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package se.leap.bitmaskclient.tor;
/**
* Copyright (c) 2021 LEAP Encryption Access Project and contributors
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import static se.leap.bitmaskclient.tor.TorStatusObservable.SnowflakeStatus.RETRY_AMP_CACHE_RENDEZVOUS;
import static se.leap.bitmaskclient.tor.TorStatusObservable.SnowflakeStatus.RETRY_HTTP_RENDEZVOUS;
import android.content.Context;
import android.os.FileObserver;
import android.os.Handler;
import android.os.HandlerThread;
import android.util.Log;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import org.torproject.jni.ClientTransportPluginInterface;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.lang.ref.WeakReference;
import java.util.Collection;
import java.util.HashMap;
import java.util.Random;
import java.util.Scanner;
import java.util.Vector;
import java.util.concurrent.TimeoutException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import IPtProxy.IPtProxy;
public class ClientTransportPlugin implements ClientTransportPluginInterface, PropertyChangeListener {
public static String TAG = ClientTransportPlugin.class.getSimpleName();
private HashMap<String, String> mFronts;
private final WeakReference<Context> contextRef;
private long snowflakePort = -1;
private FileObserver logFileObserver;
private static final Pattern SNOWFLAKE_LOG_TIMESTAMP_PATTERN = Pattern.compile("((19|2[0-9])[0-9]{2}\\/\\d{1,2}\\/\\d{1,2} \\d{1,2}:\\d{1,2}:\\d{1,2}) ([\\S|\\s]+)");
private TorStatusObservable.SnowflakeStatus snowflakeStatus;
private String logfilePath;
Handler handler;
HandlerThread handlerThread;
public ClientTransportPlugin(Context context) {
this.contextRef = new WeakReference<>(context);
handlerThread = new HandlerThread("clientTransportPlugin", Thread.MIN_PRIORITY);
loadCdnFronts(context);
}
@Override
public void start() {
Context context = contextRef.get();
if (context == null) {
return;
}
handlerThread.start();
handler = new Handler(handlerThread.getLooper());
TorStatusObservable.getInstance().addObserver(this);
File logfile = new File(context.getApplicationContext().getCacheDir(), "snowflake.log");
try {
if (logfile.exists()) {
logfile.delete();
}
logfile.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
this.logfilePath = logfile.getAbsolutePath();
Random random = new Random();
boolean useAmpCache = random.nextInt(2) == 0;
startConnectionAttempt(useAmpCache, logfilePath);
watchLogFile(logfile);
}
private void startConnectionAttempt(boolean useAmpCache, @NonNull String logfilePath) {
//this is using the current, default Tor snowflake infrastructure
String target = getCdnFront("snowflake-target");
String front = getCdnFront("snowflake-front");
String stunServer = getCdnFront("snowflake-stun");
String ampCache = null;
if (useAmpCache) {
target = "https://snowflake-broker.torproject.net/";
ampCache = "https://cdn.ampproject.org/";
front = "www.google.com";
}
snowflakePort = IPtProxy.startSnowflake(stunServer, target, front, ampCache, logfilePath, false, false, true, 5);
Log.d(TAG, "startSnowflake running on port: " + snowflakePort);
}
private void retryConnectionAttempt(boolean useAmpCache) {
Log.d(TAG, ">> retryConnectionAttempt - " + (useAmpCache ? "amp cache" : "http domain fronting"));
stopConnectionAttempt();
startConnectionAttempt(useAmpCache, logfilePath);
}
private void watchLogFile(File logfile) {
final Vector<String> lastBuffer = new Vector<>();
logFileObserver = new FileObserver(logfile.getAbsolutePath()) {
@Override
public void onEvent(int event, @Nullable String name) {
if (FileObserver.MODIFY == event) {
try (Scanner scanner = new Scanner(logfile)) {
Vector<String> currentBuffer = new Vector<>();
while (scanner.hasNextLine()) {
currentBuffer.add(scanner.nextLine());
}
if (lastBuffer.size() < currentBuffer.size()) {
int startIndex = lastBuffer.size() > 0 ? lastBuffer.size() - 1 : 0;
int endIndex = currentBuffer.size() - 1;
Collection<String> newMessages = currentBuffer.subList(startIndex, endIndex);
for (String message : newMessages) {
logSnowflakeMessage(message);
}
lastBuffer.addAll(newMessages);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
}
};
logFileObserver.startWatching();
}
@Override
public void stop() {
stopConnectionAttempt();
if (logFileObserver != null) {
logFileObserver.stopWatching();
logFileObserver = null;
}
TorStatusObservable.getInstance().deleteObserver(this);
handlerThread.quit();
handler = null;
handlerThread = null;
}
private void stopConnectionAttempt() {
IPtProxy.stopSnowflake();
try {
TorStatusObservable.waitUntil(this::isSnowflakeOff, 10);
} catch (InterruptedException | TimeoutException e) {
e.printStackTrace();
}
snowflakePort = -1;
}
private boolean isSnowflakeOff() {
return TorStatusObservable.getSnowflakeStatus() == TorStatusObservable.SnowflakeStatus.STOPPED;
}
@Override
public String getTorrc() {
return "UseBridges 1\n" +
"ClientTransportPlugin snowflake socks5 127.0.0.1:" + snowflakePort + "\n" +
"Bridge snowflake 192.0.2.3:1";
}
private void loadCdnFronts(Context context) {
if (mFronts == null) {
mFronts = new HashMap<>();
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(context.getAssets().open("fronts")));
String line;
while (true) {
line = reader.readLine();
if (line == null) break;
String[] front = line.split(" ");
mFronts.put(front[0], front[1]);
Log.d(TAG, "front: " + front[0] + ", " + front[1]);
}
} catch (IOException e) {
e.printStackTrace();
}
}
@Nullable
private String getCdnFront(String service) {
if (mFronts != null) {
return mFronts.get(service);
}
return null;
}
private void logSnowflakeMessage(String message) {
Matcher matcher = SNOWFLAKE_LOG_TIMESTAMP_PATTERN.matcher(message);
if (matcher.matches()) {
try {
String strippedString = matcher.group(3).trim();
if (strippedString.length() > 0) {
TorStatusObservable.logSnowflakeMessage(contextRef.get(), strippedString);
}
} catch (IndexOutOfBoundsException | IllegalStateException | NullPointerException e) {
e.printStackTrace();
}
} else {
TorStatusObservable.logSnowflakeMessage(contextRef.get(), message);
}
}
@Override
public void propertyChange(PropertyChangeEvent evt) {
if(TorStatusObservable.PROPERTY_CHANGE.equals(evt.getPropertyName())) {
TorStatusObservable.SnowflakeStatus snowflakeStatus = TorStatusObservable.getSnowflakeStatus();
if (snowflakeStatus == this.snowflakeStatus) {
return;
}
if (snowflakeStatus == RETRY_HTTP_RENDEZVOUS) {
handler.post(() -> retryConnectionAttempt(false));
} else if (snowflakeStatus == RETRY_AMP_CACHE_RENDEZVOUS) {
handler.post(() -> retryConnectionAttempt(true));
}
this.snowflakeStatus = snowflakeStatus;
}
}
}
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