Added option to use task PID for EUI seed under native POSIX (#49)

* Changed EUI seed to use task PID for native POSIX
* Use Kconfig to switch between RNG and PID based EUI generation
* Add BOARD_NATIVE_POSIX dependency to Kconfig

Co-authored-by: Simon Gilbert <Simon.Gilbert@Brillpower.com>

Kconfig

@@ -62,6 +62,11 @@ config THINGSET_GENERATE_NODE_ID
 	select CRC
 	default y
 
+config THINGSET_PID_EUI
+	bool "Use task PID as EUI basis for EUI generation"
+	depends on THINGSET_GENERATE_NODE_ID
+	depends on BOARD_NATIVE_POSIX
+
 config THINGSET_NODE_NAME
 	string "Default ThingSet node name"
 	default "ThingSet Node"

src/sdk.c

@@ -17,6 +17,10 @@
 #include <thingset.h>
 #include <thingset/sdk.h>
 
+#ifdef CONFIG_THINGSET_PID_EUI
+#include <unistd.h>
+#endif
+
 LOG_MODULE_REGISTER(thingset_sdk, CONFIG_THINGSET_SDK_LOG_LEVEL);
 
 /*
@@ -119,10 +123,19 @@ static void generate_device_eui()
 #ifndef CONFIG_BOARD_NATIVE_POSIX
     hwinfo_get_device_id(buf, sizeof(buf));
 #else
+
+#ifndef CONFIG_THINGSET_PID_EUI
     /* hwinfo is not available in native_posix, so we use random data instead */
     for (int i = 0; i < sizeof(buf); i++) {
         buf[i] = sys_rand32_get() & 0xFF;
     }
+#else
+    /* hwinfo is not available in native_posix, so we take task PID instead */
+    int pid = getpid();
+
+    snprintk(buf, sizeof(buf), "%X", pid);
+#endif
+
 #endif
 
     crc = crc32_ieee(buf, 8);