initial

service/ttl.go

@@ -0,0 +1,45 @@
+package service
+
+import (
+	"github.com/nspcc-dev/neofs-proto/internal"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+// TTLRequest to verify and update ttl requests.
+type TTLRequest interface {
+	GetTTL() uint32
+	SetTTL(uint32)
+}
+
+const (
+	// ZeroTTL is empty ttl, should produce ErrZeroTTL.
+	ZeroTTL = iota
+
+	// NonForwardingTTL is a ttl that allows direct connections only.
+	NonForwardingTTL
+
+	// SingleForwardingTTL is a ttl that allows connections through another node.
+	SingleForwardingTTL
+
+	// ErrZeroTTL is raised when zero ttl is passed.
+	ErrZeroTTL = internal.Error("zero ttl")
+
+	// ErrIncorrectTTL is raised when NonForwardingTTL is passed and NodeRole != InnerRingNode.
+	ErrIncorrectTTL = internal.Error("incorrect ttl")
+)
+
+// CheckTTLRequest validates and update ttl requests.
+func CheckTTLRequest(req TTLRequest, role NodeRole) error {
+	var ttl = req.GetTTL()
+
+	if ttl == ZeroTTL {
+		return status.New(codes.InvalidArgument, ErrZeroTTL.Error()).Err()
+	} else if ttl == NonForwardingTTL && role != InnerRingNode {
+		return status.New(codes.InvalidArgument, ErrIncorrectTTL.Error()).Err()
+	}
+
+	req.SetTTL(ttl - 1)
+
+	return nil
+}