[#872] object: Introduce APE middlewar for object service

Signed-off-by: Airat Arifullin <a.arifullin@yadro.com>

pkg/services/object/ape/checker.go

@@ -0,0 +1,82 @@
+package ape
+
+import (
+	"context"
+	"fmt"
+
+	objectV2 "git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/object"
+	apistatus "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/client/status"
+	cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
+	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
+	apechain "git.frostfs.info/TrueCloudLab/policy-engine/pkg/chain"
+	policyengine "git.frostfs.info/TrueCloudLab/policy-engine/pkg/engine"
+)
+
+type checkerImpl struct {
+	chainRouter policyengine.ChainRouter
+
+	headerProvider HeaderProvider
+}
+
+func NewChecker(chainRouter policyengine.ChainRouter, headerProvider HeaderProvider) Checker {
+	return &checkerImpl{
+		chainRouter: chainRouter,
+
+		headerProvider: headerProvider,
+	}
+}
+
+type Prm struct {
+	Namespace string
+
+	Container cid.ID
+
+	// Object ID is omitted for some methods.
+	Object *oid.ID
+
+	// If Header is set, then object attributes and properties will be parsed from
+	// a request/response's header.
+	Header *objectV2.Header
+
+	// Method must be represented only as a constant represented in native schema.
+	Method string
+
+	// Role must be representedonly as a constant represented in native schema.
+	Role string
+
+	// An encoded sender's public key string.
+	SenderKey string
+}
+
+var (
+	errMissingOID = fmt.Errorf("object ID is not set")
+)
+
+// CheckAPE checks if a request or a response is permitted creating an ape request and passing
+// it to chain router.
+func (c *checkerImpl) CheckAPE(ctx context.Context, prm Prm) error {
+	r, err := c.newAPERequest(ctx, prm)
+	if err != nil {
+		return fmt.Errorf("failed to create ape request: %w", err)
+	}
+
+	status, ruleFound, err := c.chainRouter.IsAllowed(apechain.Ingress,
+		policyengine.NewRequestTarget(prm.Namespace, prm.Container.EncodeToString()), r)
+	if err != nil {
+		return err
+	}
+
+	if !ruleFound || status == apechain.Allow {
+		return nil
+	}
+
+	return apeErr(prm.Method, status)
+}
+
+const accessDeniedAPEReasonFmt = "access to operation %s is denied by access policy engine: %s"
+
+func apeErr(op string, status apechain.Status) error {
+	errAccessDenied := &apistatus.ObjectAccessDenied{}
+	errAccessDenied.WriteReason(fmt.Sprintf(accessDeniedAPEReasonFmt, op, status.String()))
+	return errAccessDenied
+}