add prometheus-middlewares for http and ws endpoint

pkg/rpc/check.go

@@ -0,0 +1,21 @@
+package rpc
+
+import "github.com/ethereum/go-ethereum/rpc"
+
+// checkModuleAvailability check that all names given in modules are actually
+// available API services.
+func checkModuleAvailability(modules []string, apis []rpc.API) (bad, available []string) {
+	availableSet := make(map[string]struct{})
+	for _, api := range apis {
+		if _, ok := availableSet[api.Namespace]; !ok {
+			availableSet[api.Namespace] = struct{}{}
+			available = append(available, api.Namespace)
+		}
+	}
+	for _, name := range modules {
+		if _, ok := availableSet[name]; !ok {
+			bad = append(bad, name)
+		}
+	}
+	return bad, available
+}