review: drop the unused Default derive and correct the FramedRead comment

Nothing builds a default TunnelMessage, and a default one would be an
empty Tunnel Data PDU. The FramedRead comment said the tunnel consumes the
sub-headers before this point; recv drops them, and a caller that needs
them uses recv_message.

Author: glamberson

crates/ironrdp-rdpeudp-tokio/src/framed.rs

@@ -32,9 +32,9 @@ impl FramedRead for UdpTransport {
             // puts no minimum on HigherLayerData, and [MS-RDPBCGR] 1.3.9 sends
             // the four Continuous Auto-Detection messages "encapsulated in the
             // RDP_TUNNEL_SUBHEADER structure ... over the sideband channels
-            // that are in active use". The tunnel has already taken what it
-            // needs from those subheaders by the time we get here, leaving a
-            // payload of nothing to pass on.
+            // that are in active use". `recv` drops those subheaders (a caller
+            // that needs them uses `recv_message`), leaving a payload of
+            // nothing to pass on.
             loop {
                 match self.recv().await {
                     Some(data) if data.is_empty() => continue,

crates/ironrdp-rdpeudp-tokio/src/transport.rs

@@ -220,7 +220,7 @@ impl<T> Drop for AbortOnDrop<T> {
 /// [MS-RDPBCGR] 1.3.9 sends over a sideband channel in use, such as a
 /// bandwidth measurement's Start and Stop and the client's results. `data`
 /// may be empty when a message carries only sub-headers.
-#[derive(Debug, Clone, Default, PartialEq, Eq)]
+#[derive(Debug, Clone, PartialEq, Eq)]
 pub struct TunnelMessage {
     pub sub_headers: Vec<ironrdp_rdpemt::TunnelSubHeader>,
     pub data: Vec<u8>,