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
:
It can then proceed to use the client for authentication. For example, an LDAP library might use the client as follows:SaslClient sc = Sasl.createSaslClient(mechanisms, authorizationId, protocol, serverName, props, callbackHandler);
If the mechanism has an initial response, the library invokes// 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); } }
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.- Since:
- 1.5
- See Also:
-
Method Summary
Modifier and TypeMethodDescriptionvoid
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.Returns the IANA-registered mechanism name of this SASL client.getNegotiatedProperty
(String propName) Retrieves the negotiated property.boolean
Determines whether this mechanism has an optional initial response.boolean
Determines whether 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.
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Method Details
-
getMechanismName
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.
-
hasInitialResponse
boolean hasInitialResponse()Determines whether this mechanism has an optional initial response. If true, caller should callevaluateChallenge()
with an empty array to get the initial response.- Returns:
- true if this mechanism has an initial response.
-
evaluateChallenge
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 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.
- Throws:
SaslException
- If an error occurred while processing the challenge or generating a response.
-
isComplete
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.- Returns:
- true if the authentication exchange has completed; false otherwise.
-
unwrap
Unwraps a byte array received from the server. This method can be called only after the authentication exchange has completed (i.e., whenisComplete()
returns true) and only if the authentication exchange has negotiated integrity and/or privacy as the quality of protection; otherwise, anIllegalStateException
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
andlen
specify the portion ofincoming
to use.- Parameters:
incoming
- A non-null byte array containing the encoded bytes from the server.offset
- The starting position atincoming
of the bytes to use.len
- The number of bytes fromincoming
to use.- Returns:
- A non-null byte array containing the decoded bytes.
- Throws:
SaslException
- ifincoming
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
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()
returns true) and only if the authentication exchange has negotiated integrity and/or privacy as the quality of protection; otherwise, anIllegalStateException
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
andlen
specify the portion ofoutgoing
to use.- Parameters:
outgoing
- A non-null byte array containing the bytes to encode.offset
- The starting position atoutgoing
of the bytes to use.len
- The number of bytes fromoutgoing
to use.- Returns:
- A non-null byte array containing the encoded bytes.
- Throws:
SaslException
- ifoutgoing
cannot be successfully wrapped.IllegalStateException
- if the authentication exchange has not completed, or if the negotiated quality of protection has neither integrity nor privacy.
-
getNegotiatedProperty
Retrieves the negotiated property. This method can be called only after the authentication exchange has completed (i.e., whenisComplete()
returns true); otherwise, anIllegalStateException
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.- 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
-
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.- Throws:
SaslException
- If a problem was encountered while disposing the resources.
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