#3438: Fix possible race condition in duplicate player check

SpigotMC · Nov 1, 2023 · f5157f1 · f5157f1
1 parent df20eff
commit f5157f1
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Showing 4 changed files with 14 additions and 4 deletions.
diff --git a/proxy/src/main/java/net/md_5/bungee/BungeeCord.java b/proxy/src/main/java/net/md_5/bungee/BungeeCord.java
@@ -753,7 +753,7 @@ public void broadcast(BaseComponent message)
         }
     }
 
-    public void addConnection(UserConnection con)
+    public boolean addConnection(UserConnection con)
     {
         UUID offlineId = con.getPendingConnection().getOfflineId();
         if ( offlineId != null && offlineId.version() != 3 )
@@ -763,13 +763,18 @@ public void addConnection(UserConnection con)
         connectionLock.writeLock().lock();
         try
         {
+            if ( connections.containsKey( con.getName() ) || connectionsByUUID.containsKey( con.getUniqueId() ) || connectionsByOfflineUUID.containsKey( offlineId ) )
+            {
+                return false;
+            }
             connections.put( con.getName(), con );
             connectionsByUUID.put( con.getUniqueId(), con );
             connectionsByOfflineUUID.put( offlineId, con );
         } finally
         {
             connectionLock.writeLock().unlock();
         }
+        return true;
     }
 
     public void removeConnection(UserConnection con)

diff --git a/proxy/src/main/java/net/md_5/bungee/UserConnection.java b/proxy/src/main/java/net/md_5/bungee/UserConnection.java
@@ -153,7 +153,7 @@ public void sendPacket(DefinedPacket packet)
         }
     };
 
-    public void init()
+    public boolean init()
     {
         this.entityRewrite = EntityMap.getEntityMap( getPendingConnection().getVersion() );
 
@@ -172,6 +172,8 @@ public void init()
 
         // Set whether the connection has a 1.8 FML marker in the handshake.
         forgeClientHandler.setFmlTokenInHandshake( this.getPendingConnection().getExtraDataInHandshake().contains( ForgeConstants.FML_HANDSHAKE_TOKEN ) );
+
+        return BungeeCord.getInstance().addConnection( this );
     }
 
     public void sendPacket(PacketWrapper packet)

diff --git a/proxy/src/main/java/net/md_5/bungee/connection/InitialHandler.java b/proxy/src/main/java/net/md_5/bungee/connection/InitialHandler.java
@@ -613,7 +613,11 @@ public void run()
 
     private void finish2()
     {
-        userCon.init();
+        if ( !userCon.init() )
+        {
+            disconnect( bungee.getTranslation( "already_connected_proxy" ) );
+            return;
+        }
 
         ch.getHandle().pipeline().get( HandlerBoss.class ).setHandler( new UpstreamBridge( bungee, userCon ) );
         bungee.getPluginManager().callEvent( new PostLoginEvent( userCon ) );

diff --git a/proxy/src/main/java/net/md_5/bungee/connection/UpstreamBridge.java b/proxy/src/main/java/net/md_5/bungee/connection/UpstreamBridge.java
@@ -54,7 +54,6 @@ public UpstreamBridge(ProxyServer bungee, UserConnection con)
         this.bungee = bungee;
         this.con = con;
 
-        BungeeCord.getInstance().addConnection( con );
         con.getTabListHandler().onConnect();
     }