Add WebSocket :protocol extension per RFC 9220. (#236)

Author: vi

h3/src/ext.rs

@@ -15,6 +15,8 @@ impl Protocol {
     pub const CONNECT_UDP: Protocol = Protocol(ProtocolInner::ConnectUdp);
     /// RFC 9484 protocol
     pub const CONNECT_IP: Protocol = Protocol(ProtocolInner::ConnectIp);
+    /// RFC 9220 (WebSocket) protocol
+    pub const WEBSOCKET: Protocol = Protocol(ProtocolInner::WebSocket);
 
     /// Return a &str representation of the `:protocol` pseudo-header value
     #[inline]
@@ -23,6 +25,7 @@ impl Protocol {
             ProtocolInner::WebTransport => "webtransport",
             ProtocolInner::ConnectUdp => "connect-udp",
             ProtocolInner::ConnectIp => "connect-ip",
+            ProtocolInner::WebSocket => "websocket",
         }
     }
 }
@@ -32,6 +35,7 @@ enum ProtocolInner {
     WebTransport,
     ConnectUdp,
     ConnectIp,
+    WebSocket,
 }
 
 /// Error when parsing the protocol
@@ -45,6 +49,7 @@ impl FromStr for Protocol {
             "webtransport" => Ok(Self(ProtocolInner::WebTransport)),
             "connect-udp" => Ok(Self(ProtocolInner::ConnectUdp)),
             "connect-ip" => Ok(Self(ProtocolInner::ConnectIp)),
+            "websocket" => Ok(Self(ProtocolInner::WebSocket)),
             _ => Err(InvalidProtocol),
         }
     }