ProtocolId can now be more than 3 bytes (#2350)

substrate/core/network-libp2p/src/lib.rs

@@ -38,8 +38,22 @@ use serde_derive::{Deserialize, Serialize};
 use slog_derive::SerdeValue;
 use std::{collections::{HashMap, HashSet}, error, fmt, time::Duration};
 
-/// Protocol / handler id
-pub type ProtocolId = [u8; 3];
+/// Name of a protocol, transmitted on the wire. Should be unique for each chain.
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct ProtocolId(smallvec::SmallVec<[u8; 6]>);
+
+impl<'a> From<&'a [u8]> for ProtocolId {
+	fn from(bytes: &'a [u8]) -> ProtocolId {
+		ProtocolId(bytes.into())
+	}
+}
+
+impl ProtocolId {
+	/// Exposes the `ProtocolId` as bytes.
+	pub fn as_bytes(&self) -> &[u8] {
+		self.0.as_ref()
+	}
+}
 
 /// Parses a string address and returns the component, if valid.
 pub fn parse_str_addr(addr_str: &str) -> Result<(PeerId, Multiaddr), ParseErr> {