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GsmSmsCbMessage.javaAPI DocAndroid 5.1 API11201Thu Mar 12 22:22:54 GMT 2015com.android.internal.telephony.gsm

GsmSmsCbMessage

public class GsmSmsCbMessage extends Object
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.

Fields Summary
private static final String[]
LANGUAGE_CODES_GROUP_0
Languages in the 0000xxxx DCS group as defined in 3GPP TS 23.038, section 5.
private static final String[]
LANGUAGE_CODES_GROUP_2
Languages in the 0010xxxx DCS group as defined in 3GPP TS 23.038, section 5.
private static final char
CARRIAGE_RETURN
private static final int
PDU_BODY_PAGE_LENGTH
Constructors Summary
private GsmSmsCbMessage()
Utility class with only static methods.
Methods Summary
static android.telephony.SmsCbMessagecreateSmsCbMessage(SmsCbHeader header, android.telephony.SmsCbLocation location, byte[][] pdus)
Create a new SmsCbMessage object from a header object plus one or more received PDUs.

param
pdus PDU bytes

        if (header.isEtwsPrimaryNotification()) {
            return new SmsCbMessage(SmsCbMessage.MESSAGE_FORMAT_3GPP,
                    header.getGeographicalScope(), header.getSerialNumber(),
                    location, header.getServiceCategory(),
                    null, "ETWS", SmsCbMessage.MESSAGE_PRIORITY_EMERGENCY,
                    header.getEtwsInfo(), header.getCmasInfo());
        } else {
            String language = null;
            StringBuilder sb = new StringBuilder();
            for (byte[] pdu : pdus) {
                Pair<String, String> p = parseBody(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());
        }
public static android.telephony.SmsCbMessagecreateSmsCbMessage(android.telephony.SmsCbLocation location, byte[][] pdus)
Create a new SmsCbMessage object from one or more received PDUs. This is used by some CellBroadcastReceiver test cases, because SmsCbHeader is now package local.

param
location the location (geographical scope) for the message
param
pdus PDU bytes

        SmsCbHeader header = new SmsCbHeader(pdus[0]);
        return createSmsCbMessage(header, location, pdus);
private static android.util.PairparseBody(SmsCbHeader header, byte[] pdu)
Parse and unpack the body text according to the encoding in the DCS. After completing successfully this method will have assigned the body text into mBody, and optionally the language code into mLanguage

param
header the message header to use
param
pdu the PDU to decode
return
a Pair of Strings containing the language and body of the message

        int encoding;
        String language = null;
        boolean hasLanguageIndicator = false;
        int dataCodingScheme = header.getDataCodingScheme();

        // Extract encoding and language from DCS, as defined in 3gpp TS 23.038,
        // section 5.
        switch ((dataCodingScheme & 0xf0) >> 4) {
            case 0x00:
                encoding = SmsConstants.ENCODING_7BIT;
                language = LANGUAGE_CODES_GROUP_0[dataCodingScheme & 0x0f];
                break;

            case 0x01:
                hasLanguageIndicator = true;
                if ((dataCodingScheme & 0x0f) == 0x01) {
                    encoding = SmsConstants.ENCODING_16BIT;
                } else {
                    encoding = SmsConstants.ENCODING_7BIT;
                }
                break;

            case 0x02:
                encoding = SmsConstants.ENCODING_7BIT;
                language = LANGUAGE_CODES_GROUP_2[dataCodingScheme & 0x0f];
                break;

            case 0x03:
                encoding = SmsConstants.ENCODING_7BIT;
                break;

            case 0x04:
            case 0x05:
                switch ((dataCodingScheme & 0x0c) >> 2) {
                    case 0x01:
                        encoding = SmsConstants.ENCODING_8BIT;
                        break;

                    case 0x02:
                        encoding = SmsConstants.ENCODING_16BIT;
                        break;

                    case 0x00:
                    default:
                        encoding = SmsConstants.ENCODING_7BIT;
                        break;
                }
                break;

            case 0x06:
            case 0x07:
                // Compression not supported
            case 0x09:
                // UDH structure not supported
            case 0x0e:
                // Defined by the WAP forum not supported
                throw new IllegalArgumentException("Unsupported GSM dataCodingScheme "
                        + dataCodingScheme);

            case 0x0f:
                if (((dataCodingScheme & 0x04) >> 2) == 0x01) {
                    encoding = SmsConstants.ENCODING_8BIT;
                } else {
                    encoding = SmsConstants.ENCODING_7BIT;
                }
                break;

            default:
                // Reserved values are to be treated as 7-bit
                encoding = SmsConstants.ENCODING_7BIT;
                break;
        }

        if (header.isUmtsFormat()) {
            // Payload may contain multiple pages
            int nrPages = pdu[SmsCbHeader.PDU_HEADER_LENGTH];

            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, encoding, offset, length,
                        hasLanguageIndicator, language);
                language = p.first;
                sb.append(p.second);
            }
            return new Pair<String, String>(language, sb.toString());
        } else {
            // Payload is one single page
            int offset = SmsCbHeader.PDU_HEADER_LENGTH;
            int length = pdu.length - offset;

            return unpackBody(pdu, encoding, offset, length, hasLanguageIndicator, language);
        }
private static android.util.PairunpackBody(byte[] pdu, int encoding, int offset, int length, boolean hasLanguageIndicator, java.lang.String language)
Unpack body text from the pdu using the given encoding, position and length within the pdu

param
pdu The pdu
param
encoding The encoding, as derived from the DCS
param
offset Position of the first byte to unpack
param
length Number of bytes to unpack
param
hasLanguageIndicator true if the body text is preceded by a language indicator. If so, this method will as a side-effect assign the extracted language code into mLanguage
param
language the language to return if hasLanguageIndicator is false
return
a Pair of Strings containing the language and body of the message

        String body = null;

        switch (encoding) {
            case SmsConstants.ENCODING_7BIT:
                body = GsmAlphabet.gsm7BitPackedToString(pdu, offset, length * 8 / 7);

                if (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 (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);