CryptoCore class to access to base crypto utils.

Godot core needs MD5/SHA256/AES/Base64 which used to be provided by
separate libraries.
Since we bundle mbedtls in most cases, and we can easily only include
the needed sources if we so desire, let's use it.

To simplify library changes in the future, and better isolate header
dependencies all functions have been wrapped around inside a class in
`core/math/crypto_base.h`.

If the mbedtls module is disabled, we only bundle the needed source
files independently of the `builtin_mbedtls` option.
If the module is enabled, the `builtin_mbedtls` option works as usual.

Also remove some unused headers from StreamPeerMbedTLS which were
causing build issues.

3 files changed, 269 insertions, 1 deletions

diff --git a/core/math/SCsub b/core/math/SCsub
index 1c5f954470..4e76efceff 100644
--- a/core/math/SCsub
+++ b/core/math/SCsub
@@ -2,4 +2,37 @@
 
 Import('env')
 
-env.add_source_files(env.core_sources, "*.cpp")
+env_math = env.Clone() # Maybe make one specific for crypto?
+
+is_builtin = env["builtin_mbedtls"]
+has_module = env["module_mbedtls_enabled"]
+
+if is_builtin or not has_module:
+    # Use our headers for builtin or if the module is not going to be compiled.
+    # We decided not to depend on system mbedtls just for these few files that can
+    # be easily extracted.
+    env_math.Prepend(CPPPATH=["#thirdparty/mbedtls/include"])
+
+# MbedTLS core functions (for CryptoCore).
+# If the mbedtls module is compiled we don't need to add the .c files with our
+# custom config since they will be built by the module itself.
+# Only if the module is not enabled, we must compile here the required sources
+# to make a "light" build with only the necessary mbedtls files.
+if not has_module:
+    env_thirdparty = env_math.Clone()
+    env_thirdparty.disable_warnings()
+    # Custom config file
+    env_thirdparty.Append(CPPFLAGS=['-DMBEDTLS_CONFIG_FILE="\\"thirdparty/mbedtls/include/godot_core_mbedtls_config.h\\""'])
+    thirdparty_mbedtls_dir = "#thirdparty/mbedtls/library/"
+    thirdparty_mbedtls_sources = [
+        "aes.c",
+        "base64.c",
+        "md5.c",
+        "sha1.c",
+        "sha256.c",
+        "godot_core_mbedtls_platform.c"
+    ]
+    thirdparty_mbedtls_sources = [thirdparty_mbedtls_dir + file for file in thirdparty_mbedtls_sources]
+    env_thirdparty.add_source_files(env.core_sources, thirdparty_mbedtls_sources)
+
+env_math.add_source_files(env.core_sources, "*.cpp")
diff --git a/core/math/crypto_core.cpp b/core/math/crypto_core.cpp
new file mode 100644
index 0000000000..6449d94db8
--- /dev/null
+++ b/core/math/crypto_core.cpp
@@ -0,0 +1,146 @@
+/*************************************************************************/
+/*  crypto_core.cpp                                                      */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2019 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2019 Godot Engine contributors (cf. AUTHORS.md)    */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#include "crypto_core.h"
+
+#include <mbedtls/aes.h>
+#include <mbedtls/base64.h>
+#include <mbedtls/md5.h>
+#include <mbedtls/sha1.h>
+#include <mbedtls/sha256.h>
+
+// MD5
+CryptoCore::MD5Context::MD5Context() {
+	ctx = memalloc(sizeof(mbedtls_md5_context));
+	mbedtls_md5_init((mbedtls_md5_context *)ctx);
+}
+
+CryptoCore::MD5Context::~MD5Context() {
+	mbedtls_md5_free((mbedtls_md5_context *)ctx);
+	memfree((mbedtls_md5_context *)ctx);
+}
+
+Error CryptoCore::MD5Context::start() {
+	int ret = mbedtls_md5_starts_ret((mbedtls_md5_context *)ctx);
+	return ret ? FAILED : OK;
+}
+
+Error CryptoCore::MD5Context::update(uint8_t *p_src, size_t p_len) {
+	int ret = mbedtls_md5_update_ret((mbedtls_md5_context *)ctx, p_src, p_len);
+	return ret ? FAILED : OK;
+}
+
+Error CryptoCore::MD5Context::finish(unsigned char r_hash[16]) {
+	int ret = mbedtls_md5_finish_ret((mbedtls_md5_context *)ctx, r_hash);
+	return ret ? FAILED : OK;
+}
+
+// SHA256
+CryptoCore::SHA256Context::SHA256Context() {
+	ctx = memalloc(sizeof(mbedtls_sha256_context));
+	mbedtls_sha256_init((mbedtls_sha256_context *)ctx);
+}
+
+CryptoCore::SHA256Context::~SHA256Context() {
+	mbedtls_sha256_free((mbedtls_sha256_context *)ctx);
+	memfree((mbedtls_sha256_context *)ctx);
+}
+
+Error CryptoCore::SHA256Context::start() {
+	int ret = mbedtls_sha256_starts_ret((mbedtls_sha256_context *)ctx, 0);
+	return ret ? FAILED : OK;
+}
+
+Error CryptoCore::SHA256Context::update(uint8_t *p_src, size_t p_len) {
+	int ret = mbedtls_sha256_update_ret((mbedtls_sha256_context *)ctx, p_src, p_len);
+	return ret ? FAILED : OK;
+}
+
+Error CryptoCore::SHA256Context::finish(unsigned char r_hash[16]) {
+	int ret = mbedtls_sha256_finish_ret((mbedtls_sha256_context *)ctx, r_hash);
+	return ret ? FAILED : OK;
+}
+
+// AES256
+CryptoCore::AESContext::AESContext() {
+	ctx = memalloc(sizeof(mbedtls_aes_context));
+	mbedtls_aes_init((mbedtls_aes_context *)ctx);
+}
+
+CryptoCore::AESContext::~AESContext() {
+	mbedtls_aes_free((mbedtls_aes_context *)ctx);
+	memfree((mbedtls_aes_context *)ctx);
+}
+
+Error CryptoCore::AESContext::set_encode_key(const uint8_t *p_key, size_t p_bits) {
+	int ret = mbedtls_aes_setkey_enc((mbedtls_aes_context *)ctx, p_key, p_bits);
+	return ret ? FAILED : OK;
+}
+
+Error CryptoCore::AESContext::set_decode_key(const uint8_t *p_key, size_t p_bits) {
+	int ret = mbedtls_aes_setkey_dec((mbedtls_aes_context *)ctx, p_key, p_bits);
+	return ret ? FAILED : OK;
+}
+
+Error CryptoCore::AESContext::encrypt_ecb(const uint8_t p_src[16], uint8_t r_dst[16]) {
+	int ret = mbedtls_aes_crypt_ecb((mbedtls_aes_context *)ctx, MBEDTLS_AES_ENCRYPT, p_src, r_dst);
+	return ret ? FAILED : OK;
+}
+
+Error CryptoCore::AESContext::decrypt_ecb(const uint8_t p_src[16], uint8_t r_dst[16]) {
+	int ret = mbedtls_aes_crypt_ecb((mbedtls_aes_context *)ctx, MBEDTLS_AES_DECRYPT, p_src, r_dst);
+	return ret ? FAILED : OK;
+}
+
+// CryptoCore
+Error CryptoCore::b64_encode(uint8_t *r_dst, int p_dst_len, size_t *r_len, const uint8_t *p_src, int p_src_len) {
+	int ret = mbedtls_base64_encode(r_dst, p_dst_len, r_len, p_src, p_src_len);
+	return ret ? FAILED : OK;
+}
+
+Error CryptoCore::b64_decode(uint8_t *r_dst, int p_dst_len, size_t *r_len, const uint8_t *p_src, int p_src_len) {
+	int ret = mbedtls_base64_decode(r_dst, p_dst_len, r_len, p_src, p_src_len);
+	return ret ? FAILED : OK;
+}
+
+Error CryptoCore::md5(const uint8_t *p_src, int p_src_len, unsigned char r_hash[16]) {
+	int ret = mbedtls_md5_ret(p_src, p_src_len, r_hash);
+	return ret ? FAILED : OK;
+}
+
+Error CryptoCore::sha1(const uint8_t *p_src, int p_src_len, unsigned char r_hash[20]) {
+	int ret = mbedtls_sha1_ret(p_src, p_src_len, r_hash);
+	return ret ? FAILED : OK;
+}
+
+Error CryptoCore::sha256(const uint8_t *p_src, int p_src_len, unsigned char r_hash[32]) {
+	int ret = mbedtls_sha256_ret(p_src, p_src_len, r_hash, 0);
+	return ret ? FAILED : OK;
+}
diff --git a/core/math/crypto_core.h b/core/math/crypto_core.h
new file mode 100644
index 0000000000..1cb3c86e18
--- /dev/null
+++ b/core/math/crypto_core.h
@@ -0,0 +1,89 @@
+/*************************************************************************/
+/*  crypto_core.h                                                        */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2019 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2019 Godot Engine contributors (cf. AUTHORS.md)    */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#ifndef CRYPTO_CORE_H
+#define CRYPTO_CORE_H
+
+#include "core/reference.h"
+
+class CryptoCore {
+
+public:
+	class MD5Context {
+
+	private:
+		void *ctx; // To include, or not to include...
+
+	public:
+		MD5Context();
+		~MD5Context();
+
+		Error start();
+		Error update(uint8_t *p_src, size_t p_len);
+		Error finish(unsigned char r_hash[16]);
+	};
+
+	class SHA256Context {
+
+	private:
+		void *ctx; // To include, or not to include...
+
+	public:
+		SHA256Context();
+		~SHA256Context();
+
+		Error start();
+		Error update(uint8_t *p_src, size_t p_len);
+		Error finish(unsigned char r_hash[16]);
+	};
+
+	class AESContext {
+
+	private:
+		void *ctx; // To include, or not to include...
+
+	public:
+		AESContext();
+		~AESContext();
+
+		Error set_encode_key(const uint8_t *p_key, size_t p_bits);
+		Error set_decode_key(const uint8_t *p_key, size_t p_bits);
+		Error encrypt_ecb(const uint8_t p_src[16], uint8_t r_dst[16]);
+		Error decrypt_ecb(const uint8_t p_src[16], uint8_t r_dst[16]);
+	};
+
+	static Error b64_encode(uint8_t *r_dst, int p_dst_len, size_t *r_len, const uint8_t *p_src, int p_src_len);
+	static Error b64_decode(uint8_t *r_dst, int p_dst_len, size_t *r_len, const uint8_t *p_src, int p_src_len);
+
+	static Error md5(const uint8_t *p_src, int p_src_len, unsigned char r_hash[16]);
+	static Error sha1(const uint8_t *p_src, int p_src_len, unsigned char r_hash[20]);
+	static Error sha256(const uint8_t *p_src, int p_src_len, unsigned char r_hash[32]);
+};
+#endif // CRYPTO_CORE_H