eth, p2p: start the p2p server even if maxpeers == 0

eth/backend.go

@@ -449,14 +449,10 @@ func (s *Ethereum) Start() error {
 		ClientString:    s.net.Name,
 		ProtocolVersion: ProtocolVersion,
 	})
-
-	if s.net.MaxPeers > 0 {
 	err := s.net.Start()
 	if err != nil {
 		return err
 	}
-	}
-
 	// periodically flush databases
 	go s.syncDatabases()
 

p2p/server.go

@@ -275,9 +275,6 @@ func (srv *Server) Start() (err error) {
 	if srv.PrivateKey == nil {
 		return fmt.Errorf("Server.PrivateKey must be set to a non-nil key")
 	}
-	if srv.MaxPeers <= 0 {
-		return fmt.Errorf("Server.MaxPeers must be > 0")
-	}
 	if srv.newTransport == nil {
 		srv.newTransport = newRLPX
 	}