remove string casts

compare byte slices

pkg/udpproxy/session.go

@@ -29,6 +29,7 @@ func newSession(caddr *net.UDPAddr, raddr *net.UDPAddr, proxyConn *net.UDPConn)
 		proxyConn:  proxyConn,
 		caddr:      caddr,
 		updateTime: time.Now(),
+		validator:  newValidator(),
 	}
 
 	go session.listen()
@@ -64,7 +65,11 @@ func (s *session) proxyFrom(buf []byte) error {
 	}
 
 	if s.isRconResponsePacket(buf) {
-		log.Debugf("Response: %s", string(buf[10:]))
+		if s.isBadRconResponse(buf) {
+			log.Infof("Response: Bad rcon from %s", s.caddr.IP)
+		} else {
+			log.Debugf("Response: %s", string(buf[10:]))
+		}
 	}
 
 	return nil
@@ -85,8 +90,8 @@ func (s *session) proxyTo(buf []byte) error {
 	}
 
 	if s.isRconRequestPacket(buf) {
-		parts := strings.Split(string(buf), " ")
+		parts := strings.SplitN(string(buf), " ", 3)
-		log.Infof("From [%s] To [%s] Command: %s", s.caddr.IP, s.serverConn.RemoteAddr(), strings.Join(parts[2:], " "))
+		log.Infof("From [%s] To [%s] Command: %s", s.caddr.IP, s.serverConn.RemoteAddr(), parts[len(parts)-1])
 	}
 
 	return nil

pkg/udpproxy/validator.go

@@ -1,14 +1,35 @@
 package udpproxy
 
+import "bytes"
+
 type validator struct {
+	rconRequestHeader       []byte
+	getstatusRequestHeader  []byte
+	getinfoRequestHeader    []byte
+	rconResponseHeader      []byte
+	getstatusResponseHeader []byte
+	getinfoResponseHeader   []byte
+	badRconIdentifier       []byte
+}
+
+func newValidator() validator {
+	return validator{
+		rconRequestHeader:       []byte("\xff\xff\xff\xffrcon"),
+		getstatusRequestHeader:  []byte("\xff\xff\xff\xffgetstatus"),
+		getinfoRequestHeader:    []byte("\xff\xff\xff\xffgetinfo"),
+		rconResponseHeader:      []byte("\xff\xff\xff\xffprint\n"),
+		getstatusResponseHeader: []byte("\xff\xff\xff\xffstatusResponse\n"),
+		getinfoResponseHeader:   []byte("\xff\xff\xff\xffinfoResponse\n"),
+		badRconIdentifier:       []byte("Bad rcon"),
+	}
 }
 
 func (v *validator) isRconRequestPacket(buf []byte) bool {
-	return string(buf[:8]) == "\xff\xff\xff\xffrcon"
+	return bytes.Equal(buf[:len(v.rconRequestHeader)], v.rconRequestHeader)
 }
 
 func (v *validator) isQueryRequestPacket(buf []byte) bool {
-	return string(buf[:13]) == "\xff\xff\xff\xffgetstatus" || string(buf[:11]) == "\xff\xff\xff\xffgetinfo"
+	return bytes.Equal(buf[:len(v.getstatusRequestHeader)], v.getstatusRequestHeader) || bytes.Equal(buf[:len(v.getinfoRequestHeader)], v.getinfoRequestHeader)
 }
 
 func (v *validator) isValidRequestPacket(buf []byte) bool {
@@ -16,13 +37,17 @@ func (v *validator) isValidRequestPacket(buf []byte) bool {
 }
 
 func (v *validator) isRconResponsePacket(buf []byte) bool {
-	return string(buf[:9]) == "\xff\xff\xff\xffprint"
+	return bytes.Equal(buf[:len(v.rconResponseHeader)], v.rconResponseHeader)
 }
 
 func (v *validator) isQueryResponsePacket(buf []byte) bool {
-	return string(buf[:18]) == "\xff\xff\xff\xffstatusResponse" || string(buf[:16]) == "\xff\xff\xff\xffinfoResponse"
+	return bytes.Equal(buf[:len(v.getstatusResponseHeader)], v.getstatusResponseHeader) || bytes.Equal(buf[:len(v.getinfoResponseHeader)], v.getinfoResponseHeader)
 }
 
 func (v *validator) isValidResponsePacket(buf []byte) bool {
 	return v.isRconResponsePacket(buf) || v.isQueryResponsePacket(buf)
 }
+
+func (v *validator) isBadRconResponse(buf []byte) bool {
+	return bytes.Equal(buf[len(v.rconResponseHeader):len(v.rconResponseHeader)+len(v.badRconIdentifier)], v.badRconIdentifier)
+}