fix issue where search domains are ignored

This commit fixes an issue where search domains was ignored
if the user has not configured any external resolvers. Based
on tailscale's documentation, there is no mention of this
behaviour as far as I can see:
https://tailscale.com/kb/1054/dns#search-domains

In addition, it does add the missing base domain to the
search domain.

Signed-off-by: Kristoffer Dalby <[email protected]>

hscontrol/types/config.go

@@ -536,16 +536,6 @@ func GetDNSConfig() (*tailcfg.DNSConfig, string) {
 			dnsConfig.Domains = domains
 		}
 
-		if viper.IsSet("dns_config.domains") {
-			domains := viper.GetStringSlice("dns_config.domains")
-			if len(dnsConfig.Resolvers) > 0 {
-				dnsConfig.Domains = domains
-			} else if domains != nil {
-				log.Warn().
-					Msg("Warning: dns_config.domains is set, but no nameservers are configured. Ignoring domains.")
-			}
-		}
-
 		if viper.IsSet("dns_config.extra_records") {
 			var extraRecords []tailcfg.DNSRecord
 
@@ -571,8 +561,11 @@ func GetDNSConfig() (*tailcfg.DNSConfig, string) {
 			baseDomain = "headscale.net" // does not really matter when MagicDNS is not enabled
 		}
 
-		log.Trace().Interface("dns_config", dnsConfig).Msg("DNS configuration loaded")
+		if domains := viper.GetStringSlice("dns_config.domains"); len(domains) > 0 {
+			dnsConfig.Domains = append(dnsConfig.Domains, domains...)
+		}
 
+		log.Trace().Interface("dns_config", dnsConfig).Msg("DNS configuration loaded")
 		return dnsConfig, baseDomain
 	}