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) {
336 assert(p && ret_name && l);
338 for (i = 0; i < 127; i++) {
344 n = AVAHI_DNS_PACKET_DATA(p)[idx];
357 } else if (n <= 63) {
358 /* Uncompressed label */
363 if (idx + n > p->size)
366 if ((size_t) n + 1 > l)
375 if (!(avahi_escape_label((char*) AVAHI_DNS_PACKET_DATA(p) + idx, n, &ret_name, &l)))
382 } else if ((n & 0xC0) == 0xC0) {
383 /* Compressed label */
388 idx = ((unsigned) (AVAHI_DNS_PACKET_DATA(p)[idx] & ~0xC0)) << 8 | AVAHI_DNS_PACKET_DATA(p)[idx+1];
399 int avahi_dns_packet_consume_name(AvahiDnsPacket *p, char *ret_name, size_t l) {
402 if ((r = consume_labels(p, p->rindex, ret_name, l)) < 0)
409 int avahi_dns_packet_consume_uint16(AvahiDnsPacket *p, uint16_t *ret_v) {
415 if (p->rindex + sizeof(uint16_t) > p->size)
418 d = (uint8_t*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex);
419 *ret_v = (d[0] << 8) | d[1];
420 p->rindex += sizeof(uint16_t);
425 int avahi_dns_packet_consume_uint32(AvahiDnsPacket *p, uint32_t *ret_v) {
431 if (p->rindex + sizeof(uint32_t) > p->size)
434 d = (uint8_t*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex);
435 *ret_v = (d[0] << 24) | (d[1] << 16) | (d[2] << 8) | d[3];
436 p->rindex += sizeof(uint32_t);
441 int avahi_dns_packet_consume_bytes(AvahiDnsPacket *p, void * ret_data, size_t l) {
446 if (p->rindex + l > p->size)
449 memcpy(ret_data, AVAHI_DNS_PACKET_DATA(p) + p->rindex, l);
455 int avahi_dns_packet_consume_string(AvahiDnsPacket *p, char *ret_string, size_t l) {
462 if (p->rindex >= p->size)
465 k = AVAHI_DNS_PACKET_DATA(p)[p->rindex];
467 if (p->rindex+1+k > p->size)
473 memcpy(ret_string, AVAHI_DNS_PACKET_DATA(p)+p->rindex+1, l-1);
481 const void* avahi_dns_packet_get_rptr(AvahiDnsPacket *p) {
484 if (p->rindex > p->size)
487 return AVAHI_DNS_PACKET_DATA(p) + p->rindex;
490 int avahi_dns_packet_skip(AvahiDnsPacket *p, size_t length) {
493 if (p->rindex + length > p->size)
500 static int parse_rdata(AvahiDnsPacket *p, AvahiRecord *r, uint16_t rdlength) {
501 char buf[AVAHI_DOMAIN_NAME_MAX];
507 start = avahi_dns_packet_get_rptr(p);
509 switch (r->key->type) {
510 case AVAHI_DNS_TYPE_PTR:
511 case AVAHI_DNS_TYPE_CNAME:
512 case AVAHI_DNS_TYPE_NS:
514 if (avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
517 r->data.ptr.name = avahi_strdup(buf);
521 case AVAHI_DNS_TYPE_SRV:
523 if (avahi_dns_packet_consume_uint16(p, &r->data.srv.priority) < 0 ||
524 avahi_dns_packet_consume_uint16(p, &r->data.srv.weight) < 0 ||
525 avahi_dns_packet_consume_uint16(p, &r->data.srv.port) < 0 ||
526 avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
529 r->data.srv.name = avahi_strdup(buf);
532 case AVAHI_DNS_TYPE_HINFO:
534 if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
537 r->data.hinfo.cpu = avahi_strdup(buf);
539 if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
542 r->data.hinfo.os = avahi_strdup(buf);
545 case AVAHI_DNS_TYPE_TXT:
548 if (avahi_string_list_parse(avahi_dns_packet_get_rptr(p), rdlength, &r->data.txt.string_list) < 0)
551 if (avahi_dns_packet_skip(p, rdlength) < 0)
554 r->data.txt.string_list = NULL;
558 case AVAHI_DNS_TYPE_A:
560 /* avahi_log_debug("A"); */
562 if (avahi_dns_packet_consume_bytes(p, &r->data.a.address, sizeof(AvahiIPv4Address)) < 0)
567 case AVAHI_DNS_TYPE_AAAA:
569 /* avahi_log_debug("aaaa"); */
571 if (avahi_dns_packet_consume_bytes(p, &r->data.aaaa.address, sizeof(AvahiIPv6Address)) < 0)
578 /* avahi_log_debug("generic"); */
582 r->data.generic.data = avahi_memdup(avahi_dns_packet_get_rptr(p), rdlength);
584 if (avahi_dns_packet_skip(p, rdlength) < 0)
591 /* Check if we read enough data */
592 if ((const uint8_t*) avahi_dns_packet_get_rptr(p) - (const uint8_t*) start != rdlength)
598 AvahiRecord* avahi_dns_packet_consume_record(AvahiDnsPacket *p, int *ret_cache_flush) {
599 char name[AVAHI_DOMAIN_NAME_MAX];
600 uint16_t type, class;
603 AvahiRecord *r = NULL;
607 if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
608 avahi_dns_packet_consume_uint16(p, &type) < 0 ||
609 avahi_dns_packet_consume_uint16(p, &class) < 0 ||
610 avahi_dns_packet_consume_uint32(p, &ttl) < 0 ||
611 avahi_dns_packet_consume_uint16(p, &rdlength) < 0 ||
612 p->rindex + rdlength > p->size)
616 *ret_cache_flush = !!(class & AVAHI_DNS_CACHE_FLUSH);
617 class &= ~AVAHI_DNS_CACHE_FLUSH;
619 if (!(r = avahi_record_new_full(name, class, type, ttl)))
622 if (parse_rdata(p, r, rdlength) < 0)
625 if (!avahi_record_is_valid(r))
632 avahi_record_unref(r);
637 AvahiKey* avahi_dns_packet_consume_key(AvahiDnsPacket *p, int *ret_unicast_response) {
639 uint16_t type, class;
644 if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
645 avahi_dns_packet_consume_uint16(p, &type) < 0 ||
646 avahi_dns_packet_consume_uint16(p, &class) < 0)
649 if (ret_unicast_response)
650 *ret_unicast_response = !!(class & AVAHI_DNS_UNICAST_RESPONSE);
652 class &= ~AVAHI_DNS_UNICAST_RESPONSE;
654 if (!(k = avahi_key_new(name, class, type)))
657 if (!avahi_key_is_valid(k)) {
665 uint8_t* avahi_dns_packet_append_key(AvahiDnsPacket *p, AvahiKey *k, int unicast_response) {
674 if (!(t = avahi_dns_packet_append_name(p, k->name)) ||
675 !avahi_dns_packet_append_uint16(p, k->type) ||
676 !avahi_dns_packet_append_uint16(p, k->clazz | (unicast_response ? AVAHI_DNS_UNICAST_RESPONSE : 0))) {
684 static int append_rdata(AvahiDnsPacket *p, AvahiRecord *r) {
688 switch (r->key->type) {
690 case AVAHI_DNS_TYPE_PTR:
691 case AVAHI_DNS_TYPE_CNAME:
692 case AVAHI_DNS_TYPE_NS:
694 if (!(avahi_dns_packet_append_name(p, r->data.ptr.name)))
699 case AVAHI_DNS_TYPE_SRV:
701 if (!avahi_dns_packet_append_uint16(p, r->data.srv.priority) ||
702 !avahi_dns_packet_append_uint16(p, r->data.srv.weight) ||
703 !avahi_dns_packet_append_uint16(p, r->data.srv.port) ||
704 !avahi_dns_packet_append_name(p, r->data.srv.name))
709 case AVAHI_DNS_TYPE_HINFO:
710 if (!avahi_dns_packet_append_string(p, r->data.hinfo.cpu) ||
711 !avahi_dns_packet_append_string(p, r->data.hinfo.os))
716 case AVAHI_DNS_TYPE_TXT: {
721 n = avahi_string_list_serialize(r->data.txt.string_list, NULL, 0);
723 if (!(data = avahi_dns_packet_extend(p, n)))
726 avahi_string_list_serialize(r->data.txt.string_list, data, n);
731 case AVAHI_DNS_TYPE_A:
733 if (!avahi_dns_packet_append_bytes(p, &r->data.a.address, sizeof(r->data.a.address)))
738 case AVAHI_DNS_TYPE_AAAA:
740 if (!avahi_dns_packet_append_bytes(p, &r->data.aaaa.address, sizeof(r->data.aaaa.address)))
747 if (r->data.generic.size)
748 if (avahi_dns_packet_append_bytes(p, r->data.generic.data, r->data.generic.size))
758 uint8_t* avahi_dns_packet_append_record(AvahiDnsPacket *p, AvahiRecord *r, int cache_flush, unsigned max_ttl) {
759 uint8_t *t, *l, *start;
767 if (!(t = avahi_dns_packet_append_name(p, r->key->name)) ||
768 !avahi_dns_packet_append_uint16(p, r->key->type) ||
769 !avahi_dns_packet_append_uint16(p, cache_flush ? (r->key->clazz | AVAHI_DNS_CACHE_FLUSH) : (r->key->clazz &~ AVAHI_DNS_CACHE_FLUSH)) ||
770 !avahi_dns_packet_append_uint32(p, (max_ttl && r->ttl > max_ttl) ? max_ttl : r->ttl) ||
771 !(l = avahi_dns_packet_append_uint16(p, 0)))
774 start = avahi_dns_packet_extend(p, 0);
776 if (append_rdata(p, r) < 0)
779 size = avahi_dns_packet_extend(p, 0) - start;
780 assert(size <= 0xFFFF);
782 /* avahi_log_debug("appended %u", size); */
784 l[0] = (uint8_t) ((uint16_t) size >> 8);
785 l[1] = (uint8_t) ((uint16_t) size);
795 int avahi_dns_packet_is_empty(AvahiDnsPacket *p) {
798 return p->size <= AVAHI_DNS_PACKET_HEADER_SIZE;
801 size_t avahi_dns_packet_space(AvahiDnsPacket *p) {
804 assert(p->size <= p->max_size);
806 return p->max_size - p->size;
809 int avahi_rdata_parse(AvahiRecord *record, const void* rdata, size_t size) {
816 p.data = (void*) rdata;
817 p.max_size = p.size = size;
821 ret = parse_rdata(&p, record, size);
823 assert(!p.name_table);
828 size_t avahi_rdata_serialize(AvahiRecord *record, void *rdata, size_t max_size) {
834 assert(max_size > 0);
836 p.data = (void*) rdata;
837 p.max_size = max_size;
838 p.size = p.rindex = 0;
841 ret = append_rdata(&p, record);
844 avahi_hashmap_free(p.name_table);