From 6e48647318edad7540c4e99be5aed10ac898893f Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Mon, 17 Jun 2019 13:08:13 +0200
Subject: tunnel: wait for IP service to attach to wintun

This helps fix startup races without needing to poll, as well as
reconfiguring interfaces after wintun destroys and re-adds. It also
deals gracefully with IPv6 being disabled.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 tunnel/interfacewatcher.go | 148 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 148 insertions(+)
 create mode 100644 tunnel/interfacewatcher.go

(limited to 'tunnel/interfacewatcher.go')

diff --git a/tunnel/interfacewatcher.go b/tunnel/interfacewatcher.go
new file mode 100644
index 00000000..b7a07f77
--- /dev/null
+++ b/tunnel/interfacewatcher.go
@@ -0,0 +1,148 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
+ */
+
+package tunnel
+
+import (
+	"log"
+	"sync"
+
+	"golang.org/x/sys/windows"
+	"golang.zx2c4.com/wireguard/device"
+	"golang.zx2c4.com/wireguard/tun"
+
+	"golang.zx2c4.com/wireguard/windows/conf"
+	"golang.zx2c4.com/wireguard/windows/services"
+	"golang.zx2c4.com/wireguard/windows/tunnel/firewall"
+	"golang.zx2c4.com/wireguard/windows/tunnel/winipcfg"
+)
+
+type interfaceWatcherError struct {
+	serviceError services.Error
+	err          error
+}
+type interfaceWatcherEvent struct {
+	luid   winipcfg.LUID
+	family winipcfg.AddressFamily
+}
+type interfaceWatcher struct {
+	errors chan interfaceWatcherError
+
+	device *device.Device
+	conf   *conf.Config
+	tun    *tun.NativeTun
+
+	setupMutex              sync.Mutex
+	routeChangeCallback4    *winipcfg.RouteChangeCallback
+	routeChangeCallback6    *winipcfg.RouteChangeCallback
+	interfaceChangeCallback *winipcfg.InterfaceChangeCallback
+	storedEvents            []interfaceWatcherEvent
+}
+
+func (iw *interfaceWatcher) setup(family winipcfg.AddressFamily) {
+	var routeChangeCallback **winipcfg.RouteChangeCallback
+	var ipversion string
+	if family == windows.AF_INET {
+		routeChangeCallback = &iw.routeChangeCallback4
+		ipversion = "v4"
+	} else if family == windows.AF_INET6 {
+		routeChangeCallback = &iw.routeChangeCallback6
+		ipversion = "v6"
+	} else {
+		return
+	}
+	if *routeChangeCallback != nil {
+		(*routeChangeCallback).Unregister()
+		*routeChangeCallback = nil
+	}
+	var err error
+
+	log.Printf("Monitoring default %s routes", ipversion)
+	*routeChangeCallback, err = monitorDefaultRoutes(family, iw.device, iw.conf.Interface.MTU == 0, iw.tun)
+	if err != nil {
+		iw.errors <- interfaceWatcherError{services.ErrorBindSocketsToDefaultRoutes, err}
+		return
+	}
+
+	log.Printf("Setting device %s addresses", ipversion)
+	err = configureInterface(family, iw.conf, iw.tun)
+	if err != nil {
+		iw.errors <- interfaceWatcherError{services.ErrorSetNetConfig, err}
+		return
+	}
+}
+
+func watchInterface() (*interfaceWatcher, error) {
+	iw := &interfaceWatcher{
+		errors: make(chan interfaceWatcherError, 2),
+	}
+	var err error
+	iw.interfaceChangeCallback, err = winipcfg.RegisterInterfaceChangeCallback(func(notificationType winipcfg.MibNotificationType, iface *winipcfg.MibIPInterfaceRow) {
+		iw.setupMutex.Lock()
+		defer iw.setupMutex.Unlock()
+
+		if notificationType != winipcfg.MibAddInstance {
+			return
+		}
+		if iw.tun == nil {
+			iw.storedEvents = append(iw.storedEvents, interfaceWatcherEvent{iface.InterfaceLUID, iface.Family})
+			return
+		}
+		if iface.InterfaceLUID != winipcfg.LUID(iw.tun.LUID()) {
+			return
+		}
+		iw.setup(iface.Family)
+	})
+	if err != nil {
+		return nil, err
+	}
+	return iw, nil
+}
+
+func (iw *interfaceWatcher) Configure(device *device.Device, conf *conf.Config, tun *tun.NativeTun) {
+	iw.setupMutex.Lock()
+	defer iw.setupMutex.Unlock()
+
+	iw.device, iw.conf, iw.tun = device, conf, tun
+	for _, event := range iw.storedEvents {
+		if event.luid == winipcfg.LUID(iw.tun.LUID()) {
+			iw.setup(event.family)
+		}
+	}
+	iw.storedEvents = nil
+}
+
+func (iw *interfaceWatcher) Destroy() {
+	iw.setupMutex.Lock()
+	defer iw.setupMutex.Unlock()
+
+	if iw.tun == nil {
+		return
+	}
+
+	if iw.routeChangeCallback4 != nil {
+		iw.routeChangeCallback4.Unregister()
+		iw.routeChangeCallback4 = nil
+	}
+	if iw.routeChangeCallback6 != nil {
+		iw.routeChangeCallback6.Unregister()
+		iw.routeChangeCallback6 = nil
+	}
+	if iw.interfaceChangeCallback != nil {
+		iw.interfaceChangeCallback.Unregister()
+		iw.interfaceChangeCallback = nil
+	}
+
+	firewall.DisableFirewall()
+
+	// It seems that the Windows networking stack doesn't like it when we destroy interfaces that have active
+	// routes, so to be certain, just remove everything before destroying.
+	luid := winipcfg.LUID(iw.tun.LUID())
+	luid.FlushRoutes(windows.AF_INET)
+	luid.FlushIPAddresses(windows.AF_INET)
+	luid.FlushRoutes(windows.AF_INET6)
+	luid.FlushIPAddresses(windows.AF_INET6)
+	luid.FlushDNS()
+}
-- 
cgit v1.2.3-59-g8ed1b