Forum Discussion

steve_michaels's avatar
steve_michaels
Icon for Cirrus rankCirrus
Nov 08, 2021

iRule script injection and chunked Response page issue

We are using a modified version of this iRule: https://devcentral.f5.com/s/articles/google-analytics-script-injection-911

(See our iRule below) to inject a script into HTTP Responses. This iRule works fine for unchunked HTTP Response pages.

However we have some Response pages returned by the backend server that are chunked and this iRule fails. For those pages, logging shows

this Out of bounds error from the iRule:

 

Nov 1 10:48:39 xxxxxxx.jhuapl.edu err tmm[19381]: 01220001:3: TCL error: /Common/xxxCUI <HTTP_RESPONSE_DATA> - Out of bounds (line 1)    invoked from within "HTTP::payload replace 0 $content_length [string map [list $search "[subst -nocommands -nobackslashes [ifile get cui]]</body>"] [HTTP::payload]]"

 

  • - We believe we’re getting the error above because content length doesn’t exist in our chunked responses, so it’s getting set to 1000000 and we’re getting an out of bounds on payloads that are shorter than that.
  • - We tried setting the replace length to be that of the payload length, but then it doesn’t seem to “rechunk” the response correctly and parts seem to be missing.
  • - We’ve tried doing a Stream replace with an expression, but it doesn’t find and replace the content we’re targeting.

 

Any ideas on how to handle this issue / use case are appreciated.

BigIP version = 15.1.2.1

Thanks

-Steve M

 

application delivery
iRules
  • Dario_Garrido's avatar
    Dario_Garrido
    Nov 09, 2021

    Hello Steve.

    Try to downgrade your HTTP connection in order to avoid "Transfer-Encoding: chunked"

    when HTTP_REQUEST {
	HTTP::header remove "Accept-Encoding"
	if { [HTTP::version] eq "1.1" } {
		if { [HTTP::header is_keepalive] } {
			HTTP::header replace "Connection" "Keep-Alive"
		}
		HTTP::version "1.0"
	}
}

    Regards,

    Dario.

  • Dario_Garrido's avatar
    Dario_Garrido
    Icon for MVP rankMVP
    Nov 09, 2021

    Hello Steve.

    Try to downgrade your HTTP connection in order to avoid "Transfer-Encoding: chunked"

    when HTTP_REQUEST {
	HTTP::header remove "Accept-Encoding"
	if { [HTTP::version] eq "1.1" } {
		if { [HTTP::header is_keepalive] } {
			HTTP::header replace "Connection" "Keep-Alive"
		}
		HTTP::version "1.0"
	}
}

    Regards,

    Dario.

  • steve_michaels's avatar
    steve_michaels
    Icon for Cirrus rankCirrus
    Nov 12, 2021

    @Dario - Thanks very much for that suggestion. It worked for our use case. High-5 to you for that help!

    -Steve

    • Dario_Garrido's avatar
      Dario_Garrido
      Icon for MVP rankMVP
      Nov 13, 2021

      Great to hear that your issue is solved now.

      Please, don't forget to mark my answer as "the best" to help other people to find it.

      ​

      Regards,

      Dario. ​