SaslClientpublic abstract interface SaslClient | 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. |
| Methods Summary |
|---|
| public abstract void | dispose()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.
| | public abstract byte[] | evaluateChallenge(byte[] challenge)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.
| | public abstract java.lang.String | getMechanismName()Returns the IANA-registered mechanism name of this SASL client.
(e.g. "CRAM-MD5", "GSSAPI").
| | public abstract java.lang.Object | getNegotiatedProperty(java.lang.String propName)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.
| | public abstract boolean | hasInitialResponse()Determines whether this mechanism has an optional initial response.
If true, caller should call evaluateChallenge() with an
empty array to get the initial response.
| | public abstract boolean | isComplete()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.
| | public abstract byte[] | unwrap(byte[] incoming, int offset, int len)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.
| | public abstract byte[] | wrap(byte[] outgoing, int offset, int len)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.
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