Support to generate user-password attribute

src/packet.rs

@@ -35,10 +35,13 @@ impl Packet {
     }
 
     pub fn get_secret(&self) -> &Vec<u8> {
-        // TODO
         &self.secret
     }
 
+    pub fn get_authenticator(&self) -> &Vec<u8> {
+        &self.get_authenticator()
+    }
+
     pub fn parse(bs: &[u8], secret: &[u8]) -> Result<Self, String> {
         if bs.len() < 20 {
             return Err("radius packet doesn't have enough length of bytes; that has to be at least 20 bytes".to_owned());