org.eclipse.jetty.servlets.BalancerServlet Maven / Gradle / Ivy
//
// ========================================================================
// Copyright (c) 1995-2013 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
//
// The Eclipse Public License is available at
// http://www.eclipse.org/legal/epl-v10.html
//
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
//
// You may elect to redistribute this code under either of these licenses.
// ========================================================================
//
package org.eclipse.jetty.servlets;
import java.net.MalformedURLException;
import java.net.URI;
import java.net.URISyntaxException;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;
import java.util.concurrent.atomic.AtomicInteger;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.UnavailableException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import org.eclipse.jetty.http.HttpURI;
import org.eclipse.jetty.server.Request;
/**
* 6
*/
public class BalancerServlet extends ProxyServlet
{
private static final class BalancerMember
{
private String _name;
private String _proxyTo;
private HttpURI _backendURI;
public BalancerMember(String name, String proxyTo)
{
super();
_name = name;
_proxyTo = proxyTo;
_backendURI = new HttpURI(_proxyTo);
}
public String getProxyTo()
{
return _proxyTo;
}
public HttpURI getBackendURI()
{
return _backendURI;
}
@Override
public String toString()
{
return "BalancerMember [_name=" + _name + ", _proxyTo=" + _proxyTo + "]";
}
@Override
public int hashCode()
{
final int prime = 31;
int result = 1;
result = prime * result + ((_name == null)?0:_name.hashCode());
return result;
}
@Override
public boolean equals(Object obj)
{
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
BalancerMember other = (BalancerMember)obj;
if (_name == null)
{
if (other._name != null)
return false;
}
else if (!_name.equals(other._name))
return false;
return true;
}
}
private static final class RoundRobinIterator implements Iterator
{
private BalancerMember[] _balancerMembers;
private AtomicInteger _index;
public RoundRobinIterator(Collection balancerMembers)
{
_balancerMembers = (BalancerMember[])balancerMembers.toArray(new BalancerMember[balancerMembers.size()]);
_index = new AtomicInteger(-1);
}
public boolean hasNext()
{
return true;
}
public BalancerMember next()
{
BalancerMember balancerMember = null;
while (balancerMember == null)
{
int currentIndex = _index.get();
int nextIndex = (currentIndex + 1) % _balancerMembers.length;
if (_index.compareAndSet(currentIndex,nextIndex))
{
balancerMember = _balancerMembers[nextIndex];
}
}
return balancerMember;
}
public void remove()
{
throw new UnsupportedOperationException();
}
}
private static final String BALANCER_MEMBER_PREFIX = "BalancerMember.";
private static final List FORBIDDEN_CONFIG_PARAMETERS;
static
{
List params = new LinkedList();
params.add("HostHeader");
params.add("whiteList");
params.add("blackList");
FORBIDDEN_CONFIG_PARAMETERS = Collections.unmodifiableList(params);
}
private static final List REVERSE_PROXY_HEADERS;
static
{
List params = new LinkedList();
params.add("Location");
params.add("Content-Location");
params.add("URI");
REVERSE_PROXY_HEADERS = Collections.unmodifiableList(params);
}
private static final String JSESSIONID = "jsessionid";
private static final String JSESSIONID_URL_PREFIX = JSESSIONID + "=";
private boolean _stickySessions;
private Set _balancerMembers = new HashSet();
private boolean _proxyPassReverse;
private RoundRobinIterator _roundRobinIterator;
@Override
public void init(ServletConfig config) throws ServletException
{
validateConfig(config);
super.init(config);
initStickySessions(config);
initBalancers(config);
initProxyPassReverse(config);
postInit();
}
private void validateConfig(ServletConfig config) throws ServletException
{
@SuppressWarnings("unchecked")
List initParameterNames = Collections.list(config.getInitParameterNames());
for (String initParameterName : initParameterNames)
{
if (FORBIDDEN_CONFIG_PARAMETERS.contains(initParameterName))
{
throw new UnavailableException(initParameterName + " not supported in " + getClass().getName());
}
}
}
private void initStickySessions(ServletConfig config) throws ServletException
{
_stickySessions = "true".equalsIgnoreCase(config.getInitParameter("StickySessions"));
}
private void initBalancers(ServletConfig config) throws ServletException
{
Set balancerNames = getBalancerNames(config);
for (String balancerName : balancerNames)
{
String memberProxyToParam = BALANCER_MEMBER_PREFIX + balancerName + ".ProxyTo";
String proxyTo = config.getInitParameter(memberProxyToParam);
if (proxyTo == null || proxyTo.trim().length() == 0)
{
throw new UnavailableException(memberProxyToParam + " parameter is empty.");
}
_balancerMembers.add(new BalancerMember(balancerName,proxyTo));
}
}
private void initProxyPassReverse(ServletConfig config)
{
_proxyPassReverse = "true".equalsIgnoreCase(config.getInitParameter("ProxyPassReverse"));
}
private void postInit()
{
_roundRobinIterator = new RoundRobinIterator(_balancerMembers);
}
private Set getBalancerNames(ServletConfig config) throws ServletException
{
Set names = new HashSet();
@SuppressWarnings("unchecked")
List initParameterNames = Collections.list(config.getInitParameterNames());
for (String initParameterName : initParameterNames)
{
if (!initParameterName.startsWith(BALANCER_MEMBER_PREFIX))
{
continue;
}
int endOfNameIndex = initParameterName.lastIndexOf(".");
if (endOfNameIndex <= BALANCER_MEMBER_PREFIX.length())
{
throw new UnavailableException(initParameterName + " parameter does not provide a balancer member name");
}
names.add(initParameterName.substring(BALANCER_MEMBER_PREFIX.length(),endOfNameIndex));
}
return names;
}
@Override
protected HttpURI proxyHttpURI(HttpServletRequest request, String uri) throws MalformedURLException
{
BalancerMember balancerMember = selectBalancerMember(request);
try
{
URI dstUri = new URI(balancerMember.getProxyTo() + "/" + uri).normalize();
return new HttpURI(dstUri.toString());
}
catch (URISyntaxException e)
{
throw new MalformedURLException(e.getMessage());
}
}
private BalancerMember selectBalancerMember(HttpServletRequest request)
{
BalancerMember balancerMember = null;
if (_stickySessions)
{
String name = getBalancerMemberNameFromSessionId(request);
if (name != null)
{
balancerMember = findBalancerMemberByName(name);
if (balancerMember != null)
{
return balancerMember;
}
}
}
return _roundRobinIterator.next();
}
private BalancerMember findBalancerMemberByName(String name)
{
BalancerMember example = new BalancerMember(name,"");
for (BalancerMember balancerMember : _balancerMembers)
{
if (balancerMember.equals(example))
{
return balancerMember;
}
}
return null;
}
private String getBalancerMemberNameFromSessionId(HttpServletRequest request)
{
String name = getBalancerMemberNameFromSessionCookie(request);
if (name == null)
{
name = getBalancerMemberNameFromURL(request);
}
return name;
}
private String getBalancerMemberNameFromSessionCookie(HttpServletRequest request)
{
Cookie[] cookies = request.getCookies();
String name = null;
for (Cookie cookie : cookies)
{
if (JSESSIONID.equalsIgnoreCase(cookie.getName()))
{
name = extractBalancerMemberNameFromSessionId(cookie.getValue());
break;
}
}
return name;
}
private String getBalancerMemberNameFromURL(HttpServletRequest request)
{
String name = null;
String requestURI = request.getRequestURI();
int idx = requestURI.lastIndexOf(";");
if (idx != -1)
{
String requestURISuffix = requestURI.substring(idx);
if (requestURISuffix.startsWith(JSESSIONID_URL_PREFIX))
{
name = extractBalancerMemberNameFromSessionId(requestURISuffix.substring(JSESSIONID_URL_PREFIX.length()));
}
}
return name;
}
private String extractBalancerMemberNameFromSessionId(String sessionId)
{
String name = null;
int idx = sessionId.lastIndexOf(".");
if (idx != -1)
{
String sessionIdSuffix = sessionId.substring(idx + 1);
name = (sessionIdSuffix.length() > 0)?sessionIdSuffix:null;
}
return name;
}
@Override
protected String filterResponseHeaderValue(String headerName, String headerValue, HttpServletRequest request)
{
if (_proxyPassReverse && REVERSE_PROXY_HEADERS.contains(headerName))
{
HttpURI locationURI = new HttpURI(headerValue);
if (isAbsoluteLocation(locationURI) && isBackendLocation(locationURI))
{
Request jettyRequest = (Request)request;
URI reverseUri;
try
{
reverseUri = new URI(jettyRequest.getRootURL().append(locationURI.getCompletePath()).toString()).normalize();
return reverseUri.toURL().toString();
}
catch (Exception e)
{
_log.warn("Not filtering header response",e);
return headerValue;
}
}
}
return headerValue;
}
private boolean isBackendLocation(HttpURI locationURI)
{
for (BalancerMember balancerMember : _balancerMembers)
{
HttpURI backendURI = balancerMember.getBackendURI();
if (backendURI.getHost().equals(locationURI.getHost()) && backendURI.getScheme().equals(locationURI.getScheme())
&& backendURI.getPort() == locationURI.getPort())
{
return true;
}
}
return false;
}
private boolean isAbsoluteLocation(HttpURI locationURI)
{
return locationURI.getHost() != null;
}
@Override
public String getHostHeader()
{
throw new UnsupportedOperationException("HostHeader not supported in " + getClass().getName());
}
@Override
public void setHostHeader(String hostHeader)
{
throw new UnsupportedOperationException("HostHeader not supported in " + getClass().getName());
}
@Override
public boolean validateDestination(String host, String path)
{
return true;
}
}