add upstream lookup for resolver

dns/resolver.go

@@ -5,6 +5,7 @@ import (
  "strings"
  "sync"
 
+ "github.com/gravitl/netclient/config"
  "github.com/miekg/dns"
  "golang.org/x/exp/slog"
 )
@@ -43,7 +44,24 @@ func handleDNSRequest(w dns.ResponseWriter, r *dns.Msg) {
  if resp != nil {
  reply.Answer = append(reply.Answer, resp)
  } else {
- reply.Rcode = dns.RcodeNameError
+ if config.Netclient().DNSManagerType != DNS_MANAGER_STUB {
+ client := &dns.Client{}
+ for _, v := range config.Netclient().NameServers {
+ resp, _, err := client.Exchange(r, v+":53")
+ if err != nil {
+ continue
+ }
+
+ if resp.Rcode != dns.RcodeSuccess {
+ continue
+ }
+
+ reply.Answer = append(reply.Answer, resp.Answer[0])
+ break
+ }
+ } else {
+ reply.Rcode = dns.RcodeNameError
+ }
  }
 
  err := w.WriteMsg(reply)