listpeers: correctly display features on reconnect.

peer features are only kept for connected peers (as they can change),
but we didn't update them on reconnect.  The main effect was that
after a restart we displayed the features as empty, even after
reconnect.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

lightningd/peer_control.c

@@ -78,6 +78,18 @@ static void copy_to_parent_log(const char *prefix,
 		log_(parent_log, level, "%s %s", prefix, str);
 }
 
+static void peer_update_features(struct peer *peer,
+				 const u8 *gfeatures TAKES,
+				 const u8 *lfeatures TAKES)
+{
+	tal_free(peer->global_features);
+	tal_free(peer->local_features);
+	peer->global_features = tal_dup_arr(peer, u8,
+					    gfeatures, tal_count(gfeatures), 0);
+	peer->local_features = tal_dup_arr(peer, u8,
+					   lfeatures, tal_count(lfeatures), 0);
+}
+
 struct peer *new_peer(struct lightningd *ld, u64 dbid,
 		      const struct pubkey *id,
 		      const struct wireaddr_internal *addr,
@@ -97,10 +109,8 @@ struct peer *new_peer(struct lightningd *ld, u64 dbid,
 		peer->addr.itype = ADDR_INTERNAL_WIREADDR;
 		peer->addr.u.wireaddr.type = ADDR_TYPE_PADDING;
 	}
-	peer->global_features = tal_dup_arr(peer, u8,
+	peer->global_features = peer->local_features = NULL;
-					    gfeatures, tal_count(gfeatures), 0);
+	peer_update_features(peer, gfeatures, lfeatures);
-	peer->local_features = tal_dup_arr(peer, u8,
-					   lfeatures, tal_count(lfeatures), 0);
 	list_head_init(&peer->channels);
 	peer->direction = get_channel_direction(&peer->ld->id, &peer->id);
 
@@ -447,6 +457,8 @@ void peer_connected(struct lightningd *ld, const u8 *msg,
 	peer = peer_by_id(ld, &id);
 	if (!peer)
 		peer = new_peer(ld, 0, &id, &addr, gfeatures, lfeatures);
+	else
+		peer_update_features(peer, gfeatures, lfeatures);
 
 	/* Can't be opening, since we wouldn't have sent peer_disconnected. */
 	assert(!peer->uncommitted_channel);

tests/test_connection.py

@@ -1002,7 +1002,7 @@ def test_forget_channel(node_factory):
 
 
 def test_peerinfo(node_factory, bitcoind):
-    l1, l2 = node_factory.line_graph(2, fundchannel=False)
+    l1, l2 = node_factory.line_graph(2, fundchannel=False, opts={'may_reconnect': True})
     # Gossiping but no node announcement yet
     assert l1.rpc.getpeer(l2.info['id'])['connected']
     assert len(l1.rpc.getpeer(l2.info['id'])['channels']) == 0
@@ -1024,6 +1024,16 @@ def test_peerinfo(node_factory, bitcoind):
     assert only_one(nodes1)['global_features'] == peer1['global_features']
     assert only_one(nodes2)['global_features'] == peer2['global_features']
 
+    assert l1.rpc.getpeer(l2.info['id'])['local_features'] == '8a'
+    assert l2.rpc.getpeer(l1.info['id'])['local_features'] == '8a'
+
+    # If it reconnects after db load, it should know features.
+    l1.restart()
+    wait_for(lambda: l1.rpc.getpeer(l2.info['id'])['connected'])
+    wait_for(lambda: l2.rpc.getpeer(l1.info['id'])['connected'])
+    assert l1.rpc.getpeer(l2.info['id'])['local_features'] == '8a'
+    assert l2.rpc.getpeer(l1.info['id'])['local_features'] == '8a'
+
     # Close the channel to forget the peer
     with pytest.raises(RpcError, match=r'Channel close negotiation not finished'):
         l1.rpc.close(chan, False, 0)