src/resolve/resolved-dns-answer.c

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2014 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include "resolved-dns-answer.h"
  23 #include "resolved-dns-domain.h"
  24
  25 DnsAnswer *dns_answer_new(unsigned n) {
  26         DnsAnswer *a;
  27
  28         assert(n > 0);
  29
  30         a = malloc0(offsetof(DnsAnswer, rrs) + sizeof(DnsResourceRecord*) * n);
  31         if (!a)
  32                 return NULL;
  33
  34         a->n_ref = 1;
  35         a->n_allocated = n;
  36
  37         return a;
  38 }
  39
  40 DnsAnswer *dns_answer_ref(DnsAnswer *a) {
  41         if (!a)
  42                 return NULL;
  43
  44         assert(a->n_ref > 0);
  45         a->n_ref++;
  46         return a;
  47 }
  48
  49 DnsAnswer *dns_answer_unref(DnsAnswer *a) {
  50         if (!a)
  51                 return NULL;
  52
  53         assert(a->n_ref > 0);
  54
  55         if (a->n_ref == 1) {
  56                 unsigned i;
  57
  58                 for (i = 0; i < a->n_rrs; i++)
  59                         dns_resource_record_unref(a->rrs[i]);
  60
  61                 free(a);
  62         } else
  63                 a->n_ref--;
  64
  65         return NULL;
  66 }
  67
  68 int dns_answer_add(DnsAnswer *a, DnsResourceRecord *rr) {
  69         unsigned i;
  70         int r;
  71
  72         assert(a);
  73         assert(rr);
  74
  75         for (i = 0; i < a->n_rrs; i++) {
  76                 r = dns_resource_record_equal(a->rrs[i], rr);
  77                 if (r < 0)
  78                         return r;
  79                 if (r > 0) {
  80                         /* Entry already exists, keep the entry with
  81                          * the higher RR, or the one with TTL 0 */
  82
  83                         if (rr->ttl == 0 || (rr->ttl > a->rrs[i]->ttl && a->rrs[i]->ttl != 0)) {
  84                                 dns_resource_record_ref(rr);
  85                                 dns_resource_record_unref(a->rrs[i]);
  86                                 a->rrs[i] = rr;
  87                         }
  88
  89                         return 0;
  90                 }
  91         }
  92
  93         if (a->n_rrs >= a->n_allocated)
  94                 return -ENOSPC;
  95
  96         a->rrs[a->n_rrs++] = dns_resource_record_ref(rr);
  97         return 1;
  98 }
  99
 100 int dns_answer_contains(DnsAnswer *a, DnsResourceKey *key) {
 101         unsigned i;
 102         int r;
 103
 104         assert(a);
 105         assert(key);
 106
 107         for (i = 0; i < a->n_rrs; i++) {
 108                 r = dns_resource_key_match_rr(key, a->rrs[i]);
 109                 if (r < 0)
 110                         return r;
 111                 if (r > 0)
 112                         return 1;
 113         }
 114
 115         return 0;
 116 }
 117
 118 int dns_answer_find_soa(DnsAnswer *a, DnsResourceKey *key, DnsResourceRecord **ret) {
 119         unsigned i;
 120
 121         assert(a);
 122         assert(key);
 123         assert(ret);
 124
 125         for (i = 0; i < a->n_rrs; i++) {
 126
 127                 if (a->rrs[i]->key->class != DNS_CLASS_IN)
 128                         continue;
 129
 130                 if (a->rrs[i]->key->type != DNS_TYPE_SOA)
 131                         continue;
 132
 133                 if (dns_name_endswith(DNS_RESOURCE_KEY_NAME(key), DNS_RESOURCE_KEY_NAME(a->rrs[i]->key))) {
 134                         *ret = a->rrs[i];
 135                         return 1;
 136                 }
 137         }
 138
 139         return 0;
 140 }
 141
 142 DnsAnswer *dns_answer_merge(DnsAnswer *a, DnsAnswer *b) {
 143         _cleanup_(dns_answer_unrefp) DnsAnswer *ret = NULL;
 144         DnsAnswer *k;
 145         unsigned i;
 146         int r;
 147
 148         if (a && (!b || b->n_rrs <= 0))
 149                 return dns_answer_ref(a);
 150         if ((!a || a->n_rrs <= 0) && b)
 151                 return dns_answer_ref(b);
 152
 153         ret = dns_answer_new((a ? a->n_rrs : 0) + (b ? b->n_rrs : 0));
 154         if (!ret)
 155                 return NULL;
 156
 157         if (a) {
 158                 for (i = 0; i < a->n_rrs; i++) {
 159                         r = dns_answer_add(ret, a->rrs[i]);
 160                         if (r < 0)
 161                                 return NULL;
 162                 }
 163         }
 164
 165         if (b) {
 166                 for (i = 0; i < b->n_rrs; i++) {
 167                         r = dns_answer_add(ret, b->rrs[i]);
 168                         if (r < 0)
 169                                 return NULL;
 170                 }
 171         }
 172
 173         k = ret;
 174         ret = NULL;
 175
 176         return k;
 177 }