1 files changed, 94 insertions, 0 deletions
diff --git a/src/resolve/resolved-dns-server.c b/src/resolve/resolved-dns-server.c
index 8b88a3d690..207ec4c603 100644
--- a/src/resolve/resolved-dns-server.c
+++ b/src/resolve/resolved-dns-server.c
@@ -21,7 +21,9 @@
 
 #include "alloc-util.h"
 #include "resolved-dns-server.h"
+#include "resolved-resolv-conf.h"
 #include "siphash24.h"
+#include "string-util.h"
 
 /* After how much time to repeat classic DNS requests */
 #define DNS_TIMEOUT_MIN_USEC (500 * USEC_PER_MSEC)
@@ -205,3 +207,95 @@ void manager_mark_dns_servers(Manager *m, DnsServerType type) {
         LIST_FOREACH(servers, s, first)
                 s->marked = true;
 }
+
+DnsServer* manager_find_dns_server(Manager *m, int family, const union in_addr_union *in_addr) {
+        DnsServer *s;
+
+        assert(m);
+        assert(in_addr);
+
+        LIST_FOREACH(servers, s, m->dns_servers)
+                if (s->family == family && in_addr_equal(family, &s->address, in_addr) > 0)
+                        return s;
+
+        LIST_FOREACH(servers, s, m->fallback_dns_servers)
+                if (s->family == family && in_addr_equal(family, &s->address, in_addr) > 0)
+                        return s;
+
+        return NULL;
+}
+
+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));
+        }
+
+        m->current_dns_server = s;
+
+        if (m->unicast_scope)
+                dns_cache_flush(&m->unicast_scope->cache);
+
+        return s;
+}
+
+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 chose 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);
+        }
+
+        return m->current_dns_server;
+}
+
+void manager_next_dns_server(Manager *m) {
+        assert(m);
+
+        /* If there's currently no DNS server set, then the next
+         * manager_get_dns_server() will find one */
+        if (!m->current_dns_server)
+                return;
+
+        /* Change to the next one */
+        if (m->current_dns_server->servers_next) {
+                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);
+}