org.eclipse.jetty.ee9.proxy.BalancerServlet Maven / Gradle / Ivy
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//
// ========================================================================
// Copyright (c) 1995 Mort Bay Consulting Pty Ltd and others.
//
// This program and the accompanying materials are made available under the
// terms of the Eclipse Public License v. 2.0 which is available at
// https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
// which is available at https://www.apache.org/licenses/LICENSE-2.0.
//
// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
// ========================================================================
//
package org.eclipse.jetty.ee9.proxy;
import java.net.URI;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;
import java.util.concurrent.atomic.AtomicLong;
import jakarta.servlet.ServletException;
import jakarta.servlet.UnavailableException;
import jakarta.servlet.http.Cookie;
import jakarta.servlet.http.HttpServletRequest;
import org.eclipse.jetty.client.Response;
import org.eclipse.jetty.util.URIUtil;
public class BalancerServlet extends ProxyServlet
{
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 final List _balancerMembers = new ArrayList<>();
private final AtomicLong counter = new AtomicLong();
private boolean _stickySessions;
private boolean _proxyPassReverse;
@Override
public void init() throws ServletException
{
validateConfig();
super.init();
initStickySessions();
initBalancers();
initProxyPassReverse();
}
private void validateConfig() throws ServletException
{
for (String initParameterName : Collections.list(getServletConfig().getInitParameterNames()))
{
if (FORBIDDEN_CONFIG_PARAMETERS.contains(initParameterName))
{
throw new UnavailableException(initParameterName + " not supported in " + getClass().getName());
}
}
}
private void initStickySessions()
{
_stickySessions = Boolean.parseBoolean(getServletConfig().getInitParameter("stickySessions"));
}
private void initBalancers() throws ServletException
{
Set members = new HashSet<>();
for (String balancerName : getBalancerNames())
{
String memberProxyToParam = BALANCER_MEMBER_PREFIX + balancerName + ".proxyTo";
String proxyTo = getServletConfig().getInitParameter(memberProxyToParam);
if (proxyTo == null || proxyTo.trim().length() == 0)
throw new UnavailableException(memberProxyToParam + " parameter is empty.");
members.add(new BalancerMember(balancerName, proxyTo));
}
_balancerMembers.addAll(members);
}
private void initProxyPassReverse()
{
_proxyPassReverse = Boolean.parseBoolean(getServletConfig().getInitParameter("proxyPassReverse"));
}
private Set getBalancerNames() throws ServletException
{
Set names = new HashSet<>();
for (String initParameterName : Collections.list(getServletConfig().getInitParameterNames()))
{
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 String rewriteTarget(HttpServletRequest request)
{
BalancerMember balancerMember = selectBalancerMember(request);
if (_log.isDebugEnabled())
_log.debug("Selected {}", balancerMember);
String path = request.getRequestURI();
String query = request.getQueryString();
if (query != null)
path += "?" + query;
return URI.create(balancerMember.getProxyTo() + "/" + path).normalize().toString();
}
private BalancerMember selectBalancerMember(HttpServletRequest request)
{
if (_stickySessions)
{
String name = getBalancerMemberNameFromSessionId(request);
if (name != null)
{
BalancerMember balancerMember = findBalancerMemberByName(name);
if (balancerMember != null)
return balancerMember;
}
}
int index = (int)(counter.getAndIncrement() % _balancerMembers.size());
return _balancerMembers.get(index);
}
private BalancerMember findBalancerMemberByName(String name)
{
for (BalancerMember balancerMember : _balancerMembers)
{
if (balancerMember.getName().equals(name))
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();
if (cookies != null)
{
for (Cookie cookie : cookies)
{
if (JSESSIONID.equalsIgnoreCase(cookie.getName()))
return extractBalancerMemberNameFromSessionId(cookie.getValue());
}
}
return null;
}
private String getBalancerMemberNameFromURL(HttpServletRequest request)
{
String requestURI = request.getRequestURI();
int idx = requestURI.lastIndexOf(";");
if (idx > 0)
{
String requestURISuffix = requestURI.substring(idx + 1);
if (requestURISuffix.startsWith(JSESSIONID_URL_PREFIX))
return extractBalancerMemberNameFromSessionId(requestURISuffix.substring(JSESSIONID_URL_PREFIX.length()));
}
return null;
}
private String extractBalancerMemberNameFromSessionId(String sessionId)
{
int idx = sessionId.lastIndexOf(".");
if (idx > 0)
{
String sessionIdSuffix = sessionId.substring(idx + 1);
return sessionIdSuffix.length() > 0 ? sessionIdSuffix : null;
}
return null;
}
@Override
protected String filterServerResponseHeader(HttpServletRequest request, Response serverResponse, String headerName, String headerValue)
{
if (_proxyPassReverse && REVERSE_PROXY_HEADERS.contains(headerName))
{
URI locationURI = URI.create(headerValue).normalize();
if (locationURI.isAbsolute() && isBackendLocation(locationURI))
{
StringBuilder newURI = URIUtil.newURIBuilder(request.getScheme(), request.getServerName(), request.getServerPort());
String component = locationURI.getRawPath();
if (component != null)
newURI.append(component);
component = locationURI.getRawQuery();
if (component != null)
newURI.append('?').append(component);
component = locationURI.getRawFragment();
if (component != null)
newURI.append('#').append(component);
return URI.create(newURI.toString()).normalize().toString();
}
}
return headerValue;
}
private boolean isBackendLocation(URI locationURI)
{
for (BalancerMember balancerMember : _balancerMembers)
{
URI backendURI = balancerMember.getBackendURI();
if (backendURI.getHost().equals(locationURI.getHost()) &&
backendURI.getScheme().equals(locationURI.getScheme()) &&
backendURI.getPort() == locationURI.getPort())
{
return true;
}
}
return false;
}
@Override
public boolean validateDestination(String host, int port)
{
return true;
}
private static class BalancerMember
{
private final String _name;
private final String _proxyTo;
private final URI _backendURI;
public BalancerMember(String name, String proxyTo)
{
_name = name;
_proxyTo = proxyTo;
_backendURI = URI.create(_proxyTo).normalize();
}
public String getName()
{
return _name;
}
public String getProxyTo()
{
return _proxyTo;
}
public URI getBackendURI()
{
return _backendURI;
}
@Override
public String toString()
{
return String.format("%s[name=%s,proxyTo=%s]", getClass().getSimpleName(), _name, _proxyTo);
}
@Override
public int hashCode()
{
return _name.hashCode();
}
@Override
public boolean equals(Object obj)
{
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
BalancerMember that = (BalancerMember)obj;
return _name.equals(that._name);
}
}
}