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doc_hack_12696's avatar
doc_hack_12696
Icon for Nimbostratus rankNimbostratus
Oct 21, 2010

URI substitution

I am trying to change the URI such that CI in the URI is replaced by the value obtained in the FILTER http header. I need to make it in such a way that the user still sees /csn/CI/value1/generic.html while the re-write now maps to /csn/{value in FILTER header}/value1/generic.html

 

 

This is what I wrote

 

 

 

when HTTP_REQUEST {

 

if { [HTTP::uri] starts_with "/csn/CI/" } {

 

set NCI [HTTP::header "FILTER"]

 

log local0. "$NCI"

 

HTTP::uri [string map {/csn/CI/ /csn/"$NCI"/} [HTTP::uri]]

 

log local0. [string map {/csn/CI/ /csn/"$NCI"/} [HTTP::path]]

 

HTTP::path [string map -nocase {/csn/CI/ /csn/"$NCI"/} [HTTP::path]]

 

 

}

 

}

 

 

Problem is that the url https://xyz.com/csn/CI/value1/generic.html is being re-written to https://xyz.com/csn/"$NCI"/value1/generic.html

 

I want it to be https://xyz.com/csn/IBMCORP/value1/generic.html

 

So the value for $NCI is not being substituted. However for log.local0. "NCI" actually prints out the right value = IBMCORP
application delivery
dev
devops
iRules

9 Replies

  • hoolio's avatar
    hoolio
    Icon for Cirrostratus rankCirrostratus
    Oct 21, 2010
    Hi,

     

     

    The curly braces prevent variable expansion. So the string map is probably doing a literal replacement of "$NCI". If you replace the curly braces with double quotes it should work:

     

     

    HTTP::path [string map -nocase "/csn/CI/ /csn/$NCI/" [HTTP::path]]

     

     

    Aaron
  • greeblesnort's avatar
    greeblesnort
    Icon for Nimbostratus rankNimbostratus
    Jan 20, 2012
    sorry to revive an old thread, but this is very similar to my current issue. I'm trying to rewrite an incoming request thusly: 

    when HTTP_REQUEST {set OLDPATH [HTTP::path]log local0.info "got request for $OLDPATH"if {[HTTP::path] starts_with "/dealers"} {HTTP::path [string map -nocase "/dealers/ /used_car_classifieds/dealer/" [HTTP::path]]set NEWPATH [HTTP::path]log local0. "$OLDPATH should've been rewritten to $NEWPATH"}}

    Log output is:

    Jan 20 15:17:38 local/tmm info tmm[5350]: Rule dvlp_dealer_rewrite : /dealers/IL/Chicago/VOLVO should've been rewritten to /dealers/IL/Chicago/VOLVO

    so the rule is firing, but I'm either not doing the string map correctly, or the [HTTP::path] isn't getting updated?

  • hoolio's avatar
    hoolio
    Icon for Cirrostratus rankCirrostratus
    Jan 20, 2012
    The results for these HTTP:: commands are cached in the same event and event priority:

    HTTP::password

    HTTP::username

    HTTP::host

    HTTP::path

    HTTP::query

    HTTP::request_num

    HTTP::status

    HTTP::uri

    HTTP::is_keepalive

    HTTP::is_redirect

    HTTP::request

    In v11, this caching was fixed so that if one of the request components was updated the cached value would be updated too. I assume you're testing on v10 so you'll still see the cached value. If you want to verify the rewrite is being done as expected, you can use a later HTTP_REQUEST priority: 

    when HTTP_REQUEST priority 501 {

    This event runs after the HTTP_REQUEST event with a default priority of 500
   log local0. "Updated \[HTTP::path\]: [HTTP::path]"
}

    Aaron
  • greeblesnort's avatar
    greeblesnort
    Icon for Nimbostratus rankNimbostratus
    Jan 20, 2012
    Running 10.2.3 build 123.0 HF1, so yes, we're still on 10.

     

     

    Regarding priority, I turned up logging trying to troubleshoot this and see this in the logs:

     

    Jan 20 15:12:22 local/tmm debug tmm[5350]: 01220003:7: Virtual dvlp_cfx_vs - Updated rule dvlp_dealer_rewrite when priority 32768000

     

     

     

     

    Is this a different priority or do we have a setting out of wack somewhere? I know I've read that, by default, iRules are priority 500(?), and I don't recall changing it, but this setup is only about 2 weeks old, so we're still in the "getting comfortable with it" phase.

     

     

     

     

     

  • greeblesnort's avatar
    greeblesnort
    Icon for Nimbostratus rankNimbostratus
    Jan 20, 2012
    Running 10.2.3 build 123.0 HF1, so yes, we're still on 10.

     

     

    Regarding priority, I turned up logging trying to troubleshoot this and see this in the logs:

     

    Jan 20 15:12:22 local/tmm debug tmm[5350]: 01220003:7: Virtual dvlp_cfx_vs - Updated rule dvlp_dealer_rewrite when priority 32768000

     

     

     

     

    Is this a different priority or do we have a setting out of wack somewhere? I know I've read that, by default, iRules are priority 500(?), and I don't recall changing it, but this setup is only about 2 weeks old, so we're still in the "getting comfortable with it" phase.

     

     

     

     

     

  • greeblesnort's avatar
    greeblesnort
    Icon for Nimbostratus rankNimbostratus
    Jan 20, 2012
    Running 10.2.3 build 123.0 HF1, so yes, we're still on 10.

    Regarding priority, I turned up logging trying to troubleshoot this and see this in the logs:

    Jan 20 15:12:22 local/tmm debug tmm[5350]: 01220003:7: Virtual dvlp_cfx_vs - Updated rule dvlp_dealer_rewrite when priority 32768000

    Is this a different priority or do we have a setting out of wack somewhere? I know I've read that, by default, iRules are priority 500, and I don't recall changing it, but this setup is only about 2 weeks old, so we're still in the "getting comfortable with it" phase.

  • hoolio's avatar
    hoolio
    Icon for Cirrostratus rankCirrostratus
    Jan 20, 2012
    If you don't specify the priority for an iRule or iRule event it defaults to 500. For your HTTP::path rewrite to work, you don't need to set a custom priority. The rewrite should be working fine as it is. To see the change logged you could add the debug event with a higher priority.

     

     

    Here's the priority wiki page for some background:

     

    http://devcentral.f5.com/wiki/iRules.priority.ashx

     

     

    Aaron