remove string casts

compare byte slices

pkg/udpproxy/session.go

@@ -9,24 +9,27 @@ import (
 	log "github.com/sirupsen/logrus"
 )
 
-type Session struct {
+type session struct {
 	serverConn *net.UDPConn
 	proxyConn  *net.UDPConn
 	caddr      *net.UDPAddr
 	updateTime time.Time
+
+	validator
 }
 
-func newSession(caddr *net.UDPAddr, raddr *net.UDPAddr, proxyConn *net.UDPConn) (*Session, error) {
+func newSession(caddr *net.UDPAddr, raddr *net.UDPAddr, proxyConn *net.UDPConn) (*session, error) {
 	serverConn, err := net.DialUDP("udp", nil, raddr)
 	if err != nil {
 		return nil, err
 	}
 
-	session := &Session{
+	session := &session{
 		serverConn: serverConn,
 		proxyConn:  proxyConn,
 		caddr:      caddr,
 		updateTime: time.Now(),
+		validator:  newValidator(),
 	}
 
 	go session.listen()
@@ -34,31 +37,7 @@ func newSession(caddr *net.UDPAddr, raddr *net.UDPAddr, proxyConn *net.UDPConn)
 	return session, nil
 }
 
-func (s *Session) isRconRequestPacket(buf []byte) bool {
+func (s *session) listen() error {
-	return string(buf[:8]) == "\xff\xff\xff\xffrcon"
-}
-
-func (s *Session) isQueryRequestPacket(buf []byte) bool {
-	return string(buf[:13]) == "\xff\xff\xff\xffgetstatus" || string(buf[:11]) == "\xff\xff\xff\xffgetinfo"
-}
-
-func (s *Session) isValidRequestPacket(buf []byte) bool {
-	return s.isRconRequestPacket(buf) || s.isQueryRequestPacket(buf)
-}
-
-func (s *Session) isRconResponsePacket(buf []byte) bool {
-	return string(buf[:9]) == "\xff\xff\xff\xffprint"
-}
-
-func (s *Session) isQueryResponsePacket(buf []byte) bool {
-	return string(buf[:18]) == "\xff\xff\xff\xffstatusResponse" || string(buf[:16]) == "\xff\xff\xff\xffinfoResponse"
-}
-
-func (s *Session) isValidResponsePacket(buf []byte) bool {
-	return s.isRconResponsePacket(buf) || s.isQueryResponsePacket(buf)
-}
-
-func (s *Session) listen() error {
 	for {
 		buf := make([]byte, 2048)
 		n, err := s.serverConn.Read(buf)
@@ -71,7 +50,7 @@ func (s *Session) listen() error {
 	}
 }
 
-func (s *Session) proxyFrom(buf []byte) error {
+func (s *session) proxyFrom(buf []byte) error {
 	if !s.isValidResponsePacket(buf) {
 		err := errors.New("not a rcon or query response packet")
 		log.Error(err.Error())
@@ -86,13 +65,17 @@ 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
 }
 
-func (s *Session) proxyTo(buf []byte) error {
+func (s *session) proxyTo(buf []byte) error {
 	if !s.isValidRequestPacket(buf) {
 		err := errors.New("not a rcon or query request packet")
 		log.Error(err.Error())
@@ -107,8 +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/udpproxy.go

@@ -15,7 +15,7 @@ type Client struct {
 	proxyConn *net.UDPConn
 
 	mutex    sync.RWMutex
-	sessions map[string]*Session
+	sessions map[string]*session
 }
 
 func New(port, target string) (*Client, error) {
@@ -33,7 +33,7 @@ func New(port, target string) (*Client, error) {
 		laddr:    laddr,
 		raddr:    raddr,
 		mutex:    sync.RWMutex{},
-		sessions: map[string]*Session{},
+		sessions: map[string]*session{},
 	}, nil
 }
 

pkg/udpproxy/validator.go

@@ -0,0 +1,53 @@
+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 bytes.Equal(buf[:len(v.rconRequestHeader)], v.rconRequestHeader)
+}
+
+func (v *validator) isQueryRequestPacket(buf []byte) bool {
+	return bytes.Equal(buf[:len(v.getstatusRequestHeader)], v.getstatusRequestHeader) || bytes.Equal(buf[:len(v.getinfoRequestHeader)], v.getinfoRequestHeader)
+}
+
+func (v *validator) isValidRequestPacket(buf []byte) bool {
+	return v.isRconRequestPacket(buf) || v.isQueryRequestPacket(buf)
+}
+
+func (v *validator) isRconResponsePacket(buf []byte) bool {
+	return bytes.Equal(buf[:len(v.rconResponseHeader)], v.rconResponseHeader)
+}
+
+func (v *validator) isQueryResponsePacket(buf []byte) bool {
+	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)
+}