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/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
*/
package service
import (
"encoding/binary"
"errors"
"golang.org/x/sys/windows"
"golang.zx2c4.com/winipcfg"
"golang.zx2c4.com/wireguard/windows/conf"
"net"
"os"
"unsafe"
)
const (
sockoptIP_UNICAST_IF = 31
sockoptIPV6_UNICAST_IF = 31
)
func htonl(val uint32) uint32 {
bytes := make([]byte, 4)
binary.BigEndian.PutUint32(bytes, val)
return *(*uint32)(unsafe.Pointer(&bytes[0]))
}
func bindSocketRoute(family winipcfg.AddressFamily, bind *NativeBind, ourLuid uint64) error {
routes, err := winipcfg.GetRoutes(family)
if err != nil {
return err
}
lowestMetric := ^uint32(0)
index := uint32(0) // Zero is "unspecified", which for IP_UNICAST_IF resets the value, which is what we want.
for _, route := range routes {
if route.DestinationPrefix.PrefixLength != 0 || route.InterfaceLuid == ourLuid {
continue
}
if route.Metric < lowestMetric {
lowestMetric = route.Metric
index = route.InterfaceIndex
}
}
if family == winipcfg.AF_INET {
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(index)))
})
if err2 != nil {
return err2
}
if err != nil {
return err
}
return nil
} else if family == winipcfg.AF_INET6 {
sysconn, err := bind.ipv6.SyscallConn()
if err != nil {
return err
}
err2 := sysconn.Control(func(fd uintptr) {
// The lack of htonl here is not a bug. MSDN actually specifies big endian for one and little endian for the other.
err = windows.SetsockoptInt(windows.Handle(fd), windows.IPPROTO_IPV6, sockoptIPV6_UNICAST_IF, int(index))
})
if err2 != nil {
return err2
}
if err != nil {
return err
}
}
return nil
}
func monitorDefaultRoutes(bind *NativeBind, guid *windows.GUID) (*winipcfg.RouteChangeCallback, error) {
ourLuid, err := winipcfg.InterfaceGuidToLuid(guid)
if err != nil {
return nil, err
}
doIt := func() error {
err = bindSocketRoute(winipcfg.AF_INET, bind, ourLuid)
if err != nil {
return err
}
err = bindSocketRoute(winipcfg.AF_INET6, bind, ourLuid)
if err != nil {
return err
}
return nil
}
err = doIt()
if err != nil {
return nil, err
}
cb, err := winipcfg.RegisterRouteChangeCallback(func(notificationType winipcfg.MibNotificationType, route *winipcfg.Route) {
_ = doIt()
})
if err != nil {
return nil, err
}
return cb, nil
}
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
}
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