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/*
* Copyright (C) 2011 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.nfc.snep;
import android.nfc.FormatException;
import android.nfc.NdefMessage;
import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
public final class SnepMessage {
public static final byte VERSION_MAJOR = (byte) 0x1;
public static final byte VERSION_MINOR = (byte) 0x0;
public static final byte VERSION = (0xF0 & (VERSION_MAJOR << 4)) | (0x0F & VERSION_MINOR);
public static final byte REQUEST_CONTINUE = (byte) 0x00;
public static final byte REQUEST_GET = (byte) 0x01;
public static final byte REQUEST_PUT = (byte) 0x02;
public static final byte REQUEST_REJECT = (byte) 0x07;
public static final byte RESPONSE_CONTINUE = (byte) 0x80;
public static final byte RESPONSE_SUCCESS = (byte) 0x81;
public static final byte RESPONSE_NOT_FOUND = (byte) 0xC0;
public static final byte RESPONSE_EXCESS_DATA = (byte) 0xC1;
public static final byte RESPONSE_BAD_REQUEST = (byte) 0xC2;
public static final byte RESPONSE_NOT_IMPLEMENTED = (byte) 0xE0;
public static final byte RESPONSE_UNSUPPORTED_VERSION = (byte) 0xE1;
public static final byte RESPONSE_REJECT = (byte) 0xFF;
private static final int HEADER_LENGTH = 6;
private final byte mVersion;
private final byte mField;
private final int mLength;
private final int mAcceptableLength;
private final NdefMessage mNdefMessage;
public static SnepMessage getGetRequest(int acceptableLength, NdefMessage ndef) {
return new SnepMessage(VERSION, REQUEST_GET, 4 + ndef.toByteArray().length,
acceptableLength, ndef);
}
public static SnepMessage getPutRequest(NdefMessage ndef) {
return new SnepMessage(VERSION, REQUEST_PUT, ndef.toByteArray().length, 0, ndef);
}
public static SnepMessage getMessage(byte field) {
return new SnepMessage(VERSION, field, 0, 0, null);
}
public static SnepMessage getSuccessResponse(NdefMessage ndef) {
if (ndef == null) {
return new SnepMessage(VERSION, RESPONSE_SUCCESS, 0, 0, null);
} else {
return new SnepMessage(VERSION, RESPONSE_SUCCESS, ndef.toByteArray().length, 0, ndef);
}
}
public static SnepMessage fromByteArray(byte[] data) throws FormatException {
return new SnepMessage(data);
}
private SnepMessage(byte[] data) throws FormatException {
ByteBuffer input = ByteBuffer.wrap(data);
int ndefOffset;
int ndefLength;
mVersion = input.get();
mField = input.get();
mLength = input.getInt();
if (mField == REQUEST_GET) {
mAcceptableLength = input.getInt();
ndefOffset = HEADER_LENGTH + 4;
ndefLength = mLength - 4;
} else {
mAcceptableLength = -1;
ndefOffset = HEADER_LENGTH;
ndefLength = mLength;
}
if (ndefLength > 0) {
byte[] bytes = new byte[ndefLength];
System.arraycopy(data, ndefOffset, bytes, 0, ndefLength);
mNdefMessage = new NdefMessage(bytes);
} else {
mNdefMessage = null;
}
}
SnepMessage(byte version, byte field, int length, int acceptableLength,
NdefMessage ndefMessage) {
mVersion = version;
mField = field;
mLength = length;
mAcceptableLength = acceptableLength;
mNdefMessage = ndefMessage;
}
public byte[] toByteArray() {
byte[] bytes;
if (mNdefMessage != null) {
bytes = mNdefMessage.toByteArray();
} else {
bytes = new byte[0];
}
ByteArrayOutputStream buffer;
try {
if (mField == REQUEST_GET) {
buffer = new ByteArrayOutputStream(bytes.length + HEADER_LENGTH + 4);
} else {
buffer = new ByteArrayOutputStream(bytes.length + HEADER_LENGTH);
}
DataOutputStream output = new DataOutputStream(buffer);
output.writeByte(mVersion);
output.writeByte(mField);
if (mField == REQUEST_GET) {
output.writeInt(bytes.length + 4);
output.writeInt(mAcceptableLength);
} else {
output.writeInt(bytes.length);
}
output.write(bytes);
} catch(IOException e) {
return null;
}
return buffer.toByteArray();
}
public NdefMessage getNdefMessage() {
return mNdefMessage;
}
public byte getField() {
return mField;
}
public byte getVersion() {
return mVersion;
}
public int getLength() {
return mLength;
}
public int getAcceptableLength() {
if (mField != REQUEST_GET) {
throw new UnsupportedOperationException(
"Acceptable Length only available on get request messages.");
}
return mAcceptableLength;
}
}
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