grpcutil: extract IsGRPCRequest

util/grpcutil/grpc_util.go

@@ -61,16 +61,22 @@ func ListenAndServeGRPC(stopper *stop.Stopper, server *grpc.Server, addr net.Add
 // connections or otherHandler otherwise.
 func GRPCHandlerFunc(grpcServer *grpc.Server, otherHandler http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		// TODO(tamird): point to merged gRPC code rather than a PR.
-		// This is a partial recreation of gRPC's internal checks https://github.com/grpc/grpc-go/pull/514/files#diff-95e9a25b738459a2d3030e1e6fa2a718R61
-		if r.ProtoMajor == 2 && strings.Contains(r.Header.Get("Content-Type"), "application/grpc") {
+		if IsGRPCRequest(r) {
 			grpcServer.ServeHTTP(w, r)
 		} else {
 			otherHandler.ServeHTTP(w, r)
 		}
 	})
 }
 
+// IsGRPCRequest returns true if r came from a grpc client.
+//
+// Its logic is a partial recreation of gRPC's internal checks, see
+// https://github.com/grpc/grpc-go/blob/01de3de/transport/handler_server.go#L61:L69
+func IsGRPCRequest(r *http.Request) bool {
+	return r.ProtoMajor == 2 && strings.Contains(r.Header.Get("Content-Type"), "application/grpc")
+}
+
 // IsClosedConnection returns true if err is an error produced by gRPC on closed connections.
 func IsClosedConnection(err error) bool {
 	if err == context.Canceled || err == transport.ErrConnClosing || grpc.Code(err) == codes.Canceled {