Add rate limiter check to handshake messages.

src/handshake/types.rs

@@ -43,6 +43,7 @@ pub enum HandshakeError {
     OldTimestamp,
     InvalidState,
     InvalidMac1,
+    RateLimited
 }
 
 impl fmt::Display for HandshakeError {
@@ -57,6 +58,7 @@ impl fmt::Display for HandshakeError {
             HandshakeError::OldTimestamp => write!(f, "Timestamp is less/equal to the newest"),
             HandshakeError::InvalidState => write!(f, "Message does not apply to handshake state"),
             HandshakeError::InvalidMac1 => write!(f, "Message has invalid mac1 field"),
+            HandshakeError::RateLimited => write!(f, "Message was dropped by rate limiter")
         }
     }
 }