resolved-dns-answer.c revision 801ad6a6a9cd8fbd58b9f9c27f20dbb3c87d47dd
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2014 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include "alloc-util.h"
#include "dns-domain.h"
#include "resolved-dns-answer.h"
#include "string-util.h"
DnsAnswer *dns_answer_new(unsigned n) {
DnsAnswer *a;
a = malloc0(offsetof(DnsAnswer, items) + sizeof(DnsAnswerItem) * n);
if (!a)
return NULL;
a->n_ref = 1;
a->n_allocated = n;
return a;
}
DnsAnswer *dns_answer_ref(DnsAnswer *a) {
if (!a)
return NULL;
assert(a->n_ref > 0);
a->n_ref++;
return a;
}
DnsAnswer *dns_answer_unref(DnsAnswer *a) {
if (!a)
return NULL;
assert(a->n_ref > 0);
if (a->n_ref == 1) {
unsigned i;
for (i = 0; i < a->n_rrs; i++)
dns_resource_record_unref(a->items[i].rr);
free(a);
} else
a->n_ref--;
return NULL;
}
int dns_answer_add(DnsAnswer *a, DnsResourceRecord *rr, int ifindex) {
unsigned i;
int r;
assert(rr);
if (!a)
return -ENOSPC;
for (i = 0; i < a->n_rrs; i++) {
if (a->items[i].ifindex != ifindex)
continue;
r = dns_resource_record_equal(a->items[i].rr, rr);
if (r < 0)
return r;
if (r > 0) {
/* Entry already exists, keep the entry with
* the higher RR, or the one with TTL 0 */
if (rr->ttl == 0 || (rr->ttl > a->items[i].rr->ttl && a->items[i].rr->ttl != 0)) {
dns_resource_record_ref(rr);
dns_resource_record_unref(a->items[i].rr);
a->items[i].rr = rr;
}
return 0;
}
}
if (a->n_rrs >= a->n_allocated)
return -ENOSPC;
a->items[a->n_rrs].rr = dns_resource_record_ref(rr);
a->items[a->n_rrs].ifindex = ifindex;
a->n_rrs++;
return 1;
}
int dns_answer_add_soa(DnsAnswer *a, const char *name, uint32_t ttl) {
_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *soa = NULL;
soa = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_SOA, name);
if (!soa)
return -ENOMEM;
soa->ttl = ttl;
soa->soa.mname = strdup(name);
if (!soa->soa.mname)
return -ENOMEM;
soa->soa.rname = strappend("root.", name);
if (!soa->soa.rname)
return -ENOMEM;
soa->soa.serial = 1;
soa->soa.refresh = 1;
soa->soa.retry = 1;
soa->soa.expire = 1;
soa->soa.minimum = ttl;
return dns_answer_add(a, soa, 0);
}
int dns_answer_contains(DnsAnswer *a, DnsResourceKey *key) {
unsigned i;
int r;
assert(key);
if (!a)
return 0;
for (i = 0; i < a->n_rrs; i++) {
r = dns_resource_key_match_rr(key, a->items[i].rr, NULL);
if (r < 0)
return r;
if (r > 0)
return 1;
}
return 0;
}
int dns_answer_match_soa(DnsResourceKey *key, DnsResourceKey *soa) {
if (soa->class != DNS_CLASS_IN)
return 0;
if (soa->type != DNS_TYPE_SOA)
return 0;
if (!dns_name_endswith(DNS_RESOURCE_KEY_NAME(key), DNS_RESOURCE_KEY_NAME(soa)))
return 0;
return 1;
}
int dns_answer_find_soa(DnsAnswer *a, DnsResourceKey *key, DnsResourceRecord **ret) {
unsigned i;
assert(key);
assert(ret);
if (!a)
return 0;
/* For a SOA record we can never find a matching SOA record */
if (key->type == DNS_TYPE_SOA)
return 0;
for (i = 0; i < a->n_rrs; i++) {
if (dns_answer_match_soa(key, a->items[i].rr->key)) {
*ret = a->items[i].rr;
return 1;
}
}
return 0;
}
DnsAnswer *dns_answer_merge(DnsAnswer *a, DnsAnswer *b) {
_cleanup_(dns_answer_unrefp) DnsAnswer *ret = NULL;
DnsAnswer *k;
unsigned i;
int r;
if (a && (!b || b->n_rrs <= 0))
return dns_answer_ref(a);
if ((!a || a->n_rrs <= 0) && b)
return dns_answer_ref(b);
ret = dns_answer_new((a ? a->n_rrs : 0) + (b ? b->n_rrs : 0));
if (!ret)
return NULL;
if (a) {
for (i = 0; i < a->n_rrs; i++) {
r = dns_answer_add(ret, a->items[i].rr, a->items[i].ifindex);
if (r < 0)
return NULL;
}
}
if (b) {
for (i = 0; i < b->n_rrs; i++) {
r = dns_answer_add(ret, b->items[i].rr, b->items[i].ifindex);
if (r < 0)
return NULL;
}
}
k = ret;
ret = NULL;
return k;
}
void dns_answer_order_by_scope(DnsAnswer *a, bool prefer_link_local) {
DnsAnswerItem *items;
unsigned i, start, end;
if (!a)
return;
if (a->n_rrs <= 1)
return;
start = 0;
end = a->n_rrs-1;
/* RFC 4795, Section 2.6 suggests we should order entries
* depending on whether the sender is a link-local address. */
items = newa(DnsAnswerItem, a->n_rrs);
for (i = 0; i < a->n_rrs; i++) {
if (a->items[i].rr->key->class == DNS_CLASS_IN &&
((a->items[i].rr->key->type == DNS_TYPE_A && in_addr_is_link_local(AF_INET, (union in_addr_union*) &a->items[i].rr->a.in_addr) != prefer_link_local) ||
(a->items[i].rr->key->type == DNS_TYPE_AAAA && in_addr_is_link_local(AF_INET6, (union in_addr_union*) &a->items[i].rr->aaaa.in6_addr) != prefer_link_local)))
/* Order address records that are are not preferred to the end of the array */
items[end--] = a->items[i];
else
/* Order all other records to the beginning of the array */
items[start++] = a->items[i];
}
assert(start == end+1);
memcpy(a->items, items, sizeof(DnsAnswerItem) * a->n_rrs);
}
int dns_answer_reserve(DnsAnswer **a, unsigned n_free) {
DnsAnswer *n;
if (n_free <= 0)
return 0;
if (*a) {
unsigned ns;
if ((*a)->n_ref > 1)
return -EBUSY;
ns = (*a)->n_rrs + n_free;
if ((*a)->n_allocated >= ns)
return 0;
n = realloc(*a, offsetof(DnsAnswer, items) + sizeof(DnsAnswerItem) * ns);
if (!n)
return -ENOMEM;
n->n_allocated = ns;
} else {
n = dns_answer_new(n_free);
if (!n)
return -ENOMEM;
}
*a = n;
return 0;
}