p2p: added received at to peer message

p2p.Msg.ReceivedAt can be used for determining block propagation from
begining to end.

p2p/message.go

@@ -25,6 +25,7 @@ type Msg struct {
 	Code       uint64
 	Size       uint32 // size of the paylod
 	Payload    io.Reader
+	ReceivedAt time.Time
 }
 
 // Decode parses the RLP content of a message into

p2p/peer.go

@@ -177,6 +177,7 @@ func (p *Peer) readLoop(errc chan<- error) {
 			errc <- err
 			return
 		}
+		msg.ReceivedAt = time.Now()
 		if err = p.handle(msg); err != nil {
 			errc <- err
 			return