SSLEngine

See also:

• SSLContext
• SSLSocket
• SSLServerSocket
• SSLSession
• Socket

SSLEngine

protected SSLEngine ()

Constructor for an SSLEngine providing no hints for an internal session reuse strategy.

SSLEngine

protected SSLEngine (String peerHost, 
                int peerPort)

Constructor for an SSLEngine.

SSLEngine implementations may use the peerHost and peerPort parameters as hints for their internal session reuse strategy.

Some cipher suites (such as Kerberos) require remote hostname information. Implementations of this class should use this constructor to use Kerberos.

The parameters are not authenticated by the SSLEngine.

beginHandshake

public abstract void beginHandshake ()

Initiates handshaking (initial or renegotiation) on this SSLEngine.

This method is not needed for the initial handshake, as the wrap() and unwrap() methods will implicitly call this method if handshaking has not already begun.

Note that the peer may also request a session renegotiation with this SSLEngine by sending the appropriate session renegotiate handshake message.

Unlike the SSLSocket#startHandshake() method, this method does not block until handshaking is completed.

To force a complete SSL/TLS session renegotiation, the current session should be invalidated prior to calling this method.

Some protocols may not support multiple handshakes on an existing engine and may throw an SSLException.

closeInbound

public abstract void closeInbound ()

Signals that no more inbound network data will be sent to this SSLEngine.

If the application initiated the closing process by calling closeOutbound(), under some circumstances it is not required that the initiator wait for the peer's corresponding close message. (See section 7.2.1 of the TLS specification (RFC 2246) for more information on waiting for closure alerts.) In such cases, this method need not be called.

But if the application did not initiate the closure process, or if the circumstances above do not apply, this method should be called whenever the end of the SSL/TLS data stream is reached. This ensures closure of the inbound side, and checks that the peer followed the SSL/TLS close procedure properly, thus detecting possible truncation attacks.

This method is idempotent: if the inbound side has already been closed, this method does not do anything.

wrap() should be called to flush any remaining handshake data.

closeOutbound

public abstract void closeOutbound ()

Signals that no more outbound application data will be sent on this SSLEngine.

This method is idempotent: if the outbound side has already been closed, this method does not do anything.

wrap(java.nio.ByteBuffer, java.nio.ByteBuffer) should be called to flush any remaining handshake data.

getApplicationProtocol

public String getApplicationProtocol ()

Returns the most recent application protocol value negotiated for this connection.

If supported by the underlying SSL/TLS implementation, application name negotiation mechanisms such as RFC 7301 , the Application-Layer Protocol Negotiation (ALPN), can negotiate application-level values between peers.

getDelegatedTask

public abstract Runnable getDelegatedTask ()

Returns a delegated Runnable task for this SSLEngine.

SSLEngine operations may require the results of operations that block, or may take an extended period of time to complete. This method is used to obtain an outstanding Runnable operation (task). Each task must be assigned a thread (possibly the current) to perform the run operation. Once the run method returns, the Runnable object is no longer needed and may be discarded.

Delegated tasks run in the AccessControlContext in place when this object was created.

A call to this method will return each outstanding task exactly once.

Multiple delegated tasks can be run in parallel.

getEnableSessionCreation

public abstract boolean getEnableSessionCreation ()

Returns true if new SSL sessions may be established by this engine.

getEnabledCipherSuites

public abstract String[] getEnabledCipherSuites ()

Returns the names of the SSL cipher suites which are currently enabled for use on this engine. When an SSLEngine is first created, all enabled cipher suites support a minimum quality of service. Thus, in some environments this value might be empty.

Even if a suite has been enabled, it might never be used. (For example, the peer does not support it, the requisite certificates/private keys for the suite are not available, or an anonymous suite is enabled but authentication is required.)

getEnabledProtocols

public abstract String[] getEnabledProtocols ()

Returns the names of the protocol versions which are currently enabled for use with this SSLEngine.

getHandshakeApplicationProtocol

public String getHandshakeApplicationProtocol ()

Returns the application protocol value negotiated on a SSL/TLS handshake currently in progress.

Like getHandshakeSession(), a connection may be in the middle of a handshake. The application protocol may or may not yet be available.

getHandshakeApplicationProtocolSelector

public BiFunction<SSLEngine, List<String>, String> getHandshakeApplicationProtocolSelector ()

Retrieves the callback function that selects an application protocol value during a SSL/TLS handshake. See setHandshakeApplicationProtocolSelector for the function's type parameters.

getHandshakeSession

public SSLSession getHandshakeSession ()

Returns the SSLSession being constructed during a SSL/TLS handshake.

TLS protocols may negotiate parameters that are needed when using an instance of this class, but before the SSLSession has been completely initialized and made available via getSession. For example, the list of valid signature algorithms may restrict the type of certificates that can used during TrustManager decisions, or the maximum TLS fragment packet sizes can be resized to better support the network environment.

This method provides early access to the SSLSession being constructed. Depending on how far the handshake has progressed, some data may not yet be available for use. For example, if a remote server will be sending a Certificate chain, but that chain has yet not been processed, the getPeerCertificates method of SSLSession will throw a SSLPeerUnverifiedException. Once that chain has been processed, getPeerCertificates will return the proper value.

getHandshakeStatus

public abstract SSLEngineResult.HandshakeStatus getHandshakeStatus ()

Returns the current handshake status for this SSLEngine.

getNeedClientAuth

public abstract boolean getNeedClientAuth ()

Returns true if the engine will require client authentication. This option is only useful to engines in the server mode.

getPeerHost

public String getPeerHost ()

Returns the host name of the peer.

Note that the value is not authenticated, and should not be relied upon.

getPeerPort

public int getPeerPort ()

Returns the port number of the peer.

Note that the value is not authenticated, and should not be relied upon.

getSSLParameters

public SSLParameters getSSLParameters ()

Returns the SSLParameters in effect for this SSLEngine. The ciphersuites and protocols of the returned SSLParameters are always non-null.

getSession

public abstract SSLSession getSession ()

Returns the SSLSession in use in this SSLEngine.

These can be long lived, and frequently correspond to an entire login session for some user. The session specifies a particular cipher suite which is being actively used by all connections in that session, as well as the identities of the session's client and server.

Unlike SSLSocket#getSession() this method does not block until handshaking is complete.

Until the initial handshake has completed, this method returns a session object which reports an invalid cipher suite of "SSL_NULL_WITH_NULL_NULL".

getSupportedCipherSuites

public abstract String[] getSupportedCipherSuites ()

Returns the names of the cipher suites which could be enabled for use on this engine. Normally, only a subset of these will actually be enabled by default, since this list may include cipher suites which do not meet quality of service requirements for those defaults. Such cipher suites might be useful in specialized applications.

Applications should not blindly enable all supported cipher suites. The supported cipher suites can include signaling cipher suite values that can cause connection problems if enabled inappropriately.

The proper way to use this method is to either check if a specific cipher suite is supported via Arrays.asList(getSupportedCipherSuites()).contains(...) or to filter a desired list of cipher suites to only the supported ones via desiredSuiteSet.retainAll(Arrays.asList(getSupportedCipherSuites())).

getSupportedProtocols

public abstract String[] getSupportedProtocols ()

Returns the names of the protocols which could be enabled for use with this SSLEngine.

getUseClientMode

public abstract boolean getUseClientMode ()

Returns true if the engine is set to use client mode when handshaking.

getWantClientAuth

public abstract boolean getWantClientAuth ()

Returns true if the engine will request client authentication. This option is only useful for engines in the server mode.

isInboundDone

public abstract boolean isInboundDone ()

Returns whether unwrap(java.nio.ByteBuffer, java.nio.ByteBuffer) will accept any more inbound data messages.

isOutboundDone

public abstract boolean isOutboundDone ()

Returns whether wrap(java.nio.ByteBuffer, java.nio.ByteBuffer) will produce any more outbound data messages.

Note that during the closure phase, a SSLEngine may generate handshake closure data that must be sent to the peer. wrap() must be called to generate this data. When this method returns true, no more outbound data will be created.

setEnableSessionCreation

public abstract void setEnableSessionCreation (boolean flag)

Controls whether new SSL sessions may be established by this engine. If session creations are not allowed, and there are no existing sessions to resume, there will be no successful handshaking.

setEnabledCipherSuites

public abstract void setEnabledCipherSuites (String[] suites)

Sets the cipher suites enabled for use on this engine.

Each cipher suite in the suites parameter must have been listed by getSupportedCipherSuites(), or the method will fail. Following a successful call to this method, only suites listed in the suites parameter are enabled for use.

See getEnabledCipherSuites() for more information on why a specific cipher suite may never be used on a engine.

setEnabledProtocols

public abstract void setEnabledProtocols (String[] protocols)

Set the protocol versions enabled for use on this engine.

The protocols must have been listed by getSupportedProtocols() as being supported. Following a successful call to this method, only protocols listed in the protocols parameter are enabled for use.

Because of the way the protocol version is negotiated, connections will only be able to use a member of the lowest set of contiguous enabled protocol versions. For example, enabling TLSv1.2 and TLSv1 will result in connections only being able to use TLSv1.

setHandshakeApplicationProtocolSelector

public void setHandshakeApplicationProtocolSelector (BiFunction<SSLEngine, List<String>, String> selector)

Registers a callback function that selects an application protocol value for a SSL/TLS handshake. The function overrides any values supplied using SSLParameters.setApplicationProtocols and it supports the following type parameters:

SSLEngine

The function's first argument allows the current SSLEngine to be inspected, including the handshake session and configuration settings.

List<String>

The function's second argument lists the application protocol names advertised by the TLS peer.

String

The function's result is an application protocol name, or null to indicate that none of the advertised names are acceptable. If the return value is an empty String then application protocol indications will not be used. If the return value is null (no value chosen) or is a value that was not advertised by the peer, the underlying protocol will determine what action to take. (For example, ALPN will send a "no_application_protocol" alert and terminate the connection.)

serverEngine.setHandshakeApplicationProtocolSelector(
         (serverEngine, clientProtocols) -> {
             SSLSession session = serverEngine.getHandshakeSession();
             return chooseApplicationProtocol(
                 serverEngine,
                 clientProtocols,
                 session.getProtocol(),
                 session.getCipherSuite());
         });
 

setNeedClientAuth

public abstract void setNeedClientAuth (boolean need)

Configures the engine to require client authentication. This option is only useful for engines in the server mode.

An engine's client authentication setting is one of the following:

• client authentication required
• client authentication requested
• no client authentication desired

Unlike setWantClientAuth(boolean), if this option is set and the client chooses not to provide authentication information about itself, the negotiations will stop and the engine will begin its closure procedure.

Calling this method overrides any previous setting made by this method or setWantClientAuth(boolean).

setSSLParameters

public void setSSLParameters (SSLParameters params)

Applies SSLParameters to this engine.

This means:

• If params.getCipherSuites() is non-null, setEnabledCipherSuites() is called with that value.
• If params.getProtocols() is non-null, setEnabledProtocols() is called with that value.
• If params.getNeedClientAuth() or params.getWantClientAuth() return true, setNeedClientAuth(true) and setWantClientAuth(true) are called, respectively; otherwise setWantClientAuth(false) is called.
• If params.getServerNames() is non-null, the engine will configure its server names with that value.
• If params.getSNIMatchers() is non-null, the engine will configure its SNI matchers with that value.

setUseClientMode

public abstract void setUseClientMode (boolean mode)

Configures the engine to use client (or server) mode when handshaking.

This method must be called before any handshaking occurs. Once handshaking has begun, the mode can not be reset for the life of this engine.

Servers normally authenticate themselves, and clients are not required to do so.

setWantClientAuth

public abstract void setWantClientAuth (boolean want)

Configures the engine to request client authentication. This option is only useful for engines in the server mode.

An engine's client authentication setting is one of the following:

• client authentication required
• client authentication requested
• no client authentication desired

Unlike setNeedClientAuth(boolean), if this option is set and the client chooses not to provide authentication information about itself, the negotiations will continue.

Calling this method overrides any previous setting made by this method or setNeedClientAuth(boolean).

unwrap

public SSLEngineResult unwrap (ByteBuffer src, 
                ByteBuffer[] dsts)

Attempts to decode SSL/TLS network data into a sequence of plaintext application data buffers.

An invocation of this method behaves in exactly the same manner as the invocation:

 engine.unwrap(src, dsts, 0, dsts.length);
 

unwrap

public SSLEngineResult unwrap (ByteBuffer src, 
                ByteBuffer dst)

Attempts to decode SSL/TLS network data into a plaintext application data buffer.

An invocation of this method behaves in exactly the same manner as the invocation:

 engine.unwrap(src, new ByteBuffer [] { dst }, 0, 1);
 

unwrap

public abstract SSLEngineResult unwrap (ByteBuffer src, 
                ByteBuffer[] dsts, 
                int offset, 
                int length)

Attempts to decode SSL/TLS network data into a subsequence of plaintext application data buffers. This "scattering" operation decodes, in a single invocation, a sequence of bytes into one or more of a given sequence of buffers. Scattering unwraps are often useful when implementing network protocols or file formats that, for example, group data into segments consisting of one or more fixed-length headers followed by a variable-length body. See ScatteringByteChannel for more information on scattering, and ScatteringByteChannel.read(ByteBuffer[], int, int) for more information on the subsequence behavior.

Depending on the state of the SSLEngine, this method may consume network data without producing any application data (for example, it may consume handshake data.)

The application is responsible for reliably obtaining the network data from the peer, and for invoking unwrap() on the data in the order it was received. The application must properly synchronize multiple calls to this method.

If this SSLEngine has not yet started its initial handshake, this method will automatically start the handshake.

This method will attempt to consume one complete SSL/TLS network packet, but will never consume more than the sum of the bytes remaining in the buffers. Each ByteBuffer's position is updated to reflect the amount of data consumed or produced. The limits remain the same.

The underlying memory used by the src and dsts ByteBuffers must not be the same.

The inbound network buffer may be modified as a result of this call: therefore if the network data packet is required for some secondary purpose, the data should be duplicated before calling this method. Note: the network data will not be useful to a second SSLEngine, as each SSLEngine contains unique random state which influences the SSL/TLS messages.

See the class description for more information on engine closure.

wrap

public SSLEngineResult wrap (ByteBuffer[] srcs, 
                ByteBuffer dst)

Attempts to encode plaintext bytes from a sequence of data buffers into SSL/TLS network data.

An invocation of this method behaves in exactly the same manner as the invocation:

 engine.wrap(srcs, 0, srcs.length, dst);
 

wrap

public SSLEngineResult wrap (ByteBuffer src, 
                ByteBuffer dst)

Attempts to encode a buffer of plaintext application data into SSL/TLS network data.

An invocation of this method behaves in exactly the same manner as the invocation:

 engine.wrap(new ByteBuffer [] { src }, 0, 1, dst);
 

wrap

public abstract SSLEngineResult wrap (ByteBuffer[] srcs, 
                int offset, 
                int length, 
                ByteBuffer dst)

Attempts to encode plaintext bytes from a subsequence of data buffers into SSL/TLS network data. This "gathering" operation encodes, in a single invocation, a sequence of bytes from one or more of a given sequence of buffers. Gathering wraps are often useful when implementing network protocols or file formats that, for example, group data into segments consisting of one or more fixed-length headers followed by a variable-length body. See GatheringByteChannel for more information on gathering, and GatheringByteChannel.write(ByteBuffer[], int, int) for more information on the subsequence behavior.

Depending on the state of the SSLEngine, this method may produce network data without consuming any application data (for example, it may generate handshake data.)

The application is responsible for reliably transporting the network data to the peer, and for ensuring that data created by multiple calls to wrap() is transported in the same order in which it was generated. The application must properly synchronize multiple calls to this method.

If this SSLEngine has not yet started its initial handshake, this method will automatically start the handshake.

This method will attempt to produce SSL/TLS records, and will consume as much source data as possible, but will never consume more than the sum of the bytes remaining in each buffer. Each ByteBuffer's position is updated to reflect the amount of data consumed or produced. The limits remain the same.

The underlying memory used by the srcs and dst ByteBuffers must not be the same.

See the class description for more information on engine closure.