resolved-dns-server.c revision 4b95f1798f22c1bb75295f448188560cb6ec9ece
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering This file is part of systemd.
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering Copyright 2014 Lennart Poettering
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering systemd is free software; you can redistribute it and/or modify it
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering under the terms of the GNU Lesser General Public License as published by
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering the Free Software Foundation; either version 2.1 of the License, or
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering (at your option) any later version.
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering systemd is distributed in the hope that it will be useful, but
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering WITHOUT ANY WARRANTY; without even the implied warranty of
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering Lesser General Public License for more details.
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering You should have received a copy of the GNU Lesser General Public License
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering along with systemd; If not, see <http://www.gnu.org/licenses/>.
9df3ba6c6cb65eecec06f39dfe85a3596cedac4eTom Gundersen/* After how much time to repeat classic DNS requests */
9df3ba6c6cb65eecec06f39dfe85a3596cedac4eTom Gundersen#define DNS_TIMEOUT_MIN_USEC (500 * USEC_PER_MSEC)
9df3ba6c6cb65eecec06f39dfe85a3596cedac4eTom Gundersen#define DNS_TIMEOUT_MAX_USEC (5 * USEC_PER_SEC)
4e945a6f7971fd7d1f6b2c62ee3afdaff3c95ce4Lennart Poettering assert((type == DNS_SERVER_LINK) == !!l);
6073b6f26ab9fc6bf335faa7073ec443eef093fdTom Gundersen LIST_FIND_TAIL(servers, l->dns_servers, tail);
6073b6f26ab9fc6bf335faa7073ec443eef093fdTom Gundersen LIST_INSERT_AFTER(servers, l->dns_servers, tail, s);
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering LIST_FIND_TAIL(servers, m->dns_servers, tail);
74b2466e14a1961bf3ac0e8a60cfaceec705bd59Lennart Poettering LIST_INSERT_AFTER(servers, m->dns_servers, tail, s);
4e945a6f7971fd7d1f6b2c62ee3afdaff3c95ce4Lennart Poettering LIST_FIND_TAIL(servers, m->fallback_dns_servers, tail);
4e945a6f7971fd7d1f6b2c62ee3afdaff3c95ce4Lennart Poettering LIST_INSERT_AFTER(servers, m->fallback_dns_servers, tail, s);
4e945a6f7971fd7d1f6b2c62ee3afdaff3c95ce4Lennart Poettering assert_not_reached("Unknown server type");
4e945a6f7971fd7d1f6b2c62ee3afdaff3c95ce4Lennart Poettering /* A new DNS server that isn't fallback is added and the one
4e945a6f7971fd7d1f6b2c62ee3afdaff3c95ce4Lennart Poettering * we used so far was a fallback one? Then let's try to pick
4e945a6f7971fd7d1f6b2c62ee3afdaff3c95ce4Lennart Poettering * the new one */
3e684349c2cead2e6fd2f816c34eb17daba23a49Lennart Poettering m->current_dns_server->type == DNS_SERVER_FALLBACK)
0eac462399c8e87bcce252cf058eba9f2678f2bdLennart PoetteringDnsServer* dns_server_unref(DnsServer *s) {
0eac462399c8e87bcce252cf058eba9f2678f2bdLennart Poettering /* This removes the specified server from the linked list of
0eac462399c8e87bcce252cf058eba9f2678f2bdLennart Poettering * servers, but any server might still stay around if it has
0eac462399c8e87bcce252cf058eba9f2678f2bdLennart Poettering * refs, for example from an ongoing transaction. */
0eac462399c8e87bcce252cf058eba9f2678f2bdLennart Poettering LIST_REMOVE(servers, s->link->dns_servers, s);
0eac462399c8e87bcce252cf058eba9f2678f2bdLennart Poettering LIST_REMOVE(servers, s->manager->dns_servers, s);
0eac462399c8e87bcce252cf058eba9f2678f2bdLennart Poettering LIST_REMOVE(servers, s->manager->fallback_dns_servers, s);
0eac462399c8e87bcce252cf058eba9f2678f2bdLennart Poettering if (s->link && s->link->current_dns_server == s)
0eac462399c8e87bcce252cf058eba9f2678f2bdLennart Poettering manager_set_dns_server(s->manager, NULL);
0b58db658b5c3f586ac3a837427f1f7fec2abb2eLennart Poetteringvoid dns_server_move_back_and_unmark(DnsServer *s) {
0b58db658b5c3f586ac3a837427f1f7fec2abb2eLennart Poettering /* Move us to the end of the list, so that the order is
0b58db658b5c3f586ac3a837427f1f7fec2abb2eLennart Poettering * strictly kept, if we are not at the end anyway. */
0b58db658b5c3f586ac3a837427f1f7fec2abb2eLennart Poettering LIST_REMOVE(servers, s->link->dns_servers, s);
0b58db658b5c3f586ac3a837427f1f7fec2abb2eLennart Poettering LIST_INSERT_AFTER(servers, s->link->dns_servers, tail, s);
0b58db658b5c3f586ac3a837427f1f7fec2abb2eLennart Poettering LIST_REMOVE(servers, s->manager->dns_servers, s);
0b58db658b5c3f586ac3a837427f1f7fec2abb2eLennart Poettering LIST_INSERT_AFTER(servers, s->manager->dns_servers, tail, s);
0b58db658b5c3f586ac3a837427f1f7fec2abb2eLennart Poettering LIST_REMOVE(servers, s->manager->fallback_dns_servers, s);
0b58db658b5c3f586ac3a837427f1f7fec2abb2eLennart Poettering LIST_INSERT_AFTER(servers, s->manager->fallback_dns_servers, tail, s);
0b58db658b5c3f586ac3a837427f1f7fec2abb2eLennart Poettering assert_not_reached("Unknown server type");
9df3ba6c6cb65eecec06f39dfe85a3596cedac4eTom Gundersenvoid dns_server_packet_received(DnsServer *s, usec_t rtt) {
84129d46cd6e95e142973da93aede4c7433c9600Lennart Poettering s->resend_timeout = MIN(MAX(DNS_TIMEOUT_MIN_USEC, s->max_rtt * 2), DNS_TIMEOUT_MAX_USEC);
9df3ba6c6cb65eecec06f39dfe85a3596cedac4eTom Gundersenvoid dns_server_packet_lost(DnsServer *s, usec_t usec) {
84129d46cd6e95e142973da93aede4c7433c9600Lennart Poettering s->resend_timeout = MIN(s->resend_timeout * 2, DNS_TIMEOUT_MAX_USEC);
b826ab586c9e0a9c0d438a75c28cf3a8ab485929Tom Gundersenstatic void dns_server_hash_func(const void *p, struct siphash *state) {
b826ab586c9e0a9c0d438a75c28cf3a8ab485929Tom Gundersen siphash24_compress(&s->family, sizeof(s->family), state);
b826ab586c9e0a9c0d438a75c28cf3a8ab485929Tom Gundersen siphash24_compress(&s->address, FAMILY_ADDRESS_SIZE(s->family), state);
d5099efc47d4e6ac60816b5381a5f607ab03f06eMichal Schmidtstatic int dns_server_compare_func(const void *a, const void *b) {
87f5a19343acf8ba697acc5a62bdb1a2b8c9eda3Lennart Poettering const DnsServer *x = a, *y = b;
87f5a19343acf8ba697acc5a62bdb1a2b8c9eda3Lennart Poettering return memcmp(&x->address, &y->address, FAMILY_ADDRESS_SIZE(x->family));
4b95f1798f22c1bb75295f448188560cb6ec9eceLennart Poetteringvoid dns_server_unlink_all(DnsServer *first) {
4b95f1798f22c1bb75295f448188560cb6ec9eceLennart Poetteringvoid dns_server_unlink_marked(DnsServer *first) {
4b95f1798f22c1bb75295f448188560cb6ec9eceLennart Poetteringvoid dns_server_mark_all(DnsServer *first) {
4b95f1798f22c1bb75295f448188560cb6ec9eceLennart Poettering dns_server_mark_all(first->servers_next);
4b95f1798f22c1bb75295f448188560cb6ec9eceLennart PoetteringDnsServer *dns_server_find(DnsServer *first, int family, const union in_addr_union *in_addr) {
4b95f1798f22c1bb75295f448188560cb6ec9eceLennart Poettering if (s->family == family && in_addr_equal(family, &s->address, in_addr) > 0)
4b95f1798f22c1bb75295f448188560cb6ec9eceLennart PoetteringDnsServer *manager_get_first_dns_server(Manager *m, DnsServerType t) {
f2f1dbe50fea13abadc9c1e845a29031b90b40f3Lennart PoetteringDnsServer *manager_set_dns_server(Manager *m, DnsServer *s) {
f2f1dbe50fea13abadc9c1e845a29031b90b40f3Lennart Poettering in_addr_to_string(s->family, &s->address, &ip);
f2f1dbe50fea13abadc9c1e845a29031b90b40f3Lennart Poettering log_info("Switching to system DNS server %s.", strna(ip));
0eac462399c8e87bcce252cf058eba9f2678f2bdLennart Poettering m->current_dns_server = dns_server_ref(s);
f2f1dbe50fea13abadc9c1e845a29031b90b40f3Lennart Poettering dns_cache_flush(&m->unicast_scope->cache);
f2f1dbe50fea13abadc9c1e845a29031b90b40f3Lennart PoetteringDnsServer *manager_get_dns_server(Manager *m) {
f2f1dbe50fea13abadc9c1e845a29031b90b40f3Lennart Poettering /* Try to read updates resolv.conf */
f2f1dbe50fea13abadc9c1e845a29031b90b40f3Lennart Poettering /* If no DNS server was chose so far, pick the first one */
f2f1dbe50fea13abadc9c1e845a29031b90b40f3Lennart Poettering manager_set_dns_server(m, m->dns_servers);
f2f1dbe50fea13abadc9c1e845a29031b90b40f3Lennart Poettering /* No DNS servers configured, let's see if there are
f2f1dbe50fea13abadc9c1e845a29031b90b40f3Lennart Poettering * any on any links. If not, we use the fallback
f2f1dbe50fea13abadc9c1e845a29031b90b40f3Lennart Poettering manager_set_dns_server(m, m->fallback_dns_servers);
f2f1dbe50fea13abadc9c1e845a29031b90b40f3Lennart Poetteringvoid manager_next_dns_server(Manager *m) {
f2f1dbe50fea13abadc9c1e845a29031b90b40f3Lennart Poettering /* If there's currently no DNS server set, then the next
f2f1dbe50fea13abadc9c1e845a29031b90b40f3Lennart Poettering * manager_get_dns_server() will find one */
0eac462399c8e87bcce252cf058eba9f2678f2bdLennart Poettering /* Change to the next one, but make sure to follow the linked
0eac462399c8e87bcce252cf058eba9f2678f2bdLennart Poettering * list only if the server is still linked. */
0eac462399c8e87bcce252cf058eba9f2678f2bdLennart Poettering if (m->current_dns_server->linked && m->current_dns_server->servers_next) {
f2f1dbe50fea13abadc9c1e845a29031b90b40f3Lennart Poettering manager_set_dns_server(m, m->current_dns_server->servers_next);
f2f1dbe50fea13abadc9c1e845a29031b90b40f3Lennart Poettering /* If there was no next one, then start from the beginning of
f2f1dbe50fea13abadc9c1e845a29031b90b40f3Lennart Poettering if (m->current_dns_server->type == DNS_SERVER_FALLBACK)
f2f1dbe50fea13abadc9c1e845a29031b90b40f3Lennart Poettering manager_set_dns_server(m, m->fallback_dns_servers);