Forum Discussion

MonkeyWrench_10's avatar
MonkeyWrench_10
Icon for Nimbostratus rankNimbostratus
Aug 31, 2011

How to inspect POST data on HTTP_REQUEST

Hi,

 

 

I'm trying to route users based on the payload of a POST request, and failing :)

 

 

 

Here's a simplified version of my iRule:

 

 

 

when HTTP_REQUEST {

 

HTTP::collect 100

 

if { [HTTP::method] equals "POST" } {

 

HTTP::collect [HTTP::header "Content-Length"]

 

log local0. "CONTENT LENGTH 1 = [HTTP::header "Content-Length"]"

 

log local0. "CONTENT LENGTH 2 = [HTTP::payload length]"

 

log local0. "CONTENT = [HTTP::payload 100]"

 

log local0. "URI: --[HTTP::uri]--"

 

if { [HTTP::payload 100] starts_with "SCREEN_ID=" } {

 

log local0. "PAYLOAD IS NOT EMPTY: [HTTP::payload 100]"

 

}

 

}

 

pool QAMEFT02E1NaviNetHTTPBrowser

 

}

 

 

 

 

Log output shows the payload is always empty, even though it's not. The log statement appear to conflict - [HTTP::header "Content-Length"] returns the correct value, [HTTP::payload length] always returns 0, and [HTTP::payload 100] always returns empty string.

 

 

 

Am I doing this wrong? What's the correct way to grab POST request payload? Thanks in advance,

 

 

 

-Daire

 

application delivery
dev
devops
iRules
  • Colin_Walker_12's avatar
    Colin_Walker_12
    Historic F5 Account
    Aug 31, 2011
    Is there a reason your HTTP::collect line is commented out? Have you tried uncommenting it? ;)

     

     

    Colin
  • hooleylist's avatar
    hooleylist
    Icon for Cirrostratus rankCirrostratus
    Aug 31, 2011
    HTTP::payload should normally return any payload bytes received in the first packet containing the HTTP headers.

    Regardless to guarantee collection of the full HTTP payload, you need to call HTTP::collect. Make sure to limit collect to less than 4Mb to avoid a TMM crash: 

     From http://devcentral.f5.com/wiki/iRules.http__collect.ashx
when HTTP_REQUEST {

  if {[HTTP::method] eq "POST"}{
     Trigger collection for up to 1MB of data
    if {[HTTP::header exists "Content-Length"] && [HTTP::header "Content-Length"] <= 1048576}{
      set content_length [HTTP::header "Content-Length"]
    } else {
        set content_length 1048576
    }
     Check if $content_length is not set to 0
    if { content_length > 0} {
      HTTP::collect $content_length
    }
  }
}
when HTTP_REQUEST_DATA {
   do stuff with the payload
  set payload [HTTP::payload]
}

    Aaron