public abstract class SSLEngine extends Object
The secure communications modes include:
The cipher suite used is established by a negotiation process called "handshaking". The goal of this process is to create or rejoin a "session", which may protect many connections over time. After handshaking has completed, you can access session attributes by using the getSession()
method.
The SSLSocket
class provides much of the same security functionality, but all the inbound and outbound data is automatically transported using the underlying Socket
, which by design uses a blocking model. While this is appropriate for many applications, this model does not provide the scalability required by large servers.
The primary distinction of an SSLEngine
is that it operates on inbound and outbound byte streams, independent of the transport mechanism. It is the responsibility of the SSLEngine
user to arrange for reliable I/O transport to the peer. By separating the SSL/TLS/DTLS abstraction from the I/O transport mechanism, the SSLEngine
can be used for a wide variety of I/O types, such as non-blocking I/O (polling)
, selectable non-blocking I/O
, Socket
and the traditional Input/OutputStreams, local ByteBuffers
or byte arrays, future asynchronous I/O models , and so on.
At a high level, the SSLEngine
appears thus:
app data | ^ | | | v | | +----+-----|-----+----+ | | | | SSL|Engine | wrap() | | | unwrap() | OUTBOUND | INBOUND | | | | +----+-----|-----+----+ | | ^ | | | v | net dataApplication data (also known as plaintext or cleartext) is data which is produced or consumed by an application. Its counterpart is network data, which consists of either handshaking and/or ciphertext (encrypted) data, and destined to be transported via an I/O mechanism. Inbound data is data which has been received from the peer, and outbound data is destined for the peer.
(In the context of an SSLEngine
, the term "handshake data" is taken to mean any data exchanged to establish and control a secure connection. Handshake data includes the SSL/TLS/DTLS messages "alert", "change_cipher_spec," and "handshake.")
There are five distinct phases to an SSLEngine
.
SSLEngine
has been created and initialized, but has not yet been used. During this phase, an application may set any SSLEngine
-specific settings (enabled cipher suites, whether the SSLEngine
should handshake in client or server mode, and so on). Once handshaking has begun, though, any new settings (except client/server mode, see below) will be used for the next handshake. SSLEngine
. Outbound application messages are encrypted and integrity protected, and inbound messages reverse the process. SSLEngine
configuration settings will not be used until the next handshake. SSLEngine
objects, an application should call closeOutbound()
and send any remaining messages to the peer. Likewise, an application should receive any remaining messages from the peer before calling closeInbound()
. The underlying transport mechanism can then be closed after both sides of the SSLEngine
have been closed. If the connection is not closed in an orderly manner (for example closeInbound()
is called before the peer's write closure notification has been received), exceptions will be raised to indicate that an error has occurred. Once an engine is closed, it is not reusable: a new SSLEngine
must be created. SSLEngine
is created by calling SSLContext.createSSLEngine()
from an initialized SSLContext
. Any configuration parameters should be set before making the first call to wrap()
, unwrap()
, or beginHandshake()
. These methods all trigger the initial handshake. Data moves through the engine by calling wrap()
or unwrap()
on outbound or inbound data, respectively. Depending on the state of the SSLEngine
, a wrap()
call may consume application data from the source buffer and may produce network data in the destination buffer. The outbound data may contain application and/or handshake data. A call to unwrap()
will examine the source buffer and may advance the handshake if the data is handshaking information, or may place application data in the destination buffer if the data is application. The state of the underlying SSL/TLS/DTLS algorithm will determine when data is consumed and produced.
Calls to wrap()
and unwrap()
return an SSLEngineResult
which indicates the status of the operation, and (optionally) how to interact with the engine to make progress.
The SSLEngine
produces/consumes complete SSL/TLS/DTLS packets only, and does not store application data internally between calls to wrap()/unwrap()
. Thus input and output ByteBuffer
s must be sized appropriately to hold the maximum record that can be produced. Calls to SSLSession.getPacketBufferSize()
and SSLSession.getApplicationBufferSize()
should be used to determine the appropriate buffer sizes. The size of the outbound application data buffer generally does not matter. If buffer conditions do not allow for the proper consumption/production of data, the application must determine (via SSLEngineResult
) and correct the problem, and then try the call again.
For example, unwrap()
will return a SSLEngineResult.Status.BUFFER_OVERFLOW
result if the engine determines that there is not enough destination buffer space available. Applications should call SSLSession.getApplicationBufferSize()
and compare that value with the space available in the destination buffer, enlarging the buffer if necessary. Similarly, if unwrap()
were to return a SSLEngineResult.Status.BUFFER_UNDERFLOW
, the application should call SSLSession.getPacketBufferSize()
to ensure that the source buffer has enough room to hold a record (enlarging if necessary), and then obtain more inbound data.
SSLEngineResult r = engine.unwrap(src, dst);
switch (r.getStatus()) {
case BUFFER_OVERFLOW:
// Could attempt to drain the dst buffer of any already obtained
// data, but we'll just increase it to the size needed.
int appSize = engine.getSession().getApplicationBufferSize();
ByteBuffer b = ByteBuffer.allocate(appSize + dst.position());
dst.flip();
b.put(dst);
dst = b;
// retry the operation.
break;
case BUFFER_UNDERFLOW:
int netSize = engine.getSession().getPacketBufferSize();
// Resize buffer if needed.
if (netSize > src.capacity()) {
ByteBuffer b = ByteBuffer.allocate(netSize);
src.flip();
b.put(src);
src = b;
}
// Obtain more inbound network data for src,
// then retry the operation.
break;
// other cases: CLOSED, OK.
}
Unlike SSLSocket
, all methods of SSLEngine are non-blocking. SSLEngine
implementations may require the results of tasks that may take an extended period of time to complete, or may even block. For example, a TrustManager may need to connect to a remote certificate validation service, or a KeyManager might need to prompt a user to determine which certificate to use as part of client authentication. Additionally, creating cryptographic signatures and verifying them can be slow, seemingly blocking.
For any operation which may potentially block, the SSLEngine
will create a Runnable
delegated task. When SSLEngineResult
indicates that a delegated task result is needed, the application must call getDelegatedTask()
to obtain an outstanding delegated task and call its run()
method (possibly using a different thread depending on the compute strategy). The application should continue obtaining delegated tasks until no more exist, and try the original operation again.
At the end of a communication session, applications should properly close the SSL/TLS/DTLS link. The SSL/TLS/DTLS protocols have closure handshake messages, and these messages should be communicated to the peer before releasing the SSLEngine
and closing the underlying transport mechanism. A close can be initiated by one of: an SSLException, an inbound closure handshake message, or one of the close methods. In all cases, closure handshake messages are generated by the engine, and wrap()
should be repeatedly called until the resulting SSLEngineResult
's status returns "CLOSED", or isOutboundDone()
returns true. All data obtained from the wrap()
method should be sent to the peer.
closeOutbound()
is used to signal the engine that the application will not be sending any more data.
A peer will signal its intent to close by sending its own closure handshake message. After this message has been received and processed by the local SSLEngine
's unwrap()
call, the application can detect the close by calling unwrap()
and looking for a SSLEngineResult
with status "CLOSED", or if isInboundDone()
returns true. If for some reason the peer closes the communication link without sending the proper SSL/TLS/DTLS closure message, the application can detect the end-of-stream and can signal the engine via closeInbound()
that there will no more inbound messages to process. Some applications might choose to require orderly shutdown messages from a peer, in which case they can check that the closure was generated by a handshake message and not by an end-of-stream condition.
There are two groups of cipher suites which you will need to know about when managing cipher suites:
getSupportedCipherSuites()
. setEnabledCipherSuites(String[])
method, and queried using the getEnabledCipherSuites()
method. Initially, a default set of cipher suites will be enabled on a new engine that represents the minimum suggested configuration. Each SSL/TLS/DTLS connection must have one client and one server, thus each endpoint must decide which role to assume. This choice determines who begins the handshaking process as well as which type of messages should be sent by each party. The method setUseClientMode(boolean)
configures the mode. Note that the default mode for a new SSLEngine
is provider-specific. Applications should set the mode explicitly before invoking other methods of the SSLEngine
. Once the initial handshaking has started, an SSLEngine
can not switch between client and server modes, even when performing renegotiations.
The ApplicationProtocol String
values returned by the methods in this class are in the network byte representation sent by the peer. The bytes could be directly compared, or converted to its Unicode String
format for comparison.
String networkString = sslEngine.getHandshakeApplicationProtocol(); byte[] bytes = networkString.getBytes(StandardCharsets.ISO_8859_1); // // Match using bytes: // // "http/1.1" (7-bit ASCII values same in UTF-8) // MEETEI MAYEK LETTERS "HUK UN I" (Unicode 0xabcd->0xabcf) // String HTTP1_1 = "http/1.1"; byte[] HTTP1_1_BYTES = HTTP1_1.getBytes(StandardCharsets.UTF_8); byte[] HUK_UN_I_BYTES = new byte[] { (byte) 0xab, (byte) 0xcd, (byte) 0xab, (byte) 0xce, (byte) 0xab, (byte) 0xcf}; if ((Arrays.compare(bytes, HTTP1_1_BYTES) == 0 ) || Arrays.compare(bytes, HUK_UN_I_BYTES) == 0) { ... } // // Alternatively match using string.equals() if we know the ALPN value // was encoded from aString
using a certain character set, // for exampleUTF-8
. The ALPN value must first be properly // decoded to a UnicodeString
before use. // String unicodeString = new String(bytes, StandardCharsets.UTF_8); if (unicodeString.equals(HTTP1_1) || unicodeString.equals("\uabcd\uabce\uabcf")) { ... }
Applications might choose to process delegated tasks in different threads. When an SSLEngine
is created, the current AccessControlContext
is saved. All future delegated tasks will be processed using this context: that is, all access control decisions will be made using the context captured at engine creation.
wrap()
and unwrap()
methods may execute concurrently of each other. For example:
synchronized (outboundLock) { sslEngine.wrap(src, dst); outboundQueue.put(dst); }As a corollary, two threads must not attempt to call the same method (either
wrap()
or unwrap()
) concurrently, because there is no way to guarantee the eventual packet ordering. Modifier | Constructor | Description |
---|---|---|
protected |
Constructor for an SSLEngine providing no hints for an internal session reuse strategy. |
|
protected |
Constructor for an SSLEngine . |
Modifier and Type | Method | Description |
---|---|---|
abstract void |
beginHandshake() |
Initiates handshaking (initial or renegotiation) on this SSLEngine. |
abstract void |
closeInbound() |
Signals that no more inbound network data will be sent to this SSLEngine . |
abstract void |
closeOutbound() |
Signals that no more outbound application data will be sent on this SSLEngine . |
String |
getApplicationProtocol() |
Returns the most recent application protocol value negotiated for this connection. |
abstract Runnable |
getDelegatedTask() |
Returns a delegated Runnable task for this SSLEngine . |
abstract String[] |
getEnabledCipherSuites() |
Returns the names of the SSL cipher suites which are currently enabled for use on this engine. |
abstract String[] |
getEnabledProtocols() |
Returns the names of the protocol versions which are currently enabled for use with this SSLEngine . |
abstract boolean |
getEnableSessionCreation() |
Returns true if new SSL sessions may be established by this engine. |
String |
getHandshakeApplicationProtocol() |
Returns the application protocol value negotiated on a SSL/TLS handshake currently in progress. |
BiFunction |
getHandshakeApplicationProtocolSelector() |
Retrieves the callback function that selects an application protocol value during a SSL/TLS/DTLS handshake. |
SSLSession |
getHandshakeSession() |
Returns the SSLSession being constructed during a SSL/TLS/DTLS handshake. |
abstract SSLEngineResult.HandshakeStatus |
getHandshakeStatus() |
Returns the current handshake status for this SSLEngine . |
abstract boolean |
getNeedClientAuth() |
Returns true if the engine will require client authentication. |
String |
getPeerHost() |
Returns the host name of the peer. |
int |
getPeerPort() |
Returns the port number of the peer. |
abstract SSLSession |
getSession() |
Returns the SSLSession in use in this SSLEngine . |
SSLParameters |
getSSLParameters() |
Returns the SSLParameters in effect for this SSLEngine. |
abstract String[] |
getSupportedCipherSuites() |
Returns the names of the cipher suites which could be enabled for use on this engine. |
abstract String[] |
getSupportedProtocols() |
Returns the names of the protocols which could be enabled for use with this SSLEngine . |
abstract boolean |
getUseClientMode() |
Returns true if the engine is set to use client mode when handshaking. |
abstract boolean |
getWantClientAuth() |
Returns true if the engine will request client authentication. |
abstract boolean |
isInboundDone() |
Returns whether unwrap(ByteBuffer, ByteBuffer) will accept any more inbound data messages. |
abstract boolean |
isOutboundDone() |
Returns whether wrap(ByteBuffer, ByteBuffer) will produce any more outbound data messages. |
abstract void |
setEnabledCipherSuites |
Sets the cipher suites enabled for use on this engine. |
abstract void |
setEnabledProtocols |
Set the protocol versions enabled for use on this engine. |
abstract void |
setEnableSessionCreation |
Controls whether new SSL sessions may be established by this engine. |
void |
setHandshakeApplicationProtocolSelector |
Registers a callback function that selects an application protocol value for a SSL/TLS/DTLS handshake. |
abstract void |
setNeedClientAuth |
Configures the engine to require client authentication. |
void |
setSSLParameters |
Applies SSLParameters to this engine. |
abstract void |
setUseClientMode |
Configures the engine to use client (or server) mode when handshaking. |
abstract void |
setWantClientAuth |
Configures the engine to request client authentication. |
SSLEngineResult |
unwrap |
Attempts to decode SSL/TLS/DTLS network data into a plaintext application data buffer. |
SSLEngineResult |
unwrap |
Attempts to decode SSL/TLS/DTLS network data into a sequence of plaintext application data buffers. |
abstract SSLEngineResult |
unwrap |
Attempts to decode SSL/TLS/DTLS network data into a subsequence of plaintext application data buffers. |
abstract SSLEngineResult |
wrap |
Attempts to encode plaintext bytes from a subsequence of data buffers into SSL/TLS/DTLS network data. |
SSLEngineResult |
wrap |
Attempts to encode plaintext bytes from a sequence of data buffers into SSL/TLS/DTLS network data. |
SSLEngineResult |
wrap |
Attempts to encode a buffer of plaintext application data into SSL/TLS/DTLS network data. |
protected SSLEngine()
SSLEngine
providing no hints for an internal session reuse strategy.protected SSLEngine(String peerHost, int peerPort)
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
.
peerHost
- the name of the peer hostpeerPort
- the port number of the peerpublic String getPeerHost()
Note that the value is not authenticated, and should not be relied upon.
public int getPeerPort()
Note that the value is not authenticated, and should not be relied upon.
public SSLEngineResult wrap(ByteBuffer src, ByteBuffer dst) throws SSLException
An invocation of this method behaves in exactly the same manner as the invocation:
engine.wrap(new ByteBuffer[] { src }, 0, 1, dst);
src
- a ByteBuffer
containing outbound application datadst
- a ByteBuffer
to hold outbound network dataSSLEngineResult
describing the result of this operation.SSLException
- A problem was encountered while processing the data that caused the SSLEngine
to abort. See the class description for more information on engine closure.ReadOnlyBufferException
- if the dst
buffer is read-only.IllegalArgumentException
- if either src
or dst
is null.IllegalStateException
- if the client/server mode has not yet been set.public SSLEngineResult wrap(ByteBuffer[] srcs, ByteBuffer dst) throws SSLException
An invocation of this method behaves in exactly the same manner as the invocation:
engine.wrap(srcs, 0, srcs.length, dst);
srcs
- an array of ByteBuffers
containing the outbound application datadst
- a ByteBuffer
to hold outbound network dataSSLEngineResult
describing the result of this operation.SSLException
- A problem was encountered while processing the data that caused the SSLEngine
to abort. See the class description for more information on engine closure.ReadOnlyBufferException
- if the dst
buffer is read-only.IllegalArgumentException
- if either srcs
or dst
is null, or if any element in srcs
is null.IllegalStateException
- if the client/server mode has not yet been set.public abstract SSLEngineResult wrap(ByteBuffer[] srcs, int offset, int length, ByteBuffer dst) throws SSLException
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/DTLS 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 ByteBuffer
s must not be the same.
See the class description for more information on engine closure.
srcs
- an array of ByteBuffers
containing the outbound application dataoffset
- The offset within the buffer array of the first buffer from which bytes are to be retrieved; it must be non-negative and no larger than srcs.length
length
- The maximum number of buffers to be accessed; it must be non-negative and no larger than srcs.length
- offset
dst
- a ByteBuffer
to hold outbound network dataSSLEngineResult
describing the result of this operation.SSLException
- A problem was encountered while processing the data that caused the SSLEngine
to abort. See the class description for more information on engine closure.IndexOutOfBoundsException
- if the preconditions on the offset
and length
parameters do not hold.ReadOnlyBufferException
- if the dst
buffer is read-only.IllegalArgumentException
- if either srcs
or dst
is null, or if any element in the srcs
subsequence specified is null.IllegalStateException
- if the client/server mode has not yet been set.public SSLEngineResult unwrap(ByteBuffer src, ByteBuffer dst) throws SSLException
An invocation of this method behaves in exactly the same manner as the invocation:
engine.unwrap(src, new ByteBuffer[] { dst }, 0, 1);
src
- a ByteBuffer
containing inbound network data.dst
- a ByteBuffer
to hold inbound application data.SSLEngineResult
describing the result of this operation.SSLException
- A problem was encountered while processing the data that caused the SSLEngine
to abort. See the class description for more information on engine closure.ReadOnlyBufferException
- if the dst
buffer is read-only.IllegalArgumentException
- if either src
or dst
is null.IllegalStateException
- if the client/server mode has not yet been set.public SSLEngineResult unwrap(ByteBuffer src, ByteBuffer[] dsts) throws SSLException
An invocation of this method behaves in exactly the same manner as the invocation:
engine.unwrap(src, dsts, 0, dsts.length);
src
- a ByteBuffer
containing inbound network data.dsts
- an array of ByteBuffer
s to hold inbound application data.SSLEngineResult
describing the result of this operation.SSLException
- A problem was encountered while processing the data that caused the SSLEngine
to abort. See the class description for more information on engine closure.ReadOnlyBufferException
- if any of the dst
buffers are read-only.IllegalArgumentException
- if either src
or dsts
is null, or if any element in dsts
is null.IllegalStateException
- if the client/server mode has not yet been set.public abstract SSLEngineResult unwrap(ByteBuffer src, ByteBuffer[] dsts, int offset, int length) throws SSLException
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/DTLS 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 ByteBuffer
s must not be the same.
The inbound network buffer, src
, 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/DTLS messages.
See the class description for more information on engine closure.
src
- a ByteBuffer
containing inbound network data.dsts
- an array of ByteBuffer
s to hold inbound application data.offset
- The offset within the buffer array of the first buffer from which bytes are to be transferred; it must be non-negative and no larger than dsts.length
.length
- The maximum number of buffers to be accessed; it must be non-negative and no larger than dsts.length
- offset
.SSLEngineResult
describing the result of this operation.SSLException
- A problem was encountered while processing the data that caused the SSLEngine
to abort. See the class description for more information on engine closure.IndexOutOfBoundsException
- If the preconditions on the offset
and length
parameters do not hold.ReadOnlyBufferException
- if any of the dst
buffers are read-only.IllegalArgumentException
- if either src
or dsts
is null, or if any element in the dsts
subsequence specified is null.IllegalStateException
- if the client/server mode has not yet been set.public abstract Runnable getDelegatedTask()
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.
Runnable
task, or null if none are available.public abstract void closeInbound() throws SSLException
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/DTLS data stream is reached. This ensures closure of the inbound side, and checks that the peer followed the SSL/TLS/DTLS 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.
SSLException
- if this engine has not received the proper SSL/TLS/DTLS close notification message from the peer.public abstract boolean isInboundDone()
unwrap(ByteBuffer, ByteBuffer)
will accept any more inbound data messages.SSLEngine
will not consume any more network data (and by implication, will not produce any more application data.)public abstract void closeOutbound()
SSLEngine
. This method is idempotent: if the outbound side has already been closed, this method does not do anything.
wrap(ByteBuffer, ByteBuffer)
should be called to flush any remaining handshake data.
public abstract boolean isOutboundDone()
wrap(ByteBuffer, 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.
SSLEngine
will not produce any more network datapublic abstract String[] getSupportedCipherSuites()
The returned array includes cipher suites from the list of standard cipher suite names in the JSSE Cipher Suite Names section of the Java Security Standard Algorithm Names Specification, and may also include other cipher suites that the provider supports.
public abstract String[] getEnabledCipherSuites()
Note that even if a suite is enabled, it may never be used. This can occur if the peer does not support it, or its use is restricted, or the requisite certificates (and private keys) for the suite are not available, or an anonymous suite is enabled but authentication is required.
The returned array includes cipher suites from the list of standard cipher suite names in the JSSE Cipher Suite Names section of the Java Security Standard Algorithm Names Specification, and may also include other cipher suites that the provider supports.
public abstract void setEnabledCipherSuites(String[] suites)
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.
Note that the standard list of cipher suite names may be found in the JSSE Cipher Suite Names section of the Java Security Standard Algorithm Names Specification. Providers may support cipher suite names not found in this list or might not use the recommended name for a certain cipher suite.
See getEnabledCipherSuites()
for more information on why a specific cipher suite may never be used on an engine.
suites
- Names of all the cipher suites to enableIllegalArgumentException
- when one or more of the ciphers named by the parameter is not supported, or when the parameter is null.public abstract String[] getSupportedProtocols()
SSLEngine
.public abstract String[] getEnabledProtocols()
SSLEngine
. Note that even if a protocol is enabled, it may never be used. This can occur if the peer does not support the protocol, or its use is restricted, or there are no enabled cipher suites supported by the protocol.
public abstract void setEnabledProtocols(String[] protocols)
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.
protocols
- Names of all the protocols to enable.IllegalArgumentException
- when one or more of the protocols named by the parameter is not supported or when the protocols parameter is null.public abstract SSLSession getSession()
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".
SSLSession
for this SSLEngine
public SSLSession getHandshakeSession()
SSLSession
being constructed during a SSL/TLS/DTLS handshake. TLS/DTLS 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 be used during TrustManager decisions, or the maximum TLS/DTLS 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.
SSLSession
currently being negotiated.UnsupportedOperationException
- if the underlying provider does not implement the operation.public abstract void beginHandshake() throws SSLException
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/DTLS 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
.
SSLException
- if a problem was encountered while signaling the SSLEngine
to begin a new handshake. See the class description for more information on engine closure.IllegalStateException
- if the client/server mode has not yet been set.public abstract SSLEngineResult.HandshakeStatus getHandshakeStatus()
SSLEngine
.SSLEngineResult.HandshakeStatus
.public abstract void setUseClientMode(boolean mode)
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.
mode
- true if the engine should start its handshaking in "client" modeIllegalArgumentException
- if a mode change is attempted after the initial handshake has begun.public abstract boolean getUseClientMode()
setUseClientMode(boolean)
is used to change the mode to true.public abstract void setNeedClientAuth(boolean need)
An engine's client authentication setting is one of the following:
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)
.
need
- set to true if client authentication is required, or false if no client authentication is desired.public abstract boolean getNeedClientAuth()
public abstract void setWantClientAuth(boolean want)
An engine's client authentication setting is one of the following:
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)
.
want
- set to true if client authentication is requested, or false if no client authentication is desired.public abstract boolean getWantClientAuth()
public abstract void setEnableSessionCreation(boolean flag)
flag
- true indicates that sessions may be created; this is the default. false indicates that an existing session must be resumedpublic abstract boolean getEnableSessionCreation()
public SSLParameters getSSLParameters()
public void setSSLParameters(SSLParameters params)
This means:
params.getCipherSuites()
is non-null, setEnabledCipherSuites()
is called with that value.params.getProtocols()
is non-null, setEnabledProtocols()
is called with that value.params.getNeedClientAuth()
or params.getWantClientAuth()
return true
, setNeedClientAuth(true)
and setWantClientAuth(true)
are called, respectively; otherwise setWantClientAuth(false)
is called.params.getServerNames()
is non-null, the engine will configure its server names with that value.params.getSNIMatchers()
is non-null, the engine will configure its SNI matchers with that value.params
- the parametersIllegalArgumentException
- if the setEnabledCipherSuites() or the setEnabledProtocols() call failspublic String getApplicationProtocol()
If supported by the underlying SSL/TLS/DTLS implementation, application name negotiation mechanisms such as RFC 7301 , the Application-Layer Protocol Negotiation (ALPN), can negotiate application-level values between peers.
UnsupportedOperationException
and performs no other action.String
if application protocols values will not be used, or a non-empty application protocol String
if a value was successfully negotiated.UnsupportedOperationException
- if the underlying provider does not implement the operation.public String getHandshakeApplicationProtocol()
Like getHandshakeSession()
, a connection may be in the middle of a handshake. The application protocol may or may not yet be available.
UnsupportedOperationException
and performs no other action.String
if application protocols values will not be used, or a non-empty application protocol String
if a value was successfully negotiated.UnsupportedOperationException
- if the underlying provider does not implement the operation.public void setHandshakeApplicationProtocolSelector(BiFunction<SSLEngine,List<String>,String> selector)
SSLParameters.setApplicationProtocols
and it supports the following type parameters: For example, the following call registers a callback function that examines the TLS handshake parameters and selects an application protocol name:
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());
});
SSLEngine
should be configured with parameters that are compatible with the application protocol selected by the callback function. For example, enabling a poor choice of cipher suites could result in no suitable application protocol. See SSLParameters
.UnsupportedOperationException
and performs no other action.selector
- the callback function, or null to disable the callback functionality.UnsupportedOperationException
- if the underlying provider does not implement the operation.public BiFunction<SSLEngine,List<String>,String> getHandshakeApplicationProtocolSelector()
setHandshakeApplicationProtocolSelector
for the function's type parameters.UnsupportedOperationException
and performs no other action.UnsupportedOperationException
- if the underlying provider does not implement the operation.
© 1993, 2023, Oracle and/or its affiliates. All rights reserved.
Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
Various third party code in OpenJDK is licensed under different licenses (see Debian package).
Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.
https://docs.oracle.com/en/java/javase/21/docs/api/java.base/javax/net/ssl/SSLEngine.html