p2p/enode: don't pass error in AsyncFilter check

Signed-off-by: Csaba Kiraly <[email protected]>

eth/backend.go

@@ -505,9 +505,12 @@ func (s *Ethereum) setupDiscovery() error {
 	// Add DHT nodes from discv4.
 	if s.p2pServer.DiscoveryV4() != nil {
 		iter := s.p2pServer.DiscoveryV4().RandomNodes()
-		resolverFunc := func(ctx context.Context, enr *enode.Node) (*enode.Node, error) {
+		resolverFunc := func(ctx context.Context, enr *enode.Node) *enode.Node {
 			// RequestENR does not yet support context. It will simply time out.
-			return s.p2pServer.DiscoveryV4().RequestENR(enr)
+			// If the ENR can't be resolved, RequestENR will return nil. We don't
+			// care about the specific error here, so we ignore it.
+			nn, _ := s.p2pServer.DiscoveryV4().RequestENR(enr)
+			return nn
 		}
 		iter = enode.AsyncFilter(iter, resolverFunc, maxParallelENRRequests)
 		iter = enode.Filter(iter, eth.NewNodeFilter(s.blockchain))

p2p/enode/iter.go

@@ -163,7 +163,7 @@ type AsyncFilterIter struct {
 	cancel    context.CancelFunc
 	closeOnce sync.Once
 }
-type AsyncFilterFunc func(context.Context, *Node) (*Node, error)
+type AsyncFilterFunc func(context.Context, *Node) *Node
 
 // AsyncFilter creates an iterator which checks nodes in parallel.
 func AsyncFilter(it Iterator, check AsyncFilterFunc, workers int) Iterator {
@@ -192,7 +192,7 @@ func AsyncFilter(it Iterator, check AsyncFilterFunc, workers int) Iterator {
 			<-f.slots
 			// check the node async, in a separate goroutine
 			go func() {
-				if nn, err := check(ctx, n); err == nil {
+				if nn := check(ctx, n); nn != nil {
 					select {
 					case f.passed <- nn:
 					case <-ctx.Done(): // bale out if downstream is already closed and not calling Next