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318 lines
12 KiB
318 lines
12 KiB
/*
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robotsParser.java
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-------------------------------------
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part of YACY
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(C) 2005, 2006 by Alexander Schier
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Martin Thelian
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last change: $LastChangedDate$LastChangedBy: orbiter $
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Revision: $LastChangedRevision$
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General public License for more details.
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You should have received a copy of the GNU General private License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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extended to return structured objects instead of a Object[] and
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extended to return a Allow-List by Michael Christen, 21.07.2008
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extended to allow multiple user agents given by definition and
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returning the used user agent my Michael Christen 3.4.2011
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*/
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package de.anomic.crawler;
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import java.io.BufferedReader;
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import java.io.ByteArrayInputStream;
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import java.io.IOException;
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import java.io.InputStreamReader;
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import java.net.MalformedURLException;
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import java.util.ArrayList;
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import java.util.HashSet;
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import java.util.Set;
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import java.util.regex.Pattern;
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import net.yacy.cora.document.MultiProtocolURI;
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import net.yacy.cora.document.UTF8;
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import net.yacy.kelondro.data.meta.DigestURI;
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/*
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* A class for Parsing robots.txt files.
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* It only parses the Deny Part, yet.
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*
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* Robots RFC
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* http://www.robotstxt.org/wc/norobots-rfc.html
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*
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* TODO:
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* - On the request attempt resulted in temporary failure a robot
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* should defer visits to the site until such time as the resource
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* can be retrieved.
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*
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* - Extended Standard for Robot Exclusion
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* See: http://www.conman.org/people/spc/robots2.html
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*
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* - Robot Exclusion Standard Revisited
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* See: http://www.kollar.com/robots.html
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*/
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public final class RobotsTxtParser {
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private static final Pattern patternTab = Pattern.compile("\t");
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private static final String ROBOTS_USER_AGENT = "User-agent:".toUpperCase();
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private static final String ROBOTS_DISALLOW = "Disallow:".toUpperCase();
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private static final String ROBOTS_ALLOW = "Allow:".toUpperCase();
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private static final String ROBOTS_COMMENT = "#";
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private static final String ROBOTS_SITEMAP = "Sitemap:".toUpperCase();
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private static final String ROBOTS_CRAWL_DELAY = "Crawl-delay:".toUpperCase();
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private final ArrayList<String> allowList;
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private final ArrayList<String> denyList;
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private String sitemap;
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private long crawlDelayMillis;
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private final Set<String> myNames; // a list of own name lists
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private String agentName; // the name of the agent that was used to return the result
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protected RobotsTxtParser(final Set<String> myNames) {
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this.allowList = new ArrayList<String>(0);
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this.denyList = new ArrayList<String>(0);
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this.sitemap = "";
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this.crawlDelayMillis = 0;
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this.myNames = myNames;
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this.agentName = null;
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}
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protected RobotsTxtParser(final Set<String> myNames, final byte[] robotsTxt) {
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this(myNames);
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if (robotsTxt != null && robotsTxt.length != 0) {
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final ByteArrayInputStream bin = new ByteArrayInputStream(robotsTxt);
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final BufferedReader reader = new BufferedReader(new InputStreamReader(bin));
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parse(reader);
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}
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}
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public static RobotsTxtParser getRobots(String homepage) {
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DigestURI theURL;
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try {
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theURL = new DigestURI(homepage);
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} catch (MalformedURLException e1) {
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return null;
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}
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final String urlHostPort = RobotsTxt.getHostPort(theURL);
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MultiProtocolURI robotsURL = null;
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try {
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robotsURL = new MultiProtocolURI("http://" + urlHostPort + "/robots.txt");
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} catch (final MalformedURLException e) {
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return null;
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}
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Object[] result;
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try {
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result = RobotsTxt.downloadRobotsTxt(robotsURL, 0, null);
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} catch (Exception e) {
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return null;
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}
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final byte[] robotsTxt = (byte[]) result[RobotsTxt.DOWNLOAD_ROBOTS_TXT];
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RobotsTxtParser parserResult = new RobotsTxtParser(new HashSet<String>(), robotsTxt);
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return parserResult;
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}
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private void parse(final BufferedReader reader) {
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final ArrayList<String> deny4AllAgents = new ArrayList<String>();
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final ArrayList<String> deny4ThisAgents = new ArrayList<String>();
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final ArrayList<String> allow4AllAgents = new ArrayList<String>();
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final ArrayList<String> allow4ThisAgents = new ArrayList<String>();
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int pos;
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String line = null, lineUpper = null;
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boolean isRule4AllAgents = false,
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isRule4ThisAgents = false,
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rule4ThisAgentsFound = false,
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inBlock = false;
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try {
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lineparser: while ((line = reader.readLine()) != null) {
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// replacing all tabs with spaces
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line = patternTab.matcher(line).replaceAll(" ").trim();
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lineUpper = line.toUpperCase();
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// parse empty line
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if (line.isEmpty()) {
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// we have reached the end of the rule block
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if (rule4ThisAgentsFound) {
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// stop here because other robot blocks are either not for YaCy
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// or global settings which shall not overwrite YaCys settings.
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break lineparser;
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}
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continue lineparser;
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}
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// parse comment
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if (line.startsWith(ROBOTS_COMMENT)) {
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// we can ignore this. Just a comment line
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continue lineparser;
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}
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// parse sitemap; if there are several sitemaps then take the first url
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// TODO: support for multiple sitemaps
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if (lineUpper.startsWith(ROBOTS_SITEMAP) && (this.sitemap == null || this.sitemap.isEmpty())) {
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pos = line.indexOf(' ');
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if (pos != -1) {
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this.sitemap = line.substring(pos).trim();
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}
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continue lineparser;
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}
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// parse user agent
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if (lineUpper.startsWith(ROBOTS_USER_AGENT)) {
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if (inBlock) {
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// we have detected the start of a new block
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if (rule4ThisAgentsFound) {
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// stop here because other robot blocks are either not for YaCy
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// or global settings which shall not overwrite YaCys settings.
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break lineparser;
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}
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inBlock = false;
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isRule4AllAgents = false;
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isRule4ThisAgents = false;
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this.crawlDelayMillis = 0; // each block has a separate delay
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}
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// cutting off comments at the line end
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pos = line.indexOf(ROBOTS_COMMENT);
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if (pos != -1) line = line.substring(0,pos).trim();
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// getting out the robots name
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pos = line.indexOf(' ');
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if (pos != -1) {
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final String userAgent = line.substring(pos).trim();
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isRule4AllAgents |= userAgent.equals("*");
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for (final String agent: this.myNames) {
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if (userAgent.toLowerCase().equals(agent)) {
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this.agentName = agent;
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isRule4ThisAgents = true;
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break;
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}
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}
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if (isRule4ThisAgents) rule4ThisAgentsFound = true;
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}
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continue lineparser;
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}
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// parse crawl delay
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if (lineUpper.startsWith(ROBOTS_CRAWL_DELAY)) {
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inBlock = true;
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if (isRule4ThisAgents || isRule4AllAgents) {
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pos = line.indexOf(' ');
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if (pos != -1) {
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try {
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// the crawl delay can be a float number and means number of seconds
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this.crawlDelayMillis = (long) (1000.0 * Float.parseFloat(line.substring(pos).trim()));
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} catch (final NumberFormatException e) {
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// invalid crawling delay
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}
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}
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}
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continue lineparser;
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}
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// parse disallow
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if (lineUpper.startsWith(ROBOTS_DISALLOW) || lineUpper.startsWith(ROBOTS_ALLOW)) {
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inBlock = true;
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final boolean isDisallowRule = lineUpper.startsWith(ROBOTS_DISALLOW);
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if (isRule4ThisAgents || isRule4AllAgents) {
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// cutting off comments at the line end
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pos = line.indexOf(ROBOTS_COMMENT);
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if (pos != -1) line = line.substring(0,pos).trim();
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// cut off tailing *
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if (line.endsWith("*")) line = line.substring(0,line.length()-1);
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// parse the path
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pos = line.indexOf(' ');
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if (pos >= 0) {
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// getting the path
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String path = line.substring(pos).trim();
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// unencoding all special charsx
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try {
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path = UTF8.decodeURL(path);
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} catch (final Exception e) {
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/*
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* url decoding failed. E.g. because of
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* "Incomplete trailing escape (%) pattern"
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*/
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}
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// escaping all occurences of ; because this char is used as special char in the Robots DB
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path = RobotsTxt.ROBOTS_DB_PATH_SEPARATOR_MATCHER.matcher(path).replaceAll("%3B");
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// adding it to the pathlist
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if (isDisallowRule) {
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if (isRule4AllAgents) deny4AllAgents.add(path);
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if (isRule4ThisAgents) deny4ThisAgents.add(path);
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} else {
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if (isRule4AllAgents) allow4AllAgents.add(path);
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if (isRule4ThisAgents) allow4ThisAgents.add(path);
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}
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}
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}
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continue lineparser;
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}
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}
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} catch (final IOException e) {}
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this.allowList.addAll(rule4ThisAgentsFound ? allow4ThisAgents : allow4AllAgents);
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this.denyList.addAll(rule4ThisAgentsFound ? deny4ThisAgents : deny4AllAgents);
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}
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/**
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* a crawl delay can be assigned to every agent or for all agents
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* a special case is where the user agent of this yacy peer is given explicitely
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* using the peer name and then if the crawl delay is given as '0' the crawler
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* does not make any no-DOS-forced crawl pause.
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* @return the crawl delay between two crawl access times in milliseconds
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*/
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protected long crawlDelayMillis() {
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return this.crawlDelayMillis;
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}
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/**
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* the user agent that was applied to get the crawl properties is recorded
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* because it is possible that this robots.txt parser applies to several user agents
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* which may be i.e. 'yacy', 'yacybot', <peer-name>'.yacy' or <peer-hash>'.yacyh'
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* Effects: see also comment to crawlDelayMillis()
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* @return the name of the user agent that was used for the result properties or null if no user agent name was used to identify the agent
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*/
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protected String agentName() {
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return this.agentName;
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}
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protected String sitemap() {
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return this.sitemap;
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}
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protected ArrayList<String> allowList() {
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return this.allowList;
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}
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protected ArrayList<String> denyList() {
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return this.denyList;
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}
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}
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