Feature/mbedtls (#84)

* try to import mbedtls and build it

* add stubs socket class

* some boilterplate, read and write function implemented

* more boilterplate / current error in handshake because no CA cert is setup

* add something so skip ca verification, can ws curl https://google.com !

* cleanup / close implemented

* tweak CMakefiles

* typo in include

* update readme

* disable unittests

third_party/mbedtls/crypto/library/psa_crypto_slot_management.h

@@ -0,0 +1,58 @@
+/*
+ *  PSA crypto layer on top of Mbed TLS crypto
+ */
+/*  Copyright (C) 2018, ARM Limited, All Rights Reserved
+ *  SPDX-License-Identifier: Apache-2.0
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License"); you may
+ *  not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ *  This file is part of mbed TLS (https://tls.mbed.org)
+ */
+
+#ifndef PSA_CRYPTO_SLOT_MANAGEMENT_H
+#define PSA_CRYPTO_SLOT_MANAGEMENT_H
+
+/* Number of key slots (plus one because 0 is not used).
+ * The value is a compile-time constant for now, for simplicity. */
+#define PSA_KEY_SLOT_COUNT 32
+
+/** Access a key slot at the given handle.
+ *
+ * \param handle        Key handle to query.
+ * \param[out] p_slot   On success, `*p_slot` contains a pointer to the
+ *                      key slot in memory designated by \p handle.
+ *
+ * \retval PSA_SUCCESS
+ *         Success: \p handle is a handle to `*p_slot`. Note that `*p_slot`
+ *         may be empty or occupied.
+ * \retval PSA_ERROR_INVALID_HANDLE
+ *         \p handle is out of range or is not in use.
+ * \retval PSA_ERROR_BAD_STATE
+ *         The library has not been initialized.
+ */
+psa_status_t psa_get_key_slot( psa_key_handle_t handle,
+                               psa_key_slot_t **p_slot );
+
+/** Initialize the key slot structures.
+ *
+ * \retval PSA_SUCCESS
+ *         Currently this function always succeeds.
+ */
+psa_status_t psa_initialize_key_slots( void );
+
+/** Delete all data from key slots in memory.
+ *
+ * This does not affect persistent storage. */
+void psa_wipe_all_key_slots( void );
+
+#endif /* PSA_CRYPTO_SLOT_MANAGEMENT_H */