refactor: never panic in rvpn_conn

client/rvpn_conn.go

@@ -18,7 +18,7 @@ type RvpnConn struct {
 	recvErrCount int
 }
 
-// always success or panic
+// try best to read, if return err!=nil, please panic
 func (r *RvpnConn) Read(p []byte) (n int, err error) {
 	r.recvLock.Lock()
 	defer r.recvLock.Unlock()
@@ -30,18 +30,17 @@ func (r *RvpnConn) Read(p []byte) (n int, err error) {
 		_ = r.recvConn.Close()
 		r.recvConn, err = r.easyConnectClient.RecvConn()
 		if err != nil {
-			// TODO graceful shutdown
-			panic(err)
+			return 0, err
 		}
 		r.recvErrCount++
 		if r.recvErrCount >= 5 {
-			panic("recv retry limit exceeded.")
+			return 0, err
 		}
 	}
 	return
 }
 
-// always success or panic
+// try best to write, if return err!=nil, please panic
 func (r *RvpnConn) Write(p []byte) (n int, err error) {
 	r.sendLock.Lock()
 	defer r.sendLock.Unlock()
@@ -52,12 +51,11 @@ func (r *RvpnConn) Write(p []byte) (n int, err error) {
 		_ = r.sendConn.Close()
 		r.sendConn, err = r.easyConnectClient.SendConn()
 		if err != nil {
-			// TODO graceful shutdown
-			panic(err)
+			return 0, err
 		}
 		r.sendErrCount++
 		if r.sendErrCount >= 5 {
-			panic("send retry limit exceeded.")
+			return 0, err
 		}
 	}
 	return
@@ -84,13 +82,13 @@ func NewRvpnConn(ec *EasyConnectClient) (*RvpnConn, error) {
 	c.sendConn, err = ec.SendConn()
 	if err != nil {
 		log.Printf("Error occurred while creating sendConn: %v", err)
-		panic(err)
+		return nil, err
 	}
 
 	c.recvConn, err = ec.RecvConn()
 	if err != nil {
 		log.Printf("Error occurred while creating recvConn: %v", err)
-		panic(err)
+		return nil, err
 	}
 	return c, nil
 }

stack/gvisor/stack.go

@@ -78,8 +78,10 @@ func (ep *Endpoint) WritePackets(list stack.PacketBufferList) (int, tcpip.Error)
 		}
 
 		if ep.rvpnConn != nil {
-			n, _ := ep.rvpnConn.Write(buf)
-
+			n, err := ep.rvpnConn.Write(buf)
+			if err != nil {
+				panic(err)
+			}
 			log.DebugPrintf("Send: wrote %d bytes", n)
 			log.DebugDumpHex(buf[:n])
 		}
@@ -139,14 +141,18 @@ func (s *Stack) SetupResolve(r zcdns.LocalServer) {
 }
 
 func (s *Stack) Run() {
-
-	s.endpoint.rvpnConn, _ = client.NewRvpnConn(s.endpoint.easyConnectClient)
-
+	var connErr error
+	s.endpoint.rvpnConn, connErr = client.NewRvpnConn(s.endpoint.easyConnectClient)
+	if connErr != nil {
+		panic(connErr)
+	}
 	// Read from VPN server and send to gVisor stack
 	for {
-		buf := make([]byte, 1500)
-		n, _ := s.endpoint.rvpnConn.Read(buf)
-
+		buf := make([]byte, MTU)
+		n, err := s.endpoint.rvpnConn.Read(buf)
+		if err != nil {
+			panic(err)
+		}
 		log.DebugPrintf("Recv: read %d bytes", n)
 		log.DebugDumpHex(buf[:n])
 

stack/tun/stack.go

@@ -26,18 +26,23 @@ func (s *Stack) SetupResolve(r zcdns.LocalServer) {
 }
 
 func (s *Stack) Run() {
-	s.rvpnConn, _ = client.NewRvpnConn(s.endpoint.easyConnectClient)
-
+	var connErr error
+	s.rvpnConn, connErr = client.NewRvpnConn(s.endpoint.easyConnectClient)
+	if connErr != nil {
+		panic(connErr)
+	}
 	// Read from VPN server and send to TUN stack
 	go func() {
 		for {
 			buf := make([]byte, MTU+tun.PacketOffset)
-			n, _ := s.rvpnConn.Read(buf)
-
+			n, err := s.rvpnConn.Read(buf)
+			if err != nil {
+				panic(err)
+			}
 			log.DebugPrintf("Recv: read %d bytes", n)
 			log.DebugDumpHex(buf[:n])
 
-			err := s.endpoint.Write(buf[:n])
+			err = s.endpoint.Write(buf[:n])
 			if err != nil {
 				log.Printf("Error occurred while writing to TUN stack: %v", err)
 				panic(err)
@@ -95,6 +100,9 @@ func (s *Stack) processIPV4TCP(packet zctcpip.IPv4Packet, tcpPacket zctcpip.TCPP
 		return s.endpoint.Write(packet)
 	}
 	n, err := s.rvpnConn.Write(packet)
+	if err != nil {
+		panic(err)
+	}
 	log.DebugPrintf("Send: wrote %d bytes", n)
 	log.DebugDumpHex(packet[:n])
 
@@ -118,6 +126,9 @@ func (s *Stack) processIPV4UDP(packet zctcpip.IPv4Packet, udpPacket zctcpip.UDPP
 	}
 
 	n, err := s.rvpnConn.Write(packet)
+	if err != nil {
+		panic(err)
+	}
 	log.DebugPrintf("Send: wrote %d bytes", n)
 	log.DebugDumpHex(packet[:n])