xref: /btstack/src/btstack_base64_decoder.c (revision a8d51f092f1b660d0f6921369ad2bc3f9368296c) 
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 "btstack_debug.h"
46 #include <string.h>
47 
48 /**
49  * @brief Initialize base99 decoder
50  * @param context
51  */
52 void btstack_base64_decoder_init(btstack_base64_decoder_t * context){
53     memset(context, 0, sizeof(btstack_base64_decoder_t));
54 }
55 
56 /**
57  * @brief Decode single byte
58  * @param context
59  * @returns value, or BTSTACK_BASE64_DECODER_COMPLETE, BTSTACK_BASE64_DECODER_INVALID
60  */
61 int  btstack_base64_decoder_process_byte(btstack_base64_decoder_t * context, uint8_t c){
62 
63     // map ascii char to 6-bit value
64     static const uint8_t table[256] = {
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, 99, 99, 99, 99, 99,
67             99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 62, 99, 99, 99, 63,
68             52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 99, 99, 99, 99, 99, 99,
69             99,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
70             15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 99, 99, 99, 99, 99,
71             99, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
72             41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 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             99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99
81     };
82 
83     // handle '='
84     if (c == '='){
85         if ((context->pos == 2u) || (context->pos == 3u)){
86             context->pos++;
87             return BTSTACK_BASE64_DECODER_MORE;
88         }
89     }
90 
91     // lookup
92     uint8_t value = table[c];
93 
94     // invalid character
95     if (value == 99u) {
96         context->pos = 99;
97     }
98 
99     int result = 0;
100     switch (context->pos){
101         case 0:
102             context->value = value; // 6 bit
103             context->pos++;
104             result = BTSTACK_BASE64_DECODER_MORE;
105             break;
106         case 1:
107             result = (context->value << 2) | (value >> 4);
108             context->value = value; // 4 bit
109             context->pos++;
110             break;
111         case 2:
112             result = (context->value << 4) | (value >> 2);
113             context->value = value; // 2 bit
114             context->pos++;
115             break;
116         case 3:
117             result = (context->value << 6) | value;
118             context->pos = 0;       // done
119             break;
120         case 99:
121             result = BTSTACK_BASE64_DECODER_INVALID;
122             break;
123 		default:
124 			btstack_assert(false);
125 			break;
126     }
127     return result;
128 }
129 
130 int btstack_base64_decoder_process_block(const uint8_t * input_data, uint32_t input_size, uint8_t * output_buffer, uint32_t output_max_size){
131     btstack_base64_decoder_t context;
132     btstack_base64_decoder_init(&context);
133     uint32_t size = 0;
134     while (input_size){
135         uint8_t data = *input_data++;
136         int result = btstack_base64_decoder_process_byte(&context, data);
137         input_size--;
138         switch (result){
139             case BTSTACK_BASE64_DECODER_MORE:
140                 break;
141             case BTSTACK_BASE64_DECODER_INVALID:
142                 return BTSTACK_BASE64_DECODER_INVALID;
143             default:
144                 if (size >= output_max_size){
145                     return BTSTACK_BASE64_DECODER_FULL;
146                 }
147                 output_buffer[size++] = result;
148                 break;
149         }
150     }
151     return size;
152 }
153