/* SasServer.java
Copyright (C) 2003, Free Software Foundation, Inc.
This file is part of GNU Classpath.
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package javax.security.sasl;
/**
* <p>Performs SASL authentication as a server.</p>
*
* <p>A server such as an LDAP server gets an instance of this class in order to
* perform authentication defined by a specific SASL mechanism. Invoking methods
* on the <code>SaslServer</code> instance generates challenges corresponding to
* the SASL mechanism implemented by the <code>SaslServer</code> instance. As
* the authentication proceeds, the instance encapsulates the state of a SASL
* server's authentication exchange.</p>
*
* <p>Here's an example of how an LDAP server might use a <code>SaslServer</code>
* instance. It first gets an instance of a <code>SaslServer</code> for the SASL
* mechanism requested by the client:</p>
*
* <pre>
*SaslServer ss =
* Sasl.createSaslServer(mechanism, "ldap", myFQDN, props, callbackHandler);
* </pre>
*
* <p>It can then proceed to use the server for authentication. For example,
* suppose the LDAP server received an LDAP BIND request containing the name of
* the SASL mechanism and an (optional) initial response. It then might use the
* server as follows:</p>
*
* <pre>
*while (!ss.isComplete()) {
* try {
* byte[] challenge = ss.evaluateResponse(response);
* if (ss.isComplete()) {
* status = ldap.sendBindResponse(mechanism, challenge, SUCCESS);
* } else {
* status = ldap.sendBindResponse(mechanism, challenge, SASL_BIND_IN_PROGRESS);
* response = ldap.readBindRequest();
* }
* } catch (SaslException x) {
* status = ldap.sendErrorResponse(x);
* break;
* }
*}
*if (ss.isComplete() && (status == SUCCESS)) {
* String qop = (String) sc.getNegotiatedProperty(Sasl.QOP);
* if (qop != null
* && (qop.equalsIgnoreCase("auth-int")
* || qop.equalsIgnoreCase("auth-conf"))) {
* // Use SaslServer.wrap() and SaslServer.unwrap() for future
* // communication with client
* ldap.in = new SecureInputStream(ss, ldap.in);
* ldap.out = new SecureOutputStream(ss, ldap.out);
* }
*}
* </pre>
*
* @see Sasl
* @see SaslServerFactory
*/
public interface SaslServer
{
/**
* Returns the IANA-registered mechanism name of this SASL server (e.g.
* "CRAM-MD5", "GSSAPI").
*
* @return a non-null string representing the IANA-registered mechanism name.
*/
String getMechanismName();
/**
* Evaluates the response data and generates a challenge. If a response is
* received from the client during the authentication process, this method is
* called to prepare an appropriate next challenge to submit to the client.
* The challenge is <code>null</code> if the authentication has succeeded and
* no more challenge data is to be sent to the client. It is non-null if the
* authentication must be continued by sending a challenge to the client, or
* if the authentication has succeeded but challenge data needs to be
* processed by the client. {@link #isComplete()} should be called after each
* call to <code>evaluateResponse()</code>,to determine if any further
* response is needed from the client.
*
* @param response the non-null (but possibly empty) response sent by the
* client.
* @return the possibly <code>null</code> challenge to send to the client.
* It is <code>null</code> if the authentication has succeeded and there is
* no more challenge data to be sent to the client.
* @throws SaslException if an error occurred while processing the response
* or generating a challenge.
*/
byte[] evaluateResponse(byte[] response) throws SaslException;
/**
* Determines if the authentication exchange has completed. This method is
* typically called after each invocation of {@link #evaluateResponse(byte[])}
* to determine whether the authentication has completed successfully or
* should be continued.
*
* @return <code>true</code> if the authentication exchange has completed;
* <code>false</code> otherwise.
*/
boolean isComplete();
/**
* Reports the authorization ID in effect for the client of this session This
* method can only be called if {@link #isComplete()} returns <code>true</code>.
*
* @return the authorization ID of the client.
* @throws IllegalStateException if this authentication session has not
* completed.
*/
String getAuthorizationID();
/**
* <p>Unwraps a byte array received from the client. This method can be called
* only after the authentication exchange has completed (i.e., when
* {@link #isComplete()} returns <code>true</code>) and only if the
* authentication exchange has negotiated integrity and/or privacy as the
* quality of protection; otherwise, an {@link IllegalStateException} is
* thrown.</p>
*
* <p><code>incoming</code> is the contents of the SASL buffer as defined in
* RFC 2222 without the leading four octet field that represents the length.
* <code>offset</code> and <code>len</code> specify the portion of incoming
* to use.</p>
*
* @param incoming a non-null byte array containing the encoded bytes from
* the client.
* @param offset the starting position at <code>incoming</code> of the bytes
* to use.
* @param len the number of bytes from <code>incoming</code> to use.
* @return a non-null byte array containing the decoded bytes.
* @throws SaslException if <code>incoming</code> cannot be successfully
* unwrapped.
* @throws IllegalStateException if the authentication exchange has not
* completed, or if the negotiated quality of protection has neither
* integrity nor privacy.
*/
byte[] unwrap(byte[] incoming, int offset, int len) throws SaslException;
/**
* <p>Wraps a byte array to be sent to the client. This method can be called
* only after the authentication exchange has completed (i.e., when
* {@link #isComplete()} returns <code>true</code>) and only if the
* authentication exchange has negotiated integrity and/or privacy as the
* quality of protection; otherwise, an {@link IllegalStateException} is
* thrown.</p>
*
* <p>The result of this method will make up the contents of the SASL buffer
* as defined in RFC 2222 without the leading four octet field that
* represents the length. <code>offset</code> and <code>len</code> specify
* the portion of <code>outgoing</code> to use.
*
* @param outgoing a non-null byte array containing the bytes to encode.
* @param offset the starting position at <code>outgoing</code> of the bytes
* to use.
* @param len the number of bytes from <code>outgoing</code> to use.
* @return a non-null byte array containing the encoded bytes.
* @throws SaslException if <code>outgoing</code> cannot be successfully
* wrapped.
* @throws IllegalStateException if the authentication exchange has not
* completed, or if the negotiated quality of protection has neither
* integrity nor privacy.
*/
byte[] wrap(byte[] outgoing, int offset, int len) throws SaslException;
/**
* Retrieves the negotiated property. This method can be called only after
* the authentication exchange has completed (i.e., when
* {@link #isComplete()} returns <code>true</code>); otherwise, an
* {@link IllegalStateException} is thrown.
*
* @return the value of the negotiated property. If <code>null</code>, the
* property was not negotiated or is not applicable to this mechanism.
* @throws IllegalStateException if this authentication exchange has not
* completed.
*/
Object getNegotiatedProperty(String propName) throws SaslException;
/**
* Disposes of any system resources or security-sensitive information the
* <code>SaslServer</code> might be using. Invoking this method invalidates
* the <code>SaslServer</code> instance. This method is idempotent.
*
* @throws SaslException if a problem was encountered while disposing of the
* resources.
*/
void dispose() throws SaslException;
}