add http3 variant to protocol enum

actix-http/CHANGES.md

@@ -1,6 +1,9 @@
 # Changes
 
 ## Unreleased - 2021-xx-xx
+### Added
+* Add `Http3` to `Protocol` enum for future compatibility and also mark `#[non_exhaustive]`.
+
 ### Changed
 * Update `actix-*` dependencies to tokio `1.0` based versions. [#1813]
 * Bumped `rand` to `0.8`.

actix-http/src/lib.rs

@@ -72,11 +72,13 @@ pub mod http {
     pub use crate::message::ConnectionType;
 }
 
-/// HTTP protocol
+/// A major HTTP protocol version.
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
+#[non_exhaustive]
 pub enum Protocol {
     Http1,
     Http2,
+    Http3,
 }
 
 type ConnectCallback<IO> = dyn Fn(&IO, &mut Extensions);

actix-http/src/service.rs

@@ -580,6 +580,8 @@ where
                     peer_addr,
                 )),
             },
+
+            proto => unimplemented!("Unsupported HTTP version: {:?}.", proto)
         }
     }
 }