Derive correct UUID for offline players in lobby logic (2/2)

src/mc/uuid.rs

@@ -6,7 +6,7 @@ const OFFLINE_PLAYER_NAMESPACE: &str = "OfflinePlayer:";
 
 /// Get UUID for given player username.
 pub fn player_uuid(username: &str) -> Uuid {
-    Uuid::from_bytes(jdk_name_uuid_from_bytes(username.as_bytes()))
+    java_name_uuid_from_bytes(username.as_bytes())
 }
 
 /// Get UUID for given offline player username.
@@ -14,13 +14,20 @@ pub fn offline_player_uuid(username: &str) -> Uuid {
     player_uuid(&format!("{}{}", OFFLINE_PLAYER_NAMESPACE, username))
 }
 
-/// Java's `UUID.nameUUIDFromBytes`.
+/// Java's `UUID.nameUUIDFromBytes`
 ///
 /// Static factory to retrieve a type 3 (name based) `Uuid` based on the specified byte array.
 ///
-/// Ported from: https://github.com/AdoptOpenJDK/openjdk-jdk8u/blob/9a91972c76ddda5c1ce28b50ca38cbd8a30b7a72/jdk/src/share/classes/java/util/UUID.java#L153-L175
-fn jdk_name_uuid_from_bytes(data: &[u8]) -> [u8; 16] {
+/// Ported from: https://git.io/J1b6A
+fn java_name_uuid_from_bytes(data: &[u8]) -> Uuid {
     let mut hasher = Md5::new();
     hasher.update(data);
-    hasher.finalize().into()
+    let mut md5: [u8; 16] = hasher.finalize().into();
+
+    md5[6] &= 0x0f; // clear version
+    md5[6] |= 0x30; // set to version 3
+    md5[8] &= 0x3f; // clear variant
+    md5[8] |= 0x80; // set to IETF variant
+
+    Uuid::from_bytes(md5)
 }