zitadel/internal/api/oidc/auth_request.go
Tim Möhlmann 8e0c8393e9
perf(oidc): optimize token creation (#7822)
* implement code exchange

* port tokenexchange to v2 tokens

* implement refresh token

* implement client credentials

* implement jwt profile

* implement device token

* cleanup unused code

* fix current unit tests

* add user agent unit test

* unit test domain package

* need refresh token as argument

* test commands create oidc session

* test commands device auth

* fix device auth build error

* implicit for oidc session API

* implement authorize callback handler for legacy implicit mode

* upgrade oidc module to working draft

* add missing auth methods and time

* handle all errors in defer

* do not fail auth request on error

the oauth2 Go client automagically retries on any error. If we fail the auth request on the first error, the next attempt will always fail with the Errors.AuthRequest.NoCode, because the auth request state is already set to failed.
The original error is then already lost and the oauth2 library does not return the original error.

Therefore we should not fail the auth request.

Might be worth discussing and perhaps send a bug report to Oauth2?

* fix code flow tests by explicitly setting code exchanged

* fix unit tests in command package

* return allowed scope from client credential client

* add device auth done reducer

* carry nonce thru session into ID token

* fix token exchange integration tests

* allow project role scope prefix in client credentials client

* gci formatting

* do not return refresh token in client credentials and jwt profile

* check org scope

* solve linting issue on authorize callback error

* end session based on v2 session ID

* use preferred language and user agent ID for v2 access tokens

* pin oidc v3.23.2

* add integration test for jwt profile and client credentials with org scopes

* refresh token v1 to v2

* add user token v2 audit event

* add activity trigger

* cleanup and set panics for unused methods

* use the encrypted code for v1 auth request get by code

* add missing event translation

* fix pipeline errors (hopefully)

* fix another test

* revert pointer usage of preferred language

* solve browser info panic in device auth

* remove duplicate entries in AMRToAuthMethodTypes to prevent future `mfa` claim

* revoke v1 refresh token to prevent reuse

* fix terminate oidc session

* always return a new refresh toke in refresh token grant

---------

Co-authored-by: Livio Spring <livio.a@gmail.com>
2024-05-16 07:07:56 +02:00

609 lines
20 KiB
Go

package oidc
import (
"context"
"encoding/base64"
"fmt"
"net/http"
"slices"
"strings"
"time"
"github.com/zitadel/logging"
"github.com/zitadel/oidc/v3/pkg/oidc"
"github.com/zitadel/oidc/v3/pkg/op"
"golang.org/x/text/language"
"github.com/zitadel/zitadel/internal/api/authz"
http_utils "github.com/zitadel/zitadel/internal/api/http"
"github.com/zitadel/zitadel/internal/api/http/middleware"
"github.com/zitadel/zitadel/internal/command"
"github.com/zitadel/zitadel/internal/domain"
"github.com/zitadel/zitadel/internal/query"
"github.com/zitadel/zitadel/internal/telemetry/tracing"
"github.com/zitadel/zitadel/internal/user/model"
"github.com/zitadel/zitadel/internal/zerrors"
)
const (
LoginClientHeader = "x-zitadel-login-client"
)
func (o *OPStorage) CreateAuthRequest(ctx context.Context, req *oidc.AuthRequest, userID string) (_ op.AuthRequest, err error) {
ctx, span := tracing.NewSpan(ctx)
defer func() {
err = oidcError(err)
span.EndWithError(err)
}()
headers, _ := http_utils.HeadersFromCtx(ctx)
if loginClient := headers.Get(LoginClientHeader); loginClient != "" {
return o.createAuthRequestLoginClient(ctx, req, userID, loginClient)
}
return o.createAuthRequest(ctx, req, userID)
}
func (o *OPStorage) createAuthRequestScopeAndAudience(ctx context.Context, clientID string, reqScope []string) (scope, audience []string, err error) {
project, err := o.query.ProjectByClientID(ctx, clientID)
if err != nil {
return nil, nil, err
}
scope, err = o.assertProjectRoleScopesByProject(ctx, project, reqScope)
if err != nil {
return nil, nil, err
}
audience, err = o.audienceFromProjectID(ctx, project.ID)
audience = domain.AddAudScopeToAudience(ctx, audience, scope)
if err != nil {
return nil, nil, err
}
return scope, audience, nil
}
func (o *OPStorage) createAuthRequestLoginClient(ctx context.Context, req *oidc.AuthRequest, hintUserID, loginClient string) (op.AuthRequest, error) {
scope, audience, err := o.createAuthRequestScopeAndAudience(ctx, req.ClientID, req.Scopes)
if err != nil {
return nil, err
}
authRequest := &command.AuthRequest{
LoginClient: loginClient,
ClientID: req.ClientID,
RedirectURI: req.RedirectURI,
State: req.State,
Nonce: req.Nonce,
Scope: scope,
Audience: audience,
NeedRefreshToken: slices.Contains(scope, oidc.ScopeOfflineAccess),
ResponseType: ResponseTypeToBusiness(req.ResponseType),
CodeChallenge: CodeChallengeToBusiness(req.CodeChallenge, req.CodeChallengeMethod),
Prompt: PromptToBusiness(req.Prompt),
UILocales: UILocalesToBusiness(req.UILocales),
MaxAge: MaxAgeToBusiness(req.MaxAge),
}
if req.LoginHint != "" {
authRequest.LoginHint = &req.LoginHint
}
if hintUserID != "" {
authRequest.HintUserID = &hintUserID
}
aar, err := o.command.AddAuthRequest(ctx, authRequest)
if err != nil {
return nil, err
}
return &AuthRequestV2{aar}, nil
}
func (o *OPStorage) createAuthRequest(ctx context.Context, req *oidc.AuthRequest, userID string) (_ op.AuthRequest, err error) {
userAgentID, ok := middleware.UserAgentIDFromCtx(ctx)
if !ok {
return nil, zerrors.ThrowPreconditionFailed(nil, "OIDC-sd436", "no user agent id")
}
scope, audience, err := o.createAuthRequestScopeAndAudience(ctx, req.ClientID, req.Scopes)
if err != nil {
return nil, err
}
req.Scopes = scope
authRequest := CreateAuthRequestToBusiness(ctx, req, userAgentID, userID, audience)
resp, err := o.repo.CreateAuthRequest(ctx, authRequest)
if err != nil {
return nil, err
}
return AuthRequestFromBusiness(resp)
}
func (o *OPStorage) audienceFromProjectID(ctx context.Context, projectID string) ([]string, error) {
projectIDQuery, err := query.NewAppProjectIDSearchQuery(projectID)
if err != nil {
return nil, err
}
appIDs, err := o.query.SearchClientIDs(ctx, &query.AppSearchQueries{Queries: []query.SearchQuery{projectIDQuery}}, true)
if err != nil {
return nil, err
}
return append(appIDs, projectID), nil
}
func (o *OPStorage) AuthRequestByID(ctx context.Context, id string) (_ op.AuthRequest, err error) {
ctx, span := tracing.NewSpan(ctx)
defer func() {
err = oidcError(err)
span.EndWithError(err)
}()
if strings.HasPrefix(id, command.IDPrefixV2) {
req, err := o.command.GetCurrentAuthRequest(ctx, id)
if err != nil {
return nil, err
}
return &AuthRequestV2{req}, nil
}
userAgentID, ok := middleware.UserAgentIDFromCtx(ctx)
if !ok {
return nil, zerrors.ThrowPreconditionFailed(nil, "OIDC-D3g21", "no user agent id")
}
resp, err := o.repo.AuthRequestByIDCheckLoggedIn(ctx, id, userAgentID)
if err != nil {
return nil, err
}
return AuthRequestFromBusiness(resp)
}
func (o *OPStorage) AuthRequestByCode(ctx context.Context, code string) (_ op.AuthRequest, err error) {
panic(o.panicErr("AuthRequestByCode"))
}
// decryptGrant decrypts a code or refresh_token
func (o *OPStorage) decryptGrant(grant string) (string, error) {
decodedGrant, err := base64.RawURLEncoding.DecodeString(grant)
if err != nil {
return "", err
}
return o.encAlg.DecryptString(decodedGrant, o.encAlg.EncryptionKeyID())
}
func (o *OPStorage) SaveAuthCode(ctx context.Context, id, code string) (err error) {
ctx, span := tracing.NewSpan(ctx)
defer func() {
err = oidcError(err)
span.EndWithError(err)
}()
if strings.HasPrefix(id, command.IDPrefixV2) {
return o.command.AddAuthRequestCode(ctx, id, code)
}
userAgentID, ok := middleware.UserAgentIDFromCtx(ctx)
if !ok {
return zerrors.ThrowPreconditionFailed(nil, "OIDC-Dgus2", "no user agent id")
}
return o.repo.SaveAuthCode(ctx, id, code, userAgentID)
}
func (o *OPStorage) DeleteAuthRequest(ctx context.Context, id string) (err error) {
panic(o.panicErr("DeleteAuthRequest"))
}
func (o *OPStorage) CreateAccessToken(ctx context.Context, req op.TokenRequest) (string, time.Time, error) {
panic(o.panicErr("CreateAccessToken"))
}
func (o *OPStorage) CreateAccessAndRefreshTokens(context.Context, op.TokenRequest, string) (string, string, time.Time, error) {
panic(o.panicErr("CreateAccessAndRefreshTokens"))
}
func (*OPStorage) panicErr(method string) error {
return fmt.Errorf("OPStorage.%s should not be called anymore. This is a bug. Please report https://github.com/zitadel/zitadel/issues", method)
}
func getInfoFromRequest(req op.TokenRequest) (agentID, clientID, userOrgID string, authTime time.Time, amr []string, preferredLanguage *language.Tag, reason domain.TokenReason, actor *domain.TokenActor) {
switch r := req.(type) {
case *AuthRequest:
return r.AgentID, r.ApplicationID, r.UserOrgID, r.AuthTime, r.GetAMR(), r.PreferredLanguage, domain.TokenReasonAuthRequest, nil
case *RefreshTokenRequest:
return r.UserAgentID, r.ClientID, "", r.AuthTime, r.AuthMethodsReferences, nil, domain.TokenReasonRefresh, r.Actor
case op.IDTokenRequest:
return "", r.GetClientID(), "", r.GetAuthTime(), r.GetAMR(), nil, domain.TokenReasonAuthRequest, nil
case *oidc.JWTTokenRequest:
return "", "", "", r.GetAuthTime(), nil, nil, domain.TokenReasonJWTProfile, nil
case *clientCredentialsRequest:
return "", "", "", time.Time{}, nil, nil, domain.TokenReasonClientCredentials, nil
default:
return "", "", "", time.Time{}, nil, nil, domain.TokenReasonAuthRequest, nil
}
}
func (o *OPStorage) TokenRequestByRefreshToken(ctx context.Context, refreshToken string) (_ op.RefreshTokenRequest, err error) {
panic("TokenRequestByRefreshToken should not be called anymore. This is a bug. Please report https://github.com/zitadel/zitadel/issues")
}
func (o *OPStorage) TerminateSession(ctx context.Context, userID, clientID string) (err error) {
ctx, span := tracing.NewSpan(ctx)
defer func() {
err = oidcError(err)
span.EndWithError(err)
}()
userAgentID, ok := middleware.UserAgentIDFromCtx(ctx)
if !ok {
logging.Error("no user agent id")
return zerrors.ThrowPreconditionFailed(nil, "OIDC-fso7F", "no user agent id")
}
userIDs, err := o.repo.UserSessionUserIDsByAgentID(ctx, userAgentID)
if err != nil {
logging.WithError(err).Error("error retrieving user sessions")
return err
}
if len(userIDs) == 0 {
return nil
}
data := authz.CtxData{
UserID: userID,
}
err = o.command.HumansSignOut(authz.SetCtxData(ctx, data), userAgentID, userIDs)
logging.OnError(err).Error("error signing out")
return err
}
func (o *OPStorage) TerminateSessionFromRequest(ctx context.Context, endSessionRequest *op.EndSessionRequest) (redirectURI string, err error) {
ctx, span := tracing.NewSpan(ctx)
defer func() {
err = oidcError(err)
span.EndWithError(err)
}()
// check for the login client header
headers, _ := http_utils.HeadersFromCtx(ctx)
// in case there is no id_token_hint, redirect to the UI and let it decide which session to terminate
if headers.Get(LoginClientHeader) != "" && endSessionRequest.IDTokenHintClaims == nil {
return o.defaultLogoutURLV2 + endSessionRequest.RedirectURI, nil
}
// If there is no login client header and no id_token_hint or the id_token_hint does not have a session ID,
// do a v1 Terminate session.
if endSessionRequest.IDTokenHintClaims == nil || endSessionRequest.IDTokenHintClaims.SessionID == "" {
return endSessionRequest.RedirectURI, o.TerminateSession(ctx, endSessionRequest.UserID, endSessionRequest.ClientID)
}
// terminate the v2 session of the id_token_hint
_, err = o.command.TerminateSessionWithoutTokenCheck(ctx, endSessionRequest.IDTokenHintClaims.SessionID)
if err != nil {
return "", err
}
return endSessionRequest.RedirectURI, nil
}
func (o *OPStorage) RevokeToken(ctx context.Context, token, userID, clientID string) (err *oidc.Error) {
ctx, span := tracing.NewSpan(ctx)
defer func() {
// check for nil, because `err` is not an error and EndWithError would panic
if err == nil {
span.End()
return
}
span.EndWithError(err)
}()
if strings.HasPrefix(token, command.IDPrefixV2) {
err := o.command.RevokeOIDCSessionToken(ctx, token, clientID)
if err == nil {
return nil
}
if zerrors.IsPreconditionFailed(err) {
return oidc.ErrInvalidClient().WithDescription("token was not issued for this client")
}
return oidc.ErrServerError().WithParent(err)
}
return o.revokeTokenV1(ctx, token, userID, clientID)
}
func (o *OPStorage) revokeTokenV1(ctx context.Context, token, userID, clientID string) *oidc.Error {
refreshToken, err := o.repo.RefreshTokenByID(ctx, token, userID)
if err == nil {
if refreshToken.ClientID != clientID {
return oidc.ErrInvalidClient().WithDescription("token was not issued for this client")
}
_, err = o.command.RevokeRefreshToken(ctx, refreshToken.UserID, refreshToken.ResourceOwner, refreshToken.ID)
if err == nil || zerrors.IsNotFound(err) {
return nil
}
return oidc.ErrServerError().WithParent(err)
}
accessToken, err := o.repo.TokenByIDs(ctx, userID, token)
if err != nil {
if zerrors.IsNotFound(err) {
return nil
}
return oidc.ErrServerError().WithParent(err)
}
if accessToken.ApplicationID != clientID {
return oidc.ErrInvalidClient().WithDescription("token was not issued for this client")
}
_, err = o.command.RevokeAccessToken(ctx, userID, accessToken.ResourceOwner, accessToken.ID)
if err == nil || zerrors.IsNotFound(err) {
return nil
}
return oidc.ErrServerError().WithParent(err)
}
func (o *OPStorage) GetRefreshTokenInfo(ctx context.Context, clientID string, token string) (userID string, tokenID string, err error) {
ctx, span := tracing.NewSpan(ctx)
defer func() {
err = oidcError(err)
span.EndWithError(err)
}()
plainToken, err := o.decryptGrant(token)
if err != nil {
return "", "", op.ErrInvalidRefreshToken
}
if strings.HasPrefix(plainToken, command.IDPrefixV2) {
oidcSession, err := o.command.OIDCSessionByRefreshToken(ctx, plainToken)
if err != nil {
return "", "", op.ErrInvalidRefreshToken
}
return oidcSession.UserID, oidcSession.OIDCRefreshTokenID(oidcSession.RefreshTokenID), nil
}
refreshToken, err := o.repo.RefreshTokenByToken(ctx, token)
if err != nil {
return "", "", op.ErrInvalidRefreshToken
}
if refreshToken.ClientID != clientID {
return "", "", oidc.ErrInvalidClient().WithDescription("token was not issued for this client")
}
return refreshToken.UserID, refreshToken.ID, nil
}
func (o *OPStorage) assertProjectRoleScopes(ctx context.Context, clientID string, scopes []string) ([]string, error) {
for _, scope := range scopes {
if strings.HasPrefix(scope, ScopeProjectRolePrefix) {
return scopes, nil
}
}
project, err := o.query.ProjectByOIDCClientID(ctx, clientID)
if err != nil {
return nil, zerrors.ThrowPreconditionFailed(nil, "OIDC-w4wIn", "Errors.Internal")
}
if !project.ProjectRoleAssertion {
return scopes, nil
}
projectIDQuery, err := query.NewProjectRoleProjectIDSearchQuery(project.ID)
if err != nil {
return nil, zerrors.ThrowInternal(err, "OIDC-Cyc78", "Errors.Internal")
}
roles, err := o.query.SearchProjectRoles(ctx, true, &query.ProjectRoleSearchQueries{Queries: []query.SearchQuery{projectIDQuery}})
if err != nil {
return nil, err
}
for _, role := range roles.ProjectRoles {
scopes = append(scopes, ScopeProjectRolePrefix+role.Key)
}
return scopes, nil
}
func (o *OPStorage) assertProjectRoleScopesByProject(ctx context.Context, project *query.Project, scopes []string) ([]string, error) {
for _, scope := range scopes {
if strings.HasPrefix(scope, ScopeProjectRolePrefix) {
return scopes, nil
}
}
if !project.ProjectRoleAssertion {
return scopes, nil
}
projectIDQuery, err := query.NewProjectRoleProjectIDSearchQuery(project.ID)
if err != nil {
return nil, zerrors.ThrowInternal(err, "OIDC-Cyc78", "Errors.Internal")
}
roles, err := o.query.SearchProjectRoles(ctx, true, &query.ProjectRoleSearchQueries{Queries: []query.SearchQuery{projectIDQuery}})
if err != nil {
return nil, err
}
for _, role := range roles.ProjectRoles {
scopes = append(scopes, ScopeProjectRolePrefix+role.Key)
}
return scopes, nil
}
func (o *OPStorage) assertClientScopesForPAT(ctx context.Context, token *model.TokenView, clientID, projectID string) error {
token.Audience = append(token.Audience, clientID)
projectIDQuery, err := query.NewProjectRoleProjectIDSearchQuery(projectID)
if err != nil {
return zerrors.ThrowInternal(err, "OIDC-Cyc78", "Errors.Internal")
}
roles, err := o.query.SearchProjectRoles(ctx, true, &query.ProjectRoleSearchQueries{Queries: []query.SearchQuery{projectIDQuery}})
if err != nil {
return err
}
for _, role := range roles.ProjectRoles {
token.Scopes = append(token.Scopes, ScopeProjectRolePrefix+role.Key)
}
return nil
}
func setContextUserSystem(ctx context.Context) context.Context {
data := authz.CtxData{
UserID: "SYSTEM",
}
return authz.SetCtxData(ctx, data)
}
func CreateErrorCallbackURL(authReq op.AuthRequest, reason, description, uri string, authorizer op.Authorizer) (string, error) {
e := struct {
Error string `schema:"error"`
Description string `schema:"error_description,omitempty"`
URI string `schema:"error_uri,omitempty"`
State string `schema:"state,omitempty"`
}{
Error: reason,
Description: description,
URI: uri,
State: authReq.GetState(),
}
callback, err := op.AuthResponseURL(authReq.GetRedirectURI(), authReq.GetResponseType(), authReq.GetResponseMode(), e, authorizer.Encoder())
if err != nil {
return "", err
}
return callback, nil
}
func CreateCodeCallbackURL(ctx context.Context, authReq op.AuthRequest, authorizer op.Authorizer) (string, error) {
code, err := op.CreateAuthRequestCode(ctx, authReq, authorizer.Storage(), authorizer.Crypto())
if err != nil {
return "", err
}
codeResponse := struct {
code string
state string
}{
code: code,
state: authReq.GetState(),
}
callback, err := op.AuthResponseURL(authReq.GetRedirectURI(), authReq.GetResponseType(), authReq.GetResponseMode(), &codeResponse, authorizer.Encoder())
if err != nil {
return "", err
}
return callback, err
}
func (s *Server) CreateTokenCallbackURL(ctx context.Context, req op.AuthRequest) (string, error) {
provider := s.Provider()
opClient, err := provider.Storage().GetClientByClientID(ctx, req.GetClientID())
if err != nil {
return "", err
}
client, ok := opClient.(*Client)
if !ok {
return "", zerrors.ThrowInternal(nil, "OIDC-waeN6", "Error.Internal")
}
session, state, err := s.command.CreateOIDCSessionFromAuthRequest(
setContextUserSystem(ctx),
req.GetID(),
implicitFlowComplianceChecker(),
slices.Contains(client.GrantTypes(), oidc.GrantTypeRefreshToken),
)
if err != nil {
return "", err
}
resp, err := s.accessTokenResponseFromSession(ctx, client, session, state, client.client.ProjectID, client.client.ProjectRoleAssertion)
if err != nil {
return "", err
}
callback, err := op.AuthResponseURL(req.GetRedirectURI(), req.GetResponseType(), req.GetResponseMode(), resp, provider.Encoder())
if err != nil {
return "", err
}
return callback, err
}
func implicitFlowComplianceChecker() command.AuthRequestComplianceChecker {
return func(_ context.Context, authReq *command.AuthRequestWriteModel) error {
if err := authReq.CheckAuthenticated(); err != nil {
return err
}
return nil
}
}
func (s *Server) authorizeCallbackHandler(w http.ResponseWriter, r *http.Request) {
authorizer := s.Provider()
authReq, err := func() (authReq op.AuthRequest, err error) {
ctx, span := tracing.NewSpan(r.Context())
r = r.WithContext(ctx)
defer func() { span.EndWithError(err) }()
id, err := op.ParseAuthorizeCallbackRequest(r)
if err != nil {
return nil, err
}
authReq, err = authorizer.Storage().AuthRequestByID(r.Context(), id)
if err != nil {
return nil, err
}
if !authReq.Done() {
return authReq, oidc.ErrInteractionRequired().WithDescription("Unfortunately, the user may be not logged in and/or additional interaction is required.")
}
return authReq, s.authResponse(authReq, authorizer, w, r)
}()
if err != nil {
op.AuthRequestError(w, r, authReq, err, authorizer)
}
}
func (s *Server) authResponse(authReq op.AuthRequest, authorizer op.Authorizer, w http.ResponseWriter, r *http.Request) (err error) {
ctx, span := tracing.NewSpan(r.Context())
r = r.WithContext(ctx)
defer func() { span.EndWithError(err) }()
client, err := authorizer.Storage().GetClientByClientID(ctx, authReq.GetClientID())
if err != nil {
op.AuthRequestError(w, r, authReq, err, authorizer)
return err
}
if authReq.GetResponseType() == oidc.ResponseTypeCode {
op.AuthResponseCode(w, r, authReq, authorizer)
return nil
}
return s.authResponseToken(authReq, authorizer, client, w, r)
}
func (s *Server) authResponseToken(authReq op.AuthRequest, authorizer op.Authorizer, opClient op.Client, w http.ResponseWriter, r *http.Request) (err error) {
ctx, span := tracing.NewSpan(r.Context())
r = r.WithContext(ctx)
defer func() { span.EndWithError(err) }()
client, ok := opClient.(*Client)
if !ok {
return zerrors.ThrowInternal(nil, "OIDC-waeN6", "Error.Internal")
}
userAgentID, _, userOrgID, authTime, authMethodsReferences, preferredLanguage, reason, actor := getInfoFromRequest(authReq)
scope := authReq.GetScopes()
session, err := s.command.CreateOIDCSession(ctx,
authReq.GetSubject(),
userOrgID,
client.client.ClientID,
scope,
authReq.GetAudience(),
AMRToAuthMethodTypes(authMethodsReferences),
authTime,
authReq.GetNonce(),
preferredLanguage,
&domain.UserAgent{
FingerprintID: &userAgentID,
},
reason,
actor,
slices.Contains(scope, oidc.ScopeOfflineAccess),
)
if err != nil {
op.AuthRequestError(w, r, authReq, err, authorizer)
return err
}
resp, err := s.accessTokenResponseFromSession(ctx, client, session, authReq.GetState(), client.client.ProjectID, client.client.ProjectRoleAssertion)
if err != nil {
op.AuthRequestError(w, r, authReq, err, authorizer)
return err
}
if authReq.GetResponseMode() == oidc.ResponseModeFormPost {
if err = op.AuthResponseFormPost(w, authReq.GetRedirectURI(), resp, authorizer.Encoder()); err != nil {
op.AuthRequestError(w, r, authReq, err, authorizer)
return err
}
return nil
}
callback, err := op.AuthResponseURL(authReq.GetRedirectURI(), authReq.GetResponseType(), authReq.GetResponseMode(), resp, authorizer.Encoder())
if err != nil {
op.AuthRequestError(w, r, authReq, err, authorizer)
return err
}
http.Redirect(w, r, callback, http.StatusFound)
return nil
}