cmd/tailscale,java: implement file sharing

Fixes tailscale/tailscale#1809

Signed-off-by: Elias Naur <mail@eliasnaur.com>

android/src/main/AndroidManifest.xml

@@ -9,7 +9,7 @@
 
 	<application android:label="Tailscale" android:icon="@mipmap/ic_launcher" android:roundIcon="@mipmap/ic_launcher_round"
 		android:name=".App" android:allowBackup="false">
-		<activity android:name="org.gioui.GioActivity"
+		<activity android:name="IPNActivity"
 			android:label="@string/app_name"
 			android:theme="@style/Theme.GioApp"
 			android:configChanges="orientation|screenSize|screenLayout|smallestScreenSize|keyboardHidden"
@@ -22,6 +22,28 @@
 			<intent-filter>
 				<action android:name="android.service.quicksettings.action.QS_TILE_PREFERENCES" />
 			</intent-filter>
+			<intent-filter>
+				<action android:name="android.intent.action.SEND" />
+				<category android:name="android.intent.category.DEFAULT"/>
+				<data android:mimeType="application/*" />
+				<data android:mimeType="audio/*" />
+				<data android:mimeType="image/*" />
+				<data android:mimeType="message/*" />
+				<data android:mimeType="multipart/*" />
+				<data android:mimeType="text/*" />
+				<data android:mimeType="video/*" />
+			</intent-filter>
+			<intent-filter>
+				<action android:name="android.intent.action.SEND_MULTIPLE" />
+				<category android:name="android.intent.category.DEFAULT" />
+				<data android:mimeType="application/*" />
+				<data android:mimeType="audio/*" />
+				<data android:mimeType="image/*" />
+				<data android:mimeType="message/*" />
+				<data android:mimeType="multipart/*" />
+				<data android:mimeType="text/*" />
+				<data android:mimeType="video/*" />
+			</intent-filter>
 		</activity>
 		<service android:name=".IPNService"
 			android:permission="android.permission.BIND_VPN_SERVICE">

android/src/main/java/com/tailscale/ipn/App.java

@@ -8,7 +8,11 @@ import android.app.Application;
 import android.app.Activity;
 import android.app.Fragment;
 import android.app.FragmentTransaction;
+import android.app.NotificationChannel;
+import android.app.PendingIntent;
 import android.content.BroadcastReceiver;
+import android.content.ContentResolver;
+import android.content.ContentValues;
 import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
@@ -16,21 +20,28 @@ import android.content.SharedPreferences;
 import android.content.pm.PackageManager;
 import android.content.pm.PackageInfo;
 import android.content.pm.Signature;
+import android.provider.MediaStore;
 import android.provider.Settings;
 import android.net.ConnectivityManager;
 import android.net.Uri;
 import android.net.VpnService;
 import android.view.View;
 import android.os.Build;
+import android.os.Environment;
 import android.os.Handler;
 import android.os.Looper;
 
+import android.webkit.MimeTypeMap;
+
 import java.io.IOException;
 import java.io.File;
 import java.io.FileOutputStream;
 
 import java.security.GeneralSecurityException;
 
+import androidx.core.app.NotificationCompat;
+import androidx.core.app.NotificationManagerCompat;
+
 import androidx.security.crypto.EncryptedSharedPreferences;
 import androidx.security.crypto.MasterKey;
 
@@ -41,6 +52,15 @@ import org.gioui.Gio;
 public class App extends Application {
 	private final static String PEER_TAG = "peer";
 
+	static final String STATUS_CHANNEL_ID = "tailscale-status";
+	static final int STATUS_NOTIFICATION_ID = 1;
+
+	static final String NOTIFY_CHANNEL_ID = "tailscale-notify";
+	static final int NOTIFY_NOTIFICATION_ID = 2;
+
+	private static final String FILE_CHANNEL_ID = "tailscale-files";
+	private static final int FILE_NOTIFICATION_ID = 3;
+
 	private final static Handler mainHandler = new Handler(Looper.getMainLooper());
 
 	@Override public void onCreate() {
@@ -48,6 +68,11 @@ public class App extends Application {
 		// Load and initialize the Go library.
 		Gio.init(this);
 		registerNetworkCallback();
+
+		createNotificationChannel(NOTIFY_CHANNEL_ID, "Notifications", NotificationManagerCompat.IMPORTANCE_DEFAULT);
+		createNotificationChannel(STATUS_CHANNEL_ID, "VPN Status", NotificationManagerCompat.IMPORTANCE_LOW);
+		createNotificationChannel(FILE_CHANNEL_ID, "File transfers", NotificationManagerCompat.IMPORTANCE_DEFAULT);
+
 	}
 
 	private void registerNetworkCallback() {
@@ -209,6 +234,53 @@ public class App extends Application {
 		return null;
 	}
 
+	String insertMedia(String name, String mimeType) throws IOException {
+		ContentResolver resolver = getContentResolver();
+		ContentValues contentValues = new ContentValues();
+		contentValues.put(MediaStore.MediaColumns.DISPLAY_NAME, name);
+		if (!"".equals(mimeType)) {
+			contentValues.put(MediaStore.MediaColumns.MIME_TYPE, mimeType);
+		}
+		Uri root = MediaStore.Files.getContentUri("external");
+		return resolver.insert(root, contentValues).toString();
+	}
+
+	int openUri(String uri, String mode) throws IOException {
+		ContentResolver resolver = getContentResolver();
+		return resolver.openFileDescriptor(Uri.parse(uri), mode).detachFd();
+	}
+
+	void deleteUri(String uri) {
+		ContentResolver resolver = getContentResolver();
+		resolver.delete(Uri.parse(uri), null, null);
+	}
+
+	public void notifyFile(String uri, String msg) {
+		Intent fileIntent = new Intent(Intent.ACTION_VIEW, Uri.parse(uri));
+		PendingIntent pending = PendingIntent.getActivity(this, 0, fileIntent, PendingIntent.FLAG_UPDATE_CURRENT);
+		NotificationCompat.Builder builder = new NotificationCompat.Builder(this, FILE_CHANNEL_ID)
+			.setSmallIcon(R.drawable.ic_notification)
+			.setContentTitle("File received")
+			.setContentText(msg)
+			.setContentIntent(pending)
+			.setAutoCancel(true)
+			.setOnlyAlertOnce(true)
+			.setPriority(NotificationCompat.PRIORITY_DEFAULT);
+
+		NotificationManagerCompat nm = NotificationManagerCompat.from(this);
+		nm.notify(FILE_NOTIFICATION_ID, builder.build());
+	}
+
+	private void createNotificationChannel(String id, String name, int importance) {
+		if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) {
+			return;
+		}
+		NotificationChannel channel = new NotificationChannel(id, name, importance);
+		NotificationManagerCompat nm = NotificationManagerCompat.from(this);
+		nm.createNotificationChannel(channel);
+	}
+
 	static native void onVPNPrepared();
 	private static native void onConnectivityChanged(boolean connected);
+	static native void onShareIntent(int nfiles, int[] types, String[] mimes, String[] items, String[] names, long[] sizes);
 }

android/src/main/java/com/tailscale/ipn/IPNActivity.java

@@ -0,0 +1,117 @@
+// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package com.tailscale.ipn;
+
+import android.app.Activity;
+import android.content.res.AssetFileDescriptor;
+import android.content.res.Configuration;
+import android.content.Intent;
+import android.database.Cursor;
+import android.os.Bundle;
+import android.provider.OpenableColumns;
+import android.net.Uri;
+
+import java.util.List;
+import java.util.ArrayList;
+
+import org.gioui.GioView;
+
+public final class IPNActivity extends Activity {
+	private GioView view;
+
+	@Override public void onCreate(Bundle state) {
+		super.onCreate(state);
+		view = new GioView(this);
+		setContentView(view);
+		handleIntent();
+	}
+
+	@Override public void onNewIntent(Intent i) {
+		setIntent(i);
+		handleIntent();
+	}
+
+	private void handleIntent() {
+		Intent it = getIntent();
+		String act = it.getAction();
+		String[] texts;
+		Uri[] uris;
+		if (Intent.ACTION_SEND.equals(act)) {
+			uris = new Uri[]{it.getParcelableExtra(Intent.EXTRA_STREAM)};
+			texts = new String[]{it.getStringExtra(Intent.EXTRA_TEXT)};
+		} else if (Intent.ACTION_SEND_MULTIPLE.equals(act)) {
+			List<Uri> extraUris = it.getParcelableArrayListExtra(Intent.EXTRA_STREAM);
+			uris = extraUris.toArray(new Uri[0]);
+			texts = new String[uris.length];
+		} else {
+			return;
+		}
+		String mime = it.getType();
+		int nitems = uris.length;
+		String[] items = new String[nitems];
+		String[] mimes = new String[nitems];
+		int[] types = new int[nitems];
+		String[] names = new String[nitems];
+		long[] sizes = new long[nitems];
+		int nfiles = 0;
+		for (int i = 0; i < uris.length; i++) {
+			String text = texts[i];
+			Uri uri = uris[i];
+			if (text != null) {
+				types[nfiles] = 1; // FileTypeText
+				names[nfiles] = "file.txt";
+				mimes[nfiles] = mime;
+				items[nfiles] = text;
+				// Determined by len(text) in Go to eliminate UTF-8 encoding differences.
+				sizes[nfiles] = 0;
+				nfiles++;
+			} else if (uri != null) {
+				Cursor c = getContentResolver().query(uri, null, null, null, null);
+				int nameCol = c.getColumnIndex(OpenableColumns.DISPLAY_NAME);
+				int sizeCol = c.getColumnIndex(OpenableColumns.SIZE);
+				c.moveToFirst();
+				String name = c.getString(nameCol);
+				long size = c.getLong(sizeCol);
+				types[nfiles] = 2; // FileTypeURI
+				mimes[nfiles] = mime;
+				items[nfiles] = uri.toString();
+				names[nfiles] = name;
+				sizes[nfiles] = size;
+				nfiles++;
+			}
+		}
+		App.onShareIntent(nfiles, types, mimes, items, names, sizes);
+	}
+
+	@Override public void onDestroy() {
+		view.destroy();
+		super.onDestroy();
+	}
+
+	@Override public void onStart() {
+		super.onStart();
+		view.start();
+	}
+
+	@Override public void onStop() {
+		view.stop();
+		super.onStop();
+	}
+
+	@Override public void onConfigurationChanged(Configuration c) {
+		super.onConfigurationChanged(c);
+		view.configurationChanged();
+	}
+
+	@Override public void onLowMemory() {
+		super.onLowMemory();
+		view.onLowMemory();
+	}
+
+	@Override public void onBackPressed() {
+		if (!view.backPressed())
+			super.onBackPressed();
+	}
+}

android/src/main/java/com/tailscale/ipn/IPNService.java

@@ -6,7 +6,6 @@ package com.tailscale.ipn;
 
 import android.os.Build;
 import android.app.PendingIntent;
-import android.app.NotificationChannel;
 import android.content.Intent;
 import android.content.pm.PackageManager;
 import android.net.VpnService;
@@ -21,14 +20,6 @@ public class IPNService extends VpnService {
 	public static final String ACTION_CONNECT = "com.tailscale.ipn.CONNECT";
 	public static final String ACTION_DISCONNECT = "com.tailscale.ipn.DISCONNECT";
 
-	private static final String STATUS_CHANNEL_ID = "tailscale-status";
-	private static final String STATUS_CHANNEL_NAME = "VPN Status";
-	private static final int STATUS_NOTIFICATION_ID = 1;
-
-	private static final String NOTIFY_CHANNEL_ID = "tailscale-notify";
-	private static final String NOTIFY_CHANNEL_NAME = "Notifications";
-	private static final int NOTIFY_NOTIFICATION_ID = 2;
-
 	@Override public int onStartCommand(Intent intent, int flags, int startId) {
 		if (intent != null && ACTION_DISCONNECT.equals(intent.getAction())) {
 			close();
@@ -70,9 +61,7 @@ public class IPNService extends VpnService {
 	}
 
 	public void notify(String title, String message) {
-		createNotificationChannel(NOTIFY_CHANNEL_ID, NOTIFY_CHANNEL_NAME, NotificationManagerCompat.IMPORTANCE_DEFAULT);
+		NotificationCompat.Builder builder = new NotificationCompat.Builder(this, App.NOTIFY_CHANNEL_ID)
-
-		NotificationCompat.Builder builder = new NotificationCompat.Builder(this, NOTIFY_CHANNEL_ID)
 			.setSmallIcon(R.drawable.ic_notification)
 			.setContentTitle(title)
 			.setContentText(message)
@@ -82,29 +71,18 @@ public class IPNService extends VpnService {
 			.setPriority(NotificationCompat.PRIORITY_DEFAULT);
 
 		NotificationManagerCompat nm = NotificationManagerCompat.from(this);
-		nm.notify(NOTIFY_NOTIFICATION_ID, builder.build());
+		nm.notify(App.NOTIFY_NOTIFICATION_ID, builder.build());
 	}
 
 	public void updateStatusNotification(String title, String message) {
-		createNotificationChannel(STATUS_CHANNEL_ID, STATUS_CHANNEL_NAME, NotificationManagerCompat.IMPORTANCE_LOW);
+		NotificationCompat.Builder builder = new NotificationCompat.Builder(this, App.STATUS_CHANNEL_ID)
-
-		NotificationCompat.Builder builder = new NotificationCompat.Builder(this, STATUS_CHANNEL_ID)
 			.setSmallIcon(R.drawable.ic_notification)
 			.setContentTitle(title)
 			.setContentText(message)
 			.setContentIntent(configIntent())
 			.setPriority(NotificationCompat.PRIORITY_LOW);
 
-		startForeground(STATUS_NOTIFICATION_ID, builder.build());
+		startForeground(App.STATUS_NOTIFICATION_ID, builder.build());
-	}
-
-	private void createNotificationChannel(String id, String name, int importance) {
-		if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) {
-			return;
-		}
-		NotificationChannel channel = new NotificationChannel(id, name, importance);
-		NotificationManagerCompat nm = NotificationManagerCompat.from(this);
-		nm.createNotificationChannel(channel);
 	}
 
 	private native void connect();

cmd/tailscale/callbacks.go

@@ -36,6 +36,9 @@ var (
 
 	// onGoogleToken receives google ID tokens.
 	onGoogleToken = make(chan string)
+
+	// onFileShare receives file sharing intents.
+	onFileShare = make(chan []File, 1)
 )
 
 const (
@@ -129,3 +132,45 @@ func Java_com_tailscale_ipn_Peer_onActivityResult0(env *C.JNIEnv, cls C.jclass,
 		}
 	}
 }
+
+//export Java_com_tailscale_ipn_App_onShareIntent
+func Java_com_tailscale_ipn_App_onShareIntent(env *C.JNIEnv, cls C.jclass, nfiles C.jint, jtypes C.jintArray, jmimes C.jobjectArray, jitems C.jobjectArray, jnames C.jobjectArray, jsizes C.jlongArray) {
+	const (
+		typeNone   = 0
+		typeInline = 1
+		typeURI    = 2
+	)
+	jenv := (*jni.Env)(unsafe.Pointer(env))
+	types := jni.GetIntArrayElements(jenv, jni.IntArray(jtypes))
+	mimes := jni.GetStringArrayElements(jenv, jni.ObjectArray(jmimes))
+	items := jni.GetStringArrayElements(jenv, jni.ObjectArray(jitems))
+	names := jni.GetStringArrayElements(jenv, jni.ObjectArray(jnames))
+	sizes := jni.GetLongArrayElements(jenv, jni.LongArray(jsizes))
+	var files []File
+	for i := 0; i < int(nfiles); i++ {
+		f := File{
+			Type:     FileType(types[i]),
+			MIMEType: mimes[i],
+			Name:     names[i],
+		}
+		if f.Name == "" {
+			f.Name = "file.bin"
+		}
+		switch f.Type {
+		case FileTypeText:
+			f.Text = items[i]
+			f.Size = int64(len(f.Text))
+		case FileTypeURI:
+			f.URI = items[i]
+			f.Size = sizes[i]
+		default:
+			panic("unknown file type")
+		}
+		files = append(files, f)
+	}
+	select {
+	case <-onFileShare:
+	default:
+	}
+	onFileShare <- files
+}

cmd/tailscale/main.go

@@ -5,9 +5,17 @@
 package main
 
 import (
+	"context"
 	"crypto/sha1"
+	"errors"
 	"fmt"
+	"io"
 	"log"
+	"mime"
+	"net/http"
+	"net/url"
+	"os"
+	"path/filepath"
 	"sort"
 	"strings"
 	"time"
@@ -20,9 +28,12 @@ import (
 	"inet.af/netaddr"
 
 	"github.com/tailscale/tailscale-android/jni"
+	"tailscale.com/client/tailscale/apitype"
 	"tailscale.com/ipn"
+	"tailscale.com/ipn/ipnlocal"
 	"tailscale.com/net/dns"
 	"tailscale.com/net/netns"
+	"tailscale.com/paths"
 	"tailscale.com/tailcfg"
 	"tailscale.com/types/netmap"
 	"tailscale.com/wgengine/router"
@@ -41,10 +52,10 @@ type App struct {
 	prefs chan *ipn.Prefs
 	// browseURLs receives URLs when the backend wants to browse.
 	browseURLs chan string
-
+	// targetsLoaded receives lists of file targets.
-	// backend is the channel for events from the frontend to the
+	targetsLoaded chan FileTargets
-	// backend.
+	// invalidates receives whenever the window should be refreshed.
-	backendEvents chan UIEvent
+	invalidates chan struct{}
 }
 
 var (
@@ -52,6 +63,30 @@ var (
 	googleClass jni.Class
 )
 
+type FileTargets struct {
+	Targets []*apitype.FileTarget
+	Err     error
+}
+
+type File struct {
+	Type     FileType
+	Name     string
+	Size     int64
+	MIMEType string
+	// URI of the file, valid if Type is FileTypeURI.
+	URI string
+	// Text is the content of the file, if Type is FileTypeText.
+	Text string
+}
+
+// FileSendInfo describes the state of an ongoing file send operation.
+type FileSendInfo struct {
+	State FileSendState
+	// Progress tracks the progress of the transfer from 0.0 to 1.0. Valid
+	// only when State is FileSendStarted.
+	Progress float64
+}
+
 type clientState struct {
 	browseURL string
 	backend   BackendState
@@ -61,6 +96,14 @@ type clientState struct {
 	Peers []UIPeer
 }
 
+type FileType uint8
+
+// FileType constants are known to IPNActivity.java.
+const (
+	FileTypeText FileType = 1
+	FileTypeURI  FileType = 2
+)
+
 type ExitStatus uint8
 
 const (
@@ -72,7 +115,17 @@ const (
 	ExitOnline
 )
 
-type ExitNode struct {
+type FileSendState uint8
+
+const (
+	FileSendNotStarted FileSendState = iota
+	FileSendConnecting
+	FileSendTransferring
+	FileSendComplete
+	FileSendFailed
+)
+
+type Peer struct {
 	Label  string
 	Online bool
 	ID     tailcfg.StableNodeID
@@ -84,11 +137,11 @@ type BackendState struct {
 	NetworkMap   *netmap.NetworkMap
 	LostInternet bool
 	// Exits are the peers that can act as exit node.
-	Exits []ExitNode
+	Exits []Peer
 	// ExitState describes the state of our exit node.
 	ExitStatus ExitStatus
 	// Exit is our current exit node, if any.
-	Exit ExitNode
+	Exit Peer
 }
 
 // UIEvent is an event flowing from the UI to the backend.
@@ -114,6 +167,12 @@ type OAuth2Event struct {
 	Token *tailcfg.Oauth2Token
 }
 
+type FileSendEvent struct {
+	Target  *apitype.FileTarget
+	Context context.Context
+	Updates func(FileSendInfo)
+}
+
 // UIEvent types.
 type (
 	ToggleEvent      struct{}
@@ -121,6 +180,7 @@ type (
 	WebAuthEvent     struct{}
 	GoogleAuthEvent  struct{}
 	LogoutEvent      struct{}
+	FileTargetsEvent struct{}
 )
 
 // serverOAuthID is the OAuth ID of the tailscale-android server, used
@@ -141,6 +201,8 @@ func main() {
 		netStates:     make(chan BackendState, 1),
 		browseURLs:    make(chan string, 1),
 		prefs:         make(chan *ipn.Prefs, 1),
+		targetsLoaded: make(chan FileTargets, 1),
+		invalidates:   make(chan struct{}, 1),
 	}
 	err := jni.Do(a.jvm, func(env *jni.Env) error {
 		loader := jni.ClassLoaderFor(env, a.appCtx)
@@ -174,6 +236,7 @@ func (a *App) runBackend() error {
 	if err != nil {
 		fatalErr(err)
 	}
+	paths.AppSharedDir.Store(appDir)
 	type configPair struct {
 		rcfg *router.Config
 		dcfg *dns.OSConfig
@@ -223,12 +286,33 @@ func (a *App) runBackend() error {
 		service   jni.Object // of IPNService
 		signingIn bool
 	)
+	var (
+		waitingFilesDone = make(chan struct{})
+		waitingFiles     bool
+		processingFiles  bool
+	)
+	processFiles := func() {
+		if !waitingFiles || processingFiles {
+			return
+		}
+		processingFiles = true
+		waitingFiles = false
+		go func() {
+			if err := a.processWaitingFiles(b.backend); err != nil {
+				log.Printf("processWaitingFiles: %v", err)
+			}
+			waitingFilesDone <- struct{}{}
+		}()
+	}
 	for {
 		select {
 		case err := <-startErr:
 			if err != nil {
 				return err
 			}
+		case <-waitingFilesDone:
+			processingFiles = false
+			processFiles()
 		case s := <-configs:
 			cfg = s
 			if b == nil || service == 0 || cfg.rcfg == nil {
@@ -290,6 +374,18 @@ func (a *App) runBackend() error {
 			if service != 0 && exitWasOnline && state.ExitStatus == ExitOffline {
 				a.pushNotify(service, "Connection Lost", "Your exit node is offline. Disable your exit node or contact your network admin for help.")
 			}
+			targets, err := b.backend.FileTargets()
+			if err != nil {
+				// Construct a user-visible error message.
+				if b.backend.State() != ipn.Running {
+					err = fmt.Errorf("Not connected to tailscale")
+				} else {
+					err = fmt.Errorf("Failed to load device list")
+				}
+			}
+			a.targetsLoaded <- FileTargets{targets, err}
+			waitingFiles = n.FilesWaiting != nil
+			processFiles()
 		case <-alarmChan:
 			if m := state.NetworkMap; m != nil && service != 0 {
 				alarm(a.notifyExpiry(service, m.Expiry))
@@ -385,6 +481,90 @@ func (a *App) runBackend() error {
 	}
 }
 
+func (a *App) processWaitingFiles(b *ipnlocal.LocalBackend) error {
+	files, err := b.WaitingFiles()
+	if err != nil {
+		return err
+	}
+	var aerr error
+	for _, f := range files {
+		if err := a.downloadFile(b, f); err != nil && aerr == nil {
+			aerr = err
+		}
+	}
+	return aerr
+}
+
+func (a *App) downloadFile(b *ipnlocal.LocalBackend, f apitype.WaitingFile) (cerr error) {
+	in, _, err := b.OpenFile(f.Name)
+	if err != nil {
+		return err
+	}
+	defer in.Close()
+	ext := filepath.Ext(f.Name)
+	mimeType := mime.TypeByExtension(ext)
+	var mediaURI string
+	err = jni.Do(a.jvm, func(env *jni.Env) error {
+		cls := jni.GetObjectClass(env, a.appCtx)
+		insertMedia := jni.GetMethodID(env, cls, "insertMedia", "(Ljava/lang/String;Ljava/lang/String;)Ljava/lang/String;")
+		jname := jni.JavaString(env, f.Name)
+		jmime := jni.JavaString(env, mimeType)
+		uri, err := jni.CallObjectMethod(env, a.appCtx, insertMedia, jni.Value(jname), jni.Value(jmime))
+		if err != nil {
+			return err
+		}
+		mediaURI = jni.GoString(env, jni.String(uri))
+		return nil
+	})
+	if err != nil {
+		return fmt.Errorf("insertMedia: %w", err)
+	}
+	deleteURI := func(uri string) error {
+		return jni.Do(a.jvm, func(env *jni.Env) error {
+			cls := jni.GetObjectClass(env, a.appCtx)
+			m := jni.GetMethodID(env, cls, "deleteUri", "(Ljava/lang/String;)V")
+			juri := jni.JavaString(env, uri)
+			return jni.CallVoidMethod(env, a.appCtx, m, jni.Value(juri))
+		})
+	}
+	out, err := a.openURI(mediaURI, "w")
+	if err != nil {
+		deleteURI(mediaURI)
+		return fmt.Errorf("openUri: %w", err)
+	}
+	if _, err := io.Copy(out, in); err != nil {
+		deleteURI(mediaURI)
+		return fmt.Errorf("copy: %w", err)
+	}
+	if err := out.Close(); err != nil {
+		deleteURI(mediaURI)
+		return fmt.Errorf("close: %w", err)
+	}
+	if err := a.notifyFile(mediaURI, f.Name); err != nil {
+		fatalErr(err)
+	}
+	return b.DeleteFile(f.Name)
+}
+
+// openURI calls a.appCtx.getContentResolver().openFileDescriptor on uri and
+// mode and returns the detached file descriptor.
+func (a *App) openURI(uri, mode string) (*os.File, error) {
+	var f *os.File
+	err := jni.Do(a.jvm, func(env *jni.Env) error {
+		cls := jni.GetObjectClass(env, a.appCtx)
+		openURI := jni.GetMethodID(env, cls, "openUri", "(Ljava/lang/String;Ljava/lang/String;)I")
+		juri := jni.JavaString(env, uri)
+		jmode := jni.JavaString(env, mode)
+		fd, err := jni.CallIntMethod(env, a.appCtx, openURI, jni.Value(juri), jni.Value(jmode))
+		if err != nil {
+			return err
+		}
+		f = os.NewFile(uintptr(fd), "media-store")
+		return nil
+	})
+	return f, err
+}
+
 func (a *App) isChromeOS() bool {
 	var chromeOS bool
 	err := jni.Do(a.jvm, func(env *jni.Env) error {
@@ -425,7 +605,7 @@ func (s *BackendState) updateExitNodes() {
 		}
 		myExit := p.StableID == exitID
 		hasMyExit = hasMyExit || myExit
-		exit := ExitNode{
+		exit := Peer{
 			Label:  p.DisplayName(true),
 			Online: canRoute,
 			ID:     p.StableID,
@@ -445,8 +625,8 @@ func (s *BackendState) updateExitNodes() {
 	})
 	if !hasMyExit {
 		// Insert node missing from netmap.
-		s.Exit = ExitNode{Label: "Unknown device", ID: exitID}
+		s.Exit = Peer{Label: "Unknown device", ID: exitID}
-		s.Exits = append([]ExitNode{s.Exit}, s.Exits...)
+		s.Exits = append([]Peer{s.Exit}, s.Exits...)
 	}
 }
 
@@ -561,6 +741,16 @@ func (a *App) notifyExpiry(service jni.Object, expiry time.Time) *time.Timer {
 	return t
 }
 
+func (a *App) notifyFile(uri, msg string) error {
+	return jni.Do(a.jvm, func(env *jni.Env) error {
+		cls := jni.GetObjectClass(env, a.appCtx)
+		notify := jni.GetMethodID(env, cls, "notifyFile", "(Ljava/lang/String;Ljava/lang/String;)V")
+		juri := jni.JavaString(env, uri)
+		jmsg := jni.JavaString(env, msg)
+		return jni.CallVoidMethod(env, a.appCtx, notify, jni.Value(juri), jni.Value(jmsg))
+	})
+}
+
 func (a *App) pushNotify(service jni.Object, title, msg string) error {
 	return jni.Do(a.jvm, func(env *jni.Env) error {
 		cls := jni.GetObjectClass(env, service)
@@ -615,6 +805,8 @@ func (a *App) runUI() error {
 		// activity is the most recent Android Activity reference as reported
 		// by Gio ViewEvents.
 		activity jni.Object
+		// files is list of files from the most recent file sharing intent.
+		files []File
 	)
 	deleteActivityRef := func() {
 		if activity == 0 {
@@ -677,6 +869,15 @@ func (a *App) runUI() error {
 		case <-onVPNRevoked:
 			ui.ShowMessage("VPN access denied or another VPN service is always-on")
 			w.Invalidate()
+		case files = <-onFileShare:
+			ui.ShowShareDialog()
+			w.Invalidate()
+			backendEvents <- FileTargetsEvent{}
+		case t := <-a.targetsLoaded:
+			ui.FillShareDialog(t.Targets, t.Err)
+			w.Invalidate()
+		case <-a.invalidates:
+			w.Invalidate()
 		case e := <-w.Events():
 			switch e := e.(type) {
 			case app.ViewEvent:
@@ -699,6 +900,7 @@ func (a *App) runUI() error {
 				if e.Type == system.CommandBack {
 					if ui.onBack() {
 						e.Cancel = true
+						w.Invalidate()
 					}
 				}
 			case system.FrameEvent:
@@ -707,7 +909,7 @@ func (a *App) runUI() error {
 				gtx := layout.NewContext(&ops, e)
 				events := ui.layout(gtx, ins, state)
 				e.Frame(gtx.Ops)
-				a.processUIEvents(w, events, activity, state)
+				a.processUIEvents(w, events, activity, state, files)
 			}
 		}
 	}
@@ -829,7 +1031,7 @@ func requestBackend(e UIEvent) {
 	}()
 }
 
-func (a *App) processUIEvents(w *app.Window, events []UIEvent, act jni.Object, state *clientState) {
+func (a *App) processUIEvents(w *app.Window, events []UIEvent, act jni.Object, state *clientState, files []File) {
 	for _, e := range events {
 		switch e := e.(type) {
 		case ReauthEvent:
@@ -858,8 +1060,109 @@ func (a *App) processUIEvents(w *app.Window, events []UIEvent, act jni.Object, s
 		case SearchEvent:
 			state.query = strings.ToLower(e.Query)
 			a.updateState(act, state)
+		case FileSendEvent:
+			a.sendFiles(e, files)
+		}
+	}
+}
+
+func (a *App) sendFiles(e FileSendEvent, files []File) {
+	go func() {
+		var totalSize int64
+		for _, f := range files {
+			totalSize += f.Size
+		}
+		if totalSize == 0 {
+			totalSize = 1
+		}
+		var totalSent int64
+		progress := func(n int64) {
+			totalSent += n
+			e.Updates(FileSendInfo{
+				State:    FileSendTransferring,
+				Progress: float64(totalSent) / float64(totalSize),
+			})
+			a.invalidate()
 		}
+		defer a.invalidate()
+		for _, f := range files {
+			if err := a.sendFile(e.Context, e.Target, f, progress); err != nil {
+				if errors.Is(err, context.Canceled) {
+					return
 				}
+				e.Updates(FileSendInfo{
+					State: FileSendFailed,
+				})
+				return
+			}
+		}
+		e.Updates(FileSendInfo{
+			State: FileSendComplete,
+		})
+	}()
+}
+
+func (a *App) invalidate() {
+	select {
+	case a.invalidates <- struct{}{}:
+	default:
+	}
+}
+
+func (a *App) sendFile(ctx context.Context, target *apitype.FileTarget, f File, progress func(n int64)) error {
+	var body io.Reader
+	switch f.Type {
+	case FileTypeText:
+		body = strings.NewReader(f.Text)
+	case FileTypeURI:
+		f, err := a.openURI(f.URI, "r")
+		if err != nil {
+			return err
+		}
+		defer f.Close()
+		body = f
+	default:
+		panic("unknown file type")
+	}
+	body = &progressReader{r: body, size: f.Size, progress: progress}
+	dstURL := target.PeerAPIURL + "/v0/put/" + url.PathEscape(f.Name)
+	req, err := http.NewRequestWithContext(ctx, "PUT", dstURL, body)
+	if err != nil {
+		return err
+	}
+	req.ContentLength = f.Size
+	res, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return err
+	}
+	defer res.Body.Close()
+	if res.StatusCode != 200 {
+		return fmt.Errorf("PUT failed: %s", res.Status)
+	}
+	return nil
+}
+
+// progressReader wraps an io.Reader to call a progress function
+// on every non-zero Read.
+type progressReader struct {
+	r        io.Reader
+	bytes    int64
+	size     int64
+	eof      bool
+	progress func(n int64)
+}
+
+func (r *progressReader) Read(p []byte) (int, error) {
+	n, err := r.r.Read(p)
+	// The request body may be read after http.Client.Do returns, see
+	// https://github.com/golang/go/issues/30597. Don't update progress if the
+	// file has been read.
+	r.eof = r.eof || errors.Is(err, io.EOF)
+	if !r.eof && r.bytes < r.size {
+		r.progress(int64(n))
+		r.bytes += int64(n)
+	}
+	return n, err
 }
 
 func (a *App) signOut() {

cmd/tailscale/ui.go

@@ -6,6 +6,7 @@ package main
 
 import (
 	"bytes"
+	"context"
 	"fmt"
 	"image"
 	"image/color"
@@ -25,6 +26,7 @@ import (
 	"gioui.org/widget/material"
 	"golang.org/x/exp/shiny/materialdesign/icons"
 	"inet.af/netaddr"
+	"tailscale.com/client/tailscale/apitype"
 	"tailscale.com/ipn"
 	"tailscale.com/tailcfg"
 
@@ -92,15 +94,35 @@ type UI struct {
 		t0 time.Time
 	}
 
+	shareDialog struct {
+		show    bool
+		dismiss Dismiss
+		list    layout.List
+		// peers are the nodes ready to receive files.
+		targets []shareTarget
+		loaded  bool
+		error   error
+	}
+
 	icons struct {
 		search     *widget.Icon
 		more       *widget.Icon
 		exitStatus *widget.Icon
+		done       *widget.Icon
+		error      *widget.Icon
 		logo       paint.ImageOp
 		google     paint.ImageOp
 	}
 }
 
+type shareTarget struct {
+	btn     widget.Clickable
+	target  *apitype.FileTarget
+	info    FileSendInfo
+	cancel  func()
+	updates <-chan FileSendInfo
+}
+
 type signinType uint8
 
 // An UIPeer is either a peer or a section header
@@ -161,6 +183,14 @@ func newUI(store *stateStore) (*UI, error) {
 	if err != nil {
 		return nil, err
 	}
+	doneIcon, err := widget.NewIcon(icons.ActionCheckCircle)
+	if err != nil {
+		return nil, err
+	}
+	errorIcon, err := widget.NewIcon(icons.AlertErrorOutline)
+	if err != nil {
+		return nil, err
+	}
 	logo, _, err := image.Decode(bytes.NewReader(tailscaleLogo))
 	if err != nil {
 		return nil, err
@@ -189,15 +219,20 @@ func newUI(store *stateStore) (*UI, error) {
 	ui.icons.search = searchIcon
 	ui.icons.more = moreIcon
 	ui.icons.exitStatus = exitStatus
+	ui.icons.done = doneIcon
+	ui.icons.error = errorIcon
 	ui.icons.logo = paint.NewImageOp(logo)
 	ui.icons.google = paint.NewImageOp(google)
 	ui.icons.more.Color = rgb(white)
 	ui.icons.search.Color = mulAlpha(ui.theme.Palette.Fg, 0xbb)
 	ui.icons.exitStatus.Color = rgb(white)
+	ui.icons.done.Color = ui.theme.Palette.ContrastBg
+	ui.icons.error.Color = rgb(0xcc6539)
 	ui.root.Axis = layout.Vertical
 	ui.intro.list.Axis = layout.Vertical
 	ui.search.SingleLine = true
 	ui.exitDialog.list.Axis = layout.Vertical
+	ui.shareDialog.list.Axis = layout.Vertical
 	return ui, nil
 }
 
@@ -207,11 +242,18 @@ func mulAlpha(c color.NRGBA, alpha uint8) color.NRGBA {
 }
 
 func (ui *UI) onBack() bool {
-	if !ui.menu.show {
+	switch {
-		return false
+	case ui.menu.show:
-	}
 		ui.menu.show = false
 		return true
+	case ui.shareDialog.show:
+		ui.shareDialog.show = false
+		return true
+	case ui.exitDialog.show:
+		ui.exitDialog.show = false
+		return true
+	}
+	return false
 }
 
 func (ui *UI) layout(gtx layout.Context, sysIns system.Insets, state *clientState) []UIEvent {
@@ -284,6 +326,42 @@ func (ui *UI) layout(gtx layout.Context, sysIns system.Insets, state *clientStat
 		events = append(events, LogoutEvent{})
 	}
 
+	for i := range ui.shareDialog.targets {
+		t := &ui.shareDialog.targets[i]
+		select {
+		case t.info = <-t.updates:
+		default:
+		}
+		if !t.btn.Clicked() {
+			continue
+		}
+		switch t.info.State {
+		case FileSendTransferring, FileSendConnecting:
+			t.cancel()
+			t.info.State = FileSendNotStarted
+			t.updates = nil
+			continue
+		}
+		t.info = FileSendInfo{
+			State: FileSendConnecting,
+		}
+		ctx, cancel := context.WithCancel(context.Background())
+		t.cancel = cancel
+		updates := make(chan FileSendInfo, 1)
+		t.updates = updates
+		events = append(events, FileSendEvent{
+			Target:  t.target,
+			Context: ctx,
+			Updates: func(info FileSendInfo) {
+				select {
+				case <-updates:
+				default:
+				}
+				updates <- info
+			},
+		})
+	}
+
 	for len(ui.peers) < len(state.Peers) {
 		ui.peers = append(ui.peers, widget.Clickable{})
 	}
@@ -360,6 +438,8 @@ func (ui *UI) layout(gtx layout.Context, sysIns system.Insets, state *clientStat
 
 	ui.layoutExitNodeDialog(gtx, sysIns, state.backend.Exits)
 
+	ui.layoutShareDialog(gtx, sysIns)
+
 	// Popup messages.
 	ui.layoutMessage(gtx, sysIns)
 
@@ -380,6 +460,31 @@ func (ui *UI) layout(gtx layout.Context, sysIns system.Insets, state *clientStat
 	return events
 }
 
+func (ui *UI) FillShareDialog(targets []*apitype.FileTarget, err error) {
+	ui.shareDialog.error = err
+	ui.shareDialog.loaded = true
+	targetSet := make(map[tailcfg.NodeID]int)
+	if ui.shareDialog.show {
+		// Update rather than replace list.
+		for i, t := range ui.shareDialog.targets {
+			targetSet[t.target.Node.ID] = i
+		}
+	} else {
+		ui.shareDialog.targets = nil
+	}
+	for _, t := range targets {
+		if i, ok := targetSet[t.Node.ID]; ok {
+			ui.shareDialog.targets[i].target = t
+		} else {
+			ui.shareDialog.targets = append(ui.shareDialog.targets, shareTarget{target: t})
+		}
+	}
+}
+
+func (ui *UI) ShowShareDialog() {
+	ui.shareDialog.show = true
+}
+
 func (ui *UI) ShowMessage(msg string) {
 	ui.message.text = msg
 	ui.message.t0 = time.Now()
@@ -623,9 +728,118 @@ func (ui *UI) menuClicked(btn *widget.Clickable) bool {
 	return cl
 }
 
-// layoutExitNodeDialog lays out the exit node selection dialog. If the user changed the node,
+// layoutShareDialog lays out the file sharing dialog shown on file send intents (ACTION_SEND, ACTION_SEND_MULTIPLE).
-// true is returned along with the node.
+func (ui *UI) layoutShareDialog(gtx layout.Context, sysIns system.Insets) {
-func (ui *UI) layoutExitNodeDialog(gtx layout.Context, sysIns system.Insets, exits []ExitNode) {
+	d := &ui.shareDialog
+	if d.dismiss.Dismissed(gtx) {
+		ui.shareDialog.show = false
+	}
+	if !d.show {
+		return
+	}
+	d.dismiss.Add(gtx, argb(0x66000000))
+	layout.Inset{
+		Top:    unit.Add(gtx.Metric, sysIns.Top, unit.Dp(16)),
+		Right:  unit.Add(gtx.Metric, sysIns.Right, unit.Dp(16)),
+		Bottom: unit.Add(gtx.Metric, sysIns.Bottom, unit.Dp(16)),
+		Left:   unit.Add(gtx.Metric, sysIns.Left, unit.Dp(16)),
+	}.Layout(gtx, func(gtx C) D {
+		return layout.Center.Layout(gtx, func(gtx C) D {
+			gtx.Constraints.Min.X = gtx.Px(unit.Dp(250))
+			gtx.Constraints.Max.X = gtx.Constraints.Min.X
+			return layoutDialog(gtx, func(gtx C) D {
+				return layout.Flex{Axis: layout.Vertical}.Layout(gtx,
+					layout.Rigid(func(gtx C) D {
+						// Header.
+						d := layout.Inset{
+							Top:    unit.Dp(16),
+							Right:  unit.Dp(20),
+							Left:   unit.Dp(20),
+							Bottom: unit.Dp(16),
+						}.Layout(gtx, func(gtx C) D {
+							l := material.Body1(ui.theme, "Share via Tailscale")
+							l.Font.Weight = text.Bold
+							return l.Layout(gtx)
+						})
+						// Swallow clicks to title.
+						var c widget.Clickable
+						gtx.Constraints.Min = d.Size
+						c.Layout(gtx)
+						return d
+					}),
+					layout.Rigid(func(gtx C) D {
+						if d.loaded {
+							return D{}
+						}
+						return layout.UniformInset(unit.Dp(50)).Layout(gtx, func(gtx C) D {
+							return layout.Center.Layout(gtx, func(gtx C) D {
+								sz := gtx.Px(unit.Dp(32))
+								gtx.Constraints.Min = image.Pt(sz, sz)
+								gtx.Constraints.Max = gtx.Constraints.Min
+								return material.Loader(ui.theme).Layout(gtx)
+							})
+						})
+					}),
+					layout.Rigid(func(gtx C) D {
+						if d.error == nil {
+							return D{}
+						}
+						sz := gtx.Px(unit.Dp(50))
+						gtx.Constraints.Min.Y = sz
+						return layout.UniformInset(unit.Dp(20)).Layout(gtx, func(gtx C) D {
+							return layout.W.Layout(gtx, func(gtx C) D {
+								return material.Body2(ui.theme, d.error.Error()).Layout(gtx)
+							})
+						})
+					}),
+					layout.Flexed(1, func(gtx C) D {
+						gtx.Constraints.Min.Y = 0
+						return d.list.Layout(gtx, len(d.targets), func(gtx C, idx int) D {
+							node := &d.targets[idx]
+							target := node.target.Node
+							lbl := target.ComputedName
+							offline := target.Online != nil && !*target.Online
+							if offline {
+								lbl = lbl + " (offline)"
+							}
+							w := material.Body2(ui.theme, lbl)
+							if offline {
+								w.Color = rgb(0xbbbbbb)
+								gtx.Queue = nil
+							}
+							return material.Clickable(gtx, &node.btn, func(gtx C) D {
+								return layout.UniformInset(unit.Dp(16)).Layout(gtx, func(gtx C) D {
+									return layout.Flex{Alignment: layout.Middle}.Layout(gtx,
+										layout.Flexed(1, w.Layout),
+										layout.Rigid(func(gtx C) D {
+											sz := gtx.Px(unit.Dp(16))
+											gtx.Constraints.Min = image.Pt(sz, sz)
+											switch node.info.State {
+											case FileSendConnecting:
+												return material.Loader(ui.theme).Layout(gtx)
+											case FileSendTransferring:
+												return material.ProgressCircle(ui.theme, float32(node.info.Progress)).Layout(gtx)
+											case FileSendFailed:
+												return ui.icons.error.Layout(gtx, unit.Dp(16))
+											case FileSendComplete:
+												return ui.icons.done.Layout(gtx, unit.Dp(16))
+											default:
+												return D{}
+											}
+										}),
+									)
+								})
+							})
+						})
+					}),
+				)
+			})
+		})
+	})
+}
+
+// layoutExitNodeDialog lays out the exit node selection dialog.
+func (ui *UI) layoutExitNodeDialog(gtx layout.Context, sysIns system.Insets, exits []Peer) {
 	d := &ui.exitDialog
 	if d.dismiss.Dismissed(gtx) {
 		d.show = false
@@ -663,10 +877,7 @@ func (ui *UI) layoutExitNodeDialog(gtx layout.Context, sysIns system.Insets, exi
 						// Add "none" exit node.
 						n := len(exits) + 1
 						return d.list.Layout(gtx, n, func(gtx C, idx int) D {
-							switch idx {
+							node := Peer{Label: "None", Online: true}
-							case n - 1:
-							}
-							node := ExitNode{Label: "None", Online: true}
 							if idx >= 1 {
 								node = exits[idx-1]
 							}

go.mod

@@ -4,7 +4,7 @@ go 1.16
 
 require (
 	eliasnaur.com/font v0.0.0-20200617114307-e02d32decb4b
-	gioui.org v0.0.0-20210623091900-5b8da35a798b
+	gioui.org v0.0.0-20210626160534-a87206c3647c
 	gioui.org/cmd v0.0.0-20210623091900-5b8da35a798b
 	golang.org/x/exp v0.0.0-20191227195350-da58074b4299
 	golang.org/x/sys v0.0.0-20210616094352-59db8d763f22

go.sum

@@ -15,8 +15,8 @@ dmitri.shuralyov.com/gpu/mtl v0.0.0-20190408044501-666a987793e9/go.mod h1:H6x//7
 eliasnaur.com/font v0.0.0-20200617114307-e02d32decb4b h1:J9r7EuPdhvBTafg34EqrObAm/bDEaDh7LvhKJPGficE=
 eliasnaur.com/font v0.0.0-20200617114307-e02d32decb4b/go.mod h1:CYwJpIhpzVfoHpFXGlXjSx9mXMWtHt4XXmZb6RjumRc=
 gioui.org v0.0.0-20210518185901-8611894b4bb3/go.mod h1:RSH6KIUZ0p2xy5zHDxgAM4zumjgTw83q2ge/PI+yyw8=
-gioui.org v0.0.0-20210623091900-5b8da35a798b h1:N5MMMh46Yg3o8UDFpfEzIIXi4K9x02QoHl89kjmqTOc=
+gioui.org v0.0.0-20210626160534-a87206c3647c h1:PUxsHY4Ig4hn1gXO1iuJzplNdjSEzQbMOagao20UHOU=
-gioui.org v0.0.0-20210623091900-5b8da35a798b/go.mod h1:RSH6KIUZ0p2xy5zHDxgAM4zumjgTw83q2ge/PI+yyw8=
+gioui.org v0.0.0-20210626160534-a87206c3647c/go.mod h1:RSH6KIUZ0p2xy5zHDxgAM4zumjgTw83q2ge/PI+yyw8=
 gioui.org/cmd v0.0.0-20210623091900-5b8da35a798b h1:qPEu8AvPmYvUyZmQcOzAj+vc+BmdVtWrhCeHIm+pGJU=
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