Porting HTTP Mutual Auth Demo from C-SDK (FreeRTOS#414)

Add demo to establish a mutually-authenticated network connection with the server before sending and verifying a simple POST request.
* Add demo files
* Move all "Http_Demo_Helpers" files into Common
* Update project files and add vendor config files
* Update http_demo_utils.c after backoff updates

FreeRTOS-Plus/Demo/coreHTTP_Windows_Simulator/Http_Demo_Helpers/http_demo_utils.c → FreeRTOS-Plus/Demo/coreHTTP_Windows_Simulator/Common/http_demo_utils.c

@@ -1,5 +1,5 @@
 /*
- * FreeRTOS Kernel V10.3.0
+ * FreeRTOS V202011.00
  * Copyright (C) 2020 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy of
@@ -18,6 +18,10 @@
  * 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.
+ *
+ * https://www.FreeRTOS.org
+ * https://github.com/FreeRTOS
+ *
  */
 
 /* Standard includes. */
@@ -33,6 +37,49 @@
 
 /*-----------------------------------------------------------*/
 
+/**
+ * @brief The maximum number of retries for network operation with server.
+ */
+#define MAX_RETRY_ATTEMPTS            ( 5U )
+
+/**
+ * @brief The maximum back-off delay (in milliseconds) for retrying failed
+ * operation with server.
+ */
+#define RETRY_MAX_BACKOFF_DELAY_MS    ( 5000U )
+
+/**
+ * @brief The base back-off delay (in milliseconds) to use for network operation
+ * retry attempts.
+ */
+#define RETRY_BACKOFF_BASE_MS         ( 500U )
+
+/*-----------------------------------------------------------*/
+
+/**
+ * @brief A wrapper to the "uxRand()" random number generator so that it
+ * can be passed to the backoffAlgorithm library for retry logic.
+ *
+ * This function implements the #BackoffAlgorithm_RNG_T type interface
+ * in the backoffAlgorithm library API.
+ *
+ * @note The "uxRand" function represents a pseudo random number generator.
+ * However, it is recommended to use a True Randon Number Generator (TRNG)
+ * for generating unique device-specific random values to avoid possibility
+ * of network collisions from multiple devices retrying network operations.
+ *
+ * @return The generated randon number. This function ALWAYS succeeds.
+ */
+static int32_t prvGenerateRandomNumber();
+
+/*-----------------------------------------------------------*/
+
+static int32_t prvGenerateRandomNumber()
+{
+    return( uxRand() & INT32_MAX );
+}
+
+/*-----------------------------------------------------------*/
 BaseType_t connectToServerWithBackoffRetries( TransportConnect_t connectFunction,
                                               NetworkContext_t * pxNetworkContext )
 {
@@ -41,14 +88,15 @@ BaseType_t connectToServerWithBackoffRetries( TransportConnect_t connectFunction
     BackoffAlgorithmStatus_t xBackoffAlgStatus = BackoffAlgorithmSuccess;
     /* Struct containing the next backoff time. */
     BackoffAlgorithmContext_t xReconnectParams;
+    uint16_t usNextBackoff = 0U;
 
     assert( connectFunction != NULL );
 
     /* Initialize reconnect attempts and interval */
     BackoffAlgorithm_InitializeParams( &xReconnectParams,
                                        RETRY_BACKOFF_BASE_MS,
                                        RETRY_MAX_BACKOFF_DELAY_MS,
-                                       RETRY_MAX_ATTEMPTS,
+                                       MAX_RETRY_ATTEMPTS,
                                        prvGenerateRandomNumber );
 
     /* Attempt to connect to the HTTP server. If connection fails, retry after a

FreeRTOS-Plus/Demo/coreHTTP_Windows_Simulator/Http_Demo_Helpers/http_demo_utils.h → FreeRTOS-Plus/Demo/coreHTTP_Windows_Simulator/Common/http_demo_utils.h

@@ -1,5 +1,5 @@
 /*
- * FreeRTOS Kernel V10.3.0
+ * FreeRTOS V202011.00
  * Copyright (C) 2020 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy of
@@ -18,6 +18,10 @@
  * 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.
+ *
+ * https://www.FreeRTOS.org
+ * https://github.com/FreeRTOS
+ *
  */
 
 #ifndef HTTP_DEMO_UTILS_H
@@ -32,9 +36,6 @@
 #include "FreeRTOS.h"
 #include "task.h"
 
-/* Transport interface implementation include header for TLS. */
-#include "using_mbedtls.h"
-
 /* HTTP API header. */
 #include "core_http_client.h"