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package javax.security.sasl;
Performs SASL authentication as a client.
A protocol library such as one for LDAP gets an instance of this class in order to perform authentication defined by a specific SASL mechanism. Invoking methods on the SaslClient instance process challenges and create responses according to the SASL mechanism implemented by the SaslClient. As the authentication proceeds, the instance encapsulates the state of a SASL client's authentication exchange.
Here's an example of how an LDAP library might use a SaslClient. It first gets an instance of a SaslClient:
SaslClient sc = Sasl.createSaslClient(mechanisms,
authorizationId, protocol, serverName, props, callbackHandler);
It can then proceed to use the client for authentication.
For example, an LDAP library might use the client as follows:
// Get initial response and send to server
byte[] response = (sc.hasInitialResponse() ? sc.evaluateChallenge(new byte[0]) :
null);
LdapResult res = ldap.sendBindRequest(dn, sc.getName(), response);
while (!sc.isComplete() &&
(res.status == SASL_BIND_IN_PROGRESS || res.status == SUCCESS)) {
response = sc.evaluateChallenge(res.getBytes());
if (res.status == SUCCESS) {
// we're done; don't expect to send another BIND
if (response != null) {
throw new SaslException(
"Protocol error: attempting to send response after completion");
}
break;
}
res = ldap.sendBindRequest(dn, sc.getName(), response);
}
if (sc.isComplete() && res.status == SUCCESS) {
String qop = (String) sc.getNegotiatedProperty(Sasl.QOP);
if (qop != null
&& (qop.equalsIgnoreCase("auth-int")
|| qop.equalsIgnoreCase("auth-conf"))) {
// Use SaslClient.wrap() and SaslClient.unwrap() for future
// communication with server
ldap.in = new SecureInputStream(sc, ldap.in);
ldap.out = new SecureOutputStream(sc, ldap.out);
}
}
If the mechanism has an initial response, the library invokes evaluateChallenge() with an empty challenge and to get initial response. Protocols such as IMAP4, which do not include an initial response with their first authentication command to the server, initiates the authentication without first calling hasInitialResponse() or evaluateChallenge(). When the server responds to the command, it sends an initial challenge. For a SASL mechanism in which the client sends data first, the server should have issued a challenge with no data. This will then result in a call (on the client) to evaluateChallenge() with an empty challenge. Author: Rosanna Lee, Rob Weltman See Also: Since: 1.5
/**
* Performs SASL authentication as a client.
* <p>
* A protocol library such as one for LDAP gets an instance of this
* class in order to perform authentication defined by a specific SASL
* mechanism. Invoking methods on the {@code SaslClient} instance
* process challenges and create responses according to the SASL
* mechanism implemented by the {@code SaslClient}.
* As the authentication proceeds, the instance
* encapsulates the state of a SASL client's authentication exchange.
* <p>
* Here's an example of how an LDAP library might use a {@code SaslClient}.
* It first gets an instance of a {@code SaslClient}:
* <blockquote><pre>{@code
* SaslClient sc = Sasl.createSaslClient(mechanisms,
* authorizationId, protocol, serverName, props, callbackHandler);
* }</pre></blockquote>
* It can then proceed to use the client for authentication.
* For example, an LDAP library might use the client as follows:
* <blockquote><pre>{@code
* // Get initial response and send to server
* byte[] response = (sc.hasInitialResponse() ? sc.evaluateChallenge(new byte[0]) :
* null);
* LdapResult res = ldap.sendBindRequest(dn, sc.getName(), response);
* while (!sc.isComplete() &&
* (res.status == SASL_BIND_IN_PROGRESS || res.status == SUCCESS)) {
* response = sc.evaluateChallenge(res.getBytes());
* if (res.status == SUCCESS) {
* // we're done; don't expect to send another BIND
* if (response != null) {
* throw new SaslException(
* "Protocol error: attempting to send response after completion");
* }
* break;
* }
* res = ldap.sendBindRequest(dn, sc.getName(), response);
* }
* if (sc.isComplete() && res.status == SUCCESS) {
* String qop = (String) sc.getNegotiatedProperty(Sasl.QOP);
* if (qop != null
* && (qop.equalsIgnoreCase("auth-int")
* || qop.equalsIgnoreCase("auth-conf"))) {
*
* // Use SaslClient.wrap() and SaslClient.unwrap() for future
* // communication with server
* ldap.in = new SecureInputStream(sc, ldap.in);
* ldap.out = new SecureOutputStream(sc, ldap.out);
* }
* }
* }</pre></blockquote>
*
* If the mechanism has an initial response, the library invokes
* {@code evaluateChallenge()} with an empty
* challenge and to get initial response.
* Protocols such as IMAP4, which do not include an initial response with
* their first authentication command to the server, initiates the
* authentication without first calling {@code hasInitialResponse()}
* or {@code evaluateChallenge()}.
* When the server responds to the command, it sends an initial challenge.
* For a SASL mechanism in which the client sends data first, the server should
* have issued a challenge with no data. This will then result in a call
* (on the client) to {@code evaluateChallenge()} with an empty challenge.
*
* @since 1.5
*
* @see Sasl
* @see SaslClientFactory
*
* @author Rosanna Lee
* @author Rob Weltman
*/
public abstract interface SaslClient {
Returns the IANA-registered mechanism name of this SASL client.
(e.g. "CRAM-MD5", "GSSAPI").
Returns: A non-null string representing the IANA-registered mechanism name.
/**
* Returns the IANA-registered mechanism name of this SASL client.
* (e.g. "CRAM-MD5", "GSSAPI").
* @return A non-null string representing the IANA-registered mechanism name.
*/
public abstract String getMechanismName();
Determines whether this mechanism has an optional initial response. If true, caller should call evaluateChallenge() with an empty array to get the initial response. Returns: true if this mechanism has an initial response.
/**
* Determines whether this mechanism has an optional initial response.
* If true, caller should call {@code evaluateChallenge()} with an
* empty array to get the initial response.
*
* @return true if this mechanism has an initial response.
*/
public abstract boolean hasInitialResponse();
Evaluates the challenge data and generates a response.
If a challenge is received from the server during the authentication
process, this method is called to prepare an appropriate next
response to submit to the server.
Params: - challenge – The non-null challenge sent from the server.
The challenge array may have zero length.
Throws: - SaslException – If an error occurred while processing
the challenge or generating a response.
Returns: The possibly null response to send to the server.
It is null if the challenge accompanied a "SUCCESS" status and the challenge
only contains data for the client to update its state and no response
needs to be sent to the server. The response is a zero-length byte
array if the client is to send a response with no data.
/**
* Evaluates the challenge data and generates a response.
* If a challenge is received from the server during the authentication
* process, this method is called to prepare an appropriate next
* response to submit to the server.
*
* @param challenge The non-null challenge sent from the server.
* The challenge array may have zero length.
*
* @return The possibly null response to send to the server.
* It is null if the challenge accompanied a "SUCCESS" status and the challenge
* only contains data for the client to update its state and no response
* needs to be sent to the server. The response is a zero-length byte
* array if the client is to send a response with no data.
* @exception SaslException If an error occurred while processing
* the challenge or generating a response.
*/
public abstract byte[] evaluateChallenge(byte[] challenge)
throws SaslException;
Determines whether the authentication exchange has completed.
This method may be called at any time, but typically, it
will not be called until the caller has received indication
from the server
(in a protocol-specific manner) that the exchange has completed.
Returns: true if the authentication exchange has completed; false otherwise.
/**
* Determines whether the authentication exchange has completed.
* This method may be called at any time, but typically, it
* will not be called until the caller has received indication
* from the server
* (in a protocol-specific manner) that the exchange has completed.
*
* @return true if the authentication exchange has completed; false otherwise.
*/
public abstract boolean isComplete();
Unwraps a byte array received from the server. This method can be called only after the authentication exchange has completed (i.e., when isComplete() returns true) and only if the authentication exchange has negotiated integrity and/or privacy as the quality of protection; otherwise, an IllegalStateException is thrown. incoming is the contents of the SASL buffer as defined in RFC 2222 without the leading four octet field that represents the length. offset and len specify the portion of incoming to use.
Params: - incoming – A non-null byte array containing the encoded bytes
from the server.
- offset – The starting position at
incoming of the bytes to use. - len – The number of bytes from
incoming to use.
Throws: - SaslException – if
incoming cannot be successfully unwrapped. - IllegalStateException – if the authentication exchange has
not completed, or if the negotiated quality of protection
has neither integrity nor privacy.
Returns: A non-null byte array containing the decoded bytes.
/**
* Unwraps a byte array received from the server.
* This method can be called only after the authentication exchange has
* completed (i.e., when {@code isComplete()} returns true) and only if
* the authentication exchange has negotiated integrity and/or privacy
* as the quality of protection; otherwise, an
* {@code IllegalStateException} is thrown.
* <p>
* {@code incoming} is the contents of the SASL buffer as defined in RFC 2222
* without the leading four octet field that represents the length.
* {@code offset} and {@code len} specify the portion of {@code incoming}
* to use.
*
* @param incoming A non-null byte array containing the encoded bytes
* from the server.
* @param offset The starting position at {@code incoming} of the bytes to use.
* @param len The number of bytes from {@code incoming} to use.
* @return A non-null byte array containing the decoded bytes.
* @exception SaslException if {@code incoming} cannot be successfully
* unwrapped.
* @exception IllegalStateException if the authentication exchange has
* not completed, or if the negotiated quality of protection
* has neither integrity nor privacy.
*/
public abstract byte[] unwrap(byte[] incoming, int offset, int len)
throws SaslException;
Wraps a byte array to be sent to the server. This method can be called only after the authentication exchange has completed (i.e., when isComplete() returns true) and only if the authentication exchange has negotiated integrity and/or privacy as the quality of protection; otherwise, an IllegalStateException is thrown. 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. offset and len specify the portion of outgoing to use.
Params: - outgoing – A non-null byte array containing the bytes to encode.
- offset – The starting position at
outgoing of the bytes to use. - len – The number of bytes from
outgoing to use.
Throws: - SaslException – if
outgoing cannot be successfully wrapped. - IllegalStateException – if the authentication exchange has
not completed, or if the negotiated quality of protection
has neither integrity nor privacy.
Returns: A non-null byte array containing the encoded bytes.
/**
* Wraps a byte array to be sent to the server.
* This method can be called only after the authentication exchange has
* completed (i.e., when {@code isComplete()} returns true) and only if
* the authentication exchange has negotiated integrity and/or privacy
* as the quality of protection; otherwise, an
* {@code IllegalStateException} is thrown.
* <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} and {@code len} specify the portion of {@code outgoing}
* to use.
*
* @param outgoing A non-null byte array containing the bytes to encode.
* @param offset The starting position at {@code outgoing} of the bytes to use.
* @param len The number of bytes from {@code outgoing} to use.
* @return A non-null byte array containing the encoded bytes.
* @exception SaslException if {@code outgoing} cannot be successfully
* wrapped.
* @exception IllegalStateException if the authentication exchange has
* not completed, or if the negotiated quality of protection
* has neither integrity nor privacy.
*/
public abstract 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 isComplete() returns true); otherwise, an IllegalStateException is thrown. The Sasl class includes several well-known property names (For example, Sasl.QOP). A SASL provider can support other properties which are specific to the vendor and/or a mechanism.
Params: - propName – The non-null property name.
Throws: - IllegalStateException – if this authentication exchange
has not completed
Returns: The value of the negotiated property. If null, the property was
not negotiated or is not applicable to this mechanism.
/**
* Retrieves the negotiated property.
* This method can be called only after the authentication exchange has
* completed (i.e., when {@code isComplete()} returns true); otherwise, an
* {@code IllegalStateException} is thrown.
* <p>
* The {@link Sasl} class includes several well-known property names
* (For example, {@link Sasl#QOP}). A SASL provider can support other
* properties which are specific to the vendor and/or a mechanism.
*
* @param propName The non-null property name.
* @return The value of the negotiated property. If null, the property was
* not negotiated or is not applicable to this mechanism.
* @exception IllegalStateException if this authentication exchange
* has not completed
*/
public abstract Object getNegotiatedProperty(String propName);
Disposes of any system resources or security-sensitive information
the SaslClient might be using. Invoking this method invalidates
the SaslClient instance. This method is idempotent.
Throws: - SaslException – If a problem was encountered while disposing
the resources.
/**
* Disposes of any system resources or security-sensitive information
* the SaslClient might be using. Invoking this method invalidates
* the SaslClient instance. This method is idempotent.
* @throws SaslException If a problem was encountered while disposing
* the resources.
*/
public abstract void dispose() throws SaslException;
}