org.ethereum.util.RLP Maven / Gradle / Ivy
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/*
* Copyright (c) [2016] [ ]
* This file is part of the ethereumJ library.
*
* The ethereumJ library is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* The ethereumJ library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with the ethereumJ library. If not, see
* The purpose of RLP is to encode arbitrarily nested arrays of binary data, and
* RLP is the main encoding method used to serialize objects in Ethereum. The
* only purpose of RLP is to encode structure; encoding specific atomic data
* types (eg. strings, integers, floats) is left up to higher-order protocols; in
* Ethereum the standard is that integers are represented in big endian binary
* form. If one wishes to use RLP to encode a dictionary, the two suggested
* canonical forms are to either use [[k1,v1],[k2,v2]...] with keys in
* lexicographic order or to use the higher-level Patricia Tree encoding as
* Ethereum does.
*
* The RLP encoding function takes in an item. An item is defined as follows:
*
* - A string (ie. byte array) is an item - A list of items is an item
*
* For example, an empty string is an item, as is the string containing the word
* "cat", a list containing any number of strings, as well as more complex data
* structures like ["cat",["puppy","cow"],"horse",[[]],"pig",[""],"sheep"]. Note
* that in the context of the rest of this article, "string" will be used as a
* synonym for "a certain number of bytes of binary data"; no special encodings
* are used and no knowledge about the content of the strings is implied.
*
* See: https://github.com/ethereum/wiki/wiki/%5BEnglish%5D-RLP
*
* @author Roman Mandeleil
* @since 01.04.2014
*/
public class RLP {
private static final Logger logger = LoggerFactory.getLogger("rlp");
public static final byte[] EMPTY_ELEMENT_RLP = encodeElement(new byte[0]);
private static final int MAX_DEPTH = 16;
/**
* Allow for content up to size of 2^64 bytes *
*/
private static final double MAX_ITEM_LENGTH = Math.pow(256, 8);
/**
* Reason for threshold according to Vitalik Buterin:
* - 56 bytes maximizes the benefit of both options
* - if we went with 60 then we would have only had 4 slots for long strings
* so RLP would not have been able to store objects above 4gb
* - if we went with 48 then RLP would be fine for 2^128 space, but that's way too much
* - so 56 and 2^64 space seems like the right place to put the cutoff
* - also, that's where Bitcoin's varint does the cutof
*/
private static final int SIZE_THRESHOLD = 56;
/** RLP encoding rules are defined as follows: */
/*
* For a single byte whose value is in the [0x00, 0x7f] range, that byte is
* its own RLP encoding.
*/
/**
* [0x80]
* If a string is 0-55 bytes long, the RLP encoding consists of a single
* byte with value 0x80 plus the length of the string followed by the
* string. The range of the first byte is thus [0x80, 0xb7].
*/
private static final int OFFSET_SHORT_ITEM = 0x80;
/**
* [0xb7]
* If a string is more than 55 bytes long, the RLP encoding consists of a
* single byte with value 0xb7 plus the length of the length of the string
* in binary form, followed by the length of the string, followed by the
* string. For example, a length-1024 string would be encoded as
* \xb9\x04\x00 followed by the string. The range of the first byte is thus
* [0xb8, 0xbf].
*/
private static final int OFFSET_LONG_ITEM = 0xb7;
/**
* [0xc0]
* If the total payload of a list (i.e. the combined length of all its
* items) is 0-55 bytes long, the RLP encoding consists of a single byte
* with value 0xc0 plus the length of the list followed by the concatenation
* of the RLP encodings of the items. The range of the first byte is thus
* [0xc0, 0xf7].
*/
private static final int OFFSET_SHORT_LIST = 0xc0;
/**
* [0xf7]
* If the total payload of a list is more than 55 bytes long, the RLP
* encoding consists of a single byte with value 0xf7 plus the length of the
* length of the list in binary form, followed by the length of the list,
* followed by the concatenation of the RLP encodings of the items. The
* range of the first byte is thus [0xf8, 0xff].
*/
private static final int OFFSET_LONG_LIST = 0xf7;
/* ******************************************************
* DECODING *
* ******************************************************/
private static byte decodeOneByteItem(byte[] data, int index) {
// null item
if ((data[index] & 0xFF) == OFFSET_SHORT_ITEM) {
return (byte) (data[index] - OFFSET_SHORT_ITEM);
}
// single byte item
if ((data[index] & 0xFF) < OFFSET_SHORT_ITEM) {
return data[index];
}
// single byte item
if ((data[index] & 0xFF) == OFFSET_SHORT_ITEM + 1) {
return data[index + 1];
}
return 0;
}
public static int decodeInt(byte[] data, int index) {
int value = 0;
// NOTE: From RLP doc:
// Ethereum integers must be represented in big endian binary form
// with no leading zeroes (thus making the integer value zero be
// equivalent to the empty byte array)
if (data[index] == 0x00) {
throw new RuntimeException("not a number");
} else if ((data[index] & 0xFF) < OFFSET_SHORT_ITEM) {
return data[index];
} else if ((data[index] & 0xFF) <= OFFSET_SHORT_ITEM + Integer.BYTES) {
byte length = (byte) (data[index] - OFFSET_SHORT_ITEM);
byte pow = (byte) (length - 1);
for (int i = 1; i <= length; ++i) {
// << (8 * pow) == bit shift to 0 (*1), 8 (*256) , 16 (*65..)..
value += (data[index + i] & 0xFF) << (8 * pow);
pow--;
}
} else {
// If there are more than 4 bytes, it is not going
// to decode properly into an int.
throw new RuntimeException("wrong decode attempt");
}
return value;
}
static short decodeShort(byte[] data, int index) {
short value = 0;
if (data[index] == 0x00) {
throw new RuntimeException("not a number");
} else if ((data[index] & 0xFF) < OFFSET_SHORT_ITEM) {
return data[index];
} else if ((data[index] & 0xFF) <= OFFSET_SHORT_ITEM + Short.BYTES) {
byte length = (byte) (data[index] - OFFSET_SHORT_ITEM);
byte pow = (byte) (length - 1);
for (int i = 1; i <= length; ++i) {
// << (8 * pow) == bit shift to 0 (*1), 8 (*256) , 16 (*65..)
value += (data[index + i] & 0xFF) << (8 * pow);
pow--;
}
} else {
// If there are more than 2 bytes, it is not going
// to decode properly into a short.
throw new RuntimeException("wrong decode attempt");
}
return value;
}
public static long decodeLong(byte[] data, int index) {
long value = 0;
if (data[index] == 0x00) {
throw new RuntimeException("not a number");
} else if ((data[index] & 0xFF) < OFFSET_SHORT_ITEM) {
return data[index];
} else if ((data[index] & 0xFF) <= OFFSET_SHORT_ITEM + Long.BYTES) {
byte length = (byte) (data[index] - OFFSET_SHORT_ITEM);
byte pow = (byte) (length - 1);
for (int i = 1; i <= length; ++i) {
// << (8 * pow) == bit shift to 0 (*1), 8 (*256) , 16 (*65..)..
value += (long) (data[index + i] & 0xFF) << (8 * pow);
pow--;
}
} else {
// If there are more than 8 bytes, it is not going
// to decode properly into a long.
throw new RuntimeException("wrong decode attempt");
}
return value;
}
private static String decodeStringItem(byte[] data, int index) {
final byte[] valueBytes = decodeItemBytes(data, index);
if (valueBytes.length == 0) {
// shortcut
return "";
} else {
return new String(valueBytes);
}
}
public static BigInteger decodeBigInteger(byte[] data, int index) {
final byte[] valueBytes = decodeItemBytes(data, index);
if (valueBytes.length == 0) {
// shortcut
return BigInteger.ZERO;
} else {
BigInteger res = new BigInteger(1, valueBytes);
return res;
}
}
private static byte[] decodeByteArray(byte[] data, int index) {
return decodeItemBytes(data, index);
}
private static int nextItemLength(byte[] data, int index) {
if (index >= data.length)
return -1;
// [0xf8, 0xff]
if ((data[index] & 0xFF) > OFFSET_LONG_LIST) {
byte lengthOfLength = (byte) (data[index] - OFFSET_LONG_LIST);
return calcLength(lengthOfLength, data, index);
}
// [0xc0, 0xf7]
if ((data[index] & 0xFF) >= OFFSET_SHORT_LIST
&& (data[index] & 0xFF) <= OFFSET_LONG_LIST) {
return (byte) ((data[index] & 0xFF) - OFFSET_SHORT_LIST);
}
// [0xb8, 0xbf]
if ((data[index] & 0xFF) > OFFSET_LONG_ITEM
&& (data[index] & 0xFF) < OFFSET_SHORT_LIST) {
byte lengthOfLength = (byte) (data[index] - OFFSET_LONG_ITEM);
return calcLength(lengthOfLength, data, index);
}
// [0x81, 0xb7]
if ((data[index] & 0xFF) > OFFSET_SHORT_ITEM
&& (data[index] & 0xFF) <= OFFSET_LONG_ITEM) {
return (byte) ((data[index] & 0xFF) - OFFSET_SHORT_ITEM);
}
// [0x00, 0x80]
if ((data[index] & 0xFF) <= OFFSET_SHORT_ITEM) {
return 1;
}
return -1;
}
public static byte[] decodeIP4Bytes(byte[] data, int index) {
int offset = 1;
final byte[] result = new byte[4];
for (int i = 0; i < 4; i++) {
result[i] = decodeOneByteItem(data, index + offset);
if ((data[index + offset] & 0xFF) > OFFSET_SHORT_ITEM)
offset += 2;
else
offset += 1;
}
// return IP address
return result;
}
public static int getFirstListElement(byte[] payload, int pos) {
if (pos >= payload.length)
return -1;
// [0xf8, 0xff]
if ((payload[pos] & 0xFF) > OFFSET_LONG_LIST) {
byte lengthOfLength = (byte) (payload[pos] - OFFSET_LONG_LIST);
return pos + lengthOfLength + 1;
}
// [0xc0, 0xf7]
if ((payload[pos] & 0xFF) >= OFFSET_SHORT_LIST
&& (payload[pos] & 0xFF) <= OFFSET_LONG_LIST) {
return pos + 1;
}
// [0xb8, 0xbf]
if ((payload[pos] & 0xFF) > OFFSET_LONG_ITEM
&& (payload[pos] & 0xFF) < OFFSET_SHORT_LIST) {
byte lengthOfLength = (byte) (payload[pos] - OFFSET_LONG_ITEM);
return pos + lengthOfLength + 1;
}
return -1;
}
public static int getNextElementIndex(byte[] payload, int pos) {
if (pos >= payload.length)
return -1;
// [0xf8, 0xff]
if ((payload[pos] & 0xFF) > OFFSET_LONG_LIST) {
byte lengthOfLength = (byte) (payload[pos] - OFFSET_LONG_LIST);
int length = calcLength(lengthOfLength, payload, pos);
return pos + lengthOfLength + length + 1;
}
// [0xc0, 0xf7]
if ((payload[pos] & 0xFF) >= OFFSET_SHORT_LIST
&& (payload[pos] & 0xFF) <= OFFSET_LONG_LIST) {
byte length = (byte) ((payload[pos] & 0xFF) - OFFSET_SHORT_LIST);
return pos + 1 + length;
}
// [0xb8, 0xbf]
if ((payload[pos] & 0xFF) > OFFSET_LONG_ITEM
&& (payload[pos] & 0xFF) < OFFSET_SHORT_LIST) {
byte lengthOfLength = (byte) (payload[pos] - OFFSET_LONG_ITEM);
int length = calcLength(lengthOfLength, payload, pos);
return pos + lengthOfLength + length + 1;
}
// [0x81, 0xb7]
if ((payload[pos] & 0xFF) > OFFSET_SHORT_ITEM
&& (payload[pos] & 0xFF) <= OFFSET_LONG_ITEM) {
byte length = (byte) ((payload[pos] & 0xFF) - OFFSET_SHORT_ITEM);
return pos + 1 + length;
}
// []0x80]
if ((payload[pos] & 0xFF) == OFFSET_SHORT_ITEM) {
return pos + 1;
}
// [0x00, 0x7f]
if ((payload[pos] & 0xFF) < OFFSET_SHORT_ITEM) {
return pos + 1;
}
return -1;
}
/**
* Parse length of long item or list.
* RLP supports lengths with up to 8 bytes long,
* but due to java limitation it returns either encoded length
* or {@link Integer#MAX_VALUE} in case if encoded length is greater
*
* @param lengthOfLength length of length in bytes
* @param msgData message
* @param pos position to parse from
*
* @return calculated length
*/
private static int calcLength(int lengthOfLength, byte[] msgData, int pos) {
byte pow = (byte) (lengthOfLength - 1);
int length = 0;
for (int i = 1; i <= lengthOfLength; ++i) {
int bt = msgData[pos + i] & 0xFF;
int shift = 8 * pow;
// no leading zeros are acceptable
if (bt == 0 && length == 0) {
throw new RuntimeException("RLP length contains leading zeros");
}
// return MAX_VALUE if index of highest bit is more than 31
if (32 - Integer.numberOfLeadingZeros(bt) + shift > 31) {
return Integer.MAX_VALUE;
}
length += bt << shift;
pow--;
}
// check that length is in payload bounds
verifyLength(length, msgData.length - pos - lengthOfLength);
return length;
}
public static byte getCommandCode(byte[] data) {
int index = getFirstListElement(data, 0);
final byte command = data[index];
return ((command & 0xFF) == OFFSET_SHORT_ITEM) ? 0 : command;
}
/**
* Parse wire byte[] message into RLP elements
*
* @param msgData - raw RLP data
* @param depthLimit - limits depth of decoding
* @return rlpList
* - outcome of recursive RLP structure
*/
public static RLPList decode2(byte[] msgData, int depthLimit) {
if (depthLimit < 1) {
throw new RuntimeException("Depth limit should be 1 or higher");
}
RLPList rlpList = new RLPList();
fullTraverse(msgData, 0, 0, msgData.length, rlpList, depthLimit);
return rlpList;
}
/**
* Parse wire byte[] message into RLP elements
*
* @param msgData - raw RLP data
* @return rlpList
* - outcome of recursive RLP structure
*/
public static RLPList decode2(byte[] msgData) {
RLPList rlpList = new RLPList();
fullTraverse(msgData, 0, 0, msgData.length, rlpList, Integer.MAX_VALUE);
return rlpList;
}
/**
* Decodes RLP with list without going deep after 1st level list
* (actually, 2nd as 1st level is wrap only)
*
* So assuming you've packed several byte[] with {@link #encodeList(byte[]...)},
* you could use this method to unpack them,
* getting RLPList with RLPItem's holding byte[] inside
* @param msgData rlp data
* @return list of RLPItems
*/
public static RLPList unwrapList(byte[] msgData) {
return (RLPList) decode2(msgData, 2).get(0);
}
public static RLPElement decode2OneItem(byte[] msgData, int startPos) {
RLPList rlpList = new RLPList();
fullTraverse(msgData, 0, startPos, startPos + 1, rlpList, Integer.MAX_VALUE);
return rlpList.get(0);
}
/**
* Get exactly one message payload
*/
static void fullTraverse(byte[] msgData, int level, int startPos,
int endPos, RLPList rlpList, int depth) {
if (level > MAX_DEPTH) {
throw new RuntimeException(String.format("Error: Traversing over max RLP depth (%s)", MAX_DEPTH));
}
try {
if (msgData == null || msgData.length == 0)
return;
int pos = startPos;
while (pos < endPos) {
logger.debug("fullTraverse: level: " + level + " startPos: " + pos + " endPos: " + endPos);
// It's a list with a payload more than 55 bytes
// data[0] - 0xF7 = how many next bytes allocated
// for the length of the list
if ((msgData[pos] & 0xFF) > OFFSET_LONG_LIST) {
byte lengthOfLength = (byte) (msgData[pos] - OFFSET_LONG_LIST);
int length = calcLength(lengthOfLength, msgData, pos);
if (length < SIZE_THRESHOLD) {
throw new RuntimeException("Short list has been encoded as long list");
}
// check that length is in payload bounds
verifyLength(length, msgData.length - pos - lengthOfLength);
byte[] rlpData = new byte[lengthOfLength + length + 1];
System.arraycopy(msgData, pos, rlpData, 0, lengthOfLength
+ length + 1);
if(level + 1 < depth) {
RLPList newLevelList = new RLPList();
newLevelList.setRLPData(rlpData);
fullTraverse(msgData, level + 1, pos + lengthOfLength + 1,
pos + lengthOfLength + length + 1, newLevelList, depth);
rlpList.add(newLevelList);
} else {
rlpList.add(new RLPItem(rlpData));
}
pos += lengthOfLength + length + 1;
continue;
}
// It's a list with a payload less than 55 bytes
if ((msgData[pos] & 0xFF) >= OFFSET_SHORT_LIST
&& (msgData[pos] & 0xFF) <= OFFSET_LONG_LIST) {
byte length = (byte) ((msgData[pos] & 0xFF) - OFFSET_SHORT_LIST);
byte[] rlpData = new byte[length + 1];
System.arraycopy(msgData, pos, rlpData, 0, length + 1);
if(level + 1 < depth) {
RLPList newLevelList = new RLPList();
newLevelList.setRLPData(rlpData);
if (length > 0)
fullTraverse(msgData, level + 1, pos + 1, pos + length + 1, newLevelList, depth);
rlpList.add(newLevelList);
} else {
rlpList.add(new RLPItem(rlpData));
}
pos += 1 + length;
continue;
}
// It's an item with a payload more than 55 bytes
// data[0] - 0xB7 = how much next bytes allocated for
// the length of the string
if ((msgData[pos] & 0xFF) > OFFSET_LONG_ITEM
&& (msgData[pos] & 0xFF) < OFFSET_SHORT_LIST) {
byte lengthOfLength = (byte) (msgData[pos] - OFFSET_LONG_ITEM);
int length = calcLength(lengthOfLength, msgData, pos);
if (length < SIZE_THRESHOLD) {
throw new RuntimeException("Short item has been encoded as long item");
}
// check that length is in payload bounds
verifyLength(length, msgData.length - pos - lengthOfLength);
// now we can parse an item for data[1]..data[length]
byte[] item = new byte[length];
System.arraycopy(msgData, pos + lengthOfLength + 1, item,
0, length);
RLPItem rlpItem = new RLPItem(item);
rlpList.add(rlpItem);
pos += lengthOfLength + length + 1;
continue;
}
// It's an item less than 55 bytes long,
// data[0] - 0x80 == length of the item
if ((msgData[pos] & 0xFF) > OFFSET_SHORT_ITEM
&& (msgData[pos] & 0xFF) <= OFFSET_LONG_ITEM) {
byte length = (byte) ((msgData[pos] & 0xFF) - OFFSET_SHORT_ITEM);
byte[] item = new byte[length];
System.arraycopy(msgData, pos + 1, item, 0, length);
if (length == 1 && (item[0] & 0xFF) < OFFSET_SHORT_ITEM) {
throw new RuntimeException("Single byte has been encoded as byte string");
}
RLPItem rlpItem = new RLPItem(item);
rlpList.add(rlpItem);
pos += 1 + length;
continue;
}
// null item
if ((msgData[pos] & 0xFF) == OFFSET_SHORT_ITEM) {
byte[] item = ByteUtil.EMPTY_BYTE_ARRAY;
RLPItem rlpItem = new RLPItem(item);
rlpList.add(rlpItem);
pos += 1;
continue;
}
// single byte item
if ((msgData[pos] & 0xFF) < OFFSET_SHORT_ITEM) {
byte[] item = {(byte) (msgData[pos] & 0xFF)};
RLPItem rlpItem = new RLPItem(item);
rlpList.add(rlpItem);
pos += 1;
}
}
} catch (Exception e) {
throw new RuntimeException("RLP wrong encoding (" + Hex.toHexString(msgData, startPos, endPos - startPos) + ")", e);
} catch (OutOfMemoryError e) {
throw new RuntimeException("Invalid RLP (excessive mem allocation while parsing) (" + Hex.toHexString(msgData, startPos, endPos - startPos) + ")", e);
}
}
/**
* Compares supplied length information with maximum possible
* @param suppliedLength Length info from header
* @param availableLength Length of remaining object
* @throws RuntimeException if supplied length is bigger than available
*/
private static void verifyLength(int suppliedLength, int availableLength) {
if (suppliedLength > availableLength) {
throw new RuntimeException(String.format("Length parsed from RLP (%s bytes) is greater " +
"than possible size of data (%s bytes)", suppliedLength, availableLength));
}
}
/**
* Reads any RLP encoded byte-array and returns all objects as byte-array or list of byte-arrays
*
* @param data RLP encoded byte-array
* @param pos position in the array to start reading
* @return DecodeResult encapsulates the decoded items as a single Object and the final read position
*/
public static DecodeResult decode(byte[] data, int pos) {
if (data == null || data.length < 1) {
return null;
}
int prefix = data[pos] & 0xFF;
if (prefix == OFFSET_SHORT_ITEM) { // 0x80
return new DecodeResult(pos + 1, ""); // means no length or 0
} else if (prefix < OFFSET_SHORT_ITEM) { // [0x00, 0x7f]
return new DecodeResult(pos + 1, new byte[]{data[pos]}); // byte is its own RLP encoding
} else if (prefix <= OFFSET_LONG_ITEM) { // [0x81, 0xb7]
int len = prefix - OFFSET_SHORT_ITEM; // length of the encoded bytes
return new DecodeResult(pos + 1 + len, copyOfRange(data, pos + 1, pos + 1 + len));
} else if (prefix < OFFSET_SHORT_LIST) { // [0xb8, 0xbf]
int lenlen = prefix - OFFSET_LONG_ITEM; // length of length the encoded bytes
int lenbytes = byteArrayToInt(copyOfRange(data, pos + 1, pos + 1 + lenlen)); // length of encoded bytes
// check that length is in payload bounds
verifyLength(lenbytes, data.length - pos - 1 - lenlen);
return new DecodeResult(pos + 1 + lenlen + lenbytes, copyOfRange(data, pos + 1 + lenlen, pos + 1 + lenlen
+ lenbytes));
} else if (prefix <= OFFSET_LONG_LIST) { // [0xc0, 0xf7]
int len = prefix - OFFSET_SHORT_LIST; // length of the encoded list
int prevPos = pos;
pos++;
return decodeList(data, pos, prevPos, len);
} else if (prefix <= 0xFF) { // [0xf8, 0xff]
int lenlen = prefix - OFFSET_LONG_LIST; // length of length the encoded list
int lenlist = byteArrayToInt(copyOfRange(data, pos + 1, pos + 1 + lenlen)); // length of encoded bytes
pos = pos + lenlen + 1; // start at position of first element in list
int prevPos = lenlist;
return decodeList(data, pos, prevPos, lenlist);
} else {
throw new RuntimeException("Only byte values between 0x00 and 0xFF are supported, but got: " + prefix);
}
}
public static final class LList {
private final byte[] rlp;
private final int[] offsets = new int[32];
private final int[] lens = new int[32];
private int cnt;
public LList(byte[] rlp) {
this.rlp = rlp;
}
public byte[] getEncoded() {
byte encoded[][] = new byte[cnt][];
for (int i = 0; i < cnt; i++) {
encoded[i] = encodeElement(getBytes(i));
}
return encodeList(encoded);
}
public void add(int off, int len, boolean isList) {
offsets[cnt] = off;
lens[cnt] = isList ? (-1 - len) : len;
cnt++;
}
public byte[] getBytes(int idx) {
int len = lens[idx];
len = len < 0 ? (-len - 1) : len;
byte[] ret = new byte[len];
System.arraycopy(rlp, offsets[idx], ret, 0, len);
return ret;
}
public LList getList(int idx) {
return decodeLazyList(rlp, offsets[idx], -lens[idx] - 1);
}
public boolean isList(int idx) {
return lens[idx] < 0;
}
public int size() {
return cnt;
}
}
public static LList decodeLazyList(byte[] data) {
return decodeLazyList(data, 0, data.length).getList(0);
}
public static LList decodeLazyList(byte[] data, int pos, int length) {
if (data == null || data.length < 1) {
return null;
}
LList ret = new LList(data);
int end = pos + length;
while(pos < end) {
int prefix = data[pos] & 0xFF;
if (prefix == OFFSET_SHORT_ITEM) { // 0x80
ret.add(pos, 0, false); // means no length or 0
pos++;
} else if (prefix < OFFSET_SHORT_ITEM) { // [0x00, 0x7f]
ret.add(pos, 1, false); // means no length or 0
pos++;
} else if (prefix <= OFFSET_LONG_ITEM) { // [0x81, 0xb7]
int len = prefix - OFFSET_SHORT_ITEM; // length of the encoded bytes
ret.add(pos + 1, len, false);
pos += len + 1;
} else if (prefix < OFFSET_SHORT_LIST) { // [0xb8, 0xbf]
int lenlen = prefix - OFFSET_LONG_ITEM; // length of length the encoded bytes
int lenbytes = byteArrayToInt(copyOfRange(data, pos + 1, pos + 1 + lenlen)); // length of encoded bytes
// check that length is in payload bounds
verifyLength(lenbytes, data.length - pos - 1 - lenlen);
ret.add(pos + 1 + lenlen, lenbytes, false);
pos += 1 + lenlen + lenbytes;
} else if (prefix <= OFFSET_LONG_LIST) { // [0xc0, 0xf7]
int len = prefix - OFFSET_SHORT_LIST; // length of the encoded list
ret.add(pos + 1, len, true);
pos += 1 + len;
} else if (prefix <= 0xFF) { // [0xf8, 0xff]
int lenlen = prefix - OFFSET_LONG_LIST; // length of length the encoded list
int lenlist = byteArrayToInt(copyOfRange(data, pos + 1, pos + 1 + lenlen)); // length of encoded bytes
// check that length is in payload bounds
verifyLength(lenlist, data.length - pos - 1 - lenlen);
ret.add(pos + 1 + lenlen, lenlist, true);
pos += 1 + lenlen + lenlist; // start at position of first element in list
} else {
throw new RuntimeException("Only byte values between 0x00 and 0xFF are supported, but got: " + prefix);
}
}
return ret;
}
private static DecodeResult decodeList(byte[] data, int pos, int prevPos, int len) {
// check that length is in payload bounds
verifyLength(len, data.length - pos);
List