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#include "base64.h"
#include "str.h"
static char *b64alpha = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
#define B64PAD '='
/* returns 0 ok, 1 illegal, -1 problem */
int b64decode(const unsigned char *in, int l, stralloc *out)
/* stralloc *out => not null terminated */
{
int p = 0;
int n;
unsigned int x;
int i, j;
char *s;
unsigned char b[3];
if (l == 0) {
if (!stralloc_copys(out, "")) return -1;
return 0;
}
while (in[l - 1] == B64PAD) {
p++;
l--;
}
n = (l + p) / 4;
i = (n * 3) - p;
if (!stralloc_ready(out, i)) return -1;
out->len = i;
s = out->s;
for (i = 0; i < n - 1; i++) {
x = 0;
for (j = 0; j < 4; j++) {
if (in[j] >= 'A' && in[j] <= 'Z')
x = (x << 6) + (unsigned int)(in[j] - 'A' + 0);
else if (in[j] >= 'a' && in[j] <= 'z')
x = (x << 6) + (unsigned int)(in[j] - 'a' + 26);
else if (in[j] >= '0' && in[j] <= '9')
x = (x << 6) + (unsigned int)(in[j] - '0' + 52);
else if (in[j] == '+')
x = (x << 6) + 62;
else if (in[j] == '/')
x = (x << 6) + 63;
else if (in[j] == '=')
x = (x << 6);
else
return 1;
}
s[2] = (unsigned char)(x & 255);
x >>= 8;
s[1] = (unsigned char)(x & 255);
x >>= 8;
s[0] = (unsigned char)(x & 255);
x >>= 8;
s += 3;
in += 4;
}
x = 0;
for (j = 0; j < 4; j++) {
if (in[j] >= 'A' && in[j] <= 'Z')
x = (x << 6) + (unsigned int)(in[j] - 'A' + 0);
else if (in[j] >= 'a' && in[j] <= 'z')
x = (x << 6) + (unsigned int)(in[j] - 'a' + 26);
else if (in[j] >= '0' && in[j] <= '9')
x = (x << 6) + (unsigned int)(in[j] - '0' + 52);
else if (in[j] == '+')
x = (x << 6) + 62;
else if (in[j] == '/')
x = (x << 6) + 63;
else if (in[j] == '=')
x = (x << 6);
else
return 1;
}
b[2] = (unsigned char)(x & 255);
x >>= 8;
b[1] = (unsigned char)(x & 255);
x >>= 8;
b[0] = (unsigned char)(x & 255);
x >>= 8;
for (i = 0; i < 3 - p; i++) s[i] = b[i];
return 0;
}
int b64encode(stralloc *in, stralloc *out)
{
unsigned char a, b, c;
int i;
char *s;
if (in->len == 0) {
if (!stralloc_copys(out, "")) return -1;
return 0;
}
i = in->len / 3 * 4 + 4;
if (!stralloc_ready(out, i)) return -1;
s = out->s;
for (i = 0; i < in->len; i += 3) {
a = in->s[i];
b = i + 1 < in->len ? in->s[i + 1] : 0;
c = i + 2 < in->len ? in->s[i + 2] : 0;
*s++ = b64alpha[a >> 2];
*s++ = b64alpha[((a & 3) << 4) | (b >> 4)];
if (i + 1 >= in->len)
*s++ = B64PAD;
else
*s++ = b64alpha[((b & 0x0f) << 2) | (c >> 6)];
if (i + 2 >= in->len)
*s++ = B64PAD;
else
*s++ = b64alpha[c & 0x3f];
}
out->len = s - out->s;
return 0;
}
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