Adds root context for dns resolution timeout, set to 100 times the upstream timeout duration

resolver/custom_dns_resolver.go

@@ -92,6 +92,9 @@ func (r *CustomDNSResolver) processRequest(ctx context.Context, request *model.R
 	domain := util.ExtractDomain(question)
 
 	for len(domain) > 0 {
+		if err := ctx.Err(); err != nil {
+			return nil, err
+		}
 		entries, found := r.mapping[domain]
 		if found {
 			for _, entry := range entries {

server/server.go

@@ -611,6 +611,8 @@ func (s *Server) OnRequest(
 
 func (s *Server) resolve(ctx context.Context, request *model.Request) (*model.Response, error) {
 	var response *model.Response
+	ctx, cancel := context.WithTimeout(ctx, 100*s.cfg.Upstreams.Timeout.ToDuration())
+	defer cancel()
 
 	switch {
 	case len(request.Req.Question) == 0: