Feature/bacnet discover dnet devices (#583)

* Added an example application to discover devices and their objects and properties on a specific destination network. The application uses a BACnet Discovery FSM module along with the BACnet R/W FSM.  The BACnet Discovery module stores the binary property data in Keylists and includes device object property queries and iterators.

* Added callback from BACnet R/W FSM module for I-Am messages.

* Removed dependency in BACnet R/W FSM module on rpm_ack_decode_service_request() which uses calloc/free value lists.  Created an alternate RPM-ACK to RP-ACK processing function.

* Changed RPM handler to skip over unknown property values

src/bacnet/basic/client/bac-discover.h

@@ -0,0 +1,136 @@
+/**
+ * @file
+ * @author Steve Karg <skarg@users.sourceforge.net>
+ * @date 2024
+ *
+ * SPDX-License-Identifier: MIT
+ */
+#ifndef BAC_DISCOVER_H
+#define BAC_DISCOVER_H
+
+#include <stdbool.h>
+#include <stdint.h>
+#include "bacnet/bacdef.h"
+#include "bacnet/bacenum.h"
+#include "bacnet/bacapp.h"
+#include "bacnet/rp.h"
+#include "bacnet/bacnet_stack_exports.h"
+
+/**
+ * @brief Callback function for iterating the results of the device discovery.
+ * @param device_id [in] The device ID of the data
+ * @param device_index [in] The index of the device in the list of discovered devices
+ * @param object_index [in] The index of the object in the list of discovered objects in the device
+ * @param property_index [in] The index of the property in the list of discovered properties in the object in the device
+ * @param rp_data [in] The contents of the device object property
+ * @param context_data [in] The context data passed to the discover function
+ * @return true if the iteration should continue, false if it should stop
+*/
+typedef bool (*bacnet_discover_device_callback) (
+    uint32_t device_id,
+    unsigned device_index,
+    unsigned object_index,
+    unsigned property_index,
+    BACNET_READ_PROPERTY_DATA * rp_data,
+    void *context_data);
+
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
+BACNET_STACK_EXPORT
+void bacnet_discover_cleanup(void);
+
+BACNET_STACK_EXPORT
+int bacnet_discover_device_count(void);
+BACNET_STACK_EXPORT
+uint32_t bacnet_discover_device_instance(unsigned index);
+BACNET_STACK_EXPORT
+int bacnet_discover_device_object_count(uint32_t device_id);
+BACNET_STACK_EXPORT
+bool bacnet_discover_device_object_identifier(uint32_t device_id, 
+    unsigned index, BACNET_OBJECT_ID *object_id);
+BACNET_STACK_EXPORT
+unsigned long bacnet_discover_device_elapsed_milliseconds(
+    uint32_t device_id);
+BACNET_STACK_EXPORT
+size_t bacnet_discover_device_memory(
+    uint32_t device_id);
+BACNET_STACK_EXPORT
+unsigned int bacnet_discover_object_property_count(
+    uint32_t device_id,
+    BACNET_OBJECT_TYPE object_type,
+    uint32_t object_instance);
+BACNET_STACK_EXPORT
+bool bacnet_discover_object_property_identifier(
+    uint32_t device_id, 
+    BACNET_OBJECT_TYPE object_type,
+    uint32_t object_instance,
+    unsigned index, 
+    uint32_t *property_id);
+BACNET_STACK_EXPORT
+bool bacnet_discover_property_value(uint32_t device_id,
+    BACNET_OBJECT_TYPE object_type,
+    uint32_t object_instance,
+    BACNET_PROPERTY_ID object_property,
+    BACNET_APPLICATION_DATA_VALUE *value);
+BACNET_STACK_EXPORT
+bool bacnet_discover_property_name(uint32_t device_id,
+    BACNET_OBJECT_TYPE object_type,
+    uint32_t object_instance,
+    BACNET_PROPERTY_ID object_property,
+    char *buffer,
+    size_t buffer_len,
+    const char *default_string);
+
+BACNET_STACK_EXPORT
+bool bacnet_discover_device_object_property_iterate(
+    uint32_t device_id,
+    BACNET_OBJECT_TYPE object_type,
+    uint32_t object_instance,
+    bacnet_discover_device_callback callback, void *context);
+BACNET_STACK_EXPORT
+bool bacnet_discover_device_object_iterate(
+    uint32_t device_id,
+    bacnet_discover_device_callback callback, void *context);
+BACNET_STACK_EXPORT
+bool bacnet_discover_device_iterate(
+    bacnet_discover_device_callback callback, void *context);
+
+BACNET_STACK_EXPORT
+void bacnet_discover_task(void);
+
+BACNET_STACK_EXPORT
+void bacnet_discover_dnet_set(uint16_t dnet);
+BACNET_STACK_EXPORT
+uint16_t bacnet_discover_dnet(void);
+
+BACNET_STACK_EXPORT
+void bacnet_discover_vendor_id_set(uint16_t vendor_id);
+BACNET_STACK_EXPORT
+uint16_t bacnet_discover_vendor_id(void);
+
+BACNET_STACK_EXPORT
+void bacnet_discover_seconds_set(unsigned int seconds);
+BACNET_STACK_EXPORT
+unsigned int bacnet_discover_seconds(void);
+
+BACNET_STACK_EXPORT
+void bacnet_discover_read_process_milliseconds_set(unsigned long milliseconds);
+BACNET_STACK_EXPORT
+unsigned long bacnet_discover_read_process_milliseconds(void);
+
+BACNET_STACK_EXPORT
+void bacnet_discover_device_add(
+    uint32_t device_instance,
+    unsigned max_apdu,
+    int segmentation,
+    uint16_t vendor_id);
+
+BACNET_STACK_EXPORT
+void bacnet_discover_init(void);
+
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+#endif