ltm rule command MQTT payload

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

MQTT::payload
       Manipulate payload of MQTT PUBLISH message

SYNOPSIS
       MQTT::payload (('length') |
			      ('replace' CONTENT) |
			      ('prepend' CONTENT) |
			      ('append' CONTENT))?

DESCRIPTION
       This command can be used to manipulate payload of MQTT message.	This command is valid only for following MQTT
       message types:

	   PUBLISH

       Syntax

       MQTT::payload [ length | replace  | prepend  | append  ]

       MQTT::payload
	   * Returns the collected payload obtained as a result of a prior call to MQTT::collect.
	     This command should be called without an argument only from MQTT_CLIENT_DATA or MQTT_SERVER_DATA events.

       MQTT::payload length
	   * Returns the length of payload of MQTT PUBLISH message.
	     Make sure to call this method and call MQTT::collect only when payload length is not zero.

       MQTT::payload replace 
	   * Replace the entire payload of the MQTT PUBLISH message with specified .

       MQTT::payload prepend 
	   * Add the specified  to the beginning of the payload of MQTT PUBLISH message.

       MQTT::payload append 
	   * Add the specified  to the end of the collected payload of MQTT PUBLISH message.
	     For this command to work, MQTT::collect must be called prior to calling this.
	     This command should be called only from MQTT_CLIENT_DATA or MQTT_SERVER_DATA events.
	     Please note that in order to append the  at the end of payload, the MQTT::collect
	     must collect entire payload. If collect is partial, this command will append  to
	     the end of the data collected at the time this command is invoked. This can happen when
	     MQTT::collect is called with a length smaller than the payload length as the argument.

RETURN VALUE
       When called without an argument, this command returns the collected payload of MQTT PUBLISH message.

VALID DURING
       MQTT_CLIENT_INGRESS MQTT_CLIENT_DATA MQTT_SERVER_INGRESS MQTT_SERVER_DATA

EXAMPLES
	#Example: Redirect PUBLISH that has payloads with blocked keywords defined in
	#blacklisted_keywords_datagroup in first 200 bytes. Prepend a admin message in
	#the payload.
	#
	when MQTT_CLIENT_INGRESS {
	    set type [MQTT::type]
	    switch $type {
	       "PUBLISH" {
		  if { [class exists  blacklisted_keywords_datagroup] } {
		     MQTT::collect 200
		  }
	       }
	    }
	}

	when MQTT_CLIENT_DATA {
	   set type [MQTT::type]
	   switch $type {
	       "PUBLISH" {
		  set payload [MQTT::payload]
		  set found [class match $payload contains blacklisted_keywords_datagroup]
		  if { $found != "" } {
		     set topic [MQTT::topic]
		     MQTT::topic "/bigip/quarantined/$topic"
		     MQTT::payload prepend "!!!!!! QUARANTINED Message !!!!!!"
		  }
		  MQTT::release
	       }
	   }
	}

HINTS
SEE ALSO
CHANGE LOG
       @BIGIP-13.0.0 --First introduced the command.

BIG-IP						      2020-06-23					     iRule(1)