resolved: do not start LLMNR or mDNS stack when no network enables them

When no network enables LLMNR or mDNS, it is not necessary to create
LLMNR or mDNS related sockets. So, let's create them only when
LLMNR- or mDNS-enabled network becomes active or at least one network
enables `LLMNR=` or `MulticastDNS=` options.

2 files changed, 17 insertions, 8 deletions

diff --git a/src/resolve/resolved-link.c b/src/resolve/resolved-link.c
index 3f7f9035cf..d06096f3f2 100644
--- a/src/resolve/resolved-link.c
+++ b/src/resolve/resolved-link.c
@@ -28,6 +28,8 @@
 #include "mkdir.h"
 #include "parse-util.h"
 #include "resolved-link.h"
+#include "resolved-llmnr.h"
+#include "resolved-mdns.h"
 #include "string-util.h"
 #include "strv.h"
 
@@ -523,10 +525,25 @@ static void link_read_settings(Link *l) {
 }
 
 int link_update(Link *l) {
+        int r;
+
         assert(l);
 
         link_read_settings(l);
         link_load_user(l);
+
+        if (l->llmnr_support != RESOLVE_SUPPORT_NO) {
+                r = manager_llmnr_start(l->manager);
+                if (r < 0)
+                        return r;
+        }
+
+        if (l->mdns_support != RESOLVE_SUPPORT_NO) {
+                r = manager_mdns_start(l->manager);
+                if (r < 0)
+                        return r;
+        }
+
         link_allocate_scopes(l);
         link_add_rrs(l, false);
 
diff --git a/src/resolve/resolved-manager.c b/src/resolve/resolved-manager.c
index c4e4409fe3..9db8b8f616 100644
--- a/src/resolve/resolved-manager.c
+++ b/src/resolve/resolved-manager.c
@@ -612,14 +612,6 @@ int manager_start(Manager *m) {
         if (r < 0)
                 return r;
 
-        r = manager_llmnr_start(m);
-        if (r < 0)
-                return r;
-
-        r = manager_mdns_start(m);
-        if (r < 0)
-                return r;
-
         return 0;
 }