542 lines
14 KiB
C
542 lines
14 KiB
C
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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/***
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This file is part of systemd.
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Copyright 2014 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include "alloc-util.h"
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#include "dns-domain.h"
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#include "resolved-dns-answer.h"
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#include "string-util.h"
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DnsAnswer *dns_answer_new(unsigned n) {
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DnsAnswer *a;
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a = malloc0(offsetof(DnsAnswer, items) + sizeof(DnsAnswerItem) * n);
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if (!a)
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return NULL;
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a->n_ref = 1;
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a->n_allocated = n;
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return a;
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}
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DnsAnswer *dns_answer_ref(DnsAnswer *a) {
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if (!a)
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return NULL;
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assert(a->n_ref > 0);
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a->n_ref++;
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return a;
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}
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static void dns_answer_flush(DnsAnswer *a) {
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DnsResourceRecord *rr;
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if (!a)
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return;
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DNS_ANSWER_FOREACH(rr, a)
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dns_resource_record_unref(rr);
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a->n_rrs = 0;
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}
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DnsAnswer *dns_answer_unref(DnsAnswer *a) {
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if (!a)
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return NULL;
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assert(a->n_ref > 0);
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if (a->n_ref == 1) {
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dns_answer_flush(a);
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free(a);
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} else
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a->n_ref--;
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return NULL;
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}
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static int dns_answer_add_raw(DnsAnswer *a, DnsResourceRecord *rr, int ifindex) {
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assert(rr);
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if (!a)
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return -ENOSPC;
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if (a->n_rrs >= a->n_allocated)
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return -ENOSPC;
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a->items[a->n_rrs].rr = dns_resource_record_ref(rr);
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a->items[a->n_rrs].ifindex = ifindex;
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a->n_rrs++;
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return 1;
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}
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static int dns_answer_add_raw_all(DnsAnswer *a, DnsAnswer *source) {
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DnsResourceRecord *rr;
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int ifindex, r;
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DNS_ANSWER_FOREACH_IFINDEX(rr, ifindex, source) {
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r = dns_answer_add_raw(a, rr, ifindex);
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if (r < 0)
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return r;
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}
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return 0;
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}
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int dns_answer_add(DnsAnswer *a, DnsResourceRecord *rr, int ifindex) {
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unsigned i;
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int r;
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assert(rr);
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if (!a)
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return -ENOSPC;
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if (a->n_ref > 1)
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return -EBUSY;
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for (i = 0; i < a->n_rrs; i++) {
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if (a->items[i].ifindex != ifindex)
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continue;
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r = dns_resource_record_equal(a->items[i].rr, rr);
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if (r < 0)
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return r;
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if (r > 0) {
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/* Entry already exists, keep the entry with
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* the higher RR, or the one with TTL 0 */
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if (rr->ttl == 0 || (rr->ttl > a->items[i].rr->ttl && a->items[i].rr->ttl != 0)) {
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dns_resource_record_ref(rr);
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dns_resource_record_unref(a->items[i].rr);
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a->items[i].rr = rr;
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}
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return 0;
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}
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}
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return dns_answer_add_raw(a, rr, ifindex);
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}
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static int dns_answer_add_all(DnsAnswer *a, DnsAnswer *b) {
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DnsResourceRecord *rr;
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int ifindex, r;
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DNS_ANSWER_FOREACH_IFINDEX(rr, ifindex, b) {
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r = dns_answer_add(a, rr, ifindex);
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if (r < 0)
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return r;
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}
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return 0;
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}
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int dns_answer_add_extend(DnsAnswer **a, DnsResourceRecord *rr, int ifindex) {
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int r;
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assert(a);
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assert(rr);
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r = dns_answer_reserve_or_clone(a, 1);
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if (r < 0)
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return r;
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return dns_answer_add(*a, rr, ifindex);
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}
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int dns_answer_add_soa(DnsAnswer *a, const char *name, uint32_t ttl) {
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_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *soa = NULL;
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soa = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_SOA, name);
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if (!soa)
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return -ENOMEM;
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soa->ttl = ttl;
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soa->soa.mname = strdup(name);
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if (!soa->soa.mname)
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return -ENOMEM;
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soa->soa.rname = strappend("root.", name);
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if (!soa->soa.rname)
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return -ENOMEM;
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soa->soa.serial = 1;
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soa->soa.refresh = 1;
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soa->soa.retry = 1;
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soa->soa.expire = 1;
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soa->soa.minimum = ttl;
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return dns_answer_add(a, soa, 0);
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}
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int dns_answer_match_key(DnsAnswer *a, const DnsResourceKey *key) {
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DnsResourceRecord *i;
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int r;
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assert(key);
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if (!a)
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return 0;
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DNS_ANSWER_FOREACH(i, a) {
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r = dns_resource_key_match_rr(key, i, NULL);
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if (r < 0)
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return r;
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if (r > 0)
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return 1;
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}
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return 0;
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}
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int dns_answer_contains_rr(DnsAnswer *a, DnsResourceRecord *rr) {
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DnsResourceRecord *i;
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int r;
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assert(rr);
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DNS_ANSWER_FOREACH(i, a) {
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r = dns_resource_record_equal(i, rr);
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if (r < 0)
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return r;
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if (r > 0)
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return 1;
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}
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return 0;
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}
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int dns_answer_find_soa(DnsAnswer *a, const DnsResourceKey *key, DnsResourceRecord **ret) {
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DnsResourceRecord *rr;
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assert(key);
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assert(ret);
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if (!a)
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return 0;
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/* For a SOA record we can never find a matching SOA record */
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if (key->type == DNS_TYPE_SOA)
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return 0;
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DNS_ANSWER_FOREACH(rr, a) {
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if (dns_resource_key_match_soa(key, rr->key)) {
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*ret = rr;
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return 1;
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}
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}
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return 0;
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}
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int dns_answer_find_cname_or_dname(DnsAnswer *a, const DnsResourceKey *key, DnsResourceRecord **ret) {
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DnsResourceRecord *rr;
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assert(key);
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if (!a)
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return 0;
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/* For a {C,D}NAME record we can never find a matching {C,D}NAME record */
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if (key->type == DNS_TYPE_CNAME || key->type == DNS_TYPE_DNAME)
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return 0;
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DNS_ANSWER_FOREACH(rr, a) {
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if (dns_resource_key_match_cname_or_dname(key, rr->key, NULL)) {
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if (ret)
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*ret = rr;
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return 1;
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}
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}
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return 0;
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}
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int dns_answer_merge(DnsAnswer *a, DnsAnswer *b, DnsAnswer **ret) {
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_cleanup_(dns_answer_unrefp) DnsAnswer *k = NULL;
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int r;
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assert(ret);
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if (dns_answer_size(a) <= 0) {
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*ret = dns_answer_ref(b);
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return 0;
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}
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if (dns_answer_size(b) <= 0) {
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*ret = dns_answer_ref(a);
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return 0;
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}
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k = dns_answer_new(a->n_rrs + b->n_rrs);
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if (!k)
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return -ENOMEM;
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r = dns_answer_add_raw_all(k, a);
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if (r < 0)
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return r;
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r = dns_answer_add_all(k, b);
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if (r < 0)
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return r;
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*ret = k;
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k = NULL;
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return 0;
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}
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int dns_answer_extend(DnsAnswer **a, DnsAnswer *b) {
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DnsAnswer *merged;
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int r;
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assert(a);
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r = dns_answer_merge(*a, b, &merged);
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if (r < 0)
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return r;
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dns_answer_unref(*a);
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*a = merged;
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return 0;
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}
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int dns_answer_remove_by_key(DnsAnswer **a, const DnsResourceKey *key) {
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bool found = false, other = false;
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DnsResourceRecord *rr;
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unsigned i;
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int r;
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assert(a);
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assert(key);
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/* Remove all entries matching the specified key from *a */
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DNS_ANSWER_FOREACH(rr, *a) {
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r = dns_resource_key_equal(rr->key, key);
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if (r < 0)
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return r;
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if (r > 0)
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found = true;
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else
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other = true;
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if (found && other)
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break;
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}
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if (!found)
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return 0;
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if (!other) {
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*a = dns_answer_unref(*a); /* Return NULL for the empty answer */
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return 1;
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}
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if ((*a)->n_ref > 1) {
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_cleanup_(dns_answer_unrefp) DnsAnswer *copy = NULL;
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int ifindex;
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copy = dns_answer_new((*a)->n_rrs);
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if (!copy)
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return -ENOMEM;
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DNS_ANSWER_FOREACH_IFINDEX(rr, ifindex, *a) {
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r = dns_resource_key_equal(rr->key, key);
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if (r < 0)
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return r;
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if (r > 0)
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continue;
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r = dns_answer_add_raw(copy, rr, ifindex);
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if (r < 0)
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return r;
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}
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dns_answer_unref(*a);
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*a = copy;
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copy = NULL;
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return 1;
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}
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/* Only a single reference, edit in-place */
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i = 0;
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for (;;) {
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if (i >= (*a)->n_rrs)
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break;
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r = dns_resource_key_equal((*a)->items[i].rr->key, key);
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if (r < 0)
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return r;
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if (r > 0) {
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/* Kill this entry */
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dns_resource_record_unref((*a)->items[i].rr);
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memmove((*a)->items + i, (*a)->items + i + 1, sizeof(DnsAnswerItem) * ((*a)->n_rrs - i - 1));
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(*a)->n_rrs --;
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continue;
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} else
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/* Keep this entry */
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i++;
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}
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return 1;
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}
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int dns_answer_copy_by_key(DnsAnswer **a, DnsAnswer *source, const DnsResourceKey *key) {
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DnsResourceRecord *rr_source;
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int ifindex_source, r;
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assert(a);
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assert(key);
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/* Copy all RRs matching the specified key from source into *a */
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DNS_ANSWER_FOREACH_IFINDEX(rr_source, ifindex_source, source) {
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r = dns_resource_key_equal(rr_source->key, key);
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if (r < 0)
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return r;
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if (r == 0)
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continue;
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/* Make space for at least one entry */
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r = dns_answer_reserve_or_clone(a, 1);
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if (r < 0)
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return r;
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r = dns_answer_add(*a, rr_source, ifindex_source);
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if (r < 0)
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return r;
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}
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return 0;
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}
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void dns_answer_order_by_scope(DnsAnswer *a, bool prefer_link_local) {
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DnsAnswerItem *items;
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unsigned i, start, end;
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if (!a)
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return;
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if (a->n_rrs <= 1)
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return;
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start = 0;
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end = a->n_rrs-1;
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/* RFC 4795, Section 2.6 suggests we should order entries
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* depending on whether the sender is a link-local address. */
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items = newa(DnsAnswerItem, a->n_rrs);
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for (i = 0; i < a->n_rrs; i++) {
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if (a->items[i].rr->key->class == DNS_CLASS_IN &&
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((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) ||
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(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)))
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/* Order address records that are are not preferred to the end of the array */
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items[end--] = a->items[i];
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else
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/* Order all other records to the beginning of the array */
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items[start++] = a->items[i];
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}
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assert(start == end+1);
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memcpy(a->items, items, sizeof(DnsAnswerItem) * a->n_rrs);
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}
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int dns_answer_reserve(DnsAnswer **a, unsigned n_free) {
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DnsAnswer *n;
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assert(a);
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if (n_free <= 0)
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return 0;
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if (*a) {
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unsigned ns;
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if ((*a)->n_ref > 1)
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return -EBUSY;
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ns = (*a)->n_rrs + n_free;
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if ((*a)->n_allocated >= ns)
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return 0;
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/* Allocate more than we need */
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ns *= 2;
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n = realloc(*a, offsetof(DnsAnswer, items) + sizeof(DnsAnswerItem) * ns);
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if (!n)
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return -ENOMEM;
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n->n_allocated = ns;
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} else {
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n = dns_answer_new(n_free);
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if (!n)
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return -ENOMEM;
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}
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*a = n;
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return 0;
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}
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int dns_answer_reserve_or_clone(DnsAnswer **a, unsigned n_free) {
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_cleanup_(dns_answer_unrefp) DnsAnswer *n = NULL;
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int r;
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assert(a);
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/* Tries to extend the DnsAnswer object. And if that's not
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* possibly, since we are not the sole owner, then allocate a
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* new, appropriately sized one. Either way, after this call
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* the object will only have a single reference, and has room
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* for at least the specified number of RRs. */
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r = dns_answer_reserve(a, n_free);
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if (r != -EBUSY)
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return r;
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assert(*a);
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n = dns_answer_new(((*a)->n_rrs + n_free) * 2);
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if (!n)
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return -ENOMEM;
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r = dns_answer_add_raw_all(n, *a);
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if (r < 0)
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return r;
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dns_answer_unref(*a);
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*a = n;
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n = NULL;
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return 0;
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}
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