Try the timeout

interface.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"net/netip"
+	"runtime"
 	"sync"
 	"sync/atomic"
 	"time"
@@ -258,6 +259,7 @@ func (f *Interface) run() (func(), error) {
 }
 
 func (f *Interface) listenOut(i int) {
+	runtime.LockOSThread()
 	var li udp.Conn
 	if i > 0 {
 		li = f.writers[i]

overlay/tun_linux.go

@@ -65,11 +65,6 @@ type ifreqQLEN struct {
 }
 
 func newTunFromFd(c *config.C, l *logrus.Logger, deviceFd int, vpnNetworks []netip.Prefix) (*tun, error) {
-	err := unix.SetNonblock(deviceFd, true)
-	if err != nil {
-		return nil, err
-	}
-
 	file := os.NewFile(uintptr(deviceFd), "/dev/net/tun")
 
 	t, err := newTunGeneric(c, l, file, vpnNetworks)
@@ -116,11 +111,6 @@ func newTun(c *config.C, l *logrus.Logger, vpnNetworks []netip.Prefix, multiqueu
 	}
 	name := strings.Trim(string(req.Name[:]), "\x00")
 
-	err = unix.SetNonblock(fd, true)
-	if err != nil {
-		return nil, err
-	}
-
 	file := os.NewFile(uintptr(fd), "/dev/net/tun")
 	t, err := newTunGeneric(c, l, file, vpnNetworks)
 	if err != nil {
@@ -142,12 +132,7 @@ func newTunGeneric(c *config.C, l *logrus.Logger, file *os.File, vpnNetworks []n
 		l:               l,
 	}
 
-	err := unix.SetNonblock(t.fd, true)
-	if err != nil {
-		return nil, err
-	}
-
-	err = t.reload(c, true)
+	err := t.reload(c, true)
 	if err != nil {
 		return nil, err
 	}
@@ -242,11 +227,6 @@ func (t *tun) NewMultiQueueReader() (io.ReadWriteCloser, error) {
 		return nil, err
 	}
 
-	err = unix.SetNonblock(fd, true)
-	if err != nil {
-		return nil, err
-	}
-
 	file := os.NewFile(uintptr(fd), "/dev/net/tun")
 
 	return file, nil
@@ -257,6 +237,29 @@ func (t *tun) RoutesFor(ip netip.Addr) routing.Gateways {
 	return r
 }
 
+func (t *tun) Write(b []byte) (int, error) {
+	var nn int
+	maximum := len(b)
+
+	for {
+		n, err := unix.Write(t.fd, b[nn:maximum])
+		if n > 0 {
+			nn += n
+		}
+		if nn == len(b) {
+			return nn, err
+		}
+
+		if err != nil {
+			return nn, err
+		}
+
+		if n == 0 {
+			return nn, io.ErrUnexpectedEOF
+		}
+	}
+}
+
 func (t *tun) deviceBytes() (o [16]byte) {
 	for i, c := range t.Device {
 		o[i] = byte(c)

udp/udp_linux.go

@@ -4,13 +4,12 @@
 package udp
 
 import (
-	"context"
 	"encoding/binary"
 	"fmt"
 	"net"
 	"net/netip"
-	"strconv"
 	"syscall"
+	"time"
 	"unsafe"
 
 	"github.com/rcrowley/go-metrics"
@@ -19,54 +18,58 @@ import (
 	"golang.org/x/sys/unix"
 )
 
+var readTimeout = unix.NsecToTimeval(int64(time.Millisecond * 500))
+
 type StdConn struct {
-	c     *net.UDPConn
-	rc    syscall.RawConn
+	sysFd int
 	isV4  bool
 	l     *logrus.Logger
 	batch int
-
-	// cached fields for reading packets
-	msgs    []rawMessage
-	buffers [][]byte
-	names   [][]byte
-	n       uintptr
-	err     error
 }
 
 func NewListener(l *logrus.Logger, ip netip.Addr, port int, multi bool, batch int) (Conn, error) {
-	lc := net.ListenConfig{
-		Control: func(network, address string, c syscall.RawConn) error {
+	af := unix.AF_INET6
+	if ip.Is4() {
+		af = unix.AF_INET
+	}
+	syscall.ForkLock.RLock()
+	fd, err := unix.Socket(af, unix.SOCK_DGRAM, unix.IPPROTO_UDP)
+	if err == nil {
+		unix.CloseOnExec(fd)
+	}
+	syscall.ForkLock.RUnlock()
+
+	if err != nil {
+		unix.Close(fd)
+		return nil, fmt.Errorf("unable to open socket: %s", err)
+	}
+
 	if multi {
-				var err error
-				oErr := c.Control(func(fd uintptr) {
-					err = unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_REUSEPORT, 1)
-				})
-				if oErr != nil {
-					return fmt.Errorf("error while setting SO_REUSEPORT: %w", oErr)
-				}
-				if err != nil {
-					return fmt.Errorf("unable to set SO_REUSEPORT: %w", err)
+		if err = unix.SetsockoptInt(fd, unix.SOL_SOCKET, unix.SO_REUSEPORT, 1); err != nil {
+			return nil, fmt.Errorf("unable to set SO_REUSEPORT: %s", err)
 		}
 	}
 
-			return nil
-		},
+	// Set a read timeout
+	if err = unix.SetsockoptTimeval(fd, unix.SOL_SOCKET, unix.SO_RCVTIMEO, &readTimeout); err != nil {
+		return nil, fmt.Errorf("unable to set SO_RCVTIMEO: %s", err)
 	}
 
-	c, err := lc.ListenPacket(context.Background(), "udp", net.JoinHostPort(ip.String(), strconv.Itoa(port)))
-	if err != nil {
-		return nil, fmt.Errorf("unable to open socket: %w", err)
+	var sa unix.Sockaddr
+	if ip.Is4() {
+		sa4 := &unix.SockaddrInet4{Port: port}
+		sa4.Addr = ip.As4()
+		sa = sa4
+	} else {
+		sa6 := &unix.SockaddrInet6{Port: port}
+		sa6.Addr = ip.As16()
+		sa = sa6
+	}
+	if err = unix.Bind(fd, sa); err != nil {
+		return nil, fmt.Errorf("unable to bind to socket: %s", err)
 	}
 
-	uc := c.(*net.UDPConn)
-	rc, err := uc.SyscallConn()
-	if err != nil {
-		_ = c.Close()
-		return nil, fmt.Errorf("unable to open sysfd: %w", err)
-	}
-
-	return &StdConn{c: uc, rc: rc, isV4: ip.Is4(), l: l, batch: batch}, err
+	return &StdConn{sysFd: fd, isV4: ip.Is4(), l: l, batch: batch}, err
 }
 
 func (u *StdConn) Rebind() error {
@@ -74,179 +77,181 @@ func (u *StdConn) Rebind() error {
 }
 
 func (u *StdConn) SetRecvBuffer(n int) error {
-	var err error
-	oErr := u.rc.Control(func(fd uintptr) {
-		err = unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_RCVBUFFORCE, n)
-	})
-	if oErr != nil {
-		return oErr
-	}
-	return err
+	return unix.SetsockoptInt(u.sysFd, unix.SOL_SOCKET, unix.SO_RCVBUFFORCE, n)
 }
 
 func (u *StdConn) SetSendBuffer(n int) error {
-	var err error
-	oErr := u.rc.Control(func(fd uintptr) {
-		err = unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_SNDBUFFORCE, n)
-	})
-	if oErr != nil {
-		return oErr
-	}
-	return err
+	return unix.SetsockoptInt(u.sysFd, unix.SOL_SOCKET, unix.SO_SNDBUFFORCE, n)
 }
 
 func (u *StdConn) SetSoMark(mark int) error {
-	var err error
-	oErr := u.rc.Control(func(fd uintptr) {
-		err = unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_MARK, mark)
-	})
-	if oErr != nil {
-		return oErr
-	}
-	return err
+	return unix.SetsockoptInt(u.sysFd, unix.SOL_SOCKET, unix.SO_MARK, mark)
 }
 
 func (u *StdConn) GetRecvBuffer() (int, error) {
-	var err error
-	var n int
-	oErr := u.rc.Control(func(fd uintptr) {
-		n, err = unix.GetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_RCVBUF)
-	})
-	if oErr != nil {
-		return n, oErr
-	}
-	return n, err
+	return unix.GetsockoptInt(int(u.sysFd), unix.SOL_SOCKET, unix.SO_RCVBUF)
 }
 
 func (u *StdConn) GetSendBuffer() (int, error) {
-	var err error
-	var n int
-	oErr := u.rc.Control(func(fd uintptr) {
-		n, err = unix.GetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_SNDBUF)
-	})
-	if oErr != nil {
-		return n, oErr
-	}
-	return n, err
+	return unix.GetsockoptInt(int(u.sysFd), unix.SOL_SOCKET, unix.SO_SNDBUF)
 }
 
 func (u *StdConn) GetSoMark() (int, error) {
-	var err error
-	var n int
-	oErr := u.rc.Control(func(fd uintptr) {
-		n, err = unix.GetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_MARK)
-	})
-	if oErr != nil {
-		return n, oErr
-	}
-	return n, err
+	return unix.GetsockoptInt(int(u.sysFd), unix.SOL_SOCKET, unix.SO_MARK)
 }
 
 func (u *StdConn) LocalAddr() (netip.AddrPort, error) {
-	sa := u.c.LocalAddr()
-	return netip.ParseAddrPort(sa.String())
+	sa, err := unix.Getsockname(u.sysFd)
+	if err != nil {
+		return netip.AddrPort{}, err
+	}
+
+	switch sa := sa.(type) {
+	case *unix.SockaddrInet4:
+		return netip.AddrPortFrom(netip.AddrFrom4(sa.Addr), uint16(sa.Port)), nil
+
+	case *unix.SockaddrInet6:
+		return netip.AddrPortFrom(netip.AddrFrom16(sa.Addr), uint16(sa.Port)), nil
+
+	default:
+		return netip.AddrPort{}, fmt.Errorf("unsupported sock type: %T", sa)
+	}
 }
 
 func (u *StdConn) ListenOut(r EncReader) {
 	var ip netip.Addr
 
-	u.msgs, u.buffers, u.names = u.PrepareRawMessages(u.batch)
+	msgs, buffers, names := u.PrepareRawMessages(u.batch)
 	read := u.ReadMulti
 	if u.batch == 1 {
 		read = u.ReadSingle
 	}
 
 	for {
-		read()
-		if u.err != nil {
-			//TODO: remove logging, return error
-			u.l.WithError(u.err).Error("udp socket is closed, exiting read loop")
+		n, err := read(msgs)
+		if err != nil {
+			u.l.WithError(err).Debug("udp socket is closed, exiting read loop")
 			return
 		}
 
-		for i := 0; i < int(u.n); i++ {
+		for i := 0; i < n; i++ {
 			// Its ok to skip the ok check here, the slicing is the only error that can occur and it will panic
 			if u.isV4 {
-				ip, _ = netip.AddrFromSlice(u.names[i][4:8])
+				ip, _ = netip.AddrFromSlice(names[i][4:8])
 			} else {
-				ip, _ = netip.AddrFromSlice(u.names[i][8:24])
+				ip, _ = netip.AddrFromSlice(names[i][8:24])
 			}
-			//u.l.Error("GOT A PACKET", msgs[i].Len)
-			r(netip.AddrPortFrom(ip.Unmap(), binary.BigEndian.Uint16(u.names[i][2:4])), u.buffers[i][:u.msgs[i].Len])
+			r(netip.AddrPortFrom(ip.Unmap(), binary.BigEndian.Uint16(names[i][2:4])), buffers[i][:msgs[i].Len])
 		}
 	}
 }
 
-func (u *StdConn) ReadSingle() {
-	err := u.rc.Read(u.innerReadSingle)
-	if u.err == nil && err != nil {
-		u.err = err
-		u.n = 0
-		return
-	}
-}
-
-func (u *StdConn) innerReadSingle(fd uintptr) bool {
-	in, _, err := unix.Syscall6(
+func (u *StdConn) ReadSingle(msgs []rawMessage) (int, error) {
+	for {
+		n, _, err := unix.Syscall6(
 			unix.SYS_RECVMSG,
-		fd,
-		uintptr(unsafe.Pointer(&(u.msgs[0].Hdr))),
-		0, 0, 0, 0,
+			uintptr(u.sysFd),
+			uintptr(unsafe.Pointer(&(msgs[0].Hdr))),
+			0,
+			0,
+			0,
+			0,
 		)
 
-	if err == syscall.EAGAIN || err == syscall.EINTR {
-		// Retry read
-		return false
-
-	} else if err != 0 {
-		u.l.Errorf("READING FROM UDP SINGLE had an errno %d", err)
-		u.err = &net.OpError{Op: "recvmsg", Err: err}
-		u.n = 0
-		return true
+		if err != 0 {
+			if err == unix.EAGAIN || err == unix.EINTR {
+				continue
+			}
+			return 0, &net.OpError{Op: "recvmsg", Err: err}
 		}
 
-	u.msgs[0].Len = uint32(in)
-	u.n = 1
-	return true
-}
-
-func (u *StdConn) ReadMulti() {
-	err := u.rc.Read(u.innerReadMulti)
-	if u.err == nil && err != nil {
-		u.err = err
-		u.n = 0
-		return
+		msgs[0].Len = uint32(n)
+		return 1, nil
 	}
 }
 
-func (u *StdConn) innerReadMulti(fd uintptr) bool {
-	var err syscall.Errno
-	u.n, _, err = unix.Syscall6(
+func (u *StdConn) ReadMulti(msgs []rawMessage) (int, error) {
+	for {
+		n, _, err := unix.Syscall6(
 			unix.SYS_RECVMMSG,
-		fd,
-		uintptr(unsafe.Pointer(&u.msgs[0])),
-		uintptr(len(u.msgs)),
+			uintptr(u.sysFd),
+			uintptr(unsafe.Pointer(&msgs[0])),
+			uintptr(len(msgs)),
 			unix.MSG_WAITFORONE,
-		0, 0,
+			0,
+			0,
 		)
 
-	if err == syscall.EAGAIN || err == syscall.EINTR {
-		// Retry read
-		return false
-
-	} else if err != 0 {
-		u.l.Errorf("READING FROM UDP MULTI had an errno %d", err)
-		u.err = &net.OpError{Op: "recvmmsg", Err: err}
-		u.n = 0
-		return true
+		if err != 0 {
+			if err == unix.EAGAIN || err == unix.EINTR {
+				continue
+			}
+			return 0, &net.OpError{Op: "recvmmsg", Err: err}
 		}
 
-	return true
+		return int(n), nil
+	}
 }
 
 func (u *StdConn) WriteTo(b []byte, ip netip.AddrPort) error {
-	_, err := u.c.WriteToUDPAddrPort(b, ip)
-	return err
+	if u.isV4 {
+		return u.writeTo4(b, ip)
+	}
+	return u.writeTo6(b, ip)
+}
+
+func (u *StdConn) writeTo6(b []byte, ip netip.AddrPort) error {
+	var rsa unix.RawSockaddrInet6
+	rsa.Family = unix.AF_INET6
+	rsa.Addr = ip.Addr().As16()
+	binary.BigEndian.PutUint16((*[2]byte)(unsafe.Pointer(&rsa.Port))[:], ip.Port())
+
+	for {
+		_, _, err := unix.Syscall6(
+			unix.SYS_SENDTO,
+			uintptr(u.sysFd),
+			uintptr(unsafe.Pointer(&b[0])),
+			uintptr(len(b)),
+			uintptr(0),
+			uintptr(unsafe.Pointer(&rsa)),
+			uintptr(unix.SizeofSockaddrInet6),
+		)
+
+		if err != 0 {
+			return &net.OpError{Op: "sendto", Err: err}
+		}
+
+		return nil
+	}
+}
+
+func (u *StdConn) writeTo4(b []byte, ip netip.AddrPort) error {
+	if !ip.Addr().Is4() {
+		return fmt.Errorf("Listener is IPv4, but writing to IPv6 remote")
+	}
+
+	var rsa unix.RawSockaddrInet4
+	rsa.Family = unix.AF_INET
+	rsa.Addr = ip.Addr().As4()
+	binary.BigEndian.PutUint16((*[2]byte)(unsafe.Pointer(&rsa.Port))[:], ip.Port())
+
+	for {
+		_, _, err := unix.Syscall6(
+			unix.SYS_SENDTO,
+			uintptr(u.sysFd),
+			uintptr(unsafe.Pointer(&b[0])),
+			uintptr(len(b)),
+			uintptr(0),
+			uintptr(unsafe.Pointer(&rsa)),
+			uintptr(unix.SizeofSockaddrInet4),
+		)
+
+		if err != 0 {
+			return &net.OpError{Op: "sendto", Err: err}
+		}
+
+		return nil
+	}
 }
 
 func (u *StdConn) ReloadConfig(c *config.C) {
@@ -299,27 +304,15 @@ func (u *StdConn) ReloadConfig(c *config.C) {
 
 func (u *StdConn) getMemInfo(meminfo *[unix.SK_MEMINFO_VARS]uint32) error {
 	var vallen uint32 = 4 * unix.SK_MEMINFO_VARS
-	var err error
-	oErr := u.rc.Control(func(fd uintptr) {
-		_, _, err = unix.Syscall6(
-			unix.SYS_GETSOCKOPT,
-			fd,
-			uintptr(unix.SOL_SOCKET),
-			uintptr(unix.SO_MEMINFO),
-			uintptr(unsafe.Pointer(meminfo)),
-			uintptr(unsafe.Pointer(&vallen)),
-			0,
-		)
-	})
-	if oErr != nil {
-		return oErr
-	}
+	_, _, err := unix.Syscall6(unix.SYS_GETSOCKOPT, uintptr(u.sysFd), uintptr(unix.SOL_SOCKET), uintptr(unix.SO_MEMINFO), uintptr(unsafe.Pointer(meminfo)), uintptr(unsafe.Pointer(&vallen)), 0)
+	if err != 0 {
 		return err
+	}
+	return nil
 }
 
 func (u *StdConn) Close() error {
-	err := u.c.Close()
-	return err
+	return syscall.Close(u.sysFd)
 }
 
 func NewUDPStatsEmitter(udpConns []Conn) func() {