AP_HAL_Linux: add support for hw random number generation

libraries/AP_HAL_Linux/Util.cpp

@@ -287,3 +287,21 @@ void *Util::heap_realloc(void *h, void *ptr, size_t new_size)
 }
 
 #endif // ENABLE_HEAP
+
+/**
+ * This method will read random values with set size.
+ */
+bool Util::get_random_vals(uint8_t* data, size_t size)
+{
+    int dev_random = open("/dev/urandom", O_RDONLY);
+    if (dev_random < 0) {
+        return false;
+    }
+    ssize_t result = read(dev_random, data, size);
+    if (result < 0) {
+        close(dev_random);
+        return false;
+    }
+    close(dev_random);
+    return true;
+}

libraries/AP_HAL_Linux/Util.h

@@ -94,6 +94,9 @@ public:
         _toneAlarm.set_buzzer_tone(frequency, volume, duration_ms);
     }
 
+    // fills data with random values of requested size
+    bool get_random_vals(uint8_t* data, size_t size) override;
+
 private:
 #if CONFIG_HAL_BOARD_SUBTYPE == HAL_BOARD_SUBTYPE_LINUX_DISCO
     static ToneAlarm_Disco _toneAlarm;