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/*-*- 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 "siphash24.h"
#include "resolved-dns-server.h"
/* After how much time to repeat classic DNS requests */
#define DNS_TIMEOUT_MIN_USEC (500 * USEC_PER_MSEC)
#define DNS_TIMEOUT_MAX_USEC (5 * USEC_PER_SEC)
int dns_server_new(
Manager *m,
DnsServer **ret,
DnsServerType type,
Link *l,
int family,
const union in_addr_union *in_addr) {
DnsServer *s, *tail;
assert(m);
assert((type == DNS_SERVER_LINK) == !!l);
assert(in_addr);
s = new0(DnsServer, 1);
if (!s)
return -ENOMEM;
s->n_ref = 1;
s->type = type;
s->family = family;
s->address = *in_addr;
s->resend_timeout = DNS_TIMEOUT_MIN_USEC;
if (type == DNS_SERVER_LINK) {
LIST_FIND_TAIL(servers, l->dns_servers, tail);
LIST_INSERT_AFTER(servers, l->dns_servers, tail, s);
s->link = l;
} else if (type == DNS_SERVER_SYSTEM) {
LIST_FIND_TAIL(servers, m->dns_servers, tail);
LIST_INSERT_AFTER(servers, m->dns_servers, tail, s);
} else if (type == DNS_SERVER_FALLBACK) {
LIST_FIND_TAIL(servers, m->fallback_dns_servers, tail);
LIST_INSERT_AFTER(servers, m->fallback_dns_servers, tail, s);
} else
assert_not_reached("Unknown server type");
s->manager = m;
/* A new DNS server that isn't fallback is added and the one
* we used so far was a fallback one? Then let's try to pick
* the new one */
if (type != DNS_SERVER_FALLBACK &&
m->current_dns_server &&
m->current_dns_server->type == DNS_SERVER_FALLBACK)
manager_set_dns_server(m, NULL);
if (ret)
*ret = s;
return 0;
}
DnsServer* dns_server_ref(DnsServer *s) {
if (!s)
return NULL;
assert(s->n_ref > 0);
s->n_ref ++;
return s;
}
static DnsServer* dns_server_free(DnsServer *s) {
if (!s)
return NULL;
if (s->link && s->link->current_dns_server == s)
link_set_dns_server(s->link, NULL);
if (s->manager && s->manager->current_dns_server == s)
manager_set_dns_server(s->manager, NULL);
free(s);
return NULL;
}
DnsServer* dns_server_unref(DnsServer *s) {
if (!s)
return NULL;
assert(s->n_ref > 0);
if (s->n_ref == 1)
dns_server_free(s);
else
s->n_ref --;
return NULL;
}
void dns_server_packet_received(DnsServer *s, usec_t rtt) {
assert(s);
if (rtt > s->max_rtt) {
s->max_rtt = rtt;
s->resend_timeout = MIN(MAX(DNS_TIMEOUT_MIN_USEC, s->max_rtt * 2),
DNS_TIMEOUT_MAX_USEC);
}
}
void dns_server_packet_lost(DnsServer *s, usec_t usec) {
assert(s);
if (s->resend_timeout <= usec)
s->resend_timeout = MIN(s->resend_timeout * 2, DNS_TIMEOUT_MAX_USEC);
}
static void dns_server_hash_func(const void *p, struct siphash *state) {
const DnsServer *s = p;
assert(s);
siphash24_compress(&s->family, sizeof(s->family), state);
siphash24_compress(&s->address, FAMILY_ADDRESS_SIZE(s->family), state);
}
static int dns_server_compare_func(const void *a, const void *b) {
const DnsServer *x = a, *y = b;
if (x->family < y->family)
return -1;
if (x->family > y->family)
return 1;
return memcmp(&x->address, &y->address, FAMILY_ADDRESS_SIZE(x->family));
}
const struct hash_ops dns_server_hash_ops = {
.hash = dns_server_hash_func,
.compare = dns_server_compare_func
};
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