copy base64 implementation from mbedtls

Using mbedtls commit f9c599cd8ac9d00c484d4f5b027e18c6af4f9fdf before
they re-licensed to Apache 2.0, so we have a GPL-v2-or-later bsae64
implementation and avoid having code under a different license in the
tree.

This code is the unmodified import, so we can record any local changes
compared to the original version.

Change-Id: I39a9d3ab98257d21b9439b00528c744efa372c14

1 files changed, 86 insertions, 0 deletions

diff --git a/include/osmocom/core/base64.h b/include/osmocom/core/base64.h
new file mode 100644
index 00000000..0f7233d2
--- /dev/null
+++ b/include/osmocom/core/base64.h
@@ -0,0 +1,86 @@
+/**
+ * \file base64.h
+ *
+ * \brief RFC 1521 base64 encoding/decoding
+ *
+ *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
+ *
+ *  This file is part of mbed TLS (https://tls.mbed.org)
+ *
+ *  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.
+ */
+#ifndef MBEDTLS_BASE64_H
+#define MBEDTLS_BASE64_H
+
+#include <stddef.h>
+
+#define MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL               -0x002A  /**< Output buffer too small. */
+#define MBEDTLS_ERR_BASE64_INVALID_CHARACTER              -0x002C  /**< Invalid character in input. */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * \brief          Encode a buffer into base64 format
+ *
+ * \param dst      destination buffer
+ * \param dlen     size of the destination buffer
+ * \param olen     number of bytes written
+ * \param src      source buffer
+ * \param slen     amount of data to be encoded
+ *
+ * \return         0 if successful, or MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL.
+ *                 *olen is always updated to reflect the amount
+ *                 of data that has (or would have) been written.
+ *
+ * \note           Call this function with dlen = 0 to obtain the
+ *                 required buffer size in *olen
+ */
+int mbedtls_base64_encode( unsigned char *dst, size_t dlen, size_t *olen,
+                   const unsigned char *src, size_t slen );
+
+/**
+ * \brief          Decode a base64-formatted buffer
+ *
+ * \param dst      destination buffer (can be NULL for checking size)
+ * \param dlen     size of the destination buffer
+ * \param olen     number of bytes written
+ * \param src      source buffer
+ * \param slen     amount of data to be decoded
+ *
+ * \return         0 if successful, MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL, or
+ *                 MBEDTLS_ERR_BASE64_INVALID_CHARACTER if the input data is
+ *                 not correct. *olen is always updated to reflect the amount
+ *                 of data that has (or would have) been written.
+ *
+ * \note           Call this function with *dst = NULL or dlen = 0 to obtain
+ *                 the required buffer size in *olen
+ */
+int mbedtls_base64_decode( unsigned char *dst, size_t dlen, size_t *olen,
+                   const unsigned char *src, size_t slen );
+
+/**
+ * \brief          Checkup routine
+ *
+ * \return         0 if successful, or 1 if the test failed
+ */
+int mbedtls_base64_self_test( int verbose );
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* base64.h */