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.
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Performs SASL authentication as a client.
