Warn if failed to request 'shadow port'.

Author: burningtnt

src/controller/rooms/experimental/room.rs

@@ -372,7 +372,10 @@ pub fn start_guest(room: Room, player: Option<String>, capture: AppStateCapture)
 
         // To maximum compatibility, try to request the identical port.
         // If failed, use a dynamic free port instead.
-        let local_port = PortRequest::request_specific(port).unwrap_or_else(|| PortRequest::Minecraft.request());
+        let local_port = PortRequest::request_specific(port).unwrap_or_else(|e| {
+            logging!("RoomExperiment", "Unable to request shadow port {} on client: {:?}. Mods requiring UDP socket like SimpleVoiceChat may go wrong.", port, e);
+            PortRequest::Minecraft.request()
+        });
 
         if !easytier.add_port_forward(&{
             let locals = [

src/ports.rs

@@ -1,3 +1,4 @@
+use std::io;
 use std::net::{Ipv4Addr, TcpListener};
 
 #[repr(u8)]
@@ -9,11 +10,10 @@ pub enum PortRequest {
 }
 
 impl PortRequest {
-    pub fn request_specific(port: u16) -> Option<u16> {
+    pub fn request_specific(port: u16) -> io::Result<u16> {
         TcpListener::bind((Ipv4Addr::LOCALHOST, port))
             .and_then(|socket| socket.local_addr())
             .map(|address| address.port())
-            .ok()
     }
 
     pub fn request(self) -> u16 {