Dynamically build lobby dimension from probed server dimension codec

src/lobby.rs

@@ -30,7 +30,7 @@ use tokio::time;
 
 use crate::config::*;
 use crate::forge;
-use crate::mc::{self, uuid};
+use crate::mc::{self, dimension, uuid};
 use crate::net;
 use crate::proto;
 use crate::proto::client::{Client, ClientInfo, ClientState};
@@ -273,13 +273,14 @@ async fn send_lobby_join_game(
     writer: &mut WriteHalf<'_>,
     server: &Server,
 ) -> Result<(), ()> {
-    // Grab probed dimension codec
+    // Get dimension codec and build lobby dimension
     let dimension_codec: CompoundTag =
         if let Some(ref join_game) = server.probed_join_game.lock().await.as_ref() {
             join_game.dimension_codec.clone()
         } else {
-            snbt_to_compound_tag(include_str!("../res/dimension_codec.snbt"))
+            dimension::lobby_default_dimension_codec()
         };
+    let dimension: CompoundTag = dimension::lobby_dimension(&dimension_codec);
 
     // Send Minecrafts default states, slightly customised for lobby world
     packet::write_packet(
@@ -299,7 +300,7 @@ async fn send_lobby_join_game(
                     "minecraft:the_end".into(),
                 ],
                 dimension_codec,
-                dimension: snbt_to_compound_tag(include_str!("../res/dimension.snbt")),
+                dimension,
                 world_name: "lazymc:lobby".into(),
                 hashed_seed: 0,
                 max_players: status.as_ref().map(|s| s.players.max as i32).unwrap_or(20),
@@ -858,26 +859,3 @@ async fn drain_stream(reader: &mut ReadHalf<'_>) -> Result<(), ()> {
         }
     }
 }
-
-/// Read NBT CompoundTag from SNBT.
-fn snbt_to_compound_tag(data: &str) -> CompoundTag {
-    use quartz_nbt::io::{write_nbt, Flavor};
-    use quartz_nbt::snbt;
-
-    // Parse SNBT data
-    let compound = snbt::parse(data).expect("failed to parse SNBT");
-
-    // Encode to binary
-    let mut binary = Vec::new();
-    write_nbt(&mut binary, None, &compound, Flavor::Uncompressed)
-        .expect("failed to encode NBT CompoundTag as binary");
-
-    // Parse binary with usable NBT create
-    bin_to_compound_tag(&mut &*binary)
-}
-
-/// Read NBT CompoundTag from SNBT.
-fn bin_to_compound_tag(data: &[u8]) -> CompoundTag {
-    use nbt::decode::read_compound_tag;
-    read_compound_tag(&mut &*data).unwrap()
-}

src/mc/dimension.rs

@@ -0,0 +1,112 @@
+use nbt::CompoundTag;
+
+/// Create lobby dimension from the given codec.
+///
+/// This creates a dimension suitable for the lobby that should be suitable for the current server
+/// version.
+pub fn lobby_dimension(codec: &CompoundTag) -> CompoundTag {
+    // Retrieve dimension types from codec
+    let dimension_types = match codec.get_compound_tag("minecraft:dimension_type") {
+        Ok(types) => types,
+        Err(_) => return lobby_default_dimension(),
+    };
+
+    // Get base dimension
+    let mut base = lobby_base_dimension(dimension_types);
+
+    // Change known properties on base to get more desirable dimension
+    base.insert_i8("piglin_safe", 1);
+    base.insert_f32("ambient_light", 0.0);
+    // base.insert_str("infiniburn", "minecraft:infiniburn_end");
+    base.insert_i8("respawn_anchor_works", 0);
+    base.insert_i8("has_skylight", 0);
+    base.insert_i8("bed_works", 0);
+    base.insert_str("effects", "minecraft:the_end");
+    base.insert_i64("fixed_time", 0);
+    base.insert_i8("has_raids", 0);
+    base.insert_i32("min_y", 0);
+    base.insert_i32("height", 1);
+    base.insert_i32("logical_height", 1);
+    base.insert_f64("coordinate_scale", 1.0);
+    base.insert_i8("ultrawarm", 0);
+    base.insert_i8("has_ceiling", 0);
+
+    base
+}
+
+/// Get lobby base dimension.
+///
+/// This retrieves the most desirable dimension to use as base for the lobby from the given list of
+/// `dimension_types`.
+///
+/// If no dimension is found in the given tag, a default one will be returned.
+fn lobby_base_dimension(dimension_types: &CompoundTag) -> CompoundTag {
+    // The dimension types we prefer the most, in order
+    let preferred = vec![
+        "minecraft:the_end",
+        "minecraft:the_nether",
+        "minecraft:the_overworld",
+    ];
+
+    let dimensions = dimension_types.get_compound_tag_vec("value").unwrap();
+
+    for name in preferred {
+        if let Some(dimension) = dimensions
+            .iter()
+            .find(|d| d.get_str("name").map(|n| n == name).unwrap_or(false))
+        {
+            if let Ok(dimension) = dimension.get_compound_tag("element") {
+                return dimension.clone();
+            }
+        }
+    }
+
+    // Return first dimension
+    if let Some(dimension) = dimensions.first() {
+        if let Ok(dimension) = dimension.get_compound_tag("element") {
+            return dimension.clone();
+        }
+    }
+
+    // Fall back to default dimension
+    lobby_default_dimension()
+}
+
+/// Default lobby dimension codec from resource file.
+///
+/// This likely breaks if the Minecraft version doesn't match exactly.
+/// Please use an up-to-date coded from the server instead.
+pub fn lobby_default_dimension_codec() -> CompoundTag {
+    snbt_to_compound_tag(include_str!("../../res/dimension_codec.snbt"))
+}
+
+/// Default lobby dimension from resource file.
+///
+/// This likely breaks if the Minecraft version doesn't match exactly.
+/// Please use `lobby_dimension` with an up-to-date coded from the server instead.
+fn lobby_default_dimension() -> CompoundTag {
+    snbt_to_compound_tag(include_str!("../../res/dimension.snbt"))
+}
+
+/// Read NBT CompoundTag from SNBT.
+fn snbt_to_compound_tag(data: &str) -> CompoundTag {
+    use quartz_nbt::io::{write_nbt, Flavor};
+    use quartz_nbt::snbt;
+
+    // Parse SNBT data
+    let compound = snbt::parse(data).expect("failed to parse SNBT");
+
+    // Encode to binary
+    let mut binary = Vec::new();
+    write_nbt(&mut binary, None, &compound, Flavor::Uncompressed)
+        .expect("failed to encode NBT CompoundTag as binary");
+
+    // Parse binary with usable NBT create
+    bin_to_compound_tag(&mut &*binary)
+}
+
+/// Read NBT CompoundTag from SNBT.
+fn bin_to_compound_tag(data: &[u8]) -> CompoundTag {
+    use nbt::decode::read_compound_tag;
+    read_compound_tag(&mut &*data).unwrap()
+}

src/mc/mod.rs

@@ -1,4 +1,6 @@
 pub mod ban;
+#[cfg(feature = "lobby")]
+pub mod dimension;
 pub mod favicon;
 #[cfg(feature = "rcon")]
 pub mod rcon;