| /* |
| * Copyright (C) 2012 The Android Open Source Project |
| * |
| * 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 com.android.internal.telephony.gsm; |
| |
| import static android.telephony.SmsCbEtwsInfo.ETWS_WARNING_TYPE_EARTHQUAKE; |
| import static android.telephony.SmsCbEtwsInfo.ETWS_WARNING_TYPE_EARTHQUAKE_AND_TSUNAMI; |
| import static android.telephony.SmsCbEtwsInfo.ETWS_WARNING_TYPE_OTHER_EMERGENCY; |
| import static android.telephony.SmsCbEtwsInfo.ETWS_WARNING_TYPE_TEST_MESSAGE; |
| import static android.telephony.SmsCbEtwsInfo.ETWS_WARNING_TYPE_TSUNAMI; |
| |
| import android.annotation.NonNull; |
| import android.content.Context; |
| import android.content.res.Resources; |
| import android.telephony.SmsCbLocation; |
| import android.telephony.SmsCbMessage; |
| import android.util.Pair; |
| import android.util.Slog; |
| |
| import com.android.internal.R; |
| import com.android.internal.telephony.CbGeoUtils; |
| import com.android.internal.telephony.CbGeoUtils.Circle; |
| import com.android.internal.telephony.CbGeoUtils.Geometry; |
| import com.android.internal.telephony.CbGeoUtils.LatLng; |
| import com.android.internal.telephony.CbGeoUtils.Polygon; |
| import com.android.internal.telephony.GsmAlphabet; |
| import com.android.internal.telephony.SmsConstants; |
| import com.android.internal.telephony.gsm.GsmSmsCbMessage.GeoFencingTriggerMessage.CellBroadcastIdentity; |
| import com.android.internal.telephony.gsm.SmsCbHeader.DataCodingScheme; |
| |
| import java.io.UnsupportedEncodingException; |
| import java.util.ArrayList; |
| import java.util.List; |
| import java.util.stream.Collectors; |
| |
| /** |
| * Parses a GSM or UMTS format SMS-CB message into an {@link SmsCbMessage} object. The class is |
| * public because {@link #createSmsCbMessage(SmsCbLocation, byte[][])} is used by some test cases. |
| */ |
| public class GsmSmsCbMessage { |
| private static final String TAG = GsmSmsCbMessage.class.getSimpleName(); |
| |
| private static final char CARRIAGE_RETURN = 0x0d; |
| |
| private static final int PDU_BODY_PAGE_LENGTH = 82; |
| |
| /** Utility class with only static methods. */ |
| private GsmSmsCbMessage() { } |
| |
| /** |
| * Get built-in ETWS primary messages by category. ETWS primary message does not contain text, |
| * so we have to show the pre-built messages to the user. |
| * |
| * @param context Device context |
| * @param category ETWS message category defined in SmsCbConstants |
| * @return ETWS text message in string. Return an empty string if no match. |
| */ |
| private static String getEtwsPrimaryMessage(Context context, int category) { |
| final Resources r = context.getResources(); |
| switch (category) { |
| case ETWS_WARNING_TYPE_EARTHQUAKE: |
| return r.getString(R.string.etws_primary_default_message_earthquake); |
| case ETWS_WARNING_TYPE_TSUNAMI: |
| return r.getString(R.string.etws_primary_default_message_tsunami); |
| case ETWS_WARNING_TYPE_EARTHQUAKE_AND_TSUNAMI: |
| return r.getString(R.string.etws_primary_default_message_earthquake_and_tsunami); |
| case ETWS_WARNING_TYPE_TEST_MESSAGE: |
| return r.getString(R.string.etws_primary_default_message_test); |
| case ETWS_WARNING_TYPE_OTHER_EMERGENCY: |
| return r.getString(R.string.etws_primary_default_message_others); |
| default: |
| return ""; |
| } |
| } |
| |
| /** |
| * Create a new SmsCbMessage object from a header object plus one or more received PDUs. |
| * |
| * @param pdus PDU bytes |
| */ |
| public static SmsCbMessage createSmsCbMessage(Context context, SmsCbHeader header, |
| SmsCbLocation location, byte[][] pdus) |
| throws IllegalArgumentException { |
| long receivedTimeMillis = System.currentTimeMillis(); |
| if (header.isEtwsPrimaryNotification()) { |
| // ETSI TS 23.041 ETWS Primary Notification message |
| // ETWS primary message only contains 4 fields including serial number, |
| // message identifier, warning type, and warning security information. |
| // There is no field for the content/text so we get the text from the resources. |
| return new SmsCbMessage(SmsCbMessage.MESSAGE_FORMAT_3GPP, header.getGeographicalScope(), |
| header.getSerialNumber(), location, header.getServiceCategory(), null, |
| getEtwsPrimaryMessage(context, header.getEtwsInfo().getWarningType()), |
| SmsCbMessage.MESSAGE_PRIORITY_EMERGENCY, header.getEtwsInfo(), |
| header.getCmasInfo(), 0, null /* geometries */, receivedTimeMillis); |
| } else if (header.isUmtsFormat()) { |
| // UMTS format has only 1 PDU |
| byte[] pdu = pdus[0]; |
| Pair<String, String> cbData = parseUmtsBody(header, pdu); |
| String language = cbData.first; |
| String body = cbData.second; |
| int priority = header.isEmergencyMessage() ? SmsCbMessage.MESSAGE_PRIORITY_EMERGENCY |
| : SmsCbMessage.MESSAGE_PRIORITY_NORMAL; |
| int nrPages = pdu[SmsCbHeader.PDU_HEADER_LENGTH]; |
| int wacDataOffset = SmsCbHeader.PDU_HEADER_LENGTH |
| + 1 // number of pages |
| + (PDU_BODY_PAGE_LENGTH + 1) * nrPages; // cb data |
| |
| // Has Warning Area Coordinates information |
| List<Geometry> geometries = null; |
| int maximumWaitingTimeSec = 255; |
| if (pdu.length > wacDataOffset) { |
| try { |
| Pair<Integer, List<Geometry>> wac = parseWarningAreaCoordinates(pdu, |
| wacDataOffset); |
| maximumWaitingTimeSec = wac.first; |
| geometries = wac.second; |
| } catch (Exception ex) { |
| // Catch the exception here, the message will be considered as having no WAC |
| // information which means the message will be broadcasted directly. |
| Slog.e(TAG, "Can't parse warning area coordinates, ex = " + ex.toString()); |
| } |
| } |
| |
| return new SmsCbMessage(SmsCbMessage.MESSAGE_FORMAT_3GPP, |
| header.getGeographicalScope(), header.getSerialNumber(), location, |
| header.getServiceCategory(), language, body, priority, |
| header.getEtwsInfo(), header.getCmasInfo(), maximumWaitingTimeSec, geometries, |
| receivedTimeMillis); |
| } else { |
| String language = null; |
| StringBuilder sb = new StringBuilder(); |
| for (byte[] pdu : pdus) { |
| Pair<String, String> p = parseGsmBody(header, pdu); |
| language = p.first; |
| sb.append(p.second); |
| } |
| int priority = header.isEmergencyMessage() ? SmsCbMessage.MESSAGE_PRIORITY_EMERGENCY |
| : SmsCbMessage.MESSAGE_PRIORITY_NORMAL; |
| |
| return new SmsCbMessage(SmsCbMessage.MESSAGE_FORMAT_3GPP, |
| header.getGeographicalScope(), header.getSerialNumber(), location, |
| header.getServiceCategory(), language, sb.toString(), priority, |
| header.getEtwsInfo(), header.getCmasInfo(), 0, null /* geometries */, |
| receivedTimeMillis); |
| } |
| } |
| |
| /** |
| * Parse WEA Handset Action Message(WHAM) a.k.a geo-fencing trigger message. |
| * |
| * WEA Handset Action Message(WHAM) is a cell broadcast service message broadcast by the network |
| * to direct devices to perform a geo-fencing check on selected alerts. |
| * |
| * WEA Handset Action Message(WHAM) requirements from ATIS-0700041 section 4 |
| * 1. The Warning Message contents of a WHAM shall be in Cell Broadcast(CB) data format as |
| * defined in TS 23.041. |
| * 2. The Warning Message Contents of WHAM shall be limited to one CB page(max 20 referenced |
| * WEA messages). |
| * 3. The broadcast area for a WHAM shall be the union of the broadcast areas of the referenced |
| * WEA message. |
| * @param pdu cell broadcast pdu, including the header |
| * @return {@link GeoFencingTriggerMessage} instance |
| */ |
| public static GeoFencingTriggerMessage createGeoFencingTriggerMessage(byte[] pdu) { |
| try { |
| // Header length + 1(number of page). ATIS-0700041 define the number of page of |
| // geo-fencing trigger message is 1. |
| int whamOffset = SmsCbHeader.PDU_HEADER_LENGTH + 1; |
| |
| BitStreamReader bitReader = new BitStreamReader(pdu, whamOffset); |
| int type = bitReader.read(4); |
| int length = bitReader.read(7); |
| // Skip the remained 5 bits |
| bitReader.skip(); |
| |
| int messageIdentifierCount = (length - 2) * 8 / 32; |
| List<CellBroadcastIdentity> cbIdentifiers = new ArrayList<>(); |
| for (int i = 0; i < messageIdentifierCount; i++) { |
| // Both messageIdentifier and serialNumber are 16 bits integers. |
| // ATIS-0700041 Section 5.1.6 |
| int messageIdentifier = bitReader.read(16); |
| int serialNumber = bitReader.read(16); |
| cbIdentifiers.add(new CellBroadcastIdentity(messageIdentifier, serialNumber)); |
| } |
| return new GeoFencingTriggerMessage(type, cbIdentifiers); |
| } catch (Exception ex) { |
| Slog.e(TAG, "create geo-fencing trigger failed, ex = " + ex.toString()); |
| return null; |
| } |
| } |
| |
| /** |
| * Parse the broadcast area and maximum wait time from the Warning Area Coordinates TLV. |
| * |
| * @param pdu Warning Area Coordinates TLV. |
| * @param wacOffset the offset of Warning Area Coordinates TLV. |
| * @return a pair with the first element is maximum wait time and the second is the broadcast |
| * area. The default value of the maximum wait time is 255 which means use the device default |
| * value. |
| */ |
| private static Pair<Integer, List<Geometry>> parseWarningAreaCoordinates( |
| byte[] pdu, int wacOffset) { |
| // little-endian |
| int wacDataLength = (pdu[wacOffset + 1] << 8) | pdu[wacOffset]; |
| int offset = wacOffset + 2; |
| |
| if (offset + wacDataLength > pdu.length) { |
| throw new IllegalArgumentException("Invalid wac data, expected the length of pdu at" |
| + "least " + offset + wacDataLength + ", actual is " + pdu.length); |
| } |
| |
| BitStreamReader bitReader = new BitStreamReader(pdu, offset); |
| |
| int maximumWaitTimeSec = SmsCbMessage.MAXIMUM_WAIT_TIME_NOT_SET; |
| |
| List<Geometry> geo = new ArrayList<>(); |
| int remainedBytes = wacDataLength; |
| while (remainedBytes > 0) { |
| int type = bitReader.read(4); |
| int length = bitReader.read(10); |
| remainedBytes -= length; |
| // Skip the 2 remained bits |
| bitReader.skip(); |
| |
| switch (type) { |
| case CbGeoUtils.GEO_FENCING_MAXIMUM_WAIT_TIME: |
| maximumWaitTimeSec = bitReader.read(8); |
| break; |
| case CbGeoUtils.GEOMETRY_TYPE_POLYGON: |
| List<LatLng> latLngs = new ArrayList<>(); |
| // Each coordinate is represented by 44 bits integer. |
| // ATIS-0700041 5.2.4 Coordinate coding |
| int n = (length - 2) * 8 / 44; |
| for (int i = 0; i < n; i++) { |
| latLngs.add(getLatLng(bitReader)); |
| } |
| // Skip the padding bits |
| bitReader.skip(); |
| geo.add(new Polygon(latLngs)); |
| break; |
| case CbGeoUtils.GEOMETRY_TYPE_CIRCLE: |
| LatLng center = getLatLng(bitReader); |
| // radius = (wacRadius / 2^6). The unit of wacRadius is km, we use meter as the |
| // distance unit during geo-fencing. |
| // ATIS-0700041 5.2.5 radius coding |
| double radius = (bitReader.read(20) * 1.0 / (1 << 6)) * 1000.0; |
| geo.add(new Circle(center, radius)); |
| break; |
| default: |
| throw new IllegalArgumentException("Unsupported geoType = " + type); |
| } |
| } |
| return new Pair(maximumWaitTimeSec, geo); |
| } |
| |
| /** |
| * The coordinate is (latitude, longitude), represented by a 44 bits integer. |
| * The coding is defined in ATIS-0700041 5.2.4 |
| * @param bitReader |
| * @return coordinate (latitude, longitude) |
| */ |
| private static LatLng getLatLng(BitStreamReader bitReader) { |
| // wacLatitude = floor(((latitude + 90) / 180) * 2^22) |
| // wacLongitude = floor(((longitude + 180) / 360) * 2^22) |
| int wacLat = bitReader.read(22); |
| int wacLng = bitReader.read(22); |
| |
| // latitude = wacLatitude * 180 / 2^22 - 90 |
| // longitude = wacLongitude * 360 / 2^22 -180 |
| return new LatLng((wacLat * 180.0 / (1 << 22)) - 90, (wacLng * 360.0 / (1 << 22) - 180)); |
| } |
| |
| /** |
| * Parse and unpack the UMTS body text according to the encoding in the data coding scheme. |
| * |
| * @param header the message header to use |
| * @param pdu the PDU to decode |
| * @return a pair of string containing the language and body of the message in order |
| */ |
| private static Pair<String, String> parseUmtsBody(SmsCbHeader header, byte[] pdu) { |
| // Payload may contain multiple pages |
| int nrPages = pdu[SmsCbHeader.PDU_HEADER_LENGTH]; |
| String language = header.getDataCodingSchemeStructedData().language; |
| |
| if (pdu.length < SmsCbHeader.PDU_HEADER_LENGTH + 1 + (PDU_BODY_PAGE_LENGTH + 1) |
| * nrPages) { |
| throw new IllegalArgumentException("Pdu length " + pdu.length + " does not match " |
| + nrPages + " pages"); |
| } |
| |
| StringBuilder sb = new StringBuilder(); |
| |
| for (int i = 0; i < nrPages; i++) { |
| // Each page is 82 bytes followed by a length octet indicating |
| // the number of useful octets within those 82 |
| int offset = SmsCbHeader.PDU_HEADER_LENGTH + 1 + (PDU_BODY_PAGE_LENGTH + 1) * i; |
| int length = pdu[offset + PDU_BODY_PAGE_LENGTH]; |
| |
| if (length > PDU_BODY_PAGE_LENGTH) { |
| throw new IllegalArgumentException("Page length " + length |
| + " exceeds maximum value " + PDU_BODY_PAGE_LENGTH); |
| } |
| |
| Pair<String, String> p = unpackBody(pdu, offset, length, |
| header.getDataCodingSchemeStructedData()); |
| language = p.first; |
| sb.append(p.second); |
| } |
| return new Pair(language, sb.toString()); |
| |
| } |
| |
| /** |
| * Parse and unpack the GSM body text according to the encoding in the data coding scheme. |
| * @param header the message header to use |
| * @param pdu the PDU to decode |
| * @return a pair of string containing the language and body of the message in order |
| */ |
| private static Pair<String, String> parseGsmBody(SmsCbHeader header, byte[] pdu) { |
| // Payload is one single page |
| int offset = SmsCbHeader.PDU_HEADER_LENGTH; |
| int length = pdu.length - offset; |
| return unpackBody(pdu, offset, length, header.getDataCodingSchemeStructedData()); |
| } |
| |
| /** |
| * Unpack body text from the pdu using the given encoding, position and length within the pdu. |
| * |
| * @param pdu The pdu |
| * @param offset Position of the first byte to unpack |
| * @param length Number of bytes to unpack |
| * @param dcs data coding scheme |
| * @return a Pair of Strings containing the language and body of the message |
| */ |
| private static Pair<String, String> unpackBody(byte[] pdu, int offset, int length, |
| DataCodingScheme dcs) { |
| String body = null; |
| |
| String language = dcs.language; |
| switch (dcs.encoding) { |
| case SmsConstants.ENCODING_7BIT: |
| body = GsmAlphabet.gsm7BitPackedToString(pdu, offset, length * 8 / 7); |
| |
| if (dcs.hasLanguageIndicator && body != null && body.length() > 2) { |
| // Language is two GSM characters followed by a CR. |
| // The actual body text is offset by 3 characters. |
| language = body.substring(0, 2); |
| body = body.substring(3); |
| } |
| break; |
| |
| case SmsConstants.ENCODING_16BIT: |
| if (dcs.hasLanguageIndicator && pdu.length >= offset + 2) { |
| // Language is two GSM characters. |
| // The actual body text is offset by 2 bytes. |
| language = GsmAlphabet.gsm7BitPackedToString(pdu, offset, 2); |
| offset += 2; |
| length -= 2; |
| } |
| |
| try { |
| body = new String(pdu, offset, (length & 0xfffe), "utf-16"); |
| } catch (UnsupportedEncodingException e) { |
| // Apparently it wasn't valid UTF-16. |
| throw new IllegalArgumentException("Error decoding UTF-16 message", e); |
| } |
| break; |
| |
| default: |
| break; |
| } |
| |
| if (body != null) { |
| // Remove trailing carriage return |
| for (int i = body.length() - 1; i >= 0; i--) { |
| if (body.charAt(i) != CARRIAGE_RETURN) { |
| body = body.substring(0, i + 1); |
| break; |
| } |
| } |
| } else { |
| body = ""; |
| } |
| |
| return new Pair<String, String>(language, body); |
| } |
| |
| /** A class use to facilitate the processing of bits stream data. */ |
| private static final class BitStreamReader { |
| /** The bits stream represent by a bytes array. */ |
| private final byte[] mData; |
| |
| /** The offset of the current byte. */ |
| private int mCurrentOffset; |
| |
| /** |
| * The remained bits of the current byte which have not been read. The most significant |
| * will be read first, so the remained bits are always the least significant bits. |
| */ |
| private int mRemainedBit; |
| |
| /** |
| * Constructor |
| * @param data bit stream data represent by byte array. |
| * @param offset the offset of the first byte. |
| */ |
| BitStreamReader(byte[] data, int offset) { |
| mData = data; |
| mCurrentOffset = offset; |
| mRemainedBit = 8; |
| } |
| |
| /** |
| * Read the first {@code count} bits. |
| * @param count the number of bits need to read |
| * @return {@code bits} represent by an 32-bits integer, therefore {@code count} must be no |
| * greater than 32. |
| */ |
| public int read(int count) throws IndexOutOfBoundsException { |
| int val = 0; |
| while (count > 0) { |
| if (count >= mRemainedBit) { |
| val <<= mRemainedBit; |
| val |= mData[mCurrentOffset] & ((1 << mRemainedBit) - 1); |
| count -= mRemainedBit; |
| mRemainedBit = 8; |
| ++mCurrentOffset; |
| } else { |
| val <<= count; |
| val |= (mData[mCurrentOffset] & ((1 << mRemainedBit) - 1)) |
| >> (mRemainedBit - count); |
| mRemainedBit -= count; |
| count = 0; |
| } |
| } |
| return val; |
| } |
| |
| /** |
| * Skip the current bytes if the remained bits is less than 8. This is useful when |
| * processing the padding or reserved bits. |
| */ |
| public void skip() { |
| if (mRemainedBit < 8) { |
| mRemainedBit = 8; |
| ++mCurrentOffset; |
| } |
| } |
| } |
| |
| static final class GeoFencingTriggerMessage { |
| /** |
| * Indicate the list of active alerts share their warning area coordinates which means the |
| * broadcast area is the union of the broadcast areas of the active alerts in this list. |
| */ |
| public static final int TYPE_ACTIVE_ALERT_SHARE_WAC = 2; |
| |
| public final int type; |
| public final List<CellBroadcastIdentity> cbIdentifiers; |
| |
| GeoFencingTriggerMessage(int type, @NonNull List<CellBroadcastIdentity> cbIdentifiers) { |
| this.type = type; |
| this.cbIdentifiers = cbIdentifiers; |
| } |
| |
| boolean shouldShareBroadcastArea() { |
| return type == TYPE_ACTIVE_ALERT_SHARE_WAC; |
| } |
| |
| static final class CellBroadcastIdentity { |
| public final int messageIdentifier; |
| public final int serialNumber; |
| CellBroadcastIdentity(int messageIdentifier, int serialNumber) { |
| this.messageIdentifier = messageIdentifier; |
| this.serialNumber = serialNumber; |
| } |
| } |
| |
| @Override |
| public String toString() { |
| String identifiers = cbIdentifiers.stream() |
| .map(cbIdentifier ->String.format("(msgId = %d, serial = %d)", |
| cbIdentifier.messageIdentifier, cbIdentifier.serialNumber)) |
| .collect(Collectors.joining(",")); |
| return "triggerType=" + type + " identifiers=" + identifiers; |
| } |
| } |
| } |