Merge branch '1507-extract-tor-binaries-to-lib-dir' into 'master'

Raise targetSdkVersion to 29, package Tor binaries as libraries

Closes #1507 and #1185

See merge request briar/briar!1279

bramble-android/src/main/java/org/briarproject/bramble/plugin/tor/AndroidTorPlugin.java

@@ -16,19 +16,42 @@ import org.briarproject.bramble.api.system.AndroidWakeLockManager;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.system.LocationUtils;
 import org.briarproject.bramble.api.system.ResourceProvider;
+import org.briarproject.bramble.util.AndroidUtils;
 
 import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
 import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipInputStream;
 
 import javax.net.SocketFactory;
 
+import static android.os.Build.VERSION.SDK_INT;
+import static java.util.Arrays.asList;
+import static java.util.logging.Level.INFO;
+import static java.util.logging.Logger.getLogger;
+
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 class AndroidTorPlugin extends TorPlugin {
 
+	private static final List<String> LIBRARY_ARCHITECTURES =
+			asList("armeabi-v7a", "arm64-v8a", "x86", "x86_64");
+
+	private static final String TOR_LIB_NAME = "libtor.so";
+	private static final String OBFS4_LIB_NAME = "libobfs4proxy.so";
+
+	private static final Logger LOG =
+			getLogger(AndroidTorPlugin.class.getName());
+
 	private final Application app;
 	private final AndroidWakeLock wakeLock;
+	private final File torLib, obfs4Lib;
 
 	AndroidTorPlugin(Executor ioExecutor,
 			Executor wakefulIoExecutor,
@@ -55,6 +78,9 @@ class AndroidTorPlugin extends TorPlugin {
 				maxIdleTime, torDirectory);
 		this.app = app;
 		wakeLock = wakeLockManager.createWakeLock("TorPlugin");
+		String nativeLibDir = app.getApplicationInfo().nativeLibraryDir;
+		torLib = new File(nativeLibDir, TOR_LIB_NAME);
+		obfs4Lib = new File(nativeLibDir, OBFS4_LIB_NAME);
 	}
 
 	@Override
@@ -85,4 +111,112 @@ class AndroidTorPlugin extends TorPlugin {
 		super.stop();
 		wakeLock.release();
 	}
+
+	@Override
+	protected File getTorExecutableFile() {
+		return torLib.exists() ? torLib : super.getTorExecutableFile();
+	}
+
+	@Override
+	protected File getObfs4ExecutableFile() {
+		return obfs4Lib.exists() ? obfs4Lib : super.getObfs4ExecutableFile();
+	}
+
+	@Override
+	protected void installTorExecutable() throws IOException {
+		File extracted = super.getTorExecutableFile();
+		if (torLib.exists()) {
+			// If an older version left behind a Tor binary, delete it
+			if (extracted.exists()) {
+				if (extracted.delete()) LOG.info("Deleted Tor binary");
+				else LOG.info("Failed to delete Tor binary");
+			}
+		} else if (SDK_INT < 29) {
+			// The binary wasn't extracted at install time. Try to extract it
+			extractLibraryFromApk(TOR_LIB_NAME, extracted);
+		} else {
+			// No point extracting the binary, we won't be allowed to execute it
+			throw new FileNotFoundException(torLib.getAbsolutePath());
+		}
+	}
+
+	@Override
+	protected void installObfs4Executable() throws IOException {
+		File extracted = super.getObfs4ExecutableFile();
+		if (obfs4Lib.exists()) {
+			// If an older version left behind an obfs4 binary, delete it
+			if (extracted.exists()) {
+				if (extracted.delete()) LOG.info("Deleted obfs4 binary");
+				else LOG.info("Failed to delete obfs4 binary");
+			}
+		} else if (SDK_INT < 29) {
+			// The binary wasn't extracted at install time. Try to extract it
+			extractLibraryFromApk(OBFS4_LIB_NAME, extracted);
+		} else {
+			// No point extracting the binary, we won't be allowed to execute it
+			throw new FileNotFoundException(obfs4Lib.getAbsolutePath());
+		}
+	}
+
+	private void extractLibraryFromApk(String libName, File dest)
+			throws IOException {
+		File sourceDir = new File(app.getApplicationInfo().sourceDir);
+		if (sourceDir.isFile()) {
+			// Look for other APK files in the same directory, if we're allowed
+			File parent = sourceDir.getParentFile();
+			if (parent != null) sourceDir = parent;
+		}
+		List<String> libPaths = getSupportedLibraryPaths(libName);
+		for (File apk : findApkFiles(sourceDir)) {
+			ZipInputStream zin = new ZipInputStream(new FileInputStream(apk));
+			for (ZipEntry e = zin.getNextEntry(); e != null;
+					e = zin.getNextEntry()) {
+				if (libPaths.contains(e.getName())) {
+					if (LOG.isLoggable(INFO)) {
+						LOG.info("Extracting " + e.getName()
+								+ " from " + apk.getAbsolutePath());
+					}
+					extract(zin, dest); // Zip input stream will be closed
+					return;
+				}
+			}
+			zin.close();
+		}
+		throw new FileNotFoundException(libName);
+	}
+
+	/**
+	 * Returns all files with the extension .apk or .APK under the given root.
+	 */
+	private List<File> findApkFiles(File root) {
+		List<File> files = new ArrayList<>();
+		findApkFiles(root, files);
+		return files;
+	}
+
+	private void findApkFiles(File f, List<File> files) {
+		if (f.isFile() && f.getName().toLowerCase().endsWith(".apk")) {
+			files.add(f);
+		} else if (f.isDirectory()) {
+			File[] children = f.listFiles();
+			if (children != null) {
+				for (File child : children) findApkFiles(child, files);
+			}
+		}
+	}
+
+	/**
+	 * Returns the paths at which libraries with the given name would be found
+	 * inside an APK file, for all architectures supported by the device, in
+	 * order of preference.
+	 */
+	private List<String> getSupportedLibraryPaths(String libName) {
+		List<String> architectures = new ArrayList<>();
+		for (String abi : AndroidUtils.getSupportedArchitectures()) {
+			if (LIBRARY_ARCHITECTURES.contains(abi)) {
+				architectures.add("lib/" + abi + "/" + libName);
+			}
+		}
+		return architectures;
+	}
 }