gecko-dev/services/sync/modules/browserid_identity.js

792 строки
29 KiB
JavaScript

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
"use strict";
this.EXPORTED_SYMBOLS = ["BrowserIDManager"];
const {classes: Cc, interfaces: Ci, utils: Cu, results: Cr} = Components;
Cu.import("resource://gre/modules/Log.jsm");
Cu.import("resource://services-common/async.js");
Cu.import("resource://services-common/utils.js");
Cu.import("resource://services-common/tokenserverclient.js");
Cu.import("resource://services-crypto/utils.js");
Cu.import("resource://services-sync/identity.js");
Cu.import("resource://services-sync/util.js");
Cu.import("resource://services-common/tokenserverclient.js");
Cu.import("resource://gre/modules/Services.jsm");
Cu.import("resource://services-sync/constants.js");
Cu.import("resource://gre/modules/Promise.jsm");
Cu.import("resource://services-sync/stages/cluster.js");
Cu.import("resource://gre/modules/FxAccounts.jsm");
// Lazy imports to prevent unnecessary load on startup.
XPCOMUtils.defineLazyModuleGetter(this, "Weave",
"resource://services-sync/main.js");
XPCOMUtils.defineLazyModuleGetter(this, "BulkKeyBundle",
"resource://services-sync/keys.js");
XPCOMUtils.defineLazyModuleGetter(this, "fxAccounts",
"resource://gre/modules/FxAccounts.jsm");
XPCOMUtils.defineLazyGetter(this, 'log', function() {
let log = Log.repository.getLogger("Sync.BrowserIDManager");
log.level = Log.Level[Svc.Prefs.get("log.logger.identity")] || Log.Level.Error;
return log;
});
// FxAccountsCommon.js doesn't use a "namespace", so create one here.
let fxAccountsCommon = {};
Cu.import("resource://gre/modules/FxAccountsCommon.js", fxAccountsCommon);
const OBSERVER_TOPICS = [
fxAccountsCommon.ONLOGIN_NOTIFICATION,
fxAccountsCommon.ONLOGOUT_NOTIFICATION,
];
const PREF_SYNC_SHOW_CUSTOMIZATION = "services.sync-setup.ui.showCustomizationDialog";
function deriveKeyBundle(kB) {
let out = CryptoUtils.hkdf(kB, undefined,
"identity.mozilla.com/picl/v1/oldsync", 2*32);
let bundle = new BulkKeyBundle();
// [encryptionKey, hmacKey]
bundle.keyPair = [out.slice(0, 32), out.slice(32, 64)];
return bundle;
}
/*
General authentication error for abstracting authentication
errors from multiple sources (e.g., from FxAccounts, TokenServer).
details is additional details about the error - it might be a string, or
some other error object (which should do the right thing when toString() is
called on it)
*/
function AuthenticationError(details) {
this.details = details;
}
AuthenticationError.prototype = {
toString: function() {
return "AuthenticationError(" + this.details + ")";
}
}
this.BrowserIDManager = function BrowserIDManager() {
// NOTE: _fxaService and _tokenServerClient are replaced with mocks by
// the test suite.
this._fxaService = fxAccounts;
this._tokenServerClient = new TokenServerClient();
this._tokenServerClient.observerPrefix = "weave:service";
// will be a promise that resolves when we are ready to authenticate
this.whenReadyToAuthenticate = null;
this._log = log;
};
this.BrowserIDManager.prototype = {
__proto__: IdentityManager.prototype,
_fxaService: null,
_tokenServerClient: null,
// https://docs.services.mozilla.com/token/apis.html
_token: null,
_signedInUser: null, // the signedinuser we got from FxAccounts.
// null if no error, otherwise a LOGIN_FAILED_* value that indicates why
// we failed to authenticate (but note it might not be an actual
// authentication problem, just a transient network error or similar)
_authFailureReason: null,
// it takes some time to fetch a sync key bundle, so until this flag is set,
// we don't consider the lack of a keybundle as a failure state.
_shouldHaveSyncKeyBundle: false,
get readyToAuthenticate() {
// We are finished initializing when we *should* have a sync key bundle,
// although we might not actually have one due to auth failures etc.
return this._shouldHaveSyncKeyBundle;
},
get needsCustomization() {
try {
return Services.prefs.getBoolPref(PREF_SYNC_SHOW_CUSTOMIZATION);
} catch (e) {
return false;
}
},
initialize: function() {
for (let topic of OBSERVER_TOPICS) {
Services.obs.addObserver(this, topic, false);
}
return this.initializeWithCurrentIdentity();
},
/**
* Ensure the user is logged in. Returns a promise that resolves when
* the user is logged in, or is rejected if the login attempt has failed.
*/
ensureLoggedIn: function() {
if (!this._shouldHaveSyncKeyBundle) {
// We are already in the process of logging in.
return this.whenReadyToAuthenticate.promise;
}
// If we are already happy then there is nothing more to do.
if (this._syncKeyBundle) {
return Promise.resolve();
}
// Similarly, if we have a previous failure that implies an explicit
// re-entering of credentials by the user is necessary we don't take any
// further action - an observer will fire when the user does that.
if (Weave.Status.login == LOGIN_FAILED_LOGIN_REJECTED) {
return Promise.reject(new Error("User needs to re-authenticate"));
}
// So - we've a previous auth problem and aren't currently attempting to
// log in - so fire that off.
this.initializeWithCurrentIdentity();
return this.whenReadyToAuthenticate.promise;
},
finalize: function() {
// After this is called, we can expect Service.identity != this.
for (let topic of OBSERVER_TOPICS) {
Services.obs.removeObserver(this, topic);
}
this.resetCredentials();
this._signedInUser = null;
return Promise.resolve();
},
offerSyncOptions: function () {
// If the user chose to "Customize sync options" when signing
// up with Firefox Accounts, ask them to choose what to sync.
const url = "chrome://browser/content/sync/customize.xul";
const features = "centerscreen,chrome,modal,dialog,resizable=no";
let win = Services.wm.getMostRecentWindow("navigator:browser");
let data = {accepted: false};
win.openDialog(url, "_blank", features, data);
return data;
},
initializeWithCurrentIdentity: function(isInitialSync=false) {
// While this function returns a promise that resolves once we've started
// the auth process, that process is complete when
// this.whenReadyToAuthenticate.promise resolves.
this._log.trace("initializeWithCurrentIdentity");
// Reset the world before we do anything async.
this.whenReadyToAuthenticate = Promise.defer();
this.whenReadyToAuthenticate.promise.then(null, (err) => {
this._log.error("Could not authenticate", err);
});
// initializeWithCurrentIdentity() can be called after the
// identity module was first initialized, e.g., after the
// user completes a force authentication, so we should make
// sure all credentials are reset before proceeding.
this.resetCredentials();
this._authFailureReason = null;
return this._fxaService.getSignedInUser().then(accountData => {
if (!accountData) {
this._log.info("initializeWithCurrentIdentity has no user logged in");
this.account = null;
// and we are as ready as we can ever be for auth.
this._shouldHaveSyncKeyBundle = true;
this.whenReadyToAuthenticate.reject("no user is logged in");
return;
}
this.account = accountData.email;
this._updateSignedInUser(accountData);
// The user must be verified before we can do anything at all; we kick
// this and the rest of initialization off in the background (ie, we
// don't return the promise)
this._log.info("Waiting for user to be verified.");
this._fxaService.whenVerified(accountData).then(accountData => {
this._updateSignedInUser(accountData);
this._log.info("Starting fetch for key bundle.");
if (this.needsCustomization) {
let data = this.offerSyncOptions();
if (data.accepted) {
Services.prefs.clearUserPref(PREF_SYNC_SHOW_CUSTOMIZATION);
// Mark any non-selected engines as declined.
Weave.Service.engineManager.declineDisabled();
} else {
// Log out if the user canceled the dialog.
return this._fxaService.signOut();
}
}
}).then(() => {
return this._fetchTokenForUser();
}).then(token => {
this._token = token;
this._shouldHaveSyncKeyBundle = true; // and we should actually have one...
this.whenReadyToAuthenticate.resolve();
this._log.info("Background fetch for key bundle done");
Weave.Status.login = LOGIN_SUCCEEDED;
if (isInitialSync) {
this._log.info("Doing initial sync actions");
Svc.Prefs.set("firstSync", "resetClient");
Services.obs.notifyObservers(null, "weave:service:setup-complete", null);
Weave.Utils.nextTick(Weave.Service.sync, Weave.Service);
}
}).then(null, err => {
this._shouldHaveSyncKeyBundle = true; // but we probably don't have one...
this.whenReadyToAuthenticate.reject(err);
// report what failed...
this._log.error("Background fetch for key bundle failed", err);
});
// and we are done - the fetch continues on in the background...
}).then(null, err => {
this._log.error("Processing logged in account", err);
});
},
_updateSignedInUser: function(userData) {
// This object should only ever be used for a single user. It is an
// error to update the data if the user changes (but updates are still
// necessary, as each call may add more attributes to the user).
// We start with no user, so an initial update is always ok.
if (this._signedInUser && this._signedInUser.email != userData.email) {
throw new Error("Attempting to update to a different user.")
}
this._signedInUser = userData;
},
logout: function() {
// This will be called when sync fails (or when the account is being
// unlinked etc). It may have failed because we got a 401 from a sync
// server, so we nuke the token. Next time sync runs and wants an
// authentication header, we will notice the lack of the token and fetch a
// new one.
this._token = null;
},
observe: function (subject, topic, data) {
this._log.debug("observed " + topic);
switch (topic) {
case fxAccountsCommon.ONLOGIN_NOTIFICATION:
// This should only happen if we've been initialized without a current
// user - otherwise we'd have seen the LOGOUT notification and been
// thrown away.
// The exception is when we've initialized with a user that needs to
// reauth with the server - in that case we will also get here, but
// should have the same identity.
// initializeWithCurrentIdentity will throw and log if these contraints
// aren't met, so just go ahead and do the init.
this.initializeWithCurrentIdentity(true);
break;
case fxAccountsCommon.ONLOGOUT_NOTIFICATION:
Weave.Service.startOver();
// startOver will cause this instance to be thrown away, so there's
// nothing else to do.
break;
}
},
/**
* Compute the sha256 of the message bytes. Return bytes.
*/
_sha256: function(message) {
let hasher = Cc["@mozilla.org/security/hash;1"]
.createInstance(Ci.nsICryptoHash);
hasher.init(hasher.SHA256);
return CryptoUtils.digestBytes(message, hasher);
},
/**
* Compute the X-Client-State header given the byte string kB.
*
* Return string: hex(first16Bytes(sha256(kBbytes)))
*/
_computeXClientState: function(kBbytes) {
return CommonUtils.bytesAsHex(this._sha256(kBbytes).slice(0, 16), false);
},
/**
* Provide override point for testing token expiration.
*/
_now: function() {
return this._fxaService.now()
},
get _localtimeOffsetMsec() {
return this._fxaService.localtimeOffsetMsec;
},
usernameFromAccount: function(val) {
// we don't differentiate between "username" and "account"
return val;
},
/**
* Obtains the HTTP Basic auth password.
*
* Returns a string if set or null if it is not set.
*/
get basicPassword() {
this._log.error("basicPassword getter should be not used in BrowserIDManager");
return null;
},
/**
* Set the HTTP basic password to use.
*
* Changes will not persist unless persistSyncCredentials() is called.
*/
set basicPassword(value) {
throw "basicPassword setter should be not used in BrowserIDManager";
},
/**
* Obtain the Sync Key.
*
* This returns a 26 character "friendly" Base32 encoded string on success or
* null if no Sync Key could be found.
*
* If the Sync Key hasn't been set in this session, this will look in the
* password manager for the sync key.
*/
get syncKey() {
if (this.syncKeyBundle) {
// TODO: This is probably fine because the code shouldn't be
// using the sync key directly (it should use the sync key
// bundle), but I don't like it. We should probably refactor
// code that is inspecting this to not do validation on this
// field directly and instead call a isSyncKeyValid() function
// that we can override.
return "99999999999999999999999999";
}
else {
return null;
}
},
set syncKey(value) {
throw "syncKey setter should be not used in BrowserIDManager";
},
get syncKeyBundle() {
return this._syncKeyBundle;
},
/**
* Resets/Drops all credentials we hold for the current user.
*/
resetCredentials: function() {
this.resetSyncKey();
this._token = null;
},
/**
* Resets/Drops the sync key we hold for the current user.
*/
resetSyncKey: function() {
this._syncKey = null;
this._syncKeyBundle = null;
this._syncKeyUpdated = true;
this._shouldHaveSyncKeyBundle = false;
},
/**
* Pre-fetches any information that might help with migration away from this
* identity. Called after every sync and is really just an optimization that
* allows us to avoid a network request for when we actually need the
* migration info.
*/
prefetchMigrationSentinel: function(service) {
// nothing to do here until we decide to migrate away from FxA.
},
/**
* Return credentials hosts for this identity only.
*/
_getSyncCredentialsHosts: function() {
return Utils.getSyncCredentialsHostsFxA();
},
/**
* The current state of the auth credentials.
*
* This essentially validates that enough credentials are available to use
* Sync, although it effectively ignores the state of the master-password -
* if that's locked and that's the only problem we can see, say everything
* is OK - unlockAndVerifyAuthState will be used to perform the unlock
* and re-verification if necessary.
*/
get currentAuthState() {
if (this._authFailureReason) {
this._log.info("currentAuthState returning " + this._authFailureReason +
" due to previous failure");
return this._authFailureReason;
}
// TODO: need to revisit this. Currently this isn't ready to go until
// both the username and syncKeyBundle are both configured and having no
// username seems to make things fail fast so that's good.
if (!this.username) {
return LOGIN_FAILED_NO_USERNAME;
}
// No need to check this.syncKey as our getter for that attribute
// uses this.syncKeyBundle
// If bundle creation started, but failed due to any reason other than
// the MP being locked...
if (this._shouldHaveSyncKeyBundle && !this.syncKeyBundle && !Utils.mpLocked()) {
// Return a state that says a re-auth is necessary so we can get keys.
return LOGIN_FAILED_LOGIN_REJECTED;
}
return STATUS_OK;
},
// Do we currently have keys, or do we have enough that we should be able
// to successfully fetch them?
_canFetchKeys: function() {
let userData = this._signedInUser;
// a keyFetchToken means we can almost certainly grab them.
// kA and kB means we already have them.
return userData && (userData.keyFetchToken || (userData.kA && userData.kB));
},
/**
* Verify the current auth state, unlocking the master-password if necessary.
*
* Returns a promise that resolves with the current auth state after
* attempting to unlock.
*/
unlockAndVerifyAuthState: function() {
if (this._canFetchKeys()) {
return Promise.resolve(STATUS_OK);
}
// so no keys - ensure MP unlocked.
if (!Utils.ensureMPUnlocked()) {
// user declined to unlock, so we don't know if they are stored there.
return Promise.resolve(MASTER_PASSWORD_LOCKED);
}
// now we are unlocked we must re-fetch the user data as we may now have
// the details that were previously locked away.
return this._fxaService.getSignedInUser().then(
accountData => {
this._updateSignedInUser(accountData);
// If we still can't get keys it probably means the user authenticated
// without unlocking the MP or cleared the saved logins, so we've now
// lost them - the user will need to reauth before continuing.
return this._canFetchKeys() ? STATUS_OK : LOGIN_FAILED_LOGIN_REJECTED;
}
);
},
/**
* Do we have a non-null, not yet expired token for the user currently
* signed in?
*/
hasValidToken: function() {
// If pref is set to ignore cached authentication credentials for debugging,
// then return false to force the fetching of a new token.
let ignoreCachedAuthCredentials = false;
try {
ignoreCachedAuthCredentials = Svc.Prefs.get("debug.ignoreCachedAuthCredentials");
} catch(e) {
// Pref doesn't exist
}
if (ignoreCachedAuthCredentials) {
return false;
}
if (!this._token) {
return false;
}
if (this._token.expiration < this._now()) {
return false;
}
return true;
},
// Refresh the sync token for our user. Returns a promise that resolves
// with a token (which may be null in one sad edge-case), or rejects with an
// error.
_fetchTokenForUser: function() {
let tokenServerURI = Svc.Prefs.get("tokenServerURI");
if (tokenServerURI.endsWith("/")) { // trailing slashes cause problems...
tokenServerURI = tokenServerURI.slice(0, -1);
}
let log = this._log;
let client = this._tokenServerClient;
let fxa = this._fxaService;
let userData = this._signedInUser;
// We need kA and kB for things to work. If we don't have them, just
// return null for the token - sync calling unlockAndVerifyAuthState()
// before actually syncing will setup the error states if necessary.
if (!this._canFetchKeys()) {
return Promise.resolve(null);
}
let maybeFetchKeys = () => {
// This is called at login time and every time we need a new token - in
// the latter case we already have kA and kB, so optimise that case.
if (userData.kA && userData.kB) {
return;
}
log.info("Fetching new keys");
return this._fxaService.getKeys().then(
newUserData => {
userData = newUserData;
this._updateSignedInUser(userData); // throws if the user changed.
}
);
}
let getToken = (tokenServerURI, assertion) => {
log.debug("Getting a token");
let deferred = Promise.defer();
let cb = function (err, token) {
if (err) {
return deferred.reject(err);
}
log.debug("Successfully got a sync token");
return deferred.resolve(token);
};
let kBbytes = CommonUtils.hexToBytes(userData.kB);
let headers = {"X-Client-State": this._computeXClientState(kBbytes)};
client.getTokenFromBrowserIDAssertion(tokenServerURI, assertion, cb, headers);
return deferred.promise;
}
let getAssertion = () => {
log.info("Getting an assertion from", tokenServerURI);
let audience = Services.io.newURI(tokenServerURI, null, null).prePath;
return fxa.getAssertion(audience);
};
// wait until the account email is verified and we know that
// getAssertion() will return a real assertion (not null).
return fxa.whenVerified(this._signedInUser)
.then(() => maybeFetchKeys())
.then(() => getAssertion())
.then(assertion => getToken(tokenServerURI, assertion))
.then(token => {
// TODO: Make it be only 80% of the duration, so refresh the token
// before it actually expires. This is to avoid sync storage errors
// otherwise, we get a nasty notification bar briefly. Bug 966568.
token.expiration = this._now() + (token.duration * 1000) * 0.80;
if (!this._syncKeyBundle) {
// We are given kA/kB as hex.
this._syncKeyBundle = deriveKeyBundle(Utils.hexToBytes(userData.kB));
}
return token;
})
.then(null, err => {
// TODO: unify these errors - we need to handle errors thrown by
// both tokenserverclient and hawkclient.
// A tokenserver error thrown based on a bad response.
if (err.response && err.response.status === 401) {
err = new AuthenticationError(err);
// A hawkclient error.
} else if (err.code && err.code === 401) {
err = new AuthenticationError(err);
}
// TODO: write tests to make sure that different auth error cases are handled here
// properly: auth error getting assertion, auth error getting token (invalid generation
// and client-state error)
if (err instanceof AuthenticationError) {
this._log.error("Authentication error in _fetchTokenForUser", err);
// set it to the "fatal" LOGIN_FAILED_LOGIN_REJECTED reason.
this._authFailureReason = LOGIN_FAILED_LOGIN_REJECTED;
} else {
this._log.error("Non-authentication error in _fetchTokenForUser", err);
// for now assume it is just a transient network related problem
// (although sadly, it might also be a regular unhandled exception)
this._authFailureReason = LOGIN_FAILED_NETWORK_ERROR;
}
// this._authFailureReason being set to be non-null in the above if clause
// ensures we are in the correct currentAuthState, and
// this._shouldHaveSyncKeyBundle being true ensures everything that cares knows
// that there is no authentication dance still under way.
this._shouldHaveSyncKeyBundle = true;
Weave.Status.login = this._authFailureReason;
Services.obs.notifyObservers(null, "weave:ui:login:error", null);
throw err;
});
},
// Returns a promise that is resolved when we have a valid token for the
// current user stored in this._token. When resolved, this._token is valid.
_ensureValidToken: function() {
if (this.hasValidToken()) {
this._log.debug("_ensureValidToken already has one");
return Promise.resolve();
}
// reset this._token as a safety net to reduce the possibility of us
// repeatedly attempting to use an invalid token if _fetchTokenForUser throws.
this._token = null;
return this._fetchTokenForUser().then(
token => {
this._token = token;
}
);
},
getResourceAuthenticator: function () {
return this._getAuthenticationHeader.bind(this);
},
/**
* Obtain a function to be used for adding auth to RESTRequest instances.
*/
getRESTRequestAuthenticator: function() {
return this._addAuthenticationHeader.bind(this);
},
/**
* @return a Hawk HTTP Authorization Header, lightly wrapped, for the .uri
* of a RESTRequest or AsyncResponse object.
*/
_getAuthenticationHeader: function(httpObject, method) {
let cb = Async.makeSpinningCallback();
this._ensureValidToken().then(cb, cb);
try {
cb.wait();
} catch (ex) {
this._log.error("Failed to fetch a token for authentication", ex);
return null;
}
if (!this._token) {
return null;
}
let credentials = {algorithm: "sha256",
id: this._token.id,
key: this._token.key,
};
method = method || httpObject.method;
// Get the local clock offset from the Firefox Accounts server. This should
// be close to the offset from the storage server.
let options = {
now: this._now(),
localtimeOffsetMsec: this._localtimeOffsetMsec,
credentials: credentials,
};
let headerValue = CryptoUtils.computeHAWK(httpObject.uri, method, options);
return {headers: {authorization: headerValue.field}};
},
_addAuthenticationHeader: function(request, method) {
let header = this._getAuthenticationHeader(request, method);
if (!header) {
return null;
}
request.setHeader("authorization", header.headers.authorization);
return request;
},
createClusterManager: function(service) {
return new BrowserIDClusterManager(service);
}
};
/* An implementation of the ClusterManager for this identity
*/
function BrowserIDClusterManager(service) {
ClusterManager.call(this, service);
}
BrowserIDClusterManager.prototype = {
__proto__: ClusterManager.prototype,
_findCluster: function() {
let endPointFromIdentityToken = function() {
// The only reason (in theory ;) that we can end up with a null token
// is when this.identity._canFetchKeys() returned false. In turn, this
// should only happen if the master-password is locked or the credentials
// storage is screwed, and in those cases we shouldn't have started
// syncing so shouldn't get here anyway.
// But better safe than sorry! To keep things clearer, throw an explicit
// exception - the message will appear in the logs and the error will be
// treated as transient.
if (!this.identity._token) {
throw new Error("Can't get a cluster URL as we can't fetch keys.");
}
let endpoint = this.identity._token.endpoint;
// For Sync 1.5 storage endpoints, we use the base endpoint verbatim.
// However, it should end in "/" because we will extend it with
// well known path components. So we add a "/" if it's missing.
if (!endpoint.endsWith("/")) {
endpoint += "/";
}
log.debug("_findCluster returning " + endpoint);
return endpoint;
}.bind(this);
// Spinningly ensure we are ready to authenticate and have a valid token.
let promiseClusterURL = function() {
return this.identity.whenReadyToAuthenticate.promise.then(
() => {
// We need to handle node reassignment here. If we are being asked
// for a clusterURL while the service already has a clusterURL, then
// it's likely a 401 was received using the existing token - in which
// case we just discard the existing token and fetch a new one.
if (this.service.clusterURL) {
log.debug("_findCluster found existing clusterURL, so discarding the current token");
this.identity._token = null;
}
return this.identity._ensureValidToken();
}
).then(endPointFromIdentityToken
);
}.bind(this);
let cb = Async.makeSpinningCallback();
promiseClusterURL().then(function (clusterURL) {
cb(null, clusterURL);
}).then(
null, err => {
log.info("Failed to fetch the cluster URL", err);
// service.js's verifyLogin() method will attempt to fetch a cluster
// URL when it sees a 401. If it gets null, it treats it as a "real"
// auth error and sets Status.login to LOGIN_FAILED_LOGIN_REJECTED, which
// in turn causes a notification bar to appear informing the user they
// need to re-authenticate.
// On the other hand, if fetching the cluster URL fails with an exception,
// verifyLogin() assumes it is a transient error, and thus doesn't show
// the notification bar under the assumption the issue will resolve
// itself.
// Thus:
// * On a real 401, we must return null.
// * On any other problem we must let an exception bubble up.
if (err instanceof AuthenticationError) {
// callback with no error and a null result - cb.wait() returns null.
cb(null, null);
} else {
// callback with an error - cb.wait() completes by raising an exception.
cb(err);
}
});
return cb.wait();
},
getUserBaseURL: function() {
// Legacy Sync and FxA Sync construct the userBaseURL differently. Legacy
// Sync appends path components onto an empty path, and in FxA Sync the
// token server constructs this for us in an opaque manner. Since the
// cluster manager already sets the clusterURL on Service and also has
// access to the current identity, we added this functionality here.
return this.service.clusterURL;
}
}