Send reply to ServerHello: REGISTER and FML|HS ClientHello

Author: iceiix

src/server/mod.rs

@@ -686,11 +686,34 @@ impl Server {
             "FML|HS" => {
                 let msg = plugin_messages::FmlHs::from_message(&data);
                 println!("FML|HS msg={:?}", msg);
+                match msg {
+                    plugin_messages::FmlHs::ServerHello { fml_protocol_version, override_dimension } => {
+                        println!("Received FML|HS ServerHello {} {:?}", fml_protocol_version, override_dimension);
+
+                        self.write_plugin_message("REGISTER", "FML|HS\0FML\0FML|MP\0FML\0FORGE".as_bytes());
+                        self.write_plugin_message("FML|HS", &plugin_messages::FmlHs::ClientHello { fml_protocol_version }.as_message());
+                    },
+                    _ => (),
+                }
             }
             _ => ()
         }
     }
 
+    fn write_plugin_message(&mut self, channel: &str, data: &[u8]) {
+        if self.protocol_version >= 47 {
+            self.write_packet(packet::play::serverbound::PluginMessageServerbound {
+                channel: channel.to_string(),
+                data: data.to_vec(),
+            });
+        } else {
+            self.write_packet(packet::play::serverbound::PluginMessageServerbound_i16 {
+                channel: channel.to_string(),
+                data: crate::protocol::LenPrefixedBytes::<i16>::new(data.to_vec()),
+            });
+        }
+    }
+
     fn on_game_join_i32_viewdistance(&mut self, join: packet::play::clientbound::JoinGame_i32_ViewDistance) {
         self.on_game_join(join.gamemode, join.entity_id)
     }
@@ -726,6 +749,7 @@ impl Server {
         let brand = plugin_messages::Brand {
                 brand: "Steven".into(),
             };
+        // TODO: refactor with write_plugin_message
         if self.protocol_version >= 47 {
             self.write_packet(brand.as_message());
         } else {

src/server/plugin_messages.rs

@@ -31,6 +31,15 @@ pub enum FmlHs<'a> {
 }
 
 impl<'a> FmlHs<'a> {
+    pub fn as_message(&'a self) -> Vec<u8> {
+        match self {
+            FmlHs::ClientHello { fml_protocol_version } => {
+                vec![*fml_protocol_version as u8]
+            },
+            _ => unimplemented!()
+        }
+    }
+
     pub fn from_message(data: &[u8]) -> FmlHs<'a> {
         // https://wiki.vg/Minecraft_Forge_Handshake
         let discriminator = data[0];