Update develop branch

service/meta.go

@@ -0,0 +1,90 @@
+package service
+
+import (
+	"github.com/nspcc-dev/neofs-proto/internal"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+type (
+	// MetaHeader contains meta information of request.
+	// It provides methods to get or set meta information
+	// and reset meta header.
+	MetaHeader interface {
+		ResetMeta()
+
+		// TTLRequest to verify and update ttl requests.
+		GetTTL() uint32
+		SetTTL(uint32)
+
+		// EpochRequest gives possibility to get or set epoch in RPC Requests.
+		GetEpoch() uint64
+		SetEpoch(v uint64)
+	}
+
+	// TTLCondition is closure, that allows to validate request with ttl
+	TTLCondition func(ttl uint32) error
+)
+
+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
+)
+
+const (
+	// 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")
+)
+
+// SetTTL sets TTL to RequestMetaHeader
+func (m *RequestMetaHeader) SetTTL(v uint32) { m.TTL = v }
+
+// SetEpoch sets Epoch to RequestMetaHeader
+func (m *RequestMetaHeader) SetEpoch(v uint64) { m.Epoch = v }
+
+// ResetMeta sets RequestMetaHeader to empty value
+func (m *RequestMetaHeader) ResetMeta() { m.Reset() }
+
+// IRNonForwarding condition that allows NonForwardingTTL only for IR
+func IRNonForwarding(role NodeRole) TTLCondition {
+	return func(ttl uint32) error {
+		if ttl == NonForwardingTTL && role != InnerRingNode {
+			return ErrIncorrectTTL
+		}
+
+		return nil
+	}
+}
+
+// ProcessRequestTTL validates and update ttl requests.
+func ProcessRequestTTL(req MetaHeader, cond ...TTLCondition) error {
+	var ttl = req.GetTTL()
+
+	if ttl == ZeroTTL {
+		return status.New(codes.InvalidArgument, ErrZeroTTL.Error()).Err()
+	}
+
+	for i := range cond {
+		if cond[i] == nil {
+			continue
+		}
+
+		// check specific condition:
+		if err := cond[i](ttl); err != nil {
+			return status.New(codes.InvalidArgument, err.Error()).Err()
+		}
+	}
+
+	req.SetTTL(ttl - 1)
+
+	return nil
+}