mirror of
https://github.com/netbirdio/netbird.git
synced 2024-11-07 16:54:16 +01:00
140 lines
3.1 KiB
Go
140 lines
3.1 KiB
Go
package dns
|
|
|
|
import (
|
|
"fmt"
|
|
"math/big"
|
|
"net"
|
|
"sync"
|
|
|
|
"github.com/google/gopacket"
|
|
"github.com/google/gopacket/layers"
|
|
"github.com/miekg/dns"
|
|
log "github.com/sirupsen/logrus"
|
|
)
|
|
|
|
type serviceViaMemory struct {
|
|
wgInterface WGIface
|
|
dnsMux *dns.ServeMux
|
|
runtimeIP string
|
|
runtimePort int
|
|
udpFilterHookID string
|
|
listenerIsRunning bool
|
|
listenerFlagLock sync.Mutex
|
|
}
|
|
|
|
func newServiceViaMemory(wgIface WGIface) *serviceViaMemory {
|
|
s := &serviceViaMemory{
|
|
wgInterface: wgIface,
|
|
dnsMux: dns.NewServeMux(),
|
|
|
|
runtimeIP: getLastIPFromNetwork(wgIface.Address().Network, 1),
|
|
runtimePort: defaultPort,
|
|
}
|
|
return s
|
|
}
|
|
|
|
func (s *serviceViaMemory) Listen() error {
|
|
s.listenerFlagLock.Lock()
|
|
defer s.listenerFlagLock.Unlock()
|
|
|
|
if s.listenerIsRunning {
|
|
return nil
|
|
}
|
|
|
|
var err error
|
|
s.udpFilterHookID, err = s.filterDNSTraffic()
|
|
if err != nil {
|
|
return fmt.Errorf("filter dns traffice: %w", err)
|
|
}
|
|
s.listenerIsRunning = true
|
|
|
|
log.Debugf("dns service listening on: %s", s.RuntimeIP())
|
|
return nil
|
|
}
|
|
|
|
func (s *serviceViaMemory) Stop() {
|
|
s.listenerFlagLock.Lock()
|
|
defer s.listenerFlagLock.Unlock()
|
|
|
|
if !s.listenerIsRunning {
|
|
return
|
|
}
|
|
|
|
if err := s.wgInterface.GetFilter().RemovePacketHook(s.udpFilterHookID); err != nil {
|
|
log.Errorf("unable to remove DNS packet hook: %s", err)
|
|
}
|
|
|
|
s.listenerIsRunning = false
|
|
}
|
|
|
|
func (s *serviceViaMemory) RegisterMux(pattern string, handler dns.Handler) {
|
|
s.dnsMux.Handle(pattern, handler)
|
|
}
|
|
|
|
func (s *serviceViaMemory) DeregisterMux(pattern string) {
|
|
s.dnsMux.HandleRemove(pattern)
|
|
}
|
|
|
|
func (s *serviceViaMemory) RuntimePort() int {
|
|
return s.runtimePort
|
|
}
|
|
|
|
func (s *serviceViaMemory) RuntimeIP() string {
|
|
return s.runtimeIP
|
|
}
|
|
|
|
func (s *serviceViaMemory) filterDNSTraffic() (string, error) {
|
|
filter := s.wgInterface.GetFilter()
|
|
if filter == nil {
|
|
return "", fmt.Errorf("can't set DNS filter, filter not initialized")
|
|
}
|
|
|
|
firstLayerDecoder := layers.LayerTypeIPv4
|
|
if s.wgInterface.Address().Network.IP.To4() == nil {
|
|
firstLayerDecoder = layers.LayerTypeIPv6
|
|
}
|
|
|
|
hook := func(packetData []byte) bool {
|
|
// Decode the packet
|
|
packet := gopacket.NewPacket(packetData, firstLayerDecoder, gopacket.Default)
|
|
|
|
// Get the UDP layer
|
|
udpLayer := packet.Layer(layers.LayerTypeUDP)
|
|
udp := udpLayer.(*layers.UDP)
|
|
|
|
msg := new(dns.Msg)
|
|
if err := msg.Unpack(udp.Payload); err != nil {
|
|
log.Tracef("parse DNS request: %v", err)
|
|
return true
|
|
}
|
|
|
|
writer := responseWriter{
|
|
packet: packet,
|
|
device: s.wgInterface.GetDevice().Device,
|
|
}
|
|
go s.dnsMux.ServeDNS(&writer, msg)
|
|
return true
|
|
}
|
|
|
|
return filter.AddUDPPacketHook(false, net.ParseIP(s.runtimeIP), uint16(s.runtimePort), hook), nil
|
|
}
|
|
|
|
func getLastIPFromNetwork(network *net.IPNet, fromEnd int) string {
|
|
// Calculate the last IP in the CIDR range
|
|
var endIP net.IP
|
|
for i := 0; i < len(network.IP); i++ {
|
|
endIP = append(endIP, network.IP[i]|^network.Mask[i])
|
|
}
|
|
|
|
// convert to big.Int
|
|
endInt := big.NewInt(0)
|
|
endInt.SetBytes(endIP)
|
|
|
|
// subtract fromEnd from the last ip
|
|
fromEndBig := big.NewInt(int64(fromEnd))
|
|
resultInt := big.NewInt(0)
|
|
resultInt.Sub(endInt, fromEndBig)
|
|
|
|
return net.IP(resultInt.Bytes()).String()
|
|
}
|