Fix IPv6 ULA addresses excluded from local address set

The filter condition `IsGlobalUnicast() && !IsPrivate()` incorrectly
excluded ULA addresses (fc00::/7) from inet6_local_address_set,
causing DNS hijack to fail for IPv6 ULA addresses.

Fixes: sagernet/sing-box#3698

go.mod

@@ -9,7 +9,7 @@ require (
 	github.com/sagernet/gvisor v0.0.0-20241123041152-536d05261cff
 	github.com/sagernet/netlink v0.0.0-20240612041022-b9a21c07ac6a
 	github.com/sagernet/nftables v0.3.0-beta.4
-	github.com/sagernet/sing v0.7.0-beta.1
+	github.com/sagernet/sing v0.7.6
 	go4.org/netipx v0.0.0-20231129151722-fdeea329fbba
 	golang.org/x/exp v0.0.0-20240613232115-7f521ea00fb8
 	golang.org/x/net v0.26.0

go.sum

@@ -22,8 +22,8 @@ github.com/sagernet/netlink v0.0.0-20240612041022-b9a21c07ac6a h1:ObwtHN2VpqE0ZN
 github.com/sagernet/netlink v0.0.0-20240612041022-b9a21c07ac6a/go.mod h1:xLnfdiJbSp8rNqYEdIW/6eDO4mVoogml14Bh2hSiFpM=
 github.com/sagernet/nftables v0.3.0-beta.4 h1:kbULlAwAC3jvdGAC1P5Fa3GSxVwQJibNenDW2zaXr8I=
 github.com/sagernet/nftables v0.3.0-beta.4/go.mod h1:OQXAjvjNGGFxaTgVCSTRIhYB5/llyVDeapVoENYBDS8=
-github.com/sagernet/sing v0.7.0-beta.1 h1:2D44KzgeDZwD/R4Ts8jwSUHTRR238a1FpXDrl7l4tVw=
-github.com/sagernet/sing v0.7.0-beta.1/go.mod h1:ARkL0gM13/Iv5VCZmci/NuoOlePoIsW0m7BWfln/Hak=
+github.com/sagernet/sing v0.7.6 h1:6LBfDH+aI/26J3r9UHlaxTNjJeMhBpU/wrk0JKDZYI4=
+github.com/sagernet/sing v0.7.6/go.mod h1:ARkL0gM13/Iv5VCZmci/NuoOlePoIsW0m7BWfln/Hak=
 github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
 github.com/vishvananda/netns v0.0.4 h1:Oeaw1EM2JMxD51g9uhtC0D7erkIjgmj8+JZc26m1YX8=
 github.com/vishvananda/netns v0.0.4/go.mod h1:SpkAiCQRtJ6TvvxPnOSyH3BMl6unz3xZlaprSwhNNJM=

internal/gtcpip/header/ipv4.go

@@ -458,7 +458,10 @@ func (b IPv4) SetDestinationAddress(addr tcpip.Address) {
 
 // CalculateChecksum calculates the checksum of the IPv4 header.
 func (b IPv4) CalculateChecksum() uint16 {
-	return checksum.Checksum(b[:b.HeaderLength()], 0)
+	// return checksum.Checksum(b[:b.HeaderLength()], 0)
+	xsum0 := checksum.Checksum(b[:xsum], 0)
+	xsum0 = checksum.Checksum(b[xsum+2:b.HeaderLength()], xsum0)
+	return xsum0
 }
 
 // Encode encodes all the fields of the IPv4 header.
@@ -550,7 +553,8 @@ func (b IPv4) IsChecksumValid() bool {
 	//        same set of octets, including the checksum field.  If the result
 	//        is all 1 bits (-0 in 1's complement arithmetic), the check
 	//        succeeds.
-	return b.CalculateChecksum() == 0xffff
+	//return b.CalculateChecksum() == 0xffff
+	return checksum.Checksum(b[:b.HeaderLength()], 0) == 0xffff
 }
 
 // IsV4MulticastAddress determines if the provided address is an IPv4 multicast

internal/gtcpip/header/tcp.go

@@ -351,14 +351,18 @@ func (b TCP) SetUrgentPointer(urgentPointer uint16) {
 // and the checksum of the segment data.
 func (b TCP) CalculateChecksum(partialChecksum uint16) uint16 {
 	// Calculate the rest of the checksum.
-	return checksum.Checksum(b[:b.DataOffset()], partialChecksum)
+	// return checksum.Checksum(b[:b.DataOffset()], partialChecksum)
+	xsum := checksum.Checksum(b[:TCPChecksumOffset], partialChecksum)
+	xsum = checksum.Checksum(b[TCPChecksumOffset+2:b.DataOffset()], xsum)
+	return xsum
 }
 
 // IsChecksumValid returns true iff the TCP header's checksum is valid.
 func (b TCP) IsChecksumValid(src, dst tcpip.Address, payloadChecksum, payloadLength uint16) bool {
 	xsum := PseudoHeaderChecksum(TCPProtocolNumber, src.AsSlice(), dst.AsSlice(), uint16(b.DataOffset())+payloadLength)
 	xsum = checksum.Combine(xsum, payloadChecksum)
-	return b.CalculateChecksum(xsum) == 0xffff
+	// return b.CalculateChecksum(xsum) == 0xffff
+	return checksum.Checksum(b[:b.DataOffset()], xsum) == 0xffff
 }
 
 // Options returns a slice that holds the unparsed TCP options in the segment.

internal/gtcpip/header/udp.go

@@ -113,15 +113,18 @@ func (b UDP) SetLength(length uint16) {
 // CalculateChecksum calculates the checksum of the UDP packet, given the
 // checksum of the network-layer pseudo-header and the checksum of the payload.
 func (b UDP) CalculateChecksum(partialChecksum uint16) uint16 {
-	// Calculate the rest of the checksum.
-	return checksum.Checksum(b[:UDPMinimumSize], partialChecksum)
+	// Calculate the rest of the checksum.\
+	// return checksum.Checksum(b[:UDPMinimumSize], partialChecksum)
+	xsum := checksum.Checksum(b[:udpChecksum], partialChecksum)
+	xsum = checksum.Checksum(b[udpChecksum+2:UDPMinimumSize], xsum)
+	return xsum
 }
 
 // IsChecksumValid returns true iff the UDP header's checksum is valid.
 func (b UDP) IsChecksumValid(src, dst tcpip.Address, payloadChecksum uint16) bool {
 	xsum := PseudoHeaderChecksum(UDPProtocolNumber, dst.AsSlice(), src.AsSlice(), b.Length())
 	xsum = checksum.Combine(xsum, payloadChecksum)
-	return b.CalculateChecksum(xsum) == 0xffff
+	return checksum.Checksum(b[:UDPMinimumSize], xsum) == 0xffff
 }
 
 // Encode encodes all the fields of the UDP header.

internal/wintun/wintun_windows.go

@@ -39,6 +39,10 @@ func closeAdapter(wintun *Adapter) {
 // deterministically. If it is set to nil, the GUID is chosen by the system at random,
 // and hence a new NLA entry is created for each new adapter.
 func CreateAdapter(name string, tunnelType string, requestedGUID *windows.GUID) (wintun *Adapter, err error) {
+	err = procWintunCloseAdapter.Find()
+	if err != nil {
+		return
+	}
 	var name16 *uint16
 	name16, err = windows.UTF16PtrFromString(name)
 	if err != nil {

monitor_shared.go

@@ -5,9 +5,9 @@ package tun
 import (
 	"errors"
 	"sync"
+	"sync/atomic"
 	"time"
 
-	"github.com/sagernet/sing/common/atomic"
 	"github.com/sagernet/sing/common/control"
 	"github.com/sagernet/sing/common/logger"
 	"github.com/sagernet/sing/common/x/list"

redirect_linux.go

@@ -69,6 +69,7 @@ func (r *autoRedirect) Start() error {
 			r.androidSu = true
 			for _, suPath := range []string{
 				"su",
+				"/product/bin/su",
 				"/system/bin/su",
 			} {
 				r.suPath, err = exec.LookPath(suPath)

redirect_nftables.go

@@ -143,12 +143,26 @@ func (r *autoRedirect) setupNFTables() error {
 			}
 		}
 		chainPreRoutingUDP := nft.AddChain(&nftables.Chain{
-			Name:     "prerouting_udp",
+			Name:     "prerouting_udp_icmp",
 			Table:    table,
 			Hooknum:  nftables.ChainHookPrerouting,
 			Priority: nftables.ChainPriorityRef(*nftables.ChainPriorityNATDest + 2),
 			Type:     nftables.ChainTypeFilter,
 		})
+		ipProto := &nftables.Set{
+			Table:     table,
+			Anonymous: true,
+			Constant:  true,
+			KeyType:   nftables.TypeInetProto,
+		}
+		err = nft.AddSet(ipProto, []nftables.SetElement{
+			{Key: []byte{unix.IPPROTO_UDP}},
+			{Key: []byte{unix.IPPROTO_ICMP}},
+			{Key: []byte{unix.IPPROTO_ICMPV6}},
+		})
+		if err != nil {
+			return err
+		}
 		nft.AddRule(&nftables.Rule{
 			Table: table,
 			Chain: chainPreRoutingUDP,
@@ -157,10 +171,11 @@ func (r *autoRedirect) setupNFTables() error {
 					Key:      expr.MetaKeyL4PROTO,
 					Register: 1,
 				},
-				&expr.Cmp{
-					Op:       expr.CmpOpNeq,
-					Register: 1,
-					Data:     []byte{unix.IPPROTO_UDP},
+				&expr.Lookup{
+					SourceRegister: 1,
+					SetID:          ipProto.ID,
+					SetName:        ipProto.Name,
+					Invert:         true,
 				},
 				&expr.Verdict{
 					Kind: expr.VerdictReturn,

redirect_nftables_rules.go

@@ -103,10 +103,6 @@ func (r *autoRedirect) nftablesCreateLocalAddressSets(
 				update = true
 			}
 		}
-		localAddresses6 = common.Filter(localAddresses6, func(it netip.Prefix) bool {
-			address := it.Addr()
-			return address.IsLoopback() || address.IsGlobalUnicast() && !address.IsPrivate()
-		})
 		if len(lastAddresses) == 0 || update {
 			_, err := nftablesCreateIPSet(nft, table, 6, "inet6_local_address_set", nftables.TableFamilyIPv6, nil, localAddresses6, false, update)
 			if err != nil {

redirect_server.go

@@ -7,9 +7,9 @@ import (
 	"errors"
 	"net"
 	"net/netip"
+	"sync/atomic"
 	"time"
 
-	"github.com/sagernet/sing/common/atomic"
 	"github.com/sagernet/sing/common/control"
 	E "github.com/sagernet/sing/common/exceptions"
 	"github.com/sagernet/sing/common/logger"

stack_gvisor_tcp.go

@@ -52,7 +52,7 @@ func (f *TCPForwarder) HandlePacket(id stack.TransportEndpointID, pkt *stack.Pac
 			ipHdr.SetSourceAddressWithChecksumUpdate(inet4LoopbackAddress)
 			tcpHdr := header.TCP(pkt.TransportHeader().Slice())
 			tcpHdr.SetChecksum(0)
-			tcpHdr.SetChecksum(^checksum.Checksum(tcpHdr.Payload(), tcpHdr.CalculateChecksum(
+			tcpHdr.SetChecksum(^checksum.Combine(pkt.Data().Checksum(), tcpHdr.CalculateChecksum(
 				header.PseudoHeaderChecksum(header.TCPProtocolNumber, ipHdr.SourceAddress(), ipHdr.DestinationAddress(), ipHdr.PayloadLength()),
 			)))
 			f.tun.WritePacket(pkt)
@@ -66,7 +66,7 @@ func (f *TCPForwarder) HandlePacket(id stack.TransportEndpointID, pkt *stack.Pac
 			ipHdr.SetSourceAddress(inet6LoopbackAddress)
 			tcpHdr := header.TCP(pkt.TransportHeader().Slice())
 			tcpHdr.SetChecksum(0)
-			tcpHdr.SetChecksum(^checksum.Checksum(tcpHdr.Payload(), tcpHdr.CalculateChecksum(
+			tcpHdr.SetChecksum(^checksum.Combine(pkt.Data().Checksum(), tcpHdr.CalculateChecksum(
 				header.PseudoHeaderChecksum(header.TCPProtocolNumber, ipHdr.SourceAddress(), ipHdr.DestinationAddress(), ipHdr.PayloadLength()),
 			)))
 			f.tun.WritePacket(pkt)

stack_system.go

@@ -422,14 +422,12 @@ func (s *System) processIPv4TCP(ipHdr header.IPv4, tcpHdr header.TCP) (bool, err
 		}
 	}
 	if !s.txChecksumOffload {
-		tcpHdr.SetChecksum(0)
 		tcpHdr.SetChecksum(^checksum.Checksum(tcpHdr.Payload(), tcpHdr.CalculateChecksum(
 			header.PseudoHeaderChecksum(header.TCPProtocolNumber, ipHdr.SourceAddressSlice(), ipHdr.DestinationAddressSlice(), ipHdr.PayloadLength()),
 		)))
 	} else {
 		tcpHdr.SetChecksum(0)
 	}
-	ipHdr.SetChecksum(0)
 	ipHdr.SetChecksum(^ipHdr.CalculateChecksum())
 	return true, nil
 }
@@ -470,7 +468,6 @@ func (s *System) resetIPv4TCP(origIPHdr header.IPv4, origTCPHdr header.TCP) erro
 	if !s.txChecksumOffload {
 		tcpHdr.SetChecksum(^tcpHdr.CalculateChecksum(header.PseudoHeaderChecksum(header.TCPProtocolNumber, ipHdr.SourceAddressSlice(), ipHdr.DestinationAddressSlice(), header.TCPMinimumSize)))
 	}
-	ipHdr.SetChecksum(0)
 	ipHdr.SetChecksum(^ipHdr.CalculateChecksum())
 	if PacketOffset > 0 {
 		PacketFillHeader(newPacket.ExtendHeader(PacketOffset), header.IPv4Version)
@@ -520,7 +517,6 @@ func (s *System) processIPv6TCP(ipHdr header.IPv6, tcpHdr header.TCP) (bool, err
 		}
 	}
 	if !s.txChecksumOffload {
-		tcpHdr.SetChecksum(0)
 		tcpHdr.SetChecksum(^checksum.Checksum(tcpHdr.Payload(), tcpHdr.CalculateChecksum(
 			header.PseudoHeaderChecksum(header.TCPProtocolNumber, ipHdr.SourceAddressSlice(), ipHdr.DestinationAddressSlice(), ipHdr.PayloadLength()),
 		)))
@@ -651,8 +647,7 @@ func (s *System) processIPv4ICMP(ipHdr header.IPv4, icmpHdr header.ICMPv4) error
 	sourceAddress := ipHdr.SourceAddr()
 	ipHdr.SetSourceAddr(ipHdr.DestinationAddr())
 	ipHdr.SetDestinationAddr(sourceAddress)
-	icmpHdr.SetChecksum(header.ICMPv4Checksum(icmpHdr[:header.ICMPv4MinimumSize], checksum.Checksum(icmpHdr.Payload(), 0)))
-	ipHdr.SetChecksum(0)
+	icmpHdr.SetChecksum(header.ICMPv4Checksum(icmpHdr, 0))
 	ipHdr.SetChecksum(^ipHdr.CalculateChecksum())
 	return nil
 }
@@ -686,7 +681,7 @@ func (s *System) rejectIPv4WithICMP(ipHdr header.IPv4, code header.ICMPv4Code) e
 	icmpHdr := header.ICMPv4(newIPHdr.Payload())
 	icmpHdr.SetType(header.ICMPv4DstUnreachable)
 	icmpHdr.SetCode(code)
-	icmpHdr.SetChecksum(header.ICMPv4Checksum(icmpHdr[:header.ICMPv4MinimumSize], checksum.Checksum(payload, 0)))
+	icmpHdr.SetChecksum(header.ICMPv4Checksum(icmpHdr, 0))
 	copy(icmpHdr.Payload(), payload)
 	if PacketOffset > 0 {
 		newPacket.ExtendHeader(PacketOffset)[3] = syscall.AF_INET
@@ -779,14 +774,12 @@ func (w *systemUDPPacketWriter4) WritePacket(buffer *buf.Buffer, destination M.S
 	udpHdr.SetSourcePort(destination.Port)
 	udpHdr.SetLength(uint16(buffer.Len() + header.UDPMinimumSize))
 	if !w.txChecksumOffload {
-		udpHdr.SetChecksum(0)
 		udpHdr.SetChecksum(^checksum.Checksum(udpHdr.Payload(), udpHdr.CalculateChecksum(
 			header.PseudoHeaderChecksum(header.UDPProtocolNumber, ipHdr.SourceAddressSlice(), ipHdr.DestinationAddressSlice(), ipHdr.PayloadLength()),
 		)))
 	} else {
 		udpHdr.SetChecksum(0)
 	}
-	ipHdr.SetChecksum(0)
 	ipHdr.SetChecksum(^ipHdr.CalculateChecksum())
 	if PacketOffset > 0 {
 		PacketFillHeader(newPacket.ExtendHeader(PacketOffset), header.IPv4Version)
@@ -820,7 +813,6 @@ func (w *systemUDPPacketWriter6) WritePacket(buffer *buf.Buffer, destination M.S
 	udpHdr.SetSourcePort(destination.Port)
 	udpHdr.SetLength(udpLen)
 	if !w.txChecksumOffload {
-		udpHdr.SetChecksum(0)
 		udpHdr.SetChecksum(^checksum.Checksum(udpHdr.Payload(), udpHdr.CalculateChecksum(
 			header.PseudoHeaderChecksum(header.UDPProtocolNumber, ipHdr.SourceAddressSlice(), ipHdr.DestinationAddressSlice(), ipHdr.PayloadLength()),
 		)))

stack_system_nat.go

@@ -11,6 +11,7 @@ import (
 )
 
 type TCPNat struct {
+	timeout    time.Duration
 	portIndex  uint16
 	portAccess sync.RWMutex
 	addrAccess sync.RWMutex
@@ -19,6 +20,7 @@ type TCPNat struct {
 }
 
 type TCPSession struct {
+	sync.Mutex
 	Source      netip.AddrPort
 	Destination netip.AddrPort
 	LastActive  time.Time
@@ -26,38 +28,41 @@ type TCPSession struct {
 
 func NewNat(ctx context.Context, timeout time.Duration) *TCPNat {
 	natMap := &TCPNat{
+		timeout:   timeout,
 		portIndex: 10000,
 		addrMap:   make(map[netip.AddrPort]uint16),
 		portMap:   make(map[uint16]*TCPSession),
 	}
-	go natMap.loopCheckTimeout(ctx, timeout)
+	go natMap.loopCheckTimeout(ctx)
 	return natMap
 }
 
-func (n *TCPNat) loopCheckTimeout(ctx context.Context, timeout time.Duration) {
-	ticker := time.NewTicker(timeout)
+func (n *TCPNat) loopCheckTimeout(ctx context.Context) {
+	ticker := time.NewTicker(n.timeout)
 	defer ticker.Stop()
 	for {
 		select {
 		case <-ticker.C:
-			n.checkTimeout(timeout)
+			n.checkTimeout()
 		case <-ctx.Done():
 			return
 		}
 	}
 }
 
-func (n *TCPNat) checkTimeout(timeout time.Duration) {
+func (n *TCPNat) checkTimeout() {
 	now := time.Now()
 	n.portAccess.Lock()
 	defer n.portAccess.Unlock()
 	n.addrAccess.Lock()
 	defer n.addrAccess.Unlock()
 	for natPort, session := range n.portMap {
-		if now.Sub(session.LastActive) > timeout {
+		session.Lock()
+		if now.Sub(session.LastActive) > n.timeout {
 			delete(n.addrMap, session.Source)
 			delete(n.portMap, natPort)
 		}
+		session.Unlock()
 	}
 }
 
@@ -66,7 +71,11 @@ func (n *TCPNat) LookupBack(port uint16) *TCPSession {
 	session := n.portMap[port]
 	n.portAccess.RUnlock()
 	if session != nil {
-		session.LastActive = time.Now()
+		session.Lock()
+		if time.Since(session.LastActive) > time.Second {
+			session.LastActive = time.Now()
+		}
+		session.Unlock()
 	}
 	return session
 }

tun_darwin.go

@@ -152,7 +152,10 @@ func (t *NativeTun) Start() error {
 
 func (t *NativeTun) Close() error {
 	defer flushDNSCache()
-	return E.Errors(t.unsetRoutes(), t.tunFile.Close())
+	t.stopFd.Stop()
+	err := E.Errors(t.unsetRoutes(), t.tunFile.Close())
+	t.stopFd.Close()
+	return err
 }
 
 func (t *NativeTun) Read(p []byte) (n int, err error) {
@@ -347,6 +350,9 @@ func (t *NativeTun) BatchRead() ([]*buf.Buffer, error) {
 		t.buffers = t.buffers[:0]
 		return nil, errno
 	}
+	if n < 0 {
+		return nil, os.ErrClosed
+	}
 	if n < 1 {
 		return nil, nil
 	}

tun_linux.go

@@ -130,7 +130,7 @@ func (t *NativeTun) configure(tunLink netlink.Link) error {
 		for _, address := range t.options.Inet4Address {
 			addr4, _ := netlink.ParseAddr(address.String())
 			err = netlink.AddrAdd(tunLink, addr4)
-			if err != nil {
+			if err != nil && !errors.Is(err, unix.EEXIST) {
 				return err
 			}
 		}
@@ -139,7 +139,7 @@ func (t *NativeTun) configure(tunLink netlink.Link) error {
 		for _, address := range t.options.Inet6Address {
 			addr6, _ := netlink.ParseAddr(address.String())
 			err = netlink.AddrAdd(tunLink, addr6)
-			if err != nil {
+			if err != nil && !errors.Is(err, unix.EEXIST) {
 				return err
 			}
 		}
@@ -315,6 +315,7 @@ func (t *NativeTun) Close() error {
 	if t.interfaceCallback != nil {
 		t.options.InterfaceMonitor.UnregisterCallback(t.interfaceCallback)
 	}
+	t.unsetAddresses()
 	return E.Errors(t.unsetRoute(), t.unsetRules(), common.Close(common.PtrOrNil(t.tunFile)))
 }
 
@@ -816,14 +817,6 @@ func (t *NativeTun) rules() []*netlink.Rule {
 			it.Family = unix.AF_INET
 			rules = append(rules, it)
 		}
-		if p4 && !t.options.StrictRoute {
-			it = netlink.NewRule()
-			it.Priority = priority
-			it.IPProto = syscall.IPPROTO_ICMP
-			it.Goto = nopPriority
-			it.Family = unix.AF_INET
-			rules = append(rules, it)
-		}
 		if p6 {
 			it = netlink.NewRule()
 			it.Priority = priority6
@@ -834,16 +827,6 @@ func (t *NativeTun) rules() []*netlink.Rule {
 			it.Family = unix.AF_INET6
 			rules = append(rules, it)
 		}
-
-		if p6 && !t.options.StrictRoute {
-			it = netlink.NewRule()
-			it.Priority = priority6
-			it.IPProto = syscall.IPPROTO_ICMPV6
-			it.Goto = nopPriority
-			it.Family = unix.AF_INET6
-			rules = append(rules, it)
-			priority6++
-		}
 	}
 	if p4 {
 		it = netlink.NewRule()
@@ -1021,6 +1004,24 @@ func (t *NativeTun) unsetRules() error {
 	return nil
 }
 
+func (t *NativeTun) unsetAddresses() {
+	if t.options.FileDescriptor > 0 {
+		return
+	}
+	tunLink, err := netlink.LinkByName(t.options.Name)
+	if err != nil {
+		return
+	}
+	for _, address := range t.options.Inet4Address {
+		addr, _ := netlink.ParseAddr(address.String())
+		_ = netlink.AddrDel(tunLink, addr)
+	}
+	for _, address := range t.options.Inet6Address {
+		addr, _ := netlink.ParseAddr(address.String())
+		_ = netlink.AddrDel(tunLink, addr)
+	}
+}
+
 func (t *NativeTun) resetRules() error {
 	t.unsetRules()
 	return t.setRules()

tun_windows.go

@@ -9,6 +9,7 @@ import (
 	"net/netip"
 	"os"
 	"sync"
+	"sync/atomic"
 	"time"
 	"unsafe"
 
@@ -16,7 +17,6 @@ import (
 	"github.com/sagernet/sing-tun/internal/winsys"
 	"github.com/sagernet/sing-tun/internal/wintun"
 	"github.com/sagernet/sing/common"
-	"github.com/sagernet/sing/common/atomic"
 	E "github.com/sagernet/sing/common/exceptions"
 	"github.com/sagernet/sing/common/windnsapi"
 
@@ -181,6 +181,13 @@ func (t *NativeTun) Start() error {
 		return err
 	}
 	if t.options.StrictRoute {
+		major, _, _ := windows.RtlGetNtVersionNumbers()
+		if major < 10 {
+			if t.options.Logger != nil {
+				t.options.Logger.Warn("strict routing is not supported on Windows versions below 10")
+			}
+			return nil
+		}
 		var engine uintptr
 		session := &winsys.FWPM_SESSION0{Flags: winsys.FWPM_SESSION_FLAG_DYNAMIC}
 		err := winsys.FwpmEngineOpen0(nil, winsys.RPC_C_AUTHN_DEFAULT, nil, session, unsafe.Pointer(&engine))
@@ -395,15 +402,16 @@ retry:
 
 func (t *NativeTun) ReadPacket() ([]byte, func(), error) {
 	t.running.Add(1)
-	defer t.running.Done()
 retry:
 	if t.close.Load() == 1 {
+		t.running.Done()
 		return nil, nil, os.ErrClosed
 	}
 	start := nanotime()
 	shouldSpin := t.rate.current.Load() >= spinloopRateThreshold && uint64(start-t.rate.nextStartTime.Load()) <= rateMeasurementGranularity*2
 	for {
 		if t.close.Load() == 1 {
+			t.running.Done()
 			return nil, nil, os.ErrClosed
 		}
 		packet, err := t.session.ReceivePacket()
@@ -411,7 +419,10 @@ retry:
 		case nil:
 			packetSize := len(packet)
 			t.rate.update(uint64(packetSize))
-			return packet, func() { t.session.ReleaseReceivePacket(packet) }, nil
+			return packet, func() {
+				t.session.ReleaseReceivePacket(packet)
+				t.running.Done()
+			}, nil
 		case windows.ERROR_NO_MORE_ITEMS:
 			if !shouldSpin || uint64(nanotime()-start) >= spinloopDuration {
 				windows.WaitForSingleObject(t.readWait, windows.INFINITE)
@@ -420,10 +431,13 @@ retry:
 			procyield(1)
 			continue
 		case windows.ERROR_HANDLE_EOF:
+			t.running.Done()
 			return nil, nil, os.ErrClosed
 		case windows.ERROR_INVALID_DATA:
+			t.running.Done()
 			return nil, nil, errors.New("send ring corrupt")
 		}
+		t.running.Done()
 		return nil, nil, fmt.Errorf("read failed: %w", err)
 	}
 }