Author: markt
Date: Sun Feb 6 19:28:48 2011
New Revision: 1067734
URL: http://svn.apache.org/viewvc?rev=1067734&view=rev
Log:
First attempt at a valve to limit session creation by web crawlers.
Docs etc to follow once it is confirmed working.
Added:
tomcat/trunk/java/org/apache/catalina/valves/CrawlerSessionManagerValve.java
(with props)
Added:
tomcat/trunk/java/org/apache/catalina/valves/CrawlerSessionManagerValve.java
URL:
http://svn.apache.org/viewvc/tomcat/trunk/java/org/apache/catalina/valves/CrawlerSessionManagerValve.java?rev=1067734&view=auto
==============================================================================
---
tomcat/trunk/java/org/apache/catalina/valves/CrawlerSessionManagerValve.java
(added)
+++
tomcat/trunk/java/org/apache/catalina/valves/CrawlerSessionManagerValve.java
Sun Feb 6 19:28:48 2011
@@ -0,0 +1,195 @@
+/*
+ * 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.catalina.valves;
+
+import java.io.IOException;
+import java.util.Enumeration;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpSession;
+
+import org.apache.catalina.LifecycleException;
+import org.apache.catalina.connector.Request;
+import org.apache.catalina.connector.Response;
+
+/**
+ * Web crawlers can trigger the creation of many thousands of sessions as they
+ * crawl a site which may result in significant memory consumption. This Valve
+ * ensures that crawlers are associated with a single session - just like
normal
+ * users - regardless of whether or not they provide a session token with their
+ * requests.
+ */
+public class CrawlerSessionManagerValve extends ValveBase {
+
+ private Map<String,SessionInfo> uaIpSessionInfo =
+ new ConcurrentHashMap<String, SessionInfo>();
+
+ private String crawlerUserAgents =
+ ".*GoogleBot.*|.*bingbot.*|.*Yahoo! Slurp.*";
+ private Matcher uaMatcher = null;
+ private int sessionInactiveInterval = 60;
+
+
+ /**
+ * Specify the regular expression (using {@link Pattern}) that will be used
+ * to identify crawlers based in the User-Agent header provided. The
default
+ * is ".*GoogleBot.*|.*bingbot.*|.*Yahoo! Slurp.*"
+ *
+ * @param crawlerUserAgents The regular expression using {@link Pattern}
+ */
+ public void setCrawlerUserAgents(String crawlerUserAgents) {
+ this.crawlerUserAgents = crawlerUserAgents;
+ if (crawlerUserAgents == null || crawlerUserAgents.length() == 0) {
+ uaMatcher = null;
+ } else {
+ uaMatcher = Pattern.compile(crawlerUserAgents).matcher("");
+ }
+ }
+
+ /**
+ * @see #setCrawlerUserAgents(String)
+ * @return The current regular expression being used to match user
agents.
+ */
+ public String getCrawlerUserAgents() {
+ return crawlerUserAgents;
+ }
+
+
+ /**
+ * Specify the session timeout (in seconds) for a crawler's session. This
is
+ * typically lower than that for a user session. The default is 60 seconds.
+ *
+ * @param sessionInactiveInterval The new timeout for crawler sessions
+ */
+ public void setSessionInactiveInterval(int sessionInactiveInterval) {
+ this.sessionInactiveInterval = sessionInactiveInterval;
+ }
+
+ /**
+ * @see #setSessionInactiveInterval(int)
+ * @return The current timeout in seconds
+ */
+ public int getSessionInactiveInterval() {
+ return sessionInactiveInterval;
+ }
+
+
+ @Override
+ protected void initInternal() throws LifecycleException {
+ super.initInternal();
+
+ uaMatcher = Pattern.compile(crawlerUserAgents).matcher("");
+ }
+
+
+ @Override
+ public void invoke(Request request, Response response) throws IOException,
+ ServletException {
+
+ boolean isBot = false;
+ SessionInfo sessionInfo = null;
+ String clientIp = null;
+
+ // If the incoming request has a session ID, no action is required
+ if (request.getRequestedSessionId() == null) {
+
+ // Is this a crawler
+ Enumeration<String> uaHeaders = request.getHeaders("user-agent");
+ while (!isBot && uaMatcher != null &&
+ uaHeaders.hasMoreElements()) {
+ String uaHeader = uaHeaders.nextElement();
+ uaMatcher.reset(uaHeader);
+ if (uaMatcher.matches()) {
+ isBot = true;
+ }
+ }
+
+ // If this is a bot, is the session ID known?
+ if (isBot) {
+ clientIp = request.getRemoteAddr();
+ sessionInfo = uaIpSessionInfo.get(clientIp);
+ if (sessionInfo != null) {
+ request.setRequestedSessionId(sessionInfo.getSessionId());
+ }
+ }
+ }
+
+ getNext().invoke(request, response);
+
+ if (isBot) {
+ if (sessionInfo == null) {
+ // Has bot just created a session, if so make a note of it
+ HttpSession s = request.getSession(false);
+ if (s != null) {
+ uaIpSessionInfo.put(clientIp, new SessionInfo(s.getId()));
+ s.setMaxInactiveInterval(sessionInactiveInterval);
+ }
+ } else {
+ sessionInfo.access();
+ }
+ }
+ }
+
+
+ @Override
+ public void backgroundProcess() {
+ super.backgroundProcess();
+
+ long expireTime = System.currentTimeMillis() +
+ (sessionInactiveInterval + 60) * 1000;
+
+ Iterator<Entry<String,SessionInfo>> iter =
+ uaIpSessionInfo.entrySet().iterator();
+
+ // Remove any sessions in the cache that have expired.
+ while (iter.hasNext()) {
+ Entry<String,SessionInfo> entry = iter.next();
+ if (entry.getValue().getLastAccessed() > expireTime) {
+ iter.remove();
+ }
+ }
+ }
+
+
+ private static final class SessionInfo {
+ private final String sessionId;
+ private volatile long lastAccessed;
+
+ public SessionInfo(String sessionId) {
+ this.sessionId = sessionId;
+ this.lastAccessed = System.currentTimeMillis();
+ }
+
+ public String getSessionId() {
+ return sessionId;
+ }
+
+ public long getLastAccessed() {
+ return lastAccessed;
+ }
+
+ public void access() {
+ lastAccessed = System.currentTimeMillis();
+ }
+ }
+}
Propchange:
tomcat/trunk/java/org/apache/catalina/valves/CrawlerSessionManagerValve.java
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