fixed issues found by go-fuzz

filter.go

@@ -102,6 +102,9 @@ func NewQuery(s string, l Logic) (q *Query, err error) {
 					switch s[2] {
 					case asc, desc:
 						q.s.fields = strings.Split(s[1], ".")
+						if err = checkFields(q.s.fields, v); err != nil {
+							return
+						}
 						if len(q.s.fields) > 0 {
 							if s[2] == desc {
 								q.s.desc = true
@@ -129,8 +132,12 @@ func NewQuery(s string, l Logic) (q *Query, err error) {
 			}
 			qm[m[0]] = struct{}{}
 		}
+		mf := strings.Split(m[0], ".")
+		if err = checkFields(mf, m[0]); err != nil {
+			return
+		}
 		q.m = append(q.m, match{
-			strings.Split(m[0], "."),
+			mf,
 			matchFunc(m[1]),
 			boolFunc(m[1]),
 		})
@@ -191,9 +198,9 @@ func (q *Query) match(v reflect.Value) (ok bool) {
 		if fl == 0 {
 			continue
 		}
-		val := v.FieldByName(qv.fields[0])
-		for j := 1; j < fl; j++ {
-			val = val.FieldByName(qv.fields[j])
+		val := walkFields(v.FieldByName(qv.fields[0]), qv.fields[1:])
+		if val.Kind() == reflect.Invalid {
+			continue
 		}
 		s, b, err := getValue(val)
 		if err != nil {
@@ -239,6 +246,9 @@ func (q Query) sort(f Filter) {
 		return
 	}
 	l := makeLess(f, q.s.fields)
+	if l == nil {
+		return
+	}
 	if q.s.desc {
 		l = reverse(l)
 	}