/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.
*/
package org.apache.nutch.protocol;
// JDK imports
import java.io.File;
import java.io.FileReader;
import java.io.LineNumberReader;
import java.net.URL;
import java.util.ArrayList;
import java.util.Hashtable;
import java.util.StringTokenizer;
// Commons Logging imports
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
// Nutch imports
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.conf.Configurable;
import org.apache.hadoop.io.Text;
import com.google.common.io.Files;
import crawlercommons.robots.BaseRobotRules;
import crawlercommons.robots.SimpleRobotRules;
import crawlercommons.robots.SimpleRobotRules.RobotRulesMode;
import crawlercommons.robots.SimpleRobotRulesParser;
/**
* This class uses crawler-commons for handling the parsing of {@code robots.txt} files.
* It emits SimpleRobotRules objects, which describe the download permissions
* as described in SimpleRobotRulesParser.
*/
public abstract class RobotRulesParser implements Configurable {
public static final Logger LOG = LoggerFactory.getLogger(RobotRulesParser.class);
protected static final Hashtable<String, BaseRobotRules> CACHE = new Hashtable<String, BaseRobotRules> ();
/**
* A {@link BaseRobotRules} object appropriate for use
* when the {@code robots.txt} file is empty or missing;
* all requests are allowed.
*/
public static final BaseRobotRules EMPTY_RULES = new SimpleRobotRules(RobotRulesMode.ALLOW_ALL);
/**
* A {@link BaseRobotRules} object appropriate for use when the
* {@code robots.txt} file is not fetched due to a {@code 403/Forbidden}
* response; all requests are disallowed.
*/
public static BaseRobotRules FORBID_ALL_RULES = new SimpleRobotRules(RobotRulesMode.ALLOW_NONE);
private static SimpleRobotRulesParser robotParser = new SimpleRobotRulesParser();
private Configuration conf;
protected String agentNames;
public RobotRulesParser() { }
public RobotRulesParser(Configuration conf) {
setConf(conf);
}
/**
* Set the {@link Configuration} object
*/
public void setConf(Configuration conf) {
this.conf = conf;
// Grab the agent names we advertise to robots files.
String agentName = conf.get("http.agent.name");
if (null == agentName) {
throw new RuntimeException("Agent name not configured!");
}
String agentNames = conf.get("http.robots.agents");
StringTokenizer tok = new StringTokenizer(agentNames, ",");
ArrayList<String> agents = new ArrayList<String>();
while (tok.hasMoreTokens()) {
agents.add(tok.nextToken().trim());
}
/**
* If there are no agents for robots-parsing, use the
* default agent-string. If both are present, our agent-string
* should be the first one we advertise to robots-parsing.
*/
if (agents.size() == 0) {
if (LOG.isErrorEnabled()) {
LOG.error("No agents listed in 'http.robots.agents' property!");
}
} else {
StringBuffer combinedAgentsString = new StringBuffer(agentName);
int index = 0;
if ((agents.get(0)).equalsIgnoreCase(agentName))
index++;
else if (LOG.isErrorEnabled()) {
LOG.error("Agent we advertise (" + agentName
+ ") not listed first in 'http.robots.agents' property!");
}
// append all the agents from the http.robots.agents property
for(; index < agents.size(); index++) {
combinedAgentsString.append(", " + agents.get(index));
}
// always make sure "*" is included in the end
combinedAgentsString.append(", *");
this.agentNames = combinedAgentsString.toString();
}
}
/**
* Get the {@link Configuration} object
*/
public Configuration getConf() {
return conf;
}
/**
* Parses the robots content using the {@link SimpleRobotRulesParser} from crawler commons
*
* @param url A string containing url
* @param content Contents of the robots file in a byte array
* @param contentType The
* @param robotName A string containing value of
* @return BaseRobotRules object
*/
public BaseRobotRules parseRules (String url, byte[] content, String contentType, String robotName) {
return robotParser.parseContent(url, content, contentType, robotName);
}
public BaseRobotRules getRobotRulesSet(Protocol protocol, String url) {
URL u = null;
try {
u = new URL(url);
} catch (Exception e) {
return EMPTY_RULES;
}
return getRobotRulesSet(protocol, u);
}
public abstract BaseRobotRules getRobotRulesSet(Protocol protocol, URL url);
/** command-line main for testing */
public static void main(String[] argv) {
if (argv.length < 3) {
System.err.println("Usage: RobotRulesParser <robots-file> <url-file> <agent-names>\n");
System.err.println(" <robots-file> - Input robots.txt file which will be parsed.");
System.err.println(" <url-file> - Contains input URLs (1 per line) which are tested against the rules.");
System.err.println(" <agent-names> - Input agent name. Multiple agent names can be specified using spaces.");
System.exit(-1);
}
try {
StringBuilder agentNames = new StringBuilder();
for(int counter = 2; counter < argv.length; counter++)
agentNames.append(argv[counter]).append(",");
agentNames.deleteCharAt(agentNames.length()-1);
byte[] robotsBytes = Files.toByteArray(new File(argv[0]));
BaseRobotRules rules = robotParser.parseContent(argv[0], robotsBytes, "text/plain", agentNames.toString());
LineNumberReader testsIn = new LineNumberReader(new FileReader(argv[1]));
String testPath = testsIn.readLine().trim();
while (testPath != null) {
System.out.println( (rules.isAllowed(testPath) ? "allowed" : "not allowed") +
":\t" + testPath);
testPath = testsIn.readLine();
}
testsIn.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}