storage: add filter expressions, upgrade go to 1.18.1 (#3365)

* storage: add filter expressions

* upgrade go

pkg/storage/index.go

@@ -0,0 +1,65 @@
+package storage
+
+import (
+	"net/netip"
+
+	"google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/types/known/anypb"
+	"google.golang.org/protobuf/types/known/structpb"
+)
+
+const (
+	indexField = "$index"
+	cidrField  = "cidr"
+)
+
+// GetRecordIndex gets a record's index. If there is no index, nil is returned.
+func GetRecordIndex(msg proto.Message) *structpb.Struct {
+	for {
+		any, ok := msg.(*anypb.Any)
+		if !ok {
+			break
+		}
+		msg, _ = any.UnmarshalNew()
+	}
+
+	var s *structpb.Struct
+	if sv, ok := msg.(*structpb.Value); ok {
+		s = sv.GetStructValue()
+	} else {
+		s, _ = msg.(*structpb.Struct)
+	}
+	if s == nil {
+		return nil
+	}
+
+	f, ok := s.Fields[indexField]
+	if !ok {
+		return nil
+	}
+	return f.GetStructValue()
+}
+
+// GetRecordIndexCIDR returns the $index.cidr for a record's data. If none is available nil is returned.
+func GetRecordIndexCIDR(msg proto.Message) *netip.Prefix {
+	obj := GetRecordIndex(msg)
+	if obj == nil {
+		return nil
+	}
+
+	cf, ok := obj.Fields[cidrField]
+	if !ok {
+		return nil
+	}
+
+	c := cf.GetStringValue()
+	if c == "" {
+		return nil
+	}
+
+	prefix, err := netip.ParsePrefix(c)
+	if err != nil {
+		return nil
+	}
+	return &prefix
+}