//plasmaCrawlRobotsTxt.java
//-------------------------------------
//part of YACY
//(C) by Michael Peter Christen; mc@yacy.net
//first published on http://www.anomic.de
//Frankfurt, Germany, 2004
//
//This file is contributed by Martin Thelian
// [MC] moved some methods from robotsParser file that had been created by Alexander Schier to this class
//last major change: $LastChangedDate: 2011-05-26 12:57:02 +0200 (Do, 26. Mai 2011) $ by $LastChangedBy: orbiter $
//Revision: $LastChangedRevision: 7738 $
//
//This program is free software; you can redistribute it and/or modify
//it under the terms of the GNU General public License as published by
//the Free Software Foundation; either version 2 of the License, or
//(at your option) any later version.
//
//This program is distributed in the hope that it will be useful,
//but WITHOUT ANY WARRANTY; without even the implied warranty of
//MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
//GNU General public License for more details.
//
//You should have received a copy of the GNU General public License
//along with this program; if not, write to the Free Software
//Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
package de.anomic.crawler;
import java.io.IOException;
import java.net.MalformedURLException;
import java.util.ArrayList;
import java.util.Date;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.regex.Pattern;
import org.apache.log4j.Logger;
import net.yacy.cora.document.MultiProtocolURI;
import net.yacy.cora.protocol.ClientIdentification;
import net.yacy.cora.protocol.HeaderFramework;
import net.yacy.cora.protocol.RequestHeader;
import net.yacy.cora.protocol.ResponseHeader;
import net.yacy.cora.protocol.http.HTTPClient;
import net.yacy.kelondro.blob.BEncodedHeap;
import net.yacy.kelondro.index.RowSpaceExceededException;
import net.yacy.kelondro.io.ByteCount;
public class RobotsTxt {
private static Logger log = Logger.getLogger(RobotsTxt.class);
protected static final String ROBOTS_DB_PATH_SEPARATOR = ";";
protected static final Pattern ROBOTS_DB_PATH_SEPARATOR_MATCHER = Pattern.compile(ROBOTS_DB_PATH_SEPARATOR);
BEncodedHeap robotsTable;
private final ConcurrentHashMap<String, DomSync> syncObjects;
//private static final HashSet<String> loadedRobots = new HashSet<String>(); // only for debugging
private static class DomSync {
private DomSync() {}
}
public RobotsTxt(final BEncodedHeap robotsTable) {
this.robotsTable = robotsTable;
syncObjects = new ConcurrentHashMap<String, DomSync>();
log.info("initiated robots table: " + robotsTable.getFile());
}
public void clear() {
log.info("clearing robots table");
this.robotsTable.clear();
syncObjects.clear();
}
public int size() {
return this.robotsTable.size();
}
public RobotsTxtEntry getEntry(final MultiProtocolURI theURL, final Set<String> thisAgents) throws IOException {
if (theURL == null) throw new IllegalArgumentException();
if (!theURL.getProtocol().startsWith("http")) return null;
return getEntry(theURL, thisAgents, true);
}
private RobotsTxtEntry getEntry(final MultiProtocolURI theURL, final Set<String> thisAgents, final boolean fetchOnlineIfNotAvailableOrNotFresh) throws IOException {
// this method will always return a non-null value
String urlHostPort = getHostPort(theURL);
RobotsTxtEntry robotsTxt4Host = null;
Map<String, byte[]> record;
try {
record = this.robotsTable.get(this.robotsTable.encodedKey(urlHostPort));
} catch (RowSpaceExceededException e) {
log.warn("memory exhausted", e);
record = null;
}
if (record != null) robotsTxt4Host = new RobotsTxtEntry(urlHostPort, record);
if (fetchOnlineIfNotAvailableOrNotFresh && (
robotsTxt4Host == null ||
robotsTxt4Host.getLoadedDate() == null ||
System.currentTimeMillis() - robotsTxt4Host.getLoadedDate().getTime() > 7*24*60*60*1000
)) {
// make or get a synchronization object
DomSync syncObj = this.syncObjects.get(urlHostPort);
if (syncObj == null) {
syncObj = new DomSync();
this.syncObjects.put(urlHostPort, syncObj);
}
// we can now synchronize for each host separately
synchronized (syncObj) {
// if we have not found any data or the data is older than 7 days, we need to load it from the remote server
// check the robots table again for all threads that come here because they waited for another one
// to complete a download
try {
record = this.robotsTable.get(this.robotsTable.encodedKey(urlHostPort));
} catch (RowSpaceExceededException e) {
log.warn("memory exhausted", e);
record = null;
}
if (record != null) robotsTxt4Host = new RobotsTxtEntry(urlHostPort, record);
if (robotsTxt4Host != null &&
robotsTxt4Host.getLoadedDate() != null &&
System.currentTimeMillis() - robotsTxt4Host.getLoadedDate().getTime() <= 1*24*60*60*1000) {
return robotsTxt4Host;
}
// generating the proper url to download the robots txt
MultiProtocolURI robotsURL = null;
try {
robotsURL = new MultiProtocolURI("http://" + urlHostPort + "/robots.txt");
} catch (final MalformedURLException e) {
log.fatal("Unable to generate robots.txt URL for host:port '" + urlHostPort + "'.", e);
robotsURL = null;
}
Object[] result = null;
if (robotsURL != null) {
if (log.isDebugEnabled()) log.debug("Trying to download the robots.txt file from URL '" + robotsURL + "'.");
try {
result = downloadRobotsTxt(robotsURL, 3, robotsTxt4Host);
} catch (final Exception e) {
result = null;
}
}
/*
assert !loadedRobots.contains(robotsURL.toNormalform(false, false)) :
"robots-url=" + robotsURL.toString() +
", robots=" + ((result == null || result[DOWNLOAD_ROBOTS_TXT] == null) ? "NULL" : UTF8.String((byte[]) result[DOWNLOAD_ROBOTS_TXT])) +
", robotsTxt4Host=" + ((robotsTxt4Host == null) ? "NULL" : robotsTxt4Host.getLoadedDate().toString());
loadedRobots.add(robotsURL.toNormalform(false, false));
*/
if (result == null) {
// no robots.txt available, make an entry to prevent that the robots loading is done twice
if (robotsTxt4Host == null) {
// generate artificial entry
robotsTxt4Host = new RobotsTxtEntry(
robotsURL,
new ArrayList<String>(),
new ArrayList<String>(),
new Date(),
new Date(),
null,
null,
Integer.valueOf(0),
null);
} else {
robotsTxt4Host.setLoadedDate(new Date());
}
// store the data into the robots DB
int sz = this.robotsTable.size();
addEntry(robotsTxt4Host);
if (this.robotsTable.size() <= sz) {
log.fatal("new entry in robots.txt table failed, resetting database");
this.clear();
addEntry(robotsTxt4Host);
}
} else {
final RobotsTxtParser parserResult = new RobotsTxtParser((byte[]) result[DOWNLOAD_ROBOTS_TXT], thisAgents);
ArrayList<String> denyPath = parserResult.denyList();
if (((Boolean) result[DOWNLOAD_ACCESS_RESTRICTED]).booleanValue()) {
denyPath = new ArrayList<String>();
denyPath.add("/");
}
// store the data into the robots DB
robotsTxt4Host = addEntry(
robotsURL,
parserResult.allowList(),
denyPath,
new Date(),
(Date) result[DOWNLOAD_MODDATE],
(String) result[DOWNLOAD_ETAG],
parserResult.sitemap(),
parserResult.crawlDelayMillis(),
parserResult.agentName());
}
}
}
return robotsTxt4Host;
}
private RobotsTxtEntry addEntry(
final MultiProtocolURI theURL,
final ArrayList<String> allowPathList,
final ArrayList<String> denyPathList,
final Date loadedDate,
final Date modDate,
final String eTag,
final String sitemap,
final long crawlDelayMillis,
final String agentName
) {
final RobotsTxtEntry entry = new RobotsTxtEntry(
theURL, allowPathList, denyPathList,
loadedDate, modDate,
eTag, sitemap, crawlDelayMillis, agentName);
addEntry(entry);
return entry;
}
private String addEntry(final RobotsTxtEntry entry) {
// writes a new page and returns key
try {
this.robotsTable.insert(this.robotsTable.encodedKey(entry.getHostName()), entry.getMem());
return entry.getHostName();
} catch (final Exception e) {
log.warn("cannot write robots.txt entry", e);
return null;
}
}
// methods that had been in robotsParser.java:
private static final int DOWNLOAD_ACCESS_RESTRICTED = 0;
private static final int DOWNLOAD_ROBOTS_TXT = 1;
private static final int DOWNLOAD_ETAG = 2;
private static final int DOWNLOAD_MODDATE = 3;
static final String getHostPort(final MultiProtocolURI theURL) {
String urlHostPort = null;
final int port = getPort(theURL);
urlHostPort = theURL.getHost() + ":" + port;
urlHostPort = urlHostPort.toLowerCase().intern();
return urlHostPort;
}
private static final int getPort(final MultiProtocolURI theURL) {
int port = theURL.getPort();
if (port == -1) {
if (theURL.getProtocol().equalsIgnoreCase("http")) {
port = 80;
} else if (theURL.getProtocol().equalsIgnoreCase("https")) {
port = 443;
}
}
return port;
}
private static Object[] downloadRobotsTxt(final MultiProtocolURI robotsURL, int redirectionCount, final RobotsTxtEntry entry) throws Exception {
if (robotsURL == null || !robotsURL.getProtocol().startsWith("http")) return null;
if (redirectionCount < 0) return new Object[]{Boolean.FALSE,null,null};
redirectionCount--;
boolean accessCompletelyRestricted = false;
byte[] robotsTxt = null;
long downloadStart, downloadEnd;
String eTag=null, oldEtag = null;
Date lastMod=null;
downloadStart = System.currentTimeMillis();
// if we previously have downloaded this robots.txt then we can set the if-modified-since header
RequestHeader reqHeaders = new RequestHeader();
// add yacybot user agent
reqHeaders.put(HeaderFramework.USER_AGENT, ClientIdentification.getUserAgent());
// adding referer
reqHeaders.put(RequestHeader.REFERER, (MultiProtocolURI.newURL(robotsURL,"/")).toNormalform(true, true));
if (entry != null) {
oldEtag = entry.getETag();
reqHeaders = new RequestHeader();
final Date modDate = entry.getModDate();
if (modDate != null) reqHeaders.put(RequestHeader.IF_MODIFIED_SINCE, HeaderFramework.formatRFC1123(entry.getModDate()));
}
// setup http-client
//TODO: adding Traffic statistic for robots download?
final HTTPClient client = new HTTPClient();
client.setHeader(reqHeaders.entrySet());
try {
// check for interruption
if (Thread.currentThread().isInterrupted()) throw new InterruptedException("Shutdown in progress.");
// sending the get request
robotsTxt = client.GETbytes(robotsURL);
// statistics:
if (robotsTxt != null) {
ByteCount.addAccountCount(ByteCount.CRAWLER, robotsTxt.length);
}
final int code = client.getHttpResponse().getStatusLine().getStatusCode();
final ResponseHeader header = new ResponseHeader(client.getHttpResponse().getAllHeaders());
// check the response status
if (code > 199 && code < 300) {
if (!header.mime().startsWith("text/plain")) {
robotsTxt = null;
log.info("Robots.txt from URL '" + robotsURL + "' has wrong mimetype '" + header.mime() + "'.");
} else {
// getting some metadata
eTag = header.containsKey(HeaderFramework.ETAG)?(header.get(HeaderFramework.ETAG)).trim():null;
lastMod = header.lastModified();
// if the robots.txt file was not changed we break here
if ((eTag != null) && (oldEtag != null) && (eTag.equals(oldEtag))) {
if (log.isDebugEnabled()) log.debug("Robots.txt from URL '" + robotsURL + "' was not modified. Abort downloading of new version.");
return null;
}
downloadEnd = System.currentTimeMillis();
if (log.isDebugEnabled()) log.debug("Robots.txt successfully loaded from URL '" + robotsURL + "' in " + (downloadEnd-downloadStart) + " ms.");
}
} else if (code == 304) {
return null;
} else if (code > 299 && code < 400) {
// getting redirection URL
String redirectionUrlString = header.get(HeaderFramework.LOCATION);
if (redirectionUrlString==null) {
if (log.isDebugEnabled())
log.debug("robots.txt could not be downloaded from URL '" + robotsURL + "' because of missing redirecton header. [" + client.getHttpResponse().getStatusLine() + "].");
robotsTxt = null;
} else {
redirectionUrlString = redirectionUrlString.trim();
// generating the new URL object
final MultiProtocolURI redirectionUrl = MultiProtocolURI.newURL(robotsURL, redirectionUrlString);
// following the redirection
if (log.isDebugEnabled()) log.debug("Redirection detected for robots.txt with URL '" + robotsURL + "'." +
"\nRedirecting request to: " + redirectionUrl);
return downloadRobotsTxt(redirectionUrl,redirectionCount,entry);
}
} else if (code == 401 || code == 403) {
accessCompletelyRestricted = true;
if (log.isDebugEnabled()) log.debug("Access to Robots.txt not allowed on URL '" + robotsURL + "'.");
} else {
if (log.isDebugEnabled())
log.debug("robots.txt could not be downloaded from URL '" + robotsURL + "'. [" + client.getHttpResponse().getStatusLine() + "].");
robotsTxt = null;
}
} catch (final Exception e) {
throw e;
}
return new Object[]{Boolean.valueOf(accessCompletelyRestricted),robotsTxt,eTag,lastMod};
}
}