aboutsummaryrefslogtreecommitdiffstatshomepage
path: root/service/ifaceconfig.go
blob: c6a8257d7dc9ff571b6ff3e54b432655572fb5b4 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
/* SPDX-License-Identifier: MIT
 *
 * Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
 */

package service

import (
	"bytes"
	"encoding/binary"
	"errors"
	"golang.org/x/sys/windows"
	"golang.zx2c4.com/winipcfg"
	"golang.zx2c4.com/wireguard/device"
	"golang.zx2c4.com/wireguard/windows/conf"
	"net"
	"sort"
	"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, device *device.Device, ourLuid uint64, lastLuid *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.
	luid := uint64(0) // Hopefully luid zero is unspecified, but hard to find docs saying so.
	for _, route := range routes {
		if route.DestinationPrefix.PrefixLength != 0 || route.InterfaceLuid == ourLuid {
			continue
		}
		if route.Metric < lowestMetric {
			lowestMetric = route.Metric
			index = route.InterfaceIndex
			luid = route.InterfaceLuid
		}
	}
	if luid == *lastLuid {
		return nil
	}
	*lastLuid = luid
	if family == winipcfg.AF_INET {
		return device.BindSocketToInterface4(index)
	} else if family == winipcfg.AF_INET6 {
		return device.BindSocketToInterface6(index)
	}
	return nil
}

func monitorDefaultRoutes(device *device.Device, guid *windows.GUID) (*winipcfg.RouteChangeCallback, error) {
	ourLuid, err := winipcfg.InterfaceGuidToLuid(guid)
	lastLuid4 := uint64(0)
	lastLuid6 := uint64(0)
	if err != nil {
		return nil, err
	}
	doIt := func() error {
		err = bindSocketRoute(winipcfg.AF_INET, device, ourLuid, &lastLuid4)
		if err != nil {
			return err
		}
		err = bindSocketRoute(winipcfg.AF_INET6, device, ourLuid, &lastLuid6)
		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) {
		if route.DestinationPrefix.PrefixLength == 0 {
			_ = 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
	}

	deduplicatedRoutes := make([]*winipcfg.RouteData, routeCount)
	routeCount = 0
	sort.Slice(routes, func(i, j int) bool {
		if routes[i].Metric < routes[j].Metric {
			return true
		}
		if bytes.Compare(routes[i].NextHop, routes[j].NextHop) == -1 {
			return true
		}
		if bytes.Compare(routes[i].Destination.IP, routes[j].Destination.IP) == -1 {
			return true
		}
		if bytes.Compare(routes[i].Destination.Mask, routes[j].Destination.Mask) == -1 {
			return true
		}
		return false
	})
	for i := 0; i < len(routes); i++ {
		if i > 0 && routes[i].Metric == routes[i - 1].Metric &&
			bytes.Equal(routes[i].NextHop, routes[i - 1].NextHop) &&
			bytes.Equal(routes[i].Destination.IP, routes[i - 1].Destination.IP) &&
			bytes.Equal(routes[i].Destination.Mask, routes[i - 1].Destination.Mask) {
			continue
		}
		deduplicatedRoutes[routeCount] = &routes[i]
		routeCount++
	}

	err = iface.SetRoutes(deduplicatedRoutes, false)
	if err != nil {
		return nil
	}

	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
}