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CSA's avatar
CSA
Icon for Nimbostratus rankNimbostratus
Mar 23, 2010

Adding www. before HTTP::host / regexp matching

Hi,

 

 

We have today many websites like www.AA.domain.com where AA is a ccTLD (a country code). We want to have the websites working when users type AA.domain.com.

 

 

In the DNS, AA.domain.com is a CNAME to www.AA.domain.com.

 

 

I want to make the BigIP rewrite AA.domain.com to www.AA.domain.com

 

 

I did this but it doesn't work:

 

 

when HTTP_REQUEST {

 

if { [ string tolower [HTTP::host] ] matches_regex "(?:^\w\w\.domain\.com$)" } {

 

HTTP::redirect "http://www.[HTTP::host]/[HTTP::uri]"

 

}

 

}

 

 

Any idea why it doesn't work ? I don't find many doc about regexp in irules.

 

 

Many thanks,
application delivery
dev
devops
iRules

11 Replies

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  • CSA's avatar
    CSA
    Icon for Nimbostratus rankNimbostratus
    Mar 23, 2010
    Answering myself:

     

     

    when HTTP_REQUEST {

     

    if { [ string tolower [HTTP::host] ] matches_regex {^\w\w\.domain\.com$} } {

     

    HTTP::redirect "http://www.[HTTP::host]"

     

    }

     

    }

     

     

    Any remarks are welcome if I did something wrong.

     

  • Hamish's avatar
    Hamish
    Icon for Cirrocumulus rankCirrocumulus
    Mar 23, 2010
    Hmm... Well, leaving aside the fact that you shouldn't have it as a CNAME (Because as a domain you'll have an SOA record plus maybe an MX record, and you shouldn't have any other records if you have a CNAME record). Best create it as an A record instead... Anyway...

    IIUC what you're trying to do is if the host is NOT www.domain.com then do the redirect? Sorry, I'm not sure what regex syntax you're using there, but it doesn't look right... Would 

     
  if {!(string tolower [HTTP::host]] equals "www.domain.com") } {

    work just as well? If you just to to match when the host isn't www.domain.com? Using a regex for a simple match seems a bit overkill to me.

    H
  • CSA's avatar
    CSA
    Icon for Nimbostratus rankNimbostratus
    Mar 23, 2010
    Hmm, I don't get what you mean when you say I shouldn't define CNAMEs. I don't have SOA or MX records on these entries, they are all in the domain.com zone, just standard A entries.

     

     

    Your suggestion of irule will not work. I have many other DNS entries which doesn't look like AA.domain.com.
  • hooleylist's avatar
    hooleylist
    Icon for Cirrostratus rankCirrostratus
    Mar 23, 2010
    How about a string pattern then? 

     
 when HTTP_REQUEST { 
  
    if {not [string match -nocase {[a-z][[a-z][.domain.com} [HTTP::host]] } { 
       HTTP::redirect "http://www.[HTTP::host]/[HTTP::uri]" 
    } 
 }

    Aaron
  • CSA's avatar
    CSA
    Icon for Nimbostratus rankNimbostratus
    Mar 23, 2010
    I don't want anything.domain.com to be redirected to www.anything.domain.com.

     

     

    Just 2 letters ccTLD.
  • hooleylist's avatar
    hooleylist
    Icon for Cirrostratus rankCirrostratus
    Mar 23, 2010
    Hi Christophe,

     

     

    The string match command (with the typo fixed) is equivalent to your regex:

     

     

    % regexp {(?:^\w\w\.domain\.com$)} aa.domain.com

     

    1

     

    % regexp {(?:^\w\w\.domain\.com$)} aaa.domain.com

     

    0

     

     

    % string match -nocase {[a-z][[a-z].domain.com} aa.domain.com

     

    1

     

    % string match -nocase {[a-z][[a-z].domain.com} aaa.domain.com

     

    0

     

     

    Aaron
  • CSA's avatar
    CSA
    Icon for Nimbostratus rankNimbostratus
    Mar 23, 2010
    I see...

     

    I guess using string match is faster than the regexp one ?

     

     

    Thanks for the suggestion BTW...
  • hooleylist's avatar
    hooleylist
    Icon for Cirrostratus rankCirrostratus
    Mar 23, 2010
    Yes, the string match command is more efficient than the regexp by a factor of 10 in a simple tclsh test:

     

     

    % time {regexp {(?:^\w\w\.domain\.com$)} aa.domain.com} 1000

     

    20 microseconds per iteration

     

     

    % time {string match -nocase {[a-z][[a-z].domain.com} aa.domain.com} 1000

     

    2 microseconds per iteration

     

     

    Aaron
  • Andrea_Arquint's avatar
    Andrea_Arquint
    Icon for Nimbostratus rankNimbostratus
    Oct 21, 2010
    Hi all

     

     

    How do you run this command?

     

     

     

    % regexp {(?:^\w\w\.domain\.com$)} aa.domain.com

     

     

     

    Is this run on a linux bash shell???

     

    I'm using centos and I did install "regexp" but there is no binary to execute???

     

     

     

     

     

    Thanx for help

     

    bb