yacy_search_server/source/de/anomic/data/robotsParser.java

//robotsParser.java 
//-------------------------------------
//part of YACY
//(C) by Michael Peter Christen; mc@anomic.de
//first published on http://www.anomic.de
//Frankfurt, Germany, 2004
//
//This file ist contributed by Alexander Schier
//last major 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
//
//Using this software in any meaning (reading, learning, copying, compiling,
//running) means that you agree that the Author(s) is (are) not responsible
//for cost, loss of data or any harm that may be caused directly or indirectly
//by usage of this softare or this documentation. The usage of this software
//is on your own risk. The installation and usage (starting/running) of this
//software may allow other people or application to access your computer and
//any attached devices and is highly dependent on the configuration of the
//software which must be done by the user of the software; the author(s) is
//(are) also not responsible for proper configuration and usage of the
//software, even if provoked by documentation provided together with
//the software.
//
//Any changes to this file according to the GPL as documented in the file
//gpl.txt aside this file in the shipment you received can be done to the
//lines that follows this copyright notice here, but changes must not be
//done inside the copyright notive above. A re-distribution must contain
//the intact and unchanged copyright notice.
//Contributions and changes to the program code must be marked as such.

package de.anomic.data;

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLDecoder;
import java.util.ArrayList;
import java.util.Date;

import de.anomic.http.httpHeader;
import de.anomic.http.httpc;
import de.anomic.plasma.plasmaCrawlRobotsTxt;
import de.anomic.plasma.plasmaSwitchboard;
import de.anomic.server.logging.serverLog;

/*
 * A class for Parsing robots.txt files.
 * It only parses the Deny Part, yet.
 *  *
 * http://www.robotstxt.org/wc/norobots-rfc.html
 */
public final class robotsParser{
    
    /*public robotsParser(URL robotsUrl){
     }*/
    /*
     * this parses the robots.txt.
     * at the Moment it only creates a list of Deny Paths
     */
    
    public static ArrayList parse(File robotsFile) throws IOException {
        BufferedReader reader = null;
        try {
            reader = new BufferedReader(new FileReader(robotsFile));
            return parse(reader);
        } finally {
            if (reader != null) try{reader.close();}catch(Exception e){}
        }
    }
    
    public static ArrayList parse(byte[] robotsTxt) throws IOException {
        if ((robotsTxt == null)||(robotsTxt.length == 0)) return new ArrayList(0);
        ByteArrayInputStream bin = new ByteArrayInputStream(robotsTxt);
        BufferedReader reader = new BufferedReader(new InputStreamReader(bin));
        return parse(reader);
    }
    
    public static ArrayList parse(BufferedReader reader) throws IOException{
        ArrayList deny = new ArrayList();
        
        int pos;
        String line = null;
        boolean rule4Yacy = false;
        while ((line = reader.readLine()) != null) {
            line = line.trim();
            if (line.length() == 0) {
                // we have reached the end of the rule block
                rule4Yacy = false;
            } else if (line.startsWith("#")) {
                // we can ignore this. Just a comment line
            } else if ((!rule4Yacy) && (line.startsWith("User-agent:"))) {
                // cutting off comments at the line end
                pos = line.indexOf("#");
                if (pos != -1) {
                    line = line.substring(0,pos);
                }
                
                // getting out the robots name
                pos = line.indexOf(" ");
                if (pos != -1) {
                    String userAgent = line.substring(pos).trim();
                    rule4Yacy = (userAgent.equals("*") || (userAgent.toLowerCase().indexOf("yacy") >=0));
                }
            } else if (line.startsWith("Disallow:") && rule4Yacy) {
                pos = line.indexOf(" ");
                if (pos != -1) {
                    // getting the path
                    String path = line.substring(pos).trim();
                    
                    // unencoding all special charsx
                    path = URLDecoder.decode(path,"UTF-8");
                    
                    // escaping all occurences of ; because this char is used as special char in the Robots DB
                    path = path.replaceAll(";","%3B");                    
                    
                    // adding it to the pathlist
                    deny.add(path);
                }
            }
        }
        
        return deny;
    }
    
    public static boolean containsRobotsData(URL nexturl) {
        // generating the hostname:poart string needed to do a DB lookup
        String urlHostPort = nexturl.getHost() + ":" + ((nexturl.getPort()==-1)?80:nexturl.getPort());
        urlHostPort = urlHostPort.toLowerCase();
        
        // doing a DB lookup to determine if the robots data is already available
        plasmaCrawlRobotsTxt.Entry robotsTxt4Host = plasmaSwitchboard.robots.getEntry(urlHostPort);
        
        // if we have not found any data or the data is older than 7 days, we need to load it from the remote server
        if ((robotsTxt4Host == null) || (robotsTxt4Host.getLoadedDate() == null) ||
                (System.currentTimeMillis() - robotsTxt4Host.getLoadedDate().getTime() > 7*24*60*60*1000)) {
            return false;
        }
        return true;
    }
    
    
    public static boolean isDisallowed(URL nexturl) {
        if (nexturl == null) throw new IllegalArgumentException();               
        
        // generating the hostname:poart string needed to do a DB lookup
        String urlHostPort = nexturl.getHost() + ":" + ((nexturl.getPort()==-1)?80:nexturl.getPort());
        urlHostPort = urlHostPort.toLowerCase();
        
        // doing a DB lookup to determine if the robots data is already available
        plasmaCrawlRobotsTxt.Entry robotsTxt4Host = plasmaSwitchboard.robots.getEntry(urlHostPort);
        
        // if we have not found any data or the data is older than 7 days, we need to load it from the remote server
        if (
                (robotsTxt4Host == null) || 
                (robotsTxt4Host.getLoadedDate() == null) ||
                (System.currentTimeMillis() - robotsTxt4Host.getLoadedDate().getTime() > 7*24*60*60*1000)
           ) {
            URL robotsURL = null;
            // generating the proper url to download the robots txt
            try {                 
                robotsURL = new URL(nexturl.getProtocol(),nexturl.getHost(),(nexturl.getPort()==-1)?80:nexturl.getPort(),"/robots.txt");
            } catch (MalformedURLException e) {
                serverLog.logSevere("ROBOTS","Unable to generate robots.txt URL for URL '" + nexturl.toString() + "'.");
                return false;
            }
            
            Object[] result = null;
            boolean accessCompletelyRestricted = false;
            byte[] robotsTxt = null;
            String eTag = null;
            Date modDate = null;
            try { 
                serverLog.logFine("ROBOTS","Trying to download the robots.txt file from URL '" + robotsURL + "'.");
                result = downloadRobotsTxt(robotsURL,5,robotsTxt4Host);
                
                if (result != null) {
                    accessCompletelyRestricted = ((Boolean)result[0]).booleanValue();
                    robotsTxt = (byte[])result[1];
                    eTag = (String) result[2];
                    modDate = (Date) result[3];
                }                
            } catch (Exception e) {
                serverLog.logSevere("ROBOTS","Unable to download the robots.txt file from URL '" + robotsURL + "'. " + e.getMessage());
            }
            
            if ((robotsTxt4Host==null)||((robotsTxt4Host!=null)&&(result!=null))) {
                ArrayList denyPath = null;
                if (accessCompletelyRestricted) {
                    denyPath = new ArrayList();
                    denyPath.add("/");
                } else {
                    // parsing the robots.txt Data and converting it into an arraylist
                    try {
                        denyPath = robotsParser.parse(robotsTxt);
                    } catch (IOException e) {
                        serverLog.logSevere("ROBOTS","Unable to parse the robots.txt file from URL '" + robotsURL + "'.");
                    }
                } 
                
                // storing the data into the robots DB
                robotsTxt4Host = plasmaSwitchboard.robots.addEntry(urlHostPort,denyPath,new Date(),modDate,eTag);
            }
        }        
        
        if (robotsTxt4Host.isDisallowed(nexturl.getPath())) {
            return true;        
        }        
        return false;
    }
    
    private static Object[] downloadRobotsTxt(URL robotsURL, int redirectionCount, plasmaCrawlRobotsTxt.Entry entry) throws Exception {
        
        if (redirectionCount < 0) return new Object[]{Boolean.FALSE,null};
        redirectionCount--;
        
        boolean accessCompletelyRestricted = false;
        byte[] robotsTxt = null;
        httpc con = null;
        long downloadStart, downloadEnd;
        String eTag=null, oldEtag = null;
        Date lastMod=null;
        try {
            downloadStart = System.currentTimeMillis();
            plasmaSwitchboard sb = plasmaSwitchboard.getSwitchboard();
            if (!sb.remoteProxyUse) {
                con = httpc.getInstance(robotsURL.getHost(), robotsURL.getPort(), 10000, false);
            } else {
                con = httpc.getInstance(robotsURL.getHost(), robotsURL.getPort(), 10000, false, sb.remoteProxyHost, sb.remoteProxyPort);
            }
            
            // if we previously have downloaded this robots.txt then we can set the if-modified-since header
            httpHeader reqHeaders = new httpHeader();
            if (entry != null) {
                oldEtag = entry.getETag();
                reqHeaders = new httpHeader();
                Date modDate = entry.getModDate();
                if (modDate != null) reqHeaders.put(httpHeader.IF_MODIFIED_SINCE,entry.getModDate());
            }
            
            httpc.response res = con.GET(robotsURL.getPath(), reqHeaders);
            if (res.status.startsWith("2")) {
                if (!res.responseHeader.mime().startsWith("text/plain")) {
                    robotsTxt = null;
                    serverLog.logFinest("ROBOTS","Robots.txt from URL '" + robotsURL + "' has wrong mimetype '" + res.responseHeader.mime() + "'.");                    
                } else {

                    // getting some metadata
                    eTag = res.responseHeader.containsKey(httpHeader.ETAG)?((String)res.responseHeader.get(httpHeader.ETAG)).trim():null;
                    lastMod = res.responseHeader.lastModified();                    
                    
                    // if the robots.txt file was not changed we break here
                    if ((eTag != null) && (oldEtag != null) && (eTag.equals(oldEtag))) {
                        serverLog.logFinest("ROBOTS","Robots.txt from URL '" + robotsURL + "' was not modified. Abort downloading of new version.");
                        return null;
                    }
                    
                    // downloading the content
                    robotsTxt = res.writeContent();
                    con.close();
                    
                    downloadEnd = System.currentTimeMillis();                    
                    serverLog.logFinest("ROBOTS","Robots.txt successfully loaded from URL '" + robotsURL + "' in " + (downloadEnd-downloadStart) + " ms.");
                }
            } else if (res.status.startsWith("304")) {
                return null;
            } else if (res.status.startsWith("3")) {
                // getting redirection URL
                String redirectionUrlString = (String) res.responseHeader.get(httpHeader.LOCATION);
                redirectionUrlString = redirectionUrlString.trim();
                
                // generating the new URL object
                URL redirectionUrl = new URL(robotsURL, redirectionUrlString);
                
                // returning the used httpc
                httpc.returnInstance(con); 
                con = null;            
                
                // following the redirection
                serverLog.logFinest("ROBOTS","Redirection detected for robots.txt with URL '" + robotsURL + "'." + 
                        "\nRedirecting request to: " + redirectionUrl);
                return downloadRobotsTxt(redirectionUrl,redirectionCount,entry);
                
            } else if (res.status.startsWith("401") || res.status.startsWith("403")) {
                accessCompletelyRestricted = true;
                serverLog.logFinest("ROBOTS","Access to Robots.txt not allowed on URL '" + robotsURL + "'.");
            } else {
                serverLog.logFinest("ROBOTS","robots.txt could not be downloaded from URL '" + robotsURL + "'. [" + res.status + "].");
                robotsTxt = null;
            }        
        } catch (Exception e) {
            throw e;
        } finally {
            if (con != null) httpc.returnInstance(con);            
        }            
        return new Object[]{new Boolean(accessCompletelyRestricted),robotsTxt,eTag,lastMod};
    }
}