2014-07-16 00:26:02 +02:00
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/*-*- 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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2015-10-27 03:01:06 +01:00
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#include "alloc-util.h"
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2014-07-16 00:26:02 +02:00
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#include "resolved-dns-server.h"
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2015-11-24 17:03:12 +01:00
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#include "resolved-resolv-conf.h"
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2015-10-27 03:01:06 +01:00
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#include "siphash24.h"
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2015-11-24 17:03:12 +01:00
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#include "string-util.h"
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2014-07-16 00:26:02 +02:00
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2015-07-28 02:32:24 +02:00
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/* After how much time to repeat classic DNS requests */
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#define DNS_TIMEOUT_MIN_USEC (500 * USEC_PER_MSEC)
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#define DNS_TIMEOUT_MAX_USEC (5 * USEC_PER_SEC)
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2014-07-16 00:26:02 +02:00
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int dns_server_new(
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Manager *m,
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DnsServer **ret,
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2014-08-01 16:04:12 +02:00
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DnsServerType type,
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2014-07-16 00:26:02 +02:00
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Link *l,
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2014-07-18 16:09:30 +02:00
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int family,
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2014-07-18 13:59:49 +02:00
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const union in_addr_union *in_addr) {
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2014-07-16 00:26:02 +02:00
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DnsServer *s, *tail;
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assert(m);
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2014-08-01 16:04:12 +02:00
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assert((type == DNS_SERVER_LINK) == !!l);
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2014-07-16 00:26:02 +02:00
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assert(in_addr);
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s = new0(DnsServer, 1);
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if (!s)
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return -ENOMEM;
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2015-06-24 18:41:46 +02:00
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s->n_ref = 1;
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2014-08-01 16:04:12 +02:00
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s->type = type;
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2014-07-16 00:26:02 +02:00
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s->family = family;
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s->address = *in_addr;
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2015-07-28 02:32:24 +02:00
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s->resend_timeout = DNS_TIMEOUT_MIN_USEC;
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2014-07-16 00:26:02 +02:00
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2014-08-01 16:04:12 +02:00
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if (type == DNS_SERVER_LINK) {
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2014-07-23 23:10:00 +02:00
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LIST_FIND_TAIL(servers, l->dns_servers, tail);
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LIST_INSERT_AFTER(servers, l->dns_servers, tail, s);
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2014-07-16 00:26:02 +02:00
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s->link = l;
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2014-08-01 16:04:12 +02:00
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} else if (type == DNS_SERVER_SYSTEM) {
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2014-07-16 00:26:02 +02:00
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LIST_FIND_TAIL(servers, m->dns_servers, tail);
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LIST_INSERT_AFTER(servers, m->dns_servers, tail, s);
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2014-08-01 16:04:12 +02:00
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} else if (type == DNS_SERVER_FALLBACK) {
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LIST_FIND_TAIL(servers, m->fallback_dns_servers, tail);
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LIST_INSERT_AFTER(servers, m->fallback_dns_servers, tail, s);
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} else
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assert_not_reached("Unknown server type");
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2014-07-16 00:26:02 +02:00
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s->manager = m;
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2015-11-24 17:59:40 +01:00
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s->linked = true;
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2014-07-16 00:26:02 +02:00
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2014-08-01 16:04:12 +02:00
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/* A new DNS server that isn't fallback is added and the one
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* we used so far was a fallback one? Then let's try to pick
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* the new one */
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if (type != DNS_SERVER_FALLBACK &&
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2014-08-12 19:32:55 +02:00
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m->current_dns_server &&
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m->current_dns_server->type == DNS_SERVER_FALLBACK)
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manager_set_dns_server(m, NULL);
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2014-08-01 16:04:12 +02:00
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2014-07-16 00:26:02 +02:00
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if (ret)
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*ret = s;
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return 0;
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}
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2015-06-24 18:41:46 +02:00
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DnsServer* dns_server_ref(DnsServer *s) {
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2014-07-16 00:26:02 +02:00
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if (!s)
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return NULL;
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2015-06-24 18:41:46 +02:00
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assert(s->n_ref > 0);
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s->n_ref ++;
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2015-05-18 23:23:17 +02:00
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2015-06-24 18:41:46 +02:00
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return s;
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}
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2015-11-24 17:59:40 +01:00
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DnsServer* dns_server_unref(DnsServer *s) {
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2015-06-24 18:41:46 +02:00
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if (!s)
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return NULL;
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2014-08-12 19:32:55 +02:00
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2015-11-24 17:59:40 +01:00
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assert(s->n_ref > 0);
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s->n_ref --;
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2015-06-24 18:41:46 +02:00
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2015-11-24 17:59:40 +01:00
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if (s->n_ref > 0)
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return NULL;
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2014-07-16 00:26:02 +02:00
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free(s);
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return NULL;
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}
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2014-08-12 12:21:10 +02:00
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2015-11-24 17:59:40 +01:00
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void dns_server_unlink(DnsServer *s) {
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assert(s);
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assert(s->manager);
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2015-06-24 18:41:46 +02:00
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2015-11-24 17:59:40 +01:00
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/* This removes the specified server from the linked list of
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* servers, but any server might still stay around if it has
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* refs, for example from an ongoing transaction. */
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2015-06-24 18:41:46 +02:00
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2015-11-24 17:59:40 +01:00
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if (!s->linked)
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return;
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2015-06-24 18:41:46 +02:00
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2015-11-24 17:59:40 +01:00
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switch (s->type) {
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case DNS_SERVER_LINK:
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assert(s->link);
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LIST_REMOVE(servers, s->link->dns_servers, s);
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break;
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case DNS_SERVER_SYSTEM:
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LIST_REMOVE(servers, s->manager->dns_servers, s);
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break;
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case DNS_SERVER_FALLBACK:
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LIST_REMOVE(servers, s->manager->fallback_dns_servers, s);
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break;
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}
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s->linked = false;
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if (s->link && s->link->current_dns_server == s)
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link_set_dns_server(s->link, NULL);
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if (s->manager->current_dns_server == s)
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manager_set_dns_server(s->manager, NULL);
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dns_server_unref(s);
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2015-06-24 18:41:46 +02:00
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}
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2015-07-28 02:32:24 +02:00
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void dns_server_packet_received(DnsServer *s, usec_t rtt) {
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assert(s);
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2015-11-24 17:01:09 +01:00
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if (rtt <= s->max_rtt)
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return;
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s->max_rtt = rtt;
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s->resend_timeout = MIN(MAX(DNS_TIMEOUT_MIN_USEC, s->max_rtt * 2), DNS_TIMEOUT_MAX_USEC);
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2015-07-28 02:32:24 +02:00
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}
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void dns_server_packet_lost(DnsServer *s, usec_t usec) {
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assert(s);
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2015-11-24 17:01:09 +01:00
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if (s->resend_timeout > usec)
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return;
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s->resend_timeout = MIN(s->resend_timeout * 2, DNS_TIMEOUT_MAX_USEC);
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2015-07-28 02:32:24 +02:00
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}
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2015-10-04 00:22:41 +02:00
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static void dns_server_hash_func(const void *p, struct siphash *state) {
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2014-08-12 12:21:10 +02:00
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const DnsServer *s = p;
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2015-10-04 00:22:41 +02:00
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assert(s);
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2014-08-12 12:21:10 +02:00
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2015-10-04 00:22:41 +02:00
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siphash24_compress(&s->family, sizeof(s->family), state);
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siphash24_compress(&s->address, FAMILY_ADDRESS_SIZE(s->family), state);
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2014-08-12 12:21:10 +02:00
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}
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2014-08-13 01:00:18 +02:00
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static int dns_server_compare_func(const void *a, const void *b) {
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2014-08-12 12:21:10 +02:00
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const DnsServer *x = a, *y = b;
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if (x->family < y->family)
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return -1;
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if (x->family > y->family)
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return 1;
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return memcmp(&x->address, &y->address, FAMILY_ADDRESS_SIZE(x->family));
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}
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2014-08-13 01:00:18 +02:00
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const struct hash_ops dns_server_hash_ops = {
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.hash = dns_server_hash_func,
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.compare = dns_server_compare_func
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};
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2015-11-24 16:48:13 +01:00
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2015-11-24 17:59:40 +01:00
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DnsServer *manager_get_first_dns_server(Manager *m, DnsServerType t) {
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assert(m);
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switch (t) {
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case DNS_SERVER_SYSTEM:
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return m->dns_servers;
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case DNS_SERVER_FALLBACK:
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return m->fallback_dns_servers;
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2015-11-24 16:48:13 +01:00
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2015-11-24 17:59:40 +01:00
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default:
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return NULL;
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}
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}
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void manager_flush_dns_servers(Manager *m, DnsServerType type) {
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2015-11-24 16:48:13 +01:00
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assert(m);
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2015-11-24 17:59:40 +01:00
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for (;;) {
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DnsServer *first;
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2015-11-24 16:48:13 +01:00
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2015-11-24 17:59:40 +01:00
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first = manager_get_first_dns_server(m, type);
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if (!first)
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break;
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2015-11-24 16:48:13 +01:00
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2015-11-24 17:59:40 +01:00
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dns_server_unlink(first);
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2015-11-24 16:48:13 +01:00
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}
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}
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void manager_flush_marked_dns_servers(Manager *m, DnsServerType type) {
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2015-11-24 17:59:40 +01:00
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DnsServer *first, *s, *next;
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2015-11-24 16:48:13 +01:00
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assert(m);
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2015-11-24 17:59:40 +01:00
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first = manager_get_first_dns_server(m, type);
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2015-11-24 16:48:13 +01:00
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2015-11-24 17:59:40 +01:00
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LIST_FOREACH_SAFE(servers, s, next, first) {
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2015-11-24 16:48:13 +01:00
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if (!s->marked)
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continue;
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2015-11-24 17:59:40 +01:00
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dns_server_unlink(s);
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2015-11-24 16:48:13 +01:00
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}
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}
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void manager_mark_dns_servers(Manager *m, DnsServerType type) {
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DnsServer *first, *s;
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assert(m);
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2015-11-24 17:59:40 +01:00
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first = manager_get_first_dns_server(m, type);
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2015-11-24 16:48:13 +01:00
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LIST_FOREACH(servers, s, first)
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s->marked = true;
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}
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2015-11-24 17:03:12 +01:00
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2015-11-24 17:59:40 +01:00
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DnsServer* manager_find_dns_server(Manager *m, DnsServerType type, int family, const union in_addr_union *in_addr) {
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DnsServer *first, *s;
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2015-11-24 17:03:12 +01:00
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assert(m);
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assert(in_addr);
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2015-11-24 17:59:40 +01:00
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first = manager_get_first_dns_server(m, type);
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2015-11-24 17:03:12 +01:00
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2015-11-24 17:59:40 +01:00
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LIST_FOREACH(servers, s, first)
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2015-11-24 17:03:12 +01:00
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if (s->family == family && in_addr_equal(family, &s->address, in_addr) > 0)
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return s;
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return NULL;
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}
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DnsServer *manager_set_dns_server(Manager *m, DnsServer *s) {
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assert(m);
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if (m->current_dns_server == s)
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return s;
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if (s) {
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_cleanup_free_ char *ip = NULL;
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in_addr_to_string(s->family, &s->address, &ip);
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log_info("Switching to system DNS server %s.", strna(ip));
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}
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2015-11-24 17:59:40 +01:00
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dns_server_unref(m->current_dns_server);
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m->current_dns_server = dns_server_ref(s);
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2015-11-24 17:03:12 +01:00
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if (m->unicast_scope)
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dns_cache_flush(&m->unicast_scope->cache);
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return s;
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}
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DnsServer *manager_get_dns_server(Manager *m) {
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Link *l;
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assert(m);
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/* Try to read updates resolv.conf */
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manager_read_resolv_conf(m);
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/* If no DNS server was chose so far, pick the first one */
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if (!m->current_dns_server)
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manager_set_dns_server(m, m->dns_servers);
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if (!m->current_dns_server) {
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bool found = false;
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Iterator i;
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/* No DNS servers configured, let's see if there are
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* any on any links. If not, we use the fallback
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* servers */
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HASHMAP_FOREACH(l, m->links, i)
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if (l->dns_servers) {
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found = true;
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break;
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}
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if (!found)
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manager_set_dns_server(m, m->fallback_dns_servers);
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}
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return m->current_dns_server;
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}
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void manager_next_dns_server(Manager *m) {
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assert(m);
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/* If there's currently no DNS server set, then the next
|
|
|
|
* manager_get_dns_server() will find one */
|
|
|
|
if (!m->current_dns_server)
|
|
|
|
return;
|
|
|
|
|
2015-11-24 17:59:40 +01:00
|
|
|
/* Change to the next one, but make sure to follow the linked
|
|
|
|
* list only if the server is still linked. */
|
|
|
|
if (m->current_dns_server->linked && m->current_dns_server->servers_next) {
|
2015-11-24 17:03:12 +01:00
|
|
|
manager_set_dns_server(m, m->current_dns_server->servers_next);
|
|
|
|
return;
|
|
|
|
}
|
|
|
|
|
|
|
|
/* If there was no next one, then start from the beginning of
|
|
|
|
* the list */
|
|
|
|
if (m->current_dns_server->type == DNS_SERVER_FALLBACK)
|
|
|
|
manager_set_dns_server(m, m->fallback_dns_servers);
|
|
|
|
else
|
|
|
|
manager_set_dns_server(m, m->dns_servers);
|
|
|
|
}
|