1 /**
2  * Licensed to the Apache Software Foundation (ASF) under one
3  * or more contributor license agreements. See the NOTICE file
4  * distributed with this work for additional information
5  * regarding copyright ownership. The ASF licenses this file
6  * to you under the Apache License, Version 2.0 (the
7  * "License"); you may not use this file except in compliance
8  * with the License. You may obtain a copy of the License at
9  *
10  *   http://www.apache.org/licenses/LICENSE-2.0
11  *
12  * Unless required by applicable law or agreed to in writing,
13  * software distributed under the License is distributed on an
14  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15  * KIND, either express or implied. See the License for the
16  * specific language governing permissions and limitations
17  * under the License.
18  */
19 
20 using System;
21 
22 namespace Thrift.Protocol
23 {
24     internal static class TBase64Utils
25     {
26         internal const string ENCODE_TABLE =
27             "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
28 
encode(byte[] src, int srcOff, int len, byte[] dst, int dstOff)29         internal static void encode(byte[] src, int srcOff, int len, byte[] dst,
30                                 int dstOff)
31         {
32             dst[dstOff] = (byte)ENCODE_TABLE[(src[srcOff] >> 2) & 0x3F];
33             if (len == 3)
34             {
35                 dst[dstOff + 1] =
36                     (byte)ENCODE_TABLE[
37                         ((src[srcOff] << 4) & 0x30) | ((src[srcOff + 1] >> 4) & 0x0F)];
38                 dst[dstOff + 2] =
39                     (byte)ENCODE_TABLE[
40                         ((src[srcOff + 1] << 2) & 0x3C) | ((src[srcOff + 2] >> 6) & 0x03)];
41                 dst[dstOff + 3] =
42                     (byte)ENCODE_TABLE[src[srcOff + 2] & 0x3F];
43             }
44             else if (len == 2)
45             {
46                 dst[dstOff + 1] =
47                     (byte)ENCODE_TABLE[
48                         ((src[srcOff] << 4) & 0x30) | ((src[srcOff + 1] >> 4) & 0x0F)];
49                 dst[dstOff + 2] =
50                     (byte)ENCODE_TABLE[(src[srcOff + 1] << 2) & 0x3C];
51 
52             }
53             else
54             { // len == 1) {
55                 dst[dstOff + 1] =
56                     (byte)ENCODE_TABLE[(src[srcOff] << 4) & 0x30];
57             }
58         }
59 
60         private static int[] DECODE_TABLE = {
61             -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
62             -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
63             -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,62,-1,-1,-1,63,
64             52,53,54,55,56,57,58,59,60,61,-1,-1,-1,-1,-1,-1,
65             -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,10,11,12,13,14,
66             15,16,17,18,19,20,21,22,23,24,25,-1,-1,-1,-1,-1,
67             -1,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,
68             41,42,43,44,45,46,47,48,49,50,51,-1,-1,-1,-1,-1,
69             -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
70             -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
71             -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
72             -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
73             -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
74             -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
75             -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
76             -1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
77         };
78 
decode(byte[] src, int srcOff, int len, byte[] dst, int dstOff)79         internal static void decode(byte[] src, int srcOff, int len, byte[] dst,
80                                  int dstOff)
81         {
82             dst[dstOff] = (byte)
83                 ((DECODE_TABLE[src[srcOff] & 0x0FF] << 2) |
84                 (DECODE_TABLE[src[srcOff + 1] & 0x0FF] >> 4));
85             if (len > 2)
86             {
87                 dst[dstOff + 1] = (byte)
88                     (((DECODE_TABLE[src[srcOff + 1] & 0x0FF] << 4) & 0xF0) |
89                     (DECODE_TABLE[src[srcOff + 2] & 0x0FF] >> 2));
90                 if (len > 3)
91                 {
92                     dst[dstOff + 2] = (byte)
93                         (((DECODE_TABLE[src[srcOff + 2] & 0x0FF] << 6) & 0xC0) |
94                         DECODE_TABLE[src[srcOff + 3] & 0x0FF]);
95                 }
96             }
97         }
98 
99     }
100 }
101