func guessIsLoginSTSReq(req *http.Request) bool {
	if req == nil {
		return false
	}
	return strings.HasPrefix(req.URL.Path, loginPathPrefix) ||
		(req.Method == http.MethodPost && req.URL.Path == SlashSeparator &&
			getRequestAuthType(req) == authTypeSTS)

	minioReservedBucket     = "minio"
	minioReservedBucketPath = SlashSeparator + minioReservedBucket

	loginPathPrefix = SlashSeparator + "login"
)

func guessIsBrowserReq(r *http.Request) bool {
	aType := getRequestAuthType(r)
	return strings.Contains(r.Header.Get("User-Agent"), "Mozilla") &&
		globalBrowserEnabled && aType == authTypeAnonymous
}

func setBrowserRedirectMiddleware(h http.Handler) http.Handler {

	// type to return the correct error (NoSuchKey vs AccessDenied)
	if s3Error := checkRequestAuthType(ctx, r, policy.GetObjectAction, bucket, zipPath); s3Error != ErrNone {
		if getRequestAuthType(r) == authTypeAnonymous {
			// As per "Permission" section in
			// https://docs.aws.amazon.com/AmazonS3/latest/API/RESTObjectGET.html
			// If the object you request does not exist,

	authTypeSigned
	authTypeSignedV2
	authTypeJWT
	authTypeSTS
	authTypeStreamingSignedTrailer
	authTypeStreamingUnsignedTrailer
)

// Get request authentication type.
func getRequestAuthType(r *http.Request) (at authType) {
	if r.URL != nil {
		var err error
		r.Form, err = url.ParseQuery(r.URL.RawQuery)
		if err != nil {
			authNLogIf(r.Context(), err)
			return authTypeUnknown
		}
	}

	}

	vid := r.Form.Get(xhttp.VersionID)
	if vid == "" {
		if u, err := url.Parse(r.Header.Get(xhttp.AmzCopySource)); err == nil {
			vid = u.Query().Get(xhttp.VersionID)
		}
	}

	authType := getRequestAuthType(r)
	var signatureVersion string
	switch authType {
	case authTypeSignedV2, authTypePresignedV2:
		signatureVersion = signV2Algorithm

	srcInfo.UserDefined = objectlock.FilterObjectLockMetadata(srcInfo.UserDefined, true, true)
	retPerms := isPutActionAllowed(ctx, getRequestAuthType(r), dstBucket, dstObject, r, policy.PutObjectRetentionAction)
	holdPerms := isPutActionAllowed(ctx, getRequestAuthType(r), dstBucket, dstObject, r, policy.PutObjectLegalHoldAction)
	getObjectInfo := objectAPI.GetObjectInfo

		metadata[ReservedMetadataPrefixLower+ReplicaTimestamp] = UTCNow().Format(time.RFC3339Nano)
	}
	retPerms := isPutActionAllowed(ctx, getRequestAuthType(r), bucket, object, r, policy.PutObjectRetentionAction)
	holdPerms := isPutActionAllowed(ctx, getRequestAuthType(r), bucket, object, r, policy.PutObjectLegalHoldAction)

	getObjectInfo := objectAPI.GetObjectInfo

				},
				Method: http.MethodPost,
				Body:   nopCloser,
			},
			authT: authTypePostPolicy,
		},
	}

	// .. Tests all request auth type.
	for i, testc := range testCases {
		authT := getRequestAuthType(testc.req)
		if authT != testc.authT {
			t.Errorf("Test %d: Expected %d, got %d", i+1, testc.authT, authT)
		}
	}
}

// Test all s3 supported auth types.
func TestS3SupportedAuthType(t *testing.T) {