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base64.c
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base64.c
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#include "dnssec.h"
void
base64_encode(char *dst, const unsigned char *src, size_t len)
{
static const char b64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
for (size_t i = 0; i < len; i += 3, dst += 4) {
unsigned long x = (unsigned long)src[i] << 16;
dst[3] = i + 2 >= len ? '=' : b64[(x |= src[i + 2]) & 0x3f];
dst[2] = i + 1 >= len ? '=' : b64[(x |= (unsigned long)src[i + 1] << 8) >> 6 & 0x3f];
dst[1] = b64[x >> 12 & 0x3f];
dst[0] = b64[x >> 18];
}
*dst = '\0';
}
size_t
base64_decode(unsigned char *dst, const char *src)
{
static const char b64[] = {
['A'] = 0, ['B'] = 1, ['C'] = 2, ['D'] = 3,
['E'] = 4, ['F'] = 5, ['G'] = 6, ['H'] = 7,
['I'] = 8, ['J'] = 9, ['K'] = 10, ['L'] = 11,
['M'] = 12, ['N'] = 13, ['O'] = 14, ['P'] = 15,
['Q'] = 16, ['R'] = 17, ['S'] = 18, ['T'] = 19,
['U'] = 20, ['V'] = 21, ['W'] = 22, ['X'] = 23,
['Y'] = 24, ['Z'] = 25, ['a'] = 26, ['b'] = 27,
['c'] = 28, ['d'] = 29, ['e'] = 30, ['f'] = 31,
['g'] = 32, ['h'] = 33, ['i'] = 34, ['j'] = 35,
['k'] = 36, ['l'] = 37, ['m'] = 38, ['n'] = 39,
['o'] = 40, ['p'] = 41, ['q'] = 42, ['r'] = 43,
['s'] = 44, ['t'] = 45, ['u'] = 46, ['v'] = 47,
['w'] = 48, ['x'] = 49, ['y'] = 50, ['z'] = 51,
['0'] = 52, 53, 54, 55, 56, 57, 58, 59, 60, 61,
['+'] = 62, ['/'] = 63, ['='] = 0,
};
unsigned long x;
size_t i, len;
unsigned c, pad = 0;
for (i = 0, x = 0, len = 0; src[i]; ++i) {
c = src[i];
if (c == '=' && (!src[i + 1] || (src[i + 1] == '=' && !src[i + 2])))
++pad;
else if (c >= sizeof(b64) || (!b64[c] && c != 'A'))
return 0;
x = x << 6 | b64[c];
if (i % 4 == 3) {
dst[len + 2] = x & 0xff; x >>= 8;
dst[len + 1] = x & 0xff; x >>= 8;
dst[len + 0] = x & 0xff;
len += 3;
}
}
if (i % 4 != 0)
return 0;
return len - pad;
}