mbed TLS client & server support (WIP)

CMakeLists.txt

@@ -13,3 +13,7 @@ set(COMPONENT_REQUIRES
 register_component()
 
 target_compile_options(${COMPONENT_TARGET} PRIVATE -fno-rtti)
+
+if(CONFIG_ASYNC_TCP_SSL_ENABLED)
+    target_compile_options(${COMPONENT_TARGET} PRIVATE -DASYNC_TCP_SSL_ENABLED)
+endif()

Kconfig.projbuild

@@ -27,4 +27,10 @@ config ASYNC_TCP_USE_WDT
     help
         Enable WDT for the AsyncTCP task, so it will trigger if a handler is locking the thread.
 
+config ASYNC_TCP_SSL_ENABLED
+    bool "Enable SSL for AsyncTCP client"
+    default "n"
+    help
+        Enables mbedTLS support for AsyncTCP clients.
+
 endmenu

README.md

@@ -11,3 +11,10 @@ This library is the base for [ESPAsyncWebServer](https://github.com/me-no-dev/ES
 
 ## AsyncClient and AsyncServer
 The base classes on which everything else is built. They expose all possible scenarios, but are really raw and require more skills to use.
+
+## TLS support
+Support for TLS is added using mbed TLS, for now only the client part is supported. You can enable this by adding the flag ASYNC_TCP_SSL_ENABLED to your build flags (-DASYNC_TCP_SSL_ENABLED). If you'd like to set a root certificate you can use the setRootCa function on AsyncClient. Feel free to add support for the server side as well :-)
+
+In addition to the regular certificate based cipher suites there is also support for Pre-Shared Key
+cipher suites. Use `setPsk` to define the PSK identifier and PSK itself. The PSK needs to be
+provided in the form of a hex string (and easy way to generate a PSK is to use md5sum).