/*
* Copyright 2015 The Netty Project
*
* The Netty Project licenses this file to you 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.
*/
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 io.netty.handler.codec.http2;
/**
* Extracted from org/apache/commons/codec/binary/Hex.java Copyright Apache Software Foundation
*/
final class HpackHex {
private HpackHex() {
}
/**
* Used to build output as HpackHex
*/
private static final char[] DIGITS_LOWER =
{'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
/**
* Used to build output as HpackHex
*/
private static final char[] DIGITS_UPPER =
{'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
/**
* Converts an array of characters representing hexadecimal values into an array of bytes of
* those same values. The returned array will be half the length of the passed array, as it
* takes two characters to represent any given byte. An exception is thrown if the passed char
* array has an odd number of elements.
*
* @param data An array of characters containing hexadecimal digits
* @return A byte array containing binary data decoded from the supplied char array.
* @throws IllegalArgumentException Thrown if an odd number or illegal of characters is supplied
*/
public static byte[] decodeHex(char[] data) {
int len = data.length;
if ((len & 0x01) != 0) {
throw new IllegalArgumentException("Odd number of characters.");
}
byte[] out = new byte[len >> 1];
// two characters form the hex value.
for (int i = 0, j = 0; j < len; i++) {
int f = toDigit(data[j], j) << 4;
j++;
f = f | toDigit(data[j], j);
j++;
out[i] = (byte) (f & 0xFF);
}
return out;
}
/**
* Converts an array of bytes into an array of characters representing the hexadecimal values of
* each byte in order. The returned array will be double the length of the passed array, as it
* takes two characters to represent any given byte.
*
* @param data a byte[] to convert to HpackHex characters
* @return A char[] containing hexadecimal characters
*/
public static char[] encodeHex(byte[] data) {
return encodeHex(data, true);
}
/**
* Converts an array of bytes into an array of characters representing the hexadecimal values of
* each byte in order. The returned array will be double the length of the passed array, as it
* takes two characters to represent any given byte.
*
* @param data a byte[] to convert to HpackHex characters
* @param toLowerCase <code>true</code> converts to lowercase, <code>false</code> to uppercase
* @return A char[] containing hexadecimal characters
* @since 1.4
*/
public static char[] encodeHex(byte[] data, boolean toLowerCase) {
return encodeHex(data, toLowerCase ? DIGITS_LOWER : DIGITS_UPPER);
}
/**
* Converts an array of bytes into an array of characters representing the hexadecimal values of
* each byte in order. The returned array will be double the length of the passed array, as it
* takes two characters to represent any given byte.
*
* @param data a byte[] to convert to HpackHex characters
* @param toDigits the output alphabet
* @return A char[] containing hexadecimal characters
* @since 1.4
*/
protected static char[] encodeHex(byte[] data, char[] toDigits) {
int l = data.length;
char[] out = new char[l << 1];
// two characters form the hex value.
for (int i = 0, j = 0; i < l; i++) {
out[j++] = toDigits[(0xF0 & data[i]) >>> 4];
out[j++] = toDigits[0x0F & data[i]];
}
return out;
}
/**
* Converts an array of bytes into a String representing the hexadecimal values of each byte in
* order. The returned String will be double the length of the passed array, as it takes two
* characters to represent any given byte.
*
* @param data a byte[] to convert to HpackHex characters
* @return A String containing hexadecimal characters
* @since 1.4
*/
public static String encodeHexString(byte[] data) {
return new String(encodeHex(data));
}
/**
* Converts a hexadecimal character to an integer.
*
* @param ch A character to convert to an integer digit
* @param index The index of the character in the source
* @return An integer
* @throws IllegalArgumentException Thrown if ch is an illegal hex character
*/
protected static int toDigit(char ch, int index) throws IllegalArgumentException {
int digit = Character.digit(ch, 16);
if (digit == -1) {
throw new IllegalArgumentException("Illegal hexadecimal character " + ch + " at index " + index);
}
return digit;
}
}