1: #include "first.h"
2:
3: #include "base64.h"
4:
5: /* reverse mapping:
6: * >= 0: base64 value
7: * -1: invalid character
8: * -2: skip character (whitespace/control)
9: * -3: padding
10: */
11:
12: /* BASE64_STANDARD: "A-Z a-z 0-9 + /" maps to 0-63, pad with "=" */
13: static const char base64_standard_table[66] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
14: static const short base64_standard_reverse_table[128] = {
15: /* 0 1 2 3 4 5 6 7 8 9 A B C D E F */
16: -1, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, /* 0x00 - 0x0F */
17: -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, /* 0x10 - 0x1F */
18: -2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, /* 0x20 - 0x2F */
19: 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -3, -1, -1, /* 0x30 - 0x3F */
20: -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 0x40 - 0x4F */
21: 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, /* 0x50 - 0x5F */
22: -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, /* 0x60 - 0x6F */
23: 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1, /* 0x70 - 0x7F */
24: };
25:
26: /* BASE64_URL: "A-Z a-z 0-9 - _" maps to 0-63, pad with "." */
27: static const char base64_url_table[66] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_.";
28: static const short base64_url_reverse_table[128] = {
29: /* 0 1 2 3 4 5 6 7 8 9 A B C D E F */
30: -1, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, /* 0x00 - 0x0F */
31: -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, /* 0x10 - 0x1F */
32: -2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -3, -1, /* 0x20 - 0x2F */
33: 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, /* 0x30 - 0x3F */
34: -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, /* 0x40 - 0x4F */
35: 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, 63, /* 0x50 - 0x5F */
36: -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, /* 0x60 - 0x6F */
37: 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1, /* 0x70 - 0x7F */
38: };
39:
40: unsigned char* buffer_append_base64_decode(buffer *out, const char* in, size_t in_length, base64_charset charset) {
41: unsigned char *result;
42: size_t out_pos = 0; /* current output character (position) that is decoded. can contain partial result */
43: unsigned int group = 0; /* how many base64 digits in the current group were decoded already. each group has up to 4 digits */
44: size_t i;
45: const short* base64_reverse_table;
46:
47: switch (charset) {
48: case BASE64_STANDARD:
49: base64_reverse_table = base64_standard_reverse_table;
50: break;
51: case BASE64_URL:
52: base64_reverse_table = base64_url_reverse_table;
53: break;
54: default:
55: return NULL;
56: }
57:
58: result = (unsigned char *) buffer_string_prepare_append(out, 3*(in_length / 4) + 3);
59:
60: /* run through the whole string, converting as we go */
61: for (i = 0; i < in_length; i++) {
62: unsigned char c = (unsigned char) in[i];
63: short ch;
64:
65: if (c == '\0') break;
66: if (c >= 128) return NULL; /* only 7-bit characters allowed */
67:
68: ch = base64_reverse_table[c];
69: if (-3 == ch) {
70: /* pad character; can only come after 2 base64 digits in a group */
71: if (group < 2) return NULL;
72: break;
73: } else if (-2 == ch) {
74: continue; /* skip character */
75: } else if (ch < 0) {
76: return NULL; /* invalid character, abort */
77: }
78:
79: switch(group) {
80: case 0:
81: result[out_pos] = ch << 2;
82: group = 1;
83: break;
84: case 1:
85: result[out_pos++] |= ch >> 4;
86: result[out_pos] = (ch & 0x0f) << 4;
87: group = 2;
88: break;
89: case 2:
90: result[out_pos++] |= ch >>2;
91: result[out_pos] = (ch & 0x03) << 6;
92: group = 3;
93: break;
94: case 3:
95: result[out_pos++] |= ch;
96: group = 0;
97: break;
98: }
99: }
100:
101: switch(group) {
102: case 0:
103: /* ended on boundary */
104: break;
105: case 1:
106: /* need at least 2 base64 digits per group */
107: return NULL;
108: case 2:
109: /* have 2 base64 digits in last group => one real octect, two zeroes padded */
110: case 3:
111: /* have 3 base64 digits in last group => two real octects, one zero padded */
112:
113: /* for both cases the current index already is on the first zero padded octet
114: * - check it really is zero (overlapping bits) */
115: if (0 != result[out_pos]) return NULL;
116: break;
117: }
118:
119: buffer_commit(out, out_pos);
120:
121: return result;
122: }
123:
124: size_t li_to_base64_no_padding(char* out, size_t out_length, const unsigned char* in, size_t in_length, base64_charset charset) {
125: const size_t full_tuples = in_length / 3;
126: const size_t in_tuple_remainder = in_length % 3;
127: const size_t out_tuple_remainder = in_tuple_remainder ? 1 + in_tuple_remainder : 0;
128: const size_t require_space = 4 * full_tuples + out_tuple_remainder;
129: const char* base64_table;
130: size_t i;
131: size_t out_pos = 0;
132:
133: switch (charset) {
134: case BASE64_STANDARD:
135: base64_table = base64_standard_table;
136: break;
137: case BASE64_URL:
138: base64_table = base64_url_table;
139: break;
140: default:
141: force_assert(0 && "invalid charset");
142: }
143:
144: /* check overflows */
145: force_assert(full_tuples <= 2*full_tuples);
146: force_assert(full_tuples <= 4*full_tuples);
147: force_assert(4*full_tuples <= 4*full_tuples + out_tuple_remainder);
148: force_assert(require_space <= out_length);
149:
150: for (i = 2; i < in_length; i += 3) {
151: unsigned int v = (in[i-2] << 16) | (in[i-1] << 8) | in[i];
152: out[out_pos+3] = base64_table[v & 0x3f]; v >>= 6;
153: out[out_pos+2] = base64_table[v & 0x3f]; v >>= 6;
154: out[out_pos+1] = base64_table[v & 0x3f]; v >>= 6;
155: out[out_pos+0] = base64_table[v & 0x3f];
156: out_pos += 4;
157: }
158: switch (in_tuple_remainder) {
159: case 0:
160: break;
161: case 1:
162: {
163: /* pretend in[i-1] = in[i] = 0, don't write last two (out_pos+3, out_pos+2) characters */
164: unsigned int v = (in[i-2] << 4);
165: out[out_pos+1] = base64_table[v & 0x3f]; v >>= 6;
166: out[out_pos+0] = base64_table[v & 0x3f];
167: out_pos += 2;
168: }
169: break;
170: case 2:
171: {
172: /* pretend in[i] = 0, don't write last (out_pos+3) character */
173: unsigned int v = (in[i-2] << 10) | (in[i-1] << 2);
174: out[out_pos+2] = base64_table[v & 0x3f]; v >>= 6;
175: out[out_pos+1] = base64_table[v & 0x3f]; v >>= 6;
176: out[out_pos+0] = base64_table[v & 0x3f];
177: out_pos += 3;
178: }
179: break;
180: }
181: force_assert(out_pos <= out_length);
182: return out_pos;
183: }
184:
185: size_t li_to_base64(char* out, size_t out_length, const unsigned char* in, size_t in_length, base64_charset charset) {
186: const size_t in_tuple_remainder = in_length % 3;
187: size_t padding_length = in_tuple_remainder ? 3 - in_tuple_remainder : 0;
188:
189: char padding;
190: size_t out_pos;
191:
192: switch (charset) {
193: case BASE64_STANDARD:
194: padding = base64_standard_table[64];
195: break;
196: case BASE64_URL:
197: padding = base64_url_table[64];
198: break;
199: default:
200: force_assert(0 && "invalid charset");
201: }
202:
203: force_assert(out_length >= padding_length);
204: out_pos = li_to_base64_no_padding(out, out_length - padding_length, in, in_length, charset);
205:
206: while (padding_length > 0) {
207: out[out_pos++] = padding;
208: padding_length--;
209: }
210:
211: force_assert(out_pos <= out_length);
212:
213: return out_pos;
214: }
215:
216:
217: char* buffer_append_base64_encode_no_padding(buffer *out, const unsigned char* in, size_t in_length, base64_charset charset) {
218: size_t reserve = 4*(in_length/3) + 4;
219: char* result = buffer_string_prepare_append(out, reserve);
220: size_t out_pos = li_to_base64_no_padding(result, reserve, in, in_length, charset);
221:
222: buffer_commit(out, out_pos);
223:
224: return result;
225: }
226:
227: char* buffer_append_base64_encode(buffer *out, const unsigned char* in, size_t in_length, base64_charset charset) {
228: size_t reserve = 4*(in_length/3) + 4;
229: char* result = buffer_string_prepare_append(out, reserve);
230: size_t out_pos = li_to_base64(result, reserve, in, in_length, charset);
231:
232: buffer_commit(out, out_pos);
233:
234: return result;
235: }
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