From 94552a30d7080c8471f7fca370a5905c6c420272 Mon Sep 17 00:00:00 2001 From: Simon Zolin Date: Tue, 20 Aug 2019 14:46:09 +0300 Subject: [PATCH] - dnsforward: don't use dnsfilter object after it's closed --- dnsforward/dnsforward.go | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/dnsforward/dnsforward.go b/dnsforward/dnsforward.go index 0f587cbb..b8a8afd1 100644 --- a/dnsforward/dnsforward.go +++ b/dnsforward/dnsforward.go @@ -451,7 +451,15 @@ func (s *Server) handleDNSRequest(p *proxy.Proxy, d *proxy.DNSContext) error { } // use dnsfilter before cache -- changed settings or filters would require cache invalidation otherwise + s.RLock() + // Synchronize access to s.dnsFilter so it won't be suddenly uninitialized while in use. + // This could happen after proxy server has been stopped, but its workers are not yet exited. + // + // A better approach is for proxy.Stop() to wait until all its workers exit, + // but this would require the Upstream interface to have Close() function + // (to prevent from hanging while waiting for unresponsive DNS server to respond). res, err := s.filterDNSRequest(d) + s.RUnlock() if err != nil { return err } @@ -511,21 +519,13 @@ func (s *Server) filterDNSRequest(d *proxy.DNSContext) (*dnsfilter.Result, error var res dnsfilter.Result req := d.Req host := strings.TrimSuffix(req.Question[0].Name, ".") - origHost := host - s.RLock() - protectionEnabled := s.conf.ProtectionEnabled dnsFilter := s.dnsFilter - s.RUnlock() - if !protectionEnabled { + if !s.conf.ProtectionEnabled { return &dnsfilter.Result{}, nil } - if host != origHost { - log.Debug("Rewrite: not supported: CNAME for %s is %s", origHost, host) - } - var err error clientAddr := ""