001/* Sasl.java --
002   Copyright (C) 2003, 2004, 2005  Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package javax.security.sasl;
040
041import java.security.Provider;
042import java.security.Security;
043import java.util.Enumeration;
044import java.util.HashSet;
045import java.util.Iterator;
046import java.util.Map;
047import java.util.Vector;
048
049import javax.security.auth.callback.CallbackHandler;
050
051/**
052 * <p>A static class for creating SASL clients and servers.</p>
053 *
054 * <p>This class defines the policy of how to locate, load, and instantiate SASL
055 * clients and servers.</p>
056 *
057 * <p>For example, an application or library gets a SASL client instance by
058 * doing something like:</p>
059 *
060 * <pre>
061 *SaslClient sc =
062 *      Sasl.createSaslClient(mechanisms, authorizationID, protocol,
063 *                            serverName, props, callbackHandler);
064 * </pre>
065 *
066 * <p>It can then proceed to use the instance to create an authenticated
067 * connection.</p>
068 *
069 * <p>Similarly, a server gets a SASL server instance by using code that looks
070 * as follows:</p>
071 *
072 * <pre>
073 *SaslServer ss =
074 *      Sasl.createSaslServer(mechanism, protocol, serverName, props,
075 *                            callbackHandler);
076 * </pre>
077 *
078 * @since 1.5
079 */
080public class Sasl
081{
082
083  // Constants and variables
084  // -------------------------------------------------------------------------
085
086  /**
087   * <p>The name of a property that specifies the quality-of-protection to use.
088   * The property contains a comma-separated, ordered list of quality-of-
089   * protection values that the client or server is willing to support. A qop
090   * value is one of:</p>
091   *
092   * <ul>
093   *    <li><code>"auth"</code> - authentication only,</li>
094   *    <li><code>"auth-int"</code> - authentication plus integrity
095   *    protection,</li>
096   *    <li><code>"auth-conf"</code> - authentication plus integrity and
097   *    confidentiality protection.</li>
098   * </ul>
099   *
100   * <p>The order of the list specifies the preference order of the client or
101   * server.</p>
102   *
103   * <p>If this property is absent, the default qop is <code>"auth"</code>.</p>
104   *
105   * <p>The value of this constant is <code>"javax.security.sasl.qop"</code>.</p>
106   */
107  public static final String QOP = "javax.security.sasl.qop";
108
109  /**
110   * <p>The name of a property that specifies the cipher strength to use. The
111   * property contains a comma-separated, ordered list of cipher strength
112   * values that the client or server is willing to support. A strength value
113   * is one of:</p>
114   *
115   * <ul>
116   *    <li><code>"low"</code>,</li>
117   *    <li><code>"medium"</code>,</li>
118   *    <li><code>"high"</code>.</li>
119   * </ul>
120   *
121   * <p>The order of the list specifies the preference order of the client or
122   * server. An implementation should allow configuration of the meaning of
123   * these values. An application may use the Java Cryptography Extension (JCE)
124   * with JCE-aware mechanisms to control the selection of cipher suites that
125   * match the strength values.</p>
126   *
127   * <p>If this property is absent, the default strength is
128   * <code>"high,medium,low"</code>.</p>
129   *
130   * <p>The value of this constant is <code>"javax.security.sasl.strength"</code>.
131   * </p>
132   */
133  public static final String STRENGTH = "javax.security.sasl.strength";
134
135  /**
136   * <p>The name of a property that specifies whether the server must authenticate
137   * to the client. The property contains <code>"true"</code> if the server
138   * must authenticate the to client; <code>"false"</code> otherwise. The
139   * default is <code>"false"</code>.</p>
140   *
141   * <p>The value of this constant is
142   * <code>"javax.security.sasl.server.authentication"</code>.</p>
143   */
144  public static final String SERVER_AUTH = "javax.security.sasl.server.authentication";
145
146  /**
147   * <p>The name of a property that specifies the maximum size of the receive
148   * buffer in bytes of {@link SaslClient}/{@link SaslServer}. The property
149   * contains the string representation of an integer.</p>
150   *
151   * <p>If this property is absent, the default size is defined by the
152   * mechanism.</p>
153   *
154   * <p>The value of this constant is <code>"javax.security.sasl.maxbuffer"</code>.
155   * </p>
156   */
157  public static final String MAX_BUFFER = "javax.security.sasl.maxbuffer";
158
159  /**
160   * <p>The name of a property that specifies the maximum size of the raw send
161   * buffer in bytes of {@link SaslClient}/{@link SaslServer}. The property
162   * contains the string representation of an integer. The value of this
163   * property is negotiated between the client and server during the
164   * authentication exchange.</p>
165   *
166   * <p>The value of this constant is <code>"javax.security.sasl.rawsendsize"</code>.
167   * </p>
168   */
169  public static final String RAW_SEND_SIZE = "javax.security.sasl.rawsendsize";
170
171  /**
172   * <p>The name of a property that specifies whether mechanisms susceptible
173   * to simple plain passive attacks (e.g., "PLAIN") are not permitted. The
174   * property contains <code>"true"</code> if such mechanisms are not
175   * permitted; <code>"false"</code> if such mechanisms are permitted. The
176   * default is <code>"false"</code>.</p>
177   *
178   * <p>The value of this constant is <code>"javax.security.sasl.policy.noplaintext"</code>.
179   * </p>
180   */
181  public static final String POLICY_NOPLAINTEXT = "javax.security.sasl.policy.noplaintext";
182
183  /**
184   * <p>The name of a property that specifies whether mechanisms susceptible to
185   * active (non-dictionary) attacks are not permitted. The property contains
186   * <code>"true"</code> if mechanisms susceptible to active attacks are not
187   * permitted; <code>"false"</code> if such mechanisms are permitted. The
188   * default is <code>"false"</code>.</p>
189   *
190   * <p>The value of this constant is <code>"javax.security.sasl.policy.noactive"</code>.
191   * </p>
192   */
193  public static final String POLICY_NOACTIVE = "javax.security.sasl.policy.noactive";
194
195  /**
196   * <p>The name of a property that specifies whether mechanisms susceptible to
197   * passive dictionary attacks are not permitted. The property contains
198   * <code>"true"</code> if mechanisms susceptible to dictionary attacks are
199   * not permitted; <code>"false"</code> if such mechanisms are permitted. The
200   * default is <code>"false"</code>.</p>
201   *
202   * <p>The value of this constant is <code>"javax.security.sasl.policy.nodictionary"</code>.
203   * </p>
204   */
205  public static final String POLICY_NODICTIONARY = "javax.security.sasl.policy.nodictionary";
206
207  /**
208   * <p>The name of a property that specifies whether mechanisms that accept
209   * anonymous login are not permitted. The property contains <code>"true"</code>
210   * if mechanisms that accept anonymous login are not permitted; <code>"false"
211   * </code> if such mechanisms are permitted. The default is <code>"false"</code>.
212   * </p>
213   *
214   * <p>The value of this constant is <code>"javax.security.sasl.policy.noanonymous"</code>.
215   * </p>
216   */
217  public static final String POLICY_NOANONYMOUS = "javax.security.sasl.policy.noanonymous";
218
219  /**
220   * The name of a property that specifies whether mechanisms that implement
221   * forward secrecy between sessions are required. Forward secrecy means that
222   * breaking into one session will not automatically provide information for
223   * breaking into future sessions. The property contains <code>"true"</code>
224   * if mechanisms that implement forward secrecy between sessions are
225   * required; <code>"false"</code> if such mechanisms are not required. The
226   * default is <code>"false"</code>.
227   *
228   * <p>The value of this constant is <code>"javax.security.sasl.policy.forward"</code>.
229   * </p>
230   */
231  public static final String POLICY_FORWARD_SECRECY = "javax.security.sasl.policy.forward";
232
233  /**
234   * The name of a property that specifies whether mechanisms that pass client
235   * credentials are required. The property contains <code>"true"</code> if
236   * mechanisms that pass client credentials are required; <code>"false"</code>
237   * if such mechanisms are not required. The default is <code>"false"</code>.
238   *
239   * <p>The value of this constant is <code>"javax.security.sasl.policy.credentials"</code>.
240   * </p>
241   */
242  public static final String POLICY_PASS_CREDENTIALS = "javax.security.sasl.policy.credentials";
243
244  /**
245   * <p>The name of a property that specifies whether to reuse previously
246   * authenticated session information. The property contains <code>"true"</code>
247   * if the mechanism implementation may attempt to reuse previously
248   * authenticated session information; it contains <code>"false"</code> if the
249   * implementation must not reuse previously authenticated session information.
250   * A setting of <code>"true"</code> serves only as a hint; it does not
251   * necessarily entail actual reuse because reuse might not be possible due to
252   * a number of reasons, including, but not limited to, lack of mechanism
253   * support for reuse, expiration of reusable information, and the peer's
254   * refusal to support reuse. The property's default value is <code>"false"</code>.
255   * </p>
256   *
257   * <p>The value of this constant is <code>"javax.security.sasl.reuse"</code>.
258   * Note that all other parameters and properties required to create a SASL
259   * client/server instance must be provided regardless of whether this
260   * property has been supplied. That is, you cannot supply any less
261   * information in anticipation of reuse. Mechanism implementations that
262   * support reuse might allow customization of its implementation for factors
263   * such as cache size, timeouts, and criteria for reuseability. Such
264   * customizations are implementation-dependent.</p>
265   */
266  public static final String REUSE = "javax.security.sasl.reuse";
267
268  private static final String CLIENT_FACTORY_SVC = "SaslClientFactory.";
269  private static final String SERVER_FACTORY_SVC = "SaslServerFactory.";
270  private static final String ALIAS = "Alg.Alias.";
271
272  // Constructor(s)
273  // -------------------------------------------------------------------------
274
275  private Sasl()
276  {
277    super();
278  }
279
280  // Class methods
281  // -------------------------------------------------------------------------
282
283  /**
284   * Creates a {@link SaslClient} for the specified mechanism.
285   *
286   * <p>This method uses the JCA Security Provider Framework, described in the
287   * "Java Cryptography Architecture API Specification &amp; Reference", for
288   * locating and selecting a {@link SaslClient} implementation.</p>
289   *
290   * <p>First, it obtains an ordered list of {@link SaslClientFactory}
291   * instances from the registered security providers for the
292   * <code>"SaslClientFactory"</code> service and the specified mechanism. It
293   * then invokes <code>createSaslClient()</code> on each factory instance on
294   * the list until one produces a non-null {@link SaslClient} instance. It
295   * returns the non-null {@link SaslClient} instance, or <code>null</code> if
296   * the search fails to produce a non-null {@link SaslClient} instance.</p>
297   *
298   * <p>A security provider for <code>SaslClientFactory</code> registers with
299   * the JCA Security Provider Framework keys of the form:</p>
300   *
301   * <pre>
302   *    SaslClientFactory.mechanism_name
303   * </pre>
304   *
305   * <p>and values that are class names of implementations of {@link
306   * SaslClientFactory}.</p>
307   *
308   * <p>For example, a provider that contains a factory class,
309   * <code>com.wiz.sasl.digest.ClientFactory</code>, that supports the
310   * <code>"DIGEST-MD5"</code> mechanism would register the following entry
311   * with the JCA:</p>
312   *
313   * <pre>
314   *    SaslClientFactory.DIGEST-MD5     com.wiz.sasl.digest.ClientFactory
315   * </pre>
316   *
317   * <p>See the "Java Cryptography Architecture API Specification &amp;
318   * Reference" for information about how to install and configure security
319   * service providers.</p>
320   *
321   * @param mechanisms the non-null list of mechanism names to try. Each is the
322   * IANA-registered name of a SASL mechanism. (e.g. "GSSAPI", "CRAM-MD5").
323   * @param authorizationID the possibly <code>null</code> protocol-dependent
324   * identification to be used for authorization. If <code>null</code> or
325   * empty, the server derives an authorization ID from the client's
326   * authentication credentials. When the SASL authentication completes
327   * successfully, the specified entity is granted access.
328   * @param protocol the non-null string name of the protocol for which the
329   * authentication is being performed (e.g. "ldap").
330   * @param serverName the non-null fully-qualified host name of the server to
331   * authenticate to.
332   * @param props the possibly null set of properties used to select the SASL
333   * mechanism and to configure the authentication exchange of the selected
334   * mechanism. For example, if props contains the {@link Sasl#POLICY_NOPLAINTEXT}
335   * property with the value <code>"true"</code>, then the selected SASL
336   * mechanism must not be susceptible to simple plain passive attacks. In
337   * addition to the standard properties declared in this class, other,
338   * possibly mechanism-specific, properties can be included. Properties not
339   * relevant to the selected mechanism are ignored.
340   * @param cbh the possibly <code>null</code> callback handler to used by the
341   * SASL mechanisms to get further information from the application/library to
342   * complete the authentication. For example, a SASL mechanism might require
343   * the authentication ID, password and realm from the caller. The
344   * authentication ID is requested by using a
345   * {@link javax.security.auth.callback.NameCallback}. The password is
346   * requested by using a {@link javax.security.auth.callback.PasswordCallback}.
347   * The realm is requested by using a {@link RealmChoiceCallback} if there is
348   * a list of realms to choose from, and by using a {@link RealmCallback} if
349   * the realm must be entered.
350   * @return a possibly <code>null</code> {@link SaslClient} created using the
351   * parameters supplied. If <code>null</code>, the method could not find a
352   * {@link SaslClientFactory} that will produce one.
353   * @throws SaslException if a {@link SaslClient} cannot be created because
354   * of an error.
355   */
356  public static SaslClient createSaslClient(String[] mechanisms,
357                                            String authorizationID,
358                                            String protocol,
359                                            String serverName,
360                                            Map<String, ?> props,
361                                            CallbackHandler cbh)
362    throws SaslException
363  {
364    if (mechanisms == null)
365      {
366        return null;
367      }
368    Provider[] providers = Security.getProviders();
369    if (providers == null || providers.length == 0)
370      {
371        return null;
372      }
373
374    SaslClient result = null;
375    SaslClientFactory factory = null;
376    String m, clazz = null, upper, alias;
377    int j;
378    Provider p;
379    for (int i = 0; i < mechanisms.length; i++)
380      {
381        m = mechanisms[i];
382        if (m == null)
383          continue;
384        for (j = 0; j < providers.length; j++)
385          {
386            p = providers[j];
387            if (p != null)
388              {
389                // try the name as is
390                clazz = p.getProperty(CLIENT_FACTORY_SVC + m);
391                if (clazz == null) // try all uppercase
392                  {
393                    upper = m.toUpperCase();
394                    clazz = p.getProperty(CLIENT_FACTORY_SVC + upper);
395                    if (clazz == null) // try if it's an alias
396                      {
397                        alias = p.getProperty(ALIAS + CLIENT_FACTORY_SVC + m);
398                        if (alias == null) // try all-uppercase alias name
399                          {
400                            alias = p.getProperty(ALIAS + CLIENT_FACTORY_SVC + upper);
401                            if (alias == null) // spit the dummy
402                              continue;
403                          }
404                        clazz = p.getProperty(CLIENT_FACTORY_SVC + alias);
405                      }
406                  }
407                if (clazz == null)
408                  continue;
409                else
410                  clazz = clazz.trim();
411              }
412
413            try
414              {
415                result = null;
416                factory = (SaslClientFactory) Class.forName(clazz).newInstance();
417                result = factory.createSaslClient(mechanisms, authorizationID,
418                                                  protocol, serverName, props, cbh);
419              }
420            catch (ClassCastException ignored) // ignore instantiation exceptions
421              {
422              }
423            catch (ClassNotFoundException ignored)
424              {
425              }
426            catch (InstantiationException ignored)
427              {
428              }
429            catch (IllegalAccessException ignored)
430              {
431              }
432            if (result != null)
433              return result;
434          }
435      }
436    return null;
437  }
438
439  /**
440   * Gets an enumeration of known factories for producing a {@link SaslClient}
441   * instance. This method uses the same sources for locating factories as
442   * <code>createSaslClient()</code>.
443   *
444   * @return a non-null {@link Enumeration} of known factories for producing a
445   * {@link SaslClient} instance.
446   * @see #createSaslClient(String[],String,String,String,Map,CallbackHandler)
447   */
448  public static Enumeration<SaslClientFactory> getSaslClientFactories()
449  {
450    Vector result = new Vector();
451    HashSet names = new HashSet();
452    Provider[] providers = Security.getProviders();
453    Iterator it;
454    if (providers != null)
455      {
456        Provider p;
457        String key;
458        for (int i = 0; i < providers.length; i++)
459          {
460            p = providers[i];
461            for (it = p.keySet().iterator(); it.hasNext(); )
462              {
463                key = (String) it.next();
464                // add key's binding (a) it is a class of a client factory,
465                // and (b) the key does not include blanks
466                if (key.startsWith(CLIENT_FACTORY_SVC) && key.indexOf(" ") == -1)
467                  {
468                    names.add(p.getProperty(key));
469                    break;
470                  }
471              }
472          }
473      }
474    // we have the factory class names in names; instantiate and enumerate
475    String c;
476    for (it = names.iterator(); it.hasNext(); )
477      {
478        c = (String) it.next();
479        try
480          {
481            SaslClientFactory f = (SaslClientFactory) Class.forName(c).newInstance();
482            if (f != null)
483              result.add(f);
484          } catch (ClassCastException ignored) { // ignore instantiation exceptions
485          } catch (ClassNotFoundException ignored) {
486          } catch (InstantiationException ignored) {
487          } catch (IllegalAccessException ignored) {
488          }
489      }
490
491    return result.elements();
492  }
493
494  /**
495   * Creates a {@link SaslServer} for the specified mechanism.
496   *
497   * <p>This method uses the JCA Security Provider Framework, described in the
498   * "Java Cryptography Architecture API Specification &amp; Reference", for
499   * locating and selecting a SaslServer implementation.</p>
500   *
501   * <p>First, it obtains an ordered list of {@link SaslServerFactory}
502   * instances from the registered security providers for the
503   * <code>"SaslServerFactory"</code> service and the specified mechanism. It
504   * then invokes <code>createSaslServer()</code> on each factory instance on
505   * the list until one produces a non-null {@link SaslServer} instance. It
506   * returns the non-null {@link SaslServer} instance, or <code>null</code> if
507   * the search fails to produce a non-null {@link SaslServer} instance.</p>
508   *
509   * <p>A security provider for {@link SaslServerFactory} registers with the
510   * JCA Security Provider Framework keys of the form:</p>
511   *
512   * <pre>
513   *    SaslServerFactory.mechanism_name
514   * </pre>
515   *
516   * <p>and values that are class names of implementations of {@link
517   * SaslServerFactory}.</p>
518   *
519   * <p>For example, a provider that contains a factory class,
520   * <code>com.wiz.sasl.digest.ServerFactory</code>, that supports the
521   * <code>"DIGEST-MD5"</code> mechanism would register the following entry
522   * with the JCA:</p>
523   *
524   * <pre>
525   *    SaslServerFactory.DIGEST-MD5     com.wiz.sasl.digest.ServerFactory
526   * </pre>
527   *
528   * <p>See the "Java Cryptography Architecture API Specification &amp;
529   * Reference" for information about how to install and configure security
530   * service providers.</p>
531   *
532   * @param mechanism the non-null mechanism name. It must be an
533   * IANA-registered name of a SASL mechanism. (e.g. "GSSAPI", "CRAM-MD5").
534   * @param protocol the non-null string name of the protocol for which the
535   * authentication is being performed (e.g. "ldap").
536   * @param serverName the non-null fully qualified host name of the server.
537   * @param props the possibly <code>null</code> set of properties used to
538   * select the SASL mechanism and to configure the authentication exchange of
539   * the selected mechanism. For example, if props contains the {@link
540   * Sasl#POLICY_NOPLAINTEXT} property with the value <code>"true"</code>, then
541   * the selected SASL mechanism must not be susceptible to simple plain
542   * passive attacks. In addition to the standard properties declared in this
543   * class, other, possibly mechanism-specific, properties can be included.
544   * Properties not relevant to the selected mechanism are ignored.
545   * @param cbh the possibly <code>null</code> callback handler to used by the
546   * SASL mechanisms to get further information from the application/library to
547   * complete the authentication. For example, a SASL mechanism might require
548   * the authentication ID, password and realm from the caller. The
549   * authentication ID is requested by using a
550   * {@link javax.security.auth.callback.NameCallback}. The password is
551   * requested by using a {@link javax.security.auth.callback.PasswordCallback}.
552   * The realm is requested by using a {@link RealmChoiceCallback} if there is
553   * a list of realms to choose from, and by using a {@link RealmCallback} if
554   * the realm must be entered.
555   * @return a possibly <code>null</code> {@link SaslServer} created using the
556   * parameters supplied. If <code>null</code>, the method cannot find a
557   * {@link SaslServerFactory} instance that will produce one.
558   * @throws SaslException if a {@link SaslServer} instance cannot be created
559   * because of an error.
560   */
561  public static SaslServer createSaslServer(String mechanism, String protocol,
562                                            String serverName,
563                                            Map<String, ?> props,
564                                            CallbackHandler cbh)
565    throws SaslException
566  {
567    if (mechanism == null)
568      return null;
569    Provider[] providers = Security.getProviders();
570    if (providers == null || providers.length == 0)
571      return null;
572
573    SaslServer result = null;
574    SaslServerFactory factory = null;
575    String clazz = null, upper, alias = null;
576    int j;
577    Provider p;
578    for (j = 0; j < providers.length; j++)
579      {
580        p = providers[j];
581        if (p != null)
582          {
583            // try the name as is
584            clazz = p.getProperty(SERVER_FACTORY_SVC + mechanism);
585            if (clazz == null) // try all uppercase
586              {
587                upper = mechanism.toUpperCase();
588                clazz = p.getProperty(SERVER_FACTORY_SVC + upper);
589                if (clazz == null) // try if it's an alias
590                  {
591                    alias = p.getProperty(ALIAS + SERVER_FACTORY_SVC + mechanism);
592                    if (alias == null) // try all-uppercase alias name
593                      {
594                        alias = p.getProperty(ALIAS + SERVER_FACTORY_SVC + upper);
595                        if (alias == null) // spit the dummy
596                          continue;
597                      }
598                  }
599                clazz = p.getProperty(SERVER_FACTORY_SVC + alias);
600              }
601          }
602        if (clazz == null)
603          continue;
604        else
605          clazz = clazz.trim();
606
607        try
608          {
609            result = null;
610            factory = (SaslServerFactory) Class.forName(clazz).newInstance();
611            result =
612              factory.createSaslServer(mechanism, protocol, serverName, props, cbh);
613          }
614        catch (ClassCastException ignored) // ignore instantiation exceptions
615          {
616          }
617        catch (ClassNotFoundException ignored)
618          {
619          }
620        catch (InstantiationException ignored)
621          {
622          }
623        catch (IllegalAccessException ignored)
624          {
625          }
626        if (result != null)
627          return result;
628      }
629    return null;
630  }
631
632  /**
633   * Gets an enumeration of known factories for producing a {@link SaslServer}
634   * instance. This method uses the same sources for locating factories as
635   * <code>createSaslServer()</code>.
636   *
637   * @return a non-null {@link Enumeration} of known factories for producing a
638   * {@link SaslServer} instance.
639   * @see #createSaslServer(String,String,String,Map,CallbackHandler)
640   */
641  public static Enumeration<SaslServerFactory> getSaslServerFactories()
642  {
643    Vector result = new Vector();
644    HashSet names = new HashSet();
645    Provider[] providers = Security.getProviders();
646    Iterator it;
647    if (providers != null)
648      {
649        Provider p;
650        String key;
651        for (int i = 0; i < providers.length; i++)
652          {
653            p = providers[i];
654            for (it = p.keySet().iterator(); it.hasNext(); )
655              {
656                key = (String) it.next();
657                // add key's binding (a) it is a class of a server factory,
658                // and (b) the key does not include blanks
659                if (key.startsWith(SERVER_FACTORY_SVC) && key.indexOf(" ") == -1)
660                  {
661                    names.add(p.getProperty(key));
662                    break;
663                  }
664              }
665          }
666      }
667    // we have the factory class names in names; instantiate and enumerate
668    String c;
669    for (it = names.iterator(); it.hasNext(); )
670      {
671        c = (String) it.next();
672        try
673          {
674            SaslServerFactory f = (SaslServerFactory) Class.forName(c).newInstance();
675            if (f != null)
676              result.add(f);
677          }
678        catch (ClassCastException ignored) // ignore instantiation exceptions
679          {
680          }
681        catch (ClassNotFoundException ignored)
682          {
683          }
684        catch (InstantiationException ignored)
685          {
686          }
687        catch (IllegalAccessException ignored)
688          {
689          }
690      }
691
692    return result.elements();
693  }
694}