/*
* 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 org.apache.thrift.protocol;
/**
* Class for encoding and decoding Base64 data.
*
* This class is kept at package level because the interface does no input
* validation and is therefore too low-level for generalized reuse.
*
* Note also that the encoding does not pad with equal signs , as discussed in
* section 2.2 of the RFC (http://www.faqs.org/rfcs/rfc3548.html). Furthermore,
* bad data encountered when decoding is neither rejected or ignored but simply
* results in bad decoded data -- this is not in compliance with the RFC but is
* done in the interest of performance.
*
*/
class TBase64Utils {
private static final String ENCODE_TABLE =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
/**
* Encode len bytes of data in src at offset srcOff, storing the result into
* dst at offset dstOff. len must be 1, 2, or 3. dst must have at least len+1
* bytes of space at dstOff. src and dst should not be the same object. This
* method does no validation of the input values in the interest of
* performance.
*
* @param src the source of bytes to encode
* @param srcOff the offset into the source to read the unencoded bytes
* @param len the number of bytes to encode (must be 1, 2, or 3).
* @param dst the destination for the encoding
* @param dstOff the offset into the destination to place the encoded bytes
*/
static final void encode(byte[] src, int srcOff, int len, byte[] dst,
int dstOff) {
dst[dstOff] = (byte)ENCODE_TABLE.charAt((src[srcOff] >> 2) & 0x3F);
if (len == 3) {
dst[dstOff + 1] =
(byte)ENCODE_TABLE.charAt(
((src[srcOff] << 4) + (src[srcOff+1] >> 4)) & 0x3F);
dst[dstOff + 2] =
(byte)ENCODE_TABLE.charAt(
((src[srcOff+1] << 2) + (src[srcOff+2] >> 6)) & 0x3F);
dst[dstOff + 3] =
(byte)ENCODE_TABLE.charAt(src[srcOff+2] & 0x3F);
}
else if (len == 2) {
dst[dstOff+1] =
(byte)ENCODE_TABLE.charAt(
((src[srcOff] << 4) + (src[srcOff+1] >> 4)) & 0x3F);
dst[dstOff + 2] =
(byte)ENCODE_TABLE.charAt((src[srcOff+1] << 2) & 0x3F);
}
else { // len == 1) {
dst[dstOff + 1] =
(byte)ENCODE_TABLE.charAt((src[srcOff] << 4) & 0x3F);
}
}
private static final byte[] DECODE_TABLE = {
-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,62,-1,-1,-1,63,
52,53,54,55,56,57,58,59,60,61,-1,-1,-1,-1,-1,-1,
-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10,11,12,13,14,
15,16,17,18,19,20,21,22,23,24,25,-1,-1,-1,-1,-1,
-1,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,
41,42,43,44,45,46,47,48,49,50,51,-1,-1,-1,-1,-1,
-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
};
/**
* Decode len bytes of data in src at offset srcOff, storing the result into
* dst at offset dstOff. len must be 2, 3, or 4. dst must have at least len-1
* bytes of space at dstOff. src and dst may be the same object as long as
* dstoff <= srcOff. This method does no validation of the input values in
* the interest of performance.
*
* @param src the source of bytes to decode
* @param srcOff the offset into the source to read the encoded bytes
* @param len the number of bytes to decode (must be 2, 3, or 4)
* @param dst the destination for the decoding
* @param dstOff the offset into the destination to place the decoded bytes
*/
static final void decode(byte[] src, int srcOff, int len, byte[] dst,
int dstOff) {
dst[dstOff] = (byte)
((DECODE_TABLE[src[srcOff] & 0x0FF] << 2) |
(DECODE_TABLE[src[srcOff+1] & 0x0FF] >> 4));
if (len > 2) {
dst[dstOff+1] = (byte)
(((DECODE_TABLE[src[srcOff+1] & 0x0FF] << 4) & 0xF0) |
(DECODE_TABLE[src[srcOff+2] & 0x0FF] >> 2));
if (len > 3) {
dst[dstOff+2] = (byte)
(((DECODE_TABLE[src[srcOff+2] & 0x0FF] << 6) & 0xC0) |
DECODE_TABLE[src[srcOff+3] & 0x0FF]);
}
}
}
}