/*
* $Header: /home/cvs/jakarta-commons/httpclient/src/contrib/org/apache/commons/httpclient/contrib/ssl/StrictSSLProtocolSocketFactory.java,v 1.1 2003/05/17 15:40:00 olegk Exp $
* $Revision: 1.1 $
* $Date: 2003/05/17 15:40:00 $
*
* ====================================================================
*
* The Apache Software License, Version 1.1
*
* Copyright (c) 1999-2003 The Apache Software Foundation. All rights
* reserved.
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*
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package org.apache.commons.httpclient.contrib.ssl;
import java.io.IOException;
import java.net.InetAddress;
import java.net.Socket;
import java.net.UnknownHostException;
import javax.net.ssl.SSLPeerUnverifiedException;
import javax.net.ssl.SSLSession;
import javax.net.ssl.SSLSocket;
import javax.net.ssl.SSLSocketFactory;
import javax.security.cert.X509Certificate;
import org.apache.commons.httpclient.protocol.SecureProtocolSocketFactory;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* A <code>SecureProtocolSocketFactory</code> that uses JSSE to create
* SSL sockets. It will also support host name verification to help preventing
* man-in-the-middle attacks. Host name verification is turned <b>on</b> by
* default but one will be able to turn it off, which might be a useful feature
* during development. Host name verification will make sure the SSL sessions
* server host name matches with the the host name returned in the
* server certificates "Common Name" field of the "SubjectDN" entry.
*
* @author <a href="mailto:hauer@psicode.com">Sebastian Hauer</a>
* @version 1.0
*
* DISCLAIMER: HttpClient developers DO NOT actively support this component.
* The component is provided as a reference material, which may be inappropriate
* to be used without additional customization.
*/
public class StrictSSLProtocolSocketFactory
implements SecureProtocolSocketFactory {
/** Log object for this class. */
private static final Log LOG = LogFactory.getLog(StrictSSLProtocolSocketFactory.class);
/** Host name verify flag. */
private boolean verifyHostname = true;
/**
* Constructor for StrictSSLProtocolSocketFactory.
* @param verifyHostname The host name verification flag. If set to
* <code>true</code> the SSL sessions server host name will be compared
* to the host name returned in the server certificates "Common Name"
* field of the "SubjectDN" entry. If these names do not match a
* Exception is thrown to indicate this. Enabling host name verification
* will help to prevent from man-in-the-middle attacks. If set to
* <code>false</code> host name verification is turned off.
*
* Code sample:
*
* <blockquote>
* Protocol stricthttps = new Protocol(
* "https", new StrictSSLProtocolSocketFactory(true), 443);
*
* HttpClient client = new HttpClient();
* client.getHostConfiguration().setHost("localhost", 443, stricthttps);
* </blockquote>
*
*/
public StrictSSLProtocolSocketFactory(boolean verifyHostname) {
super();
this.verifyHostname = verifyHostname;
}
/**
* Constructor for StrictSSLProtocolSocketFactory.
* Host name verification will be enabled by default.
*/
public StrictSSLProtocolSocketFactory() {
super();
}
/**
* Set the host name verification flag.
*
* @param verifyHostname The host name verification flag. If set to
* <code>true</code> the SSL sessions server host name will be compared
* to the host name returned in the server certificates "Common Name"
* field of the "SubjectDN" entry. If these names do not match a
* Exception is thrown to indicate this. Enabling host name verification
* will help to prevent from man-in-the-middle attacks. If set to
* <code>false</code> host name verification is turned off.
*/
public void setHostnameVerification(boolean verifyHostname) {
this.verifyHostname = verifyHostname;
}
/**
* Gets the status of the host name verification flag.
*
* @return Host name verification flag. Either <code>true</code> if host
* name verification is turned on, or <code>false</code> if host name
* verification is turned off.
*/
public boolean getHostnameVerification() {
return verifyHostname;
}
/**
* @see SecureProtocolSocketFactory#createSocket(java.lang.String,int,java.net.InetAddress,int)
*/
public Socket createSocket(String host, int port,
InetAddress clientHost, int clientPort)
throws IOException, UnknownHostException {
SSLSocketFactory sf = (SSLSocketFactory) SSLSocketFactory.getDefault();
SSLSocket sslSocket = (SSLSocket) sf.createSocket(host, port,
clientHost,
clientPort);
verifyHostname(sslSocket);
return sslSocket;
}
/**
* @see SecureProtocolSocketFactory#createSocket(java.lang.String,int)
*/
public Socket createSocket(String host, int port)
throws IOException, UnknownHostException {
SSLSocketFactory sf = (SSLSocketFactory) SSLSocketFactory.getDefault();
SSLSocket sslSocket = (SSLSocket) sf.createSocket(host, port);
verifyHostname(sslSocket);
return sslSocket;
}
/**
* @see SecureProtocolSocketFactory#createSocket(java.net.Socket,java.lang.String,int,boolean)
*/
public Socket createSocket(Socket socket, String host, int port,
boolean autoClose)
throws IOException, UnknownHostException {
SSLSocketFactory sf = (SSLSocketFactory) SSLSocketFactory.getDefault();
SSLSocket sslSocket = (SSLSocket) sf.createSocket(socket, host,
port, autoClose);
verifyHostname(sslSocket);
return sslSocket;
}
/**
* Describe <code>verifyHostname</code> method here.
*
* @param socket a <code>SSLSocket</code> value
* @exception SSLPeerUnverifiedException If there are problems obtaining
* the server certificates from the SSL session, or the server host name
* does not match with the "Common Name" in the server certificates
* SubjectDN.
* @exception UnknownHostException If we are not able to resolve
* the SSL sessions returned server host name.
*/
private void verifyHostname(SSLSocket socket)
throws SSLPeerUnverifiedException, UnknownHostException {
if (! verifyHostname)
return;
SSLSession session = socket.getSession();
String hostname = session.getPeerHost();
try {
InetAddress addr = InetAddress.getByName(hostname);
} catch (UnknownHostException uhe) {
throw new UnknownHostException("Could not resolve SSL sessions "
+ "server hostname: " + hostname);
}
X509Certificate[] certs = session.getPeerCertificateChain();
if (certs == null || certs.length == 0)
throw new SSLPeerUnverifiedException("No server certificates found!");
//get the servers DN in its string representation
String dn = certs[0].getSubjectDN().getName();
//might be useful to print out all certificates we receive from the
//server, in case one has to debug a problem with the installed certs.
if (LOG.isDebugEnabled()) {
LOG.debug("Server certificate chain:");
for (int i = 0; i < certs.length; i++) {
LOG.debug("X509Certificate[" + i + "]=" + certs[i]);
}
}
//get the common name from the first cert
String cn = getCN(dn);
if (hostname.equalsIgnoreCase(cn)) {
if (LOG.isDebugEnabled()) {
LOG.debug("Target hostname valid: " + cn);
}
} else {
throw new SSLPeerUnverifiedException(
"HTTPS hostname invalid: expected '" + hostname + "', received '" + cn + "'");
}
}
/**
* Parses a X.500 distinguished name for the value of the
* "Common Name" field.
* This is done a bit sloppy right now and should probably be done a bit
* more according to <code>RFC 2253</code>.
*
* @param dn a X.500 distinguished name.
* @return the value of the "Common Name" field.
*/
private String getCN(String dn) {
int i = 0;
i = dn.indexOf("CN=");
if (i == -1) {
return null;
}
//get the remaining DN without CN=
dn = dn.substring(i + 3);
// System.out.println("dn=" + dn);
char[] dncs = dn.toCharArray();
for (i = 0; i < dncs.length; i++) {
if (dncs[i] == ',' && i > 0 && dncs[i - 1] != '\\') {
break;
}
}
return dn.substring(0, i);
}
}