xmltooling/security/impl/PKIXPathValidator.cpp

   1 /**
   2  * Licensed to the University Corporation for Advanced Internet
   3  * Development, Inc. (UCAID) under one or more contributor license
   4  * agreements. See the NOTICE file distributed with this work for
   5  * additional information regarding copyright ownership.
   6  *
   7  * UCAID licenses this file to you under the Apache License,
   8  * Version 2.0 (the "License"); you may not use this file except
   9  * in compliance with the License. You may obtain a copy of the
  10  * License at
  11  *
  12  * http://www.apache.org/licenses/LICENSE-2.0
  13  *
  14  * Unless required by applicable law or agreed to in writing,
  15  * software distributed under the License is distributed on an
  16  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
  17  * either express or implied. See the License for the specific
  18  * language governing permissions and limitations under the License.
  19  */
  20
  21 /**
  22  * PKIXPathValidator.cpp
  23  *
  24  * A path validator based on PKIX support in OpenSSL.
  25  */
  26
  27 #include "internal.h"
  28 #include "logging.h"
  29 #include "security/OpenSSLPathValidator.h"
  30 #include "security/OpenSSLCryptoX509CRL.h"
  31 #include "security/PKIXPathValidatorParams.h"
  32 #include "security/SecurityHelper.h"
  33 #include "util/NDC.h"
  34 #include "util/PathResolver.h"
  35 #include "util/Threads.h"
  36 #include "util/XMLHelper.h"
  37
  38 #include <algorithm>
  39 #include <fstream>
  40 #include <openssl/x509_vfy.h>
  41 #include <openssl/x509v3.h>
  42 #include <xsec/enc/OpenSSL/OpenSSLCryptoX509.hpp>
  43
  44 using namespace xmltooling::logging;
  45 using namespace xmltooling;
  46 using namespace std;
  47
  48
  49 namespace {
  50     static int XMLTOOL_DLLLOCAL error_callback(int ok, X509_STORE_CTX* ctx)
  51     {
  52         if (!ok)
  53             Category::getInstance("OpenSSL").error("path validation failure: %s", X509_verify_cert_error_string(ctx->error));
  54         return ok;
  55     }
  56
  57     static string XMLTOOL_DLLLOCAL X509_NAME_to_string(X509_NAME* n)
  58     {
  59         string s;
  60         BIO* b = BIO_new(BIO_s_mem());
  61         X509_NAME_print_ex(b,n,0,XN_FLAG_RFC2253);
  62         BIO_flush(b);
  63         BUF_MEM* bptr=nullptr;
  64         BIO_get_mem_ptr(b, &bptr);
  65         if (bptr && bptr->length > 0) {
  66             s.append(bptr->data, bptr->length);
  67         }
  68         BIO_free(b);
  69         return s;
  70     }
  71
  72     static time_t XMLTOOL_DLLLOCAL getCRLTime(const ASN1_TIME *a)
  73     {
  74         struct tm t;
  75         memset(&t, 0, sizeof(t));
  76         // RFC 5280, sections 5.1.2.4 and 5.1.2.5 require thisUpdate and nextUpdate
  77         // to be encoded as UTCTime until 2049, and RFC 5280 section 4.1.2.5.1
  78         // further restricts the format to "YYMMDDHHMMSSZ" ("even where the number
  79         // of seconds is zero").
  80         // As long as OpenSSL doesn't provide any API to convert ASN1_TIME values
  81         // time_t, we therefore have to parse it ourselves, unfortunately.
  82         if (sscanf((const char*)a->data, "%2d%2d%2d%2d%2d%2dZ",
  83             &t.tm_year, &t.tm_mon, &t.tm_mday,
  84             &t.tm_hour, &t.tm_min, &t.tm_sec) == 6) {
  85             if (t.tm_year <= 50) {
  86                 // RFC 5280, section 4.1.2.5.1
  87                 t.tm_year += 100;
  88             }
  89             t.tm_mon--;
  90 #if defined(HAVE_TIMEGM)
  91             return timegm(&t);
  92 #else
  93             // Windows, and hopefully most others...?
  94             return mktime(&t) - timezone;
  95 #endif
  96         }
  97         return (time_t)-1;
  98     }
  99
 100     static const XMLCh minRefreshDelay[] =      UNICODE_LITERAL_15(m,i,n,R,e,f,r,e,s,h,D,e,l,a,y);
 101     static const XMLCh minSecondsRemaining[] =  UNICODE_LITERAL_19(m,i,n,S,e,c,o,n,d,s,R,e,m,a,i,n,i,n,g);
 102     static const XMLCh minPercentRemaining[] =  UNICODE_LITERAL_19(m,i,n,P,e,r,c,e,n,t,R,e,m,a,i,n,i,n,g);
 103 };
 104
 105 namespace xmltooling {
 106
 107     class XMLTOOL_DLLLOCAL PKIXPathValidator : public OpenSSLPathValidator
 108     {
 109     public:
 110         PKIXPathValidator(const xercesc::DOMElement* e)
 111             : m_log(Category::getInstance(XMLTOOLING_LOGCAT".PathValidator.PKIX")),
 112               m_lock(XMLToolingConfig::getConfig().getNamedMutex(XMLTOOLING_LOGCAT".PathValidator.PKIX")),
 113               m_minRefreshDelay(XMLHelper::getAttrInt(e, 60, minRefreshDelay)),
 114               m_minSecondsRemaining(XMLHelper::getAttrInt(e, 86400, minSecondsRemaining)),
 115               m_minPercentRemaining(XMLHelper::getAttrInt(e, 10, minPercentRemaining)) {
 116         }
 117
 118         virtual ~PKIXPathValidator() {}
 119
 120         bool validate(
 121             XSECCryptoX509* certEE, const vector<XSECCryptoX509*>& certChain, const PathValidatorParams& params
 122             ) const;
 123         bool validate(
 124             X509* certEE, STACK_OF(X509)* certChain, const PathValidatorParams& params
 125             ) const;
 126
 127     private:
 128         XSECCryptoX509CRL* getRemoteCRLs(const char* cdpuri) const;
 129         bool isFreshCRL(XSECCryptoX509CRL *c, Category* log=nullptr) const;
 130
 131         Category& m_log;
 132         Mutex& m_lock;
 133         time_t m_minRefreshDelay,m_minSecondsRemaining;
 134         unsigned short m_minPercentRemaining;
 135
 136         static map<string,time_t> m_crlUpdateMap;
 137     };
 138
 139     PathValidator* XMLTOOL_DLLLOCAL PKIXPathValidatorFactory(const xercesc::DOMElement* const & e)
 140     {
 141         return new PKIXPathValidator(e);
 142     }
 143
 144 };
 145
 146 map<string,time_t> PKIXPathValidator::m_crlUpdateMap;
 147
 148 void XMLTOOL_API xmltooling::registerPathValidators()
 149 {
 150     XMLToolingConfig& conf=XMLToolingConfig::getConfig();
 151     conf.PathValidatorManager.registerFactory(PKIX_PATHVALIDATOR, PKIXPathValidatorFactory);
 152 }
 153
 154 PathValidator::PathValidator()
 155 {
 156 }
 157
 158 PathValidator::~PathValidator()
 159 {
 160 }
 161
 162 PathValidator::PathValidatorParams::PathValidatorParams()
 163 {
 164 }
 165
 166 PathValidator::PathValidatorParams::~PathValidatorParams()
 167 {
 168 }
 169
 170 PKIXPathValidatorParams::PKIXPathValidatorParams()
 171 {
 172 }
 173
 174 PKIXPathValidatorParams::~PKIXPathValidatorParams()
 175 {
 176 }
 177
 178 OpenSSLPathValidator::OpenSSLPathValidator()
 179 {
 180 }
 181
 182 OpenSSLPathValidator::~OpenSSLPathValidator()
 183 {
 184 }
 185
 186 bool PKIXPathValidator::validate(
 187     XSECCryptoX509* certEE, const vector<XSECCryptoX509*>& certChain, const PathValidatorParams& params
 188     ) const
 189 {
 190     if (certEE->getProviderName()!=DSIGConstants::s_unicodeStrPROVOpenSSL) {
 191         m_log.error("only the OpenSSL XSEC provider is supported");
 192         return false;
 193     }
 194
 195     STACK_OF(X509)* untrusted=sk_X509_new_null();
 196     for (vector<XSECCryptoX509*>::const_iterator i=certChain.begin(); i!=certChain.end(); ++i)
 197         sk_X509_push(untrusted,static_cast<OpenSSLCryptoX509*>(*i)->getOpenSSLX509());
 198
 199     bool ret = validate(static_cast<OpenSSLCryptoX509*>(certEE)->getOpenSSLX509(), untrusted, params);
 200     sk_X509_free(untrusted);
 201     return ret;
 202 }
 203
 204 bool PKIXPathValidator::validate(X509* EE, STACK_OF(X509)* untrusted, const PathValidatorParams& params) const
 205 {
 206 #ifdef _DEBUG
 207     NDC ndc("validate");
 208 #endif
 209
 210     const PKIXPathValidatorParams* pkixParams = dynamic_cast<const PKIXPathValidatorParams*>(&params);
 211     if (!pkixParams) {
 212         m_log.error("input parameters were of incorrect type");
 213         return false;
 214     }
 215
 216     // First we build a stack of CA certs. These objects are all referenced in place.
 217     m_log.debug("supplying PKIX Validation information");
 218
 219     // We need this for CRL support.
 220     X509_STORE* store=X509_STORE_new();
 221     if (!store) {
 222         log_openssl();
 223         return false;
 224     }
 225
 226     // PKIX policy checking (cf. RFCs 3280/5280 section 6)
 227     if (pkixParams->isPolicyMappingInhibited() || pkixParams->isAnyPolicyInhibited() || (!pkixParams->getPolicies().empty())) {
 228 #if (OPENSSL_VERSION_NUMBER < 0x00908000L)
 229         m_log.error("PKIX policy checking option is configured, but OpenSSL version is less than 0.9.8");
 230         X509_STORE_free(store);
 231         return false;
 232 #else
 233         unsigned long pflags = 0;
 234         X509_VERIFY_PARAM *vpm = X509_VERIFY_PARAM_new();
 235         if (!vpm) {
 236             log_openssl();
 237             X509_STORE_free(store);
 238             return false;
 239         }
 240
 241         // populate the "user-initial-policy-set" input variable
 242         const set<string>& policies = pkixParams->getPolicies();
 243         if (!policies.empty()) {
 244             for (set<string>::const_iterator o=policies.begin(); o!=policies.end(); o++) {
 245                 ASN1_OBJECT *oid = OBJ_txt2obj(o->c_str(), 1);
 246                 if (oid && X509_VERIFY_PARAM_add0_policy(vpm, oid)) {
 247                     m_log.debug("OID (%s) added to set of acceptable policies", o->c_str());
 248                 }
 249                 else {
 250                     log_openssl();
 251                     m_log.error("unable to parse/configure policy OID value (%s)", o->c_str());
 252                     if (oid)
 253                         ASN1_OBJECT_free(oid);
 254                     X509_VERIFY_PARAM_free(vpm);
 255                     X509_STORE_free(store);
 256                     return false;
 257                 }
 258             }
 259             // when the user has supplied at least one policy OID, he obviously wants to check
 260             // for an explicit policy ("initial-explicit-policy")
 261             pflags |= X509_V_FLAG_EXPLICIT_POLICY;
 262         }
 263
 264         // "initial-policy-mapping-inhibit" input variable
 265         if (pkixParams->isPolicyMappingInhibited())
 266             pflags |= X509_V_FLAG_INHIBIT_MAP;
 267         // "initial-any-policy-inhibit" input variable
 268         if (pkixParams->isAnyPolicyInhibited())
 269             pflags |= X509_V_FLAG_INHIBIT_ANY;
 270
 271         if (!X509_VERIFY_PARAM_set_flags(vpm, pflags) || !X509_STORE_set1_param(store, vpm)) {
 272             log_openssl();
 273             m_log.error("unable to set PKIX policy checking parameters");
 274             X509_VERIFY_PARAM_free(vpm);
 275             X509_STORE_free(store);
 276             return false;
 277         }
 278
 279         X509_VERIFY_PARAM_free(vpm);
 280 #endif
 281     }
 282
 283     // This contains the state of the validate operation.
 284     int count=0;
 285     X509_STORE_CTX ctx;
 286
 287     // AFAICT, EE and untrusted are passed in but not owned by the ctx.
 288 #if (OPENSSL_VERSION_NUMBER >= 0x00907000L)
 289     if (X509_STORE_CTX_init(&ctx,store,EE,untrusted)!=1) {
 290         log_openssl();
 291         m_log.error("unable to initialize X509_STORE_CTX");
 292         X509_STORE_free(store);
 293         return false;
 294     }
 295 #else
 296     X509_STORE_CTX_init(&ctx,store,EE,untrusted);
 297 #endif
 298
 299     STACK_OF(X509)* CAstack = sk_X509_new_null();
 300     const vector<XSECCryptoX509*>& CAcerts = pkixParams->getTrustAnchors();
 301     for (vector<XSECCryptoX509*>::const_iterator i=CAcerts.begin(); i!=CAcerts.end(); ++i) {
 302         if ((*i)->getProviderName()==DSIGConstants::s_unicodeStrPROVOpenSSL) {
 303             sk_X509_push(CAstack,static_cast<OpenSSLCryptoX509*>(*i)->getOpenSSLX509());
 304             ++count;
 305         }
 306     }
 307     m_log.debug("supplied (%d) CA certificate(s)", count);
 308
 309     // Seems to be most efficient to just pass in the CA stack.
 310     X509_STORE_CTX_trusted_stack(&ctx,CAstack);
 311     X509_STORE_CTX_set_depth(&ctx,100);    // we check the depth down below
 312     X509_STORE_CTX_set_verify_cb(&ctx,error_callback);
 313
 314     // Do a first pass verify. If CRLs aren't used, this is the only pass.
 315     int ret=X509_verify_cert(&ctx);
 316     if (ret==1) {
 317         // Now see if the depth was acceptable by counting the number of intermediates.
 318         int depth=sk_X509_num(ctx.chain)-2;
 319         if (pkixParams->getVerificationDepth() < depth) {
 320             m_log.error(
 321                 "certificate chain was too long (%d intermediates, only %d allowed)",
 322                 (depth==-1) ? 0 : depth,
 323                 pkixParams->getVerificationDepth()
 324                 );
 325             ret=0;
 326         }
 327     }
 328
 329     if (pkixParams->getRevocationChecking() != PKIXPathValidatorParams::REVOCATION_OFF) {
 330 #if (OPENSSL_VERSION_NUMBER >= 0x00907000L)
 331         // When we add CRLs, we have to be sure the nextUpdate hasn't passed, because OpenSSL won't accept
 332         // the CRL in that case. If we end up not adding a CRL for a particular link in the chain, the
 333         // validation will fail (if the fullChain option was set).
 334         set<string> crlissuers;
 335         time_t now = time(nullptr);
 336
 337         const vector<XSECCryptoX509CRL*>& crls = pkixParams->getCRLs();
 338         for (vector<XSECCryptoX509CRL*>::const_iterator j=crls.begin(); j!=crls.end(); ++j) {
 339             if ((*j)->getProviderName()==DSIGConstants::s_unicodeStrPROVOpenSSL &&
 340                 (X509_cmp_time(X509_CRL_get_nextUpdate(static_cast<OpenSSLCryptoX509CRL*>(*j)->getOpenSSLX509CRL()), &now) > 0)) {
 341                 // owned by store
 342                 X509_STORE_add_crl(store, X509_CRL_dup(static_cast<OpenSSLCryptoX509CRL*>(*j)->getOpenSSLX509CRL()));
 343                 string crlissuer(X509_NAME_to_string(X509_CRL_get_issuer(static_cast<OpenSSLCryptoX509CRL*>(*j)->getOpenSSLX509CRL())));
 344                 if (!crlissuer.empty()) {
 345                     m_log.debug("added CRL issued by (%s)", crlissuer.c_str());
 346                     crlissuers.insert(crlissuer);
 347                 }
 348             }
 349         }
 350
 351         for (int i = 0; i < sk_X509_num(untrusted); ++i) {
 352             X509 *cert = sk_X509_value(untrusted, i);
 353             string crlissuer(X509_NAME_to_string(X509_get_issuer_name(cert)));
 354             if (crlissuers.count(crlissuer)) {
 355                // We already have a CRL for this cert, so skip CRLDP processing for this one.
 356                continue;
 357             }
 358
 359             bool foundUsableCDP = false;
 360             STACK_OF(DIST_POINT)* dps = (STACK_OF(DIST_POINT)*)X509_get_ext_d2i(cert, NID_crl_distribution_points, nullptr, nullptr);
 361             for (int ii = 0; !foundUsableCDP && ii < sk_DIST_POINT_num(dps); ++ii) {
 362                 DIST_POINT* dp = sk_DIST_POINT_value(dps, ii);
 363                 if (!dp->distpoint || dp->distpoint->type != 0)
 364                     continue;
 365                 for (int iii = 0; !foundUsableCDP && iii < sk_GENERAL_NAME_num(dp->distpoint->name.fullname); ++iii) {
 366                     GENERAL_NAME* gen = sk_GENERAL_NAME_value(dp->distpoint->name.fullname, iii);
 367                     // Only consider HTTP URIs, and stop after the first one we find.
 368 #ifdef HAVE_STRCASECMP
 369                     if (gen->type == GEN_URI && (!strncasecmp((const char*)gen->d.ia5->data, "http:", 5))) {
 370 #else
 371                     if (gen->type == GEN_URI && (!strnicmp((const char*)gen->d.ia5->data, "http:", 5))) {
 372 #endif
 373                         const char* cdpuri = (const char*)gen->d.ia5->data;
 374                         auto_ptr<XSECCryptoX509CRL> crl(getRemoteCRLs(cdpuri));
 375                         if (crl.get() && crl->getProviderName()==DSIGConstants::s_unicodeStrPROVOpenSSL &&
 376                             (isFreshCRL(crl.get()) || (ii == sk_DIST_POINT_num(dps)-1 && iii == sk_GENERAL_NAME_num(dp->distpoint->name.fullname)-1))) {
 377                             // owned by store
 378                             X509_STORE_add_crl(store, X509_CRL_dup(static_cast<OpenSSLCryptoX509CRL*>(crl.get())->getOpenSSLX509CRL()));
 379                             m_log.debug("added CRL issued by (%s)", crlissuer.c_str());
 380                             crlissuers.insert(crlissuer);
 381                             foundUsableCDP = true;
 382                         }
 383                     }
 384                 }
 385             }
 386             sk_DIST_POINT_free(dps);
 387         }
 388
 389         // Do a second pass verify with CRLs in place.
 390         if (pkixParams->getRevocationChecking() == PKIXPathValidatorParams::REVOCATION_FULLCHAIN)
 391             X509_STORE_CTX_set_flags(&ctx, X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
 392         else
 393             X509_STORE_CTX_set_flags(&ctx, X509_V_FLAG_CRL_CHECK);
 394         ret=X509_verify_cert(&ctx);
 395 #else
 396         m_log.warn("CRL checking is enabled, but OpenSSL version is too old");
 397         ret = 0;
 398 #endif
 399     }
 400
 401     // Clean up...
 402     X509_STORE_CTX_cleanup(&ctx);
 403     X509_STORE_free(store);
 404     sk_X509_free(CAstack);
 405
 406     if (ret==1) {
 407         m_log.debug("successfully validated certificate chain");
 408         return true;
 409     }
 410
 411     return false;
 412 }
 413
 414 XSECCryptoX509CRL* PKIXPathValidator::getRemoteCRLs(const char* cdpuri) const
 415 {
 416     // This is a filesystem-based CRL cache using a shared lock across all instances
 417     // of this class.
 418
 419     // The filenames for the CRL cache are based on a hash of the CRL location.
 420     string cdpfile = SecurityHelper::doHash("SHA1", cdpuri, strlen(cdpuri)) + ".crl";
 421     XMLToolingConfig::getConfig().getPathResolver()->resolve(cdpfile, PathResolver::XMLTOOLING_RUN_FILE);
 422     string cdpstaging = cdpfile + ".tmp";
 423
 424     time_t now = time(nullptr);
 425     vector<XSECCryptoX509CRL*> crls;
 426
 427     try {
 428         // While holding the lock, check for a cached copy of the CRL, and remove "expired" ones.
 429         Lock glock(m_lock);
 430 #ifdef WIN32
 431         struct _stat stat_buf;
 432         if (_stat(cdpfile.c_str(), &stat_buf) == 0) {
 433 #else
 434         struct stat stat_buf;
 435         if (stat(cdpfile.c_str(), &stat_buf) == 0) {
 436 #endif
 437             SecurityHelper::loadCRLsFromFile(crls, cdpfile.c_str());
 438             if (crls.empty() || crls.front()->getProviderName() != DSIGConstants::s_unicodeStrPROVOpenSSL ||
 439                 X509_cmp_time(X509_CRL_get_nextUpdate(static_cast<OpenSSLCryptoX509CRL*>(crls.front())->getOpenSSLX509CRL()), &now) < 0) {
 440                 for_each(crls.begin(), crls.end(), xmltooling::cleanup<XSECCryptoX509CRL>());
 441                 crls.clear();
 442                 remove(cdpfile.c_str());    // may as well delete the local copy
 443                 m_crlUpdateMap.erase(cdpuri);
 444                 m_log.info("deleting cached CRL from %s with nextUpdate field in the past", cdpuri);
 445             }
 446         }
 447     }
 448     catch (exception& ex) {
 449         m_log.error("exception loading cached copy of CRL from %s: %s", cdpuri, ex.what());
 450     }
 451
 452     if (crls.empty() || !isFreshCRL(crls.front(), &m_log)) {
 453         bool updateTimestamp = true;
 454         try {
 455             // If we get here, the cached copy didn't exist yet, or it's time to refresh.
 456             // To limit the rate of unsuccessful attempts when a CRLDP is unreachable,
 457             // we remember the timestamp of the last attempt (both successful/unsuccessful).
 458             time_t ts = 0;
 459             m_lock.lock();
 460             map<string,time_t>::const_iterator tsit = m_crlUpdateMap.find(cdpuri);
 461             if (tsit != m_crlUpdateMap.end())
 462                 ts = tsit->second;
 463             m_lock.unlock();
 464
 465             if (difftime(now, ts) > m_minRefreshDelay) {
 466                 SOAPTransport::Address addr("AbstractPKIXTrustEngine", cdpuri, cdpuri);
 467                 string scheme(addr.m_endpoint, strchr(addr.m_endpoint,':') - addr.m_endpoint);
 468                 auto_ptr<SOAPTransport> soap(XMLToolingConfig::getConfig().SOAPTransportManager.newPlugin(scheme.c_str(), addr));
 469                 soap->send();
 470                 istream& msg = soap->receive();
 471                 Lock glock(m_lock);
 472                 ofstream out(cdpstaging.c_str(), fstream::trunc|fstream::binary);
 473                 out << msg.rdbuf();
 474                 out.close();
 475                 SecurityHelper::loadCRLsFromFile(crls, cdpstaging.c_str());
 476                 if (crls.empty() || crls.front()->getProviderName() != DSIGConstants::s_unicodeStrPROVOpenSSL ||
 477                     X509_cmp_time(X509_CRL_get_nextUpdate(static_cast<OpenSSLCryptoX509CRL*>(crls.front())->getOpenSSLX509CRL()), &now) < 0) {
 478                     // The "new" CRL wasn't usable, so get rid of it.
 479                     for_each(crls.begin(), crls.end(), xmltooling::cleanup<XSECCryptoX509CRL>());
 480                     crls.clear();
 481                     remove(cdpstaging.c_str());
 482                     m_log.error("ignoring CRL retrieved from %s with nextUpdate field in the past", cdpuri);
 483                 }
 484                 else {
 485                     // "Commit" the new CRL. Note that we might add a CRL which doesn't pass
 486                     // isFreshCRL, but that's preferrable over adding none at all.
 487                     m_log.info("CRL refreshed from %s", cdpuri);
 488                     remove(cdpfile.c_str());
 489                     if (rename(cdpstaging.c_str(), cdpfile.c_str()) != 0)
 490                         m_log.error("unable to rename CRL staging file");
 491                 }
 492             }
 493             else {
 494                 updateTimestamp = false;    // don't update if we're within the backoff window
 495             }
 496         }
 497         catch (exception& ex) {
 498             m_log.error("exception downloading/caching CRL from %s: %s", cdpuri, ex.what());
 499         }
 500
 501         if (updateTimestamp) {
 502             Lock glock(m_lock);
 503             m_crlUpdateMap[cdpuri] = now;
 504         }
 505     }
 506
 507     if (crls.empty())
 508         return nullptr;
 509     for_each(crls.begin() + 1, crls.end(), xmltooling::cleanup<XSECCryptoX509CRL>());
 510     return crls.front();
 511 }
 512
 513 bool PKIXPathValidator::isFreshCRL(XSECCryptoX509CRL *c, Category* log) const
 514 {
 515     if (c) {
 516         const X509_CRL* crl = static_cast<OpenSSLCryptoX509CRL*>(c)->getOpenSSLX509CRL();
 517         time_t thisUpdate = getCRLTime(X509_CRL_get_lastUpdate(crl));
 518         time_t nextUpdate = getCRLTime(X509_CRL_get_nextUpdate(crl));
 519         time_t now = time(nullptr);
 520
 521         if (thisUpdate < 0 || nextUpdate < 0) {
 522             // we failed to parse at least one of the fields (they were not encoded
 523             // as required by RFC 5280, actually)
 524             time_t exp = now + m_minSecondsRemaining;
 525             if (log) {
 526                 log->warn("isFreshCRL (issuer '%s'): improperly encoded thisUpdate or nextUpdate field - falling back to simple time comparison",
 527                           (X509_NAME_to_string(X509_CRL_get_issuer(crl))).c_str());
 528             }
 529             return (X509_cmp_time(X509_CRL_get_nextUpdate(crl), &exp) > 0) ? true : false;
 530         }
 531         else {
 532             if (log && log->isDebugEnabled()) {
 533                 log->debug("isFreshCRL (issuer '%s'): %.0f seconds until nextUpdate (%3.2f%% elapsed since thisUpdate)",
 534                           (X509_NAME_to_string(X509_CRL_get_issuer(crl))).c_str(),
 535                           difftime(nextUpdate, now), (difftime(now, thisUpdate) * 100) / difftime(nextUpdate, thisUpdate));
 536             }
 537
 538             // consider it recent enough if there are at least MIN_SECS_REMAINING
 539             // to the nextUpdate, and at least MIN_PERCENT_REMAINING of its
 540             // overall "validity" are remaining to the nextUpdate
 541             return (now + m_minSecondsRemaining < nextUpdate) &&
 542                     ((difftime(nextUpdate, now) * 100) / difftime(nextUpdate, thisUpdate) > m_minPercentRemaining);
 543         }
 544     }
 545     return false;
 546 }