Limit $GENERATE range to 65535 steps

Fixes #1019

Signed-off-by: Miek Gieben <[email protected]>

generate.go

@@ -56,7 +56,7 @@ func (zp *ZoneParser) generate(l lex) (RR, bool) {
 	// _BLANK
 	l, ok := zp.c.Next()
 	if !ok || l.value != zBlank {
-			return zp.setParseError("garbage after $GENERATE range", l)
+		return zp.setParseError("garbage after $GENERATE range", l)
 	}
 
 	// Create a complete new string, which we then parse again.
@@ -72,6 +72,10 @@ func (zp *ZoneParser) generate(l lex) (RR, bool) {
 		s += l.token
 	}
 
+	if (end-start)/step > 65536 {
+		return zp.setParseError("bad range in $GENERATE directive", l)
+	}
+
 	r := &generateReader{
 		s: s,
 

generate_test.go

@@ -205,13 +205,11 @@ $GENERATE 32-158 dhcp-${-32,4,d} A 10.0.0.$
 	}
 }
 
-
-
 func TestCrasherString(t *testing.T) {
-	tests := []struct{
-	in  string
-	err string
-}{
+	tests := []struct {
+		in  string
+		err string
+	}{
 		{"$GENERATE 0-300103\"$$GENERATE 2-2", "dns: garbage after $GENERATE range: \"\\\"\" at line: 1:19"},
 		{"$GENERATE 0-5414137360", "dns: garbage after $GENERATE range: \"\\n\" at line: 1:22"},
 		{"$GENERATE       11522-3668518066406258", "dns: garbage after $GENERATE range: \"\\n\" at line: 1:38"},
@@ -229,3 +227,32 @@ func TestCrasherString(t *testing.T) {
 		})
 	}
 }
+
+func TestOutofRangeRange(t *testing.T) {
+	// outside limit
+	data := `$GENERATE 0-65537 dhcp A 10.0.0.1`
+	zp := NewZoneParser(strings.NewReader(data), ".", "test")
+	for _, ok := zp.Next(); ok; _, ok = zp.Next() {
+	}
+	if !strings.Contains(zp.Err().Error(), "dns: bad range in $GENERATE directive:") {
+		t.Errorf("Expected %q error, got %s", "bad range", zp.Err())
+	}
+
+	// within limit
+	data = `$GENERATE 0-65535 dhcp A 10.0.0.1`
+	zp = NewZoneParser(strings.NewReader(data), ".", "test")
+	for _, ok := zp.Next(); ok; _, ok = zp.Next() {
+	}
+	if zp.Err() != nil {
+		t.Errorf("Expected nil error, got %s", zp.Err())
+	}
+
+	// within limit, due to /2
+	data = `$GENERATE 0-65537/2 dhcp A 10.0.0.1`
+	zp = NewZoneParser(strings.NewReader(data), ".", "test")
+	for _, ok := zp.Next(); ok; _, ok = zp.Next() {
+	}
+	if zp.Err() != nil {
+		t.Errorf("Expected nil error, got %s", zp.Err())
+	}
+}