org.jnetpcap.protocol.tcpip
Class Tcp.Timestamp

java.lang.Object
  org.jnetpcap.nio.JMemory
      org.jnetpcap.nio.JBuffer
          org.jnetpcap.packet.JHeader
              org.jnetpcap.packet.JSubHeader<Tcp>
                  org.jnetpcap.protocol.tcpip.Tcp.TcpOption
                      org.jnetpcap.protocol.tcpip.Tcp.Timestamp

All Implemented Interfaces:

JPayloadAccessor

Enclosing class:

Tcp

@Header(id=8)
public static class Tcp.Timestamp
extends Tcp.TcpOption

TCP timestamps, defined in RFC 1323, help TCP compute the round-trip time between the sender and receiver. Timestamp options include a 4-byte timestamp value, where the sender inserts its current value of its timestamp clock, and a 4-byte echo reply timestamp value, where the receiver generally inserts the most recent timestamp value that it has received. The sender uses the echo reply timestamp in an acknowledgment to compute the total elapsed time since the acknowledged segment was sent.[2]

TCP timestamps are also used to help in the case where TCP sequence numbers encounter their 232 bound and "wrap around" the sequence number space. This scheme is known as Protect Against Wrapped Sequence numbers, or PAWS (see RFC 1323 for details). Furthermore, the Eifel detection algorithm, defined in RFC 3522, which detects unnecessary loss recovery requires TCP timestamps.

Author:

Mark Bednarczyk, Sly Technologies, Inc.

Nested Class Summary

Nested classes/interfaces inherited from class org.jnetpcap.protocol.tcpip.Tcp.TcpOption

Tcp.TcpOption.OptionCode

Nested classes/interfaces inherited from class org.jnetpcap.packet.JHeader

JHeader.State

Nested classes/interfaces inherited from class org.jnetpcap.nio.JMemory

JMemory.Type

Field Summary

Fields inherited from class org.jnetpcap.packet.JHeader

annotatedHeader, BYTE, EMPTY_HEADER_ARRAY, isSubHeader, packet, state

Fields inherited from class org.jnetpcap.nio.JMemory

JNETPCAP_LIBRARY_NAME, MAX_DIRECT_MEMORY_DEFAULT, POINTER

Constructor Summary

Tcp.Timestamp()

Method Summary

long	tsecr() This field is only valid if the ACK bit is set in the TCP header.
void	tsecr(long value) Sets the field's value.
long	tsval() This field contains the current value of the timestamp clock of the TCP sending the option (32 bits).
void	tsval(long value) Sets the field's value.

Methods inherited from class org.jnetpcap.protocol.tcpip.Tcp.TcpOption

code, code, length, length, lengthCheck, lengthDescription

Methods inherited from class org.jnetpcap.packet.JSubHeader

getLength, getOffset, getParent, setLength, setOffset, setParent

Methods inherited from class org.jnetpcap.packet.JHeader

decode, decodeHeader, getAnnotatedHeader, getDescription, getFields, getGap, getGapLength, getGapOffset, getHeader, getHeaderLength, getHeaderOffset, getId, getIndex, getName, getNextHeaderId, getNextHeaderOffset, getNicname, getPacket, getPayload, getPayloadLength, getPayloadOffset, getPostfix, getPostfixLength, getPostfixOffset, getPrefix, getPrefixLength, getPrefixOffset, getPreviousHeaderId, getPreviousHeaderOffset, getState, getSubHeaders, hasDescription, hasGap, hasNextHeader, hasPayload, hasPostfix, hasPrefix, hasPreviousHeader, hasSubHeaders, isFragmented, isGapTruncated, isHeaderTruncated, isPayloadTruncated, isPostfixTruncated, isPrefixTruncated, peer, peer, peerPayloadTo, setPacket, setSubHeaders, sizeof, toString, transferPayloadTo, transferPayloadTo, transferPayloadTo, validateHeader

Methods inherited from class org.jnetpcap.nio.JBuffer

findUTF8String, getByte, getByteArray, getByteArray, getByteArray, getDouble, getFloat, getInt, getLong, getShort, getUByte, getUInt, getUShort, getUTF8Char, getUTF8String, getUTF8String, getUTF8String, getUTF8String, isReadonly, order, order, peer, peer, peer, peer, setByte, setByteArray, setByteBuffer, setDouble, setFloat, setInt, setLong, setShort, setShort0, setUByte, setUInt, setUShort, transferFrom, transferFrom, transferFrom, transferTo, transferTo, transferTo

Methods inherited from class org.jnetpcap.nio.JMemory

availableDirectMemory, check, cleanup, createReference, isInitialized, isJMemoryBasedOwner, isOwner, maxDirectMemory, peer, reservedDirectMemory, setSize, size, softDirectMemory, toDebugString, toHexdump, toHexdump, totalActiveAllocated, totalAllocateCalls, totalAllocated, totalAllocatedSegments0To255Bytes, totalAllocatedSegments256OrAbove, totalDeAllocateCalls, totalDeAllocated, transferFrom, transferFrom, transferFromDirect, transferOwnership, transferTo, transferTo, transferTo, transferTo, transferTo, transferTo0

Methods inherited from class java.lang.Object

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

Constructor Detail

Tcp.Timestamp

public Tcp.Timestamp()

Method Detail

tsecr

@Field(offset=48,
       length=32)
public long tsecr()

This field is only valid if the ACK bit is set in the TCP header. If it is valid, it echos a timestamp value that was sent by the remote TCP in the TSval field of a Timestamps option. When TSecr is not valid, its value must be zero. The TSecr value will generally be from the most recent Timestamp option that was received; A TCP may send the Timestamp option in an initial SYN segment (i.e., segment containing a SYN bit and no ACK bit), and may send a TSopt in other segments only if it received a TSopt in the initial SYN segment for the connection.

Returns:

timestamp value

tsecr

public void tsecr(long value)

Sets the field's value.

Parameters:

value - new field value

tsval

@Field(offset=16,
       length=32)
public long tsval()

This field contains the current value of the timestamp clock of the TCP sending the option (32 bits).

Returns:

field's value

tsval

public void tsval(long value)

Sets the field's value.

Parameters:

value - new field value