More ergonomic api when STD is available

matter/src/core.rs

@@ -54,6 +54,14 @@ pub struct Matter<'a> {
 }
 
 impl<'a> Matter<'a> {
+    #[cfg(feature = "std")]
+    pub fn new_default(dev_det: &'a BasicInfoConfig, mdns: &'a mut dyn Mdns) -> Self {
+        use crate::utils::epoch::{sys_epoch, sys_utc_calendar};
+        use crate::utils::rand::sys_rand;
+
+        Self::new(dev_det, mdns, sys_epoch, sys_rand, sys_utc_calendar)
+    }
+
     /// Creates a new Matter object
     ///
     /// # Parameters

matter/src/transport/mgr.rs

@@ -191,18 +191,18 @@ impl<'a> TransportMgr<'a> {
     pub fn new<
         T: Borrow<RefCell<FabricMgr>>
             + Borrow<RefCell<PaseMgr>>
+            + Borrow<RefCell<MdnsMgr<'a>>>
             + Borrow<Epoch>
             + Borrow<Rand>
             + Borrow<UtcCalendar>,
     >(
         matter: &'a T,
-        mdns_mgr: &'a RefCell<MdnsMgr<'a>>,
     ) -> Self {
         Self::wrap(
             SecureChannel::new(
                 matter.borrow(),
                 matter.borrow(),
-                mdns_mgr,
+                matter.borrow(),
                 *matter.borrow(),
                 *matter.borrow(),
             ),

matter/src/utils/rand.rs

@@ -1,3 +1,10 @@
 pub type Rand = fn(&mut [u8]);
 
 pub fn dummy_rand(_buf: &mut [u8]) {}
+
+#[cfg(feature = "std")]
+pub fn sys_rand(buf: &mut [u8]) {
+    use rand::{thread_rng, RngCore};
+
+    thread_rng().fill_bytes(buf);
+}