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/* Copyright (C) 2018 C. McEnroe <june@causal.agency>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <err.h>
#include <stdlib.h>
#include <string.h>
#include <sysexits.h>
#include "chat.h"
static const char Base64[64] = {
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
};
size_t base64Size(size_t len) {
return 1 + (len + 2) / 3 * 4;
}
void base64(char *dst, const byte *src, size_t len) {
size_t i = 0;
while (len > 2) {
dst[i++] = Base64[0x3F & (src[0] >> 2)];
dst[i++] = Base64[0x3F & (src[0] << 4 | src[1] >> 4)];
dst[i++] = Base64[0x3F & (src[1] << 2 | src[2] >> 6)];
dst[i++] = Base64[0x3F & src[2]];
src += 3;
len -= 3;
}
if (len) {
dst[i++] = Base64[0x3F & (src[0] >> 2)];
if (len > 1) {
dst[i++] = Base64[0x3F & (src[0] << 4 | src[1] >> 4)];
dst[i++] = Base64[0x3F & (src[1] << 2)];
} else {
dst[i++] = Base64[0x3F & (src[0] << 4)];
dst[i++] = '=';
}
dst[i++] = '=';
}
dst[i] = '\0';
}
#ifdef TEST
#include <assert.h>
int main() {
assert(5 == base64Size(1));
assert(5 == base64Size(2));
assert(5 == base64Size(3));
assert(9 == base64Size(4));
char b64[base64Size(3)];
assert((base64(b64, (byte *)"cat", 3), !strcmp("Y2F0", b64)));
assert((base64(b64, (byte *)"ca", 2), !strcmp("Y2E=", b64)));
assert((base64(b64, (byte *)"c", 1), !strcmp("Yw==", b64)));
assert((base64(b64, (byte *)"\xFF\x00\xFF", 3), !strcmp("/wD/", b64)));
assert((base64(b64, (byte *)"\x00\xFF\x00", 3), !strcmp("AP8A", b64)));
}
#endif
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