feat: replace ProtocolName with AsRef<str>

Previously, a protocol could be any sequence of bytes as long as it started with `/`. Now, we directly parse a protocol as `String` which enforces it to be valid UTF8.

To notify users of this change, we delete the `ProtocolName` trait. The new requirement is that users need to provide a type that implements `AsRef<str>`.

We also add a `StreamProtocol` newtype in `libp2p-swarm` which provides an easy way for users to ensure their protocol strings are compliant. The newtype enforces that protocol strings start with `/`. `StreamProtocol` also implements `AsRef<str>`, meaning users can directly use it in their upgrades.

`multistream-select` by itself only changes marginally with this patch. The only thing we enforce in the type-system is that protocols must implement `AsRef<str>`.

Resolves: #2831.

Pull-Request: #3746.

protocols/perf/src/client/handler.rs

@@ -31,7 +31,7 @@ use libp2p_swarm::{
         ConnectionEvent, DialUpgradeError, FullyNegotiatedInbound, FullyNegotiatedOutbound,
         ListenUpgradeError,
     },
-    ConnectionHandler, ConnectionHandlerEvent, ConnectionHandlerUpgrErr, KeepAlive,
+    ConnectionHandler, ConnectionHandlerEvent, ConnectionHandlerUpgrErr, KeepAlive, StreamProtocol,
     SubstreamProtocol,
 };
 use void::Void;
@@ -90,7 +90,7 @@ impl ConnectionHandler for Handler {
     type OutEvent = Event;
     type Error = Void;
     type InboundProtocol = DeniedUpgrade;
-    type OutboundProtocol = ReadyUpgrade<&'static [u8]>;
+    type OutboundProtocol = ReadyUpgrade<StreamProtocol>;
     type OutboundOpenInfo = ();
     type InboundOpenInfo = ();
 

protocols/perf/src/lib.rs

@@ -24,8 +24,10 @@
 
 #![cfg_attr(docsrs, feature(doc_cfg, doc_auto_cfg))]
 
+use libp2p_swarm::StreamProtocol;
+
 pub mod client;
 mod protocol;
 pub mod server;
 
-pub const PROTOCOL_NAME: &[u8; 11] = b"/perf/1.0.0";
+pub const PROTOCOL_NAME: StreamProtocol = StreamProtocol::new("/perf/1.0.0");

protocols/perf/src/server/handler.rs

@@ -30,7 +30,7 @@ use libp2p_swarm::{
         ConnectionEvent, DialUpgradeError, FullyNegotiatedInbound, FullyNegotiatedOutbound,
         ListenUpgradeError,
     },
-    ConnectionHandler, ConnectionHandlerEvent, ConnectionHandlerUpgrErr, KeepAlive,
+    ConnectionHandler, ConnectionHandlerEvent, ConnectionHandlerUpgrErr, KeepAlive, StreamProtocol,
     SubstreamProtocol,
 };
 use log::error;
@@ -67,7 +67,7 @@ impl ConnectionHandler for Handler {
     type InEvent = Void;
     type OutEvent = Event;
     type Error = Void;
-    type InboundProtocol = ReadyUpgrade<&'static [u8]>;
+    type InboundProtocol = ReadyUpgrade<StreamProtocol>;
     type OutboundProtocol = DeniedUpgrade;
     type OutboundOpenInfo = Void;
     type InboundOpenInfo = ();