mirror of
https://git.zx2c4.com/wireguard-go
synced 2024-11-14 16:55:15 +01:00
net: implement ECN handling, rfc6040 style
To decide whether we should use the compatibility mode or the normal mode with a peer, we use the handshake messages as a signaling channel. If we receive the expected ECN bits, it most likely means they're running a compatible version. Signed-off-by: Florent Daigniere <nextgens@freenetproject.org>
This commit is contained in:
Florent Daigniere
parent
9e686cd714
commit
0c2d06d8a5
4
conn.go
4
conn.go
@ -20,8 +20,8 @@ const (
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*/
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type Bind interface {
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SetMark(value uint32) error
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ReceiveIPv6(buff []byte) (int, Endpoint, error)
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ReceiveIPv4(buff []byte) (int, Endpoint, error)
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ReceiveIPv6(buff []byte) (int, Endpoint, byte, error)
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ReceiveIPv4(buff []byte) (int, Endpoint, byte, error)
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Send(buff []byte, end Endpoint, tos byte) error
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Close() error
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}
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@ -133,26 +133,29 @@ func (bind *NativeBind) Close() error {
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return err2
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}
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func (bind *NativeBind) ReceiveIPv4(buff []byte) (int, Endpoint, error) {
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// TODO: implement TOS
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func (bind *NativeBind) ReceiveIPv4(buff []byte) (int, Endpoint, byte, error) {
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if bind.ipv4 == nil {
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return 0, nil, syscall.EAFNOSUPPORT
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return 0, nil, 0, syscall.EAFNOSUPPORT
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}
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n, endpoint, err := bind.ipv4.ReadFromUDP(buff)
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if endpoint != nil {
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endpoint.IP = endpoint.IP.To4()
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}
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return n, (*NativeEndpoint)(endpoint), err
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return n, (*NativeEndpoint)(endpoint), 0, err
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}
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func (bind *NativeBind) ReceiveIPv6(buff []byte) (int, Endpoint, error) {
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// TODO: implement TOS
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func (bind *NativeBind) ReceiveIPv6(buff []byte) (int, Endpoint, byte, error) {
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if bind.ipv6 == nil {
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return 0, nil, syscall.EAFNOSUPPORT
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return 0, nil, 0, syscall.EAFNOSUPPORT
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}
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n, endpoint, err := bind.ipv6.ReadFromUDP(buff)
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return n, (*NativeEndpoint)(endpoint), err
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return n, (*NativeEndpoint)(endpoint), 0, err
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}
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func (bind *NativeBind) Send(buff []byte, endpoint Endpoint) error {
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// TODO: implement TOS
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func (bind *NativeBind) Send(buff []byte, endpoint Endpoint, tos byte) error {
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var err error
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nend := endpoint.(*NativeEndpoint)
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if nend.IP.To4() != nil {
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@ -232,30 +232,32 @@ func (bind *NativeBind) Close() error {
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return err3
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}
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func (bind *NativeBind) ReceiveIPv6(buff []byte) (int, Endpoint, error) {
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func (bind *NativeBind) ReceiveIPv6(buff []byte) (int, Endpoint, byte, error) {
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var end NativeEndpoint
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var tos byte
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if bind.sock6 == -1 {
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return 0, nil, syscall.EAFNOSUPPORT
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return 0, nil, tos, syscall.EAFNOSUPPORT
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}
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n, err := receive6(
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n, tos, err := receive6(
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bind.sock6,
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buff,
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&end,
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)
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return n, &end, err
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return n, &end, tos, err
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}
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func (bind *NativeBind) ReceiveIPv4(buff []byte) (int, Endpoint, error) {
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func (bind *NativeBind) ReceiveIPv4(buff []byte) (int, Endpoint, byte, error) {
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var end NativeEndpoint
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var tos byte
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if bind.sock4 == -1 {
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return 0, nil, syscall.EAFNOSUPPORT
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return 0, nil, tos, syscall.EAFNOSUPPORT
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}
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n, err := receive4(
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n, tos, err := receive4(
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bind.sock4,
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buff,
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&end,
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)
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return n, &end, err
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return n, &end, tos, err
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}
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func (bind *NativeBind) Send(buff []byte, end Endpoint, tos byte) error {
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@ -384,6 +386,15 @@ func create4(port uint16) (int, uint16, error) {
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return err
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}
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if err := unix.SetsockoptInt(
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fd,
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unix.IPPROTO_IP,
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unix.IP_RECVTOS,
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1,
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); err != nil {
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return err
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}
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return unix.Bind(fd, &addr)
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}(); err != nil {
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unix.Close(fd)
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@ -442,6 +453,15 @@ func create6(port uint16) (int, uint16, error) {
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return err
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}
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if err := unix.SetsockoptInt(
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fd,
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unix.IPPROTO_IPV6,
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unix.IPV6_RECVTCLASS,
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1,
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); err != nil {
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return err
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}
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return unix.Bind(fd, &addr)
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}(); err != nil {
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@ -452,12 +472,13 @@ func create6(port uint16) (int, uint16, error) {
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return fd, uint16(addr.Port), err
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}
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type ipTos struct {
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tos byte
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}
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func send4(sock int, end *NativeEndpoint, buff []byte, tos byte) error {
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// construct message header
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type ipTos struct {
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tos byte
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}
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cmsg := struct {
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cmsghdr unix.Cmsghdr
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@ -505,9 +526,6 @@ func send4(sock int, end *NativeEndpoint, buff []byte, tos byte) error {
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func send6(sock int, end *NativeEndpoint, buff []byte, tos byte) error {
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// construct message header
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type ipTos struct {
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tos byte
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}
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cmsg := struct {
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cmsghdr unix.Cmsghdr
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@ -555,19 +573,21 @@ func send6(sock int, end *NativeEndpoint, buff []byte, tos byte) error {
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return err
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}
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func receive4(sock int, buff []byte, end *NativeEndpoint) (int, error) {
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func receive4(sock int, buff []byte, end *NativeEndpoint) (int, byte, error) {
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// contruct message header
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var cmsg struct {
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cmsghdr unix.Cmsghdr
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pktinfo unix.Inet4Pktinfo
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cmsghdr unix.Cmsghdr
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pktinfo unix.Inet4Pktinfo
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cmsghdr2 unix.Cmsghdr
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iptos ipTos
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}
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size, _, _, newDst, err := unix.Recvmsg(sock, buff, (*[unsafe.Sizeof(cmsg)]byte)(unsafe.Pointer(&cmsg))[:], 0)
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if err != nil {
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return 0, err
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return 0, 0, err
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}
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end.isV6 = false
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@ -576,7 +596,6 @@ func receive4(sock int, buff []byte, end *NativeEndpoint) (int, error) {
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}
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// update source cache
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if cmsg.cmsghdr.Level == unix.IPPROTO_IP &&
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cmsg.cmsghdr.Type == unix.IP_PKTINFO &&
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cmsg.cmsghdr.Len >= unix.SizeofInet4Pktinfo {
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@ -584,22 +603,31 @@ func receive4(sock int, buff []byte, end *NativeEndpoint) (int, error) {
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end.src4().ifindex = cmsg.pktinfo.Ifindex
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}
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return size, nil
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tos := byte(0)
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if cmsg.cmsghdr2.Level == unix.IPPROTO_IP &&
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cmsg.cmsghdr2.Type == unix.IP_TOS &&
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cmsg.cmsghdr2.Len >= 1 {
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tos = cmsg.iptos.tos
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}
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return size, tos, nil
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}
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func receive6(sock int, buff []byte, end *NativeEndpoint) (int, error) {
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func receive6(sock int, buff []byte, end *NativeEndpoint) (int, byte, error) {
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// contruct message header
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var cmsg struct {
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cmsghdr unix.Cmsghdr
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pktinfo unix.Inet6Pktinfo
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cmsghdr unix.Cmsghdr
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pktinfo unix.Inet6Pktinfo
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cmsghdr2 unix.Cmsghdr
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iptos ipTos
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}
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size, _, _, newDst, err := unix.Recvmsg(sock, buff, (*[unsafe.Sizeof(cmsg)]byte)(unsafe.Pointer(&cmsg))[:], 0)
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if err != nil {
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return 0, err
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return 0, 0, err
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}
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end.isV6 = true
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@ -616,7 +644,14 @@ func receive6(sock int, buff []byte, end *NativeEndpoint) (int, error) {
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end.dst6().ZoneId = cmsg.pktinfo.Ifindex
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}
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return size, nil
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tos := byte(0)
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if cmsg.cmsghdr2.Level == unix.IPPROTO_IPV6 &&
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cmsg.cmsghdr2.Type == unix.IPV6_TCLASS &&
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cmsg.cmsghdr2.Len >= 1 {
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tos = cmsg.iptos.tos
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}
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return size, tos, nil
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}
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func (bind *NativeBind) routineRouteListener(device *Device) {
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59
misc.go
59
misc.go
@ -46,3 +46,62 @@ func min(a, b uint) uint {
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}
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return a
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}
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// called from receive
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func ecn_rfc6040_egress(inner byte, outer byte) (byte, bool) {
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/*
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+---------+------------------------------------------------+
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|Arriving | Arriving Outer Header |
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| Inner +---------+------------+------------+------------+
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| Header | Not-ECT | ECT(0) | ECT(1) | CE |
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+---------+---------+------------+------------+------------+
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| Not-ECT | Not-ECT |Not-ECT(!!!)|Not-ECT(!!!)| <drop>(!!!)|
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| ECT(0) | ECT(0) | ECT(0) | ECT(1) | CE |
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| ECT(1) | ECT(1) | ECT(1) (!) | ECT(1) | CE |
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| CE | CE | CE | CE(!!!)| CE |
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+---------+---------+------------+------------+------------+
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*/
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innerECN := CongestionExperienced & inner
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outerECN := CongestionExperienced & outer
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switch outerECN {
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case CongestionExperienced:
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switch innerECN {
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case NotECNTransport:
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return 0, true
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}
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return (inner & (CongestionExperienced ^ 255)) | CongestionExperienced, false
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case ECNTransport1:
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switch innerECN {
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case ECNTransport0:
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return (inner & (CongestionExperienced ^ 255)) | ECNTransport1, false
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}
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}
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return inner, false
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}
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// called from send
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func ecn_rfc6040_ingress(inner byte, useNormalMode bool) byte {
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/*
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+-----------------+-------------------------------+
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| Incoming Header | Departing Outer Header |
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| (also equal to +---------------+---------------+
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| departing Inner | Compatibility | Normal |
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| Header) | Mode | Mode |
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+-----------------+---------------+---------------+
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| Not-ECT | Not-ECT | Not-ECT |
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| ECT(0) | Not-ECT | ECT(0) |
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| ECT(1) | Not-ECT | ECT(1) |
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| CE | Not-ECT | CE |
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+-----------------+---------------+---------------+
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*/
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if !useNormalMode {
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inner &= (CongestionExperienced ^ 255)
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}
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return inner
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}
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func ecn_rfc6040_enabled(tos byte) bool {
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return (CongestionExperienced & tos) == ECNTransport0
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}
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9
peer.go
9
peer.go
@ -15,6 +15,14 @@ import (
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const (
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PeerRoutineNumber = 3
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DiffServAF41 = 0x88 // AF41
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NotECNTransport = 0x00 // Not-ECT (Not ECN-Capable Transport)
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ECNTransport1 = 0x01 // ECT(1) (ECN-Capable Transport(1))
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ECNTransport0 = 0x02 // ECT(0) (ECN-Capable Transport(0))
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CongestionExperienced = 0x03 // CE (Congestion Experienced)
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HandshakeDSCP = DiffServAF41 | ECNTransport0 // AF41, plus 10 ECN
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)
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type Peer struct {
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@ -25,6 +33,7 @@ type Peer struct {
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device *Device
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endpoint Endpoint
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persistentKeepaliveInterval uint16
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isECNConfirmed AtomicBool
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// This must be 64-bit aligned, so make sure the above members come out to even alignment and pad accordingly
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stats struct {
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19
receive.go
19
receive.go
@ -23,6 +23,7 @@ type QueueHandshakeElement struct {
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packet []byte
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endpoint Endpoint
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buffer *[MaxMessageSize]byte
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isECNCompatible bool
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}
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type QueueInboundElement struct {
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@ -33,6 +34,7 @@ type QueueInboundElement struct {
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counter uint64
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keypair *Keypair
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endpoint Endpoint
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tos byte
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}
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func (elem *QueueInboundElement) Drop() {
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@ -108,6 +110,7 @@ func (device *Device) RoutineReceiveIncoming(IP int, bind Bind) {
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err error
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size int
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endpoint Endpoint
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outerTOS byte
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)
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for {
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@ -116,9 +119,9 @@ func (device *Device) RoutineReceiveIncoming(IP int, bind Bind) {
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switch IP {
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case ipv4.Version:
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size, endpoint, err = bind.ReceiveIPv4(buffer[:])
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size, endpoint, outerTOS, err = bind.ReceiveIPv4(buffer[:])
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case ipv6.Version:
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size, endpoint, err = bind.ReceiveIPv6(buffer[:])
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size, endpoint, outerTOS, err = bind.ReceiveIPv6(buffer[:])
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default:
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panic("invalid IP version")
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}
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@ -178,6 +181,7 @@ func (device *Device) RoutineReceiveIncoming(IP int, bind Bind) {
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elem.endpoint = endpoint
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elem.counter = 0
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elem.Mutex = sync.Mutex{}
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elem.tos = outerTOS
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elem.Lock()
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// add to decryption queues
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@ -213,6 +217,7 @@ func (device *Device) RoutineReceiveIncoming(IP int, bind Bind) {
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buffer: buffer,
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packet: packet,
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endpoint: endpoint,
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isECNCompatible: ecn_rfc6040_enabled(outerTOS),
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},
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)) {
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buffer = device.GetMessageBuffer()
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@ -426,7 +431,7 @@ func (device *Device) RoutineHandshake() {
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peer.SetEndpointFromPacket(elem.endpoint)
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logDebug.Println(peer, "- Received handshake initiation")
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peer.isECNConfirmed.Set(elem.isECNCompatible)
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peer.SendHandshakeResponse()
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case MessageResponseType:
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@ -473,6 +478,7 @@ func (device *Device) RoutineHandshake() {
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peer.timersSessionDerived()
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peer.timersHandshakeComplete()
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peer.isECNConfirmed.Set(elem.isECNCompatible)
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peer.SendKeepalive()
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select {
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case peer.signals.newKeypairArrived <- struct{}{}:
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@ -565,6 +571,7 @@ func (peer *Peer) RoutineSequentialReceiver() {
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}
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peer.timersDataReceived()
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var shouldDrop bool
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// verify source and strip padding
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switch elem.packet[0] >> 4 {
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@ -595,6 +602,7 @@ func (peer *Peer) RoutineSequentialReceiver() {
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continue
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}
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elem.tos, shouldDrop = ecn_rfc6040_egress(elem.packet[1], elem.tos)
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case ipv6.Version:
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// strip padding
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@ -623,10 +631,15 @@ func (peer *Peer) RoutineSequentialReceiver() {
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continue
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}
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elem.tos, shouldDrop = ecn_rfc6040_egress(elem.packet[1], elem.tos);
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default:
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logInfo.Println("Packet with invalid IP version from", peer)
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continue
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}
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if shouldDrop {
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logInfo.Println("ECN/Congestion detected, dropping packet from", peer)
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continue
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}
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// write to tun device
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14
send.go
14
send.go
@ -41,10 +41,6 @@ import (
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* (to allow the construction of transport messages in-place)
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*/
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const (
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HandshakeDSCP = 0x88 // AF41, plus 00 ECN
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)
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type QueueOutboundElement struct {
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dropped int32
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sync.Mutex
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@ -299,14 +295,20 @@ func (device *Device) RoutineReadFromTUN() {
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}
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dst := elem.packet[IPv4offsetDst : IPv4offsetDst+net.IPv4len]
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peer = device.allowedips.LookupIPv4(dst)
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elem.tos = elem.packet[1];
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if peer == nil {
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continue
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}
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elem.tos = ecn_rfc6040_ingress(elem.packet[1], peer.isECNConfirmed.Get())
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case ipv6.Version:
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if len(elem.packet) < ipv6.HeaderLen {
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continue
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}
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dst := elem.packet[IPv6offsetDst : IPv6offsetDst+net.IPv6len]
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peer = device.allowedips.LookupIPv6(dst)
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elem.tos = elem.packet[1];
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if peer == nil {
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continue
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}
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elem.tos = ecn_rfc6040_ingress(elem.packet[1], peer.isECNConfirmed.Get())
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default:
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logDebug.Println("Received packet with unknown IP version")
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}
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