kad: Export QueryId and add Kademlia::protocol_name. (#1469)

The `QueryId` type should be exported as it is used in the
`NetworkBehaviour::ProtocolsHandler` type of `Kademlia`.

`Kademlia::protocol_name` is added for convenience.

protocols/kad/src/behaviour.rs

@@ -222,6 +222,13 @@ where
         Self::with_config(id, store, Default::default())
     }
 
+    /// Get the protocol name of this kademlia instance.
+    pub fn protocol_name(&self) -> &[u8] {
+        self.protocol_name_override
+            .as_ref()
+            .map_or(crate::protocol::DEFAULT_PROTO_NAME.as_ref(), AsRef::as_ref)
+    }
+
     /// Creates a new `Kademlia` network behaviour with the given configuration.
     pub fn with_config(id: PeerId, store: TStore, config: KademliaConfig) -> Self {
         let local_key = kbucket::Key::new(id.clone());

protocols/kad/src/lib.rs

@@ -65,6 +65,7 @@ pub use behaviour::{
     GetProvidersOk,
     GetProvidersError,
 };
+pub use query::QueryId;
 pub use protocol::KadConnectionType;
 pub use record::{store, Record, ProviderRecord};
 

protocols/kad/src/protocol.rs

@@ -40,6 +40,9 @@ use std::{io, iter};
 use unsigned_varint::codec;
 use wasm_timer::Instant;
 
+/// The protocol name used for negotiating with multistream-select.
+pub const DEFAULT_PROTO_NAME: &[u8] = b"/ipfs/kad/1.0.0";
+
 /// Status of our connection to a node reported by the Kademlia protocol.
 #[derive(Copy, Clone, PartialEq, Eq, Debug, Hash)]
 pub enum KadConnectionType {
@@ -152,7 +155,7 @@ impl KademliaProtocolConfig {
 impl Default for KademliaProtocolConfig {
     fn default() -> Self {
         KademliaProtocolConfig {
-            protocol_name: Cow::Borrowed(b"/ipfs/kad/1.0.0"),
+            protocol_name: Cow::Borrowed(DEFAULT_PROTO_NAME)
         }
     }
 }