p2p: fix missing error from SendReceive (#1304)

Fixes issue with `PeerInfo` protocol reporting `zero` values like `SentAt`. This was due to missing returned error from `p2p.Sender.SendReceive`.

category: bug
ticket: #1295

app/peerinfo/peerinfo.go

@@ -79,7 +79,7 @@ func newInternal(tcpNode host.Host, peers []peer.ID, version string, lockHash []
 	// Register a simple handler that returns our info and ignores the request.
 	registerHandler("peerinfo", tcpNode, protocolID,
 		func() proto.Message { return new(pbv1.PeerInfo) },
-		func(ctx context.Context, peerID peer.ID, req proto.Message) (proto.Message, bool, error) {
+		func(context.Context, peer.ID, proto.Message) (proto.Message, bool, error) {
 			return &pbv1.PeerInfo{
 				CharonVersion: version,
 				LockHash:      lockHash,

p2p/sender.go

@@ -105,7 +105,8 @@ func (s *Sender) addResult(ctx context.Context, peerID peer.ID, err error) {
 	s.states.Store(peerID, state) // Note there is a race if two results for the same peer is added at the same time, but this isn't critical.
 }
 
-// SendAsync returns nil sends a libp2p message asynchronously. It logs results on state change (success to/from failure).
+// SendAsync returns nil and sends a libp2p message asynchronously.
+// It logs results on state change (success to/from failure).
 // It implements SendFunc.
 func (s *Sender) SendAsync(parent context.Context, tcpNode host.Host, protoID protocol.ID, peerID peer.ID, msg proto.Message) error {
 	go func() {
@@ -119,17 +120,20 @@ func (s *Sender) SendAsync(parent context.Context, tcpNode host.Host, protoID pr
 }
 
 // SendReceive sends and receives a libp2p request and response message pair synchronously and then closes the stream.
-// It returns false on any error and applies log filtering.
+// The provided response proto will be populated if err is nil.
+// It logs results on state change (success to/from failure).
 // It implements SendReceiveFunc.
 func (s *Sender) SendReceive(ctx context.Context, tcpNode host.Host, peerID peer.ID, req, resp proto.Message, protocols ...protocol.ID) error {
 	err := SendReceive(ctx, tcpNode, peerID, req, resp, protocols...)
 	s.addResult(ctx, peerID, err)
 
-	return nil
+	return err
 }
 
 // SendReceive sends and receives a libp2p request and response message
-// pair synchronously and then closes the stream. It implements SendReceiveFunc.
+// pair synchronously and then closes the stream.
+// The provided response proto will be populated if err is nil.
+// It implements SendReceiveFunc.
 func SendReceive(ctx context.Context, tcpNode host.Host, peerID peer.ID,
 	req, resp proto.Message, protocols ...protocol.ID,
 ) error {