Class PcapWriteHandler

java.lang.Object

io.netty.channel.ChannelHandlerAdapter

io.netty.channel.ChannelInboundHandlerAdapter

io.netty.channel.ChannelDuplexHandler

io.netty.handler.pcap.PcapWriteHandler

All Implemented Interfaces:

ChannelHandler, ChannelInboundHandler, ChannelOutboundHandler, Closeable, AutoCloseable

public final class PcapWriteHandler
extends ChannelDuplexHandler
implements Closeable

PcapWriteHandler captures ByteBuf from SocketChannel / ServerChannel or DatagramPacket and writes it into Pcap OutputStream.

Things to keep in mind when using PcapWriteHandler with TCP:

• Whenever ChannelInboundHandlerAdapter.channelActive(ChannelHandlerContext) is called, a fake TCP 3-way handshake (SYN, SYN+ACK, ACK) is simulated as new connection in Pcap.
• Whenever ChannelHandlerAdapter.handlerRemoved(ChannelHandlerContext) is called, a fake TCP 3-way handshake (FIN+ACK, FIN+ACK, ACK) is simulated as connection shutdown in Pcap.
• Whenever ChannelInboundHandlerAdapter.exceptionCaught(ChannelHandlerContext, Throwable) is called, a fake TCP RST is sent to simulate connection Reset in Pcap.
• ACK is sent each time data is send / received.
• Zero Length Data Packets can cause TCP Double ACK error in Wireshark. To tackle this, set captureZeroByte to false.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static final class	PcapWriteHandler.Builder	Builder for PcapWriteHandler

Nested classes/interfaces inherited from interface ChannelHandler

ChannelHandler.Sharable

Constructor Summary

Constructors

Constructor	Description
PcapWriteHandler(OutputStream outputStream)	Deprecated. Use PcapWriteHandler.Builder instead.
PcapWriteHandler(OutputStream outputStream, boolean captureZeroByte, boolean writePcapGlobalHeader)	Deprecated. Use PcapWriteHandler.Builder instead.

Method Summary

Modifier and Type	Method	Description
static PcapWriteHandler.Builder	builder()
void	channelActive(ChannelHandlerContext ctx)	Calls ChannelHandlerContext.fireChannelActive() to forward to the next ChannelInboundHandler in the ChannelPipeline.
void	channelRead(ChannelHandlerContext ctx, Object msg)	Calls ChannelHandlerContext.fireChannelRead(Object) to forward to the next ChannelInboundHandler in the ChannelPipeline.
void	close()	Close PcapWriter and OutputStream.
void	exceptionCaught(ChannelHandlerContext ctx, Throwable cause)	Calls ChannelHandlerContext.fireExceptionCaught(Throwable) to forward to the next ChannelHandler in the ChannelPipeline.
void	handlerRemoved(ChannelHandlerContext ctx)	Do nothing by default, sub-classes may override this method.
boolean	isWriting()	Returns true if the PcapWriteHandler is currently writing packets to the OutputStream else returns false.
void	pause()	Pause the PcapWriteHandler from writing packets to the OutputStream.
void	resume()	Resume the PcapWriteHandler to writing packets to the OutputStream.
String	toString()
void	write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise)	Calls ChannelOutboundInvoker.write(Object, ChannelPromise) to forward to the next ChannelOutboundHandler in the ChannelPipeline.
static void	writeGlobalHeader(OutputStream outputStream)	Writes the Pcap Global Header to the provided OutputStream

Methods inherited from class ChannelDuplexHandler

bind, close, connect, deregister, disconnect, flush, read

Methods inherited from class ChannelInboundHandlerAdapter

channelInactive, channelReadComplete, channelRegistered, channelUnregistered, channelWritabilityChanged, userEventTriggered

Methods inherited from class ChannelHandlerAdapter

ensureNotSharable, handlerAdded, isSharable

Methods inherited from class Object

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

Methods inherited from interface ChannelHandler

handlerAdded

Constructor Details

PcapWriteHandler

@Deprecated
public PcapWriteHandler(OutputStream outputStream)

Deprecated.

Use PcapWriteHandler.Builder instead.

Create new PcapWriteHandler Instance. captureZeroByte is set to false and writePcapGlobalHeader is set to true.

Parameters:

outputStream - OutputStream where Pcap data will be written. Call close() to close this OutputStream.

Throws:

NullPointerException - If OutputStream is null then we'll throw an NullPointerException

PcapWriteHandler

@Deprecated
public PcapWriteHandler(OutputStream outputStream,
 boolean captureZeroByte,
 boolean writePcapGlobalHeader)

Deprecated.

Use PcapWriteHandler.Builder instead.

Create new PcapWriteHandler Instance

Parameters:

outputStream - OutputStream where Pcap data will be written. Call close() to close this OutputStream.

captureZeroByte - Set to true to enable capturing packets with empty (0 bytes) payload. Otherwise, if set to false, empty packets will be filtered out.

writePcapGlobalHeader - Set to true to write Pcap Global Header on initialization. Otherwise, if set to false, Pcap Global Header will not be written on initialization. This could when writing Pcap data on a existing file where Pcap Global Header is already present.

Throws:

NullPointerException - If OutputStream is null then we'll throw an NullPointerException

Method Details

writeGlobalHeader

public static void writeGlobalHeader(OutputStream outputStream)
                              throws IOException

Writes the Pcap Global Header to the provided OutputStream

Parameters:

outputStream - OutputStream where Pcap data will be written.

Throws:

IOException - if there is an error writing to the OutputStream

channelActive

public void channelActive(ChannelHandlerContext ctx)
                   throws Exception

Description copied from class: ChannelInboundHandlerAdapter

Calls ChannelHandlerContext.fireChannelActive() to forward to the next ChannelInboundHandler in the ChannelPipeline. Sub-classes may override this method to change behavior.

Specified by:

channelActive in interface ChannelInboundHandler

Overrides:

channelActive in class ChannelInboundHandlerAdapter

Throws:

Exception

channelRead

public void channelRead(ChannelHandlerContext ctx,
 Object msg)
                 throws Exception

Description copied from class: ChannelInboundHandlerAdapter

Calls ChannelHandlerContext.fireChannelRead(Object) to forward to the next ChannelInboundHandler in the ChannelPipeline. Sub-classes may override this method to change behavior.

Specified by:

channelRead in interface ChannelInboundHandler

Overrides:

channelRead in class ChannelInboundHandlerAdapter

Throws:

Exception

write

public void write(ChannelHandlerContext ctx,
 Object msg,
 ChannelPromise promise)
           throws Exception

Description copied from class: ChannelDuplexHandler

Calls ChannelOutboundInvoker.write(Object, ChannelPromise) to forward to the next ChannelOutboundHandler in the ChannelPipeline. Sub-classes may override this method to change behavior.

Specified by:

write in interface ChannelOutboundHandler

Overrides:

write in class ChannelDuplexHandler

Parameters:

ctx - the ChannelHandlerContext for which the write operation is made

msg - the message to write

promise - the ChannelPromise to notify once the operation completes

Throws:

Exception - thrown if an error occurs

handlerRemoved

public void handlerRemoved(ChannelHandlerContext ctx)
                    throws Exception

Description copied from class: ChannelHandlerAdapter

Do nothing by default, sub-classes may override this method.

Specified by:

handlerRemoved in interface ChannelHandler

Overrides:

handlerRemoved in class ChannelHandlerAdapter

Throws:

Exception

exceptionCaught

public void exceptionCaught(ChannelHandlerContext ctx,
 Throwable cause)
                     throws Exception

Description copied from class: ChannelInboundHandlerAdapter

Calls ChannelHandlerContext.fireExceptionCaught(Throwable) to forward to the next ChannelHandler in the ChannelPipeline. Sub-classes may override this method to change behavior.

Specified by:

exceptionCaught in interface ChannelHandler

Specified by:

exceptionCaught in interface ChannelInboundHandler

Overrides:

exceptionCaught in class ChannelInboundHandlerAdapter

Throws:

Exception

isWriting

public boolean isWriting()

Returns true if the PcapWriteHandler is currently writing packets to the OutputStream else returns false.

pause

public void pause()

Pause the PcapWriteHandler from writing packets to the OutputStream.

resume

public void resume()

Resume the PcapWriteHandler to writing packets to the OutputStream.

toString

public String toString()

Overrides:

toString in class Object

close

public void close()
           throws IOException

Close PcapWriter and OutputStream.

Note: Calling this method does not close PcapWriteHandler. Only Pcap Writes are closed.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Throws:

IOException - If OutputStream.close() throws an exception

builder

public static PcapWriteHandler.Builder builder()