Revert "DO NOT MERGE: Remove SMS shortcode warning feature."

This reverts commit b1fc08ca082db8ecad54c792485ff7915e3513ce.

2 files changed, 373 insertions, 9 deletions

diff --git a/telephony/java/com/android/internal/telephony/SMSDispatcher.java b/telephony/java/com/android/internal/telephony/SMSDispatcher.java
index 07d733e..c5af396 100644
--- a/telephony/java/com/android/internal/telephony/SMSDispatcher.java
+++ b/telephony/java/com/android/internal/telephony/SMSDispatcher.java
@@ -906,18 +906,61 @@ public abstract class SMSDispatcher extends Handler {
         SmsTracker tracker = new SmsTracker(map, sentIntent, deliveryIntent, appPackage,
                 PhoneNumberUtils.extractNetworkPortion(destAddr));
 
-        // check for excessive outgoing SMS usage by this app
-        if (!mUsageMonitor.check(appPackage, SINGLE_PART_SMS)) {
-            sendMessage(obtainMessage(EVENT_SEND_LIMIT_REACHED_CONFIRMATION, tracker));
-            return;
-        }
+        // checkDestination() returns true if the destination is not a premium short code or the
+        // sending app is approved to send to short codes. Otherwise, a message is sent to our
+        // handler with the SmsTracker to request user confirmation before sending.
+        if (checkDestination(tracker)) {
+            // check for excessive outgoing SMS usage by this app
+            if (!mUsageMonitor.check(appPackage, SINGLE_PART_SMS)) {
+                sendMessage(obtainMessage(EVENT_SEND_LIMIT_REACHED_CONFIRMATION, tracker));
+                return;
+            }
 
-        int ss = mPhone.getServiceState().getState();
+            int ss = mPhone.getServiceState().getState();
 
-        if (ss != ServiceState.STATE_IN_SERVICE) {
-            handleNotInService(ss, tracker.mSentIntent);
+            if (ss != ServiceState.STATE_IN_SERVICE) {
+                handleNotInService(ss, tracker.mSentIntent);
+            } else {
+                sendSms(tracker);
+            }
+        }
+    }
+
+    /**
+     * Check if destination is a potential premium short code and sender is not pre-approved to
+     * send to short codes.
+     *
+     * @param tracker the tracker for the SMS to send
+     * @return true if the destination is approved; false if user confirmation event was sent
+     */
+    boolean checkDestination(SmsTracker tracker) {
+        if (mContext.checkCallingOrSelfPermission(SEND_SMS_NO_CONFIRMATION_PERMISSION)
+                == PackageManager.PERMISSION_GRANTED) {
+            return true;            // app is pre-approved to send to short codes
         } else {
-            sendSms(tracker);
+            String countryIso = mTelephonyManager.getSimCountryIso();
+            if (countryIso == null || countryIso.length() != 2) {
+                Log.e(TAG, "Can't get SIM country code: trying network country code");
+                countryIso = mTelephonyManager.getNetworkCountryIso();
+            }
+
+            switch (mUsageMonitor.checkDestination(tracker.mDestAddress, countryIso)) {
+                case SmsUsageMonitor.CATEGORY_POSSIBLE_PREMIUM_SHORT_CODE:
+                    sendMessage(obtainMessage(EVENT_CONFIRM_SEND_TO_POSSIBLE_PREMIUM_SHORT_CODE,
+                            tracker));
+                    return false;   // wait for user confirmation before sending
+
+                case SmsUsageMonitor.CATEGORY_PREMIUM_SHORT_CODE:
+                    sendMessage(obtainMessage(EVENT_CONFIRM_SEND_TO_PREMIUM_SHORT_CODE,
+                            tracker));
+                    return false;   // wait for user confirmation before sending
+
+                case SmsUsageMonitor.CATEGORY_NOT_SHORT_CODE:
+                case SmsUsageMonitor.CATEGORY_FREE_SHORT_CODE:
+                case SmsUsageMonitor.CATEGORY_STANDARD_SHORT_CODE:
+                default:
+                    return true;    // destination is not a premium short code
+            }
         }
     }
 
diff --git a/telephony/java/com/android/internal/telephony/SmsUsageMonitor.java b/telephony/java/com/android/internal/telephony/SmsUsageMonitor.java
index 4a4485d..1804d97 100644
--- a/telephony/java/com/android/internal/telephony/SmsUsageMonitor.java
+++ b/telephony/java/com/android/internal/telephony/SmsUsageMonitor.java
@@ -60,17 +60,177 @@ public class SmsUsageMonitor {
     /** Default number of SMS sent in checking period without user permission. */
     private static final int DEFAULT_SMS_MAX_COUNT = 30;
 
+    /** Return value from {@link #checkDestination} for regular phone numbers. */
+    static final int CATEGORY_NOT_SHORT_CODE = 0;
+
+    /** Return value from {@link #checkDestination} for free (no cost) short codes. */
+    static final int CATEGORY_FREE_SHORT_CODE = 1;
+
+    /** Return value from {@link #checkDestination} for standard rate (non-premium) short codes. */
+    static final int CATEGORY_STANDARD_SHORT_CODE = 2;
+
+    /** Return value from {@link #checkDestination} for possible premium short codes. */
+    static final int CATEGORY_POSSIBLE_PREMIUM_SHORT_CODE = 3;
+
+    /** Return value from {@link #checkDestination} for premium short codes. */
+    static final int CATEGORY_PREMIUM_SHORT_CODE = 4;
+
     private final int mCheckPeriod;
     private final int mMaxAllowed;
 
     private final HashMap<String, ArrayList<Long>> mSmsStamp =
             new HashMap<String, ArrayList<Long>>();
 
+    /** Context for retrieving regexes from XML resource. */
+    private final Context mContext;
+
+    /** Country code for the cached short code pattern matcher. */
+    private String mCurrentCountry;
+
+    /** Cached short code pattern matcher for {@link #mCurrentCountry}. */
+    private ShortCodePatternMatcher mCurrentPatternMatcher;
+
+    /** Cached short code regex patterns from secure settings for {@link #mCurrentCountry}. */
+    private String mSettingsShortCodePatterns;
+
+    /** Handler for responding to content observer updates. */
+    private final SettingsObserverHandler mSettingsObserverHandler;
+
+    /** XML tag for root element. */
+    private static final String TAG_SHORTCODES = "shortcodes";
+
+    /** XML tag for short code patterns for a specific country. */
+    private static final String TAG_SHORTCODE = "shortcode";
+
+    /** XML attribute for the country code. */
+    private static final String ATTR_COUNTRY = "country";
+
+    /** XML attribute for the short code regex pattern. */
+    private static final String ATTR_PATTERN = "pattern";
+
+    /** XML attribute for the premium short code regex pattern. */
+    private static final String ATTR_PREMIUM = "premium";
+
+    /** XML attribute for the free short code regex pattern. */
+    private static final String ATTR_FREE = "free";
+
+    /** XML attribute for the standard rate short code regex pattern. */
+    private static final String ATTR_STANDARD = "standard";
+
+    /**
+     * SMS short code regex pattern matcher for a specific country.
+     */
+    private static final class ShortCodePatternMatcher {
+        private final Pattern mShortCodePattern;
+        private final Pattern mPremiumShortCodePattern;
+        private final Pattern mFreeShortCodePattern;
+        private final Pattern mStandardShortCodePattern;
+
+        ShortCodePatternMatcher(String shortCodeRegex, String premiumShortCodeRegex,
+                String freeShortCodeRegex, String standardShortCodeRegex) {
+            mShortCodePattern = (shortCodeRegex != null ? Pattern.compile(shortCodeRegex) : null);
+            mPremiumShortCodePattern = (premiumShortCodeRegex != null ?
+                    Pattern.compile(premiumShortCodeRegex) : null);
+            mFreeShortCodePattern = (freeShortCodeRegex != null ?
+                    Pattern.compile(freeShortCodeRegex) : null);
+            mStandardShortCodePattern = (standardShortCodeRegex != null ?
+                    Pattern.compile(standardShortCodeRegex) : null);
+        }
+
+        int getNumberCategory(String phoneNumber) {
+            if (mFreeShortCodePattern != null && mFreeShortCodePattern.matcher(phoneNumber)
+                    .matches()) {
+                return CATEGORY_FREE_SHORT_CODE;
+            }
+            if (mStandardShortCodePattern != null && mStandardShortCodePattern.matcher(phoneNumber)
+                    .matches()) {
+                return CATEGORY_STANDARD_SHORT_CODE;
+            }
+            if (mPremiumShortCodePattern != null && mPremiumShortCodePattern.matcher(phoneNumber)
+                    .matches()) {
+                return CATEGORY_PREMIUM_SHORT_CODE;
+            }
+            if (mShortCodePattern != null && mShortCodePattern.matcher(phoneNumber).matches()) {
+                return CATEGORY_POSSIBLE_PREMIUM_SHORT_CODE;
+            }
+            return CATEGORY_NOT_SHORT_CODE;
+        }
+    }
+
+    /**
+     * Observe the secure setting for updated regex patterns.
+     */
+    private static class SettingsObserver extends ContentObserver {
+        private final int mWhat;
+        private final Handler mHandler;
+
+        SettingsObserver(Handler handler, int what) {
+            super(handler);
+            mHandler = handler;
+            mWhat = what;
+        }
+
+        @Override
+        public void onChange(boolean selfChange) {
+            mHandler.obtainMessage(mWhat).sendToTarget();
+        }
+    }
+
+    /**
+     * Handler to update regex patterns when secure setting for the current country is updated.
+     */
+    private class SettingsObserverHandler extends Handler {
+        /** Current content observer, or null. */
+        SettingsObserver mSettingsObserver;
+
+        /** Current country code to watch for settings updates. */
+        private String mCountryIso;
+
+        /** Request to start observing a secure setting. */
+        static final int OBSERVE_SETTING = 1;
+
+        /** Handler event for updated secure settings. */
+        static final int SECURE_SETTINGS_CHANGED = 2;
+
+        /** Send a message to this handler requesting to observe the setting for a new country. */
+        void observeSettingForCountry(String countryIso) {
+            obtainMessage(OBSERVE_SETTING, countryIso).sendToTarget();
+        }
+
+        @Override
+        public void handleMessage(Message msg) {
+            switch (msg.what) {
+                case OBSERVE_SETTING:
+                    if (msg.obj != null && msg.obj instanceof String) {
+                        mCountryIso = (String) msg.obj;
+                        String settingName = getSettingNameForCountry(mCountryIso);
+                        ContentResolver resolver = mContext.getContentResolver();
+
+                        if (mSettingsObserver != null) {
+                            if (VDBG) log("Unregistering old content observer");
+                            resolver.unregisterContentObserver(mSettingsObserver);
+                        }
+
+                        mSettingsObserver = new SettingsObserver(this, SECURE_SETTINGS_CHANGED);
+                        resolver.registerContentObserver(
+                                Settings.Secure.getUriFor(settingName), false, mSettingsObserver);
+                        if (VDBG) log("Registered content observer for " + settingName);
+                    }
+                    break;
+
+                case SECURE_SETTINGS_CHANGED:
+                    loadPatternsFromSettings(mCountryIso);
+                    break;
+            }
+        }
+    }
+
     /**
      * Create SMS usage monitor.
      * @param context the context to use to load resources and get TelephonyManager service
      */
     public SmsUsageMonitor(Context context) {
+        mContext = context;
         ContentResolver resolver = context.getContentResolver();
 
         mMaxAllowed = Settings.Secure.getInt(resolver,
@@ -80,6 +240,83 @@ public class SmsUsageMonitor {
         mCheckPeriod = Settings.Secure.getInt(resolver,
                 Settings.Secure.SMS_OUTGOING_CHECK_INTERVAL_MS,
                 DEFAULT_SMS_CHECK_PERIOD);
+
+        mSettingsObserverHandler = new SettingsObserverHandler();
+    }
+
+    /**
+     * Return a pattern matcher object for the specified country.
+     * @param country the country to search for
+     * @return a {@link ShortCodePatternMatcher} for the specified country, or null if not found
+     */
+    private ShortCodePatternMatcher getPatternMatcher(String country) {
+        int id = com.android.internal.R.xml.sms_short_codes;
+        XmlResourceParser parser = mContext.getResources().getXml(id);
+
+        try {
+            return getPatternMatcher(country, parser);
+        } catch (XmlPullParserException e) {
+            Log.e(TAG, "XML parser exception reading short code pattern resource", e);
+        } catch (IOException e) {
+            Log.e(TAG, "I/O exception reading short code pattern resource", e);
+        } finally {
+            parser.close();
+        }
+        return null;    // country not found
+    }
+
+    /**
+     * Return a pattern matcher object for the specified country from a secure settings string.
+     * @return a {@link ShortCodePatternMatcher} for the specified country, or null if not found
+     */
+    private static ShortCodePatternMatcher getPatternMatcher(String country, String settingsPattern) {
+        // embed pattern tag into an XML document.
+        String document = "<shortcodes>" + settingsPattern + "</shortcodes>";
+        if (VDBG) log("loading updated patterns from: " + document);
+
+        try {
+            XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
+            XmlPullParser parser = factory.newPullParser();
+            parser.setInput(new StringReader(document));
+            return getPatternMatcher(country, parser);
+        } catch (XmlPullParserException e) {
+            Log.e(TAG, "XML parser exception reading short code pattern from settings", e);
+        } catch (IOException e) {
+            Log.e(TAG, "I/O exception reading short code pattern from settings", e);
+        }
+        return null;    // country not found
+    }
+
+    /**
+     * Return a pattern matcher object for the specified country and pattern XML parser.
+     * @param country the country to search for
+     * @return a {@link ShortCodePatternMatcher} for the specified country, or null if not found
+     */
+    private static ShortCodePatternMatcher getPatternMatcher(String country, XmlPullParser parser)
+            throws XmlPullParserException, IOException
+    {
+        XmlUtils.beginDocument(parser, TAG_SHORTCODES);
+
+        while (true) {
+            XmlUtils.nextElement(parser);
+
+            String element = parser.getName();
+            if (element == null) break;
+
+            if (element.equals(TAG_SHORTCODE)) {
+                String currentCountry = parser.getAttributeValue(null, ATTR_COUNTRY);
+                if (country.equals(currentCountry)) {
+                    String pattern = parser.getAttributeValue(null, ATTR_PATTERN);
+                    String premium = parser.getAttributeValue(null, ATTR_PREMIUM);
+                    String free = parser.getAttributeValue(null, ATTR_FREE);
+                    String standard = parser.getAttributeValue(null, ATTR_STANDARD);
+                    return new ShortCodePatternMatcher(pattern, premium, free, standard);
+                }
+            } else {
+                Log.e(TAG, "Error: skipping unknown XML tag " + element);
+            }
+        }
+        return null;    // country not found
     }
 
     /** Clear the SMS application list for disposal. */
@@ -112,6 +349,90 @@ public class SmsUsageMonitor {
     }
 
     /**
+     * Check if the destination is a possible premium short code.
+     * NOTE: the caller is expected to strip non-digits from the destination number with
+     * {@link PhoneNumberUtils#extractNetworkPortion} before calling this method.
+     * This happens in {@link SMSDispatcher#sendRawPdu} so that we use the same phone number
+     * for testing and in the user confirmation dialog if the user needs to confirm the number.
+     * This makes it difficult for malware to fool the user or the short code pattern matcher
+     * by using non-ASCII characters to make the number appear to be different from the real
+     * destination phone number.
+     *
+     * @param destAddress the destination address to test for possible short code
+     * @return {@link #CATEGORY_NOT_SHORT_CODE}, {@link #CATEGORY_FREE_SHORT_CODE},
+     *  {@link #CATEGORY_POSSIBLE_PREMIUM_SHORT_CODE}, or {@link #CATEGORY_PREMIUM_SHORT_CODE}.
+     */
+    public int checkDestination(String destAddress, String countryIso) {
+        synchronized (mSettingsObserverHandler) {
+            // always allow emergency numbers
+            if (PhoneNumberUtils.isEmergencyNumber(destAddress, countryIso)) {
+                return CATEGORY_NOT_SHORT_CODE;
+            }
+
+            ShortCodePatternMatcher patternMatcher = null;
+
+            if (countryIso != null) {
+                // query secure settings and initialize content observer for updated regex patterns
+                if (mCurrentCountry == null || !countryIso.equals(mCurrentCountry)) {
+                    loadPatternsFromSettings(countryIso);
+                    mSettingsObserverHandler.observeSettingForCountry(countryIso);
+                }
+
+                if (countryIso.equals(mCurrentCountry)) {
+                    patternMatcher = mCurrentPatternMatcher;
+                } else {
+                    patternMatcher = getPatternMatcher(countryIso);
+                    mCurrentCountry = countryIso;
+                    mCurrentPatternMatcher = patternMatcher;    // may be null if not found
+                }
+            }
+
+            if (patternMatcher != null) {
+                return patternMatcher.getNumberCategory(destAddress);
+            } else {
+                // Generic rule: numbers of 5 digits or less are considered potential short codes
+                Log.e(TAG, "No patterns for \"" + countryIso + "\": using generic short code rule");
+                if (destAddress.length() <= 5) {
+                    return CATEGORY_POSSIBLE_PREMIUM_SHORT_CODE;
+                } else {
+                    return CATEGORY_NOT_SHORT_CODE;
+                }
+            }
+        }
+    }
+
+    private static String getSettingNameForCountry(String countryIso) {
+        return Settings.Secure.SMS_SHORT_CODES_PREFIX + countryIso;
+    }
+
+    /**
+     * Load regex patterns from secure settings if present.
+     * @param countryIso the country to search for
+     */
+    void loadPatternsFromSettings(String countryIso) {
+        synchronized (mSettingsObserverHandler) {
+            if (VDBG) log("loadPatternsFromSettings(" + countryIso + ") called");
+            String settingsPatterns = Settings.Secure.getString(
+                    mContext.getContentResolver(), getSettingNameForCountry(countryIso));
+            if (settingsPatterns != null && !settingsPatterns.equals(
+                    mSettingsShortCodePatterns)) {
+                // settings pattern string has changed: update the pattern matcher
+                mSettingsShortCodePatterns = settingsPatterns;
+                ShortCodePatternMatcher matcher = getPatternMatcher(countryIso, settingsPatterns);
+                if (matcher != null) {
+                    mCurrentCountry = countryIso;
+                    mCurrentPatternMatcher = matcher;
+                }
+            } else if (settingsPatterns == null && mSettingsShortCodePatterns != null) {
+                // pattern string was removed: caller will load default patterns from XML resource
+                mCurrentCountry = null;
+                mCurrentPatternMatcher = null;
+                mSettingsShortCodePatterns = null;
+            }
+        }
+    }
+
+    /**
      * Remove keys containing only old timestamps. This can happen if an SMS app is used
      * to send messages and then uninstalled.
      */