CellTracker.java 文件源码

/**
 *  Description:    This snippet sets a global variable (SharedPreference) to indicate
 *                  if Neighboring cells info CAN be obtained or has been obtained
 *                  previously. If it has been and suddenly there are none, we can
 *                  raise a flag of CID being suspicious.
 *
 *                  The logic is:
 *
 *                      IF NC has never been seen on device:
 *                          - NC list is NOT supported on this AOS/HW, so we do nothing.
 *                      IF NC has been seen before,
 *                          - NC list IS supported on this AOS/HW, so we set:
 *                              nc_list_present : "true"
 *                      IF NC list has been seen before AND current CID doesn't provide
 *                      one, we raise an alarm or flag.
 *
 *
 *  Notes:      a)  Not sure where to place this test, but let's try it here..
 *              b)  In TinyDB, the getBoolean() returns "false" by default, if empty.
 *
 *              c)   This will be called on every cell change (ref:  issue #346)
 *              d)  *** https://github.com/CellularPrivacy/Android-IMSI-Catcher-Detector/issues/383
 *
 *  Issue:
 *          [ ] We need a timer or "something" to reverse a positive detection once
 *              we're out and away from the fake BTS cell.
 *          [ ] We need to add this to EventLog
 *          [ ] We need to add detection tickers etc...
 *          [x] We need to use a global and persistent variable and not a system property
 *
 */
public void checkForNeighborCount(CellLocation location) {
    log.info("CheckForNeighborCount()");

    emptyNeighborCellsList = false;

    Integer neighborCellsCount = 0;
    if (tm != null && tm.getNeighboringCellInfo() != null) { // See # 383
        neighborCellsCount = tm.getNeighboringCellInfo().size();
    }

    // NC list present for that network type? (default is false)
    String ncListVariableByType = "nc_list_present_" + tm.getNetworkType();
    Boolean nclSupportedByNetwork = tinydb.getBoolean(ncListVariableByType);

    if (neighborCellsCount > 0) {
        log.debug("NeighboringCellInfo size: " + neighborCellsCount);
        if (!nclSupportedByNetwork)  {
            log.debug("Setting " + ncListVariableByType + " to: true");
            tinydb.putBoolean(ncListVariableByType, true);
        }
    } else if (neighborCellsCount == 0 && nclSupportedByNetwork) {
        // Detection 7a
        log.info("ALERT: No neighboring cells detected for CID: " + device.cell.getCellId());

        emptyNeighborCellsList = true;

        @Cleanup Realm realm = Realm.getDefaultInstance();
        dbHelper.toEventLog(realm, 4, "No neighboring cells detected"); // (DF_id, DF_desc)
    } else  {
        // Todo: remove cid string when working.
        log.debug("NC list not supported by this networkn type or not supported by AOS on this device. Nothing to do.");
        log.debug("Setting " + ncListVariableByType + " to: false");
        tinydb.putBoolean(ncListVariableByType, false);
    }
    setNotification();
}