Forum Discussion

pedinopa_170325's avatar
pedinopa_170325
Icon for Nimbostratus rankNimbostratus
Aug 07, 2018

trouble rewiting path

I need to rewrite the REQUEST path that is returned to the browser. I have an irule which reads the REQUEST path, splits it into a variable which has the path I want (I logged it to my logging server so I know it contains what I want. I am having trouble with getting the HTTP::path modified.

First use hsl::open to define where to send logs and save it as a variable HSL

when CLIENT_ACCEPTED { set hsl [HSL::open -proto UDP -pool graylog2-syslog-pool] }

when HTTP_REQUEST {

create variable to hold modified path, split on ;jsessionid

set nojsession [getfield [HTTP::path] ";jsessionid=" 1]

 Check if the path contains a jsessionid
if {[HTTP::path] contains ";jsessionid"}{
      write to log verify that the if clause and the variable are correct
     HSL::send $hsl "webmod This is the $nojsession without sessionid"
      replace the path with the variable (modified path without jsessionid)
     HTTP::path $nojsession
}

}

iRules
security
  • rob_carr's avatar
    rob_carr
    Icon for Cirrocumulus rankCirrocumulus
    Aug 08, 2018
    when CLIENT_ACCEPTED {
  set hsl [HSL::open -proto UDP -pool graylog2-syslog-pool]
}

when HTTP_REQUEST {
  create variable to hold modified path, split on ;jsessionid
  set nojsession [getfield [HTTP::path] ";jsessionid=" 1]
   Check if the path contains a jsessionid
  if {[HTTP::path] contains ";jsessionid"}{
      write to log verify that the if clause and the variable are correct
     HSL::send $hsl "webmod This is the $nojsession without sessionid"
      replace the path with the variable (modified path without jsessionid)
     HTTP::path $nojsession
  }
}
  • Andy_McGrath's avatar
    Andy_McGrath
    Icon for Cumulonimbus rankCumulonimbus
    Aug 08, 2018

    A few issues with your iRule, you are looking at the HTTP::path for a Query parameter which will never exist. Lets say the request is 

    https://some.host.com/this/is/the/path?jsessionid=thequerypart
    You would get the following returned from different iRule commands:

    • HTTP::host = 
      some.host.com
    • HTTP::path = 
      /this/is/the/path
    • HTTP::uri = 
      /this/is/the/path?jsessionid=thequerypart
    • HTTP::query = 
      jsessionid=thequerypart

    Your iRule would never find locate the 

    jsessionid
    query and is only updating the HTTP path not the query.

    The following iRule does the same but using 

    HTTP::uri
    instead of 
    HTTP::path
    :

    First use hsl::open to define where to send logs and save it as a variable HSL
when CLIENT_ACCEPTED {
    set hsl [HSL::open -proto UDP -pool graylog2-syslog-pool]
}

when HTTP_REQUEST {
     Check if the URI contains a jsessionid
    if {[HTTP::uri] contains ";jsessionid="}{
         Create variable to hold modified URI, split on ;jsessionid
        set nojsession [getfield [HTTP::uri] ";jsessionid=" 1]
        
         Write to log verify that the if clause and the variable are correct
        HSL::send $hsl "webmod This is the $nojsession without sessionid"
        
         Replace the URI with the variable (modified URI without jsessionid)
        HTTP::uri $nojsession
    }
}

    Quick note about this iRule if the request contains any query parameters after the 

    jsessionid
    then they will be lost as the 
    getfield
    command only takes the first part of the URI.

    e.g. If the URI requested is 

    /this/is/the/path?page=test;jsessionid=thequerypart;user=bob
    the updated request would be 
    /this/is/the/path?page=test
    and the query parameter 
    user=bob
    would be lost.