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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* base64.c - RFC4648-compliant base64 encoding
*
* Copyright (c) 2020 Hannes Reinecke, SUSE
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
static const char base64_table[65] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
/**
* base64_encode() - base64-encode some bytes
* @src: the bytes to encode
* @srclen: number of bytes to encode
* @dst: (output) the base64-encoded string. Not NUL-terminated.
*
* Encodes the input string using characters from the set [A-Za-z0-9+,].
* The encoded string is roughly 4/3 times the size of the input string.
*
* Return: length of the encoded string
*/
int base64_encode(const unsigned char *src, int srclen, char *dst)
{
int i, bits = 0;
uint32_t ac = 0;
char *cp = dst;
for (i = 0; i < srclen; i++) {
ac = (ac << 8) | src[i];
bits += 8;
do {
bits -= 6;
*cp++ = base64_table[(ac >> bits) & 0x3f];
} while (bits >= 6);
}
if (bits) {
*cp++ = base64_table[(ac << (6 - bits)) & 0x3f];
bits -= 6;
}
while (bits < 0) {
*cp++ = '=';
bits += 2;
}
return cp - dst;
}
/**
* base64_decode() - base64-decode some bytes
* @src: the base64-encoded string to decode
* @len: number of bytes to decode
* @dst: (output) the decoded bytes.
*
* Decodes the base64-encoded bytes @src according to RFC 4648.
*
* Return: number of decoded bytes
*/
int base64_decode(const char *src, int srclen, unsigned char *dst)
{
uint32_t ac = 0;
int i, bits = 0;
unsigned char *bp = dst;
for (i = 0; i < srclen; i++) {
const char *p = strchr(base64_table, src[i]);
if (src[i] == '=') {
ac = (ac << 6);
bits += 6;
if (bits >= 8)
bits -= 8;
continue;
}
if (!p || !src[i])
return -EINVAL;
ac = (ac << 6) | (p - base64_table);
bits += 6;
if (bits >= 8) {
bits -= 8;
*bp++ = (unsigned char)(ac >> bits);
}
}
if (ac && ((1 << bits) - 1))
return -EAGAIN;
return bp - dst;
}
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