JDK8/Java8源码在线阅读
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package java.security;
import java.lang.reflect.*;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import java.io.*;
import java.net.URL;
import sun.security.util.Debug;
import sun.security.util.PropertyExpander;
import sun.security.jca.*;
/**
* <p>This class centralizes all security properties and common security
* methods. One of its primary uses is to manage providers.
*
* <p>The default values of security properties are read from an
* implementation-specific location, which is typically the properties file
* {@code lib/security/java.security} in the Java installation directory.
*
* @author Benjamin Renaud
*/
public final class Security {
/* Are we debugging? -- for developers */
private static final Debug sdebug =
Debug.getInstance("properties");
/* The java.security properties */
private static Properties props;
// An element in the cache
private static class ProviderProperty {
String className;
Provider provider;
}
static {
// doPrivileged here because there are multiple
// things in initialize that might require privs.
// (the FileInputStream call and the File.exists call,
// the securityPropFile call, etc)
AccessController.doPrivileged(new PrivilegedAction<Void>() {
public Void run() {
initialize();
return null;
}
});
}
private static void initialize() {
props = new Properties();
boolean loadedProps = false;
boolean overrideAll = false;
// first load the system properties file
// to determine the value of security.overridePropertiesFile
File propFile = securityPropFile("java.security");
if (propFile.exists()) {
InputStream is = null;
try {
FileInputStream fis = new FileInputStream(propFile);
is = new BufferedInputStream(fis);
props.load(is);
loadedProps = true;
if (sdebug != null) {
sdebug.println("reading security properties file: " +
propFile);
}
} catch (IOException e) {
if (sdebug != null) {
sdebug.println("unable to load security properties from " +
propFile);
e.printStackTrace();
}
} finally {
if (is != null) {
try {
is.close();
} catch (IOException ioe) {
if (sdebug != null) {
sdebug.println("unable to close input stream");
}
}
}
}
}
if ("true".equalsIgnoreCase(props.getProperty
("security.overridePropertiesFile"))) {
String extraPropFile = System.getProperty
("java.security.properties");
if (extraPropFile != null && extraPropFile.startsWith("=")) {
overrideAll = true;
extraPropFile = extraPropFile.substring(1);
}
if (overrideAll) {
props = new Properties();
if (sdebug != null) {
sdebug.println
("overriding other security properties files!");
}
}
// now load the user-specified file so its values
// will win if they conflict with the earlier values
if (extraPropFile != null) {
BufferedInputStream bis = null;
try {
URL propURL;
extraPropFile = PropertyExpander.expand(extraPropFile);
propFile = new File(extraPropFile);
if (propFile.exists()) {
propURL = new URL
("file:" + propFile.getCanonicalPath());
} else {
propURL = new URL(extraPropFile);
}
bis = new BufferedInputStream(propURL.openStream());
props.load(bis);
loadedProps = true;
if (sdebug != null) {
sdebug.println("reading security properties file: " +
propURL);
if (overrideAll) {
sdebug.println
("overriding other security properties files!");
}
}
} catch (Exception e) {
if (sdebug != null) {
sdebug.println
("unable to load security properties from " +
extraPropFile);
e.printStackTrace();
}
} finally {
if (bis != null) {
try {
bis.close();
} catch (IOException ioe) {
if (sdebug != null) {
sdebug.println("unable to close input stream");
}
}
}
}
}
}
if (!loadedProps) {
initializeStatic();
if (sdebug != null) {
sdebug.println("unable to load security properties " +
"-- using defaults");
}
}
}
/*
* Initialize to default values, if <java.home>/lib/java.security
* is not found.
*/
private static void initializeStatic() {
props.put("security.provider.1", "sun.security.provider.Sun");
props.put("security.provider.2", "sun.security.rsa.SunRsaSign");
props.put("security.provider.3", "com.sun.net.ssl.internal.ssl.Provider");
props.put("security.provider.4", "com.sun.crypto.provider.SunJCE");
props.put("security.provider.5", "sun.security.jgss.SunProvider");
props.put("security.provider.6", "com.sun.security.sasl.Provider");
}
/**
* Don't let anyone instantiate this.
*/
private Security() {
}
private static File securityPropFile(String filename) {
// maybe check for a system property which will specify where to
// look. Someday.
String sep = File.separator;
return new File(System.getProperty("java.home") + sep + "lib" + sep +
"security" + sep + filename);
}
/**
* Looks up providers, and returns the property (and its associated
* provider) mapping the key, if any.
* The order in which the providers are looked up is the
* provider-preference order, as specificed in the security
* properties file.
*/
private static ProviderProperty getProviderProperty(String key) {
ProviderProperty entry = null;
List<Provider> providers = Providers.getProviderList().providers();
for (int i = 0; i < providers.size(); i++) {
String matchKey = null;
Provider prov = providers.get(i);
String prop = prov.getProperty(key);
if (prop == null) {
// Is there a match if we do a case-insensitive property name
// comparison? Let's try ...
for (Enumeration<Object> e = prov.keys();
e.hasMoreElements() && prop == null; ) {
matchKey = (String)e.nextElement();
if (key.equalsIgnoreCase(matchKey)) {
prop = prov.getProperty(matchKey);
break;
}
}
}
if (prop != null) {
ProviderProperty newEntry = new ProviderProperty();
newEntry.className = prop;
newEntry.provider = prov;
return newEntry;
}
}
return entry;
}
/**
* Returns the property (if any) mapping the key for the given provider.
*/
private static String getProviderProperty(String key, Provider provider) {
String prop = provider.getProperty(key);
if (prop == null) {
// Is there a match if we do a case-insensitive property name
// comparison? Let's try ...
for (Enumeration<Object> e = provider.keys();
e.hasMoreElements() && prop == null; ) {
String matchKey = (String)e.nextElement();
if (key.equalsIgnoreCase(matchKey)) {
prop = provider.getProperty(matchKey);
break;
}
}
}
return prop;
}
/**
* Gets a specified property for an algorithm. The algorithm name
* should be a standard name. See the <a href=
* "{@docRoot}/../technotes/guides/security/StandardNames.html">
* Java Cryptography Architecture Standard Algorithm Name Documentation</a>
* for information about standard algorithm names.
*
* One possible use is by specialized algorithm parsers, which may map
* classes to algorithms which they understand (much like Key parsers
* do).
*
* @param algName the algorithm name.
*
* @param propName the name of the property to get.
*
* @return the value of the specified property.
*
* @deprecated This method used to return the value of a proprietary
* property in the master file of the "SUN" Cryptographic Service
* Provider in order to determine how to parse algorithm-specific
* parameters. Use the new provider-based and algorithm-independent
* {@code AlgorithmParameters} and {@code KeyFactory} engine
* classes (introduced in the J2SE version 1.2 platform) instead.
*/
@Deprecated
public static String getAlgorithmProperty(String algName,
String propName) {
ProviderProperty entry = getProviderProperty("Alg." + propName
+ "." + algName);
if (entry != null) {
return entry.className;
} else {
return null;
}
}
/**
* Adds a new provider, at a specified position. The position is
* the preference order in which providers are searched for
* requested algorithms. The position is 1-based, that is,
* 1 is most preferred, followed by 2, and so on.
*
* <p>If the given provider is installed at the requested position,
* the provider that used to be at that position, and all providers
* with a position greater than {@code position}, are shifted up
* one position (towards the end of the list of installed providers).
*
* <p>A provider cannot be added if it is already installed.
*
* <p>If there is a security manager, the
* {@link java.lang.SecurityManager#checkSecurityAccess} method is called
* with the {@code "insertProvider"} permission target name to see if
* it's ok to add a new provider. If this permission check is denied,
* {@code checkSecurityAccess} is called again with the
* {@code "insertProvider."+provider.getName()} permission target name. If
* both checks are denied, a {@code SecurityException} is thrown.
*
* @param provider the provider to be added.
*
* @param position the preference position that the caller would
* like for this provider.
*
* @return the actual preference position in which the provider was
* added, or -1 if the provider was not added because it is
* already installed.
*
* @throws NullPointerException if provider is null
* @throws SecurityException
* if a security manager exists and its {@link
* java.lang.SecurityManager#checkSecurityAccess} method
* denies access to add a new provider
*
* @see #getProvider
* @see #removeProvider
* @see java.security.SecurityPermission
*/
public static synchronized int insertProviderAt(Provider provider,
int position) {
String providerName = provider.getName();
checkInsertProvider(providerName);
ProviderList list = Providers.getFullProviderList();
ProviderList newList = ProviderList.insertAt(list, provider, position - 1);
if (list == newList) {
return -1;
}
Providers.setProviderList(newList);
return newList.getIndex(providerName) + 1;
}
/**
* Adds a provider to the next position available.
*
* <p>If there is a security manager, the
* {@link java.lang.SecurityManager#checkSecurityAccess} method is called
* with the {@code "insertProvider"} permission target name to see if
* it's ok to add a new provider. If this permission check is denied,
* {@code checkSecurityAccess} is called again with the
* {@code "insertProvider."+provider.getName()} permission target name. If
* both checks are denied, a {@code SecurityException} is thrown.
*
* @param provider the provider to be added.
*
* @return the preference position in which the provider was
* added, or -1 if the provider was not added because it is
* already installed.
*
* @throws NullPointerException if provider is null
* @throws SecurityException
* if a security manager exists and its {@link
* java.lang.SecurityManager#checkSecurityAccess} method
* denies access to add a new provider
*
* @see #getProvider
* @see #removeProvider
* @see java.security.SecurityPermission
*/
public static int addProvider(Provider provider) {
/*
* We can't assign a position here because the statically
* registered providers may not have been installed yet.
* insertProviderAt() will fix that value after it has
* loaded the static providers.
*/
return insertProviderAt(provider, 0);
}
/**
* Removes the provider with the specified name.
*
* <p>When the specified provider is removed, all providers located
* at a position greater than where the specified provider was are shifted
* down one position (towards the head of the list of installed
* providers).
*
* <p>This method returns silently if the provider is not installed or
* if name is null.
*
* <p>First, if there is a security manager, its
* {@code checkSecurityAccess}
* method is called with the string {@code "removeProvider."+name}
* to see if it's ok to remove the provider.
* If the default implementation of {@code checkSecurityAccess}
* is used (i.e., that method is not overriden), then this will result in
* a call to the security manager's {@code checkPermission} method
* with a {@code SecurityPermission("removeProvider."+name)}
* permission.
*
* @param name the name of the provider to remove.
*
* @throws SecurityException
* if a security manager exists and its {@link
* java.lang.SecurityManager#checkSecurityAccess} method
* denies
* access to remove the provider
*
* @see #getProvider
* @see #addProvider
*/
public static synchronized void removeProvider(String name) {
check("removeProvider." + name);
ProviderList list = Providers.getFullProviderList();
ProviderList newList = ProviderList.remove(list, name);
Providers.setProviderList(newList);
}
/**
* Returns an array containing all the installed providers. The order of
* the providers in the array is their preference order.
*
* @return an array of all the installed providers.
*/
public static Provider[] getProviders() {
return Providers.getFullProviderList().toArray();
}
/**
* Returns the provider installed with the specified name, if
* any. Returns null if no provider with the specified name is
* installed or if name is null.
*
* @param name the name of the provider to get.
*
* @return the provider of the specified name.
*
* @see #removeProvider
* @see #addProvider
*/
public static Provider getProvider(String name) {
return Providers.getProviderList().getProvider(name);
}
/**
* Returns an array containing all installed providers that satisfy the
* specified selection criterion, or null if no such providers have been
* installed. The returned providers are ordered
* according to their
* {@linkplain #insertProviderAt(java.security.Provider, int) preference order}.
*
* <p> A cryptographic service is always associated with a particular
* algorithm or type. For example, a digital signature service is
* always associated with a particular algorithm (e.g., DSA),
* and a CertificateFactory service is always associated with
* a particular certificate type (e.g., X.509).
*
* <p>The selection criterion must be specified in one of the following two
* formats:
* <ul>
* <li> <i>{@literal <crypto_service>.<algorithm_or_type>}</i>
* <p> The cryptographic service name must not contain any dots.
* <p> A
* provider satisfies the specified selection criterion iff the provider
* implements the
* specified algorithm or type for the specified cryptographic service.
* <p> For example, "CertificateFactory.X.509"
* would be satisfied by any provider that supplied
* a CertificateFactory implementation for X.509 certificates.
* <li> <i>{@literal <crypto_service>.<algorithm_or_type>
* <attribute_name>:<attribute_value>}</i>
* <p> The cryptographic service name must not contain any dots. There
* must be one or more space characters between the
* <i>{@literal <algorithm_or_type>}</i> and the
* <i>{@literal <attribute_name>}</i>.
* <p> A provider satisfies this selection criterion iff the
* provider implements the specified algorithm or type for the specified
* cryptographic service and its implementation meets the
* constraint expressed by the specified attribute name/value pair.
* <p> For example, "Signature.SHA1withDSA KeySize:1024" would be
* satisfied by any provider that implemented
* the SHA1withDSA signature algorithm with a keysize of 1024 (or larger).
*
* </ul>
*
* <p> See the <a href=
* "{@docRoot}/../technotes/guides/security/StandardNames.html">
* Java Cryptography Architecture Standard Algorithm Name Documentation</a>
* for information about standard cryptographic service names, standard
* algorithm names and standard attribute names.
*
* @param filter the criterion for selecting
* providers. The filter is case-insensitive.
*
* @return all the installed providers that satisfy the selection
* criterion, or null if no such providers have been installed.
*
* @throws InvalidParameterException
* if the filter is not in the required format
* @throws NullPointerException if filter is null
*
* @see #getProviders(java.util.Map)
* @since 1.3
*/
public static Provider[] getProviders(String filter) {
String key = null;
String value = null;
int index = filter.indexOf(':');
if (index == -1) {
key = filter;
value = "";
} else {
key = filter.substring(0, index);
value = filter.substring(index + 1);
}
Hashtable<String, String> hashtableFilter = new Hashtable<>(1);
hashtableFilter.put(key, value);
return (getProviders(hashtableFilter));
}
/**
* Returns an array containing all installed providers that satisfy the
* specified* selection criteria, or null if no such providers have been
* installed. The returned providers are ordered
* according to their
* {@linkplain #insertProviderAt(java.security.Provider, int)
* preference order}.
*
* <p>The selection criteria are represented by a map.
* Each map entry represents a selection criterion.
* A provider is selected iff it satisfies all selection
* criteria. The key for any entry in such a map must be in one of the
* following two formats:
* <ul>
* <li> <i>{@literal <crypto_service>.<algorithm_or_type>}</i>
* <p> The cryptographic service name must not contain any dots.
* <p> The value associated with the key must be an empty string.
* <p> A provider
* satisfies this selection criterion iff the provider implements the
* specified algorithm or type for the specified cryptographic service.
* <li> <i>{@literal <crypto_service>}.
* {@literal <algorithm_or_type> <attribute_name>}</i>
* <p> The cryptographic service name must not contain any dots. There
* must be one or more space characters between the
* <i>{@literal <algorithm_or_type>}</i>
* and the <i>{@literal <attribute_name>}</i>.
* <p> The value associated with the key must be a non-empty string.
* A provider satisfies this selection criterion iff the
* provider implements the specified algorithm or type for the specified
* cryptographic service and its implementation meets the
* constraint expressed by the specified attribute name/value pair.
* </ul>
*
* <p> See the <a href=
* "../../../technotes/guides/security/StandardNames.html">
* Java Cryptography Architecture Standard Algorithm Name Documentation</a>
* for information about standard cryptographic service names, standard
* algorithm names and standard attribute names.
*
* @param filter the criteria for selecting
* providers. The filter is case-insensitive.
*
* @return all the installed providers that satisfy the selection
* criteria, or null if no such providers have been installed.
*
* @throws InvalidParameterException
* if the filter is not in the required format
* @throws NullPointerException if filter is null
*
* @see #getProviders(java.lang.String)
* @since 1.3
*/
public static Provider[] getProviders(Map<String,String> filter) {
// Get all installed providers first.
// Then only return those providers who satisfy the selection criteria.
Provider[] allProviders = Security.getProviders();
Set<String> keySet = filter.keySet();
LinkedHashSet<Provider> candidates = new LinkedHashSet<>(5);
// Returns all installed providers
// if the selection criteria is null.
if ((keySet == null) || (allProviders == null)) {
return allProviders;
}
boolean firstSearch = true;
// For each selection criterion, remove providers
// which don't satisfy the criterion from the candidate set.
for (Iterator<String> ite = keySet.iterator(); ite.hasNext(); ) {
String key = ite.next();
String value = filter.get(key);
LinkedHashSet<Provider> newCandidates = getAllQualifyingCandidates(key, value,
allProviders);
if (firstSearch) {
candidates = newCandidates;
firstSearch = false;
}
if ((newCandidates != null) && !newCandidates.isEmpty()) {
// For each provider in the candidates set, if it
// isn't in the newCandidate set, we should remove
// it from the candidate set.
for (Iterator<Provider> cansIte = candidates.iterator();
cansIte.hasNext(); ) {
Provider prov = cansIte.next();
if (!newCandidates.contains(prov)) {
cansIte.remove();
}
}
} else {
candidates = null;
break;
}
}
if ((candidates == null) || (candidates.isEmpty()))
return null;
Object[] candidatesArray = candidates.toArray();
Provider[] result = new Provider[candidatesArray.length];
for (int i = 0; i < result.length; i++) {
result[i] = (Provider)candidatesArray[i];
}
return result;
}
// Map containing cached Spi Class objects of the specified type
private static final Map<String, Class<?>> spiMap =
new ConcurrentHashMap<>();
/**
* Return the Class object for the given engine type
* (e.g. "MessageDigest"). Works for Spis in the java.security package
* only.
*/
private static Class<?> getSpiClass(String type) {
Class<?> clazz = spiMap.get(type);
if (clazz != null) {
return clazz;
}
try {
clazz = Class.forName("java.security." + type + "Spi");
spiMap.put(type, clazz);
return clazz;
} catch (ClassNotFoundException e) {
throw new AssertionError("Spi class not found", e);
}
}
/*
* Returns an array of objects: the first object in the array is
* an instance of an implementation of the requested algorithm
* and type, and the second object in the array identifies the provider
* of that implementation.
* The {@code provider} argument can be null, in which case all
* configured providers will be searched in order of preference.
*/
static Object[] getImpl(String algorithm, String type, String provider)
throws NoSuchAlgorithmException, NoSuchProviderException {
if (provider == null) {
return GetInstance.getInstance
(type, getSpiClass(type), algorithm).toArray();
} else {
return GetInstance.getInstance
(type, getSpiClass(type), algorithm, provider).toArray();
}
}
static Object[] getImpl(String algorithm, String type, String provider,
Object params) throws NoSuchAlgorithmException,
NoSuchProviderException, InvalidAlgorithmParameterException {
if (provider == null) {
return GetInstance.getInstance
(type, getSpiClass(type), algorithm, params).toArray();
} else {
return GetInstance.getInstance
(type, getSpiClass(type), algorithm, params, provider).toArray();
}
}
/*
* Returns an array of objects: the first object in the array is
* an instance of an implementation of the requested algorithm
* and type, and the second object in the array identifies the provider
* of that implementation.
* The {@code provider} argument cannot be null.
*/
static Object[] getImpl(String algorithm, String type, Provider provider)
throws NoSuchAlgorithmException {
return GetInstance.getInstance
(type, getSpiClass(type), algorithm, provider).toArray();
}
static Object[] getImpl(String algorithm, String type, Provider provider,
Object params) throws NoSuchAlgorithmException,
InvalidAlgorithmParameterException {
return GetInstance.getInstance
(type, getSpiClass(type), algorithm, params, provider).toArray();
}
/**
* Gets a security property value.
*
* <p>First, if there is a security manager, its
* {@code checkPermission} method is called with a
* {@code java.security.SecurityPermission("getProperty."+key)}
* permission to see if it's ok to retrieve the specified
* security property value..
*
* @param key the key of the property being retrieved.
*
* @return the value of the security property corresponding to key.
*
* @throws SecurityException
* if a security manager exists and its {@link
* java.lang.SecurityManager#checkPermission} method
* denies
* access to retrieve the specified security property value
* @throws NullPointerException is key is null
*
* @see #setProperty
* @see java.security.SecurityPermission
*/
public static String getProperty(String key) {
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
sm.checkPermission(new SecurityPermission("getProperty."+
key));
}
String name = props.getProperty(key);
if (name != null)
name = name.trim(); // could be a class name with trailing ws
return name;
}
/**
* Sets a security property value.
*
* <p>First, if there is a security manager, its
* {@code checkPermission} method is called with a
* {@code java.security.SecurityPermission("setProperty."+key)}
* permission to see if it's ok to set the specified
* security property value.
*
* @param key the name of the property to be set.
*
* @param datum the value of the property to be set.
*
* @throws SecurityException
* if a security manager exists and its {@link
* java.lang.SecurityManager#checkPermission} method
* denies access to set the specified security property value
* @throws NullPointerException if key or datum is null
*
* @see #getProperty
* @see java.security.SecurityPermission
*/
public static void setProperty(String key, String datum) {
check("setProperty."+key);
props.put(key, datum);
invalidateSMCache(key); /* See below. */
}
/*
* Implementation detail: If the property we just set in
* setProperty() was either "package.access" or
* "package.definition", we need to signal to the SecurityManager
* class that the value has just changed, and that it should
* invalidate it's local cache values.
*
* Rather than create a new API entry for this function,
* we use reflection to set a private variable.
*/
private static void invalidateSMCache(String key) {
final boolean pa = key.equals("package.access");
final boolean pd = key.equals("package.definition");
if (pa || pd) {
AccessController.doPrivileged(new PrivilegedAction<Void>() {
public Void run() {
try {
/* Get the class via the bootstrap class loader. */
Class<?> cl = Class.forName(
"java.lang.SecurityManager", false, null);
Field f = null;
boolean accessible = false;
if (pa) {
f = cl.getDeclaredField("packageAccessValid");
accessible = f.isAccessible();
f.setAccessible(true);
} else {
f = cl.getDeclaredField("packageDefinitionValid");
accessible = f.isAccessible();
f.setAccessible(true);
}
f.setBoolean(f, false);
f.setAccessible(accessible);
}
catch (Exception e1) {
/* If we couldn't get the class, it hasn't
* been loaded yet. If there is no such
* field, we shouldn't try to set it. There
* shouldn't be a security execption, as we
* are loaded by boot class loader, and we
* are inside a doPrivileged() here.
*
* NOOP: don't do anything...
*/
}
return null;
} /* run */
}); /* PrivilegedAction */
} /* if */
}
private static void check(String directive) {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkSecurityAccess(directive);
}
}
private static void checkInsertProvider(String name) {
SecurityManager security = System.getSecurityManager();
if (security != null) {
try {
security.checkSecurityAccess("insertProvider");
} catch (SecurityException se1) {
try {
security.checkSecurityAccess("insertProvider." + name);
} catch (SecurityException se2) {
// throw first exception, but add second to suppressed
se1.addSuppressed(se2);
throw se1;
}
}
}
}
/*
* Returns all providers who satisfy the specified
* criterion.
*/
private static LinkedHashSet<Provider> getAllQualifyingCandidates(
String filterKey,
String filterValue,
Provider[] allProviders) {
String[] filterComponents = getFilterComponents(filterKey,
filterValue);
// The first component is the service name.
// The second is the algorithm name.
// If the third isn't null, that is the attrinute name.
String serviceName = filterComponents[0];
String algName = filterComponents[1];
String attrName = filterComponents[2];
return getProvidersNotUsingCache(serviceName, algName, attrName,
filterValue, allProviders);
}
private static LinkedHashSet<Provider> getProvidersNotUsingCache(
String serviceName,
String algName,
String attrName,
String filterValue,
Provider[] allProviders) {
LinkedHashSet<Provider> candidates = new LinkedHashSet<>(5);
for (int i = 0; i < allProviders.length; i++) {
if (isCriterionSatisfied(allProviders[i], serviceName,
algName,
attrName, filterValue)) {
candidates.add(allProviders[i]);
}
}
return candidates;
}
/*
* Returns true if the given provider satisfies
* the selection criterion key:value.
*/
private static boolean isCriterionSatisfied(Provider prov,
String serviceName,
String algName,
String attrName,
String filterValue) {
String key = serviceName + '.' + algName;
if (attrName != null) {
key += ' ' + attrName;
}
// Check whether the provider has a property
// whose key is the same as the given key.
String propValue = getProviderProperty(key, prov);
if (propValue == null) {
// Check whether we have an alias instead
// of a standard name in the key.
String standardName = getProviderProperty("Alg.Alias." +
serviceName + "." +
algName,
prov);
if (standardName != null) {
key = serviceName + "." + standardName;
if (attrName != null) {
key += ' ' + attrName;
}
propValue = getProviderProperty(key, prov);
}
if (propValue == null) {
// The provider doesn't have the given
// key in its property list.
return false;
}
}
// If the key is in the format of:
// <crypto_service>.<algorithm_or_type>,
// there is no need to check the value.
if (attrName == null) {
return true;
}
// If we get here, the key must be in the
// format of <crypto_service>.<algorithm_or_provider> <attribute_name>.
if (isStandardAttr(attrName)) {
return isConstraintSatisfied(attrName, filterValue, propValue);
} else {
return filterValue.equalsIgnoreCase(propValue);
}
}
/*
* Returns true if the attribute is a standard attribute;
* otherwise, returns false.
*/
private static boolean isStandardAttr(String attribute) {
// For now, we just have two standard attributes:
// KeySize and ImplementedIn.
if (attribute.equalsIgnoreCase("KeySize"))
return true;
if (attribute.equalsIgnoreCase("ImplementedIn"))
return true;
return false;
}
/*
* Returns true if the requested attribute value is supported;
* otherwise, returns false.
*/
private static boolean isConstraintSatisfied(String attribute,
String value,
String prop) {
// For KeySize, prop is the max key size the
// provider supports for a specific <crypto_service>.<algorithm>.
if (attribute.equalsIgnoreCase("KeySize")) {
int requestedSize = Integer.parseInt(value);
int maxSize = Integer.parseInt(prop);
if (requestedSize <= maxSize) {
return true;
} else {
return false;
}
}
// For Type, prop is the type of the implementation
// for a specific <crypto service>.<algorithm>.
if (attribute.equalsIgnoreCase("ImplementedIn")) {
return value.equalsIgnoreCase(prop);
}
return false;
}
static String[] getFilterComponents(String filterKey, String filterValue) {
int algIndex = filterKey.indexOf('.');
if (algIndex < 0) {
// There must be a dot in the filter, and the dot
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