dhcp

WIP: implement wgOnEvent
WIP: debug
WIP: netstack: implement dhcp and ipvlan
WIP: implement dhcp in tunnel
WIP: add dhcp information to detail

12 files changed, 562 insertions, 30 deletions

diff --git a/tunnel/src/main/java/com/wireguard/android/backend/Backend.java b/tunnel/src/main/java/com/wireguard/android/backend/Backend.java
index 5aaad826..1d9be593 100644
--- a/tunnel/src/main/java/com/wireguard/android/backend/Backend.java
+++ b/tunnel/src/main/java/com/wireguard/android/backend/Backend.java
@@ -18,6 +18,8 @@ import androidx.annotation.Nullable;
 
 @NonNullForAll
 public interface Backend {
+    DhcpInfo getDhcpInfo(Tunnel tunnel) throws Exception;
+
     /**
      * Enumerate names of currently-running tunnels.
      *
diff --git a/tunnel/src/main/java/com/wireguard/android/backend/DhcpInfo.java b/tunnel/src/main/java/com/wireguard/android/backend/DhcpInfo.java
new file mode 100644
index 00000000..35a7dd43
--- /dev/null
+++ b/tunnel/src/main/java/com/wireguard/android/backend/DhcpInfo.java
@@ -0,0 +1,57 @@
+/*
+ * Copyright © 2020 WireGuard LLC. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package com.wireguard.android.backend;
+
+import android.os.SystemClock;
+import android.util.Pair;
+
+import com.wireguard.crypto.Key;
+import com.wireguard.util.NonNullForAll;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Class representing DHCP info for a {@link Tunnel} instance.
+ */
+@NonNullForAll
+public class DhcpInfo {
+    private String info;
+    private long lastTouched = SystemClock.elapsedRealtime();
+
+    DhcpInfo() {
+    }
+
+    /**
+     * Add a peer and its current data usage to the internal map.
+     *
+     * @param key A WireGuard public key bound to a particular peer
+     * @param rx  The received traffic for the {@link com.wireguard.config.Peer} referenced by
+     *            the provided {@link Key}. This value is in bytes
+     * @param tx  The transmitted traffic for the {@link com.wireguard.config.Peer} referenced by
+     *            the provided {@link Key}. This value is in bytes.
+     */
+    void set(final String info) {
+        this.info = info;
+        lastTouched = SystemClock.elapsedRealtime();
+    }
+
+    /**
+     * Check if the statistics are stale, indicating the need for the {@link Backend} to update them.
+     *
+     * @return boolean indicating if the current statistics instance has stale values.
+     */
+    public boolean isStale() {
+        return SystemClock.elapsedRealtime() - lastTouched > 900;
+    }
+
+    /**
+     */
+    public String get() {
+        return info;
+    }
+
+}
diff --git a/tunnel/src/main/java/com/wireguard/android/backend/GoBackend.java b/tunnel/src/main/java/com/wireguard/android/backend/GoBackend.java
index e8148c04..4e0a9f94 100644
--- a/tunnel/src/main/java/com/wireguard/android/backend/GoBackend.java
+++ b/tunnel/src/main/java/com/wireguard/android/backend/GoBackend.java
@@ -46,6 +46,7 @@ import com.wireguard.config.Config;
 import com.wireguard.config.HttpProxy;
 import com.wireguard.config.InetEndpoint;
 import com.wireguard.config.InetNetwork;
+import com.wireguard.config.ParseException;
 import com.wireguard.config.Peer;
 import com.wireguard.crypto.Key;
 import com.wireguard.crypto.KeyFormatException;
@@ -71,6 +72,7 @@ import java.net.UnknownHostException;
 import java.net.URL;
 import java.nio.ByteOrder;
 import java.util.Collections;
+import java.util.LinkedHashSet;
 import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.CountDownLatch;
@@ -91,7 +93,7 @@ import androidx.collection.ArraySet;
  * WireGuard tunnels.
  */
 @NonNullForAll
-public final class GoBackend implements Backend {
+public final class GoBackend implements Backend, EventHandler {
     private static final int DNS_RESOLUTION_RETRIES = 10;
     private static final String TAG = "WireGuard/GoBackend";
     @Nullable private static AlwaysOnCallback alwaysOnCallback;
@@ -140,14 +142,29 @@ public final class GoBackend implements Backend {
 
     private static native int wgGetSocketV6(int handle);
 
+    private static native void wgSetFd(int handle, int tunFd);
+
     private static native void wgTurnOff(int handle);
 
-    private static native int wgTurnOn(String ifName, int tunFd, String settings);
+    private static native int wgTurnOn(String ifName, int tunFd, String settings, EventHandler handler);
+
+    private static native int wgTurnOnDhcp(String ifName, String settings, EventHandler handler);
 
     private static native String wgVersion();
 
     private static native int wgStartGrpc(String sockName);
 
+    @Override
+    public DhcpInfo getDhcpInfo(final Tunnel tunnel) {
+        final DhcpInfo info = new DhcpInfo();
+        if (tunnel != currentTunnel) {
+            return info;
+        }
+	// TODO update info
+	info.set("FIXME");
+	return info;
+    }
+
     /**
      * Method to get the names of running tunnels.
      *
@@ -426,14 +443,9 @@ public final class GoBackend implements Backend {
         Log.i(TAG, "Exit streamReverse");
     }
 
-    private void setStateInternal(final Tunnel tunnel, @Nullable final Config config, final State state)
+    private void setStateInternalFinalize(final Tunnel tunnel, @Nullable final Config config, Set<InetNetwork> addresses)
             throws Exception {
-        Log.i(TAG, "Bringing tunnel " + tunnel.getName() + ' ' + state);
-
-        if (state == State.UP) {
-            if (config == null)
-                throw new BackendException(Reason.TUNNEL_MISSING_CONFIG);
-
+        if (true) { // Add scope to avoid changing indentation level
             if (VpnService.prepare(context) != null)
                 throw new BackendException(Reason.VPN_NOT_AUTHORIZED);
 
@@ -452,18 +464,13 @@ public final class GoBackend implements Backend {
             }
             service.setOwner(this);
 
-            if (currentTunnelHandle != -1) {
-                Log.w(TAG, "Tunnel already up");
-                return;
-            }
-
-
             activeNetwork = connectivityManager.getActiveNetwork();
             if (!connectivityManager.getNetworkCapabilities(activeNetwork).hasCapability(NetworkCapabilities.NET_CAPABILITY_NOT_VPN)) {
                 Log.w(TAG, "VPN network is active, null activeNetwork");
                 activeNetwork = null;
             }
             final Resolver resolver = new Resolver(activeNetwork, connectivityManager.getLinkProperties(activeNetwork));
+
             dnsRetry: for (int i = 0; i < DNS_RESOLUTION_RETRIES; ++i) {
                 // Pre-resolve IPs so they're cached when building the userspace string
                 for (final Peer peer : config.getPeers()) {
@@ -495,9 +502,13 @@ public final class GoBackend implements Backend {
             for (final String includedApplication : config.getInterface().getIncludedApplications())
                 builder.addAllowedApplication(includedApplication);
 
-            for (final InetNetwork addr : config.getInterface().getAddresses())
-                builder.addAddress(addr.getAddress(), addr.getMask());
-
+            if (addresses.size() > 0) {
+                for (final InetNetwork addr : addresses)
+                    builder.addAddress(addr.getAddress(), addr.getMask());
+            } else {
+                for (final InetNetwork addr : config.getInterface().getAddresses())
+                    builder.addAddress(addr.getAddress(), addr.getMask());
+            }
             for (final InetAddress addr : config.getInterface().getDnsServers())
                 builder.addDnsServer(addr.getHostAddress());
 
@@ -547,7 +558,11 @@ public final class GoBackend implements Backend {
                 if (tun == null)
                     throw new BackendException(Reason.TUN_CREATION_ERROR);
                 Log.d(TAG, "Go backend " + wgVersion());
-                currentTunnelHandle = wgTurnOn(tunnel.getName(), tun.detachFd(), goConfig);
+                if (currentTunnelHandle < 0) {
+                    currentTunnelHandle = wgTurnOn(tunnel.getName(), tun.detachFd(), goConfig, this);
+                } else {
+                    wgSetFd(currentTunnelHandle, tun.detachFd());
+                }
             }
             if (currentTunnelHandle < 0)
                 throw new BackendException(Reason.GO_ACTIVATION_ERROR_CODE, currentTunnelHandle);
@@ -560,6 +575,35 @@ public final class GoBackend implements Backend {
 
             NetworkRequest req = new NetworkRequest.Builder().addCapability(NetworkCapabilities.NET_CAPABILITY_NOT_VPN).build();
             connectivityManager.requestNetwork(req,  myNetworkCallback);
+        }
+    }
+
+    private void setStateInternal(final Tunnel tunnel, @Nullable final Config config, final State state)
+            throws Exception {
+        Log.i(TAG, "Bringing tunnel " + tunnel.getName() + ' ' + state);
+
+        if (state == State.UP) {
+            if (config == null)
+                throw new BackendException(Reason.TUNNEL_MISSING_CONFIG);
+
+            if (currentTunnelHandle != -1) {
+                Log.w(TAG, "Tunnel already up");
+                return;
+            }
+
+            if (false) {
+                setStateInternalFinalize(tunnel, config, null);
+            } else {
+                // Build config
+                final String goConfig = config.toWgUserspaceString();
+
+                currentTunnelHandle = wgTurnOnDhcp(tunnel.getName(), goConfig, this);
+                if (currentTunnelHandle < 0)
+                    throw new BackendException(Reason.GO_ACTIVATION_ERROR_CODE, currentTunnelHandle);
+
+                currentTunnel = tunnel;
+                currentConfig = config;
+            }
         } else {
             if (currentTunnelHandle == -1) {
                 Log.w(TAG, "Tunnel already down");
@@ -578,6 +622,46 @@ public final class GoBackend implements Backend {
         tunnel.onStateChange(state);
     }
 
+    public void onEvent(String event) {
+        boolean isEvent = false;
+        Set<InetNetwork> addresses = new LinkedHashSet<>();
+
+        Log.d(TAG, "onEvent: " + event);
+        for (final String line : event.split("\\n")) {
+            final String[] params = line.split("=", 2);
+            if (params.length != 2)
+                break;
+
+            final String key = params[0];
+            final String value = params[1];
+
+            if ("event".equals(key)) {
+                isEvent = true;
+            } else if (!isEvent) {
+                break;
+            }
+
+            if ("address".equals(key)) {
+                for (final String strAddr : value.split(",")) {
+                    try {
+                        InetNetwork addr = InetNetwork.parse(strAddr);
+                        if (addr.getMask() < 33 || addr.getMask() == 128)
+                            addresses.add(addr);
+                    } catch(final ParseException ignored) {
+                    }
+                }
+            }
+        }
+
+        if (addresses.size() > 0) {
+            try {
+                setStateInternalFinalize(currentTunnel, currentConfig, addresses);
+            } catch (final Exception e) {
+                Log.d(TAG, "setStateInternalFinalize", e);
+            }
+        }
+    }
+
     /**
      * Callback for {@link GoBackend} that is invoked when {@link VpnService} is started by the
      * system's Always-On VPN mode.
@@ -691,3 +775,7 @@ public final class GoBackend implements Backend {
         }
     }
 }
+
+interface EventHandler {
+    public void onEvent(String event);
+}
diff --git a/tunnel/src/main/java/com/wireguard/android/backend/WgQuickBackend.java b/tunnel/src/main/java/com/wireguard/android/backend/WgQuickBackend.java
index d0dc6a46..06a4db86 100644
--- a/tunnel/src/main/java/com/wireguard/android/backend/WgQuickBackend.java
+++ b/tunnel/src/main/java/com/wireguard/android/backend/WgQuickBackend.java
@@ -58,6 +58,12 @@ public final class WgQuickBackend implements Backend {
     }
 
     @Override
+    public DhcpInfo getDhcpInfo(final Tunnel tunnel) {
+        final DhcpInfo info = new DhcpInfo();
+	return info;
+    }
+
+    @Override
     public Set<String> getRunningTunnelNames() {
         final List<String> output = new ArrayList<>();
         // Don't throw an exception here or nothing will show up in the UI.
diff --git a/tunnel/tools/libwg-go/api-android.go b/tunnel/tools/libwg-go/api-android.go
index 0ab80be9..619dfccd 100644
--- a/tunnel/tools/libwg-go/api-android.go
+++ b/tunnel/tools/libwg-go/api-android.go
@@ -7,10 +7,13 @@ package main
 
 // #cgo LDFLAGS: -llog
 // #include <android/log.h>
+// extern void wgOnEvent(void *eventHandler, const char *event);
 import "C"
 
 import (
+	"context"
 	"fmt"
+	"log"
 	"math"
 	"net"
 	"os"
@@ -25,6 +28,16 @@ import (
 	"golang.zx2c4.com/wireguard/device"
 	"golang.zx2c4.com/wireguard/ipc"
 	"golang.zx2c4.com/wireguard/tun"
+	"golang.zx2c4.com/wireguard/tun/netstack"
+	"golang.zx2c4.com/wireguard/tun/netstack/ipvlan"
+
+	"gvisor.dev/gvisor/pkg/tcpip"
+	"gvisor.dev/gvisor/pkg/tcpip/link/fdbased"
+	"gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
+	"gvisor.dev/gvisor/pkg/tcpip/network/ipv6"
+	"gvisor.dev/gvisor/pkg/tcpip/stack"
+	"gvisor.dev/gvisor/pkg/tcpip/transport/tcp"
+	"gvisor.dev/gvisor/pkg/tcpip/transport/udp"
 )
 
 type AndroidLogger struct {
@@ -49,8 +62,14 @@ type TunnelHandle struct {
 	device *device.Device
 	uapi   net.Listener
 	logger *device.Logger
+	eventHandler unsafe.Pointer
+	cancel context.CancelFunc
+	master *ipvlan.IPVLANMaster
+	//	tunEP *stack.LinkEndpoint
+	tunFd int
 }
 
+var globalStack *stack.Stack
 var tunnelHandles map[int32]TunnelHandle
 
 func GetTunnel(handle int32) (tunnelHandle TunnelHandle, ok bool) {
@@ -60,6 +79,12 @@ func GetTunnel(handle int32) (tunnelHandle TunnelHandle, ok bool) {
 
 func init() {
 	tunnelHandles = make(map[int32]TunnelHandle)
+	opts := stack.Options{
+		NetworkProtocols:   []stack.NetworkProtocolFactory{ipv4.NewProtocol, ipv6.NewProtocol},
+		TransportProtocols: []stack.TransportProtocolFactory{tcp.NewProtocol, udp.NewProtocol},
+		HandleLocal:        true,
+	}
+	globalStack = stack.New(opts)
 	signals := make(chan os.Signal)
 	signal.Notify(signals, unix.SIGUSR2)
 	go func() {
@@ -79,7 +104,7 @@ func init() {
 }
 
 //export wgTurnOn
-func wgTurnOn(interfaceName string, tunFd int32, settings string) int32 {
+func wgTurnOn(interfaceName string, tunFd int32, settings string, eventHandler unsafe.Pointer) int32 {
 	tag := cstring("WireGuard/GoBackend/" + interfaceName)
 	logger := &device.Logger{
 		Verbosef: AndroidLogger{level: C.ANDROID_LOG_DEBUG, tag: tag}.Printf,
@@ -148,21 +173,211 @@ func wgTurnOn(interfaceName string, tunFd int32, settings string) int32 {
 		device.Close()
 		return -1
 	}
-	tunnelHandles[i] = TunnelHandle{device: device, uapi: uapi}
+	tunnelHandles[i] = TunnelHandle{device: device, uapi: uapi, eventHandler: eventHandler}
+	logger.Verbosef("Before wgOnEvent %v", eventHandler)
+	C.wgOnEvent(tunnelHandles[i].eventHandler, C.CString("FOOBAR"))
+	C.wgOnEvent(tunnelHandles[i].eventHandler, C.CString("Called wgTurnOn"))
+	logger.Verbosef("After wgOnEvent")
 	return i
 }
 
-//export wgTurnOff
-func wgTurnOff(tunnelHandle int32) {
+func createNetTUNWithStack(stack *stack.Stack, nicID tcpip.NICID, localAddresses []net.IP, dnsServers []net.IP, mtu int) (tun.Device, *netstack.Net, *ipvlan.IPVLANMaster, error) {
+	dev, ep, err := netstack.NewNetTUN(stack, mtu)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+
+	master := ipvlan.NewIPVLANMaster(ep)
+
+	addrs := make([]tcpip.Address, 0, len(localAddresses))
+	for _, addr := range localAddresses {
+		addrs = append(addrs, tcpip.Address(addr))
+	}
+	ipvlanEP := master.NewIPVLAN(addrs)
+
+	tcpipErr := stack.CreateNIC(nicID, ipvlanEP)
+	if tcpipErr != nil {
+		return nil, nil, nil, fmt.Errorf("CreateNIC: %v", tcpipErr)
+	}
+
+	tnet, err := netstack.NewNetAdapter(stack, nicID, localAddresses, dnsServers)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+
+	return dev, tnet, master, nil
+}
+
+//export wgTurnOnDhcp
+func wgTurnOnDhcp(interfaceName string, settings string, eventHandler unsafe.Pointer) int32 {
+	tag := cstring("WireGuard/GoBackend/" + interfaceName)
+	logger := &device.Logger{
+		Verbosef: AndroidLogger{level: C.ANDROID_LOG_DEBUG, tag: tag}.Printf,
+		Errorf:   AndroidLogger{level: C.ANDROID_LOG_ERROR, tag: tag}.Printf,
+	}
+
+	stack := globalStack
+
+	// FIXME IP address
+	ipStr := "fe80::101"
+	// FIXME name
+	name := "wg0"
+	var tundev tun.Device
+	var tnet *netstack.Net
+	tundev, tnet, master, err := createNetTUNWithStack(
+		stack,
+		1,
+		[]net.IP{net.ParseIP(ipStr)},
+		//                []net.IP{net.ParseIP("fe80::1")},
+		[]net.IP{net.ParseIP("fe80::1")},
+		1420)
+	if err != nil {
+		log.Panic(err)
+	}
+
+	logger.Verbosef("Attaching to netstack interface")
+	device := device.NewDevice(tundev, conn.NewStdNetBind(), logger)
+
+	err = device.IpcSet(settings)
+	if err != nil {
+		logger.Errorf("IpcSet: %v", err)
+		return -1
+	}
+	device.DisableSomeRoamingForBrokenMobileSemantics()
+
+	var uapi net.Listener
+
+	uapiFile, err := ipc.UAPIOpen(name)
+	if err != nil {
+		logger.Errorf("UAPIOpen: %v", err)
+	} else {
+		uapi, err = ipc.UAPIListen(name, uapiFile)
+		if err != nil {
+			uapiFile.Close()
+			logger.Errorf("UAPIListen: %v", err)
+		} else {
+			go func() {
+				for {
+					conn, err := uapi.Accept()
+					if err != nil {
+						return
+					}
+					go device.IpcHandle(conn)
+				}
+			}()
+		}
+	}
+
+	err = device.Up()
+	if err != nil {
+		logger.Errorf("Unable to bring up device: %v", err)
+		uapiFile.Close()
+		device.Close()
+		return -1
+	}
+	logger.Verbosef("Device started")
+
+	var i int32
+	for i = 0; i < math.MaxInt32; i++ {
+		if _, exists := tunnelHandles[i]; !exists {
+			break
+		}
+	}
+	if i == math.MaxInt32 {
+		logger.Errorf("Unable to find empty handle")
+		uapiFile.Close()
+		device.Close()
+		return -1
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+
+	tunnelHandles[i] = TunnelHandle{device: device, uapi: uapi, eventHandler: eventHandler, cancel: cancel, master: master}
+
+	go func(ctx context.Context) {
+		logger.Verbosef("Start dhcp client")
+		src, err := net.ResolveUDPAddr("udp6", fmt.Sprintf("[%s%%1]:546", ipStr))
+		if err != nil {
+			logger.Errorf("ResolveUDPAddr: %v", err)
+			return
+		}
+
+		var dst *net.UDPAddr
+		dst = nil
+
+		conn, err := tnet.DialUDP(src, dst)
+		if err != nil {
+			logger.Errorf("DialUDP: %v", err)
+			return
+		}
+
+		logger.Verbosef("Conn: %v %v %v", src, dst, conn)
+		hwAddr := []byte("   101")
+		addrs, err := netstack.RunDhcp(ctx, conn, hwAddr)
+
+		if err != nil {
+			logger.Errorf("DHCP: %v", err)
+			return
+		}
+
+		msg := ""
+
+		logger.Verbosef("DHCP finished")
+		for _, addr := range addrs {
+			logger.Verbosef("Address: %v", addr)
+			if msg == "" {
+				msg = "event=1\naddress=" + addr.String()
+			} else {
+				msg += "," + addr.String()
+			}
+		}
+
+		C.wgOnEvent(tunnelHandles[i].eventHandler, C.CString(msg))
+	}(ctx)
+
+	logger.Verbosef("Before wgOnEvent %v", eventHandler)
+	C.wgOnEvent(tunnelHandles[i].eventHandler, C.CString("FOOBAR"))
+	C.wgOnEvent(tunnelHandles[i].eventHandler, C.CString("Called wgTurnOn"))
+	logger.Verbosef("After wgOnEvent")
+	return i
+}
+
+//export wgSetFd
+func wgSetFd(tunnelHandle int32, tunFd int32) {
 	handle, ok := tunnelHandles[tunnelHandle]
 	if !ok {
 		return
 	}
+
+	// FIXME MTU
+	var mtu uint32 = 1280
+	tunEP, err := fdbased.New(&fdbased.Options{FDs: []int{int(tunFd)}, MTU: mtu})
+	if err != nil {
+		log.Fatal(err)
+	}
+	handle.tunFd = int(tunFd)
+	handle.master.SetIntEP(tunEP)
+}
+
+//export wgTurnOff
+func wgTurnOff(tunnelHandle int32) unsafe.Pointer {
+	handle, ok := tunnelHandles[tunnelHandle]
+	if !ok {
+		return nil
+	}
+	if handle.master != nil {
+		globalStack.RemoveNIC(1)
+		handle.master.SetIntEP(nil)
+		unix.Close(handle.tunFd)
+	}
+
+	eventHandler := handle.eventHandler
+	C.wgOnEvent(handle.eventHandler, C.CString("Called wgTurnOff"))
 	delete(tunnelHandles, tunnelHandle)
 	if handle.uapi != nil {
 		handle.uapi.Close()
 	}
 	handle.device.Close()
+	return eventHandler
 }
 
 //export wgGetSocketV4
@@ -171,6 +386,7 @@ func wgGetSocketV4(tunnelHandle int32) int32 {
 	if !ok {
 		return -1
 	}
+	C.wgOnEvent(handle.eventHandler, C.CString("Called wgGetSocketV4"))
 	bind, _ := handle.device.Bind().(conn.PeekLookAtSocketFd)
 	if bind == nil {
 		return -1
@@ -188,6 +404,7 @@ func wgGetSocketV6(tunnelHandle int32) int32 {
 	if !ok {
 		return -1
 	}
+	C.wgOnEvent(handle.eventHandler, C.CString("Called wgGetSocketV6"))
 	bind, _ := handle.device.Bind().(conn.PeekLookAtSocketFd)
 	if bind == nil {
 		return -1
diff --git a/tunnel/tools/libwg-go/go.mod b/tunnel/tools/libwg-go/go.mod
index 49fe3780..d9ee9e25 100644
--- a/tunnel/tools/libwg-go/go.mod
+++ b/tunnel/tools/libwg-go/go.mod
@@ -19,3 +19,5 @@ require (
 	golang.zx2c4.com/wintun v0.0.0-20211104114900-415007cec224 // indirect
 	google.golang.org/genproto v0.0.0-20210722135532-667f2b7c528f // indirect
 )
+
+replace golang.zx2c4.com/wireguard/tun/netstack => golang.m7n.se/wireguard/tun/netstack v0.0.0-20210315192121-e7c9dcf39d3f
diff --git a/tunnel/tools/libwg-go/jni.c b/tunnel/tools/libwg-go/jni.c
index 121729a7..5dd20ed2 100644
--- a/tunnel/tools/libwg-go/jni.c
+++ b/tunnel/tools/libwg-go/jni.c
@@ -3,40 +3,105 @@
  * Copyright © 2017-2021 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
  */
 
+#include <assert.h>
 #include <jni.h>
 #include <stdlib.h>
 #include <string.h>
+#include <android/log.h>
+
+#define TAG "WireGuard/GoBackend"
 
 struct go_string { const char *str; long n; };
-extern int wgTurnOn(struct go_string ifname, int tun_fd, struct go_string settings);
-extern void wgTurnOff(int handle);
+extern int wgTurnOn(struct go_string ifname, int tun_fd, struct go_string settings, void *eventHandler);
+extern int wgTurnOnDhcp(struct go_string ifname, struct go_string settings, void *eventHandler);
+extern void wgSetFd(int handle, int tun_fd);
+extern void *wgTurnOff(int handle);
 extern int wgGetSocketV4(int handle);
 extern int wgGetSocketV6(int handle);
 extern char *wgGetConfig(int handle);
 extern char *wgVersion();
 extern int wgStartGrpc();
+extern void wgOnEvent(void *eventHandler, const char *event);
+
+static JavaVM *gVm;
+static jclass gEventHandlerClass;
+static jmethodID gOnEventMethod;
 
-JNIEXPORT jint JNICALL Java_com_wireguard_android_backend_GoBackend_wgTurnOn(JNIEnv *env, jclass c, jstring ifname, jint tun_fd, jstring settings)
+JNIEXPORT jint JNI_OnLoad(JavaVM *vm, void *reserved)
+{
+	JNIEnv* env;
+	char buf[128];
+
+	__android_log_write(ANDROID_LOG_ERROR, TAG, "JNI_OnLoad");
+
+	gVm = vm;
+	if ((*vm)->GetEnv(vm, (void**)&env, JNI_VERSION_1_6) != JNI_OK) {
+		__android_log_write(ANDROID_LOG_ERROR, TAG, "GetEnv error");
+		return JNI_ERR;
+	}
+
+	sprintf(buf, "GetEnv FindClass %p", (*env)->FindClass);
+	__android_log_write(ANDROID_LOG_ERROR, TAG, buf);
+	gEventHandlerClass = (*env)->FindClass(env, "com/wireguard/android/backend/EventHandler");
+	sprintf(buf, "gEventHandlerClass %p", gEventHandlerClass);
+	__android_log_write(ANDROID_LOG_ERROR, TAG, buf);
+
+	gOnEventMethod = (*env)->GetMethodID(env, gEventHandlerClass, "onEvent", "(Ljava/lang/String;)V");
+	sprintf(buf, "gOnEventMethod %p", gOnEventMethod);
+	__android_log_write(ANDROID_LOG_ERROR, TAG, buf);
+	//assert(gOnEventMethod);
+
+	return JNI_VERSION_1_6;
+}
+
+JNIEXPORT jint JNICALL Java_com_wireguard_android_backend_GoBackend_wgTurnOn(JNIEnv *env, jclass c, jstring ifname, jint tun_fd, jstring settings, jobject eventHandler)
 {
 	const char *ifname_str = (*env)->GetStringUTFChars(env, ifname, 0);
 	size_t ifname_len = (*env)->GetStringUTFLength(env, ifname);
 	const char *settings_str = (*env)->GetStringUTFChars(env, settings, 0);
 	size_t settings_len = (*env)->GetStringUTFLength(env, settings);
+	jobject event_handler = (*env)->NewGlobalRef(env, eventHandler);
 	int ret = wgTurnOn((struct go_string){
 		.str = ifname_str,
 		.n = ifname_len
 	}, tun_fd, (struct go_string){
 		.str = settings_str,
 		.n = settings_len
-	});
+	}, event_handler);
 	(*env)->ReleaseStringUTFChars(env, ifname, ifname_str);
 	(*env)->ReleaseStringUTFChars(env, settings, settings_str);
 	return ret;
 }
 
+JNIEXPORT jint JNICALL Java_com_wireguard_android_backend_GoBackend_wgTurnOnDhcp(JNIEnv *env, jclass c, jstring ifname, jstring settings, jobject eventHandler)
+{
+	const char *ifname_str = (*env)->GetStringUTFChars(env, ifname, 0);
+	size_t ifname_len = (*env)->GetStringUTFLength(env, ifname);
+	const char *settings_str = (*env)->GetStringUTFChars(env, settings, 0);
+	size_t settings_len = (*env)->GetStringUTFLength(env, settings);
+	jobject event_handler = (*env)->NewGlobalRef(env, eventHandler);
+	int ret = wgTurnOnDhcp((struct go_string){
+		.str = ifname_str,
+		.n = ifname_len
+	}, (struct go_string){
+		.str = settings_str,
+		.n = settings_len
+	}, event_handler);
+	(*env)->ReleaseStringUTFChars(env, ifname, ifname_str);
+	(*env)->ReleaseStringUTFChars(env, settings, settings_str);
+	return ret;
+}
+
+JNIEXPORT void JNICALL Java_com_wireguard_android_backend_GoBackend_wgSetFd(JNIEnv *env, jclass c, jint handle, jint tun_fd)
+{
+	wgSetFd(handle, tun_fd);
+}
+
 JNIEXPORT void JNICALL Java_com_wireguard_android_backend_GoBackend_wgTurnOff(JNIEnv *env, jclass c, jint handle)
 {
-	wgTurnOff(handle);
+	jobject event_handler = wgTurnOff(handle);
+	if (event_handler)
+		(*env)->DeleteGlobalRef(env, event_handler);
 }
 
 JNIEXPORT jint JNICALL Java_com_wireguard_android_backend_GoBackend_wgGetSocketV4(JNIEnv *env, jclass c, jint handle)
@@ -82,3 +147,29 @@ JNIEXPORT jint JNICALL Java_com_wireguard_android_backend_GoBackend_wgStartGrpc(
 	(*env)->ReleaseStringUTFChars(env, sockname, sockname_str);
 	return res;
 }
+
+void wgOnEvent(void *eventHandler, const char *event)
+{
+	JavaVMAttachArgs attachArgs = { JNI_VERSION_1_6, NULL, NULL };
+	jobject jEventHandler = eventHandler;
+	JNIEnv *env;
+	char buf[128];
+
+	__android_log_write(ANDROID_LOG_ERROR, TAG, "wgOnEvent enter 2");
+	jint rs = (*gVm)->AttachCurrentThread(gVm, &env, &attachArgs);
+
+	sprintf(buf, "AttachCurrentThread %i %p", rs, env);
+	__android_log_write(ANDROID_LOG_ERROR, TAG, buf);
+	assert (rs == JNI_OK);
+	jstring jevent = (*env)->NewStringUTF(env, event);
+	sprintf(buf, "NewStringUTF %p", jevent);
+	__android_log_write(ANDROID_LOG_ERROR, TAG, buf);
+	//free(event);
+	sprintf(buf, "CallVoidMethod %p %p %p %p", env, jEventHandler, gOnEventMethod, jevent);
+	__android_log_write(ANDROID_LOG_ERROR, TAG, buf);
+	(*env)->CallVoidMethod(env, jEventHandler, gOnEventMethod, jevent);
+	/* sprintf(buf, "CallVoidMethod"); */
+	/* __android_log_write(ANDROID_LOG_ERROR, TAG, buf); */
+	// TODO free jevent?
+	__android_log_write(ANDROID_LOG_ERROR, TAG, "wgOnEvent end");
+}
diff --git a/ui/src/main/java/com/wireguard/android/fragment/TunnelDetailFragment.kt b/ui/src/main/java/com/wireguard/android/fragment/TunnelDetailFragment.kt
index fad1b5d4..f2cf9040 100644
--- a/ui/src/main/java/com/wireguard/android/fragment/TunnelDetailFragment.kt
+++ b/ui/src/main/java/com/wireguard/android/fragment/TunnelDetailFragment.kt
@@ -104,6 +104,10 @@ class TunnelDetailFragment : BaseFragment() {
         lastState = state
         var now = LocalDateTime.now(ZoneId.of("UTC"))
         try {
+            binding.dhcpInfoText.text = tunnel.getDhcpInfo().get()
+            binding.dhcpInfoLabel.visibility = View.VISIBLE
+            binding.dhcpInfoText.visibility = View.VISIBLE
+
             val statistics = tunnel.getStatisticsAsync()
             for (i in 0 until binding.peersLayout.childCount) {
                 val peer: TunnelDetailPeerBinding = DataBindingUtil.getBinding(binding.peersLayout.getChildAt(i))
diff --git a/ui/src/main/java/com/wireguard/android/model/ObservableTunnel.kt b/ui/src/main/java/com/wireguard/android/model/ObservableTunnel.kt
index 252e8759..edf8feaf 100644
--- a/ui/src/main/java/com/wireguard/android/model/ObservableTunnel.kt
+++ b/ui/src/main/java/com/wireguard/android/model/ObservableTunnel.kt
@@ -8,6 +8,7 @@ import android.util.Log
 import androidx.databinding.BaseObservable
 import androidx.databinding.Bindable
 import com.wireguard.android.BR
+import com.wireguard.android.backend.DhcpInfo
 import com.wireguard.android.backend.Statistics
 import com.wireguard.android.backend.Tunnel
 import com.wireguard.android.databinding.Keyed
@@ -136,6 +137,35 @@ class ObservableTunnel internal constructor(
         return statistics
     }
 
+    @get:Bindable
+    var dhcpInfo: DhcpInfo? = null
+        get() {
+            if (field == null || field?.isStale != false)
+                applicationScope.launch {
+                    try {
+                        manager.getTunnelDhcpInfo(this@ObservableTunnel)
+                    } catch (e: Throwable) {
+                        Log.e(TAG, Log.getStackTraceString(e))
+                    }
+                }
+            return field
+        }
+        private set
+
+    suspend fun getDhcpInfo(): DhcpInfo = withContext(Dispatchers.Main.immediate) {
+        dhcpInfo.let {
+            if (it == null || it.isStale)
+                manager.getTunnelDhcpInfo(this@ObservableTunnel)
+            else
+                it
+        }
+    }
+
+    fun onDhcpInfoChanged(dhcpInfo: DhcpInfo?): DhcpInfo? {
+        this.dhcpInfo = dhcpInfo
+        notifyPropertyChanged(BR.dhcpInfo)
+        return dhcpInfo
+    }
 
     suspend fun deleteAsync() = manager.delete(this)
 
diff --git a/ui/src/main/java/com/wireguard/android/model/TunnelManager.kt b/ui/src/main/java/com/wireguard/android/model/TunnelManager.kt
index ec796164..ac39ac4a 100644
--- a/ui/src/main/java/com/wireguard/android/model/TunnelManager.kt
+++ b/ui/src/main/java/com/wireguard/android/model/TunnelManager.kt
@@ -17,6 +17,7 @@ import com.wireguard.android.Application.Companion.getBackend
 import com.wireguard.android.Application.Companion.getTunnelManager
 import com.wireguard.android.BR
 import com.wireguard.android.R
+import com.wireguard.android.backend.DhcpInfo
 import com.wireguard.android.backend.Statistics
 import com.wireguard.android.backend.Tunnel
 import com.wireguard.android.configStore.ConfigStore
@@ -240,6 +241,10 @@ class TunnelManager(private val configStore: ConfigStore) : BaseObservable() {
         }
     }
 
+    suspend fun getTunnelDhcpInfo(tunnel: ObservableTunnel): DhcpInfo = withContext(Dispatchers.Main.immediate) {
+        tunnel.onDhcpInfoChanged(withContext(Dispatchers.IO) { getBackend().getDhcpInfo(tunnel) })!!
+    }
+
     suspend fun getTunnelState(tunnel: ObservableTunnel): Tunnel.State = withContext(Dispatchers.Main.immediate) {
         tunnel.onStateChanged(withContext(Dispatchers.IO) { getBackend().getState(tunnel) })
     }
diff --git a/ui/src/main/res/layout/tunnel_detail_fragment.xml b/ui/src/main/res/layout/tunnel_detail_fragment.xml
index aef71e18..c004fc5a 100644
--- a/ui/src/main/res/layout/tunnel_detail_fragment.xml
+++ b/ui/src/main/res/layout/tunnel_detail_fragment.xml
@@ -322,14 +322,42 @@
                         android:layout_height="wrap_content"
                         android:contentDescription="@string/applications"
                         android:nextFocusUp="@id/mtu_text"
-                        android:nextFocusDown="@id/peers_layout"
-                        android:nextFocusForward="@id/peers_layout"
+                        android:nextFocusDown="@id/dhcp_info_text"
+                        android:nextFocusForward="@id/dhcp_info_text"
                         android:onClick="@{ClipboardUtils::copyTextView}"
                         android:text="@{config.interface.includedApplications.isEmpty() ? @plurals/n_excluded_applications(config.interface.excludedApplications.size(), config.interface.excludedApplications.size()) : @plurals/n_included_applications(config.interface.includedApplications.size(), config.interface.includedApplications.size())}"
                         android:visibility="@{config.interface.includedApplications.isEmpty() &amp;&amp; config.interface.excludedApplications.isEmpty() ? android.view.View.GONE : android.view.View.VISIBLE}"
                         app:layout_constraintTop_toBottomOf="@+id/applications_label"
                         app:layout_constraintStart_toStartOf="parent"
                         tools:text="8 excluded" />
+
+                    <TextView
+                        android:id="@+id/dhcp_info_label"
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:layout_marginTop="8dp"
+                        android:labelFor="@+id/dhcp_info_text"
+                        android:text="@string/dhcp_info"
+                        android:visibility="gone"
+                        app:layout_constraintStart_toStartOf="parent"
+                        app:layout_constraintTop_toBottomOf="@id/applications_text" />
+
+                    <TextView
+                        android:id="@+id/dhcp_info_text"
+                        style="@style/DetailText"
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:contentDescription="@string/dhcp_info"
+                        android:nextFocusUp="@id/applications_text"
+                        android:nextFocusDown="@id/peers_layout"
+                        android:nextFocusForward="@id/peers_layout"
+                        android:onClick="@{ClipboardUtils::copyTextView}"
+                        android:visibility="gone"
+                        app:layout_constraintStart_toStartOf="parent"
+                        app:layout_constraintTop_toBottomOf="@+id/dhcp_info_label"
+                        tools:text="Addresses: 192.0.2.123/24, 2001:db8::123/128"
+                        tools:visibility="visible" />
+
                 </androidx.constraintlayout.widget.ConstraintLayout>
             </com.google.android.material.card.MaterialCardView>
 
diff --git a/ui/src/main/res/values/strings.xml b/ui/src/main/res/values/strings.xml
index 3b32ab79..4da4e8fe 100644
--- a/ui/src/main/res/values/strings.xml
+++ b/ui/src/main/res/values/strings.xml
@@ -248,4 +248,6 @@
     <string name="biometric_prompt_private_key_title">Authenticate to view private key</string>
     <string name="biometric_auth_error">Authentication failure</string>
     <string name="biometric_auth_error_reason">Authentication failure: %s</string>
+    <string name="dhcp_info">DHCP information</string>
+    <string name="dhcp_info_text">Addresses: %s\nIPv6 prefixes: %s\nDNS servers: %s</string>
 </resources>