EncodingUtils.java
/*
* Copyright 2013-2021 the original author or authors.
*
* 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
*
* https://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 org.springframework.cloud.sleuth.internal;
import java.util.Arrays;
import org.springframework.util.Assert;
/**
* Adopted from OpenTelemetry API.
*
* @since 3.1.0
*/
public final class EncodingUtils {
private static final ThreadLocal<char[]> charBuffer = new ThreadLocal();
private EncodingUtils() {
}
static final int LONG_BYTES = Long.SIZE / Byte.SIZE;
static final int BYTE_BASE16 = 2;
static final int LONG_BASE16 = BYTE_BASE16 * LONG_BYTES;
private static final String ALPHABET = "0123456789abcdef";
private static final int ASCII_CHARACTERS = 128;
private static final char[] ENCODING = buildEncodingArray();
private static final byte[] DECODING = buildDecodingArray();
private static char[] buildEncodingArray() {
char[] encoding = new char[512];
for (int i = 0; i < 256; ++i) {
encoding[i] = ALPHABET.charAt(i >>> 4);
encoding[i | 0x100] = ALPHABET.charAt(i & 0xF);
}
return encoding;
}
private static byte[] buildDecodingArray() {
byte[] decoding = new byte[ASCII_CHARACTERS];
Arrays.fill(decoding, (byte) -1);
for (int i = 0; i < ALPHABET.length(); i++) {
char c = ALPHABET.charAt(i);
decoding[c] = (byte) i;
}
return decoding;
}
/**
* Returns the {@code long} value.
* @param chars the base8 or base16 representation of the {@code long}.
* @return long array from string. Either contains high and low or just low trace id
*/
public static long[] fromString(CharSequence chars) {
if (chars == null || chars.length() == 0) {
return new long[] { 0 };
}
if (chars.length() == 32) {
long high = HexCodec.lenientLowerHexToUnsignedLong(chars, 0, 16);
long low = HexCodec.lenientLowerHexToUnsignedLong(chars, 16, 32);
return new long[] { high, low };
}
return new long[] { HexCodec.lenientLowerHexToUnsignedLong(chars, 0, 16) };
}
/**
* Returns the {@code long} value whose base16 representation is stored in the first
* 16 chars of {@code chars} starting from the {@code offset}.
* @param chars the base16 representation of the {@code long}.
* @return long value from string
*/
public static long longFromBase16String(CharSequence chars) {
return longFromBase16String(chars, 0);
}
/**
* Returns the {@code long} value whose base16 representation is stored in the first
* 16 chars of {@code chars} starting from the {@code offset}.
* @param chars the base16 representation of the {@code long}.
*/
static long longFromBase16String(CharSequence chars, int offset) {
Assert.isTrue(chars.length() >= offset + LONG_BASE16, "chars too small");
return (decodeByte(chars.charAt(offset), chars.charAt(offset + 1)) & 0xFFL) << 56
| (decodeByte(chars.charAt(offset + 2), chars.charAt(offset + 3)) & 0xFFL) << 48
| (decodeByte(chars.charAt(offset + 4), chars.charAt(offset + 5)) & 0xFFL) << 40
| (decodeByte(chars.charAt(offset + 6), chars.charAt(offset + 7)) & 0xFFL) << 32
| (decodeByte(chars.charAt(offset + 8), chars.charAt(offset + 9)) & 0xFFL) << 24
| (decodeByte(chars.charAt(offset + 10), chars.charAt(offset + 11)) & 0xFFL) << 16
| (decodeByte(chars.charAt(offset + 12), chars.charAt(offset + 13)) & 0xFFL) << 8
| (decodeByte(chars.charAt(offset + 14), chars.charAt(offset + 15)) & 0xFFL);
}
/**
* Decodes the specified two character sequence, and returns the resulting
* {@code byte}.
* @param chars the character sequence to be decoded.
* @param offset the starting offset in the {@code CharSequence}.
* @return the resulting {@code byte}
* @throws IllegalArgumentException if the input is not a valid encoded string
* according to this encoding.
*/
public static byte byteFromBase16String(CharSequence chars, int offset) {
Assert.isTrue(chars.length() >= offset + 2, "chars too small");
return decodeByte(chars.charAt(offset), chars.charAt(offset + 1));
}
private static byte decodeByte(char hi, char lo) {
Assert.isTrue(lo < ASCII_CHARACTERS && DECODING[lo] != -1, "invalid character " + lo);
Assert.isTrue(hi < ASCII_CHARACTERS && DECODING[hi] != -1, "invalid character " + hi);
int decoded = DECODING[hi] << 4 | DECODING[lo];
return (byte) decoded;
}
/**
* Checks if string is valid base16.
* @param value to check
* @return {@code true} if valid base16 string
*/
public static boolean isValidBase16String(CharSequence value) {
for (int i = 0; i < value.length(); i++) {
char b = value.charAt(i);
// 48..57 && 97..102 are valid
if (!isDigit(b) && !isLowercaseHexCharacter(b)) {
return false;
}
}
return true;
}
/**
* Converts long into string.
* @param id 64 bit
* @return string representation of the long
*/
public static String fromLong(long id) {
return fromLongs(0, id);
}
/**
* Converts longs into string.
* @param idHigh - trace id high part
* @param idLow - trace id low part
* @return string representation of the long
*/
public static String fromLongs(long idHigh, long idLow) {
if (idHigh == 0L) {
return HexCodec.toLowerHex(idLow);
}
else {
char[] chars = getTemporaryBuffer();
longToBase16String(idHigh, chars, 0);
longToBase16String(idLow, chars, 16);
return new String(chars);
}
}
public static void longToBase16String(long value, char[] dest, int destOffset) {
byteToBase16((byte) ((int) (value >> 56 & 255L)), dest, destOffset);
byteToBase16((byte) ((int) (value >> 48 & 255L)), dest, destOffset + 2);
byteToBase16((byte) ((int) (value >> 40 & 255L)), dest, destOffset + 4);
byteToBase16((byte) ((int) (value >> 32 & 255L)), dest, destOffset + 6);
byteToBase16((byte) ((int) (value >> 24 & 255L)), dest, destOffset + 8);
byteToBase16((byte) ((int) (value >> 16 & 255L)), dest, destOffset + 10);
byteToBase16((byte) ((int) (value >> 8 & 255L)), dest, destOffset + 12);
byteToBase16((byte) ((int) (value & 255L)), dest, destOffset + 14);
}
public static void byteToBase16(byte value, char[] dest, int destOffset) {
int b = value & 255;
dest[destOffset] = ENCODING[b];
dest[destOffset + 1] = ENCODING[b | 256];
}
private static char[] getTemporaryBuffer() {
char[] chars = charBuffer.get();
if (chars == null) {
chars = new char[32];
charBuffer.set(chars);
}
return chars;
}
private static boolean isLowercaseHexCharacter(char b) {
return 97 <= b && b <= 102;
}
private static boolean isDigit(char b) {
return 48 <= b && b <= 57;
}
}
// taken from brave.internal.codec.HexCodec
final class HexCodec {
private HexCodec() {
throw new IllegalStateException("Can't instantiate a utility class");
}
/**
* Parses a 16 character lower-hex string with no prefix into an unsigned long,
* starting at the specified index.
*
* This reads a trace context a sequence potentially larger than the format. The
* use-case is reducing garbage, by re-using the input {@code value} across multiple
* parse operations.
* @param value the sequence that contains a lower-hex encoded unsigned long.
* @param beginIndex the inclusive begin index: {@linkplain CharSequence#charAt(int)
* index} of the first lower-hex character representing the unsigned long.
*/
static long lowerHexToUnsignedLong(CharSequence value, int beginIndex) {
int endIndex = Math.min(beginIndex + 16, value.length());
long result = lenientLowerHexToUnsignedLong(value, beginIndex, endIndex);
if (result == 0) {
throw isntLowerHexLong(value);
}
return result;
}
/**
* Like {@link #lowerHexToUnsignedLong(CharSequence, int)}, but returns zero on
* invalid input.
* @param value the sequence that contains a lower-hex encoded unsigned long.
* @param beginIndex the inclusive begin index: {@linkplain CharSequence#charAt(int)
* index} of the first lower-hex character representing the unsigned long.
* @param endIndex the exclusive end index: {@linkplain CharSequence#charAt(int)
* index} after the last lower-hex character representing the unsigned long.
*/
static long lenientLowerHexToUnsignedLong(CharSequence value, int beginIndex, int endIndex) {
long result = 0;
int pos = beginIndex;
while (pos < endIndex) {
char c = value.charAt(pos++);
result <<= 4;
if (c >= '0' && c <= '9') {
result |= c - '0';
}
else if (c >= 'a' && c <= 'f') {
result |= c - 'a' + 10;
}
else {
return 0;
}
}
return result;
}
static NumberFormatException isntLowerHexLong(CharSequence lowerHex) {
throw new NumberFormatException(lowerHex + " should be a 1 to 32 character lower-hex string with no prefix");
}
/** Inspired by {@code okio.Buffer.writeLong}. */
static String toLowerHex(long v) {
char[] data = RecyclableBuffers.parseBuffer();
writeHexLong(data, 0, v);
return new String(data, 0, 16);
}
/** Inspired by {@code okio.Buffer.writeLong}. */
static void writeHexLong(char[] data, int pos, long v) {
writeHexByte(data, pos + 0, (byte) ((v >>> 56L) & 0xff));
writeHexByte(data, pos + 2, (byte) ((v >>> 48L) & 0xff));
writeHexByte(data, pos + 4, (byte) ((v >>> 40L) & 0xff));
writeHexByte(data, pos + 6, (byte) ((v >>> 32L) & 0xff));
writeHexByte(data, pos + 8, (byte) ((v >>> 24L) & 0xff));
writeHexByte(data, pos + 10, (byte) ((v >>> 16L) & 0xff));
writeHexByte(data, pos + 12, (byte) ((v >>> 8L) & 0xff));
writeHexByte(data, pos + 14, (byte) (v & 0xff));
}
static final char[] HEX_DIGITS = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
static void writeHexByte(char[] data, int pos, byte b) {
data[pos + 0] = HEX_DIGITS[(b >> 4) & 0xf];
data[pos + 1] = HEX_DIGITS[b & 0xf];
}
}
// taken from brave
final class RecyclableBuffers {
private RecyclableBuffers() {
throw new IllegalStateException("Can't instantiate a utility class");
}
private static final ThreadLocal<char[]> PARSE_BUFFER = new ThreadLocal<>();
/**
* Returns a {@link ThreadLocal} reused {@code char[]} for use when decoding bytes
* into an ID hex string. The buffer should be immediately copied into a
* {@link String} after decoding within the same method.
*/
static char[] parseBuffer() {
char[] idBuffer = PARSE_BUFFER.get();
if (idBuffer == null) {
idBuffer = new char[32 + 1 + 16 + 3 + 16]; // traceid128-spanid-1-parentid
PARSE_BUFFER.set(idBuffer);
}
return idBuffer;
}
}