dnsforward: imp code

internal/dnsforward/filter.go

@@ -95,7 +95,7 @@ func (s *Server) filterDNSRequest(dctx *dnsContext) (res *filtering.Result, err
 		dctx.origQuestion = q
 		req.Question[0].Name = dns.Fqdn(res.CanonName)
 	case res.Reason == filtering.Rewritten:
-		pctx.Res = s.filterRewritten(req, host, res, q.Qtype)
+		pctx.Res = s.getCNAMEWithIPs(req, res.IPList, res.CanonName)
 	case res.Reason.In(filtering.RewrittenRule, filtering.RewrittenAutoHosts):
 		if err = s.filterDNSRewrite(req, res, pctx); err != nil {
 			return nil, err
@@ -105,37 +105,6 @@ func (s *Server) filterDNSRequest(dctx *dnsContext) (res *filtering.Result, err
 	return res, err
 }
 
-// filterRewritten handles DNS rewrite filters.  It returns a DNS response with
-// the data from the filtering result.  All parameters must not be nil.
-func (s *Server) filterRewritten(
-	req *dns.Msg,
-	host string,
-	res *filtering.Result,
-	qt uint16,
-) (resp *dns.Msg) {
-	resp = s.makeResponse(req)
-	name := host
-	if len(res.CanonName) != 0 {
-		resp.Answer = append(resp.Answer, s.genAnswerCNAME(req, res.CanonName))
-		name = res.CanonName
-	}
-
-	for _, ip := range res.IPList {
-		switch qt {
-		case dns.TypeA:
-			a := s.genAnswerA(req, ip)
-			a.Hdr.Name = dns.Fqdn(name)
-			resp.Answer = append(resp.Answer, a)
-		case dns.TypeAAAA:
-			a := s.genAnswerAAAA(req, ip)
-			a.Hdr.Name = dns.Fqdn(name)
-			resp.Answer = append(resp.Answer, a)
-		}
-	}
-
-	return resp
-}
-
 // checkHostRules checks the host against filters.  It is safe for concurrent
 // use.
 func (s *Server) checkHostRules(

internal/dnsforward/msg.go

@@ -66,15 +66,17 @@ func (s *Server) genDNSFilterMessage(
 		// If Safe Search generated the necessary IP addresses, use them.
 		// Otherwise, if there were no errors, there are no addresses for the
 		// requested IP version, so produce a NODATA response.
-		return s.genFltSafeSearch(req, ipsFromRules(res.Rules), res.CanonName)
+		return s.getCNAMEWithIPs(req, ipsFromRules(res.Rules), res.CanonName)
 	default:
 		return s.genForBlockingMode(req, ipsFromRules(res.Rules))
 	}
 }
 
-// genFltSafeSearch generates a filtered response to req for safe search filter.
-// Adds a CNAME record if cname if provided.
-func (s *Server) genFltSafeSearch(req *dns.Msg, ips []netip.Addr, cname string) (resp *dns.Msg) {
+// getCNAMEWithIPs generates a filtered response to req for with CNAME record
+// and provided ips.
+func (s *Server) getCNAMEWithIPs(req *dns.Msg, ips []netip.Addr, cname string) (resp *dns.Msg) {
+	resp = s.makeResponse(req)
+
 	originalName := req.Question[0].Name
 
 	var ans []dns.RR
@@ -83,6 +85,7 @@ func (s *Server) genFltSafeSearch(req *dns.Msg, ips []netip.Addr, cname string)
 
 		// The given IPs actually are resolved for this cname.
 		req.Question[0].Name = dns.Fqdn(cname)
+		defer func() { req.Question[0].Name = originalName }()
 	}
 
 	switch req.Question[0].Qtype {
@@ -98,9 +101,6 @@ func (s *Server) genFltSafeSearch(req *dns.Msg, ips []netip.Addr, cname string)
 		// Go on and return an empty response.
 	}
 
-	req.Question[0].Name = originalName
-
-	resp = s.makeResponse(req)
 	resp.Answer = ans
 
 	return resp