introduce locations

This prepares the identity layer for transports where an identity alone
doesn't say where a node is.  The identity layer keeps identities in its
books and publishes locations.  For Mycelium and the simulator both
methods default to the identity, so nothing changes there.

1 files changed, 16 insertions, 0 deletions

diff --git a/src/transport/mod.rs b/src/transport/mod.rs
index cbbef45..58e71d8 100644
--- a/src/transport/mod.rs
+++ b/src/transport/mod.rs
@@ -531,6 +531,22 @@ pub(crate) trait Transport: Send + Sync {
         vec![self.local_id().to_owned()]
     }
 
+    /// For a transport under the identity layer: the transport identity at `target`, an
+    /// address of this transport without its scheme, noting where it is if `target` says
+    /// more than who (as a libp2p multiaddr ending in the peer ID does). None if
+    /// `target` isn't one of this transport's. By default `target` itself, for a
+    /// transport whose identities are addresses.
+    fn locate(&self, target: &str) -> Option<String> {
+        self.is_peer_id(target).then(|| target.to_owned())
+    }
+
+    /// For a transport under the identity layer: where the node with transport identity
+    /// `target` is, as addresses others can use (`locate` reads them). By default
+    /// `target` itself, as for `locate`.
+    fn locations(&self, target: &str) -> Vec<String> {
+        vec![target.to_owned()]
+    }
+
     /// Where `peer` can be reached, as far as this node knows: passed on to others (in
     /// a HELLO_REPLY). By default its identity, as for `local_addresses`.
     fn addresses_of(&self, peer: &str) -> Vec<String> {