/* MemorizingTrustManager - a TrustManager which asks the user about invalid
* certificates and memorizes their decision.
*
* Copyright (c) 2010 Georg Lukas <georg@op-co.de>
*
* MemorizingTrustManager.java contains the actual trust manager and interface
* code to create a MemorizingActivity and obtain the results.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package de.duenndns.ssl;
import android.app.Activity;
import android.app.Application;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.Service;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.util.Log;
import android.util.SparseArray;
import android.os.Handler;
import java.io.File;
import java.security.cert.*;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.MessageDigest;
import java.text.SimpleDateFormat;
import java.util.Collection;
import java.util.Enumeration;
import java.util.List;
import java.util.Locale;
import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.SSLSession;
import javax.net.ssl.TrustManager;
import javax.net.ssl.TrustManagerFactory;
import javax.net.ssl.X509TrustManager;
import org.yaxim.androidclient.R;
/**
* A X509 trust manager implementation which asks the user about invalid
* certificates and memorizes their decision.
* <p>
* The certificate validity is checked using the system default X509
* TrustManager, creating a query Dialog if the check fails.
* <p>
* <b>WARNING:</b> This only works if a dedicated thread is used for
* opening sockets!
*/
public class MemorizingTrustManager implements X509TrustManager {
final static String TAG = "MemorizingTrustManager";
final static String DECISION_INTENT = "de.duenndns.ssl.DECISION";
final static String DECISION_INTENT_ID = DECISION_INTENT + ".decisionId";
final static String DECISION_INTENT_CERT = DECISION_INTENT + ".cert";
final static String DECISION_INTENT_CHOICE = DECISION_INTENT + ".decisionChoice";
final static String DECISION_TITLE_ID = DECISION_INTENT + ".titleId";
private final static int NOTIFICATION_ID = 100509;
final static String NO_TRUST_ANCHOR = "Trust anchor for certification path not found.";
static String KEYSTORE_DIR = "KeyStore";
static String KEYSTORE_FILE = "KeyStore.bks";
Context master;
Activity foregroundAct;
NotificationManager notificationManager;
private static int decisionId = 0;
private static SparseArray<MTMDecision> openDecisions = new SparseArray<MTMDecision>();
Handler masterHandler;
private File keyStoreFile;
private KeyStore appKeyStore;
private X509TrustManager defaultTrustManager;
private X509TrustManager appTrustManager;
/** Creates an instance of the MemorizingTrustManager class that falls back to a custom TrustManager.
*
* You need to supply the application context. This has to be one of:
* - Application
* - Activity
* - Service
*
* The context is used for file management, to display the dialog /
* notification and for obtaining translated strings.
*
* @param m Context for the application.
* @param defaultTrustManager Delegate trust management to this TM. If null, the user must accept every certificate.
*/
public MemorizingTrustManager(Context m, X509TrustManager defaultTrustManager) {
init(m);
this.appTrustManager = getTrustManager(appKeyStore);
this.defaultTrustManager = defaultTrustManager;
}
/** Creates an instance of the MemorizingTrustManager class using the system X509TrustManager.
*
* You need to supply the application context. This has to be one of:
* - Application
* - Activity
* - Service
*
* The context is used for file management, to display the dialog /
* notification and for obtaining translated strings.
*
* @param m Context for the application.
*/
public MemorizingTrustManager(Context m) {
init(m);
this.appTrustManager = getTrustManager(appKeyStore);
this.defaultTrustManager = getTrustManager(null);
}
void init(Context m) {
master = m;
masterHandler = new Handler(m.getMainLooper());
notificationManager = (NotificationManager)master.getSystemService(Context.NOTIFICATION_SERVICE);
Application app;
if (m instanceof Application) {
app = (Application)m;
} else if (m instanceof Service) {
app = ((Service)m).getApplication();
} else if (m instanceof Activity) {
app = ((Activity)m).getApplication();
} else throw new ClassCastException("MemorizingTrustManager context must be either Activity or Service!");
File dir = app.getDir(KEYSTORE_DIR, Context.MODE_PRIVATE);
keyStoreFile = new File(dir + File.separator + KEYSTORE_FILE);
appKeyStore = loadAppKeyStore();
}
/**
* Returns a X509TrustManager list containing a new instance of
* TrustManagerFactory.
*
* This function is meant for convenience only. You can use it
* as follows to integrate TrustManagerFactory for HTTPS sockets:
*
* <pre>
* SSLContext sc = SSLContext.getInstance("TLS");
* sc.init(null, MemorizingTrustManager.getInstanceList(this),
* new java.security.SecureRandom());
* HttpsURLConnection.setDefaultSSLSocketFactory(sc.getSocketFactory());
* </pre>
* @param c Activity or Service to show the Dialog / Notification
*/
public static X509TrustManager[] getInstanceList(Context c) {
return new X509TrustManager[] { new MemorizingTrustManager(c) };
}
/**
* Binds an Activity to the MTM for displaying the query dialog.
*
* This is useful if your connection is run from a service that is
* triggered by user interaction -- in such cases the activity is
* visible and the user tends to ignore the service notification.
*
* You should never have a hidden activity bound to MTM! Use this
* function in onResume() and @see unbindDisplayActivity in onPause().
*
* @param act Activity to be bound
*/
public void bindDisplayActivity(Activity act) {
foregroundAct = act;
}
/**
* Removes an Activity from the MTM display stack.
*
* Always call this function when the Activity added with
* @see bindDisplayActivity is hidden.
*
* @param act Activity to be unbound
*/
public void unbindDisplayActivity(Activity act) {
// do not remove if it was overridden by a different activity
if (foregroundAct == act)
foregroundAct = null;
}
/**
* Changes the path for the KeyStore file.
*
* The actual filename relative to the app's directory will be
* <code>app_<i>dirname</i>/<i>filename</i></code>.
*
* @param dirname directory to store the KeyStore.
* @param filename file name for the KeyStore.
*/
public static void setKeyStoreFile(String dirname, String filename) {
KEYSTORE_DIR = dirname;
KEYSTORE_FILE = filename;
}
/**
* Get a list of all certificate aliases stored in MTM.
*
* @return an {@link Enumeration} of all certificates
*/
public Enumeration<String> getCertificates() {
try {
return appKeyStore.aliases();
} catch (KeyStoreException e) {
// this should never happen, however...
throw new RuntimeException(e);
}
}
/**
* Get a certificate for a given alias.
*
* @param alias the certificate's alias as returned by {@link getCertificates}.
*
* @return the certificate associated with the alias or <tt>null</tt> if none found.
*/
public Certificate getCertificate(String alias) {
try {
return appKeyStore.getCertificate(alias);
} catch (KeyStoreException e) {
// this should never happen, however...
throw new RuntimeException(e);
}
}
/**
* Removes the given certificate from MTMs key store.
*
* <p>
* <b>WARNING</b>: this does not immediately invalidate the certificate. It is
* well possible that (a) data is transmitted over still existing connections or
* (b) new connections are created using TLS renegotiation, without a new cert
* check.
* </p>
* @param alias the certificate's alias as returned by {@link getCertificates}.
*
* @throws KeyStoreException if the certificate could not be deleted.
*/
public void deleteCertificate(String alias) throws KeyStoreException {
appKeyStore.deleteEntry(alias);
keyStoreUpdated();
}
/**
* Creates a new hostname verifier supporting user interaction.
*
* <p>This method creates a new {@link HostnameVerifier} that is bound to
* the given instance of {@link MemorizingTrustManager}, and leverages an
* existing {@link HostnameVerifier}. The returned verifier performs the
* following steps, returning as soon as one of them succeeds:
* </p>
* <ol>
* <li>Success, if the wrapped defaultVerifier accepts the certificate.</li>
* <li>Success, if the server certificate is stored in the keystore under the given hostname.</li>
* <li>Ask the user and return accordingly.</li>
* <li>Failure on exception.</li>
* </ol>
*
* @param defaultVerifier the {@link HostnameVerifier} that should perform the actual check
* @return a new hostname verifier using the MTM's key store
*
* @throws IllegalArgumentException if the defaultVerifier parameter is null
*/
public HostnameVerifier wrapHostnameVerifier(final HostnameVerifier defaultVerifier) {
if (defaultVerifier == null)
throw new IllegalArgumentException("The default verifier may not be null");
return new MemorizingHostnameVerifier(defaultVerifier);
}
X509TrustManager getTrustManager(KeyStore ks) {
try {
TrustManagerFactory tmf = TrustManagerFactory.getInstance("X509");
tmf.init(ks);
for (TrustManager t : tmf.getTrustManagers()) {
if (t instanceof X509TrustManager) {
return (X509TrustManager)t;
}
}
} catch (Exception e) {
// Here, we are covering up errors. It might be more useful
// however to throw them out of the constructor so the
// embedding app knows something went wrong.
Log.e(TAG, "getTrustManager(" + ks + ")", e);
}
return null;
}
KeyStore loadAppKeyStore() {
KeyStore ks;
try {
ks = KeyStore.getInstance(KeyStore.getDefaultType());
} catch (KeyStoreException e) {
Log.e(TAG, "getAppKeyStore()", e);
return null;
}
try {
ks.load(null, null);
ks.load(new java.io.FileInputStream(keyStoreFile), "MTM".toCharArray());
} catch (java.io.FileNotFoundException e) {
Log.i(TAG, "getAppKeyStore(" + keyStoreFile + ") - file does not exist");
} catch (Exception e) {
Log.e(TAG, "getAppKeyStore(" + keyStoreFile + ")", e);
}
return ks;
}
void storeCert(String alias, Certificate cert) {
try {
appKeyStore.setCertificateEntry(alias, cert);
} catch (KeyStoreException e) {
Log.e(TAG, "storeCert(" + cert + ")", e);
return;
}
keyStoreUpdated();
}
void storeCert(X509Certificate cert) {
storeCert(cert.getSubjectDN().toString(), cert);
}
void keyStoreUpdated() {
// reload appTrustManager
appTrustManager = getTrustManager(appKeyStore);
// store KeyStore to file
try {
java.io.FileOutputStream fos = new java.io.FileOutputStream(keyStoreFile);
appKeyStore.store(fos, "MTM".toCharArray());
fos.close();
} catch (Exception e) {
Log.e(TAG, "storeCert(" + keyStoreFile + ")", e);
}
}
// if the certificate is stored in the app key store, it is considered "known"
private boolean isCertKnown(X509Certificate cert) {
try {
return appKeyStore.getCertificateAlias(cert) != null;
} catch (KeyStoreException e) {
return false;
}
}
private boolean isExpiredException(Throwable e) {
do {
if (e instanceof CertificateExpiredException)
return true;
e = e.getCause();
} while (e != null);
return false;
}
public void checkCertTrusted(X509Certificate[] chain, String authType, boolean isServer)
throws CertificateException
{
Log.d(TAG, "checkCertTrusted(" + chain + ", " + authType + ", " + isServer + ")");
try {
Log.d(TAG, "checkCertTrusted: trying appTrustManager");
if (isServer)
appTrustManager.checkServerTrusted(chain, authType);
else
appTrustManager.checkClientTrusted(chain, authType);
} catch (CertificateException ae) {
// if the cert is stored in our appTrustManager, we ignore expiredness
ae.printStackTrace();
if (isExpiredException(ae)) {
Log.i(TAG, "checkCertTrusted: accepting expired certificate from keystore");
return;
}
if (isCertKnown(chain[0])) {
Log.i(TAG, "checkCertTrusted: accepting cert already stored in keystore");
return;
}
try {
if (defaultTrustManager == null)
throw ae;
Log.d(TAG, "checkCertTrusted: trying defaultTrustManager");
if (isServer)
defaultTrustManager.checkServerTrusted(chain, authType);
else
defaultTrustManager.checkClientTrusted(chain, authType);
} catch (CertificateException e) {
e.printStackTrace();
interactCert(chain, authType, e);
}
}
}
public void checkClientTrusted(X509Certificate[] chain, String authType)
throws CertificateException
{
checkCertTrusted(chain, authType, false);
}
public void checkServerTrusted(X509Certificate[] chain, String authType)
throws CertificateException
{
checkCertTrusted(chain, authType, true);
}
public X509Certificate[] getAcceptedIssuers()
{
Log.d(TAG, "getAcceptedIssuers()");
return defaultTrustManager.getAcceptedIssuers();
}
private int createDecisionId(MTMDecision d) {
int myId;
synchronized(openDecisions) {
myId = decisionId;
openDecisions.put(myId, d);
decisionId += 1;
}
return myId;
}
private static String hexString(byte[] data) {
StringBuffer si = new StringBuffer();
for (int i = 0; i < data.length; i++) {
si.append(String.format("%02x", data[i]));
if (i < data.length - 1)
si.append(":");
}
return si.toString();
}
private static String certHash(final X509Certificate cert, String digest) {
try {
MessageDigest md = MessageDigest.getInstance(digest);
md.update(cert.getEncoded());
return hexString(md.digest());
} catch (java.security.cert.CertificateEncodingException e) {
return e.getMessage();
} catch (java.security.NoSuchAlgorithmException e) {
return e.getMessage();
}
}
private void certDetails(StringBuffer si, X509Certificate c) {
SimpleDateFormat validityDateFormater = new SimpleDateFormat("yyyy-MM-dd");
si.append("\n");
si.append(c.getSubjectDN().toString());
si.append("\n");
si.append(validityDateFormater.format(c.getNotBefore()));
si.append(" - ");
si.append(validityDateFormater.format(c.getNotAfter()));
si.append("\nSHA-256: ");
si.append(certHash(c, "SHA-256"));
si.append("\nSHA-1: ");
si.append(certHash(c, "SHA-1"));
si.append("\nSigned by: ");
si.append(c.getIssuerDN().toString());
si.append("\n");
}
private String certChainMessage(final X509Certificate[] chain, CertificateException cause) {
Throwable e = cause;
Log.d(TAG, "certChainMessage for " + e);
StringBuffer si = new StringBuffer();
if (e.getCause() != null) {
e = e.getCause();
// HACK: there is no sane way to check if the error is a "trust anchor
// not found", so we use string comparison.
if (NO_TRUST_ANCHOR.equals(e.getMessage())) {
si.append(master.getString(R.string.mtm_trust_anchor));
} else
si.append(e.getLocalizedMessage());
si.append("\n");
}
si.append("\n");
si.append(master.getString(R.string.mtm_connect_anyway));
si.append("\n\n");
si.append(master.getString(R.string.mtm_cert_details));
for (X509Certificate c : chain) {
certDetails(si, c);
}
return si.toString();
}
private String hostNameMessage(X509Certificate cert, String hostname) {
StringBuffer si = new StringBuffer();
si.append(master.getString(R.string.mtm_hostname_mismatch, hostname));
si.append("\n\n");
try {
Collection<List<?>> sans = cert.getSubjectAlternativeNames();
if (sans == null) {
si.append(cert.getSubjectDN());
si.append("\n");
} else for (List<?> altName : sans) {
Object name = altName.get(1);
if (name instanceof String) {
si.append("[");
si.append((Integer)altName.get(0));
si.append("] ");
si.append(name);
si.append("\n");
}
}
} catch (CertificateParsingException e) {
e.printStackTrace();
si.append("<Parsing error: ");
si.append(e.getLocalizedMessage());
si.append(">\n");
}
si.append("\n");
si.append(master.getString(R.string.mtm_connect_anyway));
si.append("\n\n");
si.append(master.getString(R.string.mtm_cert_details));
certDetails(si, cert);
return si.toString();
}
void startActivityNotification(Intent intent, int decisionId, String certName) {
Notification n = new Notification(android.R.drawable.ic_lock_lock,
master.getString(R.string.mtm_notification),
System.currentTimeMillis());
PendingIntent call = PendingIntent.getActivity(master, 0, intent, 0);
n.setLatestEventInfo(master.getApplicationContext(),
master.getString(R.string.mtm_notification),
certName, call);
n.flags |= Notification.FLAG_AUTO_CANCEL;
notificationManager.notify(NOTIFICATION_ID + decisionId, n);
}
/**
* Returns the top-most entry of the activity stack.
*
* @return the Context of the currently bound UI or the master context if none is bound
*/
Context getUI() {
return (foregroundAct != null) ? foregroundAct : master;
}
int interact(final String message, final int titleId) {
/* prepare the MTMDecision blocker object */
MTMDecision choice = new MTMDecision();
final int myId = createDecisionId(choice);
masterHandler.post(new Runnable() {
public void run() {
Intent ni = new Intent(master, MemorizingActivity.class);
ni.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
ni.setData(Uri.parse(MemorizingTrustManager.class.getName() + "/" + myId));
ni.putExtra(DECISION_INTENT_ID, myId);
ni.putExtra(DECISION_INTENT_CERT, message);
ni.putExtra(DECISION_TITLE_ID, titleId);
// we try to directly start the activity and fall back to
// making a notification
try {
getUI().startActivity(ni);
} catch (Exception e) {
Log.e(TAG, "startActivity: " + e);
startActivityNotification(ni, myId, message);
}
}
});
Log.d(TAG, "openDecisions: " + openDecisions);
Log.d(TAG, "waiting on " + myId);
try {
synchronized(choice) { choice.wait(); }
} catch (InterruptedException e) {
e.printStackTrace();
}
Log.d(TAG, "finished wait on " + myId + ": " + choice.state);
return choice.state;
}
void interactCert(final X509Certificate[] chain, String authType, CertificateException cause)
throws CertificateException
{
switch (interact(certChainMessage(chain, cause), R.string.mtm_accept_cert)) {
case MTMDecision.DECISION_ALWAYS:
storeCert(chain[0]); // only store the server cert, not the whole chain
case MTMDecision.DECISION_ONCE:
break;
default:
throw (cause);
}
}
boolean interactHostname(X509Certificate cert, String hostname)
{
switch (interact(hostNameMessage(cert, hostname), R.string.mtm_accept_servername)) {
case MTMDecision.DECISION_ALWAYS:
storeCert(hostname, cert);
case MTMDecision.DECISION_ONCE:
return true;
default:
return false;
}
}
protected static void interactResult(int decisionId, int choice) {
MTMDecision d;
synchronized(openDecisions) {
d = openDecisions.get(decisionId);
openDecisions.remove(decisionId);
}
if (d == null) {
Log.e(TAG, "interactResult: aborting due to stale decision reference!");
return;
}
synchronized(d) {
d.state = choice;
d.notify();
}
}
class MemorizingHostnameVerifier implements HostnameVerifier {
private HostnameVerifier defaultVerifier;
public MemorizingHostnameVerifier(HostnameVerifier wrapped) {
defaultVerifier = wrapped;
}
@Override
public boolean verify(String hostname, SSLSession session) {
Log.d(TAG, "hostname verifier for " + hostname + ", trying default verifier first");
// if the default verifier accepts the hostname, we are done
if (defaultVerifier.verify(hostname, session)) {
Log.d(TAG, "default verifier accepted " + hostname);
return true;
}
// otherwise, we check if the hostname is an alias for this cert in our keystore
try {
X509Certificate cert = (X509Certificate)session.getPeerCertificates()[0];
//Log.d(TAG, "cert: " + cert);
if (cert.equals(appKeyStore.getCertificate(hostname.toLowerCase(Locale.US)))) {
Log.d(TAG, "certificate for " + hostname + " is in our keystore. accepting.");
return true;
} else {
Log.d(TAG, "server " + hostname + " provided wrong certificate, asking user.");
return interactHostname(cert, hostname);
}
} catch (Exception e) {
e.printStackTrace();
return false;
}
}
}
}