qlog: add basic DATAGRAM frame logging

Previously, we logged DATAGRAM frames as a generic "unknown" frame
event with a hard-coded frame type of 0x30. This change adds a
proper frame definition that results in such frames getting logged
as "datagram" along with the length of the frame payload.

src/frame.rs

@@ -905,7 +905,8 @@ impl Frame {
 
             Frame::HandshakeDone => qlog::QuicFrame::handshake_done(),
 
-            Frame::Datagram { .. } => qlog::QuicFrame::unknown(0x30),
+            Frame::Datagram { data } =>
+                qlog::QuicFrame::datagram(data.len().to_string(), None),
         }
     }
 }

tools/qlog/src/lib.rs

@@ -1652,6 +1652,7 @@ pub enum QuicFrameTypeName {
     ConnectionClose,
     ApplicationClose,
     HandshakeDone,
+    Datagram,
     Unknown,
 }
 
@@ -1966,6 +1967,13 @@ pub enum QuicFrame {
         frame_type: QuicFrameTypeName,
     },
 
+    Datagram {
+        frame_type: QuicFrameTypeName,
+        length: String,
+
+        raw: Option<String>,
+    },
+
     Unknown {
         frame_type: QuicFrameTypeName,
         raw_frame_type: u64,
@@ -2149,6 +2157,14 @@ impl QuicFrame {
         }
     }
 
+    pub fn datagram(length: String, raw: Option<String>) -> Self {
+        QuicFrame::Datagram {
+            frame_type: QuicFrameTypeName::Datagram,
+            length,
+            raw,
+        }
+    }
+
     pub fn unknown(raw_frame_type: u64) -> Self {
         QuicFrame::Unknown {
             frame_type: QuicFrameTypeName::Unknown,