protocol: add Filter::contains_flags

master/src/master_server.rs

@@ -347,9 +347,9 @@ impl MasterServer {
 
                     self.send_server_list(from, p.filter.key, &self.filtered_servers)?;
 
-                    if !p.filter.flags_mask.contains(FilterFlags::NAT)
+                    // NOTE: If NAT is not set in a filter then by default the client is announced
-                        || p.filter.flags.contains(FilterFlags::NAT)
+                    // to filtered servers behind NAT.
-                    {
+                    if p.filter.contains_flags(FilterFlags::NAT).unwrap_or(true) {
                         self.send_client_to_nat_servers(from, &self.filtered_servers_nat)?;
                     }
 

protocol/src/filter.rs

@@ -186,6 +186,15 @@ impl Filter<'_> {
         self.flags_mask.insert(flag);
     }
 
+    /// Test if all `other` flags are set in `flags_mask` and in `flags`.
+    pub fn contains_flags(&self, other: FilterFlags) -> Option<bool> {
+        if self.flags_mask.contains(other) {
+            Some(self.flags.contains(other))
+        } else {
+            None
+        }
+    }
+
     /// Returns `true` if a server matches the filter.
     pub fn matches(&self, _addr: SocketAddrV4, info: &ServerInfo) -> bool {
         !((info.flags & self.flags_mask) != self.flags