feat: Add Minecraft handshake intent rewriting & transfer rule support

Author: layou233

common/mcprotocol/enum.go

@@ -1,7 +1,14 @@
 package mcprotocol
 
 const (
-	NextStateStatus = iota + 1
-	NextStateLogin
-	NextStateTransfer // added in 1.20.5 (24w03a)
+	IntentStatus = iota + 1
+	IntentLogin
+	IntentTransfer // added in 1.20.5 (24w03a)
+)
+
+// Deprecated: Next State has been renamed to Intent.
+const (
+	NextStateStatus   = IntentStatus
+	NextStateLogin    = IntentLogin
+	NextStateTransfer = IntentTransfer
 )

config/router.go

@@ -26,6 +26,7 @@ type RuleRewrite struct {
 type ruleRewriteMinecraft struct {
 	Hostname string `json:",omitempty"`
 	Port     uint16 `json:",omitempty"`
+	Intent   int8   `json:",omitempty"`
 }
 
 type RuleDomain struct {

protocol/minecraft/outbound.go

@@ -238,7 +238,7 @@ func (o *Outbound) InjectConnection(ctx context.Context, conn *bufio.CachedConn,
 		conn.Rewind(metadata.Minecraft.SniffPosition)
 	}
 	switch metadata.Minecraft.NextState {
-	case mcprotocol.NextStateStatus:
+	case mcprotocol.IntentStatus:
 		// skip Status Request packet
 		_, err := conn.Peek(2)
 		if err != nil {
@@ -282,7 +282,7 @@ func (o *Outbound) InjectConnection(ctx context.Context, conn *bufio.CachedConn,
 			mcprotocol.VarInt(metadata.Minecraft.ProtocolVersion).WriteToBuffer(buffer)
 			mcprotocol.WriteString(buffer, hostname)
 			binary.BigEndian.PutUint16(buffer.Extend(2), port)
-			buffer.WriteByte(mcprotocol.NextStateStatus)
+			buffer.WriteByte(mcprotocol.IntentStatus)
 			mcprotocol.AppendPacketLength(buffer, buffer.Len())
 			// construct status packet
 			buffer.WriteByte(1)
@@ -337,7 +337,7 @@ func (o *Outbound) InjectConnection(ctx context.Context, conn *bufio.CachedConn,
 			return nil
 		}
 
-	case mcprotocol.NextStateLogin:
+	case mcprotocol.IntentLogin:
 		buffer := buf.New()
 		buffer.Reset(mcprotocol.MaxVarIntLen)
 		if o.config.Minecraft.NameAccess.Mode != access.DefaultMode {
@@ -412,7 +412,7 @@ func (o *Outbound) InjectConnection(ctx context.Context, conn *bufio.CachedConn,
 		mcprotocol.VarInt(metadata.Minecraft.ProtocolVersion).WriteToBuffer(buffer)
 		mcprotocol.WriteString(buffer, hostname)
 		binary.BigEndian.PutUint16(buffer.Extend(2), port)
-		buffer.WriteByte(mcprotocol.NextStateLogin)
+		buffer.WriteByte(mcprotocol.IntentLogin)
 		mcprotocol.AppendPacketLength(buffer, buffer.Len())
 		// write handshake and login packet
 		cache := conn.Cache()
@@ -431,7 +431,7 @@ func (o *Outbound) InjectConnection(ctx context.Context, conn *bufio.CachedConn,
 		o.onlineCount.Add(-1)
 		return err
 
-	case mcprotocol.NextStateTransfer:
+	case mcprotocol.IntentTransfer:
 		// TODO: Minecraft transfer support
 		conn.Conn.(*net.TCPConn).SetLinger(0)
 		return conn.Close()

protocol/minecraft/sniff.go

@@ -71,21 +71,21 @@ func SniffClientHandshake(conn bufio.PeekConn, metadata *adapter.Metadata) error
 		return ErrBadPacket
 	}
 
-	nextState, err := buffer.ReadByte()
+	intent, err := buffer.ReadByte()
 	if err != nil {
 		return common.Cause("read next state: ", err)
 	}
-	switch nextState {
-	case mcprotocol.NextStateLogin,
-		mcprotocol.NextStateStatus,
-		mcprotocol.NextStateTransfer:
+	switch intent {
+	case mcprotocol.IntentLogin,
+		mcprotocol.IntentStatus,
+		mcprotocol.IntentTransfer:
 	default:
 		return ErrBadPacket
 	}
-	metadata.Minecraft.NextState = int8(nextState)
+	metadata.Minecraft.NextState = int8(intent)
 
 	metadata.Minecraft.SniffPosition = conn.CurrentPosition()
-	if nextState == mcprotocol.NextStateStatus {
+	if intent == mcprotocol.IntentStatus {
 		// status packet
 		conn.SetReadDeadline(time.Now().Add(10 * time.Second))
 		_, err = conn.Peek(2)

route/router.go

@@ -106,6 +106,9 @@ func (r *Router) HandleConnection(conn net.Conn, metadata *adapter.Metadata) {
 					if ruleConfig.Rewrite.Minecraft.Port > 0 {
 						metadata.Minecraft.RewrittenPort = ruleConfig.Rewrite.Minecraft.Port
 					}
+					if ruleConfig.Rewrite.Minecraft.Intent > 0 {
+						metadata.Minecraft.NextState = ruleConfig.Rewrite.Minecraft.Intent
+					}
 				}
 			}
 			// handle outbound

route/rule.go

@@ -47,6 +47,8 @@ func NewRule(logger *log.Logger, config *config.Rule, listMap map[string]set.Str
 		return NewMinecraftPlayerNameRule(config, listMap)
 	case "MinecraftStatus":
 		return NewMinecraftStatusRule(config)
+	case "MinecraftTransfer":
+		return NewMinecraftTransferRule(config)
 	}
 	if len(ruleRegistry) > 0 && strings.HasPrefix(config.Type, typeCustomPrefix) {
 		typeName := strings.TrimPrefix(config.Type, typeCustomPrefix)

route/rule_minecraft.go

@@ -88,7 +88,33 @@ func (r *RuleMinecraftStatus) Config() *config.Rule {
 
 func (r *RuleMinecraftStatus) Match(metadata *adapter.Metadata) (match bool) {
 	if metadata.Minecraft != nil {
-		match = metadata.Minecraft.NextState == mcprotocol.NextStateStatus
+		match = metadata.Minecraft.NextState == mcprotocol.IntentStatus
+	}
+	if r.config.Invert {
+		match = !match
+	}
+	return
+}
+
+type RuleMinecraftTransfer struct {
+	config *config.Rule
+}
+
+var _ Rule = (*RuleMinecraftTransfer)(nil)
+
+func NewMinecraftTransferRule(newConfig *config.Rule) (Rule, error) {
+	return &RuleMinecraftTransfer{
+		config: newConfig,
+	}, nil
+}
+
+func (r *RuleMinecraftTransfer) Config() *config.Rule {
+	return r.config
+}
+
+func (r *RuleMinecraftTransfer) Match(metadata *adapter.Metadata) (match bool) {
+	if metadata.Minecraft != nil {
+		match = metadata.Minecraft.NextState == mcprotocol.IntentTransfer
 	}
 	if r.config.Invert {
 		match = !match