SessionIdGeneratorBase.java
/*
* 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.util;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.SecureRandom;
import java.security.Security;
import java.util.Queue;
import java.util.Set;
import java.util.concurrent.ConcurrentLinkedQueue;
import org.apache.catalina.LifecycleException;
import org.apache.catalina.LifecycleState;
import org.apache.catalina.SessionIdGenerator;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;
import org.apache.tomcat.util.res.StringManager;
public abstract class SessionIdGeneratorBase extends LifecycleBase implements SessionIdGenerator {
private final Log log = LogFactory.getLog(SessionIdGeneratorBase.class); // must not be static
private static final StringManager sm = StringManager.getManager("org.apache.catalina.util");
public static final String DEFAULT_SECURE_RANDOM_ALGORITHM;
static {
/*
* The default is normally SHA1PRNG. This was chosen because a) it is
* quick and b) it available by default in all JREs. However, it may not
* be available in some configurations such as those that use a FIPS
* certified provider. In those cases, use the platform default.
*/
Set<String> algorithmNames = Security.getAlgorithms("SecureRandom");
if (algorithmNames.contains("SHA1PRNG")) {
DEFAULT_SECURE_RANDOM_ALGORITHM = "SHA1PRNG";
} else {
// Empty string - This will trigger the use of the platform default.
DEFAULT_SECURE_RANDOM_ALGORITHM = "";
Log log = LogFactory.getLog(SessionIdGeneratorBase.class);
log.warn(sm.getString("sessionIdGeneratorBase.noSHA1PRNG"));
}
}
/**
* Queue of random number generator objects to be used when creating session
* identifiers. If the queue is empty when a random number generator is
* required, a new random number generator object is created. This is
* designed this way since random number generators use a sync to make them
* thread-safe and the sync makes using a single object slow(er).
*/
private final Queue<SecureRandom> randoms = new ConcurrentLinkedQueue<>();
private String secureRandomClass = null;
private String secureRandomAlgorithm = DEFAULT_SECURE_RANDOM_ALGORITHM;
private String secureRandomProvider = null;
/** Node identifier when in a cluster. Defaults to the empty string. */
private String jvmRoute = "";
/** Number of bytes in a session ID. Defaults to 16. */
private int sessionIdLength = 16;
/**
* Get the class name of the {@link SecureRandom} implementation used to
* generate session IDs.
*
* @return The fully qualified class name. {@code null} indicates that the
* JRE provided {@link SecureRandom} implementation will be used
*/
public String getSecureRandomClass() {
return secureRandomClass;
}
/**
* Specify a non-default {@link SecureRandom} implementation to use. The
* implementation must be self-seeding and have a zero-argument constructor.
* If not specified, an instance of {@link SecureRandom} will be generated.
*
* @param secureRandomClass The fully-qualified class name
*/
public void setSecureRandomClass(String secureRandomClass) {
this.secureRandomClass = secureRandomClass;
}
/**
* Get the name of the algorithm used to create the {@link SecureRandom}
* instances which generate new session IDs.
*
* @return The name of the algorithm. {@code null} or the empty string means
* that platform default will be used
*/
public String getSecureRandomAlgorithm() {
return secureRandomAlgorithm;
}
/**
* Specify a non-default algorithm to use to create instances of
* {@link SecureRandom} which are used to generate session IDs. If no
* algorithm is specified, SHA1PRNG will be used. If SHA1PRNG is not
* available, the platform default will be used. To use the platform default
* (which may be SHA1PRNG), specify {@code null} or the empty string. If an
* invalid algorithm and/or provider is specified the {@link SecureRandom}
* instances will be created using the defaults for this
* {@link SessionIdGenerator} implementation. If that fails, the
* {@link SecureRandom} instances will be created using platform defaults.
*
* @param secureRandomAlgorithm The name of the algorithm
*/
public void setSecureRandomAlgorithm(String secureRandomAlgorithm) {
this.secureRandomAlgorithm = secureRandomAlgorithm;
}
/**
* Get the name of the provider used to create the {@link SecureRandom}
* instances which generate new session IDs.
*
* @return The name of the provider. {@code null} or the empty string means
* that platform default will be used
*/
public String getSecureRandomProvider() {
return secureRandomProvider;
}
/**
* Specify a non-default provider to use to create instances of
* {@link SecureRandom} which are used to generate session IDs. If no
* provider is specified, the platform default is used. To use the platform
* default specify {@code null} or the empty string. If an invalid algorithm
* and/or provider is specified the {@link SecureRandom} instances will be
* created using the defaults for this {@link SessionIdGenerator}
* implementation. If that fails, the {@link SecureRandom} instances will be
* created using platform defaults.
*
* @param secureRandomProvider The name of the provider
*/
public void setSecureRandomProvider(String secureRandomProvider) {
this.secureRandomProvider = secureRandomProvider;
}
@Override
public String getJvmRoute() {
return jvmRoute;
}
@Override
public void setJvmRoute(String jvmRoute) {
this.jvmRoute = jvmRoute;
}
@Override
public int getSessionIdLength() {
return sessionIdLength;
}
@Override
public void setSessionIdLength(int sessionIdLength) {
this.sessionIdLength = sessionIdLength;
}
@Override
public String generateSessionId() {
return generateSessionId(jvmRoute);
}
protected void getRandomBytes(byte bytes[]) {
SecureRandom random = randoms.poll();
if (random == null) {
random = createSecureRandom();
}
random.nextBytes(bytes);
randoms.add(random);
}
/**
* Create a new random number generator instance we should use for
* generating session identifiers.
*/
private SecureRandom createSecureRandom() {
SecureRandom result = null;
long t1 = System.currentTimeMillis();
if (secureRandomClass != null) {
try {
// Construct and seed a new random number generator
Class<?> clazz = Class.forName(secureRandomClass);
result = (SecureRandom) clazz.getConstructor().newInstance();
} catch (Exception e) {
log.error(sm.getString("sessionIdGeneratorBase.random",
secureRandomClass), e);
}
}
boolean error = false;
if (result == null) {
// No secureRandomClass or creation failed. Use SecureRandom.
try {
if (secureRandomProvider != null &&
secureRandomProvider.length() > 0) {
result = SecureRandom.getInstance(secureRandomAlgorithm,
secureRandomProvider);
} else if (secureRandomAlgorithm != null &&
secureRandomAlgorithm.length() > 0) {
result = SecureRandom.getInstance(secureRandomAlgorithm);
}
} catch (NoSuchAlgorithmException e) {
error = true;
log.error(sm.getString("sessionIdGeneratorBase.randomAlgorithm",
secureRandomAlgorithm), e);
} catch (NoSuchProviderException e) {
error = true;
log.error(sm.getString("sessionIdGeneratorBase.randomProvider",
secureRandomProvider), e);
}
}
// In theory, DEFAULT_SECURE_RANDOM_ALGORITHM should always work but
// with custom providers that might not be the case.
if (result == null && error && !DEFAULT_SECURE_RANDOM_ALGORITHM.equals(secureRandomAlgorithm)) {
// Invalid provider / algorithm - use the default
try {
result = SecureRandom.getInstance(DEFAULT_SECURE_RANDOM_ALGORITHM);
} catch (NoSuchAlgorithmException e) {
log.error(sm.getString("sessionIdGeneratorBase.randomAlgorithm",
secureRandomAlgorithm), e);
}
}
if (result == null) {
// Nothing works - use platform default
result = new SecureRandom();
}
// Force seeding to take place
result.nextInt();
long t2 = System.currentTimeMillis();
if ((t2 - t1) > 100) {
log.warn(sm.getString("sessionIdGeneratorBase.createRandom",
result.getAlgorithm(), Long.valueOf(t2 - t1)));
}
return result;
}
@Override
protected void initInternal() throws LifecycleException {
// NO-OP
}
@Override
protected void startInternal() throws LifecycleException {
// Ensure SecureRandom has been initialised
generateSessionId();
setState(LifecycleState.STARTING);
}
@Override
protected void stopInternal() throws LifecycleException {
setState(LifecycleState.STOPPING);
randoms.clear();
}
@Override
protected void destroyInternal() throws LifecycleException {
// NO-OP
}
}