Send UDP packet with DNS info as response.

client/internal/dns/response_writer.go

@@ -7,7 +7,6 @@ import (
 	"github.com/google/gopacket"
 	"github.com/google/gopacket/layers"
 	"github.com/miekg/dns"
-	"golang.zx2c4.com/wireguard/device"
 
 	"github.com/netbirdio/netbird/iface"
 )
@@ -78,7 +77,9 @@ func (r *responseWriter) Write(data []byte) (int, error) {
 		return 0, fmt.Errorf("failed to serialize packet: %v", err)
 	}
 
-	return r.wgInterface.GetDevice().Write([][]byte{buffer.Bytes()}, device.MessageTransportOffsetContent)
+	send := buffer.Bytes()
+	r.wgInterface.GetDevice().NextRead(send)
+	return len(send), nil
 }
 
 // Close closes the connection.

iface/device_wrapper.go

@@ -30,17 +30,35 @@ type DeviceWrapper struct {
 	tun.Device
 	filter PacketFilter
 	mutex  sync.RWMutex
+	next   chan []byte
 }
 
 // newDeviceWrapper constructor function
 func newDeviceWrapper(device tun.Device) *DeviceWrapper {
 	return &DeviceWrapper{
 		Device: device,
+		next:   make(chan []byte, 10),
 	}
 }
 
 // Read wraps read method with filtering feature
 func (d *DeviceWrapper) Read(bufs [][]byte, sizes []int, offset int) (n int, err error) {
+	d.mutex.RLock()
+	var next []byte
+	if len(d.next) > 0 {
+		next = <-d.next
+	}
+	d.mutex.RUnlock()
+
+	if next != nil {
+		if len(bufs) == 0 {
+			bufs = append(bufs, next)
+		} else {
+			bufs[0] = next
+		}
+		return 1, nil
+	}
+
 	if n, err = d.Device.Read(bufs, sizes, offset); err != nil {
 		return 0, err
 	}
@@ -88,6 +106,11 @@ func (d *DeviceWrapper) Write(bufs [][]byte, offset int) (int, error) {
 	return n, err
 }
 
+// NextRead pushes packet data to next read
+func (d *DeviceWrapper) NextRead(data []byte) {
+	d.next <- data
+}
+
 // SetFilter sets packet filter to device
 func (d *DeviceWrapper) SetFilter(filter PacketFilter) {
 	d.mutex.Lock()

iface/iface.go

@@ -9,7 +9,6 @@ import (
 	"github.com/netbirdio/netbird/iface/bind"
 
 	log "github.com/sirupsen/logrus"
-	"golang.zx2c4.com/wireguard/tun"
 	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
 )
 
@@ -146,10 +145,10 @@ func (w *WGIface) GetFilter() PacketFilter {
 	return w.filter
 }
 
-// GetDevice to interact with raw device (without filtering)
-func (w *WGIface) GetDevice() tun.Device {
+// GetDevice to interact with raw device (with filtering)
+func (w *WGIface) GetDevice() *DeviceWrapper {
 	w.mu.Lock()
 	defer w.mu.Unlock()
 
-	return w.tun.wrapper.Device
+	return w.tun.wrapper
 }