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-rw-r--r--util/base64.c105
1 files changed, 105 insertions, 0 deletions
diff --git a/util/base64.c b/util/base64.c
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+/*
+ * 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>
+
+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 == NULL || src[i] == 0)
+ 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;
+}