NetGuard/app/src/main/java/eu/faircode/netguard/ActivityDns.java

package eu.faircode.netguard;

/*
    This file is part of NetGuard.

    NetGuard 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.

    NetGuard 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 NetGuard.  If not, see <http://www.gnu.org/licenses/>.

    Copyright 2015-2018 by Marcel Bokhorst (M66B)
*/

import android.content.Intent;
import android.content.pm.PackageManager;
import android.database.Cursor;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.util.Xml;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.widget.ListView;
import android.widget.Toast;

import org.xmlpull.v1.XmlSerializer;

import java.io.IOException;
import java.io.OutputStream;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

import androidx.appcompat.app.AppCompatActivity;

public class ActivityDns extends AppCompatActivity {
    private static final String TAG = "NetGuard.DNS";

    private static final int REQUEST_EXPORT = 1;

    private boolean running;
    private AdapterDns adapter = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        Util.setTheme(this);
        super.onCreate(savedInstanceState);
        setContentView(R.layout.resolving);

        getSupportActionBar().setTitle(R.string.setting_show_resolved);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);

        ListView lvDns = findViewById(R.id.lvDns);
        adapter = new AdapterDns(this, DatabaseHelper.getInstance(this).getDns());
        lvDns.setAdapter(adapter);

        running = true;
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.dns, menu);
        return true;
    }

    @Override
    public boolean onPrepareOptionsMenu(Menu menu) {
        PackageManager pm = getPackageManager();
        menu.findItem(R.id.menu_export).setEnabled(getIntentExport().resolveActivity(pm) != null);
        return super.onPrepareOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.menu_refresh:
                refresh();
                return true;

            case R.id.menu_cleanup:
                cleanup();
                return true;

            case R.id.menu_clear:
                Util.areYouSure(this, R.string.menu_clear, new Util.DoubtListener() {
                    @Override
                    public void onSure() {
                        clear();
                    }
                });
                return true;

            case R.id.menu_export:
                export();
                return true;
        }
        return false;
    }

    private void refresh() {
        updateAdapter();
    }

    private void cleanup() {
        new AsyncTask<Object, Object, Object>() {
            @Override
            protected Long doInBackground(Object... objects) {
                Log.i(TAG, "Cleanup DNS");
                DatabaseHelper.getInstance(ActivityDns.this).cleanupDns();
                return null;
            }

            @Override
            protected void onPostExecute(Object result) {
                ServiceSinkhole.reload("DNS cleanup", ActivityDns.this, false);
                updateAdapter();
            }
        }.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
    }

    private void clear() {
        new AsyncTask<Object, Object, Object>() {
            @Override
            protected Long doInBackground(Object... objects) {
                Log.i(TAG, "Clear DNS");
                DatabaseHelper.getInstance(ActivityDns.this).clearDns();
                return null;
            }

            @Override
            protected void onPostExecute(Object result) {
                ServiceSinkhole.reload("DNS clear", ActivityDns.this, false);
                updateAdapter();
            }
        }.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
    }

    private void export() {
        startActivityForResult(getIntentExport(), REQUEST_EXPORT);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        Log.i(TAG, "onActivityResult request=" + requestCode + " result=" + requestCode + " ok=" + (resultCode == RESULT_OK));
        if (requestCode == REQUEST_EXPORT) {
            if (resultCode == RESULT_OK && data != null)
                handleExport(data);
        }
    }

    private Intent getIntentExport() {
        Intent intent = new Intent(Intent.ACTION_CREATE_DOCUMENT);
        intent.addCategory(Intent.CATEGORY_OPENABLE);
        intent.setType("*/*"); // text/xml
        intent.putExtra(Intent.EXTRA_TITLE, "netguard_dns_" + new SimpleDateFormat("yyyyMMdd").format(new Date().getTime()) + ".xml");
        return intent;
    }

    private void handleExport(final Intent data) {
        new AsyncTask<Object, Object, Throwable>() {
            @Override
            protected Throwable doInBackground(Object... objects) {
                OutputStream out = null;
                try {
                    Uri target = data.getData();
                    Log.i(TAG, "Writing URI=" + target);
                    out = getContentResolver().openOutputStream(target);
                    xmlExport(out);
                    return null;
                } catch (Throwable ex) {
                    Log.e(TAG, ex.toString() + "\n" + Log.getStackTraceString(ex));
                    return ex;
                } finally {
                    if (out != null)
                        try {
                            out.close();
                        } catch (IOException ex) {
                            Log.e(TAG, ex.toString() + "\n" + Log.getStackTraceString(ex));
                        }
                }
            }

            @Override
            protected void onPostExecute(Throwable ex) {
                if (running) {
                    if (ex == null)
                        Toast.makeText(ActivityDns.this, R.string.msg_completed, Toast.LENGTH_LONG).show();
                    else
                        Toast.makeText(ActivityDns.this, ex.toString(), Toast.LENGTH_LONG).show();
                }
            }
        }.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
    }

    private void xmlExport(OutputStream out) throws IOException {
        XmlSerializer serializer = Xml.newSerializer();
        serializer.setOutput(out, "UTF-8");
        serializer.startDocument(null, true);
        serializer.setFeature("http://xmlpull.org/v1/doc/features.html#indent-output", true);
        serializer.startTag(null, "netguard");

        DateFormat df = new SimpleDateFormat("E, d MMM yyyy HH:mm:ss Z", Locale.US); // RFC 822

        Cursor cursor = DatabaseHelper.getInstance(this).getDns();
        int colTime = cursor.getColumnIndex("time");
        int colQName = cursor.getColumnIndex("qname");
        int colAName = cursor.getColumnIndex("aname");
        int colResource = cursor.getColumnIndex("resource");
        int colTTL = cursor.getColumnIndex("ttl");
        while (cursor.moveToNext()) {
            long time = cursor.getLong(colTime);
            String qname = cursor.getString(colQName);
            String aname = cursor.getString(colAName);
            String resource = cursor.getString(colResource);
            int ttl = cursor.getInt(colTTL);

            serializer.startTag(null, "dns");
            serializer.attribute(null, "time", df.format(time));
            serializer.attribute(null, "qname", qname);
            serializer.attribute(null, "aname", aname);
            serializer.attribute(null, "resource", resource);
            serializer.attribute(null, "ttl", Integer.toString(ttl));
            serializer.endTag(null, "dns");
        }
        cursor.close();

        serializer.endTag(null, "netguard");
        serializer.endDocument();
        serializer.flush();
    }

    private void updateAdapter() {
        if (adapter != null)
            adapter.changeCursor(DatabaseHelper.getInstance(this).getDns());
    }

    @Override
    protected void onDestroy() {
        running = false;
        adapter = null;
        super.onDestroy();
    }
}