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public interface SaslClientA 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(byte[]) with an empty challenge to get the initial
response. Protocols such as IMAP4, which do not include an initial response
with their first authentication command to the server, initiate the
authentication without first calling hasInitialResponse() or
evaluateChallenge(byte[]). 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(byte[])
with an empty challenge.
Sasl, SaslClientFactoryMethod Summary | |
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public void dispose() throws SaslException
Disposes of any system resources or security-sensitive information theSaslClientmight be using. Invoking this method invalidates theSaslClientinstance. This method is idempotent.
- Throws:
SaslException- if a problem was encountered while disposing of the resources.
public byte[] evaluateChallenge(byte[] challenge) throws SaslException
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.
- Parameters:
challenge- the non-null challenge sent from the server. The challenge array may have zero length.
- Returns:
- the possibly
nullreponse to send to the server. It isnullif 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.
- Throws:
SaslException- if an error occurred while processing the challenge or generating a response.
public String getMechanismName()
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.
public Object getNegotiatedProperty(String propName)
Retrieves the negotiated property. This method can be called only after the authentication exchange has completed (i.e., whenisComplete()returnstrue); otherwise, anIllegalStateExceptionis thrown.
- Parameters:
propName- the non-null property name.
- Returns:
- the value of the negotiated property. If
null, the property was not negotiated or is not applicable to this mechanism.
- Throws:
IllegalStateException- if this authentication exchange has not completed.
public boolean hasInitialResponse()
Determines if this mechanism has an optional initial response. Iftrue, caller should callevaluateChallenge(byte[])with an empty array to get the initial response.
- Returns:
trueif this mechanism has an initial response.
public boolean isComplete()
Determines if 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:
trueif the authentication exchange has completed;falseotherwise.
public byte[] unwrap(byte[] incoming, int offset, int len) throws SaslException
Unwraps a byte array received from the server. This method can be called only after the authentication exchange has completed (i.e., whenisComplete()returnstrue) and only if the authentication exchange has negotiated integrity and/or privacy as the quality of protection; otherwise, anIllegalStateExceptionis thrown.
incomingis the contents of the SASL buffer as defined in RFC 2222 without the leading four octet field that represents the length.offsetandlenspecify the portion of incoming to use.
- Parameters:
incoming- a non-null byte array containing the encoded bytes from the server.offset- the starting position atincomingof the bytes to use.len- the number of bytes fromincomingto use.
- Returns:
- a non-null byte array containing the decoded bytes.
- Throws:
SaslException- ifincomingcannot be successfully unwrapped.IllegalStateException- if the authentication exchange has not completed, or if the negotiated quality of protection has neither integrity nor privacy.
public byte[] wrap(byte[] outgoing, 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., whenisComplete()returnstrue) and only if the authentication exchange has negotiated integrity and/or privacy as the quality of protection; otherwise, anIllegalStateExceptionis 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.
offsetandlenspecify the portion ofoutgoingto use.
- Parameters:
outgoing- a non-null byte array containing the bytes to encode.offset- the starting position atoutgoingof the bytes to use.len- the number of bytes fromoutgoingto use.
- Returns:
- a non-null byte array containing the encoded bytes.
- Throws:
SaslException- ifoutgoingcannot be successfully wrapped.IllegalStateException- if the authentication exchange has not completed, or if the negotiated quality of protection has neither integrity nor privacy.