Validate zone during normalization (#3165)

core/dnsserver/address.go

@@ -3,6 +3,7 @@ package dnsserver
 import (
 	"fmt"
 	"net"
+	"net/url"
 	"strings"
 
 	"github.com/coredns/coredns/plugin"
@@ -52,7 +53,13 @@ func normalizeZone(str string) (zoneAddr, error) {
 		}
 	}
 
-	return zoneAddr{Zone: dns.Fqdn(host), Port: port, Transport: trans, IPNet: ipnet}, nil
+	z := zoneAddr{Zone: dns.Fqdn(host), Port: port, Transport: trans, IPNet: ipnet}
+	_, err = url.ParseRequestURI(z.String())
+	if err != nil {
+		return zoneAddr{}, err
+	}
+
+	return z, nil
 }
 
 // SplitProtocolHostPort splits a full formed address like "dns://[::1]:53" into parts.

core/dnsserver/address_test.go

@@ -28,6 +28,7 @@ func TestNormalizeZone(t *testing.T) {
 		{"https://.:8443", "https://.:8443", false},
 		{"https://..", "://:", true},
 		{"https://.:", "://:", true},
+		{"dns://.:1053{.:53", "://:", true},
 	} {
 		addr, err := normalizeZone(test.input)
 		actual := addr.String()