fix: #4070 Host called command has null sender connection when server owns object

Assets/Mirror/Editor/Weaver/Processors/CommandProcessor.cs

@@ -91,10 +91,10 @@ public static MethodDefinition ProcessCommandCall(WeaverTypes weaverTypes, Write
                 ParameterDefinition param = md.Parameters[i];
                 if (NetworkBehaviourProcessor.IsSenderConnection(param, RemoteCallType.Command))
                 {
-                    // load 'this.'
-                    worker.Emit(OpCodes.Ldarg_0);
-                    // call get_connectionToClient
-                    worker.Emit(OpCodes.Call, weaverTypes.NetworkBehaviourConnectionToClientReference);
+                    // Server-owned object => no owner connection (connectionToClient is null).
+                    // Host calling [Command] should use NetworkServer.localConnection as sender.
+                    // Load NetworkServer.localConnection
+                    worker.Emit(OpCodes.Call, weaverTypes.NetworkServerLocalConnectionReference);
                 }
                 else
                 {

Assets/Mirror/Editor/Weaver/WeaverTypes.cs

@@ -17,6 +17,7 @@ public class WeaverTypes
         public MethodReference GetWriterReference;
         public MethodReference ReturnWriterReference;
 
+        public MethodReference NetworkServerLocalConnectionReference;
         public MethodReference NetworkClientConnectionReference;
 
         public MethodReference RemoteCallDelegateConstructor;
@@ -86,6 +87,7 @@ public WeaverTypes(AssemblyDefinition assembly, Logger Log, ref bool WeavingFail
 
             TypeReference NetworkServerType = Import(typeof(NetworkServer));
             NetworkServerGetActive = Resolvers.ResolveMethod(NetworkServerType, assembly, Log, "get_active", ref WeavingFailed);
+            NetworkServerLocalConnectionReference = Resolvers.ResolveMethod(NetworkServerType, assembly, Log, "get_localConnection", ref WeavingFailed);
 
             TypeReference NetworkClientType = Import(typeof(NetworkClient));
             NetworkClientGetActive = Resolvers.ResolveMethod(NetworkClientType, assembly, Log, "get_active", ref WeavingFailed);

Assets/Mirror/Tests/Editor/NetworkServer/NetworkServerTest.cs

@@ -851,10 +851,9 @@ public void SendCommand_RequiresAuthority()
             Assert.That(serverComponent.called, Is.EqualTo(0));
         }
 
-        // [Command] with NetworkConnectionToClient parameter on host should be automatically set to .connectionToClient.
-        // this is what happens in server-only mode too.
+        // Command with NetworkConnectionToClient arg expects a non-null connection arg when called on the client owned object.
         [Test]
-        public void SendCommand_ConnectionToClient_HostMode()
+        public void SendCommand_ClientOwnedObject_ConnectionNotNull()
         {
             // listen & connect
             NetworkServer.Listen(1);
@@ -871,10 +870,35 @@ public void SendCommand_ConnectionToClient_HostMode()
 
             // on server it should be != null
             Assert.That(comp.conn, !Is.Null);
+            // Host player-owned object: sender == connectionToClient (host's localConnection).
             Assert.That(comp.conn, Is.EqualTo(comp.connectionToClient));
             Assert.That(comp.called, Is.EqualTo(1));
         }
 
+        // Command with NetworkConnectionToClient arg expects a non-null connection arg when called on the server owned object.
+        [Test]
+        public void SendCommand_ServerOwnedObject_ConnectionNotNull()
+        {
+            // listen & connect
+            NetworkServer.Listen(1);
+            ConnectHostClientBlockingAuthenticatedAndReady();
+
+            // add an identity with two networkbehaviour components
+            // spawned, otherwise command handler won't find it in .spawned.
+            // WITHOUT OWNER (SERVER-OWNED OBJECT)
+            CreateNetworkedAndSpawn(out GameObject _, out NetworkIdentity _, out CommandWithConnectionToClientNetworkBehaviour comp, ownerConnection: null);
+
+            // call the command, which has a 'NetworkConnectionToClient = null' default parameter
+            comp.TestCommand();
+            ProcessMessages();
+
+            // on server it should be != null
+            Assert.That(comp.conn, !Is.Null);
+            // Host mode + server-owned object: connectionToClient is null, so sender must be localConnection.
+            Assert.That(comp.conn, Is.EqualTo(NetworkServer.localConnection));
+            Assert.That(comp.called, Is.EqualTo(1));
+        }
+
         [Test]
         public void SendToAll()
         {