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
diff --git a/include/osmocom/core/base64.h b/include/osmocom/core/base64.h
new file mode 100644
index 0000000..0f7233d
--- /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 */