Adding support for passing custom config file for mbedTLS

mbed_app.json

@@ -13,6 +13,7 @@
             "value": "\"Password\""
         }
     },
+    "macros": ["MBEDTLS_USER_CONFIG_FILE=\"mbedtls_mbed_client_config.h\""],
     "target_overrides": {
         "*": {
             "target.features_add": ["CLIENT", "COMMON_PAL"],

mbedtls_mbed_client_config.h

@@ -0,0 +1,115 @@
+/*
+ *  Minimal configuration for using mbedtls as part of mbed-client
+ *
+ *  Copyright (C) 2006-2016, 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 MBEDTLS_CUSTOM_CONFIG_H
+#define MBEDTLS_CUSTOM_CONFIG_H
+
+/* System support */
+#define MBEDTLS_HAVE_ASM
+
+/* mbed TLS feature support */
+#define MBEDTLS_ECP_DP_SECP256R1_ENABLED
+#define MBEDTLS_ECP_NIST_OPTIM
+#define MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
+#define MBEDTLS_SSL_PROTO_TLS1_2
+#define MBEDTLS_SSL_PROTO_DTLS
+#define MBEDTLS_SSL_DTLS_ANTI_REPLAY
+#define MBEDTLS_SSL_DTLS_HELLO_VERIFY
+#define MBEDTLS_SSL_EXPORT_KEYS
+
+/* mbed TLS modules */
+#define MBEDTLS_AES_C
+#define MBEDTLS_ASN1_PARSE_C
+#define MBEDTLS_ASN1_WRITE_C
+#define MBEDTLS_BIGNUM_C
+#define MBEDTLS_CCM_C
+#define MBEDTLS_CIPHER_C
+#define MBEDTLS_CTR_DRBG_C
+#define MBEDTLS_ECP_C
+#define MBEDTLS_ENTROPY_C
+#define MBEDTLS_MD_C
+#define MBEDTLS_OID_C
+#define MBEDTLS_PK_C
+#define MBEDTLS_PK_PARSE_C
+#define MBEDTLS_SHA256_C
+#define MBEDTLS_SSL_COOKIE_C
+#define MBEDTLS_SSL_CLI_C
+#define MBEDTLS_SSL_SRV_C
+#define MBEDTLS_SSL_TLS_C
+
+// XXX mbedclient needs these: mbedtls_x509_crt_free, mbedtls_x509_crt_init, mbedtls_x509_crt_parse
+#define MBEDTLS_X509_USE_C
+#define MBEDTLS_X509_CRT_PARSE_C
+// a bit wrong way to get mbedtls_ssl_conf_psk:
+// XXX: this should be ifdef'd out from client too
+#define MBEDTLS_KEY_EXCHANGE__SOME__PSK_ENABLED
+
+// XXX: clean these up!!
+#define MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED
+#define MBEDTLS_KEY_EXCHANGE__SOME__ECDHE_ENABLED
+#define MBEDTLS_KEY_EXCHANGE_ECDHE_ECDSA_ENABLED
+#define MBEDTLS_SHA512_C
+#define MBEDTLS_ECDH_C
+#define MBEDTLS_GCM_C
+#define MBEDTLS_CCM_C
+
+#define MBEDTLS_PKCS1_V15
+
+#define MBEDTLS_CIPHER_MODE_CBC
+#define MBEDTLS_ECDH_C
+#define MBEDTLS_ECDSA_C
+#define MBEDTLS_X509_CRT_PARSE_C
+
+// Remove RSA, save 20KB at total
+#undef MBEDTLS_RSA_C
+#undef MBEDTLS_KEY_EXCHANGE_ECDHE_RSA_ENABLED
+
+// Remove error messages, save 10KB of ROM
+#undef MBEDTLS_ERROR_C
+
+// Remove selftesting and save 11KB of ROM
+#undef MBEDTLS_SELF_TEST
+
+#undef MBEDTLS_SSL_COOKIE_C
+
+// Reduces ROM size by 30 kB
+#undef MBEDTLS_ERROR_STRERROR_DUMMY
+#undef MBEDTLS_VERSION_FEATURES
+#undef MBEDTLS_DEBUG_C
+
+// needed for parsing the certificates
+#define MBEDTLS_PEM_PARSE_C
+// dep of the previous
+#define MBEDTLS_BASE64_C
+
+// reduce IO buffer to save RAM, default is 16KB
+#define MBEDTLS_SSL_MAX_CONTENT_LEN 2048
+
+// define to save 8KB RAM at the expense of ROM
+#undef MBEDTLS_AES_ROM_TABLES
+
+// Save ROM and a few bytes of RAM by specifying our own ciphersuite list
+#define MBEDTLS_SSL_CIPHERSUITES MBEDTLS_TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,MBEDTLS_TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256
+
+#include "mbedtls/check_config.h"
+
+#endif /* MBEDTLS_CUSTOM_CONFIG_H */