set up unbound dns for server

modules/server/continuwuity.nix

@@ -59,6 +59,8 @@
             url_preview_max_spider_size = 2097152;
             max_request_size = 524288000;
             db_cache_capacity_mb = 2056;
+
+            query_over_tcp_only = true;
             dns_cache_entries = 0;
 
             allow_public_room_directory_over_federation = true;

modules/server/dns.nix

@@ -0,0 +1,12 @@
+{
+  services.unbound = {
+    enable = true;
+    settings = {
+      server = {
+        rrset-cache-size = "64M";
+        msg-cache-size = "64M";
+        discard-timeout = 4800;
+      };
+    };
+  };
+}