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>
33 #include <avahi-common/domain.h>
34 #include <avahi-common/malloc.h>
39 AvahiDnsPacket* avahi_dns_packet_new(unsigned mtu) {
44 max_size = AVAHI_DNS_PACKET_SIZE_MAX;
45 else if (mtu >= AVAHI_DNS_PACKET_EXTRA_SIZE)
46 max_size = mtu - AVAHI_DNS_PACKET_EXTRA_SIZE;
50 if (max_size < AVAHI_DNS_PACKET_HEADER_SIZE)
51 max_size = AVAHI_DNS_PACKET_HEADER_SIZE;
53 if (!(p = avahi_malloc(sizeof(AvahiDnsPacket) + max_size)))
56 p->size = p->rindex = AVAHI_DNS_PACKET_HEADER_SIZE;
57 p->max_size = max_size;
61 memset(AVAHI_DNS_PACKET_DATA(p), 0, p->size);
65 AvahiDnsPacket* avahi_dns_packet_new_query(unsigned mtu) {
68 if (!(p = avahi_dns_packet_new(mtu)))
71 avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_FLAGS, AVAHI_DNS_FLAGS(0, 0, 0, 0, 0, 0, 0, 0, 0, 0));
75 AvahiDnsPacket* avahi_dns_packet_new_response(unsigned mtu, int aa) {
78 if (!(p = avahi_dns_packet_new(mtu)))
81 avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_FLAGS, AVAHI_DNS_FLAGS(1, 0, aa, 0, 0, 0, 0, 0, 0, 0));
85 AvahiDnsPacket* avahi_dns_packet_new_reply(AvahiDnsPacket* p, unsigned mtu, int copy_queries, int aa) {
89 if (!(r = avahi_dns_packet_new_response(mtu, aa)))
93 unsigned saved_rindex;
96 saved_rindex = p->rindex;
97 p->rindex = AVAHI_DNS_PACKET_HEADER_SIZE;
99 for (n = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_QDCOUNT); n > 0; n--) {
101 int unicast_response;
103 if ((k = avahi_dns_packet_consume_key(p, &unicast_response))) {
104 avahi_dns_packet_append_key(r, k, unicast_response);
109 p->rindex = saved_rindex;
111 avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_QDCOUNT, avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_QDCOUNT));
114 avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_ID, avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_ID));
116 avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_FLAGS,
117 (avahi_dns_packet_get_field(r, AVAHI_DNS_FIELD_FLAGS) & ~AVAHI_DNS_FLAG_OPCODE) |
118 (avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) & AVAHI_DNS_FLAG_OPCODE));
124 void avahi_dns_packet_free(AvahiDnsPacket *p) {
128 avahi_hashmap_free(p->name_table);
133 void avahi_dns_packet_set_field(AvahiDnsPacket *p, unsigned idx, uint16_t v) {
135 assert(idx < AVAHI_DNS_PACKET_HEADER_SIZE);
137 ((uint16_t*) AVAHI_DNS_PACKET_DATA(p))[idx] = htons(v);
140 uint16_t avahi_dns_packet_get_field(AvahiDnsPacket *p, unsigned idx) {
142 assert(idx < AVAHI_DNS_PACKET_HEADER_SIZE);
144 return ntohs(((uint16_t*) AVAHI_DNS_PACKET_DATA(p))[idx]);
147 void avahi_dns_packet_inc_field(AvahiDnsPacket *p, unsigned idx) {
149 assert(idx < AVAHI_DNS_PACKET_HEADER_SIZE);
151 avahi_dns_packet_set_field(p, idx, avahi_dns_packet_get_field(p, idx) + 1);
154 uint8_t* avahi_dns_packet_append_name(AvahiDnsPacket *p, const char *name) {
155 uint8_t *d, *saved_ptr = NULL;
161 saved_size = p->size;
162 saved_ptr = avahi_dns_packet_extend(p, 0);
169 /* Check whether we can compress this name. */
171 if (p->name_table && (prev = avahi_hashmap_lookup(p->name_table, name))) {
174 assert(prev >= AVAHI_DNS_PACKET_DATA(p));
175 idx = (unsigned) (prev - AVAHI_DNS_PACKET_DATA(p));
177 assert(idx < p->size);
181 if (!(t = (uint8_t*) avahi_dns_packet_extend(p, sizeof(uint16_t))))
184 t[0] = (uint8_t) ((0xC000 | idx) >> 8);
185 t[1] = (uint8_t) idx;
192 if (!(avahi_unescape_label(&name, label, sizeof(label))))
195 if (!(d = avahi_dns_packet_append_string(p, label)))
199 /* This works only for normalized domain names */
200 p->name_table = avahi_hashmap_new(avahi_string_hash, avahi_string_equal, avahi_free, NULL);
202 if (!(u = avahi_strdup(pname)))
203 avahi_log_error("avahi_strdup() failed.");
205 avahi_hashmap_insert(p->name_table, u, d);
208 if (!(d = avahi_dns_packet_extend(p, 1)))
216 p->size = saved_size;
220 uint8_t* avahi_dns_packet_append_uint16(AvahiDnsPacket *p, uint16_t v) {
224 if (!(d = avahi_dns_packet_extend(p, sizeof(uint16_t))))
227 d[0] = (uint8_t) (v >> 8);
232 uint8_t *avahi_dns_packet_append_uint32(AvahiDnsPacket *p, uint32_t v) {
236 if (!(d = avahi_dns_packet_extend(p, sizeof(uint32_t))))
239 d[0] = (uint8_t) (v >> 24);
240 d[1] = (uint8_t) (v >> 16);
241 d[2] = (uint8_t) (v >> 8);
247 uint8_t *avahi_dns_packet_append_bytes(AvahiDnsPacket *p, const void *b, size_t l) {
254 if (!(d = avahi_dns_packet_extend(p, l)))
261 uint8_t* avahi_dns_packet_append_string(AvahiDnsPacket *p, const char *s) {
268 if ((k = strlen(s)) >= 255)
271 if (!(d = avahi_dns_packet_extend(p, k+1)))
280 uint8_t *avahi_dns_packet_extend(AvahiDnsPacket *p, size_t l) {
285 if (p->size+l > p->max_size)
288 d = AVAHI_DNS_PACKET_DATA(p) + p->size;
294 int avahi_dns_packet_check_valid(AvahiDnsPacket *p) {
298 if (p->size < AVAHI_DNS_PACKET_HEADER_SIZE)
301 flags = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS);
303 if (flags & AVAHI_DNS_FLAG_OPCODE)
309 int avahi_dns_packet_check_valid_multicast(AvahiDnsPacket *p) {
313 if (avahi_dns_packet_check_valid(p) < 0)
316 flags = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS);
318 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) {
335 assert(p && ret_name && l);
343 n = AVAHI_DNS_PACKET_DATA(p)[idx];
356 } else if (n <= 63) {
357 /* Uncompressed label */
362 if (idx + n > p->size)
365 if ((size_t) n + 1 > l)
374 if (!(avahi_escape_label((char*) AVAHI_DNS_PACKET_DATA(p) + idx, n, &ret_name, &l)))
381 } else if ((n & 0xC0) == 0xC0) {
382 /* Compressed label */
387 idx = ((unsigned) (AVAHI_DNS_PACKET_DATA(p)[idx] & ~0xC0)) << 8 | AVAHI_DNS_PACKET_DATA(p)[idx+1];
398 int avahi_dns_packet_consume_name(AvahiDnsPacket *p, char *ret_name, size_t l) {
401 if ((r = consume_labels(p, p->rindex, ret_name, l)) < 0)
408 int avahi_dns_packet_consume_uint16(AvahiDnsPacket *p, uint16_t *ret_v) {
414 if (p->rindex + sizeof(uint16_t) > p->size)
417 d = (uint8_t*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex);
418 *ret_v = (d[0] << 8) | d[1];
419 p->rindex += sizeof(uint16_t);
424 int avahi_dns_packet_consume_uint32(AvahiDnsPacket *p, uint32_t *ret_v) {
430 if (p->rindex + sizeof(uint32_t) > p->size)
433 d = (uint8_t*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex);
434 *ret_v = (d[0] << 24) | (d[1] << 16) | (d[2] << 8) | d[3];
435 p->rindex += sizeof(uint32_t);
440 int avahi_dns_packet_consume_bytes(AvahiDnsPacket *p, void * ret_data, size_t l) {
445 if (p->rindex + l > p->size)
448 memcpy(ret_data, AVAHI_DNS_PACKET_DATA(p) + p->rindex, l);
454 int avahi_dns_packet_consume_string(AvahiDnsPacket *p, char *ret_string, size_t l) {
461 if (p->rindex >= p->size)
464 k = AVAHI_DNS_PACKET_DATA(p)[p->rindex];
466 if (p->rindex+1+k > p->size)
472 memcpy(ret_string, AVAHI_DNS_PACKET_DATA(p)+p->rindex+1, l-1);
480 const void* avahi_dns_packet_get_rptr(AvahiDnsPacket *p) {
483 if (p->rindex > p->size)
486 return AVAHI_DNS_PACKET_DATA(p) + p->rindex;
489 int avahi_dns_packet_skip(AvahiDnsPacket *p, size_t length) {
492 if (p->rindex + length > p->size)
499 static int parse_rdata(AvahiDnsPacket *p, AvahiRecord *r, uint16_t rdlength) {
500 char buf[AVAHI_DOMAIN_NAME_MAX];
506 start = avahi_dns_packet_get_rptr(p);
508 switch (r->key->type) {
509 case AVAHI_DNS_TYPE_PTR:
510 case AVAHI_DNS_TYPE_CNAME:
511 case AVAHI_DNS_TYPE_NS:
513 if (avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
516 r->data.ptr.name = avahi_strdup(buf);
520 case AVAHI_DNS_TYPE_SRV:
522 if (avahi_dns_packet_consume_uint16(p, &r->data.srv.priority) < 0 ||
523 avahi_dns_packet_consume_uint16(p, &r->data.srv.weight) < 0 ||
524 avahi_dns_packet_consume_uint16(p, &r->data.srv.port) < 0 ||
525 avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
528 r->data.srv.name = avahi_strdup(buf);
531 case AVAHI_DNS_TYPE_HINFO:
533 if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
536 r->data.hinfo.cpu = avahi_strdup(buf);
538 if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
541 r->data.hinfo.os = avahi_strdup(buf);
544 case AVAHI_DNS_TYPE_TXT:
547 r->data.txt.string_list = avahi_string_list_parse(avahi_dns_packet_get_rptr(p), rdlength);
549 if (avahi_dns_packet_skip(p, rdlength) < 0)
552 r->data.txt.string_list = NULL;
556 case AVAHI_DNS_TYPE_A:
558 /* avahi_log_debug("A"); */
560 if (avahi_dns_packet_consume_bytes(p, &r->data.a.address, sizeof(AvahiIPv4Address)) < 0)
565 case AVAHI_DNS_TYPE_AAAA:
567 /* avahi_log_debug("aaaa"); */
569 if (avahi_dns_packet_consume_bytes(p, &r->data.aaaa.address, sizeof(AvahiIPv6Address)) < 0)
576 /* avahi_log_debug("generic"); */
580 r->data.generic.data = avahi_memdup(avahi_dns_packet_get_rptr(p), rdlength);
582 if (avahi_dns_packet_skip(p, rdlength) < 0)
589 /* Check if we read enough data */
590 if ((const uint8_t*) avahi_dns_packet_get_rptr(p) - (const uint8_t*) start != rdlength)
596 AvahiRecord* avahi_dns_packet_consume_record(AvahiDnsPacket *p, int *ret_cache_flush) {
597 char name[AVAHI_DOMAIN_NAME_MAX];
598 uint16_t type, class;
601 AvahiRecord *r = NULL;
605 if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
606 avahi_dns_packet_consume_uint16(p, &type) < 0 ||
607 avahi_dns_packet_consume_uint16(p, &class) < 0 ||
608 avahi_dns_packet_consume_uint32(p, &ttl) < 0 ||
609 avahi_dns_packet_consume_uint16(p, &rdlength) < 0 ||
610 p->rindex + rdlength > p->size)
614 *ret_cache_flush = !!(class & AVAHI_DNS_CACHE_FLUSH);
615 class &= ~AVAHI_DNS_CACHE_FLUSH;
617 if (!(r = avahi_record_new_full(name, class, type, ttl)))
620 if (parse_rdata(p, r, rdlength) < 0)
627 avahi_record_unref(r);
632 AvahiKey* avahi_dns_packet_consume_key(AvahiDnsPacket *p, int *ret_unicast_response) {
634 uint16_t type, class;
638 if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
639 avahi_dns_packet_consume_uint16(p, &type) < 0 ||
640 avahi_dns_packet_consume_uint16(p, &class) < 0)
643 if (ret_unicast_response)
644 *ret_unicast_response = !!(class & AVAHI_DNS_UNICAST_RESPONSE);
646 class &= ~AVAHI_DNS_UNICAST_RESPONSE;
648 return avahi_key_new(name, class, type);
651 uint8_t* avahi_dns_packet_append_key(AvahiDnsPacket *p, AvahiKey *k, int unicast_response) {
660 if (!(t = avahi_dns_packet_append_name(p, k->name)) ||
661 !avahi_dns_packet_append_uint16(p, k->type) ||
662 !avahi_dns_packet_append_uint16(p, k->clazz | (unicast_response ? AVAHI_DNS_UNICAST_RESPONSE : 0))) {
670 static int append_rdata(AvahiDnsPacket *p, AvahiRecord *r) {
674 switch (r->key->type) {
676 case AVAHI_DNS_TYPE_PTR:
677 case AVAHI_DNS_TYPE_CNAME:
678 case AVAHI_DNS_TYPE_NS:
680 if (!(avahi_dns_packet_append_name(p, r->data.ptr.name)))
685 case AVAHI_DNS_TYPE_SRV:
687 if (!avahi_dns_packet_append_uint16(p, r->data.srv.priority) ||
688 !avahi_dns_packet_append_uint16(p, r->data.srv.weight) ||
689 !avahi_dns_packet_append_uint16(p, r->data.srv.port) ||
690 !avahi_dns_packet_append_name(p, r->data.srv.name))
695 case AVAHI_DNS_TYPE_HINFO:
696 if (!avahi_dns_packet_append_string(p, r->data.hinfo.cpu) ||
697 !avahi_dns_packet_append_string(p, r->data.hinfo.os))
702 case AVAHI_DNS_TYPE_TXT: {
707 n = avahi_string_list_serialize(r->data.txt.string_list, NULL, 0);
709 if (!(data = avahi_dns_packet_extend(p, n)))
712 avahi_string_list_serialize(r->data.txt.string_list, data, n);
717 case AVAHI_DNS_TYPE_A:
719 if (!avahi_dns_packet_append_bytes(p, &r->data.a.address, sizeof(r->data.a.address)))
724 case AVAHI_DNS_TYPE_AAAA:
726 if (!avahi_dns_packet_append_bytes(p, &r->data.aaaa.address, sizeof(r->data.aaaa.address)))
733 if (r->data.generic.size)
734 if (avahi_dns_packet_append_bytes(p, r->data.generic.data, r->data.generic.size))
744 uint8_t* avahi_dns_packet_append_record(AvahiDnsPacket *p, AvahiRecord *r, int cache_flush, unsigned max_ttl) {
745 uint8_t *t, *l, *start;
753 if (!(t = avahi_dns_packet_append_name(p, r->key->name)) ||
754 !avahi_dns_packet_append_uint16(p, r->key->type) ||
755 !avahi_dns_packet_append_uint16(p, cache_flush ? (r->key->clazz | AVAHI_DNS_CACHE_FLUSH) : (r->key->clazz &~ AVAHI_DNS_CACHE_FLUSH)) ||
756 !avahi_dns_packet_append_uint32(p, (max_ttl && r->ttl > max_ttl) ? max_ttl : r->ttl) ||
757 !(l = avahi_dns_packet_append_uint16(p, 0)))
760 start = avahi_dns_packet_extend(p, 0);
762 if (append_rdata(p, r) < 0)
765 size = avahi_dns_packet_extend(p, 0) - start;
766 assert(size <= 0xFFFF);
768 /* avahi_log_debug("appended %u", size); */
770 l[0] = (uint8_t) ((uint16_t) size >> 8);
771 l[1] = (uint8_t) ((uint16_t) size);
781 int avahi_dns_packet_is_empty(AvahiDnsPacket *p) {
784 return p->size <= AVAHI_DNS_PACKET_HEADER_SIZE;
787 size_t avahi_dns_packet_space(AvahiDnsPacket *p) {
790 assert(p->size <= p->max_size);
792 return p->max_size - p->size;
795 int avahi_rdata_parse(AvahiRecord *record, const void* rdata, size_t size) {
802 p.data = (void*) rdata;
803 p.max_size = p.size = size;
807 ret = parse_rdata(&p, record, size);
809 assert(!p.name_table);
814 size_t avahi_rdata_serialize(AvahiRecord *record, void *rdata, size_t max_size) {
820 assert(max_size > 0);
822 p.data = (void*) rdata;
823 p.max_size = max_size;
824 p.size = p.rindex = 0;
827 ret = append_rdata(&p, record);
830 avahi_hashmap_free(p.name_table);