asio: Use internal ssl context and engine impl

Implement asio-ssl layer with three classes in asio::ssl::mbedtls:
* context -- replaces SSL_CTX, used mainly as a container to options,
certs, keys
* engine -- replaces SSL, implements the actual mbedtls operations
* bio -- implements openssl BIO specifically tailered to mbedtls and
its asio usage

Further updates:
* asio: Used shared_ptr<> for bio pairs
* asio: Add error checks to mbedtls-bio
* asio: Address potential ssl-context ownership issue
* asio: Address potential bio-engine ownership issue


* Original commit: espressif/esp-idf@d823106aa6

components/asio/port/mbedtls/src/mbedtls_context.cpp

@@ -0,0 +1,115 @@
+//
+// SPDX-FileCopyrightText: 2005 Voipster / Indrek dot Juhani at voipster dot com
+// SPDX-FileCopyrightText: 2005-2019 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// SPDX-License-Identifier: BSL-1.0
+//
+// SPDX-FileContributor: 2021 Espressif Systems (Shanghai) CO LTD
+//
+
+#include "asio/detail/config.hpp"
+#include "openssl_stub.hpp"
+#include <cstring>
+#include "asio/detail/throw_error.hpp"
+#include "asio/error.hpp"
+#include "asio/ssl/context.hpp"
+#include "asio/ssl/error.hpp"
+#include "mbedtls_context.hpp"
+
+
+namespace asio {
+namespace ssl {
+
+
+context::context(context::method m)
+        : handle_(0)
+{
+    handle_ = mbedtls::shared_ctx::create("mbedtls-context", m);
+    set_options(no_compression);
+}
+
+context::context(context&& other)
+{
+    handle_ = other.handle_;
+    other.handle_ = 0;
+}
+
+context& context::operator=(context&& other)
+{
+    context tmp(ASIO_MOVE_CAST(context)(*this));
+    handle_ = other.handle_;
+    other.handle_ = 0;
+    return *this;
+}
+
+context::~context()
+{
+    delete handle_;
+}
+
+context::native_handle_type context::native_handle()
+{
+    return handle_;
+}
+
+void context::set_options(context::options o)
+{
+    asio::error_code ec;
+    set_options(o, ec);
+    asio::detail::throw_error(ec, "set_options");
+}
+
+ASIO_SYNC_OP_VOID context::set_options(
+        context::options o, asio::error_code& ec)
+{
+    handle_->get()->options_ = o;
+    ec = asio::error_code();
+    ASIO_SYNC_OP_VOID_RETURN(ec);
+}
+
+void context::add_certificate_authority(const const_buffer& ca)
+{
+    asio::error_code ec;
+    add_certificate_authority(ca, ec);
+    asio::detail::throw_error(ec, "add_certificate_authority");
+}
+
+ASIO_SYNC_OP_VOID context::add_certificate_authority(
+        const const_buffer& ca, asio::error_code& ec)
+{
+    handle_->get()->ca_cert_ = ca;
+    ASIO_SYNC_OP_VOID_RETURN(asio::error_code());
+}
+
+void context::use_certificate_chain(const const_buffer& chain)
+{
+    asio::error_code ec;
+    use_certificate_chain(chain, ec);
+    asio::detail::throw_error(ec, "use_certificate_chain");
+}
+
+ASIO_SYNC_OP_VOID context::use_certificate_chain(
+        const const_buffer& chain, asio::error_code& ec)
+{
+    handle_->get()->cert_chain_ = chain;
+    ASIO_SYNC_OP_VOID_RETURN(asio::error_code());
+}
+
+void context::use_private_key(
+        const const_buffer& private_key, context::file_format format)
+{
+    asio::error_code ec;
+    use_private_key(private_key, format, ec);
+    asio::detail::throw_error(ec, "use_private_key");
+}
+
+ASIO_SYNC_OP_VOID context::use_private_key(
+        const const_buffer& private_key, context::file_format format,
+        asio::error_code& ec)
+{
+    handle_->get()->private_key_ = private_key;
+    ASIO_SYNC_OP_VOID_RETURN(asio::error_code());
+}
+
+} // namespace ssl
+} // namespace asio