io.netty.handler.pcap

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/interfaces inherited from interface io.netty.channel.ChannelHandler

ChannelHandler.Sharable

Constructor Summary

Constructors

Constructor and Description
PcapWriteHandler(OutputStream outputStream) Create new PcapWriteHandler Instance.
PcapWriteHandler(OutputStream outputStream, boolean captureZeroByte, boolean writePcapGlobalHeader) Create new PcapWriteHandler Instance

Method Summary

Modifier and Type	Method and Description
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.
void	write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) Calls ChannelOutboundInvoker.write(Object, ChannelPromise) to forward to the next ChannelOutboundHandler in the ChannelPipeline.

Methods inherited from class io.netty.channel.ChannelDuplexHandler

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

Methods inherited from class io.netty.channel.ChannelInboundHandlerAdapter

channelInactive, channelReadComplete, channelRegistered, channelUnregistered, channelWritabilityChanged, userEventTriggered

Methods inherited from class io.netty.channel.ChannelHandlerAdapter

ensureNotSharable, handlerAdded, isSharable

Methods inherited from class java.lang.Object

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

Methods inherited from interface io.netty.channel.ChannelHandler

handlerAdded

Constructor Detail

PcapWriteHandler

public PcapWriteHandler(OutputStream outputStream)

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

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

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 Detail

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

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 Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException - If OutputStream.close() throws an exception