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A LWM2M client and server based on Californium (CoAP) all in one.
/*******************************************************************************
* Copyright (c) 2013-2015 Sierra Wireless and others.
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* and Eclipse Distribution License v1.0 which accompany this distribution.
*
* The Eclipse Public License is available at
* http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.html.
*
* Contributors:
* Sierra Wireless - initial API and implementation
*******************************************************************************/
package org.eclipse.leshan.tlv;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.Date;
import org.eclipse.leshan.util.Charsets;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class TlvEncoder {
private static final Logger LOG = LoggerFactory.getLogger(TlvEncoder.class);
private static final int MAX_LENGTH_8BIT = 256;
private static final int MAX_LENGTH_16BIT = 65_536;
private static final int MAX_LENGTH_24BIT = 16_777_216;
/**
* Encodes an array of TLV.
*/
public static ByteBuffer encode(Tlv[] tlvs) {
int size = 0;
LOG.trace("start");
for (Tlv tlv : tlvs) {
int length = tlvEncodedLength(tlv);
size += tlvEncodedSize(tlv, length);
LOG.trace("tlv size : {}", size);
}
LOG.trace("done, size : {}", size);
ByteBuffer b = ByteBuffer.allocate(size);
b.order(ByteOrder.BIG_ENDIAN);
for (Tlv tlv : tlvs) {
encode(tlv, b);
}
b.flip();
return b;
}
/**
* Encodes an integer value.
*/
public static byte[] encodeInteger(Number number) {
ByteBuffer iBuf = null;
long lValue = number.longValue();
if (lValue >= Byte.MIN_VALUE && lValue <= Byte.MAX_VALUE) {
iBuf = ByteBuffer.allocate(1);
iBuf.put((byte) lValue);
} else if (lValue >= Short.MIN_VALUE && lValue <= Short.MAX_VALUE) {
iBuf = ByteBuffer.allocate(2);
iBuf.putShort((short) lValue);
} else if (lValue >= Integer.MIN_VALUE && lValue <= Integer.MAX_VALUE) {
iBuf = ByteBuffer.allocate(4);
iBuf.putInt((int) lValue);
} else {
iBuf = ByteBuffer.allocate(8);
iBuf.putLong(lValue);
}
return iBuf.array();
}
/**
* Encodes a floating point value.
*/
public static byte[] encodeFloat(Number number) {
ByteBuffer fBuf = null;
if (number instanceof Float) {
fBuf = ByteBuffer.allocate(4);
fBuf.putFloat(number.floatValue());
} else {
fBuf = ByteBuffer.allocate(8);
fBuf.putDouble(number.doubleValue());
}
return fBuf.array();
}
/**
* Encodes a boolean value.
*/
public static byte[] encodeBoolean(boolean value) {
return value ? new byte[] { 1 } : new byte[] { 0 };
}
/**
* Encodes a string value.
*/
public static byte[] encodeString(String value) {
return value.getBytes(Charsets.UTF_8);
}
/**
* Encodes a date value.
*/
public static byte[] encodeDate(Date value) {
ByteBuffer tBuf = ByteBuffer.allocate(4);
tBuf.putInt((int) (value.getTime() / 1000L));
return tBuf.array();
}
private static int tlvEncodedSize(Tlv tlv, int length) {
int size = 1 /* HEADER */;
size += (tlv.getIdentifier() < MAX_LENGTH_8BIT) ? 1 : 2; /* 8 bits or 16 bits identifiers */
if (length < 8) {
size += 0;
} else if (length < MAX_LENGTH_8BIT) {
size += 1;
} else if (length < MAX_LENGTH_16BIT) {
size += 2;
} else if (length < MAX_LENGTH_24BIT) {
size += 3;
} else {
throw new IllegalArgumentException("length should fit in max 24bits");
}
size += length;
return size;
}
private static int tlvEncodedLength(Tlv tlv) {
int length;
switch (tlv.getType()) {
case RESOURCE_VALUE:
case RESOURCE_INSTANCE:
length = tlv.getValue().length;
break;
default:
length = 0;
for (Tlv child : tlv.getChildren()) {
int subLength = tlvEncodedLength(child);
length += tlvEncodedSize(child, subLength);
}
}
return length;
}
private static void encode(Tlv tlv, ByteBuffer b) {
int length;
length = tlvEncodedLength(tlv);
int typeByte;
switch (tlv.getType()) {
case OBJECT_INSTANCE:
typeByte = 0b00_000000;
break;
case RESOURCE_INSTANCE:
typeByte = 0b01_000000;
break;
case MULTIPLE_RESOURCE:
typeByte = 0b10_000000;
break;
case RESOURCE_VALUE:
// encode the value
typeByte = 0b11_000000;
break;
default:
throw new IllegalArgumentException("unknown TLV type : '" + tlv.getType() + "'");
}
// encode identifier length
typeByte |= (tlv.getIdentifier() < MAX_LENGTH_8BIT) ? 0b00_0000 : 0b10_0000;
// type of length
if (length < 8) {
typeByte |= length;
} else if (length < MAX_LENGTH_8BIT) {
typeByte |= 0b0000_1000;
} else if (length < MAX_LENGTH_16BIT) {
typeByte |= 0b0001_0000;
} else {
typeByte |= 0b0001_1000;
}
// fill the buffer
b.put((byte) typeByte);
if (tlv.getIdentifier() < MAX_LENGTH_8BIT) {
b.put((byte) tlv.getIdentifier());
} else {
b.putShort((short) tlv.getIdentifier());
}
// write length
if (length >= 8) {
if (length < MAX_LENGTH_8BIT) {
b.put((byte) length);
} else if (length < MAX_LENGTH_16BIT) {
b.putShort((short) length);
} else {
int msb = (length & 0xFF_00_00) >> 16;
b.put((byte) msb);
b.putShort((short) (length & 0xFF_FF));
typeByte |= 0b0001_1000;
}
}
switch (tlv.getType()) {
case RESOURCE_VALUE:
case RESOURCE_INSTANCE:
b.put(tlv.getValue());
break;
default:
for (Tlv child : tlv.getChildren()) {
encode(child, b);
}
break;
}
}
}