mirror of
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109 lines
4.0 KiB
Java
109 lines
4.0 KiB
Java
/**
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* Copyright (C) 2011 Whisper Systems
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* Copyright (C) 2014 Open Whisper Systems
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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package org.thoughtcrime.securesms.sms;
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import android.util.Log;
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import org.thoughtcrime.securesms.protocol.WirePrefix;
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import org.thoughtcrime.securesms.util.Base64;
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import org.whispersystems.libaxolotl.protocol.CiphertextMessage;
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import java.io.IOException;
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public class SmsTransportDetails {
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public static final int SMS_SIZE = 160;
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public static final int MULTIPART_SMS_SIZE = 153;
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public static final int BASE_MAX_BYTES = Base64.getEncodedBytesForTarget(SMS_SIZE - WirePrefix.PREFIX_SIZE);
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public static final int SINGLE_MESSAGE_MAX_BYTES = BASE_MAX_BYTES - MultipartSmsTransportMessage.SINGLE_MESSAGE_MULTIPART_OVERHEAD;
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public static final int MULTI_MESSAGE_MAX_BYTES = BASE_MAX_BYTES - MultipartSmsTransportMessage.MULTI_MESSAGE_MULTIPART_OVERHEAD;
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public static final int FIRST_MULTI_MESSAGE_MAX_BYTES = BASE_MAX_BYTES - MultipartSmsTransportMessage.FIRST_MULTI_MESSAGE_MULTIPART_OVERHEAD;
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public static final int ENCRYPTED_SINGLE_MESSAGE_BODY_MAX_SIZE = SINGLE_MESSAGE_MAX_BYTES - CiphertextMessage.ENCRYPTED_MESSAGE_OVERHEAD;
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public byte[] getEncodedMessage(byte[] messageWithMac) {
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String encodedMessage = Base64.encodeBytesWithoutPadding(messageWithMac);
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Log.w("SmsTransportDetails", "Encoded Message Length: " + encodedMessage.length());
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return encodedMessage.getBytes();
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}
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public byte[] getDecodedMessage(byte[] encodedMessageBytes) throws IOException {
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String encodedMessage = new String(encodedMessageBytes);
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return Base64.decodeWithoutPadding(encodedMessage);
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}
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public byte[] getStrippedPaddingMessageBody(byte[] messageWithPadding) {
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int paddingBeginsIndex = 0;
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for (int i=1;i<messageWithPadding.length;i++) {
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if (messageWithPadding[i] == (byte)0x00) {
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paddingBeginsIndex = i;
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break;
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}
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}
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if (paddingBeginsIndex == 0)
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return messageWithPadding;
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byte[] message = new byte[paddingBeginsIndex];
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System.arraycopy(messageWithPadding, 0, message, 0, message.length);
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return message;
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}
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public byte[] getPaddedMessageBody(byte[] messageBody) {
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int paddedBodySize = getMaxBodySizeForBytes(messageBody.length);
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Log.w("SmsTransportDetails", "Padding message body out to: " + paddedBodySize);
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byte[] paddedBody = new byte[paddedBodySize];
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System.arraycopy(messageBody, 0, paddedBody, 0, messageBody.length);
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return paddedBody;
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}
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private int getMaxBodySizeForBytes(int bodyLength) {
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int encryptedBodyLength = bodyLength + CiphertextMessage.ENCRYPTED_MESSAGE_OVERHEAD;
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int messageRecordsForBody = getMessageCountForBytes(encryptedBodyLength);
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if (messageRecordsForBody == 1) {
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return ENCRYPTED_SINGLE_MESSAGE_BODY_MAX_SIZE;
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} else {
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return
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FIRST_MULTI_MESSAGE_MAX_BYTES +
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(MULTI_MESSAGE_MAX_BYTES * (messageRecordsForBody-1)) -
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CiphertextMessage.ENCRYPTED_MESSAGE_OVERHEAD;
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}
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}
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public int getMessageCountForBytes(int bytes) {
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if (bytes <= SINGLE_MESSAGE_MAX_BYTES)
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return 1;
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bytes = Math.max(bytes - FIRST_MULTI_MESSAGE_MAX_BYTES, 0);
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int messageCount = 1 + (bytes / MULTI_MESSAGE_MAX_BYTES);
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int remainder = bytes % MULTI_MESSAGE_MAX_BYTES;
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if (remainder > 0)
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messageCount++;
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return messageCount;
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}
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}
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