added banned address error

p2p/pex/errors.go

@@ -63,3 +63,11 @@ type ErrAddrBookInvalidAddr struct {
 func (err ErrAddrBookInvalidAddr) Error() string {
 	return fmt.Sprintf("Cannot add invalid address %v: %v", err.Addr, err.AddrErr)
 }
+
+type ErrAddressBanned struct {
+	Addr *p2p.NetAddress
+}
+
+func (err ErrAddressBanned) Error() string {
+	return fmt.Sprintf("Address: %v is currently banned", err.Addr)
+}