Module org.jnetpcap

Package org.jnetpcap

Class PcapHeader

java.lang.Object

org.jnetpcap.PcapHeader

public final class PcapHeader
extends Object

PcapHeader relies on preview features of the Java platform:

• PcapHeader refers to one or more preview APIs: MemorySegment.

Programs can only use PcapHeader when preview features are enabled.

Preview features may be removed in a future release, or upgraded to permanent features of the Java platform.

A Pcap packet header also called a descriptor that precedes each packet. The pcap header is supplied natively by libpcap library and PcapHeader can bind to native memory without copy to access its fields.

PcapHeader supplies vital information about the captured packet. These fields disclaim the length of the data capture and if a packet was truncated with snaplen parameter on the Pcap handle, the packet length as originally seen on the wire. Additionally a timestamp of the instant when the packet was captured.

Author:

Sly Technologies Inc, repos@slytechs.com

See Also:

• Pcap.LibraryPolicy.SYSTEM_PROPERTY_ABI

Constructor Summary

Constructors

Constructor	Description
PcapHeader(int tvSec, int tvUsec, int captureLength, int wireLength)	Instantiates a new pcap header.
PcapHeader(MemorySegmentPREVIEW mseg)	Instantiates a new pcap header.
PcapHeader(MemorySegmentPREVIEW mseg, boolean isSwapped)	Instantiates a new pcap header.
PcapHeader(MemorySegmentPREVIEW mseg, boolean isSwapped, boolean isCompactAbi)	Instantiates a new pcap header.
PcapHeader(ByteBuffer headerBuffer)	Instantiates a new pcap header.

Method Summary

Modifier and Type	Method	Description
MemorySegmentPREVIEW	asMemoryReference()	As memory reference.
MemorySegmentPREVIEW	asMemorySegment()	As memory segment.
int	captureLength()	Capture length.
static int	captureLength(MemorySegmentPREVIEW headerSegment)	Packet capture length for offline file capture.
static int	captureLength(MemorySegmentPREVIEW headerSegment, boolean isSwapped)	Packet capture length for offline file capture.
static int	captureLength(ByteBuffer headerBuffer)	Packet capture length.
static int	captureLength(ByteBuffer headerBuffer, boolean isSwapped)	Packet capture length for offline file capture.
int	headerLength()	The length of this header.
PcapHeader	setNanoTimePrecision(boolean nanoTime)	Sets a flag if the timestamp for this header is calculated using nanosecond or the default microsecond precision.
long	timestamp()	Timestamp with 32-bit seconds (MSB bits) and 32-bit usecs (LSB bits) from a base of January 1, 1970.
long	timestamp(boolean nanoTime)	Timestamp in either nano or milli second precision.
long	toEpochMilli()	To epoch milli.
long	toEpochMilli(boolean nanoTime)	To epoch milli.
String	toString()	To string.
long	tvSec()	Tv sec.
long	tvUsec()	Tv usec.
int	wireLength()	Wire length.
static int	wireLength(MemorySegmentPREVIEW headerSegment)	Packet wire length.
static int	wireLength(MemorySegmentPREVIEW headerSegment, boolean isSwapped)	Packet wire length for offline file capture.
static int	wireLength(ByteBuffer headerBuffer)	Packet wire length .
static int	wireLength(ByteBuffer headerBuffer, boolean isSwapped)	Packet wire length for offline file capture.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Details

PcapHeader

public PcapHeader(ByteBuffer headerBuffer)

Instantiates a new pcap header.

Parameters:

headerBuffer - the header buffer

PcapHeader

public PcapHeader(int tvSec,
 int tvUsec,
 int captureLength,
 int wireLength)

Instantiates a new pcap header.

Parameters:

tvSec - the tv sec

tvUsec - the tv usec

captureLength - the capture length

wireLength - the wire length

PcapHeader

public PcapHeader(MemorySegmentPREVIEW mseg)

Instantiates a new pcap header.

Parameters:

mseg - the struct pcap_pkthdr memory address.

PcapHeader

public PcapHeader(MemorySegmentPREVIEW mseg,
 boolean isSwapped)

Instantiates a new pcap header.

Parameters:

mseg - the struct pcap_pkthdr memory address.

isSwapped - the flag indicates that the header is referencing memory for an offline capture and that the header field byte may be swapped, as recorded based on the original capture system architecture.

PcapHeader

public PcapHeader(MemorySegmentPREVIEW mseg,
 boolean isSwapped,
 boolean isCompactAbi)

Instantiates a new pcap header.

Parameters:

mseg - the struct pcap_pkthdr memory address.

isSwapped - the flag indicates that the header is referencing memory for an offline capture and that the header field byte may be swapped, as recorded based on the original capture system architecture. *

isCompactAbi - if true, forces the pcap binary interface to use the compact form.

See Also:

• Pcap.LibraryPolicy.SYSTEM_PROPERTY_ABI

Method Details

captureLength

public static int captureLength(ByteBuffer headerBuffer)
                         throws PcapHeaderException.OutOfRangeException

Packet capture length.

Parameters:

headerBuffer - the buffer containing pcap header contents

Returns:

the number of packet bytes captured

Throws:

PcapHeaderException.OutOfRangeException - the out of range exception, typically indicates invalid ABI (Application Binary Interface) setting which is platform and offline capture file dependent

captureLength

public static int captureLength(ByteBuffer headerBuffer,
 boolean isSwapped)
                         throws PcapHeaderException.OutOfRangeException

Packet capture length for offline file capture.

Parameters:

headerBuffer - the buffer containing pcap header contents

isSwapped - for offline files which were captured according to the capturing system ABI, the bytes written maybe swapped for this system's architecture.

Returns:

the number of packet bytes captured

Throws:

PcapHeaderException.OutOfRangeException - the out of range exception, typically indicates invalid ABI (Application Binary Interface) setting which is platform and offline capture file dependent

captureLength

public static int captureLength(MemorySegmentPREVIEW headerSegment)
                         throws PcapHeaderException.OutOfRangeException

Packet capture length for offline file capture.

Parameters:

headerSegment - the memory segment containing pcap header contents

Returns:

the number of packet bytes captured

Throws:

PcapHeaderException.OutOfRangeException - the out of range exception, typically indicates invalid ABI (Application Binary Interface) setting which is platform and offline capture file dependent

captureLength

public static int captureLength(MemorySegmentPREVIEW headerSegment,
 boolean isSwapped)
                         throws PcapHeaderException.OutOfRangeException

Packet capture length for offline file capture.

Parameters:

headerSegment - the memory segment containing pcap header contents

isSwapped - for offline files which were captured according to the capturing system ABI, the bytes written maybe swapped for this system's architecture.

Returns:

the number of packet bytes captured

Throws:

PcapHeaderException.OutOfRangeException - the out of range exception, typically indicates invalid ABI (Application Binary Interface) setting which is platform and offline capture file dependent

wireLength

public static int wireLength(ByteBuffer headerBuffer)
                      throws PcapHeaderException.OutOfRangeException

Packet wire length .

Parameters:

headerBuffer - the buffer containing pcap header contents

Returns:

the number of packet bytes originally seen on the network wire/wireless before truncation due to "snaplen" parameter if set.

Throws:

PcapHeaderException.OutOfRangeException - the out of range exception, typically indicates invalid ABI (Application Binary Interface) setting which is platform and offline capture file dependent

wireLength

public static int wireLength(ByteBuffer headerBuffer,
 boolean isSwapped)
                      throws PcapHeaderException.OutOfRangeException

Packet wire length for offline file capture.

Parameters:

headerBuffer - the buffer containing pcap header contents

isSwapped - for offline files which were captured according to the capturing system ABI, the bytes written maybe swapped for this system's architecture.

Returns:

the number of packet bytes originally seen on the network wire/wireless before truncation due to "snaplen" parameter if set.

Throws:

PcapHeaderException.OutOfRangeException - the out of range exception, typically indicates invalid ABI (Application Binary Interface) setting which is platform and offline capture file dependent

wireLength

public static int wireLength(MemorySegmentPREVIEW headerSegment)
                      throws PcapHeaderException.OutOfRangeException

Packet wire length.

Parameters:

headerSegment - the memory segment containing pcap header contents

Returns:

the number of packet bytes originally seen on the network wire/wireless before truncation due to "snaplen" parameter if set.

Throws:

PcapHeaderException.OutOfRangeException - the out of range exception, typically indicates invalid ABI (Application Binary Interface) setting which is platform and offline capture file dependent

wireLength

public static int wireLength(MemorySegmentPREVIEW headerSegment,
 boolean isSwapped)
                      throws PcapHeaderException.OutOfRangeException

Packet wire length for offline file capture.

Parameters:

headerSegment - the memory segment containing pcap header contents

isSwapped - for offline files which were captured according to the capturing system ABI, the bytes written maybe swapped for this system's architecture.

Returns:

the number of packet bytes originally seen on the network wire/wireless before truncation due to "snaplen" parameter if set.

Throws:

PcapHeaderException.OutOfRangeException - the out of range exception, typically indicates invalid ABI (Application Binary Interface) setting which is platform and offline capture file dependent

asMemoryReference

public MemorySegmentPREVIEW asMemoryReference()

As memory reference.

Returns:

the memory address

asMemorySegment

public MemorySegmentPREVIEW asMemorySegment()

As memory segment.

Returns:

the memory segment

captureLength

public int captureLength()
                  throws PcapHeaderException.OutOfRangeException

Capture length.

Returns:

the int

Throws:

PcapHeaderException.OutOfRangeException - the out of range exception

headerLength

public int headerLength()

The length of this header.

Returns:

the length of this header in bytes.

setNanoTimePrecision

public PcapHeader setNanoTimePrecision(boolean nanoTime)

Sets a flag if the timestamp for this header is calculated using nanosecond or the default microsecond precision.

Parameters:

nanoTime - if true, a call to timestamp() or toEpochMilli() will use nano second precision

Returns:

this pcap header

timestamp

public long timestamp()
               throws PcapHeaderException

Timestamp with 32-bit seconds (MSB bits) and 32-bit usecs (LSB bits) from a base of January 1, 1970.

Returns:

the long

Throws:

PcapHeaderException - the pcap header exception

timestamp

public long timestamp(boolean nanoTime)
               throws PcapHeaderException

Timestamp in either nano or milli second precision.

Parameters:

nanoTime - if true, timestamp is returned with nano second precision, otherwise millis is returned

Returns:

the timestamp value as 64-bit long

Throws:

PcapHeaderException - the pcap header exception

toEpochMilli

public long toEpochMilli()
                  throws PcapHeaderException

To epoch milli.

Returns:

the long

Throws:

PcapHeaderException - the pcap header exception

toEpochMilli

public long toEpochMilli(boolean nanoTime)
                  throws PcapHeaderException

To epoch milli.

Parameters:

nanoTime - the nano time

Returns:

the long

Throws:

PcapHeaderException - the pcap header exception

toString

public String toString()

To string.

Overrides:

toString in class Object

Returns:

the string

See Also:

• Object.toString()

tvSec

public long tvSec()
           throws PcapHeaderException

Tv sec.

Returns:

the int

Throws:

PcapHeaderException - the pcap header exception

tvUsec

public long tvUsec()
            throws PcapHeaderException

Tv usec.

Returns:

the int

Throws:

PcapHeaderException - the pcap header exception

wireLength

public int wireLength()
               throws PcapHeaderException

Wire length.

Returns:

the int

Throws:

PcapHeaderException - the pcap header exception