xref: /btstack/src/btstack_base64_decoder.c (revision 80e33422a96c028b3a9c308fc4b9b874712dafb4) 
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 /*
39  *  btstack_base64_decoder.c
40  */
41 
42 #include "btstack_base64_decoder.h"
43 #include <string.h>
44 #include <stdio.h>
45 
46 // map ascii char to 6-bit value
47 static const uint8_t table[256] = {
48     99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
49     99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
50     99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 62, 99, 99, 99, 63,
51     52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 99, 99, 99, 99, 99, 99,
52     99,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
53     15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 99, 99, 99, 99, 99,
54     99, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
55     41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 99, 99, 99, 99, 99,
56     99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
57     99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
58     99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
59     99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
60     99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
61     99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
62     99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99,
63     99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99
64 };
65 
66 /**
67  * @brief Initialize base99 decoder
68  * @param context
69  */
70 void btstack_base64_decoder_init(btstack_base64_decoder_t * context){
71     memset(context, 0, sizeof(btstack_base64_decoder_t));
72 }
73 
74 /**
75  * @brief Decode single byte
76  * @param context
77  * @returns value, or BTSTACK_BASE64_DECODER_COMPLETE, BTSTACK_BASE64_DECODER_INVALID
78  */
79 int  btstack_base64_decoder_process_byte(btstack_base64_decoder_t * context, uint8_t c){
80 
81     // handle '='
82     if (c == '='){
83         if (context->pos == 2 || context->pos == 3){
84             context->pos++;
85             return BTSTACK_BASE64_DECODER_MORE;
86         }
87     }
88 
89     // lookup
90     uint8_t value = table[c];
91 
92     // invalid character
93     if (value == 99) {
94         context->pos = 99;
95     }
96 
97     int result = 0;
98     switch (context->pos){
99         case 0:
100             context->value = value; // 6 bit
101             context->pos++;
102             result = BTSTACK_BASE64_DECODER_MORE;
103             break;
104         case 1:
105             result = (context->value << 2) | (value >> 4);
106             context->value = value; // 4 bit
107             context->pos++;
108             break;
109         case 2:
110             result = (context->value << 4) | (value >> 2);
111             context->value = value; // 2 bit
112             context->pos++;
113             break;
114         case 3:
115             result = (context->value << 6) | value;
116             context->pos = 0;       // done
117             break;
118         case 99:
119             result = BTSTACK_BASE64_DECODER_INVALID;
120             break;
121     }
122     return result;
123 }
124 
125 int btstack_base64_decoder_process_block(const uint8_t * input_data, uint32_t input_size, uint8_t * output_buffer, uint32_t output_max_size){
126     btstack_base64_decoder_t context;
127     btstack_base64_decoder_init(&context);
128     uint32_t size = 0;
129     while (input_size){
130         uint8_t data = *input_data++;
131         int result = btstack_base64_decoder_process_byte(&context, data);
132         input_size--;
133         switch (result){
134             case BTSTACK_BASE64_DECODER_MORE:
135                 break;
136             case BTSTACK_BASE64_DECODER_INVALID:
137                 return BTSTACK_BASE64_DECODER_INVALID;
138             default:
139                 if (size >= output_max_size){
140                     return BTSTACK_BASE64_DECODER_FULL;
141                 }
142                 output_buffer[size++] = result;
143                 break;
144         }
145     }
146     return size;
147 }
148