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Code Issues Releases Wiki Activity

Add MDNS discovery

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Uses Android's `NsdManager` to announce a `_kdeconnect._udp` service using MDNS. This is done in addition to sending UDP broadcasts.

When we detect a device this way, we send a UDP identity packet to it (identical to the ones we broadcast but sent to a single device).

I also added a toggle in settings to disable the UDP broadcasts, so we can test MDNS by itself.
This commit is contained in:
Albert Vaca Cintora 2023-08-28 21:37:55 +00:00 committed by Weixuan Xiao
parent b545257fa7
commit 8f8a09a99a
8 changed files with 411 additions and 49 deletions
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2
res/values/strings.xml
View File

@ -547,4 +547,6 @@ SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted
<string name="plugin_stats">Plugin stats</string>
<string name="enable_udp_broadcast">Enable UDP device discovery</string>
</resources>

31
src/org/kde/kdeconnect/Backends/LanBackend/LanLinkProvider.java
View File

@ -25,6 +25,7 @@ import org.kde.kdeconnect.Helpers.TrustedNetworkHelper;
import org.kde.kdeconnect.KdeConnect;
import org.kde.kdeconnect.NetworkPacket;
import org.kde.kdeconnect.UserInterface.CustomDevicesActivity;
import org.kde.kdeconnect.UserInterface.SettingsFragment;
import java.io.BufferedReader;
import java.io.IOException;
@ -58,9 +59,9 @@ import kotlin.text.Charsets;
*/
public class LanLinkProvider extends BaseLinkProvider {
private final static int UDP_PORT = 1716;
private final static int MIN_PORT = 1716;
private final static int MAX_PORT = 1764;
final static int UDP_PORT = 1716;
final static int MIN_PORT = 1716;
final static int MAX_PORT = 1764;
final static int PAYLOAD_TRANSFER_MIN_PORT = 1739;
final static int MAX_UDP_PACKET_SIZE = 1024 * 512;
@ -69,13 +70,15 @@ public class LanLinkProvider extends BaseLinkProvider {
private final Context context;
private final HashMap<String, LanLink> visibleDevices = new HashMap<>(); //Links by device id
final HashMap<String, LanLink> visibleDevices = new HashMap<>(); //Links by device id
final ConcurrentHashMap<String, Long> lastConnectionTime = new ConcurrentHashMap<>();
private ServerSocket tcpServer;
private DatagramSocket udpServer;
private MdnsDiscovery mdnsDiscovery;
private long lastBroadcast = 0;
private final static long delayBetweenBroadcasts = 200;
@ -265,6 +268,7 @@ public class LanLinkProvider extends BaseLinkProvider {
public LanLinkProvider(Context context) {
this.context = context;
this.mdnsDiscovery = new MdnsDiscovery(context, this);
}
private void setupUdpListener() {
@ -352,11 +356,11 @@ public class LanLinkProvider extends BaseLinkProvider {
}
private void broadcastUdpIdentityPacket() {
if (System.currentTimeMillis() < lastBroadcast + delayBetweenBroadcasts) {
Log.i("LanLinkProvider", "broadcastUdpPacket: relax cowboy");
SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
if (!preferences.getBoolean(SettingsFragment.KEY_UDP_BROADCAST_ENABLED, true)) {
Log.i("LanLinkProvider", "UDP broadcast is disabled in settings. Skipping.");
return;
}
lastBroadcast = System.currentTimeMillis();
ThreadHelper.execute(() -> {
List<String> ipStringList = CustomDevicesActivity
@ -436,19 +440,32 @@ public class LanLinkProvider extends BaseLinkProvider {
setupUdpListener();
setupTcpListener();
mdnsDiscovery.startDiscovering();
mdnsDiscovery.startAnnouncing();
broadcastUdpIdentityPacket();
}
}
@Override
public void onNetworkChange() {
if (System.currentTimeMillis() < lastBroadcast + delayBetweenBroadcasts) {
Log.i("LanLinkProvider", "onNetworkChange: relax cowboy");
return;
}
lastBroadcast = System.currentTimeMillis();
broadcastUdpIdentityPacket();
mdnsDiscovery.stopDiscovering();
mdnsDiscovery.startDiscovering();
}
@Override
public void onStop() {
//Log.i("KDE/LanLinkProvider", "onStop");
listening = false;
mdnsDiscovery.stopAnnouncing();
mdnsDiscovery.stopDiscovering();
try {
tcpServer.close();
} catch (Exception e) {

224
src/org/kde/kdeconnect/Backends/LanBackend/MdnsDiscovery.java Normal file
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@ -0,0 +1,224 @@
/*
* SPDX-FileCopyrightText: 2023 Albert Vaca Cintora <albertvaka@gmail.com>
*
* SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
*/
package org.kde.kdeconnect.Backends.LanBackend;
import android.content.Context;
import android.net.nsd.NsdManager;
import android.net.nsd.NsdServiceInfo;
import android.net.wifi.WifiManager;
import android.util.Log;
import org.kde.kdeconnect.Helpers.DeviceHelper;
import java.net.InetAddress;
import java.util.Collections;
public class MdnsDiscovery {
static final String LOG_TAG = "MdnsDiscovery";
static final String SERVICE_TYPE = "_kdeconnect._udp";
private final Context context;
private final LanLinkProvider lanLinkProvider;
private final NsdManager mNsdManager;
private NsdManager.RegistrationListener registrationListener;
private NsdManager.DiscoveryListener discoveryListener;
private WifiManager.MulticastLock multicastLock;
private NsdResolveQueue mNsdResolveQueue;
public MdnsDiscovery(Context context, LanLinkProvider lanLinkProvider) {
this.context = context;
this.lanLinkProvider = lanLinkProvider;
this.mNsdManager = (NsdManager) context.getSystemService(Context.NSD_SERVICE);
this.mNsdResolveQueue = new NsdResolveQueue(this.mNsdManager);
WifiManager wifiManager = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);
multicastLock = wifiManager.createMulticastLock("kdeConnectMdnsMulticastLock");
}
void startDiscovering() {
if (discoveryListener == null) {
multicastLock.acquire();
discoveryListener = createDiscoveryListener();
mNsdManager.discoverServices(SERVICE_TYPE, NsdManager.PROTOCOL_DNS_SD, discoveryListener);
}
}
void stopDiscovering() {
try {
if (discoveryListener != null) {
mNsdManager.stopServiceDiscovery(discoveryListener);
multicastLock.release();
}
} catch(IllegalArgumentException e) {
// Ignore "listener not registered" exception
}
discoveryListener = null;
}
void stopAnnouncing() {
try {
if (registrationListener != null) {
mNsdManager.unregisterService(registrationListener);
}
} catch(IllegalArgumentException e) {
// Ignore "listener not registered" exception
}
registrationListener = null;
}
void startAnnouncing() {
if (registrationListener == null) {
NsdServiceInfo serviceInfo;
try {
serviceInfo = createNsdServiceInfo();
} catch (IllegalAccessException e) {
Log.w(LOG_TAG, "Couldn't start announcing via MDNS: " + e.getMessage());
return;
}
registrationListener = createRegistrationListener();
mNsdManager.registerService(serviceInfo, NsdManager.PROTOCOL_DNS_SD, registrationListener);
}
}
NsdManager.RegistrationListener createRegistrationListener() {
return new NsdManager.RegistrationListener() {
@Override
public void onServiceRegistered(NsdServiceInfo serviceInfo) {
// If Android changed the service name to avoid conflicts, here we can read it.
Log.i(LOG_TAG, "Registered " + serviceInfo.getServiceName());
}
@Override
public void onRegistrationFailed(NsdServiceInfo serviceInfo, int errorCode) {
Log.e(LOG_TAG, "Registration failed with: " + errorCode);
}
@Override
public void onServiceUnregistered(NsdServiceInfo serviceInfo) {
Log.d(LOG_TAG, "Service unregistered: " + serviceInfo);
}
@Override
public void onUnregistrationFailed(NsdServiceInfo serviceInfo, int errorCode) {
Log.e(LOG_TAG, "Unregister of " + serviceInfo + " failed with: " + errorCode);
}
};
}
public NsdServiceInfo createNsdServiceInfo() throws IllegalAccessException {
NsdServiceInfo serviceInfo = new NsdServiceInfo();
String deviceId = DeviceHelper.getDeviceId(context);
// Without resolving the DNS, the service name is the only info we have so it must be sufficient to identify a device.
// Also, it must be unique, otherwise it will be automatically renamed. For these reasons we use the deviceId.
serviceInfo.setServiceName(deviceId);
serviceInfo.setServiceType(SERVICE_TYPE);
serviceInfo.setPort(LanLinkProvider.UDP_PORT);
// The following fields aren't really used for anything, since we can't include enough info
// for it to be useful (namely: we can't include the device certificate).
// Each field (key + value) needs to be < 255 bytes. All the fields combined need to be < 1300 bytes.
// Also, on Android Lollipop those fields aren't resolved.
String deviceName = DeviceHelper.getDeviceName(context);
String deviceType = DeviceHelper.getDeviceType(context).toString();
String protocolVersion = Integer.toString(DeviceHelper.ProtocolVersion);
serviceInfo.setAttribute("id", deviceId);
serviceInfo.setAttribute("name", deviceName);
serviceInfo.setAttribute("type", deviceType);
serviceInfo.setAttribute("protocol", protocolVersion);
Log.i(LOG_TAG, "My MDNS info: " + serviceInfo);
return serviceInfo;
}
NsdManager.DiscoveryListener createDiscoveryListener() {
return new NsdManager.DiscoveryListener() {
final String myId = DeviceHelper.getDeviceId(context);
@Override
public void onDiscoveryStarted(String serviceType) {
Log.i(LOG_TAG, "Service discovery started: " + serviceType);
}
@Override
public void onServiceFound(NsdServiceInfo serviceInfo) {
Log.d(LOG_TAG, "Service discovered: " + serviceInfo);
String deviceId = serviceInfo.getServiceName();
if (myId.equals(deviceId)) {
Log.d(LOG_TAG, "Discovered myself, ignoring.");
return;
}
if (lanLinkProvider.visibleDevices.containsKey(deviceId)) {
Log.i(LOG_TAG, "MDNS discovered " + deviceId + " to which I'm already connected to. Ignoring.");
return;
}
// We use a queue because only one service can be resolved at
// a time, otherwise we get error 3 (already active) in onResolveFailed.
mNsdResolveQueue.resolveOrEnqueue(serviceInfo, createResolveListener());
}
@Override
public void onServiceLost(NsdServiceInfo serviceInfo) {
Log.w(LOG_TAG, "Service lost: " + serviceInfo);
// We can't see this device via mdns. This probably means it's not reachable anymore
// but we do nothing here since we have other ways to do detect unreachable devices
// that hopefully will also trigger.
}
@Override
public void onDiscoveryStopped(String serviceType) {
Log.i(LOG_TAG, "MDNS discovery stopped: " + serviceType);
}
@Override
public void onStartDiscoveryFailed(String serviceType, int errorCode) {
Log.e(LOG_TAG, "MDNS discovery start failed: " + errorCode);
}
@Override
public void onStopDiscoveryFailed(String serviceType, int errorCode) {
Log.e(LOG_TAG, "MDNS discovery stop failed: " + errorCode);
}
};
}
/**
* Returns a new listener instance since NsdManager wants a different listener each time you call resolveService
*/
NsdManager.ResolveListener createResolveListener() {
return new NsdManager.ResolveListener() {
@Override
public void onResolveFailed(NsdServiceInfo serviceInfo, int errorCode) {
Log.w(LOG_TAG, "MDNS error " + errorCode + " resolving service: " + serviceInfo);
}
@Override
public void onServiceResolved(NsdServiceInfo serviceInfo) {
Log.i(LOG_TAG, "MDNS successfully resolved " + serviceInfo);
// Let the LanLinkProvider handle the connection
InetAddress remoteAddress = serviceInfo.getHost();
lanLinkProvider.sendUdpIdentityPacket(Collections.singletonList(remoteAddress));
}
};
}
}

91
src/org/kde/kdeconnect/Backends/LanBackend/NsdResolveQueue.java Normal file
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@ -0,0 +1,91 @@
/*
* SPDX-FileCopyrightText: 2023 Albert Vaca Cintora <albertvaka@gmail.com>
*
* SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
*/
package org.kde.kdeconnect.Backends.LanBackend;
import android.net.nsd.NsdManager;
import android.net.nsd.NsdServiceInfo;
import android.util.Log;
import androidx.annotation.NonNull;
import java.util.LinkedList;
public class NsdResolveQueue {
static final String LOG_TAG = "NsdResolveQueue";
final @NonNull NsdManager mNsdManager;
private final Object mLock = new Object();
private final LinkedList<PendingResolve> mResolveRequests = new LinkedList<>();
public NsdResolveQueue(NsdManager nsdManager) {
this.mNsdManager = nsdManager;
}
private static class PendingResolve {
final @NonNull NsdServiceInfo serviceInfo;
final @NonNull NsdManager.ResolveListener listener;
private PendingResolve(@NonNull NsdServiceInfo serviceInfo, @NonNull NsdManager.ResolveListener listener) {
this.serviceInfo = serviceInfo;
this.listener = listener;
}
}
public void resolveOrEnqueue(@NonNull NsdServiceInfo serviceInfo, @NonNull NsdManager.ResolveListener listener) {
synchronized (mLock) {
for (PendingResolve existing : mResolveRequests) {
if (serviceInfo.getServiceName().equals(existing.serviceInfo.getServiceName())) {
Log.i(LOG_TAG, "Not enqueuing a new resolve request for the same service: " + serviceInfo.getServiceName());
return;
}
}
mResolveRequests.addLast(new PendingResolve(serviceInfo, new ListenerWrapper(listener)));
if (mResolveRequests.size() == 1) {
resolveNextRequest();
}
}
}
private class ListenerWrapper implements NsdManager.ResolveListener {
private final @NonNull NsdManager.ResolveListener mListener;
private ListenerWrapper(@NonNull NsdManager.ResolveListener listener) {
mListener = listener;
}
@Override
public void onResolveFailed(NsdServiceInfo serviceInfo, int errorCode) {
mListener.onResolveFailed(serviceInfo, errorCode);
synchronized (mLock) {
mResolveRequests.pop();
resolveNextRequest();
}
}
@Override
public void onServiceResolved(NsdServiceInfo serviceInfo) {
mListener.onServiceResolved(serviceInfo);
synchronized (mLock) {
mResolveRequests.pop();
resolveNextRequest();
}
}
}
private void resolveNextRequest() {
if (!mResolveRequests.isEmpty()) {
PendingResolve request = mResolveRequests.getFirst();
mNsdManager.resolveService(request.serviceInfo, request.listener);
}
}
}

58
src/org/kde/kdeconnect/Helpers/NetworkHelper.kt Normal file
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@ -0,0 +1,58 @@
/*
* SPDX-FileCopyrightText: 2023 Albert Vaca Cintora <albertvaka@gmail.com>
*
* SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
*/
package org.kde.kdeconnect.Helpers
import java.net.Inet4Address
import java.net.InetAddress
import java.net.NetworkInterface
import java.net.SocketException
object NetworkHelper {
//Prefer IPv4 over IPv6, because sshfs doesn't seem to like IPv6
// Anything with rmnet is related to cellular connections or USB
// tethering mechanisms. See:
//
// https://android.googlesource.com/kernel/msm/+/android-msm-flo-3.4-kitkat-mr1/Documentation/usb/gadget_rmnet.txt
//
// If we run across an interface that has this, we can safely
// ignore it. In fact, it's much safer to do. If we don't, we
// might get invalid IP adddresses out of it.
@JvmStatic
val localIpAddress: InetAddress?
get() {
var ip6: InetAddress? = null
try {
for (intf in NetworkInterface.getNetworkInterfaces()) {
// Anything with rmnet is related to cellular connections or USB
// tethering mechanisms. See:
//
// https://android.googlesource.com/kernel/msm/+/android-msm-flo-3.4-kitkat-mr1/Documentation/usb/gadget_rmnet.txt
//
// If we run across an interface that has this, we can safely
// ignore it. In fact, it's much safer to do. If we don't, we
// might get invalid IP adddresses out of it.
if (intf.displayName.contains("rmnet")) {
continue
}
val enumIpAddr = intf.inetAddresses
while (enumIpAddr.hasMoreElements()) {
val inetAddress = enumIpAddr.nextElement()
if (!inetAddress.isLoopbackAddress) {
ip6 =
if (inetAddress is Inet4Address) { //Prefer IPv4 over IPv6, because sshfs doesn't seem to like IPv6
return inetAddress
} else {
inetAddress
}
}
}
}
} catch (ignored: SocketException) {
}
return ip6
}
}

3
src/org/kde/kdeconnect/Plugins/SftpPlugin/SftpPlugin.java
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@ -20,6 +20,7 @@ import androidx.annotation.NonNull;
import org.json.JSONException;
import org.json.JSONObject;
import org.kde.kdeconnect.Helpers.NetworkHelper;
import org.kde.kdeconnect.NetworkPacket;
import org.kde.kdeconnect.Plugins.Plugin;
import org.kde.kdeconnect.Plugins.PluginFactory;
@ -147,7 +148,7 @@ public class SftpPlugin extends Plugin implements SharedPreferences.OnSharedPref
NetworkPacket np2 = new NetworkPacket(PACKET_TYPE_SFTP);
np2.set("ip", server.getLocalIpAddress()); // for backwards compatibility
np2.set("ip", NetworkHelper.getLocalIpAddress().getHostAddress());
np2.set("port", server.getPort());
np2.set("user", SimpleSftpServer.USER);
np2.set("password", server.getPassword());

38
src/org/kde/kdeconnect/Plugins/SftpPlugin/SimpleSftpServer.java
View File

@ -26,17 +26,12 @@ import org.kde.kdeconnect.Helpers.RandomHelper;
import org.kde.kdeconnect.Helpers.SecurityHelpers.RsaHelper;
import java.io.IOException;
import java.net.Inet4Address;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.security.GeneralSecurityException;
import java.security.KeyPair;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.util.Arrays;
import java.util.Collections;
import java.util.Enumeration;
import java.util.List;
class SimpleSftpServer {
@ -145,39 +140,6 @@ class SimpleSftpServer {
return port;
}
String getLocalIpAddress() {
String ip6 = null;
try {
for (Enumeration<NetworkInterface> en = NetworkInterface.getNetworkInterfaces(); en.hasMoreElements(); ) {
NetworkInterface intf = en.nextElement();
// Anything with rmnet is related to cellular connections or USB
// tethering mechanisms. See:
//
// https://android.googlesource.com/kernel/msm/+/android-msm-flo-3.4-kitkat-mr1/Documentation/usb/gadget_rmnet.txt
//
// If we run across an interface that has this, we can safely
// ignore it. In fact, it's much safer to do. If we don't, we
// might get invalid IP adddresses out of it.
if (intf.getDisplayName().contains("rmnet")) continue;
for (Enumeration<InetAddress> enumIpAddr = intf.getInetAddresses(); enumIpAddr.hasMoreElements(); ) {
InetAddress inetAddress = enumIpAddr.nextElement();
if (!inetAddress.isLoopbackAddress()) {
String address = inetAddress.getHostAddress();
if (inetAddress instanceof Inet4Address) { //Prefer IPv4 over IPv6, because sshfs doesn't seem to like IPv6
return address;
} else {
ip6 = address;
}
}
}
}
} catch (SocketException ignored) {
}
return ip6;
}
public boolean isInitialized() {
return initialized;
}

13
src/org/kde/kdeconnect/UserInterface/SettingsFragment.java
View File

@ -37,6 +37,9 @@ import org.kde.kdeconnect_tp.R;
public class SettingsFragment extends PreferenceFragmentCompat {
public static final String KEY_UDP_BROADCAST_ENABLED = "udp_broadcast_enabled";
public static final String KEY_APP_THEME = "theme_pref";
private EditTextPreference renameDevice;
@NonNull
@ -90,7 +93,7 @@ public class SettingsFragment extends PreferenceFragmentCompat {
// Theme Selector
ListPreference themeSelector = new ListPreference(context);
themeSelector.setKey("theme_pref");
themeSelector.setKey(KEY_APP_THEME);
themeSelector.setTitle(R.string.theme_dialog_title);
themeSelector.setDialogTitle(R.string.theme_dialog_title);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {
@ -168,6 +171,12 @@ public class SettingsFragment extends PreferenceFragmentCompat {
return true;
});
// UDP broadcast toggle
final TwoStatePreference udpBroadcastDiscovery = new SwitchPreference(context);
udpBroadcastDiscovery.setDefaultValue(true);
udpBroadcastDiscovery.setKey(KEY_UDP_BROADCAST_ENABLED);
udpBroadcastDiscovery.setTitle(R.string.enable_udp_broadcast);
screen.addPreference(udpBroadcastDiscovery);
// More settings text
Preference moreSettingsText = new Preference(context);
@ -178,7 +187,5 @@ public class SettingsFragment extends PreferenceFragmentCompat {
screen.addPreference(moreSettingsText);
setPreferenceScreen(screen);
}
}