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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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package org.apache.solr.common.util;
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* Static methods for translating Base64 encoded strings to byte arrays
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* This array is a lookup table that translates 6-bit positive integer
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* index values into their "Base64 Alphabet" equivalents as specified
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* in Table 1 of RFC 2045.
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private static final char intToBase64[] = {
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'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M',
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'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
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'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm',
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'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z',
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'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'
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* This array is a lookup table that translates unicode characters
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* drawn from the "Base64 Alphabet" (as specified in Table 1 of RFC 2045)
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* into their 6-bit positive integer equivalents. Characters that
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* are not in the Base64 alphabet but fall within the bounds of the
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* array are translated to -1.
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private static final byte base64ToInt[] = {
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54,
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55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4,
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5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23,
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24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34,
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35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51
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public static String byteArrayToBase64(byte[] a, int offset, int len) {
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int numFullGroups = aLen / 3;
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int numBytesInPartialGroup = aLen - 3 * numFullGroups;
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int resultLen = 4 * ((aLen + 2) / 3);
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StringBuffer result = new StringBuffer(resultLen);
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char[] intToAlpha = intToBase64;
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// Translate all full groups from byte array elements to Base64
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int inCursor = offset;
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for (int i = 0; i < numFullGroups; i++) {
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int byte0 = a[inCursor++] & 0xff;
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int byte1 = a[inCursor++] & 0xff;
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int byte2 = a[inCursor++] & 0xff;
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result.append(intToAlpha[byte0 >> 2]);
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result.append(intToAlpha[(byte0 << 4) & 0x3f | (byte1 >> 4)]);
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result.append(intToAlpha[(byte1 << 2) & 0x3f | (byte2 >> 6)]);
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result.append(intToAlpha[byte2 & 0x3f]);
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// Translate partial group if present
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if (numBytesInPartialGroup != 0) {
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int byte0 = a[inCursor++] & 0xff;
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result.append(intToAlpha[byte0 >> 2]);
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if (numBytesInPartialGroup == 1) {
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result.append(intToAlpha[(byte0 << 4) & 0x3f]);
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// assert numBytesInPartialGroup == 2;
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int byte1 = a[inCursor++] & 0xff;
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result.append(intToAlpha[(byte0 << 4) & 0x3f | (byte1 >> 4)]);
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result.append(intToAlpha[(byte1 << 2) & 0x3f]);
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return result.toString();
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public static byte[] base64ToByteArray(String s) {
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byte[] alphaToInt = base64ToInt;
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int sLen = s.length();
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int numGroups = sLen / 4;
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if (4 * numGroups != sLen)
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throw new IllegalArgumentException(
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"String length must be a multiple of four.");
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int missingBytesInLastGroup = 0;
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int numFullGroups = numGroups;
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if (s.charAt(sLen - 1) == '=') {
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missingBytesInLastGroup++;
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if (s.charAt(sLen - 2) == '=')
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missingBytesInLastGroup++;
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byte[] result = new byte[3 * numGroups - missingBytesInLastGroup];
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// Translate all full groups from base64 to byte array elements
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int inCursor = 0, outCursor = 0;
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for (int i = 0; i < numFullGroups; i++) {
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int ch0 = base64toInt(s.charAt(inCursor++), alphaToInt);
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int ch1 = base64toInt(s.charAt(inCursor++), alphaToInt);
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int ch2 = base64toInt(s.charAt(inCursor++), alphaToInt);
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int ch3 = base64toInt(s.charAt(inCursor++), alphaToInt);
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result[outCursor++] = (byte) ((ch0 << 2) | (ch1 >> 4));
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result[outCursor++] = (byte) ((ch1 << 4) | (ch2 >> 2));
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result[outCursor++] = (byte) ((ch2 << 6) | ch3);
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// Translate partial group, if present
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if (missingBytesInLastGroup != 0) {
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int ch0 = base64toInt(s.charAt(inCursor++), alphaToInt);
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int ch1 = base64toInt(s.charAt(inCursor++), alphaToInt);
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result[outCursor++] = (byte) ((ch0 << 2) | (ch1 >> 4));
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if (missingBytesInLastGroup == 1) {
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int ch2 = base64toInt(s.charAt(inCursor++), alphaToInt);
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result[outCursor++] = (byte) ((ch1 << 4) | (ch2 >> 2));
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// assert inCursor == s.length()-missingBytesInLastGroup;
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// assert outCursor == result.length;
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* Translates the specified character, which is assumed to be in the
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* "Base 64 Alphabet" into its equivalent 6-bit positive integer.
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* @throw IllegalArgumentException or ArrayOutOfBoundsException if
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* c is not in the Base64 Alphabet.
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private static int base64toInt(char c, byte[] alphaToInt) {
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int result = alphaToInt[c];
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throw new IllegalArgumentException("Illegal character " + c);