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Diffstat (limited to 'util/base64.c')
-rw-r--r-- | util/base64.c | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/util/base64.c b/util/base64.c new file mode 100644 index 0000000..7f47cda --- /dev/null +++ b/util/base64.c @@ -0,0 +1,107 @@ +// 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 <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; + u_int32_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) +{ + u_int32_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; +} |