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/* copyright (c) 2022 - 2023 grunfink / MIT license */
#ifndef _XS_ENCDEC_H
#define _XS_ENCDEC_H
xs_str *xs_base64_enc(const xs_val *data, int sz);
xs_val *xs_base64_dec(const xs_str *data, int *size);
int xs_is_base64(const char *str);
#ifdef XS_IMPLEMENTATION
/** base64 */
static char *xs_b64_tbl = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz"
"0123456789+/=";
xs_str *xs_base64_enc_tbl(const xs_val *data, int sz, const char *b64_tbl)
/* encodes data to base64 using a table */
{
xs_str *s;
unsigned char *p;
char *i;
int bsz, n;
bsz = ((sz + 3 - 1) / 3) * 4;
i = s = xs_realloc(NULL, _xs_blk_size(bsz + 1));
p = (unsigned char *)data;
for (n = 0; n < sz; n += 3) {
int l = sz - n;
if (l == 1) {
*i++ = b64_tbl[(p[n] >> 2) & 0x3f];
*i++ = b64_tbl[(p[n] << 4) & 0x3f];
*i++ = '=';
*i++ = '=';
}
else
if (l == 2) {
*i++ = b64_tbl[(p[n] >> 2) & 0x3f];
*i++ = b64_tbl[(p[n] << 4 | p[n + 1] >> 4) & 0x3f];
*i++ = b64_tbl[(p[n + 1] << 2) & 0x3f];
*i++ = '=';
}
else {
*i++ = b64_tbl[(p[n] >> 2) & 0x3f];
*i++ = b64_tbl[(p[n] << 4 | p[n + 1] >> 4) & 0x3f];
*i++ = b64_tbl[(p[n + 1] << 2 | p[n + 2] >> 6) & 0x3f];
*i++ = b64_tbl[(p[n + 2]) & 0x3f];
}
}
*i = '\0';
return s;
}
xs_str *xs_base64_enc(const xs_val *data, int sz)
/* encodes data to base64 */
{
return xs_base64_enc_tbl(data, sz, xs_b64_tbl);
}
xs_val *xs_base64_dec_tbl(const xs_str *data, int *size, const char *b64_tbl)
/* decodes data from base64 using a table */
{
xs_val *s = NULL;
int sz = 0;
char *p;
p = (char *)data;
/* size of data must be a multiple of 4 */
if (strlen(p) % 4)
return NULL;
for (p = (char *)data; *p; p += 4) {
int cs[4];
int n;
unsigned char tmp[3];
for (n = 0; n < 4; n++) {
char *ss = strchr(b64_tbl, p[n]);
if (ss == NULL) {
/* not a base64 char */
return xs_free(s);
}
cs[n] = ss - b64_tbl;
}
n = 0;
/* first byte */
tmp[n++] = cs[0] << 2 | ((cs[1] >> 4) & 0x0f);
/* second byte */
if (cs[2] != 64)
tmp[n++] = cs[1] << 4 | ((cs[2] >> 2) & 0x3f);
/* third byte */
if (cs[3] != 64)
tmp[n++] = cs[2] << 6 | (cs[3] & 0x3f);
/* must be done manually because data can be pure binary */
s = xs_realloc(s, _xs_blk_size(sz + n));
memcpy(s + sz, tmp, n);
sz += n;
}
/* asciiz it to use it as a string */
s = xs_realloc(s, _xs_blk_size(sz + 1));
s[sz] = '\0';
*size = sz;
return s;
}
xs_val *xs_base64_dec(const xs_str *data, int *size)
/* decodes data from base64 */
{
return xs_base64_dec_tbl(data, size, xs_b64_tbl);
}
int xs_is_base64_tbl(const char *str, const char *b64_tbl)
/* returns 1 if str is a base64 string, with table */
{
while (*str) {
if (strchr(b64_tbl, *str++) == NULL)
return 0;
}
return 1;
}
int xs_is_base64(const char *str)
/* returns 1 if str is a base64 string */
{
return xs_is_base64_tbl(str, xs_b64_tbl);
}
#endif /* XS_IMPLEMENTATION */
#endif /* _XS_ENCDEC_H */
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