Update handshakestate.rs

Author: dastansam

noise-protocol/src/handshakestate.rs

@@ -432,6 +432,16 @@ where
     pub fn get_pattern(&self) -> &HandshakePattern {
         &self.pattern
     }
+    
+    /// Get the message index of this [`HandshakeState`].
+    pub fn get_index(&self) -> usize {
+        self.message_index
+    }
+
+    /// Set the message index of this [`HandshakeState`] manually.
+    pub fn set_index(&mut self, index: usize) {
+        self.message_index = index;
+    }
 
     /// Check whether it is our turn to send in the handshake state.
     pub fn is_write_turn(&self) -> bool {