Support handshake data validator (#69)

cluster/handler.go

@@ -252,6 +252,10 @@ func (h *LocalHandler) handle(conn net.Conn) {
 func (h *LocalHandler) processPacket(agent *agent, p *packet.Packet) error {
 	switch p.Type {
 	case packet.Handshake:
+		if err := env.HandshakeValidator(p.Data); err != nil {
+			return err
+		}
+
 		if _, err := agent.conn.Write(hrd); err != nil {
 			return err
 		}

internal/env/env.go

@@ -32,12 +32,13 @@ import (
 )
 
 var (
-	Wd          string                   // working path
-	Die         chan bool                // wait for end application
-	Heartbeat   time.Duration            // Heartbeat internal
-	CheckOrigin func(*http.Request) bool // check origin when websocket enabled
-	Debug       bool                     // enable Debug
-	WSPath      string                   // WebSocket path(eg: ws://127.0.0.1/WSPath)
+	Wd                 string                   // working path
+	Die                chan bool                // wait for end application
+	Heartbeat          time.Duration            // Heartbeat internal
+	CheckOrigin        func(*http.Request) bool // check origin when websocket enabled
+	Debug              bool                     // enable Debug
+	WSPath             string                   // WebSocket path(eg: ws://127.0.0.1/WSPath)
+	HandshakeValidator func([]byte) error       // When you need to verify the custom data of the handshake request
 
 	// timerPrecision indicates the precision of timer, default is time.Second
 	TimerPrecision = time.Second
@@ -56,5 +57,6 @@ func init() {
 	Heartbeat = 30 * time.Second
 	Debug = false
 	CheckOrigin = func(_ *http.Request) bool { return true }
+	HandshakeValidator = func(_ []byte) error { return nil }
 	Serializer = protobuf.NewSerializer()
 }

options.go

@@ -145,3 +145,10 @@ func WithLogger(l log.Logger) Option {
 		log.SetLogger(l)
 	}
 }
+
+// WithHandshakeValidator sets the function that Verify `handshake` data
+func WithHandshakeValidator(fn func([]byte) error) Option {
+	return func(opt *cluster.Options) {
+		env.HandshakeValidator = fn
+	}
+}