xref: /btstack/src/btstack_base64_decoder.c (revision 4ea43905e81e6bfa244dfdbd768b1d4e9664a403) 
1 /*
2  * Copyright (C) 2018 BlueKitchen GmbH
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  *
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. Neither the name of the copyright holders nor the names of
14  *    contributors may be used to endorse or promote products derived
15  *    from this software without specific prior written permission.
16  * 4. Any redistribution, use, or modification is done solely for
17  *    personal benefit and not for any commercial purpose or for
18  *    monetary gain.
19  *
20  * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS
21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
23  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MATTHIAS
24  * RINGWALD OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
26  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
27  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
28  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
29  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
30  * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  *
33  * Please inquire about commercial licensing options at
34  * [email protected]
35  *
36  */
37 
38 #define BTSTACK_FILE__ "btstack_base64_decoder.c"
39 
40 /*
41  *  btstack_base64_decoder.c
42  */
43 
44 #include "btstack_base64_decoder.h"
45 #include <string.h>
46 
47 /**
48  * @brief Initialize base99 decoder
49  * @param context
50  */
51 void btstack_base64_decoder_init(btstack_base64_decoder_t * context){
52     memset(context, 0, sizeof(btstack_base64_decoder_t));
53 }
54 
55 /**
56  * @brief Decode single byte
57  * @param context
58  * @returns value, or BTSTACK_BASE64_DECODER_COMPLETE, BTSTACK_BASE64_DECODER_INVALID
59  */
60 int  btstack_base64_decoder_process_byte(btstack_base64_decoder_t * context, uint8_t c){
61 
62     // map ascii char to 6-bit value
63     static const uint8_t table[256] = {
64             99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
65             99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
66             99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 62, 99, 99, 99, 63,
67             52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 99, 99, 99, 99, 99, 99,
68             99,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
69             15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 99, 99, 99, 99, 99,
70             99, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
71             41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 99, 99, 99, 99, 99,
72             99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
73             99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
74             99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
75             99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
76             99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
77             99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
78             99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
79             99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99
80     };
81 
82     // handle '='
83     if (c == '='){
84         if ((context->pos == 2u) || (context->pos == 3u)){
85             context->pos++;
86             return BTSTACK_BASE64_DECODER_MORE;
87         }
88     }
89 
90     // lookup
91     uint8_t value = table[c];
92 
93     // invalid character
94     if (value == 99u) {
95         context->pos = 99;
96     }
97 
98     int result = 0;
99     switch (context->pos){
100         case 0:
101             context->value = value; // 6 bit
102             context->pos++;
103             result = BTSTACK_BASE64_DECODER_MORE;
104             break;
105         case 1:
106             result = (context->value << 2) | (value >> 4);
107             context->value = value; // 4 bit
108             context->pos++;
109             break;
110         case 2:
111             result = (context->value << 4) | (value >> 2);
112             context->value = value; // 2 bit
113             context->pos++;
114             break;
115         case 3:
116             result = (context->value << 6) | value;
117             context->pos = 0;       // done
118             break;
119         case 99:
120             result = BTSTACK_BASE64_DECODER_INVALID;
121             break;
122     }
123     return result;
124 }
125 
126 int btstack_base64_decoder_process_block(const uint8_t * input_data, uint32_t input_size, uint8_t * output_buffer, uint32_t output_max_size){
127     btstack_base64_decoder_t context;
128     btstack_base64_decoder_init(&context);
129     uint32_t size = 0;
130     while (input_size){
131         uint8_t data = *input_data++;
132         int result = btstack_base64_decoder_process_byte(&context, data);
133         input_size--;
134         switch (result){
135             case BTSTACK_BASE64_DECODER_MORE:
136                 break;
137             case BTSTACK_BASE64_DECODER_INVALID:
138                 return BTSTACK_BASE64_DECODER_INVALID;
139             default:
140                 if (size >= output_max_size){
141                     return BTSTACK_BASE64_DECODER_FULL;
142                 }
143                 output_buffer[size++] = result;
144                 break;
145         }
146     }
147     return size;
148 }
149