/* SaslServerFactory.java
   Copyright (C) 2003, 2005, Free Software Foundation, Inc.

This file is part of GNU Classpath.

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permission to link this library with independent modules to produce an
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package javax.security.sasl;

import java.util.Map;

import javax.security.auth.callback.CallbackHandler;

/**
 * <p>An interface for creating instances of {@link SaslServer}. A class that
 * implements this interface must be thread-safe and handle multiple
 * simultaneous requests. It must also have a public constructor that accepts
 * no arguments.</p>
 *
 * <p>This interface is not normally accessed directly by a server, which will
 * use the {@link Sasl} static methods to create a {@link SaslServer} instance
 * instead. However, a particular environment may provide and install a new or
 * different <code>SaslServerFactory</code>.</p>
 *
 * @see SaslServer
 * @see Sasl
 *
 * @since 1.5
 */
public interface SaslServerFactory
{

  /**
   * Creates a {@link SaslServer} instance using the parameters supplied. It
   * returns <code>null</code> if no {@link SaslServer} instance can be created
   * using the parameters supplied. Throws {@link SaslException} if it cannot
   * create a {@link SaslServer} because of an error.
   *
   * @param mechanism the non-null IANA-registered name of a SASL mechanism
   * (e.g. "GSSAPI", "CRAM-MD5").
   * @param protocol the non-null string name of the protocol for which the
   * authentication is being performed (e.g. "ldap").
   * @param serverName the non-null fully qualified host name of the server to
   * authenticate to.
   * @param props the possibly null set of properties used to select the SASL
   * mechanism and to configure the authentication exchange of the selected
   * mechanism. See the {@link Sasl} class for a list of standard properties.
   * Other, possibly mechanism-specific, properties can be included. Properties
   * not relevant to the selected mechanism are ignored.
   * @param cbh the possibly null callback handler to used by the SASL
   * mechanisms to get further information from the application/library to
   * complete the authentication. For example, a SASL mechanism might require
   * the authentication ID, password and realm from the caller. The
   * authentication ID is requested by using a
   * {@link javax.security.auth.callback.NameCallback}. The password is
   * requested by using a {@link javax.security.auth.callback.PasswordCallback}.
   * The realm is requested by using a {@link RealmChoiceCallback} if there is
   * a list of realms to choose from, and by using a {@link RealmCallback} if
   * the realm must be entered.
   * @return a possibly null {@link SaslServer} created using the parameters
   * supplied. If <code>null</code> is returned, it means that this factory
   * cannot produce a {@link SaslServer} using the parameters supplied.
   * @throws SaslException if a SaslServer instance cannot be created because
   * of an error.
   */
  SaslServer createSaslServer(String mechanism, String protocol,
                              String serverName, Map<String, ?> props,
                              CallbackHandler cbh)
    throws SaslException;

  /**
   * Returns an array of names of mechanisms that match the specified mechanism
   * selection policies.
   *
   * @param props the possibly <code>null</code> set of properties used to
   * specify the security policy of the SASL mechanisms. For example, if props
   * contains the {@link Sasl#POLICY_NOPLAINTEXT} property with the value
   * <code>"true"</code>, then the factory must not return any SASL mechanisms
   * that are susceptible to simple plain passive attacks. See the {@link Sasl}
   * class for a complete list of policy properties. Non-policy related
   * properties, if present in props, are ignored.
   * @return a non-null array containing IANA-registered SASL mechanism names.
   */
  String[] getMechanismNames(Map<String, ?> props);
}
