/*

  * This file is part of dependency-check-core.

  *

  * Licensed 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.

  *

  * Copyright (c) 2012 Jeremy Long. All Rights Reserved.

  */

 package org.owasp.dependencycheck.data.update;

 import java.net.MalformedURLException;

 import java.util.Calendar;

 import java.util.HashSet;

 import java.util.Set;

 import java.util.concurrent.ExecutionException;

 import java.util.concurrent.ExecutorService;

 import java.util.concurrent.Executors;

 import java.util.concurrent.Future;

 import org.owasp.dependencycheck.data.nvdcve.CveDB;

 import org.owasp.dependencycheck.data.nvdcve.DatabaseException;

 import org.owasp.dependencycheck.data.nvdcve.DatabaseProperties;

 import static org.owasp.dependencycheck.data.nvdcve.DatabaseProperties.MODIFIED;

 import org.owasp.dependencycheck.data.update.exception.InvalidDataException;

 import org.owasp.dependencycheck.data.update.exception.UpdateException;

 import org.owasp.dependencycheck.data.update.nvd.DownloadTask;

 import org.owasp.dependencycheck.data.update.nvd.NvdCveInfo;

 import org.owasp.dependencycheck.data.update.nvd.ProcessTask;

 import org.owasp.dependencycheck.data.update.nvd.UpdateableNvdCve;

 import org.owasp.dependencycheck.exception.NoDataException;

 import org.owasp.dependencycheck.utils.DateUtil;

 import org.owasp.dependencycheck.utils.DownloadFailedException;

 import org.owasp.dependencycheck.utils.InvalidSettingException;

 import org.owasp.dependencycheck.utils.Settings;

 import org.slf4j.Logger;

 import org.slf4j.LoggerFactory;

 /**

  * Class responsible for updating the NVD CVE data.

  *

  * @author Jeremy Long

  */

 public class NvdCveUpdater extends BaseUpdater implements CachedWebDataSource {

     /**

      * The logger

      */

     private static final Logger LOGGER = LoggerFactory.getLogger(NvdCveUpdater.class);

     /**

      * The max thread pool size to use when downloading files.

      */

     public static final int MAX_THREAD_POOL_SIZE = Settings.getInt(Settings.KEYS.MAX_DOWNLOAD_THREAD_POOL_SIZE, 3);

     /**

      * <p>

      * Downloads the latest NVD CVE XML file from the web and imports it into the current CVE Database.</p>

      *

      * @throws UpdateException is thrown if there is an error updating the database

      */

     @Override

     public void update() throws UpdateException {

         try {

             openDataStores();

             if (checkUpdate()) {

                 final UpdateableNvdCve updateable = getUpdatesNeeded();

                 if (updateable.isUpdateNeeded()) {

                     performUpdate(updateable);

                 }

             }

         } catch (MalformedURLException ex) {

             LOGGER.warn(

                     "NVD CVE properties files contain an invalid URL, unable to update the data to use the most current data.");

             LOGGER.debug("", ex);

         } catch (DownloadFailedException ex) {

             LOGGER.warn(

                     "Unable to download the NVD CVE data; the results may not include the most recent CPE/CVEs from the NVD.");

             if (Settings.getString(Settings.KEYS.PROXY_SERVER) == null) {

                 LOGGER.info(

                         "If you are behind a proxy you may need to configure dependency-check to use the proxy.");

             }

             LOGGER.debug("", ex);

         } finally {

             closeDataStores();

         }

     }

     /**

      * Checks if the NVD CVE XML files were last checked recently. As an optimization, we can avoid repetitive checks against the

      * NVD. Setting CVE_CHECK_VALID_FOR_HOURS determines the duration since last check before checking again. A database property

      * stores the timestamp of the last check.

      *

      * @return true to proceed with the check, or false to skip.

      * @throws UpdateException thrown when there is an issue checking for updates.

      */

     private boolean checkUpdate() throws UpdateException {

         boolean proceed = true;

         // If the valid setting has not been specified, then we proceed to check...

         final int validForHours = Settings.getInt(Settings.KEYS.CVE_CHECK_VALID_FOR_HOURS, 0);

         if (dataExists() && 0 < validForHours) {

             // ms Valid = valid (hours) x 60 min/hour x 60 sec/min x 1000 ms/sec

             final long msValid = validForHours * 60L * 60L * 1000L;

             final long lastChecked = Long.parseLong(getProperties().getProperty(DatabaseProperties.LAST_CHECKED, "0"));

             final long now = System.currentTimeMillis();

             proceed = (now - lastChecked) > msValid;

             if (proceed) {

                 getProperties().save(DatabaseProperties.LAST_CHECKED, Long.toString(now));

             } else {

                 LOGGER.info("Skipping NVD check since last check was within {} hours.", validForHours);

                 LOGGER.debug("Last NVD was at {}, and now {} is within {} ms.",

                         lastChecked, now, msValid);

             }

         }

         return proceed;

     }

     /**

      * Checks the CPE Index to ensure documents exists.

      */

     private boolean dataExists() {

         CveDB cve = null;

         try {

             cve = new CveDB();

             cve.open();

             return cve.dataExists();

         } catch (DatabaseException ex) {

             return false;

         } finally {

             if (cve != null) {

                 cve.close();

             }

         }

     }

     /**

      * Downloads the latest NVD CVE XML file from the web and imports it into the current CVE Database.

      *

      * @param updateable a collection of NVD CVE data file references that need to be downloaded and processed to update the

      * database

      * @throws UpdateException is thrown if there is an error updating the database

      */

     public void performUpdate(UpdateableNvdCve updateable) throws UpdateException {

         int maxUpdates = 0;

         try {

             for (NvdCveInfo cve : updateable) {

                 if (cve.getNeedsUpdate()) {

                     maxUpdates += 1;

                 }

             }

             if (maxUpdates <= 0) {

                 return;

             }

             if (maxUpdates > 3) {

                 LOGGER.info(

                         "NVD CVE requires several updates; this could take a couple of minutes.");

             }

             if (maxUpdates > 0) {

                 openDataStores();

             }

             final int poolSize = (MAX_THREAD_POOL_SIZE < maxUpdates) ? MAX_THREAD_POOL_SIZE : maxUpdates;

             final ExecutorService downloadExecutors = Executors.newFixedThreadPool(poolSize);

             final ExecutorService processExecutor = Executors.newSingleThreadExecutor();

             final Set<Future<Future<ProcessTask>>> downloadFutures = new HashSet<Future<Future<ProcessTask>>>(maxUpdates);

             for (NvdCveInfo cve : updateable) {

                 if (cve.getNeedsUpdate()) {

                     final DownloadTask call = new DownloadTask(cve, processExecutor, getCveDB(), Settings.getInstance());

                     downloadFutures.add(downloadExecutors.submit(call));

                 }

             }

             downloadExecutors.shutdown();

             //next, move the future future processTasks to just future processTasks

             final Set<Future<ProcessTask>> processFutures = new HashSet<Future<ProcessTask>>(maxUpdates);

             for (Future<Future<ProcessTask>> future : downloadFutures) {

                 Future<ProcessTask> task = null;

                 try {

                     task = future.get();

                 } catch (InterruptedException ex) {

                     downloadExecutors.shutdownNow();

                     processExecutor.shutdownNow();

                     LOGGER.debug("Thread was interrupted during download", ex);

                     throw new UpdateException("The download was interrupted", ex);

                 } catch (ExecutionException ex) {

                     downloadExecutors.shutdownNow();

                     processExecutor.shutdownNow();

                     LOGGER.debug("Thread was interrupted during download execution", ex);

                     throw new UpdateException("The execution of the download was interrupted", ex);

                 }

                 if (task == null) {

                     downloadExecutors.shutdownNow();

                     processExecutor.shutdownNow();

                     LOGGER.debug("Thread was interrupted during download");

                     throw new UpdateException("The download was interrupted; unable to complete the update");

                 } else {

                     processFutures.add(task);

                 }

             }

             for (Future<ProcessTask> future : processFutures) {

                 try {

                     final ProcessTask task = future.get();

                     if (task.getException() != null) {

                         throw task.getException();

                     }

                 } catch (InterruptedException ex) {

                     processExecutor.shutdownNow();

                     LOGGER.debug("Thread was interrupted during processing", ex);

                     throw new UpdateException(ex);

                 } catch (ExecutionException ex) {

                     processExecutor.shutdownNow();

                     LOGGER.debug("Execution Exception during process", ex);

                     throw new UpdateException(ex);

                 } finally {

                     processExecutor.shutdown();

                 }

             }

             if (maxUpdates >= 1) { //ensure the modified file date gets written (we may not have actually updated it)

                 getProperties().save(updateable.get(MODIFIED));

                 LOGGER.info("Begin database maintenance.");

                 getCveDB().cleanupDatabase();

                 LOGGER.info("End database maintenance.");

             }

         } finally {

             closeDataStores();

         }

     }

     /**

      * Determines if the index needs to be updated. This is done by fetching the NVD CVE meta data and checking the last update

      * date. If the data needs to be refreshed this method will return the NvdCveUrl for the files that need to be updated.

      *

      * @return the collection of files that need to be updated

      * @throws MalformedURLException is thrown if the URL for the NVD CVE Meta data is incorrect

      * @throws DownloadFailedException is thrown if there is an error. downloading the NVD CVE download data file

      * @throws UpdateException Is thrown if there is an issue with the last updated properties file

      */

     protected final UpdateableNvdCve getUpdatesNeeded() throws MalformedURLException, DownloadFailedException, UpdateException {

         UpdateableNvdCve updates = null;

         try {

             updates = retrieveCurrentTimestampsFromWeb();

         } catch (InvalidDataException ex) {

             final String msg = "Unable to retrieve valid timestamp from nvd cve downloads page";

             LOGGER.debug(msg, ex);

             throw new DownloadFailedException(msg, ex);

         } catch (InvalidSettingException ex) {

             LOGGER.debug("Invalid setting found when retrieving timestamps", ex);

             throw new DownloadFailedException("Invalid settings", ex);

         }

         if (updates == null) {

             throw new DownloadFailedException("Unable to retrieve the timestamps of the currently published NVD CVE data");

         }

         if (!getProperties().isEmpty()) {

             try {

                 final long lastUpdated = Long.parseLong(getProperties().getProperty(DatabaseProperties.LAST_UPDATED, "0"));

                 final long now = System.currentTimeMillis();

                 final int days = Settings.getInt(Settings.KEYS.CVE_MODIFIED_VALID_FOR_DAYS, 7);

                 if (lastUpdated == updates.getTimeStamp(MODIFIED)) {

                     updates.clear(); //we don't need to update anything.

                 } else if (DateUtil.withinDateRange(lastUpdated, now, days)) {

                     for (NvdCveInfo entry : updates) {

                         if (MODIFIED.equals(entry.getId())) {

                             entry.setNeedsUpdate(true);

                         } else {

                             entry.setNeedsUpdate(false);

                         }

                     }

                 } else { //we figure out which of the several XML files need to be downloaded.

                     for (NvdCveInfo entry : updates) {

                         if (MODIFIED.equals(entry.getId())) {

                             entry.setNeedsUpdate(true);

                         } else {

                             long currentTimestamp = 0;

                             try {

                                 currentTimestamp = Long.parseLong(getProperties().getProperty(DatabaseProperties.LAST_UPDATED_BASE

                                         + entry.getId(), "0"));

                             } catch (NumberFormatException ex) {

                                 LOGGER.debug("Error parsing '{}' '{}' from nvdcve.lastupdated",

                                         DatabaseProperties.LAST_UPDATED_BASE, entry.getId(), ex);

                             }

                             if (currentTimestamp == entry.getTimestamp()) {

                                 entry.setNeedsUpdate(false);

                             }

                         }

                     }

                 }

             } catch (NumberFormatException ex) {

                 LOGGER.warn("An invalid schema version or timestamp exists in the data.properties file.");

                 LOGGER.debug("", ex);

             }

         }

         return updates;

     }

     /**

      * Retrieves the timestamps from the NVD CVE meta data file.

      *

      * @return the timestamp from the currently published nvdcve downloads page

      * @throws MalformedURLException thrown if the URL for the NVD CCE Meta data is incorrect.

      * @throws DownloadFailedException thrown if there is an error downloading the nvd cve meta data file

      * @throws InvalidDataException thrown if there is an exception parsing the timestamps

      * @throws InvalidSettingException thrown if the settings are invalid

      */

     private UpdateableNvdCve retrieveCurrentTimestampsFromWeb()

             throws MalformedURLException, DownloadFailedException, InvalidDataException, InvalidSettingException {

         final UpdateableNvdCve updates = new UpdateableNvdCve();

         updates.add(MODIFIED, Settings.getString(Settings.KEYS.CVE_MODIFIED_20_URL),

                 Settings.getString(Settings.KEYS.CVE_MODIFIED_12_URL),

                 false);

         final int start = Settings.getInt(Settings.KEYS.CVE_START_YEAR);

         final int end = Calendar.getInstance().get(Calendar.YEAR);

         final String baseUrl20 = Settings.getString(Settings.KEYS.CVE_SCHEMA_2_0);

         final String baseUrl12 = Settings.getString(Settings.KEYS.CVE_SCHEMA_1_2);

         for (int i = start; i <= end; i++) {

             updates.add(Integer.toString(i), String.format(baseUrl20, i),

                     String.format(baseUrl12, i),

                     true);

         }

         return updates;

     }

 }