DnsServer *manager_get_dns_server(Manager *m) {
Link *l;
assert(m);
/* Try to read updates resolv.conf */
manager_read_resolv_conf(m);
/* If no DNS server was chosen so far, pick the first one */
if (!m->current_dns_server)
manager_set_dns_server(m, m->dns_servers);
if (!m->current_dns_server) {
bool found = false;
Iterator i;
/* No DNS servers configured, let's see if there are
* any on any links. If not, we use the fallback
* servers */
HASHMAP_FOREACH(l, m->links, i)
if (l->dns_servers) {
found = true;
break;
}
if (!found)
manager_set_dns_server(m, m->fallback_dns_servers);
}
int manager_write_resolv_conf(Manager *m) {
_cleanup_ordered_set_free_ OrderedSet *dns = NULL, *domains = NULL;
_cleanup_free_ char *temp_path = NULL;
_cleanup_fclose_ FILE *f = NULL;
int r;
assert(m);
/* Read the system /etc/resolv.conf first */
(void) manager_read_resolv_conf(m);
/* Add the full list to a set, to filter out duplicates */
r = manager_compile_dns_servers(m, &dns);
if (r < 0)
return log_warning_errno(r, "Failed to compile list of DNS servers: %m");
r = manager_compile_search_domains(m, &domains, false);
if (r < 0)
return log_warning_errno(r, "Failed to compile list of search domains: %m");
r = fopen_temporary_label(PRIVATE_RESOLV_CONF, PRIVATE_RESOLV_CONF, &f, &temp_path);
if (r < 0)
return log_warning_errno(r, "Failed to open private resolv.conf file for writing: %m");
(void) fchmod(fileno(f), 0644);
r = write_resolv_conf_contents(f, dns, domains);
if (r < 0) {
log_error_errno(r, "Failed to write private resolv.conf contents: %m");
goto fail;
}
if (rename(temp_path, PRIVATE_RESOLV_CONF) < 0) {
r = log_error_errno(errno, "Failed to move private resolv.conf file into place: %m");
goto fail;
}
return 0;
fail:
(void) unlink(PRIVATE_RESOLV_CONF);
(void) unlink(temp_path);
return r;
}
