shibsp/handler/impl/SAML2Logout.cpp

   1 /*
   2  *  Copyright 2001-2007 Internet2
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 /**
  18  * SAML2Logout.cpp
  19  *
  20  * Handles SAML 2.0 single logout protocol messages.
  21  */
  22
  23 #include "internal.h"
  24 #include "exceptions.h"
  25 #include "Application.h"
  26 #include "ServiceProvider.h"
  27 #include "handler/AbstractHandler.h"
  28 #include "handler/LogoutHandler.h"
  29 #include "util/SPConstants.h"
  30
  31 #ifndef SHIBSP_LITE
  32 # include "SessionCache.h"
  33 # include "security/SecurityPolicy.h"
  34 # include "util/TemplateParameters.h"
  35 # include <fstream>
  36 # include <saml/SAMLConfig.h>
  37 # include <saml/saml2/core/Protocols.h>
  38 # include <saml/saml2/metadata/EndpointManager.h>
  39 # include <saml/saml2/metadata/MetadataCredentialCriteria.h>
  40 # include <xmltooling/util/URLEncoder.h>
  41 using namespace opensaml::saml2;
  42 using namespace opensaml::saml2p;
  43 using namespace opensaml::saml2md;
  44 using namespace opensaml;
  45 #endif
  46
  47 using namespace shibsp;
  48 using namespace xmltooling;
  49 using namespace std;
  50
  51 namespace shibsp {
  52
  53 #if defined (_MSC_VER)
  54     #pragma warning( push )
  55     #pragma warning( disable : 4250 )
  56 #endif
  57
  58     class SHIBSP_DLLLOCAL SAML2Logout : public AbstractHandler, public LogoutHandler
  59     {
  60     public:
  61         SAML2Logout(const DOMElement* e, const char* appId);
  62         virtual ~SAML2Logout() {
  63 #ifndef SHIBSP_LITE
  64             if (SPConfig::getConfig().isEnabled(SPConfig::OutOfProcess)) {
  65                 delete m_decoder;
  66                 XMLString::release(&m_outgoing);
  67                 for_each(m_encoders.begin(), m_encoders.end(), cleanup_pair<const XMLCh*,MessageEncoder>());
  68             }
  69 #endif
  70         }
  71
  72         void receive(DDF& in, ostream& out);
  73         pair<bool,long> run(SPRequest& request, bool isHandler=true) const;
  74
  75     private:
  76         pair<bool,long> doRequest(
  77             const Application& application, const char* session_id, const HTTPRequest& httpRequest, HTTPResponse& httpResponse
  78             ) const;
  79
  80 #ifndef SHIBSP_LITE
  81         bool stronglyMatches(const XMLCh* idp, const XMLCh* sp, const saml2::NameID& n1, const saml2::NameID& n2) const;
  82
  83         pair<bool,long> sendResponse(
  84             const XMLCh* requestID,
  85             const XMLCh* code,
  86             const XMLCh* subcode,
  87             const char* msg,
  88             const char* relayState,
  89             const RoleDescriptor* role,
  90             const Application& application,
  91             HTTPResponse& httpResponse,
  92             bool front
  93             ) const;
  94
  95         QName m_role;
  96         MessageDecoder* m_decoder;
  97         XMLCh* m_outgoing;
  98         vector<const XMLCh*> m_bindings;
  99         map<const XMLCh*,MessageEncoder*> m_encoders;
 100 #endif
 101     };
 102
 103 #if defined (_MSC_VER)
 104     #pragma warning( pop )
 105 #endif
 106
 107     Handler* SHIBSP_DLLLOCAL SAML2LogoutFactory(const pair<const DOMElement*,const char*>& p)
 108     {
 109         return new SAML2Logout(p.first, p.second);
 110     }
 111 };
 112
 113 SAML2Logout::SAML2Logout(const DOMElement* e, const char* appId)
 114     : AbstractHandler(e, Category::getInstance(SHIBSP_LOGCAT".Logout.SAML2"))
 115 #ifndef SHIBSP_LITE
 116         ,m_role(samlconstants::SAML20MD_NS, IDPSSODescriptor::LOCAL_NAME), m_decoder(NULL), m_outgoing(NULL)
 117 #endif
 118 {
 119 #ifndef SHIBSP_LITE
 120     m_initiator = false;
 121     m_preserve.push_back("ID");
 122     m_preserve.push_back("entityID");
 123     m_preserve.push_back("RelayState");
 124
 125     if (SPConfig::getConfig().isEnabled(SPConfig::OutOfProcess)) {
 126         SAMLConfig& conf = SAMLConfig::getConfig();
 127
 128         // Handle incoming binding.
 129         m_decoder = conf.MessageDecoderManager.newPlugin(getString("Binding").second,make_pair(e,shibspconstants::SHIB2SPCONFIG_NS));
 130         m_decoder->setArtifactResolver(SPConfig::getConfig().getArtifactResolver());
 131
 132         if (m_decoder->isUserAgentPresent()) {
 133             // Handle front-channel binding setup.
 134             pair<bool,const XMLCh*> outgoing = getXMLString("outgoingBindings", m_configNS.get());
 135             if (outgoing.first) {
 136                 m_outgoing = XMLString::replicate(outgoing.second);
 137                 XMLString::trim(m_outgoing);
 138             }
 139             else {
 140                 // No override, so we'll install a default binding precedence.
 141                 string prec = string(samlconstants::SAML20_BINDING_HTTP_REDIRECT) + ' ' + samlconstants::SAML20_BINDING_HTTP_POST + ' ' +
 142                     samlconstants::SAML20_BINDING_HTTP_POST_SIMPLESIGN + ' ' + samlconstants::SAML20_BINDING_HTTP_ARTIFACT;
 143                 m_outgoing = XMLString::transcode(prec.c_str());
 144             }
 145
 146             int pos;
 147             XMLCh* start = m_outgoing;
 148             while (start && *start) {
 149                 pos = XMLString::indexOf(start,chSpace);
 150                 if (pos != -1)
 151                     *(start + pos)=chNull;
 152                 m_bindings.push_back(start);
 153                 try {
 154                     auto_ptr_char b(start);
 155                     MessageEncoder * encoder = conf.MessageEncoderManager.newPlugin(b.get(),make_pair(e,shibspconstants::SHIB2SPCONFIG_NS));
 156                     m_encoders[start] = encoder;
 157                     m_log.debug("supporting outgoing front-channel binding (%s)", b.get());
 158                 }
 159                 catch (exception& ex) {
 160                     m_log.error("error building MessageEncoder: %s", ex.what());
 161                 }
 162                 if (pos != -1)
 163                     start = start + pos + 1;
 164                 else
 165                     break;
 166             }
 167         }
 168         else {
 169             MessageEncoder* encoder = conf.MessageEncoderManager.newPlugin(
 170                 getString("Binding").second,make_pair(e,shibspconstants::SHIB2SPCONFIG_NS)
 171                 );
 172             m_encoders.insert(pair<const XMLCh*,MessageEncoder*>(NULL, encoder));
 173         }
 174     }
 175 #endif
 176
 177     string address(appId);
 178     address += getString("Location").second;
 179     setAddress(address.c_str());
 180 }
 181
 182 pair<bool,long> SAML2Logout::run(SPRequest& request, bool isHandler) const
 183 {
 184     // Defer to base class for front-channel loop first.
 185     // This won't initiate the loop, only continue/end it.
 186     pair<bool,long> ret = LogoutHandler::run(request, isHandler);
 187     if (ret.first)
 188         return ret;
 189
 190     // Get the session_id in case this is a front-channel LogoutRequest.
 191     pair<string,const char*> shib_cookie = request.getApplication().getCookieNameProps("_shibsession_");
 192     const char* session_id = request.getCookie(shib_cookie.first.c_str());
 193
 194     SPConfig& conf = SPConfig::getConfig();
 195     if (conf.isEnabled(SPConfig::OutOfProcess)) {
 196         // When out of process, we run natively and directly process the message.
 197         return doRequest(request.getApplication(), session_id, request, request);
 198     }
 199     else {
 200         // When not out of process, we remote all the message processing.
 201         DDF out,in = wrap(request, NULL, true);
 202         DDFJanitor jin(in), jout(out);
 203         if (session_id)
 204             in.addmember("session_id").string(session_id);
 205         out=request.getServiceProvider().getListenerService()->send(in);
 206         return unwrap(request, out);
 207     }
 208 }
 209
 210 void SAML2Logout::receive(DDF& in, ostream& out)
 211 {
 212     // Find application.
 213     const char* aid=in["application_id"].string();
 214     const Application* app=aid ? SPConfig::getConfig().getServiceProvider()->getApplication(aid) : NULL;
 215     if (!app) {
 216         // Something's horribly wrong.
 217         m_log.error("couldn't find application (%s) for logout", aid ? aid : "(missing)");
 218         throw ConfigurationException("Unable to locate application for logout, deleted?");
 219     }
 220
 221     // Unpack the request.
 222     DDF ret(NULL);
 223     DDFJanitor jout(ret);
 224     auto_ptr<HTTPRequest> req(getRequest(in));
 225     auto_ptr<HTTPResponse> resp(getResponse(ret));
 226
 227     // Since we're remoted, the result should either be a throw, which we pass on,
 228     // a false/0 return, which we just return as an empty structure, or a response/redirect,
 229     // which we capture in the facade and send back.
 230     doRequest(*app, in["session_id"].string(), *req.get(), *resp.get());
 231     out << ret;
 232 }
 233
 234 pair<bool,long> SAML2Logout::doRequest(
 235     const Application& application, const char* session_id, const HTTPRequest& request, HTTPResponse& response
 236     ) const
 237 {
 238 #ifndef SHIBSP_LITE
 239     SessionCache* cache = application.getServiceProvider().getSessionCache();
 240     if (!strcmp(request.getMethod(),"GET") && request.getParameter("notifying")) {
 241
 242         // This is returning from a front-channel notification, so we have to do the back-channel and then
 243         // respond. To do that, we need state from the original request.
 244         if (!request.getParameter("entityID")) {
 245             if (session_id)
 246                 cache->remove(session_id, application);
 247             throw FatalProfileException("Application notification loop did not return entityID for LogoutResponse.");
 248         }
 249
 250         // Best effort on back channel and to remove the user agent's session.
 251         bool worked1 = false,worked2 = false;
 252         if (session_id) {
 253             vector<string> sessions(1,session_id);
 254             worked1 = notifyBackChannel(application, request.getRequestURL(), sessions, false);
 255             try {
 256                 cache->remove(session_id, application);
 257                 worked2 = true;
 258             }
 259             catch (exception& ex) {
 260                 m_log.error("error removing session (%s): %s", session_id, ex.what());
 261             }
 262         }
 263         else {
 264             worked1 = worked2 = true;
 265         }
 266
 267         // We need metadata to issue a response.
 268         Locker metadataLocker(application.getMetadataProvider());
 269         const EntityDescriptor* entity = application.getMetadataProvider()->getEntityDescriptor(request.getParameter("entityID"));
 270         if (!entity) {
 271             throw MetadataException(
 272                 "Unable to locate metadata for identity provider ($entityID)", namedparams(1, "entityID", request.getParameter("entityID"))
 273                 );
 274         }
 275         const IDPSSODescriptor* idp = entity->getIDPSSODescriptor(samlconstants::SAML20P_NS);
 276         if (!idp) {
 277             throw MetadataException(
 278                 "Unable to locate SAML 2.0 IdP role for identity provider ($entityID).",
 279                 namedparams(1, "entityID", request.getParameter("entityID"))
 280                 );
 281         }
 282
 283         auto_ptr_XMLCh reqid(request.getParameter("ID"));
 284         if (worked1 && worked2) {
 285             // Successful LogoutResponse. Has to be front-channel or we couldn't be here.
 286             return sendResponse(
 287                 reqid.get(), StatusCode::SUCCESS, NULL, NULL, request.getParameter("RelayState"), idp, application, response, true
 288                 );
 289         }
 290
 291         return sendResponse(
 292             reqid.get(),
 293             StatusCode::RESPONDER, NULL, "Unable to fully destroy principal's session.",
 294             request.getParameter("RelayState"),
 295             idp,
 296             application,
 297             response,
 298             true
 299             );
 300     }
 301
 302     // If we get here, it's an external protocol message to decode.
 303
 304     // Locate policy key.
 305     pair<bool,const char*> policyId = getString("policyId", m_configNS.get());  // namespace-qualified if inside handler element
 306     if (!policyId.first)
 307         policyId = application.getString("policyId");   // unqualified in Application(s) element
 308
 309     // Access policy properties.
 310     const PropertySet* settings = application.getServiceProvider().getPolicySettings(policyId.second);
 311     pair<bool,bool> validate = settings->getBool("validate");
 312
 313     // Lock metadata for use by policy.
 314     Locker metadataLocker(application.getMetadataProvider());
 315
 316     // Create the policy.
 317     shibsp::SecurityPolicy policy(application, &m_role, validate.first && validate.second);
 318
 319     // Decode the message.
 320     string relayState;
 321     auto_ptr<XMLObject> msg(m_decoder->decode(relayState, request, policy));
 322     const LogoutRequest* logoutRequest = dynamic_cast<LogoutRequest*>(msg.get());
 323     if (logoutRequest) {
 324         if (!policy.isSecure())
 325             throw SecurityPolicyException("Security of LogoutRequest not established.");
 326
 327         // Message from IdP to logout one or more sessions.
 328
 329         // If this is front-channel, we have to have a session_id to use already.
 330         if (m_decoder->isUserAgentPresent() && !session_id) {
 331             m_log.error("no active session");
 332             return sendResponse(
 333                 logoutRequest->getID(),
 334                 StatusCode::REQUESTER, StatusCode::UNKNOWN_PRINCIPAL, "No active session found in request.",
 335                 relayState.c_str(),
 336                 policy.getIssuerMetadata(),
 337                 application,
 338                 response,
 339                 true
 340                 );
 341         }
 342
 343         bool ownedName = false;
 344         NameID* nameid = logoutRequest->getNameID();
 345         if (!nameid) {
 346             // Check for EncryptedID.
 347             EncryptedID* encname = logoutRequest->getEncryptedID();
 348             if (encname) {
 349                 CredentialResolver* cr=application.getCredentialResolver();
 350                 if (!cr)
 351                     m_log.warn("found encrypted NameID, but no decryption credential was available");
 352                 else {
 353                     Locker credlocker(cr);
 354                     auto_ptr<MetadataCredentialCriteria> mcc(
 355                         policy.getIssuerMetadata() ? new MetadataCredentialCriteria(*policy.getIssuerMetadata()) : NULL
 356                         );
 357                     try {
 358                         auto_ptr<XMLObject> decryptedID(encname->decrypt(*cr,application.getXMLString("entityID").second,mcc.get()));
 359                         nameid = dynamic_cast<NameID*>(decryptedID.get());
 360                         if (nameid) {
 361                             ownedName = true;
 362                             decryptedID.release();
 363                         }
 364                     }
 365                     catch (exception& ex) {
 366                         m_log.error(ex.what());
 367                     }
 368                 }
 369             }
 370         }
 371         if (!nameid) {
 372             // No NameID, so must respond with an error.
 373             m_log.error("NameID not found in request");
 374             return sendResponse(
 375                 logoutRequest->getID(),
 376                 StatusCode::REQUESTER, StatusCode::UNKNOWN_PRINCIPAL, "NameID not found in request.",
 377                 relayState.c_str(),
 378                 policy.getIssuerMetadata(),
 379                 application,
 380                 response,
 381                 m_decoder->isUserAgentPresent()
 382                 );
 383         }
 384
 385         // Suck indexes out of the request for next steps.
 386         set<string> indexes;
 387         EntityDescriptor* entity = policy.getIssuerMetadata() ? dynamic_cast<EntityDescriptor*>(policy.getIssuerMetadata()->getParent()) : NULL;
 388         const vector<SessionIndex*> sindexes = logoutRequest->getSessionIndexs();
 389         for (vector<SessionIndex*>::const_iterator i = sindexes.begin(); i != sindexes.end(); ++i) {
 390             auto_ptr_char sindex((*i)->getSessionIndex());
 391             indexes.insert(sindex.get());
 392         }
 393
 394         // For a front-channel LogoutRequest, we have to match the information in the request
 395         // against the current session.
 396         if (session_id) {
 397             if (!cache->matches(session_id, entity, *nameid, &indexes, application)) {
 398                 return sendResponse(
 399                     logoutRequest->getID(),
 400                     StatusCode::REQUESTER, StatusCode::REQUEST_DENIED, "Active sessions did not match logout request.",
 401                     relayState.c_str(),
 402                     policy.getIssuerMetadata(),
 403                     application,
 404                     response,
 405                     true
 406                     );
 407             }
 408
 409         }
 410
 411         // Now we perform "logout" by finding the matching sessions.
 412         vector<string> sessions;
 413         try {
 414             time_t expires = logoutRequest->getNotOnOrAfter() ? logoutRequest->getNotOnOrAfterEpoch() : 0;
 415             cache->logout(entity, *nameid, &indexes, expires, application, sessions);
 416
 417             // Now we actually terminate everything except for the active session,
 418             // if this is front-channel, for notification purposes.
 419             for (vector<string>::const_iterator sit = sessions.begin(); sit != sessions.end(); ++sit)
 420                 if (session_id && strcmp(sit->c_str(), session_id))
 421                     cache->remove(sit->c_str(), application);
 422         }
 423         catch (exception& ex) {
 424             m_log.error("error while logging out matching sessions: %s", ex.what());
 425             return sendResponse(
 426                 logoutRequest->getID(),
 427                 StatusCode::RESPONDER, NULL, ex.what(),
 428                 relayState.c_str(),
 429                 policy.getIssuerMetadata(),
 430                 application,
 431                 response,
 432                 m_decoder->isUserAgentPresent()
 433                 );
 434         }
 435
 436         if (m_decoder->isUserAgentPresent()) {
 437             // Pass control to the first front channel notification point, if any.
 438             map<string,string> parammap;
 439             if (!relayState.empty())
 440                 parammap["RelayState"] = relayState;
 441             auto_ptr_char entityID(entity ? entity->getEntityID() : NULL);
 442             if (entityID.get())
 443                 parammap["entityID"] = entityID.get();
 444             auto_ptr_char reqID(logoutRequest->getID());
 445             if (reqID.get())
 446                 parammap["ID"] = reqID.get();
 447             pair<bool,long> result = notifyFrontChannel(application, request, response, &parammap);
 448             if (result.first)
 449                 return result;
 450         }
 451
 452         // For back-channel requests, or if no front-channel notification is needed...
 453         bool worked1 = false,worked2 = false;
 454         worked1 = notifyBackChannel(application, request.getRequestURL(), sessions, false);
 455         if (session_id) {
 456             // One last session to yoink...
 457             try {
 458                 cache->remove(session_id, application);
 459                 worked2 = true;
 460             }
 461             catch (exception& ex) {
 462                 m_log.error("error removing active session (%s): %s", session_id, ex.what());
 463             }
 464         }
 465
 466         return sendResponse(
 467             logoutRequest->getID(),
 468             (worked1 && worked2) ? StatusCode::SUCCESS : StatusCode::RESPONDER,
 469             (worked1 && worked2) ? NULL : StatusCode::PARTIAL_LOGOUT,
 470             NULL,
 471             relayState.c_str(),
 472             policy.getIssuerMetadata(),
 473             application,
 474             response,
 475             m_decoder->isUserAgentPresent()
 476             );
 477     }
 478
 479     // A LogoutResponse completes an SP-initiated logout sequence.
 480     const LogoutResponse* logoutResponse = dynamic_cast<LogoutResponse*>(msg.get());
 481     if (logoutResponse) {
 482         if (!policy.isSecure()) {
 483             SecurityPolicyException ex("Security of LogoutResponse not established.");
 484             if (policy.getIssuerMetadata())
 485                 annotateException(&ex, policy.getIssuerMetadata()); // throws it
 486             ex.raise();
 487         }
 488         checkError(logoutResponse, policy.getIssuerMetadata()); // throws if Status doesn't look good...
 489
 490         // Return template for completion of global logout, or redirect to homeURL.
 491         return sendLogoutPage(application, response, false, "Global logout completed.");
 492     }
 493
 494     FatalProfileException ex("Incoming message was not a samlp:LogoutRequest or samlp:LogoutResponse.");
 495     if (policy.getIssuerMetadata())
 496         annotateException(&ex, policy.getIssuerMetadata()); // throws it
 497     ex.raise();
 498     return make_pair(false,0);  // never happen, satisfies compiler
 499 #else
 500     throw ConfigurationException("Cannot process logout message using lite version of shibsp library.");
 501 #endif
 502 }
 503
 504 #ifndef SHIBSP_LITE
 505
 506 bool SAML2Logout::stronglyMatches(const XMLCh* idp, const XMLCh* sp, const saml2::NameID& n1, const saml2::NameID& n2) const
 507 {
 508     if (!XMLString::equals(n1.getName(), n2.getName()))
 509         return false;
 510
 511     const XMLCh* s1 = n1.getFormat();
 512     const XMLCh* s2 = n2.getFormat();
 513     if (!s1 || !*s1)
 514         s1 = saml2::NameID::UNSPECIFIED;
 515     if (!s2 || !*s2)
 516         s2 = saml2::NameID::UNSPECIFIED;
 517     if (!XMLString::equals(s1,s2))
 518         return false;
 519
 520     s1 = n1.getNameQualifier();
 521     s2 = n2.getNameQualifier();
 522     if (!s1 || !*s1)
 523         s1 = idp;
 524     if (!s2 || !*s2)
 525         s2 = idp;
 526     if (!XMLString::equals(s1,s2))
 527         return false;
 528
 529     s1 = n1.getSPNameQualifier();
 530     s2 = n2.getSPNameQualifier();
 531     if (!s1 || !*s1)
 532         s1 = sp;
 533     if (!s2 || !*s2)
 534         s2 = sp;
 535     if (!XMLString::equals(s1,s2))
 536         return false;
 537
 538     return true;
 539 }
 540
 541 pair<bool,long> SAML2Logout::sendResponse(
 542     const XMLCh* requestID,
 543     const XMLCh* code,
 544     const XMLCh* subcode,
 545     const char* msg,
 546     const char* relayState,
 547     const RoleDescriptor* role,
 548     const Application& application,
 549     HTTPResponse& httpResponse,
 550     bool front
 551     ) const
 552 {
 553     // Get endpoint and encoder to use.
 554     const EndpointType* ep = NULL;
 555     const MessageEncoder* encoder = NULL;
 556     if (front) {
 557         const IDPSSODescriptor* idp = dynamic_cast<const IDPSSODescriptor*>(role);
 558         for (vector<const XMLCh*>::const_iterator b = m_bindings.begin(); idp && b!=m_bindings.end(); ++b) {
 559             if (ep=EndpointManager<SingleLogoutService>(idp->getSingleLogoutServices()).getByBinding(*b)) {
 560                 map<const XMLCh*,MessageEncoder*>::const_iterator enc = m_encoders.find(*b);
 561                 if (enc!=m_encoders.end())
 562                     encoder = enc->second;
 563                 break;
 564             }
 565         }
 566         if (!ep || !encoder) {
 567             auto_ptr_char id(dynamic_cast<EntityDescriptor*>(role->getParent())->getEntityID());
 568             m_log.error("unable to locate compatible SLO service for provider (%s)", id.get());
 569             MetadataException ex("Unable to locate endpoint at IdP ($entityID) to send LogoutResponse.");
 570             annotateException(&ex, role);   // throws it
 571         }
 572     }
 573     else {
 574         encoder = m_encoders.begin()->second;
 575     }
 576
 577     // Prepare response.
 578     auto_ptr<LogoutResponse> logout(LogoutResponseBuilder::buildLogoutResponse());
 579     logout->setInResponseTo(requestID);
 580     if (ep)
 581         logout->setDestination(ep->getLocation());
 582     Issuer* issuer = IssuerBuilder::buildIssuer();
 583     logout->setIssuer(issuer);
 584     issuer->setName(application.getXMLString("entityID").second);
 585     fillStatus(*logout.get(), code, subcode, msg);
 586
 587     auto_ptr_char dest(ep ? ep->getLocation() : NULL);
 588
 589     long ret = sendMessage(*encoder, logout.get(), relayState, dest.get(), role, application, httpResponse, "signResponses");
 590     logout.release();  // freed by encoder
 591     return make_pair(true,ret);
 592 }
 593
 594 #endif