DnsServer *manager_set_dns_server(Manager *m, DnsServer *s) {
assert(m);
if (m->current_dns_server == s)
return s;
if (s)
log_debug("Switching to %s DNS server %s.",
dns_server_type_to_string(s->type),
dns_server_string(s));
dns_server_unref(m->current_dns_server);
m->current_dns_server = dns_server_ref(s);
if (m->unicast_scope)
dns_cache_flush(&m->unicast_scope->cache);
return s;
}
void link_set_dnssec_mode(Link *l, DnssecMode mode) {
assert(l);
if (l->dnssec_mode == mode)
return;
if ((l->dnssec_mode == _DNSSEC_MODE_INVALID) ||
(l->dnssec_mode == DNSSEC_NO && mode != DNSSEC_NO) ||
(l->dnssec_mode == DNSSEC_ALLOW_DOWNGRADE && mode == DNSSEC_YES)) {
/* When switching from non-DNSSEC mode to DNSSEC mode, flush the cache. Also when switching from the
* allow-downgrade mode to full DNSSEC mode, flush it too. */
if (l->unicast_scope)
dns_cache_flush(&l->unicast_scope->cache);
}
l->dnssec_mode = mode;
}
DnsServer *manager_set_dns_server(Manager *m, DnsServer *s) {
assert(m);
if (m->current_dns_server == s)
return s;
if (s) {
_cleanup_free_ char *ip = NULL;
in_addr_to_string(s->family, &s->address, &ip);
log_info("Switching to system DNS server %s.", strna(ip));
}
dns_server_unref(m->current_dns_server);
m->current_dns_server = dns_server_ref(s);
if (m->unicast_scope)
dns_cache_flush(&m->unicast_scope->cache);
return s;
}
int manager_read_resolv_conf(Manager *m) {
_cleanup_fclose_ FILE *f = NULL;
struct stat st, own;
char line[LINE_MAX];
usec_t t;
int r;
assert(m);
/* Reads the system /etc/resolv.conf, if it exists and is not
* symlinked to our own resolv.conf instance */
if (!m->read_resolv_conf)
return 0;
r = stat("/etc/resolv.conf", &st);
if (r < 0) {
if (errno == ENOENT)
return 0;
r = log_warning_errno(errno, "Failed to stat /etc/resolv.conf: %m");
goto clear;
}
/* Have we already seen the file? */
t = timespec_load(&st.st_mtim);
if (t == m->resolv_conf_mtime)
return 0;
/* Is it symlinked to our own file? */
if (stat(PRIVATE_RESOLV_CONF, &own) >= 0 &&
st.st_dev == own.st_dev &&
st.st_ino == own.st_ino)
return 0;
f = fopen("/etc/resolv.conf", "re");
if (!f) {
if (errno == ENOENT)
return 0;
r = log_warning_errno(errno, "Failed to open /etc/resolv.conf: %m");
goto clear;
}
if (fstat(fileno(f), &st) < 0) {
r = log_error_errno(errno, "Failed to stat open file: %m");
goto clear;
}
dns_server_mark_all(m->dns_servers);
dns_search_domain_mark_all(m->search_domains);
FOREACH_LINE(line, f, r = -errno; goto clear) {
const char *a;
char *l;
l = strstrip(line);
if (IN_SET(*l, '#', ';'))
continue;
a = first_word(l, "nameserver");
if (a) {
r = manager_parse_dns_server_string_and_warn(m, DNS_SERVER_SYSTEM, a);
if (r < 0)
log_warning_errno(r, "Failed to parse DNS server address '%s', ignoring.", a);
continue;
}
a = first_word(l, "domain");
if (!a) /* We treat "domain" lines, and "search" lines as equivalent, and add both to our list. */
a = first_word(l, "search");
if (a) {
r = manager_parse_search_domains_and_warn(m, a);
if (r < 0)
log_warning_errno(r, "Failed to parse search domain string '%s', ignoring.", a);
}
}
m->resolv_conf_mtime = t;
/* Flush out all servers and search domains that are still
* marked. Those are then ones that didn't appear in the new
* /etc/resolv.conf */
dns_server_unlink_marked(m->dns_servers);
dns_search_domain_unlink_marked(m->search_domains);
/* Whenever /etc/resolv.conf changes, start using the first
* DNS server of it. This is useful to deal with broken
* network managing implementations (like NetworkManager),
* that when connecting to a VPN place both the VPN DNS
* servers and the local ones in /etc/resolv.conf. Without
* resetting the DNS server to use back to the first entry we
* will continue to use the local one thus being unable to
* resolve VPN domains. */
manager_set_dns_server(m, m->dns_servers);
/* Unconditionally flush the cache when /etc/resolv.conf is
* modified, even if the data it contained was completely
* identical to the previous version we used. We do this
* because altering /etc/resolv.conf is typically done when
* the network configuration changes, and that should be
* enough to flush the global unicast DNS cache. */
if (m->unicast_scope)
dns_cache_flush(&m->unicast_scope->cache);
/* If /etc/resolv.conf changed, make sure to forget everything we learned about the DNS servers. After all we
* might now talk to a very different DNS server that just happens to have the same IP address as an old one
* (think 192.168.1.1). */
dns_server_reset_features_all(m->dns_servers);
return 0;
clear:
dns_server_unlink_all(m->dns_servers);
dns_search_domain_unlink_all(m->search_domains);
return r;
}
