1 #include <libcper/base64.h>
2 #include <libcper/BaseTypes.h>
3
4 #include <stdlib.h>
5 #include <string.h>
6 #include <stdio.h>
7 #include <assert.h>
8
9 static const UINT8 encode_table[65] =
10 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
11
12 /**
13 *
14 * Caller is responsible for freeing the returned buffer.
15 */
base64_encode(const UINT8 * src,INT32 len,INT32 * out_len)16 CHAR8 *base64_encode(const UINT8 *src, INT32 len, INT32 *out_len)
17 {
18 CHAR8 *out;
19 CHAR8 *out_pos;
20 const UINT8 *src_end;
21 const UINT8 *in_pos;
22
23 if (len <= 0) {
24 return NULL;
25 }
26
27 if (!out_len) {
28 return NULL;
29 }
30
31 // 3 byte blocks to 4 byte blocks plus up to 2 bytes of padding
32 *out_len = 4 * ((len + 2) / 3);
33
34 // Handle overflows
35 if (*out_len < len) {
36 return NULL;
37 }
38
39 out = malloc(*out_len);
40 if (out == NULL) {
41 return NULL;
42 }
43
44 src_end = src + len;
45 in_pos = src;
46 out_pos = out;
47 while (src_end - in_pos >= 3) {
48 *out_pos++ = encode_table[in_pos[0] >> 2];
49 *out_pos++ = encode_table[((in_pos[0] & 0x03) << 4) |
50 (in_pos[1] >> 4)];
51 *out_pos++ = encode_table[((in_pos[1] & 0x0f) << 2) |
52 (in_pos[2] >> 6)];
53 *out_pos++ = encode_table[in_pos[2] & 0x3f];
54 in_pos += 3;
55 }
56
57 if (src_end - in_pos) {
58 *out_pos++ = encode_table[in_pos[0] >> 2];
59 if (src_end - in_pos == 1) {
60 *out_pos++ = encode_table[(in_pos[0] & 0x03) << 4];
61 *out_pos++ = '=';
62 } else {
63 *out_pos++ = encode_table[((in_pos[0] & 0x03) << 4) |
64 (in_pos[1] >> 4)];
65 *out_pos++ = encode_table[(in_pos[1] & 0x0f) << 2];
66 }
67 *out_pos++ = '=';
68 }
69
70 return out;
71 }
72
73 // Base64 decode table. Invalid values are specified with 0x80.
74 UINT8 decode_table[256] =
75 "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80"
76 "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80"
77 "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x3e\x80\x80\x80\x3f"
78 "\x34\x35\x36\x37\x38\x39\x3a\x3b\x3c\x3d\x80\x80\x80\x00\x80\x80"
79 "\x80\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e"
80 "\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x80\x80\x80\x80\x80"
81 "\x80\x1a\x1b\x1c\x1d\x1e\x1f\x20\x21\x22\x23\x24\x25\x26\x27\x28"
82 "\x29\x2a\x2b\x2c\x2d\x2e\x2f\x30\x31\x32\x33\x80\x80\x80\x80\x80"
83 "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80"
84 "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80"
85 "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80"
86 "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80"
87 "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80"
88 "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80"
89 "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80"
90 "\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80\x80";
91
92 /**
93 *
94 * Caller is responsible for freeing the returned buffer.
95 */
base64_decode(const CHAR8 * src,INT32 len,INT32 * out_len)96 UINT8 *base64_decode(const CHAR8 *src, INT32 len, INT32 *out_len)
97 {
98 UINT8 *out = NULL;
99 UINT8 *pos = NULL;
100 UINT8 block[4];
101 INT32 block_index = 0;
102 INT32 src_index = 0;
103
104 if (!out_len) {
105 goto error;
106 }
107
108 // Malloc might be up to 2 larger dependent on padding
109 *out_len = len / 4 * 3 + 2;
110 pos = out = malloc(*out_len);
111 if (out == NULL) {
112 goto error;
113 }
114
115 block_index = 0;
116 for (src_index = 0; src_index < len; src_index++) {
117 char current_char = src[src_index];
118 if (current_char == '=') {
119 break;
120 }
121 // If the final character is a newline, as can occur in many editors
122 // then ignore it.
123 if (src_index + 1 == len && current_char == '\n') {
124 printf("Ignoring trailing newline.\n");
125 break;
126 }
127
128 block[block_index] = decode_table[(UINT8)current_char];
129 if (block[block_index] == 0x80) {
130 printf("Invalid character \"%c\".\n", current_char);
131 goto error;
132 }
133
134 block_index++;
135 if (block_index == 4) {
136 *pos++ = (block[0] << 2) | (block[1] >> 4);
137 *pos++ = (block[1] << 4) | (block[2] >> 2);
138 *pos++ = (block[2] << 6) | block[3];
139 block_index = 0;
140 }
141 }
142 if (block_index == 0) {
143 // mod 4 Even number of characters, no padding.
144 } else if (block_index == 1) {
145 printf("Invalid base64 input length. Last character truncated.\n");
146 goto error;
147 } else if (block_index == 2) {
148 *pos++ = (block[0] << 2) | (block[1] >> 4);
149 } else if (block_index == 3) {
150 *pos++ = (block[0] << 2) | (block[1] >> 4);
151 *pos++ = (block[1] << 4) | (block[2] >> 2);
152 } else {
153 /* Invalid pad_counting */
154 printf("Invalid base64 input length %d.\n", block_index);
155 goto error;
156 }
157
158 *out_len = pos - out;
159 return out;
160
161 error:
162 free(out);
163 return NULL;
164 }
165