+/**
+ * Licensed to the University Corporation for Advanced Internet
+ * Development, Inc. (UCAID) under one or more contributor license
+ * agreements. See the NOTICE file distributed with this work for
+ * additional information regarding copyright ownership.
+ *
+ * UCAID licenses this file to you under the Apache License,
+ * Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the
+ * License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
+ * either express or implied. See the License for the specific
+ * language governing permissions and limitations under the License.
+ */
+
+/**
+ * PKIXPathValidator.cpp
+ *
+ * A path validator based on PKIX support in OpenSSL.
+ */
+
+#include "internal.h"
+#include "logging.h"
+#include "security/OpenSSLPathValidator.h"
+#include "security/OpenSSLCryptoX509CRL.h"
+#include "security/PKIXPathValidatorParams.h"
+#include "security/SecurityHelper.h"
+#include "util/NDC.h"
+#include "util/PathResolver.h"
+#include "util/Threads.h"
+#include "util/XMLHelper.h"
+
+#include <algorithm>
+#include <fstream>
+#include <openssl/x509_vfy.h>
+#include <openssl/x509v3.h>
+#include <xsec/enc/OpenSSL/OpenSSLCryptoX509.hpp>
+
+using namespace xmltooling::logging;
+using namespace xmltooling;
+using namespace std;
+
+
+namespace {
+ static int XMLTOOL_DLLLOCAL error_callback(int ok, X509_STORE_CTX* ctx)
+ {
+ if (!ok)
+ Category::getInstance("OpenSSL").error("path validation failure: %s", X509_verify_cert_error_string(ctx->error));
+ return ok;
+ }
+
+ static string XMLTOOL_DLLLOCAL X509_NAME_to_string(X509_NAME* n)
+ {
+ string s;
+ BIO* b = BIO_new(BIO_s_mem());
+ X509_NAME_print_ex(b,n,0,XN_FLAG_RFC2253);
+ BIO_flush(b);
+ BUF_MEM* bptr=nullptr;
+ BIO_get_mem_ptr(b, &bptr);
+ if (bptr && bptr->length > 0) {
+ s.append(bptr->data, bptr->length);
+ }
+ BIO_free(b);
+ return s;
+ }
+
+ static time_t XMLTOOL_DLLLOCAL getCRLTime(const ASN1_TIME *a)
+ {
+ struct tm t;
+ memset(&t, 0, sizeof(t));
+ // RFC 5280, sections 5.1.2.4 and 5.1.2.5 require thisUpdate and nextUpdate
+ // to be encoded as UTCTime until 2049, and RFC 5280 section 4.1.2.5.1
+ // further restricts the format to "YYMMDDHHMMSSZ" ("even where the number
+ // of seconds is zero").
+ // As long as OpenSSL doesn't provide any API to convert ASN1_TIME values
+ // time_t, we therefore have to parse it ourselves, unfortunately.
+ if (sscanf((const char*)a->data, "%2d%2d%2d%2d%2d%2dZ",
+ &t.tm_year, &t.tm_mon, &t.tm_mday,
+ &t.tm_hour, &t.tm_min, &t.tm_sec) == 6) {
+ if (t.tm_year <= 50) {
+ // RFC 5280, section 4.1.2.5.1
+ t.tm_year += 100;
+ }
+ t.tm_mon--;
+#if defined(HAVE_TIMEGM)
+ return timegm(&t);
+#else
+ // Windows, and hopefully most others...?
+ return mktime(&t) - timezone;
+#endif
+ }
+ return (time_t)-1;
+ }
+
+ static const XMLCh minRefreshDelay[] = UNICODE_LITERAL_15(m,i,n,R,e,f,r,e,s,h,D,e,l,a,y);
+ 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);
+ 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);
+};
+
+namespace xmltooling {
+
+ class XMLTOOL_DLLLOCAL PKIXPathValidator : public OpenSSLPathValidator
+ {
+ public:
+ PKIXPathValidator(const xercesc::DOMElement* e)
+ : m_log(Category::getInstance(XMLTOOLING_LOGCAT".PathValidator.PKIX")),
+ m_lock(XMLToolingConfig::getConfig().getNamedMutex(XMLTOOLING_LOGCAT".PathValidator.PKIX")),
+ m_minRefreshDelay(XMLHelper::getAttrInt(e, 60, minRefreshDelay)),
+ m_minSecondsRemaining(XMLHelper::getAttrInt(e, 86400, minSecondsRemaining)),
+ m_minPercentRemaining(XMLHelper::getAttrInt(e, 10, minPercentRemaining)) {
+ }
+
+ virtual ~PKIXPathValidator() {}
+
+ bool validate(
+ XSECCryptoX509* certEE, const vector<XSECCryptoX509*>& certChain, const PathValidatorParams& params
+ ) const;
+ bool validate(
+ X509* certEE, STACK_OF(X509)* certChain, const PathValidatorParams& params
+ ) const;
+
+ private:
+ XSECCryptoX509CRL* getRemoteCRLs(const char* cdpuri) const;
+ bool isFreshCRL(XSECCryptoX509CRL *c, Category* log=nullptr) const;
+
+ Category& m_log;
+ Mutex& m_lock;
+ time_t m_minRefreshDelay,m_minSecondsRemaining;
+ unsigned short m_minPercentRemaining;
+
+ static map<string,time_t> m_crlUpdateMap;
+ };
+
+ PathValidator* XMLTOOL_DLLLOCAL PKIXPathValidatorFactory(const xercesc::DOMElement* const & e)
+ {
+ return new PKIXPathValidator(e);
+ }
+
+};
+
+map<string,time_t> PKIXPathValidator::m_crlUpdateMap;
+
+void XMLTOOL_API xmltooling::registerPathValidators()
+{
+ XMLToolingConfig& conf=XMLToolingConfig::getConfig();
+ conf.PathValidatorManager.registerFactory(PKIX_PATHVALIDATOR, PKIXPathValidatorFactory);
+}
+
+PathValidator::PathValidator()
+{
+}
+
+PathValidator::~PathValidator()
+{
+}
+
+PathValidator::PathValidatorParams::PathValidatorParams()
+{
+}
+
+PathValidator::PathValidatorParams::~PathValidatorParams()
+{
+}
+
+PKIXPathValidatorParams::PKIXPathValidatorParams()
+{
+}
+
+PKIXPathValidatorParams::~PKIXPathValidatorParams()
+{
+}
+
+OpenSSLPathValidator::OpenSSLPathValidator()
+{
+}
+
+OpenSSLPathValidator::~OpenSSLPathValidator()
+{
+}
+
+bool PKIXPathValidator::validate(
+ XSECCryptoX509* certEE, const vector<XSECCryptoX509*>& certChain, const PathValidatorParams& params
+ ) const
+{
+ if (certEE->getProviderName()!=DSIGConstants::s_unicodeStrPROVOpenSSL) {
+ m_log.error("only the OpenSSL XSEC provider is supported");
+ return false;
+ }
+
+ STACK_OF(X509)* untrusted=sk_X509_new_null();
+ for (vector<XSECCryptoX509*>::const_iterator i=certChain.begin(); i!=certChain.end(); ++i)
+ sk_X509_push(untrusted,static_cast<OpenSSLCryptoX509*>(*i)->getOpenSSLX509());
+
+ bool ret = validate(static_cast<OpenSSLCryptoX509*>(certEE)->getOpenSSLX509(), untrusted, params);
+ sk_X509_free(untrusted);
+ return ret;
+}
+
+bool PKIXPathValidator::validate(X509* EE, STACK_OF(X509)* untrusted, const PathValidatorParams& params) const
+{
+#ifdef _DEBUG
+ NDC ndc("validate");
+#endif
+
+ const PKIXPathValidatorParams* pkixParams = dynamic_cast<const PKIXPathValidatorParams*>(¶ms);
+ if (!pkixParams) {
+ m_log.error("input parameters were of incorrect type");
+ return false;
+ }
+
+ // First we build a stack of CA certs. These objects are all referenced in place.
+ m_log.debug("supplying PKIX Validation information");
+
+ // We need this for CRL support.
+ X509_STORE* store=X509_STORE_new();
+ if (!store) {
+ log_openssl();
+ return false;
+ }
+
+ // PKIX policy checking (cf. RFCs 3280/5280 section 6)
+ if (pkixParams->isPolicyMappingInhibited() || pkixParams->isAnyPolicyInhibited() || (!pkixParams->getPolicies().empty())) {
+#if (OPENSSL_VERSION_NUMBER < 0x00908000L)
+ m_log.error("PKIX policy checking option is configured, but OpenSSL version is less than 0.9.8");
+ X509_STORE_free(store);
+ return false;
+#else
+ unsigned long pflags = 0;
+ X509_VERIFY_PARAM *vpm = X509_VERIFY_PARAM_new();
+ if (!vpm) {
+ log_openssl();
+ X509_STORE_free(store);
+ return false;
+ }
+
+ // populate the "user-initial-policy-set" input variable
+ const set<string>& policies = pkixParams->getPolicies();
+ if (!policies.empty()) {
+ for (set<string>::const_iterator o=policies.begin(); o!=policies.end(); o++) {
+ ASN1_OBJECT *oid = OBJ_txt2obj(o->c_str(), 1);
+ if (oid && X509_VERIFY_PARAM_add0_policy(vpm, oid)) {
+ m_log.debug("OID (%s) added to set of acceptable policies", o->c_str());
+ }
+ else {
+ log_openssl();
+ m_log.error("unable to parse/configure policy OID value (%s)", o->c_str());
+ if (oid)
+ ASN1_OBJECT_free(oid);
+ X509_VERIFY_PARAM_free(vpm);
+ X509_STORE_free(store);
+ return false;
+ }
+ }
+ // when the user has supplied at least one policy OID, he obviously wants to check
+ // for an explicit policy ("initial-explicit-policy")
+ pflags |= X509_V_FLAG_EXPLICIT_POLICY;
+ }
+
+ // "initial-policy-mapping-inhibit" input variable
+ if (pkixParams->isPolicyMappingInhibited())
+ pflags |= X509_V_FLAG_INHIBIT_MAP;
+ // "initial-any-policy-inhibit" input variable
+ if (pkixParams->isAnyPolicyInhibited())
+ pflags |= X509_V_FLAG_INHIBIT_ANY;
+
+ if (!X509_VERIFY_PARAM_set_flags(vpm, pflags) || !X509_STORE_set1_param(store, vpm)) {
+ log_openssl();
+ m_log.error("unable to set PKIX policy checking parameters");
+ X509_VERIFY_PARAM_free(vpm);
+ X509_STORE_free(store);
+ return false;
+ }
+
+ X509_VERIFY_PARAM_free(vpm);
+#endif
+ }
+
+ // This contains the state of the validate operation.
+ int count=0;
+ X509_STORE_CTX ctx;
+
+ // AFAICT, EE and untrusted are passed in but not owned by the ctx.
+#if (OPENSSL_VERSION_NUMBER >= 0x00907000L)
+ if (X509_STORE_CTX_init(&ctx,store,EE,untrusted)!=1) {
+ log_openssl();
+ m_log.error("unable to initialize X509_STORE_CTX");
+ X509_STORE_free(store);
+ return false;
+ }
+#else
+ X509_STORE_CTX_init(&ctx,store,EE,untrusted);
+#endif
+
+ STACK_OF(X509)* CAstack = sk_X509_new_null();
+ const vector<XSECCryptoX509*>& CAcerts = pkixParams->getTrustAnchors();
+ for (vector<XSECCryptoX509*>::const_iterator i=CAcerts.begin(); i!=CAcerts.end(); ++i) {
+ if ((*i)->getProviderName()==DSIGConstants::s_unicodeStrPROVOpenSSL) {
+ sk_X509_push(CAstack,static_cast<OpenSSLCryptoX509*>(*i)->getOpenSSLX509());
+ ++count;
+ }
+ }
+ m_log.debug("supplied (%d) CA certificate(s)", count);
+
+ // Seems to be most efficient to just pass in the CA stack.
+ X509_STORE_CTX_trusted_stack(&ctx,CAstack);
+ X509_STORE_CTX_set_depth(&ctx,100); // we check the depth down below
+ X509_STORE_CTX_set_verify_cb(&ctx,error_callback);
+
+ // Do a first pass verify. If CRLs aren't used, this is the only pass.
+ int ret=X509_verify_cert(&ctx);
+ if (ret==1) {
+ // Now see if the depth was acceptable by counting the number of intermediates.
+ int depth=sk_X509_num(ctx.chain)-2;
+ if (pkixParams->getVerificationDepth() < depth) {
+ m_log.error(
+ "certificate chain was too long (%d intermediates, only %d allowed)",
+ (depth==-1) ? 0 : depth,
+ pkixParams->getVerificationDepth()
+ );
+ ret=0;
+ }
+ }
+
+ if (pkixParams->getRevocationChecking() != PKIXPathValidatorParams::REVOCATION_OFF) {
+#if (OPENSSL_VERSION_NUMBER >= 0x00907000L)
+ // When we add CRLs, we have to be sure the nextUpdate hasn't passed, because OpenSSL won't accept
+ // the CRL in that case. If we end up not adding a CRL for a particular link in the chain, the
+ // validation will fail (if the fullChain option was set).
+ set<string> crlissuers;
+ time_t now = time(nullptr);
+
+ const vector<XSECCryptoX509CRL*>& crls = pkixParams->getCRLs();
+ for (vector<XSECCryptoX509CRL*>::const_iterator j=crls.begin(); j!=crls.end(); ++j) {
+ if ((*j)->getProviderName()==DSIGConstants::s_unicodeStrPROVOpenSSL &&
+ (X509_cmp_time(X509_CRL_get_nextUpdate(static_cast<OpenSSLCryptoX509CRL*>(*j)->getOpenSSLX509CRL()), &now) > 0)) {
+ // owned by store
+ X509_STORE_add_crl(store, X509_CRL_dup(static_cast<OpenSSLCryptoX509CRL*>(*j)->getOpenSSLX509CRL()));
+ string crlissuer(X509_NAME_to_string(X509_CRL_get_issuer(static_cast<OpenSSLCryptoX509CRL*>(*j)->getOpenSSLX509CRL())));
+ if (!crlissuer.empty()) {
+ m_log.debug("added CRL issued by (%s)", crlissuer.c_str());
+ crlissuers.insert(crlissuer);
+ }
+ }
+ }
+
+ for (int i = 0; i < sk_X509_num(untrusted); ++i) {
+ X509 *cert = sk_X509_value(untrusted, i);
+ string crlissuer(X509_NAME_to_string(X509_get_issuer_name(cert)));
+ if (crlissuers.count(crlissuer)) {
+ // We already have a CRL for this cert, so skip CRLDP processing for this one.
+ continue;
+ }
+
+ bool foundUsableCDP = false;
+ STACK_OF(DIST_POINT)* dps = (STACK_OF(DIST_POINT)*)X509_get_ext_d2i(cert, NID_crl_distribution_points, nullptr, nullptr);
+ for (int ii = 0; !foundUsableCDP && ii < sk_DIST_POINT_num(dps); ++ii) {
+ DIST_POINT* dp = sk_DIST_POINT_value(dps, ii);
+ if (!dp->distpoint || dp->distpoint->type != 0)
+ continue;
+ for (int iii = 0; !foundUsableCDP && iii < sk_GENERAL_NAME_num(dp->distpoint->name.fullname); ++iii) {
+ GENERAL_NAME* gen = sk_GENERAL_NAME_value(dp->distpoint->name.fullname, iii);
+ // Only consider HTTP URIs, and stop after the first one we find.
+#ifdef HAVE_STRCASECMP
+ if (gen->type == GEN_URI && (!strncasecmp((const char*)gen->d.ia5->data, "http:", 5))) {
+#else
+ if (gen->type == GEN_URI && (!strnicmp((const char*)gen->d.ia5->data, "http:", 5))) {
+#endif
+ const char* cdpuri = (const char*)gen->d.ia5->data;
+ auto_ptr<XSECCryptoX509CRL> crl(getRemoteCRLs(cdpuri));
+ if (crl.get() && crl->getProviderName()==DSIGConstants::s_unicodeStrPROVOpenSSL &&
+ (isFreshCRL(crl.get()) || (ii == sk_DIST_POINT_num(dps)-1 && iii == sk_GENERAL_NAME_num(dp->distpoint->name.fullname)-1))) {
+ // owned by store
+ X509_STORE_add_crl(store, X509_CRL_dup(static_cast<OpenSSLCryptoX509CRL*>(crl.get())->getOpenSSLX509CRL()));
+ m_log.debug("added CRL issued by (%s)", crlissuer.c_str());
+ crlissuers.insert(crlissuer);
+ foundUsableCDP = true;
+ }
+ }
+ }
+ }
+ sk_DIST_POINT_free(dps);
+ }
+
+ // Do a second pass verify with CRLs in place.
+ if (pkixParams->getRevocationChecking() == PKIXPathValidatorParams::REVOCATION_FULLCHAIN)
+ X509_STORE_CTX_set_flags(&ctx, X509_V_FLAG_CRL_CHECK|X509_V_FLAG_CRL_CHECK_ALL);
+ else
+ X509_STORE_CTX_set_flags(&ctx, X509_V_FLAG_CRL_CHECK);
+ ret=X509_verify_cert(&ctx);
+#else
+ m_log.warn("CRL checking is enabled, but OpenSSL version is too old");
+ ret = 0;
+#endif
+ }
+
+ // Clean up...
+ X509_STORE_CTX_cleanup(&ctx);
+ X509_STORE_free(store);
+ sk_X509_free(CAstack);
+
+ if (ret==1) {
+ m_log.debug("successfully validated certificate chain");
+ return true;
+ }
+
+ return false;
+}
+
+XSECCryptoX509CRL* PKIXPathValidator::getRemoteCRLs(const char* cdpuri) const
+{
+ // This is a filesystem-based CRL cache using a shared lock across all instances
+ // of this class.
+
+ // The filenames for the CRL cache are based on a hash of the CRL location.
+ string cdpfile = SecurityHelper::doHash("SHA1", cdpuri, strlen(cdpuri)) + ".crl";
+ XMLToolingConfig::getConfig().getPathResolver()->resolve(cdpfile, PathResolver::XMLTOOLING_RUN_FILE);
+ string cdpstaging = cdpfile + ".tmp";
+
+ time_t now = time(nullptr);
+ vector<XSECCryptoX509CRL*> crls;
+
+ try {
+ // While holding the lock, check for a cached copy of the CRL, and remove "expired" ones.
+ Lock glock(m_lock);
+#ifdef WIN32
+ struct _stat stat_buf;
+ if (_stat(cdpfile.c_str(), &stat_buf) == 0) {
+#else
+ struct stat stat_buf;
+ if (stat(cdpfile.c_str(), &stat_buf) == 0) {
+#endif
+ SecurityHelper::loadCRLsFromFile(crls, cdpfile.c_str());
+ if (crls.empty() || crls.front()->getProviderName() != DSIGConstants::s_unicodeStrPROVOpenSSL ||
+ X509_cmp_time(X509_CRL_get_nextUpdate(static_cast<OpenSSLCryptoX509CRL*>(crls.front())->getOpenSSLX509CRL()), &now) < 0) {
+ for_each(crls.begin(), crls.end(), xmltooling::cleanup<XSECCryptoX509CRL>());
+ crls.clear();
+ remove(cdpfile.c_str()); // may as well delete the local copy
+ m_crlUpdateMap.erase(cdpuri);
+ m_log.info("deleting cached CRL from %s with nextUpdate field in the past", cdpuri);
+ }
+ }
+ }
+ catch (exception& ex) {
+ m_log.error("exception loading cached copy of CRL from %s: %s", cdpuri, ex.what());
+ }
+
+ if (crls.empty() || !isFreshCRL(crls.front(), &m_log)) {
+ bool updateTimestamp = true;
+ try {
+ // If we get here, the cached copy didn't exist yet, or it's time to refresh.
+ // To limit the rate of unsuccessful attempts when a CRLDP is unreachable,
+ // we remember the timestamp of the last attempt (both successful/unsuccessful).
+ time_t ts = 0;
+ m_lock.lock();
+ map<string,time_t>::const_iterator tsit = m_crlUpdateMap.find(cdpuri);
+ if (tsit != m_crlUpdateMap.end())
+ ts = tsit->second;
+ m_lock.unlock();
+
+ if (difftime(now, ts) > m_minRefreshDelay) {
+ SOAPTransport::Address addr("AbstractPKIXTrustEngine", cdpuri, cdpuri);
+ string scheme(addr.m_endpoint, strchr(addr.m_endpoint,':') - addr.m_endpoint);
+ auto_ptr<SOAPTransport> soap(XMLToolingConfig::getConfig().SOAPTransportManager.newPlugin(scheme.c_str(), addr));
+ soap->send();
+ istream& msg = soap->receive();
+ Lock glock(m_lock);
+ ofstream out(cdpstaging.c_str(), fstream::trunc|fstream::binary);
+ out << msg.rdbuf();
+ out.close();
+ SecurityHelper::loadCRLsFromFile(crls, cdpstaging.c_str());
+ if (crls.empty() || crls.front()->getProviderName() != DSIGConstants::s_unicodeStrPROVOpenSSL ||
+ X509_cmp_time(X509_CRL_get_nextUpdate(static_cast<OpenSSLCryptoX509CRL*>(crls.front())->getOpenSSLX509CRL()), &now) < 0) {
+ // The "new" CRL wasn't usable, so get rid of it.
+ for_each(crls.begin(), crls.end(), xmltooling::cleanup<XSECCryptoX509CRL>());
+ crls.clear();
+ remove(cdpstaging.c_str());
+ m_log.error("ignoring CRL retrieved from %s with nextUpdate field in the past", cdpuri);
+ }
+ else {
+ // "Commit" the new CRL. Note that we might add a CRL which doesn't pass
+ // isFreshCRL, but that's preferrable over adding none at all.
+ m_log.info("CRL refreshed from %s", cdpuri);
+ remove(cdpfile.c_str());
+ if (rename(cdpstaging.c_str(), cdpfile.c_str()) != 0)
+ m_log.error("unable to rename CRL staging file");
+ }
+ }
+ else {
+ updateTimestamp = false; // don't update if we're within the backoff window
+ }
+ }
+ catch (exception& ex) {
+ m_log.error("exception downloading/caching CRL from %s: %s", cdpuri, ex.what());
+ }
+
+ if (updateTimestamp) {
+ Lock glock(m_lock);
+ m_crlUpdateMap[cdpuri] = now;
+ }
+ }
+
+ if (crls.empty())
+ return nullptr;
+ for_each(crls.begin() + 1, crls.end(), xmltooling::cleanup<XSECCryptoX509CRL>());
+ return crls.front();
+}
+
+bool PKIXPathValidator::isFreshCRL(XSECCryptoX509CRL *c, Category* log) const
+{
+ if (c) {
+ const X509_CRL* crl = static_cast<OpenSSLCryptoX509CRL*>(c)->getOpenSSLX509CRL();
+ time_t thisUpdate = getCRLTime(X509_CRL_get_lastUpdate(crl));
+ time_t nextUpdate = getCRLTime(X509_CRL_get_nextUpdate(crl));
+ time_t now = time(nullptr);
+
+ if (thisUpdate < 0 || nextUpdate < 0) {
+ // we failed to parse at least one of the fields (they were not encoded
+ // as required by RFC 5280, actually)
+ time_t exp = now + m_minSecondsRemaining;
+ if (log) {
+ log->warn("isFreshCRL (issuer '%s'): improperly encoded thisUpdate or nextUpdate field - falling back to simple time comparison",
+ (X509_NAME_to_string(X509_CRL_get_issuer(crl))).c_str());
+ }
+ return (X509_cmp_time(X509_CRL_get_nextUpdate(crl), &exp) > 0) ? true : false;
+ }
+ else {
+ if (log && log->isDebugEnabled()) {
+ log->debug("isFreshCRL (issuer '%s'): %.0f seconds until nextUpdate (%3.2f%% elapsed since thisUpdate)",
+ (X509_NAME_to_string(X509_CRL_get_issuer(crl))).c_str(),
+ difftime(nextUpdate, now), (difftime(now, thisUpdate) * 100) / difftime(nextUpdate, thisUpdate));
+ }
+
+ // consider it recent enough if there are at least MIN_SECS_REMAINING
+ // to the nextUpdate, and at least MIN_PERCENT_REMAINING of its
+ // overall "validity" are remaining to the nextUpdate
+ return (now + m_minSecondsRemaining < nextUpdate) &&
+ ((difftime(nextUpdate, now) * 100) / difftime(nextUpdate, thisUpdate) > m_minPercentRemaining);
+ }
+ }
+ return false;
+}