1 files changed, 184 insertions, 0 deletions
diff --git a/service/ifaceconfig.go b/service/ifaceconfig.go
new file mode 100644
index 00000000..c405939c
--- /dev/null
+++ b/service/ifaceconfig.go
@@ -0,0 +1,184 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
+ */
+
+package service
+
+import (
+	"errors"
+	"golang.org/x/sys/windows"
+	"golang.zx2c4.com/winipcfg"
+	"golang.zx2c4.com/wireguard/windows/conf"
+	"net"
+	"os"
+)
+
+const (
+	sockoptIP_UNICAST_IF   = 31
+	sockoptIPV6_UNICAST_IF = 31
+)
+
+func bindSocketToMonitoredDefault(bind *NativeBind) error {
+	defaultIface, err := winipcfg.DefaultInterface(winipcfg.AF_INET)
+	if err != nil {
+		return err
+	}
+	sysconn, err := bind.ipv4.SyscallConn()
+	if err != nil {
+		return err
+	}
+	err2 := sysconn.Control(func(fd uintptr) {
+		err = windows.SetsockoptInt(windows.Handle(fd), windows.IPPROTO_IP, sockoptIP_UNICAST_IF, int(htonl(defaultIface.Index)))
+	})
+	if err2 != nil {
+		return err2
+	}
+	if err != nil {
+		return err
+	}
+	defaultIface, err = winipcfg.DefaultInterface(winipcfg.AF_INET6)
+	if err != nil {
+		return err
+	}
+	sysconn, err = bind.ipv6.SyscallConn()
+	if err != nil {
+		return err
+	}
+	err2 = sysconn.Control(func(fd uintptr) {
+		err = windows.SetsockoptInt(windows.Handle(fd), windows.IPPROTO_IPV6, sockoptIPV6_UNICAST_IF, int(defaultIface.Ipv6IfIndex))
+	})
+	if err2 != nil {
+		return err2
+	}
+	if err != nil {
+		return err
+	}
+
+	return nil
+
+	//TODO: monitor for changes, and make sure we're using default modulo us
+}
+
+func configureInterface(conf *conf.Config, guid *windows.GUID) error {
+	iface, err := winipcfg.InterfaceFromGUID(guid)
+	if err != nil {
+		return err
+	}
+
+	routeCount := len(conf.Interface.Addresses)
+	for _, peer := range conf.Peers {
+		routeCount += len(peer.AllowedIPs)
+	}
+	routes := make([]winipcfg.RouteData, routeCount)
+	routeCount = 0
+	var firstGateway4 *net.IP
+	var firstGateway6 *net.IP
+	addresses := make([]*net.IPNet, len(conf.Interface.Addresses))
+	for i, addr := range conf.Interface.Addresses {
+		ipnet := addr.IPNet()
+		addresses[i] = &ipnet
+		gateway := ipnet.IP.Mask(ipnet.Mask)
+		if addr.Bits() == 32 && firstGateway4 == nil {
+			firstGateway4 = &gateway
+		} else if addr.Bits() == 128 && firstGateway6 == nil {
+			firstGateway6 = &gateway
+		}
+		routes[routeCount] = winipcfg.RouteData{
+			Destination: net.IPNet{
+				IP:   gateway,
+				Mask: ipnet.Mask,
+			},
+			NextHop: gateway,
+			Metric:  0,
+		}
+		routeCount++
+	}
+
+	foundDefault4 := false
+	foundDefault6 := false
+	for _, peer := range conf.Peers {
+		for _, allowedip := range peer.AllowedIPs {
+			if (allowedip.Bits() == 32 && firstGateway4 == nil) || (allowedip.Bits() == 128 && firstGateway6 == nil) {
+				return errors.New("Due to a Windows limitation, one cannot have interface routes without an interface address")
+			}
+			routes[routeCount] = winipcfg.RouteData{
+				Destination: allowedip.IPNet(),
+				Metric:      0,
+			}
+			if allowedip.Bits() == 32 {
+				if allowedip.Cidr == 0 {
+					foundDefault4 = true
+				}
+				routes[routeCount].NextHop = *firstGateway4
+			} else if allowedip.Bits() == 128 {
+				if allowedip.Cidr == 0 {
+					foundDefault6 = true
+				}
+				routes[routeCount].NextHop = *firstGateway6
+			}
+			routeCount++
+		}
+	}
+
+	err = iface.SetAddresses(addresses)
+	if err != nil {
+		return err
+	}
+
+	err = iface.FlushRoutes()
+	if err != nil {
+		return nil
+	}
+	for _, route := range routes {
+		err = iface.AddRoute(&route, false)
+
+		//TODO: Ignoring duplicate errors like this maybe isn't very reasonable.
+		// instead we should make sure we're not adding duplicates ourselves when
+		// inserting the gateway routes.
+		if syserr, ok := err.(*os.SyscallError); ok {
+			if syserr.Err == windows.Errno(ERROR_OBJECT_ALREADY_EXISTS) {
+				err = nil
+			}
+		}
+
+		if err != nil {
+			return err
+		}
+	}
+
+	err = iface.SetDNS(conf.Interface.Dns)
+	if err != nil {
+		return err
+	}
+
+	ipif, err := iface.GetIpInterface(winipcfg.AF_INET)
+	if err != nil {
+		return err
+	}
+	if foundDefault4 {
+		ipif.UseAutomaticMetric = false
+		ipif.Metric = 0
+	}
+	err = ipif.Set()
+	if err != nil {
+		return err
+	}
+
+	ipif, err = iface.GetIpInterface(winipcfg.AF_INET6)
+	if err != nil {
+		return err
+	}
+	if foundDefault6 {
+		ipif.UseAutomaticMetric = false
+		ipif.Metric = 0
+	}
+	ipif.DadTransmits = 0
+	ipif.RouterDiscoveryBehavior = winipcfg.RouterDiscoveryDisabled
+	err = ipif.Set()
+	if err != nil {
+		return err
+	}
+
+	return nil
+}