plugin/rewrite: add handling of TTL field rewrites (#2048)

Resolves: #1981

Signed-off-by: Paul Greenberg <greenpau@outlook.com>

1 files changed, 10 insertions, 9 deletions

diff --git a/plugin/rewrite/rewrite.go b/plugin/rewrite/rewrite.go
index 643f2d7c9..64283df92 100644
--- a/plugin/rewrite/rewrite.go
+++ b/plugin/rewrite/rewrite.go
@@ -50,7 +50,6 @@ func (rw Rewrite) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg
 				state.Req.Question[0] = wr.originalQuestion
 				return dns.RcodeServerFailure, fmt.Errorf("invalid name after rewrite: %s", x)
 			}
-
 			respRule := rule.GetResponseRule()
 			if respRule.Active == true {
 				wr.ResponseRewrite = true
@@ -111,23 +110,25 @@ func newRule(args ...string) (Rule, error) {
 		startArg = 1
 	}
 
-	if ruleType == "answer" {
-		return nil, fmt.Errorf("response rewrites must begin with a name rule")
-	}
-
-	if ruleType != "edns0" && ruleType != "name" && expectNumArgs != 3 {
-		return nil, fmt.Errorf("%s rules must have exactly two arguments", ruleType)
-	}
-
 	switch ruleType {
+	case "answer":
+		return nil, fmt.Errorf("response rewrites must begin with a name rule")
 	case "name":
 		return newNameRule(mode, args[startArg:]...)
 	case "class":
+		if expectNumArgs != 3 {
+			return nil, fmt.Errorf("%s rules must have exactly two arguments", ruleType)
+		}
 		return newClassRule(mode, args[startArg:]...)
 	case "type":
+		if expectNumArgs != 3 {
+			return nil, fmt.Errorf("%s rules must have exactly two arguments", ruleType)
+		}
 		return newTypeRule(mode, args[startArg:]...)
 	case "edns0":
 		return newEdns0Rule(mode, args[startArg:]...)
+	case "ttl":
+		return newTtlRule(mode, args[startArg:]...)
 	default:
 		return nil, fmt.Errorf("invalid rule type %q", args[0])
 	}