ltm rule event STREAM MATCHED

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



STREAM_MATCHED
       Triggered when a stream expression matches.

DESCRIPTION
       Triggered when a stream expression matches. This event can be used to
       skip or change the replacement target.

Examples
	## This example modifies the replacement string based so that only some
	matches are rewritten. Replace any http:// instance with https:// only
	if the original string is http://*example.com.

	when HTTP_RESPONSE {

	   # Disable the stream filter by default
	   STREAM::disable

	   # Check if response type is text
	   if {[HTTP::header value Content-Type] contains "text"}{

	      # Match any http:// instance and replace it with nothing
	      STREAM::expression {&http://.*?example\.com&}

	      # Enable the stream filter for this response only
	      STREAM::enable
	   }
	}
	when STREAM_MATCHED {
	   log local0. "[IP::client_addr]:[TCP::local_port]: matched: [STREAM::match], replaced with: [string map {http:// https://} [STREAM::match]]"
	   STREAM::replace "[string map {http:// https://} [STREAM::match]]"
	}


	Log output:
	Rule stream_expression_rule : 10.0.0.1:3413: matched: http://test.example.com, replaced with: https://test.example.com
	Rule stream_expression_rule : 10.0.0.1:3413: matched: http://example.com, replaced with: https://example.com


	## This example just reads the stream match in the STREAM_MATCHED event and adds a persistence record.

	# Look for the jsessionid string in response content and add a persistence record when it is found.
	# Using STREAM:: commands requires a STREAM profile be added to the virtual server.  Use a blank profile.
	# To force LTM to recalculate the Content-Length value, add a custom HTTP profile to the virtual server_addr
	#  with Chunking set to Rechunk.
	when HTTP_RESPONSE {

	   # Clear the jsessionid if it exists already on this TCP connection
	   if {[info exists jsessionid]}{
	      unset jsessionid
	   }

	   # Only look for the jsessionid in text responses
	   if {[HTTP::header value "Content-Type"] starts_with "text"}{

	      log local0. "[IP::client_addr]:[TCP::client_port]: Matched text, enabling stream filter"

	      # Because TCL doesn't support lookaheads, match the jsessionid string and value
	      # We'll parse out the value in STREAM_MATCHED
	      # Assume the jsessionid is 1 to 100 characters (terminated by a non-alphanumeric character).
	      STREAM::expression ;jsessionid=[A-Za-z0-9]{1,100}
	      STREAM::enable

	      # Enable the STREAM_MATCHED event as it could have been disabled if there was a prior
	      # response on this TCP connection
	      event STREAM_MATCHED enable

	   } else {

	      # Disable the stream filter as this wasn't a text response
	      log local0. "[IP::client_addr]:[TCP::client_port]: No Content-Type match, disabling stream filter"
	      STREAM::disable
	   }
	}
	when STREAM_MATCHED {

	   # Save the matched value (example: ;jsessionid=ABCDEF)
	   set jsessionid [STREAM::match]
	   log local0. "[IP::client_addr]:[TCP::client_port]: Matched: $jsessionid"

	   # STREAM::match shouldn't match a null string with the defined regex, but check anyhow
	   if {[string length $jsessionid]}{

	      # Get the jsessionid value (split ;jsessionid=ABCDEF on the equals sign)
	      set jsessionid [getfield $jsessionid "=" 2]

	      # Not sure why, but the parser doesn't allow the persist command.
	      # It works though, so hide the command from the parser
	      set persist_cmd "persist add uie $jsessionid"
	      log local0. "[IP::client_addr]:[TCP::client_port]: Parsed: $jsessionid \$persist_cmd: $persist_cmd"

	      eval $persist_cmd

	      # Assume the first match is the same as any other jsessionids, so stop checking for them
	      log local0. "[IP::client_addr]:[TCP::client_port]: Added persistence record. Exiting event for this response."
	      event STREAM_MATCHED disable
	   }
	}

	Log output:

	Rule persist_on_response_content_stream_rule : 1.2.3.4:2418: Matched text, enabling stream filter
	Rule persist_on_response_content_stream_rule : 1.2.3.4:2418: Matched: ;jsessionid=a111111111111111111z
	Rule persist_on_response_content_stream_rule : 1.2.3.4:2418: Parsed: a111111111111111111z $persist_cmd: persist add uie a111111111111111111z
	Rule persist_on_response_content_stream_rule : 1.2.3.4:2418: Added persistence record. Exiting event for this response.

HINTS
SEE ALSO
CHANGE LOG
       @BIGIP-9.2.0 --First introduced the event.



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