Problem with charset and rewriting HTML content

Hi,

I'd go back to using a stream profile and STREAM::expression iRule. While you can't use positive lookaheads, you can modify your stream expression to match more of the source string than you need to replace and then inspect the match and customize the replacement in the STREAM_MATCHED event using STREAM::match and STREAM::replace. Here are the related wiki pages for the commands. You can check the STREAM::expression page for an example of the rewriting in STREAM_MATCH:

http://devcentral.f5.com/wiki/default.aspx/iRules/stream

http://devcentral.f5.com/wiki/default.aspx/iRules/stream__expression

This example shows how you can use STREAM::match in the STREAM_MATCHED event to check if the matched string meets some condition that can't easily be checked for using a single regex in STREAM::expression.

when HTTP_REQUEST {
    Disable the stream filter for all requests
   STREAM::disable
}
when HTTP_RESPONSE {  

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

       Match an http://*example.com string and replace it with nothing yet
      STREAM::expression {&http://.*?example\.com&&}

       Enable the stream filter for this response only  
      STREAM::enable  
   }  
}   
when STREAM_MATCHED {  

    Check if the matched string meets some condition that can't easily be checked for using a single regex in STREAM::expression
   if {[STREAM::match] starts_with "host1"}{

       Replace http:// with https:// and do the replacement
      STREAM::replace "[string map {http:// https://} [STREAM::match]]"
      log local0. "[IP::client_addr]:[TCP::local_port]: matched: [STREAM::match], replaced with: [string map {http:// https://} [STREAM::match]]"  
   }
}

Aaron

Hi hoolio

 

Thank you for the reply.... the streammatch event is a great idea thank you very much fior this great tip..... ut the issue I am facing is more generic, I have faed more than one issue due to the streaming profile limitation with regex.... one example is that I once has a string that looked something like

 

Var somevariable. = "tessting"

 

 

If I want to rewriteit with

 

/var[ ]{5,}[a-z]+[ ]{5,}=[ ]+"[a-zA-Z]"/var somevariable = "testing"

 

This will not match because the string I am trying to match is too long that the stream would not detect such length (I am probably wrong regarding this assumption but I have faced this more than once where I cannot match long strings where the same regex works with buffering technique)

 

 

Another simple example is the case insensative :) a simple and silly as it may sound but it is such a headache that I cannottell regex to match without case sensativity.

 

 

I think that the good old buffering techniqu must not be replaaced with streaming streaming is good in certain situations but in complex cases (like writing uri exnryption) we have to use bufferin what do you think hoolio?

By the way the code example I show above did not show the way I wrote it... I actually addded a lot of spaces between the words

Can you put your post in [ code ] [/ code ] blocks (without the spaces) to preserve the characters?

 

 

Thanks, Aaron

Sorry about that ....... but pleae do not take my example litterly,what I was trygin to say that generally speking buffering cannot match long strings... the example I faced as far as I remember (I might be showing some mistakes) is rewriting this

var.                   Varname.     =                   "somevalue" 

And rewriting it to

var varname="somevalue"

But like I said before in complex irule like an irule that is use for identifying and encrypting uris treaming is not effecient.... so my issue is not specific to those example it is more general

Thank you hoolio

Sorry about that ....... but pleae do not take my example litterly,what I was trygin to say that generally speking buffering cannot match long strings... the example I faced as far as I remember (I might be showing some mistakes) is rewriting this

var.                   Varname.     =                   "somevalue" 

And rewriting it to

var varname="somevalue"

But like I said before in complex irule like an irule that is use for identifying and encrypting uris treaming is not effecient.... so my issue is not specific to those example it is more general

Thank you hoolio