objectsvc: Make requestContextKey private

1. Disallow storing wrongly typed value by this key.
2. This is the way described in context.Value() documentation.

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

pkg/services/object/acl/v2/service.go

@@ -112,7 +112,7 @@ type wrappedGetObjectStream struct {
 }
 
 func (w *wrappedGetObjectStream) Context() context.Context {
-	return context.WithValue(w.GetObjectStream.Context(), object.RequestContextKey, &object.RequestContext{
+	return object.NewRequestContext(w.GetObjectStream.Context(), &object.RequestContext{
 		Namespace: w.requestInfo.ContainerNamespace(),
 		SenderKey: w.requestInfo.SenderKey(),
 		Role:      w.requestInfo.RequestRole(),
@@ -135,7 +135,7 @@ type wrappedRangeStream struct {
 }
 
 func (w *wrappedRangeStream) Context() context.Context {
-	return context.WithValue(w.GetObjectRangeStream.Context(), object.RequestContextKey, &object.RequestContext{
+	return object.NewRequestContext(w.GetObjectRangeStream.Context(), &object.RequestContext{
 		Namespace: w.requestInfo.ContainerNamespace(),
 		SenderKey: w.requestInfo.SenderKey(),
 		Role:      w.requestInfo.RequestRole(),
@@ -158,7 +158,7 @@ type wrappedSearchStream struct {
 }
 
 func (w *wrappedSearchStream) Context() context.Context {
-	return context.WithValue(w.SearchStream.Context(), object.RequestContextKey, &object.RequestContext{
+	return object.NewRequestContext(w.SearchStream.Context(), &object.RequestContext{
 		Namespace: w.requestInfo.ContainerNamespace(),
 		SenderKey: w.requestInfo.SenderKey(),
 		Role:      w.requestInfo.RequestRole(),
@@ -457,7 +457,7 @@ func (b Service) GetRange(request *objectV2.GetRangeRequest, stream object.GetOb
 }
 
 func requestContext(ctx context.Context, reqInfo RequestInfo) context.Context {
-	return context.WithValue(ctx, object.RequestContextKey, &object.RequestContext{
+	return object.NewRequestContext(ctx, &object.RequestContext{
 		Namespace: reqInfo.ContainerNamespace(),
 		SenderKey: reqInfo.SenderKey(),
 		Role:      reqInfo.RequestRole(),

pkg/services/object/ape/service.go

@@ -3,7 +3,6 @@ package ape
 import (
 	"context"
 	"encoding/hex"
-	"fmt"
 
 	objectV2 "git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/object"
 	"git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/refs"
@@ -88,25 +87,13 @@ func (g *getStreamBasicChecker) Send(resp *objectV2.GetResponse) error {
 	return g.GetObjectStream.Send(resp)
 }
 
-func requestContext(ctx context.Context) (*objectSvc.RequestContext, error) {
-	untyped := ctx.Value(objectSvc.RequestContextKey)
-	if untyped == nil {
-		return nil, fmt.Errorf("no key %s in context", objectSvc.RequestContextKey)
-	}
-	rc, ok := untyped.(*objectSvc.RequestContext)
-	if !ok {
-		return nil, fmt.Errorf("failed cast to RequestContext")
-	}
-	return rc, nil
-}
-
 func (c *Service) Get(request *objectV2.GetRequest, stream objectSvc.GetObjectStream) error {
 	cnrID, objID, err := getAddressParamsSDK(request.GetBody().GetAddress().GetContainerID(), request.GetBody().GetAddress().GetObjectID())
 	if err != nil {
 		return toStatusErr(err)
 	}
 
-	reqCtx, err := requestContext(stream.Context())
+	reqCtx, err := objectSvc.FromRequestContext(stream.Context())
 	if err != nil {
 		return toStatusErr(err)
 	}
@@ -137,7 +124,7 @@ type putStreamBasicChecker struct {
 
 func (p *putStreamBasicChecker) Send(ctx context.Context, request *objectV2.PutRequest) error {
 	if partInit, ok := request.GetBody().GetObjectPart().(*objectV2.PutObjectPartInit); ok {
-		reqCtx, err := requestContext(ctx)
+		reqCtx, err := objectSvc.FromRequestContext(ctx)
 		if err != nil {
 			return toStatusErr(err)
 		}
@@ -184,7 +171,7 @@ func (c *Service) Head(ctx context.Context, request *objectV2.HeadRequest) (*obj
 		return nil, err
 	}
 
-	reqCtx, err := requestContext(ctx)
+	reqCtx, err := objectSvc.FromRequestContext(ctx)
 	if err != nil {
 		return nil, err
 	}
@@ -248,7 +235,7 @@ func (c *Service) Search(request *objectV2.SearchRequest, stream objectSvc.Searc
 		}
 	}
 
-	reqCtx, err := requestContext(stream.Context())
+	reqCtx, err := objectSvc.FromRequestContext(stream.Context())
 	if err != nil {
 		return toStatusErr(err)
 	}
@@ -273,7 +260,7 @@ func (c *Service) Delete(ctx context.Context, request *objectV2.DeleteRequest) (
 		return nil, err
 	}
 
-	reqCtx, err := requestContext(ctx)
+	reqCtx, err := objectSvc.FromRequestContext(ctx)
 	if err != nil {
 		return nil, err
 	}
@@ -304,7 +291,7 @@ func (c *Service) GetRange(request *objectV2.GetRangeRequest, stream objectSvc.G
 		return toStatusErr(err)
 	}
 
-	reqCtx, err := requestContext(stream.Context())
+	reqCtx, err := objectSvc.FromRequestContext(stream.Context())
 	if err != nil {
 		return toStatusErr(err)
 	}
@@ -330,7 +317,7 @@ func (c *Service) GetRangeHash(ctx context.Context, request *objectV2.GetRangeHa
 		return nil, err
 	}
 
-	reqCtx, err := requestContext(ctx)
+	reqCtx, err := objectSvc.FromRequestContext(ctx)
 	if err != nil {
 		return nil, err
 	}
@@ -365,7 +352,7 @@ func (c *Service) PutSingle(ctx context.Context, request *objectV2.PutSingleRequ
 		return nil, err
 	}
 
-	reqCtx, err := requestContext(ctx)
+	reqCtx, err := objectSvc.FromRequestContext(ctx)
 	if err != nil {
 		return nil, err
 	}

pkg/services/object/request_context.go

@@ -1,10 +1,15 @@
 package object
 
-import "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/acl"
+import (
+	"context"
+	"fmt"
 
-type RequestContextKeyT struct{}
+	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/acl"
+)
 
-var RequestContextKey = RequestContextKeyT{}
+type requestContextKeyT struct{}
+
+var requestContextKey = requestContextKeyT{}
 
 // RequestContext is a context passed between middleware handlers.
 type RequestContext struct {
@@ -14,3 +19,17 @@ type RequestContext struct {
 
 	Role acl.Role
 }
+
+// NewRequestContext returns a copy of ctx which carries value.
+func NewRequestContext(ctx context.Context, value *RequestContext) context.Context {
+	return context.WithValue(ctx, requestContextKey, value)
+}
+
+// FromRequestContext returns RequestContext value stored in ctx if any.
+func FromRequestContext(ctx context.Context) (*RequestContext, error) {
+	reqCtx, ok := ctx.Value(requestContextKey).(*RequestContext)
+	if !ok {
+		return nil, fmt.Errorf("no key %s in context", requestContextKey)
+	}
+	return reqCtx, nil
+}