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#include "base64.h"
#include "stralloc.h"
#include "substdio.h"
#include "str.h"
static char *b64alpha =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
#define B64PAD '='
/* returns 0 ok, 1 illegal, -1 problem */
int b64decode(in,l,out)
const unsigned char *in;
int l;
stralloc *out; /* not null terminated */
{
int i, j;
unsigned char a[4];
unsigned char b[3];
char *s;
if (l == 0)
{
if (!stralloc_copys(out,"")) return -1;
return 0;
}
if (!stralloc_ready(out,l + 2)) return -1; /* XXX generous */
s = out->s;
for (i = 0;i < l;i += 4) {
for (j = 0;j < 4;j++)
if ((i + j) < l && in[i + j] != B64PAD)
{
a[j] = str_chr(b64alpha,in[i + j]);
if (a[j] > 63) return 1;
}
else a[j] = 0;
b[0] = (a[0] << 2) | (a[1] >> 4);
b[1] = (a[1] << 4) | (a[2] >> 2);
b[2] = (a[2] << 6) | (a[3]);
*s++ = b[0];
if (in[i + 1] == B64PAD) break;
*s++ = b[1];
if (in[i + 2] == B64PAD) break;
*s++ = b[2];
}
out->len = s - out->s;
while (out->len && !out->s[out->len - 1]) --out->len; /* XXX avoid? */
return 0;
}
int b64encode(in,out)
stralloc *in;
stralloc *out; /* not null terminated */
{
unsigned char a, b, c;
int i;
char *s;
if (in->len == 0)
{
if (!stralloc_copys(out,"")) return -1;
return 0;
}
if (!stralloc_ready(out,in->len / 3 * 4 + 4)) 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 & 15) << 2) | (c >> 6)];
if (i + 2 >= in->len) *s++ = B64PAD;
else *s++ = b64alpha[c & 63];
}
out->len = s - out->s;
return 0;
}
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