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Joe_Erchul_4263's avatar
Joe_Erchul_4263
Icon for Nimbostratus rankNimbostratus
Jul 17, 2013

Stripping chromeframe from User-Agent

Gang,

 

The chromeframe information in Header Value User-Agent is messing up one of our new applications. I'd like to strip just that information from the User-Agent. I've got an iRule written as follows:

 

when HTTP_REQUEST {

 

set useragent [string tolower [HTTP::header value User-Agent]]

 

if {$useragent contains "chromeframe"} {

 

HTTP::header value User-Agent [string map -nocase {"chromeframe/26.0.1410.64;" ""} $useragent]

 

}

 

}

 

This particular rule is throwing an error in the log, even though my F5 is storing the iRule correctly:

 

Jul 17 12:04:28 slot1/tmm1 err tmm1[6850]: 01220001:3: TCL error: /Common/chromeframe_strip - Illegal argument. Please check required arguments and their respective types (line 1) invoked from within "HTTP::header value User-Agent [string map -nocase {"chromeframe/26.0.1410.64;" ""} $useragent]"

 

 

Any advice is appreciated.

 

 

Thanks.

 

 

Joe

 

 

application delivery
dev
devops
iRules

3 Replies

  • Kevin_Stewart's avatar
    Kevin_Stewart
    Icon for Employee rankEmployee
    Jul 17, 2013
    Two things:

     

     

    1. You want to use HTTP::header replace User-Agent to replace the UA header.

     

     

    2. Because you're using -nocase in the string map, you don't need to do the [string tolower ] first with a temporary variable.

     

  • Joe_Erchul_4263's avatar
    Joe_Erchul_4263
    Icon for Nimbostratus rankNimbostratus
    Jul 17, 2013

    Kevin,

     

     

    That seemed to work mostly. Now, I'm seeing this in the logs:

     

    Pre-rule:

     

    Jul 17 13:48:17 slot1/tmm info tmm[6849]: Rule /Common/chromeframe_strip : Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.1; WOW64; Trident/4.0; chromeframe/26.0.1410.64; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET4.0E; InfoPath.3; MS-RTC LM 8; .NET CLR 1.1.4322)

     

     

    Post-rule:

     

    Jul 17 13:48:17 slot1/tmm info tmm[6849]: Rule /Common/chromeframe_strip : Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET4.0E; InfoPath.3; MS-RTC LM 8; .NET CLR 1.1.4322)

     

     

     

    Which clearly shows that the User-Agent is having the "chromeframe" information whacked. However, when I monitor via HTTPWatch, I'm still seeing the "chromeframe" information:

     

    User-Agent Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 6.1; WOW64; Trident/4.0; chromeframe/26.0.1410.64; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET4.0E; InfoPath.3; MS-RTC LM 8)

     

     

    Here's the most current version of the iRule:

     

     

    when HTTP_REQUEST {

     

    set useragent [HTTP::header value User-Agent]

     

    if {$useragent contains "chromeframe"} {

     

    log local0. $useragent

     

    HTTP::header replace User-Agent [string map -nocase {"chromeframe/26.0.1410.64;" ""} $useragent]

     

    log local0. [HTTP::header User-Agent]

     

    }

     

    }

     

     

     

     

  • Joe_Erchul_4263's avatar
    Joe_Erchul_4263
    Icon for Nimbostratus rankNimbostratus
    Jul 17, 2013

    Okay, disregard my most recent post. A capture on the server shows that the chromeframe information has been removed from User-Agent. It's just not being written back to the client on the response. Kevin, thanks for the help with this! Joe