src/frontends/android/app/src/main/java/org/strongswan/android/data/LogContentProvider.java

   1 /*
   2  * Copyright (C) 2012 Tobias Brunner
   3  * Hochschule fuer Technik Rapperswil
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License as published by the
   7  * Free Software Foundation; either version 2 of the License, or (at your
   8  * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  12  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * for more details.
  14  */
  15
  16 package org.strongswan.android.data;
  17
  18 import java.io.File;
  19 import java.io.FileNotFoundException;
  20 import java.security.NoSuchAlgorithmException;
  21 import java.security.SecureRandom;
  22 import java.util.concurrent.ConcurrentHashMap;
  23
  24 import org.strongswan.android.logic.CharonVpnService;
  25
  26 import android.content.ContentProvider;
  27 import android.content.ContentValues;
  28 import android.database.Cursor;
  29 import android.database.MatrixCursor;
  30 import android.net.Uri;
  31 import android.os.ParcelFileDescriptor;
  32 import android.os.SystemClock;
  33 import android.provider.OpenableColumns;
  34
  35 public class LogContentProvider extends ContentProvider
  36 {
  37         private static final String AUTHORITY = "org.strongswan.android.content.log";
  38         /* an Uri is valid for 30 minutes */
  39         private static final long URI_VALIDITY = 30 * 60 * 1000;
  40         private static ConcurrentHashMap<Uri, Long> mUris = new ConcurrentHashMap<Uri, Long>();
  41         private File mLogFile;
  42
  43         public LogContentProvider()
  44         {
  45         }
  46
  47         @Override
  48         public boolean onCreate()
  49         {
  50                 mLogFile = new File(getContext().getFilesDir(), CharonVpnService.LOG_FILE);
  51                 return true;
  52         }
  53
  54         /**
  55          * The log file can only be accessed by Uris created with this method
  56          * @return null if failed to create the Uri
  57          */
  58         public static Uri createContentUri()
  59         {
  60                 SecureRandom random;
  61                 try
  62                 {
  63                         random = SecureRandom.getInstance("SHA1PRNG");
  64                 }
  65                 catch (NoSuchAlgorithmException e)
  66                 {
  67                         return null;
  68                 }
  69                 Uri uri = Uri.parse("content://" + AUTHORITY + "/" + random.nextLong());
  70                 mUris.put(uri, SystemClock.uptimeMillis());
  71                 return uri;
  72         }
  73
  74         @Override
  75         public String getType(Uri uri)
  76         {
  77                 /* MIME type for our log file */
  78                 return "text/plain";
  79         }
  80
  81         @Override
  82         public Cursor query(Uri uri, String[] projection, String selection,
  83                                                 String[] selectionArgs, String sortOrder)
  84         {
  85                 /* this is called by apps to find out the name and size of the file.
  86                  * since we only provide a single file this is simple to implement */
  87                 if (projection == null || projection.length < 1)
  88                 {
  89                         return null;
  90                 }
  91                 Long timestamp = mUris.get(uri);
  92                 if (timestamp == null)
  93                 {       /* don't check the validity as this information is not really private */
  94                         return null;
  95                 }
  96                 MatrixCursor cursor = new MatrixCursor(projection, 1);
  97                 if (OpenableColumns.DISPLAY_NAME.equals(cursor.getColumnName(0)))
  98                 {
  99                         cursor.newRow().add(CharonVpnService.LOG_FILE);
 100                 }
 101                 else if (OpenableColumns.SIZE.equals(cursor.getColumnName(0)))
 102                 {
 103                         cursor.newRow().add(mLogFile.length());
 104                 }
 105                 else
 106                 {
 107                         return null;
 108                 }
 109                 return cursor;
 110         }
 111
 112         @Override
 113         public ParcelFileDescriptor openFile(Uri uri, String mode) throws FileNotFoundException
 114         {
 115                 Long timestamp = mUris.get(uri);
 116                 if (timestamp != null)
 117                 {
 118                         long elapsed = SystemClock.uptimeMillis() - timestamp;
 119                         if (elapsed > 0 && elapsed < URI_VALIDITY)
 120                         {       /* we fail if clock wrapped, should happen rarely though */
 121                                 return ParcelFileDescriptor.open(mLogFile, ParcelFileDescriptor.MODE_CREATE | ParcelFileDescriptor.MODE_READ_ONLY);
 122                         }
 123                         mUris.remove(uri);
 124                 }
 125                 return super.openFile(uri, mode);
 126         }
 127
 128         @Override
 129         public Uri insert(Uri uri, ContentValues values)
 130         {
 131                 /* not supported */
 132                 return null;
 133         }
 134
 135         @Override
 136         public int delete(Uri uri, String selection, String[] selectionArgs)
 137         {
 138                 /* not supported */
 139                 return 0;
 140         }
 141
 142         @Override
 143         public int update(Uri uri, ContentValues values, String selection,
 144                                           String[] selectionArgs)
 145         {
 146                 /* not supported */
 147                 return 0;
 148         }
 149 }