl && r->ttl > max_ttl) ? max_ttl : r->ttl) ||
780 !(l = avahi_dns_packet_append_uint16(p, 0)))
783 start = avahi_dns_packet_extend(p, 0);
785 if (append_rdata(p, r) < 0)
788 size = avahi_dns_packet_extend(p, 0) - start;
789 assert(size <= 0xFFFF);
791 /* avahi_log_debug("appended %u", size); */
793 l[0] = (uint8_t) ((uint16_t) size >> 8);
794 l[1] = (uint8_t) ((uint16_t) size);
804 int avahi_dns_packet_is_empty(AvahiDnsPacket *p) {
807 return p->size <= AVAHI_DNS_PACKET_HEADER_SIZE;
810 size_t avahi_dns_packet_space(AvahiDnsPacket *p) {
813 assert(p->size <= p->max_size);
815 return p->max_size - p->size;
818 int avahi_rdata_parse(AvahiRecord *record, const void* rdata, size_t size) {
825 p.data = (void*) rdata;
826 p.max_size = p.size = size;
830 ret = parse_rdata(&p, record, size);
832 assert(!p.name_table);
837 size_t avahi_rdata_serialize(AvahiRecord *record, void *rdata, size_t max_size) {
843 assert(max_size > 0);
845 p.data = (void*) rdata;
846 p.max_size = max_size;
847 p.size = p.rindex = 0;
850 ret = append_rdata(&p, record);
853 avahi_hashmap_free(p.name_table);