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[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
14 static const signed char base64_standard_reverse_table[] = {
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[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_=";
28 static const signed char base64_url_reverse_table[] = {
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, -1, -1, /* 0x20 - 0x2F */
33 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -3, -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
li_base64_dec(unsigned char * const result,const size_t out_length,const char * const in,const size_t in_length,const base64_charset charset)40 size_t li_base64_dec(unsigned char * const result, const size_t out_length, const char * const in, const size_t in_length, const base64_charset charset) {
41 const unsigned char *un = (const unsigned char *)in;
42 const unsigned char * const end = un + in_length;
43 const signed char * const base64_reverse_table = (charset)
44 ? base64_url_reverse_table /* BASE64_URL */
45 : base64_standard_reverse_table; /* BASE64_STANDARD */
46
47 int_fast32_t ch = 0;
48 int_fast32_t out4 = 0;
49 size_t i = 0;
50 size_t out_pos = 0;
51 for (; un < end; ++un) {
52 ch = (*un < 128) ? base64_reverse_table[*un] : -1;
53 if (__builtin_expect( (ch < 0), 0)) {
54 /* skip formatted base64; skip whitespace ('\r' '\n' '\t' ' ')*/
55 if (-2 == ch) /*(loose check; skip ' ', all ctrls not \127 or \0)*/
56 continue; /* skip character */
57 break;
58 }
59
60 out4 = (out4 << 6) | ch;
61 if ((++i & 3) == 0) {
62 result[out_pos] = (out4 >> 16) & 0xFF;
63 result[out_pos+1] = (out4 >> 8) & 0xFF;
64 result[out_pos+2] = (out4 ) & 0xFF;
65 out_pos += 3;
66 out4 = 0;
67 }
68 }
69
70 /* permit base64 string ending with pad chars (ch == -3); not checking
71 * for one or two pad chars + optional whitespace reaches in_length) */
72 /* permit base64 string truncated before in_length (*un == '\0') */
73 switch (un == end || ch == -3 || *un != '\0' ? (i & 3) : 1) {
74 case 3:
75 result[out_pos++] = (out4 >> 10);
76 out4 <<= 2;
77 __attribute_fallthrough__
78 case 2:
79 result[out_pos++] = (out4 >> 4) & 0xFF;
80 __attribute_fallthrough__
81 case 0:
82 force_assert(out_pos <= out_length);
83 return out_pos;
84 case 1: /* pad char or str end can only come after 2+ base64 chars */
85 default:
86 return 0; /* invalid character, abort */
87 }
88 }
89
li_base64_enc(char * const restrict out,const size_t out_length,const unsigned char * const restrict in,const size_t in_length,const base64_charset charset,const int pad)90 size_t li_base64_enc(char * const restrict out, const size_t out_length, const unsigned char * const restrict in, const size_t in_length, const base64_charset charset, const int pad) {
91 size_t i;
92 size_t out_pos = 0;
93 uint_fast32_t v;
94 const char* const base64_table = (charset)
95 ? base64_url_table /* BASE64_URL */
96 : base64_standard_table; /* BASE64_STANDARD */
97 const char padchar = base64_table[64]; /* padding char */
98
99 /* check overflows */
100 /* 1073741823 is max num full_tuples to avoid overflow in uint32_t;
101 * and (1 GB - 1) is ridiculously large for base64-encoded data */
102 force_assert(in_length <= 3221225469); /* (3221225469+2) / 3 * 4 < UINT32_MAX */
103 force_assert((in_length+2)/3*4 <= out_length);
104
105 for (i = 2; i < in_length; i += 3) {
106 v = (in[i-2] << 16) | (in[i-1] << 8) | in[i];
107 out[out_pos+0] = base64_table[(v >> 18) & 0x3f];
108 out[out_pos+1] = base64_table[(v >> 12) & 0x3f];
109 out[out_pos+2] = base64_table[(v >> 6) & 0x3f];
110 out[out_pos+3] = base64_table[(v ) & 0x3f];
111 out_pos += 4;
112 }
113
114 switch (in_length - (i-2)) {
115 case 0:
116 default:
117 break;
118 case 1:
119 {
120 /* pretend in[i-1] = in[i] = 0, don't write last two (out_pos+3, out_pos+2) characters */
121 v = (in[i-2] << 4);
122 out[out_pos+0] = base64_table[(v >> 6) & 0x3f];
123 out[out_pos+1] = base64_table[(v ) & 0x3f];
124 if (pad) {
125 out[out_pos+2] = out[out_pos+3] = padchar;
126 out_pos += 4;
127 }
128 else
129 out_pos += 2;
130 }
131 break;
132 case 2:
133 {
134 /* pretend in[i] = 0, don't write last (out_pos+3) character */
135 v = (in[i-2] << 10) | (in[i-1] << 2);
136 out[out_pos+0] = base64_table[(v >> 12) & 0x3f];
137 out[out_pos+1] = base64_table[(v >> 6) & 0x3f];
138 out[out_pos+2] = base64_table[(v ) & 0x3f];
139 if (pad) {
140 out[out_pos+3] = padchar;
141 out_pos += 4;
142 }
143 else
144 out_pos += 3;
145 }
146 break;
147 }
148
149 return out_pos;
150 }
151
152
buffer_append_base64_enc(buffer * out,const unsigned char * in,size_t in_length,base64_charset charset,int pad)153 char* buffer_append_base64_enc(buffer *out, const unsigned char* in, size_t in_length, base64_charset charset, int pad) {
154 const size_t reserve = (in_length+2)/3*4;
155 char * const result = buffer_string_prepare_append(out, reserve);
156 const size_t out_pos =
157 li_base64_enc(result, reserve, in, in_length, charset, pad);
158
159 buffer_commit(out, out_pos);
160
161 return result;
162 }
163
164
buffer_append_base64_decode(buffer * out,const char * in,size_t in_length,base64_charset charset)165 unsigned char* buffer_append_base64_decode(buffer *out, const char* in, size_t in_length, base64_charset charset) {
166 const size_t reserve = 3*(in_length/4) + 3;
167 unsigned char * const result = (unsigned char *)
168 buffer_string_prepare_append(out, reserve);
169 const size_t out_pos =
170 li_base64_dec(result, reserve, in, in_length, charset);
171
172 buffer_commit(out, out_pos);
173
174 return (out_pos || !in_length) ? result : NULL;
175 }
176