diff options
author | Hannes Reinecke | 2022-06-27 11:51:59 +0200 |
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committer | Jens Axboe | 2022-08-02 17:14:47 -0600 |
commit | a116e1cdc64a743c36c40e6fa639dec991c157a3 (patch) | |
tree | 06203e96d2cf80d2dec7b2a72c1e83acd08cfce2 /lib/base64.c | |
parent | 9e2f284e149124aa9a6b963882d2b39ae1742196 (diff) |
lib/base64: RFC4648-compliant base64 encoding
Add RFC4648-compliant base64 encoding and decoding routines, based on
the base64url encoding in fs/crypto/fname.c.
Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Cc: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'lib/base64.c')
-rw-r--r-- | lib/base64.c | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/lib/base64.c b/lib/base64.c new file mode 100644 index 000000000000..b736a7a431c5 --- /dev/null +++ b/lib/base64.c @@ -0,0 +1,103 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * base64.c - RFC4648-compliant base64 encoding + * + * Copyright (c) 2020 Hannes Reinecke, SUSE + * + * Based on the base64url routines from fs/crypto/fname.c + * (which are using the URL-safe base64 encoding), + * modified to use the standard coding table from RFC4648 section 4. + */ + +#include <linux/kernel.h> +#include <linux/types.h> +#include <linux/export.h> +#include <linux/string.h> +#include <linux/base64.h> + +static const char base64_table[65] = + "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; + +/** + * base64_encode() - base64-encode some binary data + * @src: the binary data to encode + * @srclen: the length of @src in bytes + * @dst: (output) the base64-encoded string. Not NUL-terminated. + * + * Encodes data using base64 encoding, i.e. the "Base 64 Encoding" specified + * by RFC 4648, including the '='-padding. + * + * Return: the length of the resulting base64-encoded string in bytes. + */ +int base64_encode(const u8 *src, int srclen, char *dst) +{ + u32 ac = 0; + int bits = 0; + int i; + 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; +} +EXPORT_SYMBOL_GPL(base64_encode); + +/** + * base64_decode() - base64-decode a string + * @src: the string to decode. Doesn't need to be NUL-terminated. + * @srclen: the length of @src in bytes + * @dst: (output) the decoded binary data + * + * Decodes a string using base64 encoding, i.e. the "Base 64 Encoding" + * specified by RFC 4648, including the '='-padding. + * + * This implementation hasn't been optimized for performance. + * + * Return: the length of the resulting decoded binary data in bytes, + * or -1 if the string isn't a valid base64 string. + */ +int base64_decode(const char *src, int srclen, u8 *dst) +{ + u32 ac = 0; + int bits = 0; + int i; + u8 *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 == NULL || src[i] == 0) + return -1; + ac = (ac << 6) | (p - base64_table); + bits += 6; + if (bits >= 8) { + bits -= 8; + *bp++ = (u8)(ac >> bits); + } + } + if (ac & ((1 << bits) - 1)) + return -1; + return bp - dst; +} +EXPORT_SYMBOL_GPL(base64_decode); |