fix(proxy): forward backend register/unregister packets to client (minekube#672)

Author: Trirrin

pkg/edition/java/proxy/session_backend_play.go

@@ -190,11 +190,9 @@ func (b *backendPlaySessionHandler) handlePluginMessage(packet *plugin.Message,
 		return
 	}
 
-	// Register and unregister packets are simply forwarded to the server as-is.
+	// Register and unregister packets from the backend must be forwarded to the client as-is.
 	if plugin.IsRegister(packet) || plugin.IsUnregister(packet) {
-		if serverMc, ok := b.serverConn.ensureConnected(); ok {
-			_ = serverMc.WritePacket(packet)
-		}
+		b.forwardToPlayer(pc, packet)
 		return
 	}
 

pkg/edition/java/proxy/session_backend_play_test.go

@@ -0,0 +1,95 @@
+package proxy
+
+import (
+	"context"
+	"net"
+	"testing"
+
+	"github.com/go-logr/logr"
+	"go.minekube.com/gate/pkg/edition/java/netmc"
+	"go.minekube.com/gate/pkg/edition/java/proto/packet/plugin"
+	"go.minekube.com/gate/pkg/edition/java/proto/state"
+	"go.minekube.com/gate/pkg/edition/java/proto/version"
+	"go.minekube.com/gate/pkg/edition/java/proxy/bungeecord"
+	"go.minekube.com/gate/pkg/edition/java/proxy/phase"
+	"go.minekube.com/gate/pkg/gate/proto"
+)
+
+func TestBackendPlayRegisterForwardsToPlayer(t *testing.T) {
+	playerConn := &testMinecraftConn{}
+	player := &connectedPlayer{
+		MinecraftConn: playerConn,
+		log:           logr.Discard(),
+	}
+	serverConn := &serverConnection{
+		player: player,
+		log:    logr.Discard(),
+	}
+	handler := &backendPlaySessionHandler{
+		serverConn:                 serverConn,
+		bungeeCordMessageResponder: bungeecord.NopMessageResponder,
+		log:                        logr.Discard(),
+	}
+
+	register := &plugin.Message{
+		Channel: plugin.RegisterChannel,
+		Data:    []byte("axiom:hello"),
+	}
+	handler.handlePluginMessage(register, nil)
+
+	if len(playerConn.writtenPackets) != 1 {
+		t.Fatalf("expected register packet to be written to player once, got %d", len(playerConn.writtenPackets))
+	}
+	got, ok := playerConn.writtenPackets[0].(*plugin.Message)
+	if !ok {
+		t.Fatalf("expected plugin message, got %T", playerConn.writtenPackets[0])
+	}
+	if got.Channel != register.Channel {
+		t.Fatalf("expected channel %q, got %q", register.Channel, got.Channel)
+	}
+	if string(got.Data) != string(register.Data) {
+		t.Fatalf("expected payload %q, got %q", string(register.Data), string(got.Data))
+	}
+}
+
+type testMinecraftConn struct {
+	writtenPackets []proto.Packet
+}
+
+func (t *testMinecraftConn) Context() context.Context { return context.Background() }
+func (t *testMinecraftConn) Close() error             { return nil }
+func (t *testMinecraftConn) State() *state.Registry   { return state.Play }
+func (t *testMinecraftConn) Protocol() proto.Protocol { return version.Minecraft_1_20_3.Protocol }
+func (t *testMinecraftConn) RemoteAddr() net.Addr     { return &net.TCPAddr{} }
+func (t *testMinecraftConn) LocalAddr() net.Addr      { return &net.TCPAddr{} }
+func (t *testMinecraftConn) Type() phase.ConnectionType {
+	return phase.Vanilla
+}
+func (t *testMinecraftConn) SetType(phase.ConnectionType)               {}
+func (t *testMinecraftConn) ActiveSessionHandler() netmc.SessionHandler { return nil }
+func (t *testMinecraftConn) SetActiveSessionHandler(*state.Registry, netmc.SessionHandler) {
+}
+func (t *testMinecraftConn) SwitchSessionHandler(*state.Registry) bool { return true }
+func (t *testMinecraftConn) AddSessionHandler(*state.Registry, netmc.SessionHandler) {
+}
+func (t *testMinecraftConn) SetAutoReading(bool)               {}
+func (t *testMinecraftConn) SetProtocol(proto.Protocol)        {}
+func (t *testMinecraftConn) SetState(*state.Registry)          {}
+func (t *testMinecraftConn) SetCompressionThreshold(int) error { return nil }
+func (t *testMinecraftConn) EnableEncryption([]byte) error     { return nil }
+func (t *testMinecraftConn) WritePacket(packet proto.Packet) error {
+	t.writtenPackets = append(t.writtenPackets, packet)
+	return nil
+}
+func (t *testMinecraftConn) Write([]byte) error { return nil }
+func (t *testMinecraftConn) BufferPacket(packet proto.Packet) error {
+	t.writtenPackets = append(t.writtenPackets, packet)
+	return nil
+}
+func (t *testMinecraftConn) BufferPayload([]byte) error { return nil }
+func (t *testMinecraftConn) Flush() error               { return nil }
+func (t *testMinecraftConn) Reader() netmc.Reader       { return nil }
+func (t *testMinecraftConn) Writer() netmc.Writer       { return nil }
+func (t *testMinecraftConn) EnablePlayPacketQueue()     {}
+
+var _ netmc.MinecraftConn = (*testMinecraftConn)(nil)