protocols/kad: Check local store on get_providers (#2221)

Author: stuartnelson3

protocols/kad/CHANGELOG.md

@@ -8,7 +8,10 @@
 - Introduce `KademliaStoreInserts` option, which allows to filter records (see
   [PR 2163]).
 
+- Check local store when calling `Kademlia::get_providers` (see [PR 2221]).
+
 [PR 2163]: https://github.com/libp2p/rust-libp2p/pull/2163
+[PR 2221]: https://github.com/libp2p/rust-libp2p/pull/2163
 
 # 0.31.0 [2021-07-12]
 

protocols/kad/src/behaviour.rs

@@ -912,9 +912,16 @@ where
     /// The result of this operation is delivered in a
     /// reported via [`KademliaEvent::OutboundQueryCompleted{QueryResult::GetProviders}`].
     pub fn get_providers(&mut self, key: record::Key) -> QueryId {
+        let providers = self
+            .store
+            .providers(&key)
+            .into_iter()
+            .filter(|p| !p.is_expired(Instant::now()))
+            .map(|p| p.provider)
+            .collect();
         let info = QueryInfo::GetProviders {
             key: key.clone(),
-            providers: HashSet::new(),
+            providers,
         };
         let target = kbucket::Key::new(key);
         let peers = self.kbuckets.closest_keys(&target);

protocols/kad/src/behaviour/test.rs

@@ -1317,3 +1317,51 @@ fn network_behaviour_inject_address_change() {
         kademlia.addresses_of_peer(&remote_peer_id),
     );
 }
+
+#[test]
+fn get_providers() {
+    fn prop(key: record::Key) {
+        let (_, mut single_swarm) = build_node();
+        single_swarm
+            .behaviour_mut()
+            .start_providing(key.clone())
+            .expect("could not provide");
+
+        block_on(async {
+            match single_swarm.next().await.unwrap() {
+                SwarmEvent::Behaviour(KademliaEvent::OutboundQueryCompleted {
+                    result: QueryResult::StartProviding(Ok(_)),
+                    ..
+                }) => {}
+                SwarmEvent::Behaviour(e) => panic!("Unexpected event: {:?}", e),
+                _ => {}
+            }
+        });
+
+        let query_id = single_swarm.behaviour_mut().get_providers(key.clone());
+
+        block_on(async {
+            match single_swarm.next().await.unwrap() {
+                SwarmEvent::Behaviour(KademliaEvent::OutboundQueryCompleted {
+                    id,
+                    result:
+                        QueryResult::GetProviders(Ok(GetProvidersOk {
+                            key: found_key,
+                            providers,
+                            ..
+                        })),
+                    ..
+                }) if id == query_id => {
+                    assert_eq!(key, found_key);
+                    assert_eq!(
+                        single_swarm.local_peer_id(),
+                        providers.iter().next().unwrap()
+                    );
+                }
+                SwarmEvent::Behaviour(e) => panic!("Unexpected event: {:?}", e),
+                _ => {}
+            }
+        });
+    }
+    QuickCheck::new().tests(10).quickcheck(prop as fn(_))
+}