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/configs/config-ccm-psk-tls1_2.h

@@ -0,0 +1,88 @@
+/**
+ * \file config-ccm-psk-tls1_2.h
+ *
+ * \brief Minimal configuration for TLS 1.2 with PSK and AES-CCM ciphersuites
+ */
+/*
+ *  Copyright (C) 2006-2015, 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)
+ */
+/*
+ * Minimal configuration for TLS 1.2 with PSK and AES-CCM ciphersuites
+ * Distinguishing features:
+ * - no bignum, no PK, no X509
+ * - fully modern and secure (provided the pre-shared keys have high entropy)
+ * - very low record overhead with CCM-8
+ * - optimized for low RAM usage
+ *
+ * See README.txt for usage instructions.
+ */
+#ifndef MBEDTLS_CONFIG_H
+#define MBEDTLS_CONFIG_H
+
+/* System support */
+//#define MBEDTLS_HAVE_TIME /* Optionally used in Hello messages */
+/* Other MBEDTLS_HAVE_XXX flags irrelevant for this configuration */
+
+/* mbed TLS feature support */
+#define MBEDTLS_KEY_EXCHANGE_PSK_ENABLED
+#define MBEDTLS_SSL_PROTO_TLS1_2
+
+/* mbed TLS modules */
+#define MBEDTLS_AES_C
+#define MBEDTLS_CCM_C
+#define MBEDTLS_CIPHER_C
+#define MBEDTLS_CTR_DRBG_C
+#define MBEDTLS_ENTROPY_C
+#define MBEDTLS_MD_C
+#define MBEDTLS_NET_C
+#define MBEDTLS_SHA256_C
+#define MBEDTLS_SSL_CLI_C
+#define MBEDTLS_SSL_SRV_C
+#define MBEDTLS_SSL_TLS_C
+
+/* Save RAM at the expense of ROM */
+#define MBEDTLS_AES_ROM_TABLES
+
+/* Save some RAM by adjusting to your exact needs */
+#define MBEDTLS_PSK_MAX_LEN    16 /* 128-bits keys are generally enough */
+
+/*
+ * You should adjust this to the exact number of sources you're using: default
+ * is the "platform_entropy_poll" source, but you may want to add other ones
+ * Minimum is 2 for the entropy test suite.
+ */
+#define MBEDTLS_ENTROPY_MAX_SOURCES 2
+
+/*
+ * Use only CCM_8 ciphersuites, and
+ * save ROM and a few bytes of RAM by specifying our own ciphersuite list
+ */
+#define MBEDTLS_SSL_CIPHERSUITES                        \
+        MBEDTLS_TLS_PSK_WITH_AES_256_CCM_8,             \
+        MBEDTLS_TLS_PSK_WITH_AES_128_CCM_8
+
+/*
+ * Save RAM at the expense of interoperability: do this only if you control
+ * both ends of the connection!  (See comments in "mbedtls/ssl.h".)
+ * The optimal size here depends on the typical size of records.
+ */
+#define MBEDTLS_SSL_MAX_CONTENT_LEN             1024
+
+#include "mbedtls/check_config.h"
+
+#endif /* MBEDTLS_CONFIG_H */