ltm rule command TCP payload

iRule(1)		      BIG-IP TMSH Manual		      iRule(1)



TCP::payload
       Returns or changes the data collected by TCP::collect.

SYNOPSIS
       TCP::payload (LENGTH | (OFFSET LENGTH))?

       TCP::payload length

       TCP::payload replace OFFSET LENGTH TCP_PAYLOAD

DESCRIPTION
       Returns the accumulated TCP data content, or replaces collected payload
       with the specified data.

       Syntax

       TCP::payload []

	    * Returns the accumulated TCP data content. If  is specified,
	      and more than  bytes are available, only the first 
	      bytes of collected data are returned.

       TCP::payload replace   

	    * Replaces  bytes of the collected payload data starting at
	       with the given .

       TCP::payload length

	    * Returns the amount of accumulated TCP data content in bytes.

	  Note: Currently, iRules usually treats binary data in TCL variables as
	  UTF-8 strings. Therefore, care must be taken when processing binary TCP
	  payloads. In particular, do not assign the result of TCP::payload to a
	  variable if non-text data should be processed literally. See the third
	  example below for a way to do a binary search-and-replace in a
	  TCP::payload. TCL variables explicitly created as binary data (e.g. via
	  the binary format command) are not treated as UTF-8 strings. There is
	  an outstanding enhancement request (tracked as CR47762 / BZ273220) to
	  treat TCL variables as binary data (rather than UTF-8 strings) as
	  appropriate.

RETURN VALUE
VALID DURING
       CLIENT_ACCEPTED, CLIENT_CLOSED, CLIENT_DATA, SERVER_CLOSED,
       SERVER_CONNECTED, SERVER_DATA, SIP_REQUEST, SIP_REQUEST_SEND,
       SIP_RESPONSE, STREAM_MATCHED

EXAMPLES
	when CLIENT_ACCEPTED {
	  TCP::collect 15
	}
	when CLIENT_DATA {
	  if { [TCP::payload 15] contains "XYZ" } {
	     pool xyz_servers
	  } else {
	     pool web_servers
	 }
	 TCP::release
	}


	when CLIENT_ACCEPTED {
	  TCP::collect
	}
	when CLIENT_DATA {
	  # empty payload entirely so there is no packet to send to the server
	  TCP::payload replace 0 [TCP::payload length] ""

	  # craft a string to hold our	packet data, 0x01 0x00 0x00 0x00 0x02 0x00 0x000x00 0x03 0x00 0x00 0x00
	  set packetdata [binary format i1i1i1 1 2 3 ]

	  # then fill payload with our own data from arbitrary length string called packetdata to send to the server
	  # this actually inserts it at the start of the packet, but because we emptiedthe packet above it becomes the new packet
	  TCP::payload replace 0 0 $packetdata

	  # release the payload to the server
	  TCP::release

	  # set up to grab the next packet
	  TCP::collect
	}


	when CLIENT_ACCEPTED {
	  TCP::collect
	}
	when CLIENT_DATA {
	  #
	  # Do a regex search and replace of binary TCP data
	  #
	  if { [regexp -indices "\x61\x62\x63\x64\x65\x66" [TCP::payload] firstmatch] }{
	    set matchlen [expr [lindex $firstmatch 1] - [lindex $firstmatch 0] + 1]
	    set replacement [binary format c* {97 98 99 0 100 101 102}]
	    TCP::payload replace [lindex $firstmatch 0] $matchlen $replacement
	    TCP::release
	  }
	}

HINTS
SEE ALSO
CHANGE LOG
       @BIGIP-9.0.0 --First introduced the command.



BIG-IP				  2017-01-31			      iRule(1)