[#350] object/acl: Make best effort to classify request

Classifier looks at list of inner ring nodes and container
nodes from current and previous epoch to classify request.
Sometimes these checks might return error.

Consider there is a request from unknown key and container's
placement policy valid for current epoch and invalid for past
epoch. Classifier tries to find if key belongs to container
node from current epoch -- it is not. Then it tries to find if
key belongs to container node from past epoch and it throws
error, because placement policy is invalid for past epoch.

This is a legit case and classifier should ignore such errors
to provide best effort in matching. The only error classifier
should return is an error when request does not contain
public key to classify it.

Signed-off-by: Alex Vanin <alexey@nspcc.ru>

cmd/neofs-node/object.go

@@ -287,6 +287,7 @@ func initObjectService(c *cfg) {
 			acl.New(
 				acl.WithSenderClassifier(
 					acl.NewSenderClassifier(
+						c.log,
 						c.cfgNetmap.wrapper,
 						c.cfgNetmap.wrapper,
 					),

pkg/services/object/acl/classifier.go

@@ -16,6 +16,7 @@ import (
 	crypto "github.com/nspcc-dev/neofs-crypto"
 	core "github.com/nspcc-dev/neofs-node/pkg/core/netmap"
 	"github.com/pkg/errors"
+	"go.uber.org/zap"
 )
 
 type (
@@ -31,14 +32,16 @@ type (
 	}
 
 	SenderClassifier struct {
+		log       *zap.Logger
 		innerRing InnerRingFetcher
 		netmap    core.Source
 	}
 )
 
 // fixme: update classifier constructor
-func NewSenderClassifier(ir InnerRingFetcher, nm core.Source) SenderClassifier {
+func NewSenderClassifier(l *zap.Logger, ir InnerRingFetcher, nm core.Source) SenderClassifier {
 	return SenderClassifier{
+		log:       l,
 		innerRing: ir,
 		netmap:    nm,
 	}
@@ -68,14 +71,20 @@ func (c SenderClassifier) Classify(
 
 	isInnerRingNode, err := c.isInnerRingKey(ownerKeyInBytes)
 	if err != nil {
-		return 0, false, nil, errors.Wrap(err, "can't check if request from inner ring")
+		// do not throw error, try best case matching
+		c.log.Debug("can't check if request from inner ring",
+			zap.String("error", err.Error()))
 	} else if isInnerRingNode {
 		return acl.RoleSystem, true, ownerKeyInBytes, nil
 	}
 
 	isContainerNode, err := c.isContainerKey(ownerKeyInBytes, cid.ToV2().GetValue(), cnr)
 	if err != nil {
-		return 0, false, nil, errors.Wrap(err, "can't check if request from container node")
+		// error might happen if request has `RoleOther` key and placement
+		// is not possible for previous epoch, so
+		// do not throw error, try best case matching
+		c.log.Debug("can't check if request from container node",
+			zap.String("error", err.Error()))
 	} else if isContainerNode {
 		return acl.RoleSystem, false, ownerKeyInBytes, nil
 	}