PcapWriteHandler (Netty API Reference (4.1.53.Final))

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, java.io.Closeable, java.lang.AutoCloseable
```
public final class PcapWriteHandler
extends ChannelDuplexHandler
implements java.io.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(java.io.OutputStream outputStream)` Create new `PcapWriteHandler` Instance.
`PcapWriteHandler(java.io.OutputStream outputStream, boolean captureZeroByte, boolean writePcapGlobalHeader)` Create new `PcapWriteHandler` Instance

Method Summary

All Methods Instance Methods Concrete Methods
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, java.lang.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, java.lang.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, java.lang.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(java.io.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:
    
    java.lang.NullPointerException - If OutputStream is null then we'll throw an NullPointerException
  - PcapWriteHandler
```
public PcapWriteHandler(java.io.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:
    
    java.lang.NullPointerException - If OutputStream is null then we'll throw an NullPointerException
- Method Detail
  - channelActive
```
public void channelActive(ChannelHandlerContext ctx)
                   throws java.lang.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:
    
    java.lang.Exception
  - channelRead
```
public void channelRead(ChannelHandlerContext ctx,
                        java.lang.Object msg)
                 throws java.lang.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:
    
    java.lang.Exception
  - write
```
public void write(ChannelHandlerContext ctx,
                  java.lang.Object msg,
                  ChannelPromise promise)
           throws java.lang.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:
    
    java.lang.Exception - thrown if an error occurs
  - handlerRemoved
```
public void handlerRemoved(ChannelHandlerContext ctx)
                    throws java.lang.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:
    
    java.lang.Exception
  - exceptionCaught
```
public void exceptionCaught(ChannelHandlerContext ctx,
                            java.lang.Throwable cause)
                     throws java.lang.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:
    
    java.lang.Exception
  - close
```
public void close()
           throws java.io.IOException
```
    Close PcapWriter and OutputStream.
    
    Note: Calling this method does not close PcapWriteHandler. Only Pcap Writes are closed.
    
    Specified by:
    
    close in interface java.io.Closeable
    
    Specified by:
    
    close in interface java.lang.AutoCloseable
    
    Throws:
    
    java.io.IOException - If OutputStream.close() throws an exception

Class PcapWriteHandler

Nested Class Summary

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

Constructor Summary

Method Summary

Methods inherited from class io.netty.channel.ChannelDuplexHandler

Methods inherited from class io.netty.channel.ChannelInboundHandlerAdapter

Methods inherited from class io.netty.channel.ChannelHandlerAdapter

Methods inherited from class java.lang.Object

Methods inherited from interface io.netty.channel.ChannelHandler

Constructor Detail

PcapWriteHandler

PcapWriteHandler

Method Detail

channelActive

channelRead

write

handlerRemoved

exceptionCaught

close