Java tutorial
/* * Copyright 2012 The Stanford MobiSocial Laboratory * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package mobisocial.musubi.nearby.scanner; import gnu.trove.list.array.TByteArrayList; import java.io.BufferedReader; import java.io.InputStream; import java.io.InputStreamReader; import java.nio.ByteBuffer; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import java.security.spec.AlgorithmParameterSpec; import java.util.Arrays; import java.util.HashSet; import java.util.List; import javax.crypto.Cipher; import javax.crypto.spec.IvParameterSpec; import javax.crypto.spec.SecretKeySpec; import mobisocial.crypto.IBHashedIdentity.Authority; import mobisocial.musubi.nearby.item.NearbyFeed; import mobisocial.musubi.nearby.item.NearbyItem; import mobisocial.musubi.nearby.location.GridHandler; import mobisocial.musubi.ui.MusubiBaseActivity; import mobisocial.musubi.util.MyLocation; import mobisocial.musubi.util.Util; import org.apache.http.HttpResponse; import org.apache.http.client.methods.HttpPost; import org.apache.http.entity.StringEntity; import org.apache.http.impl.client.DefaultHttpClient; import org.json.JSONArray; import org.json.JSONObject; import android.content.Context; import android.location.Location; import android.net.Uri; import android.util.Base64; import android.util.Log; import org.javatuples.Pair; /** * Pings a server with GPS information to search for nearby items. */ public class GpsScannerTask extends NearbyScannerTask { private final boolean DBG = MusubiBaseActivity.DBG; private final Context mContext; private final String mmPassword; private final MyLocation mmMyLocation; private boolean mmLocationScanComplete = false; private Location mmLocation = null; public GpsScannerTask(Context context, String password) { mmPassword = password; mmMyLocation = new MyLocation(); mContext = context; } @Override protected void onPreExecute() { mmMyLocation.getLocation(mContext, mmLocationResult); } @Override protected List<NearbyItem> doInBackground(Void... params) { if (DBG) Log.d(TAG, "Scanning for nearby gps..."); while (!mmLocationScanComplete) { synchronized (mmLocationResult) { if (!mmLocationScanComplete) { try { if (DBG) Log.d(TAG, "Waiting for location results..."); mmLocationResult.wait(); } catch (InterruptedException e) { } } } } if (DBG) Log.d(TAG, "Got location " + mmLocation); if (isCancelled()) { return null; } try { if (DBG) Log.d(TAG, "Querying gps server..."); Uri uri = Uri.parse("http://bumblebee.musubi.us:6253/nearbyapi/0/findgroup"); StringBuffer sb = new StringBuffer(); DefaultHttpClient client = new DefaultHttpClient(); HttpPost httpPost = new HttpPost(uri.toString()); httpPost.addHeader("Content-Type", "application/json"); JSONArray buckets = new JSONArray(); double lat = mmLocation.getLatitude(); double lng = mmLocation.getLongitude(); long[] coords = GridHandler.getGridCoords(lat, lng, 5280 / 2); Log.i(TAG, "coords: " + Arrays.toString(coords)); //TODO: encrypt coords with mmPassword for (long c : coords) { MessageDigest md; try { byte[] obfuscate = ("sadsalt193s" + mmPassword).getBytes(); md = MessageDigest.getInstance("SHA-256"); ByteBuffer b = ByteBuffer.allocate(8 + obfuscate.length); b.putLong(c); b.put(obfuscate); String secret_bucket = Base64.encodeToString(md.digest(b.array()), Base64.DEFAULT); buckets.put(buckets.length(), secret_bucket); } catch (NoSuchAlgorithmException e) { throw new RuntimeException("your platform does not support sha256", e); } } Log.i(TAG, "buckets: " + buckets); httpPost.setEntity(new StringEntity(buckets.toString())); try { HttpResponse execute = client.execute(httpPost); InputStream content = execute.getEntity().getContent(); BufferedReader buffer = new BufferedReader(new InputStreamReader(content)); String s = ""; while ((s = buffer.readLine()) != null) { if (isCancelled()) { return null; } sb.append(s); } } catch (Exception e) { e.printStackTrace(); } HashSet<Pair<TByteArrayList, TByteArrayList>> dupes = new HashSet<Pair<TByteArrayList, TByteArrayList>>(); String response = sb.toString(); JSONArray groupsJSON = new JSONArray(response); Log.d(TAG, "Got " + groupsJSON.length() + " groups"); for (int i = 0; i < groupsJSON.length(); i++) { try { String s_enc_data = groupsJSON.get(i).toString(); byte[] enc_data = Base64.decode(s_enc_data, Base64.DEFAULT); byte[] key = Util.sha256(("happysalt621" + mmPassword).getBytes()); byte[] data; Cipher cipher; AlgorithmParameterSpec iv_spec; SecretKeySpec sks; try { cipher = Cipher.getInstance("AES/CBC/PKCS7Padding"); } catch (Exception e) { throw new RuntimeException("AES not supported on this platform", e); } try { iv_spec = new IvParameterSpec(enc_data, 0, 16); sks = new SecretKeySpec(key, "AES"); cipher.init(Cipher.DECRYPT_MODE, sks, iv_spec); } catch (Exception e) { throw new RuntimeException("bad iv or key", e); } try { data = cipher.doFinal(enc_data, 16, enc_data.length - 16); } catch (Exception e) { throw new RuntimeException("body decryption failed", e); } JSONObject group = new JSONObject(new String(data)); String group_name = group.getString("group_name"); byte[] group_capability = Base64.decode(group.getString("group_capability"), Base64.DEFAULT); String sharer_name = group.getString("sharer_name"); byte[] sharer_hash = Base64.decode(group.getString("sharer_hash"), Base64.DEFAULT); byte[] thumbnail = null; if (group.has("thumbnail")) thumbnail = Base64.decode(group.getString("thumbnail"), Base64.DEFAULT); int member_count = group.getInt("member_count"); int sharer_type = group.getInt("sharer_type"); Pair<TByteArrayList, TByteArrayList> p = Pair.with(new TByteArrayList(sharer_hash), new TByteArrayList(group_capability)); if (dupes.contains(p)) continue; dupes.add(p); addNearbyItem(new NearbyFeed(mContext, group_name, group_capability, sharer_name, Authority.values()[sharer_type], sharer_hash, thumbnail, member_count)); } catch (Throwable e) { Log.e(TAG, "Failed to parse group " + i, e); } } } catch (Exception e) { if (DBG) Log.d(TAG, "Error searching nearby feeds", e); } return null; } private final MyLocation.LocationResult mmLocationResult = new MyLocation.LocationResult() { @Override public void gotLocation(final Location location) { if (DBG) Log.d(TAG, "got location"); mmLocation = location; mmLocationScanComplete = true; synchronized (mmLocationResult) { mmLocationResult.notify(); } } }; }