From 88c67764b9515902514b0a8e4f00af29a353c584 Mon Sep 17 00:00:00 2001
From: Andrey Meshkov <am@adguard.com>
Date: Wed, 9 Sep 2020 18:12:11 +0300
Subject: [PATCH] * (dnsforward): don't fail when default upstream is not set

---
 dnsforward/config.go | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/dnsforward/config.go b/dnsforward/config.go
index c66406ac..5e4fe170 100644
--- a/dnsforward/config.go
+++ b/dnsforward/config.go
@@ -187,7 +187,7 @@ func (s *Server) createProxyConfig() (proxy.Config, error) {
 
 	// Validate proxy config
 	if proxyConfig.UpstreamConfig == nil || len(proxyConfig.UpstreamConfig.Upstreams) == 0 {
-		return proxyConfig, errors.New("no upstream servers configured")
+		return proxyConfig, errors.New("no default upstream servers configured")
 	}
 
 	return proxyConfig, nil
@@ -250,6 +250,16 @@ func (s *Server) prepareUpstreamSettings() error {
 	if err != nil {
 		return fmt.Errorf("DNS: proxy.ParseUpstreamsConfig: %s", err)
 	}
+
+	if len(upstreamConfig.Upstreams) == 0 {
+		log.Info("Warning: no default upstream servers specified, using %v", defaultDNS)
+		uc, err := proxy.ParseUpstreamsConfig(defaultDNS, s.conf.BootstrapDNS, DefaultTimeout)
+		if err != nil {
+			return fmt.Errorf("DNS: failed to parse default upstreams: %v", err)
+		}
+		upstreamConfig.Upstreams = uc.Upstreams
+	}
+
 	s.conf.UpstreamConfig = &upstreamConfig
 	return nil
 }