Module org.jnetpcap

Package org.jnetpcap.internal

Class PcapForeignInitializer

java.lang.Object

org.jnetpcap.internal.ForeignInitializer<PcapForeignDowncall,PcapException>

org.jnetpcap.internal.PcapForeignInitializer

All Implemented Interfaces:

AutoCloseable

public class PcapForeignInitializer
extends ForeignInitializer<PcapForeignDowncall,PcapException>

Pcap specific ForeignInitializer used to facilitate loading native libary symbols and making of 'downcall' and 'upcall' function calls.

Author:

Sly Technologies Inc, repos@slytechs.com, mark

Nested Class Summary

Nested classes/interfaces inherited from class org.jnetpcap.internal.ForeignInitializer

ForeignInitializer.CType, ForeignInitializer.DowncallSupplier<T extends ForeignDowncall<?>>, ForeignInitializer.MethodHandleLookup, ForeignInitializer.MissingSymbolsPolicy

Field Summary

Fields

Modifier and Type	Field	Description
static final Appendable	DEFAULT_LOGGING_OUTPUT	The Constant which defines the default logging output which discards all of its input.

Constructor Summary

Constructors

Constructor	Description
PcapForeignInitializer(Class<?> initializerClass)	Instantiates a new pcap foreign initializer.

Method Summary

Modifier and Type	Method	Description
static Appendable	getLogginOutput()	Gets the loggin output.
static Pcap.LibraryPolicy	getPolicy()	Gets the default missing symbols policy.
static boolean	loadNativePcapLibrary(boolean ignoreErrors)	Load native pcap library, or one of its derivatives.
static void	setLoggingOutput(Appendable out)	Sets the logging output produced by the default missing symbols policy receiver.
static void	setPolicy(Pcap.LibraryPolicy newPolicy)	Sets the default missing native symbols policy.

Methods inherited from class org.jnetpcap.internal.ForeignInitializer

close, downcall, downcall, getName, makeAccessible, setMissingSymbolsPolicy, setName, upcall, upcallStatic, upcallStatic, upcallVirtual

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

DEFAULT_LOGGING_OUTPUT

public static final Appendable DEFAULT_LOGGING_OUTPUT

The Constant which defines the default logging output which discards all of its input.

Constructor Details

PcapForeignInitializer

public PcapForeignInitializer(Class<?> initializerClass)

Instantiates a new pcap foreign initializer.

Parameters:

initializerClass - the initializer class

Method Details

getLogginOutput

public static Appendable getLogginOutput()

Gets the loggin output.

Returns:

the loggin output

getPolicy

public static Pcap.LibraryPolicy getPolicy()

Gets the default missing symbols policy.

Returns:

the default missing symbols policy

loadNativePcapLibrary

public static boolean loadNativePcapLibrary(boolean ignoreErrors)
                                     throws ExceptionInInitializerError

Load native pcap library, or one of its derivatives. The defaults for the native library loading procedure, define a list of possible pcap library undecorated names such as 'wpcap,npcap,pcap' and utilize the relative System.loadLibrary(String) to search for the shared object/native library.

By specifying various system properties on the java command line, you can redefine how, where and what to look for when loading the native library.

The following properties are used in a search in the following order:

"java.library.path":

Defines directories where the native library will searched for.

"org.jnetpcap.libpcap.file":

Defines an absolute directory and decorated filename path to load the native library using

invalid @link

{@link System.#load(String)

} system call.

"org.jnetpcap.libpcap.filename":

Defines a decorated filename only of the native library. The decorated filename will be appended to the "java.library.path" and an absolute library load call will be attempted System.load(String).

"org.jnetpcap.libpcap.names":

A comma separated list of undecorated library names. Each of the undecorated names in the list will be attempted to load using System.loadLibrary(String) combined with the "java.library.path" property value.

"org.jnetpcap.so.extensions":

Lastly, as a long-shot attempt, a list of absolute files will be built by combining all the property values given, with fully decorated filenames which utilize the provided extensions, to try and locate the native library on the platform. The default extension list are defined as "so,dylib". Each one will be tried in turn.

Parameters:

ignoreErrors - if true, no errors will be thrown but a false flag will be returned

Returns:

true, if pcap library is loaded otherwise false

Throws:

ExceptionInInitializerError - the exception in initializer error

See Also:

• Pcap.LibraryPolicy.SYSTEM_PROPERTY_JAVA_LIBRARY_PATH
• Pcap.LibraryPolicy.SYSTEM_PROPERTY_LIBPCAP_FILE
• Pcap.LibraryPolicy.SYSTEM_PROPERTY_LIBPCAP_FILENAME
• Pcap.LibraryPolicy.SYSTEM_PROPERTY_LIBPCAP_NAMES
• Pcap.LibraryPolicy.SYSTEM_PROPERTY_SO_EXTENSIONS
• Pcap.LibraryPolicy.SYSTEM_PROPERTY_SO_IGNORE_LOAD_ERRORS

setPolicy

public static void setPolicy(Pcap.LibraryPolicy newPolicy)

Sets the default missing native symbols policy.

Missing symbols policy is executed during early/static initialization phase of Pcap library. The policy object receives a list of symbols both for 'downcall' and 'upcall' symbols which were not found during loading of the native pcap libarary. The ForeignInitializer creates stubs for each missing symbol, that when called at runtime will throw a safe exception. A missing symbols policy can intercept missing symbols during initialization phase and if so desired can throw an appropriate exception, halting any further initialization. A different policy might simply log an error using application's logger.

Parameters:

newPolicy - the new default missing symbols policy

See Also:

• setLoggingOutput(Appendable)

setLoggingOutput

public static void setLoggingOutput(Appendable out)

Sets the logging output produced by the default missing symbols policy receiver. By default the output is sent to PrintWriter.nullWriter() which discards all output. You can set another output consumer or override the policy using setPolicy(LibraryPolicy).

Parameters:

out - the new logging output

See Also:

• setPolicy(LibraryPolicy)