Rename tuntap package to tun

We haven't had TAP support in ages.

src/tun/tun_windows.go

@@ -0,0 +1,151 @@
+//go:build windows
+// +build windows
+
+package tun
+
+import (
+	"bytes"
+	"errors"
+	"log"
+	"net"
+
+	"github.com/yggdrasil-network/yggdrasil-go/src/defaults"
+	"golang.org/x/sys/windows"
+
+	wgtun "golang.zx2c4.com/wireguard/tun"
+	"golang.zx2c4.com/wireguard/windows/elevate"
+	"golang.zx2c4.com/wireguard/windows/tunnel/winipcfg"
+)
+
+// This is to catch Windows platforms
+
+// Configures the TUN adapter with the correct IPv6 address and MTU.
+func (tun *TunAdapter) setup(ifname string, addr string, mtu uint64) error {
+	if ifname == "auto" {
+		ifname = defaults.GetDefaults().DefaultIfName
+	}
+	return elevate.DoAsSystem(func() error {
+		var err error
+		var iface wgtun.Device
+		var guid windows.GUID
+		if guid, err = windows.GUIDFromString("{8f59971a-7872-4aa6-b2eb-061fc4e9d0a7}"); err != nil {
+			return err
+		}
+		if iface, err = wgtun.CreateTUNWithRequestedGUID(ifname, &guid, int(mtu)); err != nil {
+			return err
+		}
+		tun.iface = iface
+		if err = tun.setupAddress(addr); err != nil {
+			tun.log.Errorln("Failed to set up TUN address:", err)
+			return err
+		}
+		if err = tun.setupMTU(getSupportedMTU(mtu)); err != nil {
+			tun.log.Errorln("Failed to set up TUN MTU:", err)
+			return err
+		}
+		if mtu, err := iface.MTU(); err == nil {
+			tun.mtu = uint64(mtu)
+		}
+		return nil
+	})
+}
+
+// Sets the MTU of the TUN adapter.
+func (tun *TunAdapter) setupMTU(mtu uint64) error {
+	if tun.iface == nil || tun.Name() == "" {
+		return errors.New("Can't configure MTU as TUN adapter is not present")
+	}
+	if intf, ok := tun.iface.(*wgtun.NativeTun); ok {
+		luid := winipcfg.LUID(intf.LUID())
+		ipfamily, err := luid.IPInterface(windows.AF_INET6)
+		if err != nil {
+			return err
+		}
+
+		ipfamily.NLMTU = uint32(mtu)
+		intf.ForceMTU(int(ipfamily.NLMTU))
+		ipfamily.UseAutomaticMetric = false
+		ipfamily.Metric = 0
+		ipfamily.DadTransmits = 0
+		ipfamily.RouterDiscoveryBehavior = winipcfg.RouterDiscoveryDisabled
+
+		if err := ipfamily.Set(); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// Sets the IPv6 address of the TUN adapter.
+func (tun *TunAdapter) setupAddress(addr string) error {
+	if tun.iface == nil || tun.Name() == "" {
+		return errors.New("Can't configure IPv6 address as TUN adapter is not present")
+	}
+	if intf, ok := tun.iface.(*wgtun.NativeTun); ok {
+		if ipaddr, ipnet, err := net.ParseCIDR(addr); err == nil {
+			luid := winipcfg.LUID(intf.LUID())
+			addresses := append([]net.IPNet{}, net.IPNet{
+				IP:   ipaddr,
+				Mask: ipnet.Mask,
+			})
+
+			err := luid.SetIPAddressesForFamily(windows.AF_INET6, addresses)
+			if err == windows.ERROR_OBJECT_ALREADY_EXISTS {
+				cleanupAddressesOnDisconnectedInterfaces(windows.AF_INET6, addresses)
+				err = luid.SetIPAddressesForFamily(windows.AF_INET6, addresses)
+			}
+			if err != nil {
+				return err
+			}
+		} else {
+			return err
+		}
+	} else {
+		return errors.New("unable to get NativeTUN")
+	}
+	return nil
+}
+
+/*
+ * cleanupAddressesOnDisconnectedInterfaces
+ * SPDX-License-Identifier: MIT
+ * Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
+ */
+func cleanupAddressesOnDisconnectedInterfaces(family winipcfg.AddressFamily, addresses []net.IPNet) {
+	if len(addresses) == 0 {
+		return
+	}
+	includedInAddresses := func(a net.IPNet) bool {
+		// TODO: this makes the whole algorithm O(n^2). But we can't stick net.IPNet in a Go hashmap. Bummer!
+		for _, addr := range addresses {
+			ip := addr.IP
+			if ip4 := ip.To4(); ip4 != nil {
+				ip = ip4
+			}
+			mA, _ := addr.Mask.Size()
+			mB, _ := a.Mask.Size()
+			if bytes.Equal(ip, a.IP) && mA == mB {
+				return true
+			}
+		}
+		return false
+	}
+	interfaces, err := winipcfg.GetAdaptersAddresses(family, winipcfg.GAAFlagDefault)
+	if err != nil {
+		return
+	}
+	for _, iface := range interfaces {
+		if iface.OperStatus == winipcfg.IfOperStatusUp {
+			continue
+		}
+		for address := iface.FirstUnicastAddress; address != nil; address = address.Next {
+			ip := address.Address.IP()
+			ipnet := net.IPNet{IP: ip, Mask: net.CIDRMask(int(address.OnLinkPrefixLength), 8*len(ip))}
+			if includedInAddresses(ipnet) {
+				log.Printf("Cleaning up stale address %s from interface ‘%s’", ipnet.String(), iface.FriendlyName())
+				iface.LUID.DeleteIPAddress(ipnet)
+			}
+		}
+	}
+}