Fixing issue #5376 by adding a check to parse out Zone info (#5387)

* Fixing #5376 by adding a check to parse out Zone information
Signed-off-by: Tintin <samrath.sodi@gmail.com>

* using IndexByte instead of strings.Split()
Signed-off-by: Tintin <samrath.sodi@gmail.com>

* using plugin logger for logging parsing failure
Signed-off-by: Tintin <samrath.sodi@gmail.com>

* using var keywork instead of short declaration operator
Signed-off-by: Tintin <samrath.sodi@gmail.com>

* reordering imports
Signed-off-by: Tintin <samrath.sodi@gmail.com>

plugin/acl/acl.go

@@ -3,9 +3,11 @@ package acl
 import (
 	"context"
 	"net"
+	"strings"
 
 	"github.com/coredns/coredns/plugin"
 	"github.com/coredns/coredns/plugin/metrics"
+	clog "github.com/coredns/coredns/plugin/pkg/log"
 	"github.com/coredns/coredns/request"
 
 	"github.com/infobloxopen/go-trees/iptree"
@@ -49,6 +51,8 @@ const (
 	actionFilter
 )
 
+var log = clog.NewWithPlugin("acl")
+
 // ServeDNS implements the plugin.Handler interface.
 func (a ACL) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
 	state := request.Request{W: w, Req: r}
@@ -96,7 +100,19 @@ RulesCheckLoop:
 func matchWithPolicies(policies []policy, w dns.ResponseWriter, r *dns.Msg) action {
 	state := request.Request{W: w, Req: r}
 
-	ip := net.ParseIP(state.IP())
+	var ip net.IP
+	if idx := strings.IndexByte(state.IP(), '%'); idx >= 0 {
+		ip = net.ParseIP(state.IP()[:idx])
+	} else {
+		ip = net.ParseIP(state.IP())
+	}
+
+	// if the parsing did not return a proper response then we simply return 'actionBlock' to
+	// block the query
+	if ip == nil {
+		log.Errorf("Blocking request. Unable to parse source address: %v", state.IP())
+		return actionBlock
+	}
 	qtype := state.QType()
 	for _, policy := range policies {
 		// dns.TypeNone matches all query types.

plugin/acl/acl_test.go

@@ -19,6 +19,10 @@ func (t *testResponseWriter) setRemoteIP(ip string) {
 	t.RemoteIP = ip
 }
 
+func (t *testResponseWriter) setZone(zone string) {
+	t.Zone = zone
+}
+
 // WriteMsg implement dns.ResponseWriter interface.
 func (t *testResponseWriter) WriteMsg(m *dns.Msg) error {
 	t.Rcode = m.Rcode
@@ -392,6 +396,20 @@ func TestACLServeDNS(t *testing.T) {
 			dns.RcodeSuccess,
 			false,
 		},
+		{
+			"Blacklist Address%ifname",
+			`acl example.org {
+				block type AAAA net 2001:0db8:85a3:0000:0000:8a2e:0370:7334
+			}`,
+			[]string{"eth0"},
+			args{
+				"www.example.org.",
+				"2001:0db8:85a3:0000:0000:8a2e:0370:7334",
+				dns.TypeAAAA,
+			},
+			dns.RcodeRefused,
+			false,
+		},
 	}
 
 	ctx := context.Background()
@@ -408,6 +426,9 @@ func TestACLServeDNS(t *testing.T) {
 			w := &testResponseWriter{}
 			m := new(dns.Msg)
 			w.setRemoteIP(tt.args.sourceIP)
+			if len(tt.zones) > 0 {
+				w.setZone(tt.zones[0])
+			}
 			m.SetQuestion(tt.args.domain, tt.args.qtype)
 			_, err = a.ServeDNS(ctx, w, m)
 			if (err != nil) != tt.wantErr {

plugin/test/responsewriter.go

@@ -12,6 +12,7 @@ import (
 type ResponseWriter struct {
 	TCP      bool // if TCP is true we return an TCP connection instead of an UDP one.
 	RemoteIP string
+	Zone     string
 }
 
 // LocalAddr returns the local address, 127.0.0.1:53 (UDP, TCP if t.TCP is true).
@@ -33,9 +34,9 @@ func (t *ResponseWriter) RemoteAddr() net.Addr {
 	ip := net.ParseIP(remoteIP)
 	port := 40212
 	if t.TCP {
-		return &net.TCPAddr{IP: ip, Port: port, Zone: ""}
+		return &net.TCPAddr{IP: ip, Port: port, Zone: t.Zone}
 	}
-	return &net.UDPAddr{IP: ip, Port: port, Zone: ""}
+	return &net.UDPAddr{IP: ip, Port: port, Zone: t.Zone}
 }
 
 // WriteMsg implements dns.ResponseWriter interface.