javax.security.sasl
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(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.
void | dispose()- Disposes of any system resources or security-sensitive information the
SaslClient might be using.
|
byte[] | evaluateChallenge(byte[] challenge)- Evaluates the challenge data and generates a response.
|
String | getMechanismName()- Returns the IANA-registered mechanism name of this SASL client. (e.g.
|
Object | getNegotiatedProperty(String propName)- Retrieves the negotiated property.
|
boolean | hasInitialResponse()- Determines if this mechanism has an optional initial response.
|
boolean | isComplete()- Determines if the authentication exchange has completed.
|
byte[] | unwrap(byte[] incoming, int offset, int len)- Unwraps a byte array received from the server.
|
byte[] | wrap(byte[] outgoing, int offset, int len)- Wraps a byte array to be sent to the server.
|
dispose
public void dispose()
throws SaslException 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.
SaslException - if a problem was encountered while disposing of the
resources.
evaluateChallenge
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.
challenge - the non-null challenge sent from the server. The
challenge array may have zero length.
- the possibly
null reponse 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.
SaslException - if an error occurred while processing the challenge
or generating a response.
getMechanismName
public String getMechanismName()
Returns the IANA-registered mechanism name of this SASL client. (e.g.
"CRAM-MD5", "GSSAPI").
- a non-null string representing the IANA-registered mechanism name.
getNegotiatedProperty
public Object getNegotiatedProperty(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.
propName - the non-null property name.
- the value of the negotiated property. If
null, the
property was not negotiated or is not applicable to this mechanism.
hasInitialResponse
public boolean hasInitialResponse()
Determines if this mechanism has an optional initial response. If
true, caller should call
evaluateChallenge(byte[])
with an empty array to get the initial response.
true if this mechanism has an initial response.
isComplete
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.
true if the authentication exchange has completed;
false otherwise.
unwrap
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., 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.
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.
- a non-null byte array containing the decoded bytes.
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.
wrap
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., 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.
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.
- a non-null byte array containing the encoded bytes.
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.
SaslClient.java --
Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.
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