//robotsParser.java
//-------------------------------------
//part of YACY
//
//(C) 2005, 2006 by Alexander Schier
// Martin Thelian
//
//last change: $LastChangedDate$ by $LastChangedBy$
//Revision: $LastChangedRevision$
//
//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
// extended to return structured objects instead of a Object[] and
// extended to return a Allow-List by Michael Christen, 21.07.2008
package de.anomic.crawler;
import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URLDecoder;
import java.util.ArrayList;
/*
* A class for Parsing robots.txt files.
* It only parses the Deny Part, yet.
*
* Robots RFC
* http://www.robotstxt.org/wc/norobots-rfc.html
*
* TODO:
* - On the request attempt resulted in temporary failure a robot
* should defer visits to the site until such time as the resource
* can be retrieved.
*
* - Extended Standard for Robot Exclusion
* See: http://www.conman.org/people/spc/robots2.html
*
* - Robot Exclusion Standard Revisited
* See: http://www.kollar.com/robots.html
*/
public final class robotsParser {
public static final String ROBOTS_USER_AGENT = "User-agent:".toUpperCase();
public static final String ROBOTS_DISALLOW = "Disallow:".toUpperCase();
public static final String ROBOTS_ALLOW = "Allow:".toUpperCase();
public static final String ROBOTS_COMMENT = "#";
public static final String ROBOTS_SITEMAP = "Sitemap:".toUpperCase();
public static final String ROBOTS_CRAWL_DELAY = "Crawl-Delay:".toUpperCase();
private ArrayList<String> allowList;
private ArrayList<String> denyList;
private String sitemap;
private long crawlDelayMillis;
public robotsParser(final byte[] robotsTxt) {
if ((robotsTxt == null)||(robotsTxt.length == 0)) {
allowList = new ArrayList<String>(0);
denyList = new ArrayList<String>(0);
sitemap = "";
crawlDelayMillis = 0;
} else {
final ByteArrayInputStream bin = new ByteArrayInputStream(robotsTxt);
final BufferedReader reader = new BufferedReader(new InputStreamReader(bin));
parse(reader);
}
}
public robotsParser(final BufferedReader reader) {
if (reader == null) {
allowList = new ArrayList<String>(0);
denyList = new ArrayList<String>(0);
sitemap = "";
crawlDelayMillis = 0;
} else {
parse(reader);
}
}
private void parse(final BufferedReader reader) {
final ArrayList<String> deny4AllAgents = new ArrayList<String>();
final ArrayList<String> deny4YaCyAgent = new ArrayList<String>();
final ArrayList<String> allow4AllAgents = new ArrayList<String>();
final ArrayList<String> allow4YaCyAgent = new ArrayList<String>();
int pos;
String line = null, lineUpper = null;
sitemap = null;
crawlDelayMillis = 0;
boolean isRule4AllAgents = false,
isRule4YaCyAgent = false,
rule4YaCyFound = false,
inBlock = false;
try {
while ((line = reader.readLine()) != null) {
// replacing all tabs with spaces
line = line.replaceAll("\t"," ").trim();
lineUpper = line.toUpperCase();
if (line.length() == 0) {
// OLD: we have reached the end of the rule block
// rule4Yacy = false; inBlock = false;
// NEW: just ignore it
} else if (line.startsWith(ROBOTS_COMMENT)) {
// we can ignore this. Just a comment line
} else if (lineUpper.startsWith(ROBOTS_SITEMAP)) {
pos = line.indexOf(" ");
if (pos != -1) {
sitemap = line.substring(pos).trim();
}
} else if (lineUpper.startsWith(ROBOTS_USER_AGENT)) {
if (inBlock) {
// we have detected the start of a new block
inBlock = false;
isRule4AllAgents = false;
isRule4YaCyAgent = false;
crawlDelayMillis = 0; // each block has a separate delay
}
// cutting off comments at the line end
pos = line.indexOf(ROBOTS_COMMENT);
if (pos != -1) line = line.substring(0,pos).trim();
// getting out the robots name
pos = line.indexOf(" ");
if (pos != -1) {
final String userAgent = line.substring(pos).trim();
isRule4AllAgents |= userAgent.equals("*");
isRule4YaCyAgent |= userAgent.toLowerCase().indexOf("yacy") >=0;
if (isRule4YaCyAgent) rule4YaCyFound = true;
}
} else if (lineUpper.startsWith(ROBOTS_CRAWL_DELAY)) {
inBlock = true;
if (isRule4YaCyAgent || isRule4AllAgents) {
pos = line.indexOf(" ");
if (pos != -1) {
try {
// the crawl delay can be a float number and means number of seconds
crawlDelayMillis = (long) (1000.0 * Float.parseFloat(line.substring(pos).trim()));
} catch (final NumberFormatException e) {
// invalid crawling delay
}
}
}
} else if (lineUpper.startsWith(ROBOTS_DISALLOW) ||
lineUpper.startsWith(ROBOTS_ALLOW)) {
inBlock = true;
final boolean isDisallowRule = lineUpper.startsWith(ROBOTS_DISALLOW);
if (isRule4YaCyAgent || isRule4AllAgents) {
// cutting off comments at the line end
pos = line.indexOf(ROBOTS_COMMENT);
if (pos != -1) line = line.substring(0,pos).trim();
// cutting of tailing *
if (line.endsWith("*")) line = line.substring(0,line.length()-1);
// getting the path
pos = line.indexOf(" ");
if (pos != -1) {
// getting the path
String path = line.substring(pos).trim();
// unencoding all special charsx
try {
path = URLDecoder.decode(path,"UTF-8");
} catch (final Exception e) {
/*
* url decoding failed. E.g. because of
* "Incomplete trailing escape (%) pattern"
*/
}
// escaping all occurences of ; because this char is used as special char in the Robots DB
path = path.replaceAll(RobotsTxt.ROBOTS_DB_PATH_SEPARATOR,"%3B");
// adding it to the pathlist
if (isDisallowRule) {
if (isRule4AllAgents) deny4AllAgents.add(path);
if (isRule4YaCyAgent) deny4YaCyAgent.add(path);
} else {
if (isRule4AllAgents) allow4AllAgents.add(path);
if (isRule4YaCyAgent) allow4YaCyAgent.add(path);
}
}
}
}
}
} catch (final IOException e) {}
allowList = (rule4YaCyFound) ? allow4YaCyAgent : allow4AllAgents;
denyList = (rule4YaCyFound) ? deny4YaCyAgent : deny4AllAgents;
}
public long crawlDelayMillis() {
return this.crawlDelayMillis;
}
public String sitemap() {
return this.sitemap;
}
public ArrayList<String> allowList() {
return this.allowList;
}
public ArrayList<String> denyList() {
return this.denyList;
}
}