Forum Discussion

soymanue's avatar
soymanue
Icon for Nimbostratus rankNimbostratus
Oct 12, 2012

Hostname split

Hello

 

I need to split a hostname into three parts ( ..).

 

This can be done al least on two ways:

 

1) scan [HTTP::host] %\[^.\].%\[^.\].%s prefix host suffix

 

 

2) set prefix [getfield [HTTP::host] "." 1]

 

set host [getfield [HTTP::host] "." 2]

 

set suffix [getfield [HTTP::host] "." 3]

 

 

Both work, but the problem comes when there is no prefix ( f5.com instead of www.f5.com). In that case scan fails and the second method leaves suffix empy, assign .com to host and f5 to prefix

 

I've done this to solve this:

 

set longitud [ string length $suffix ]

 

if { $longitud < 1 } {

 

set host [string tolower $prefix ]

 

}

 

It works, but it doesn't look quite ellegant nor efficient.

 

 

Is there a better way to solve that particular case?

 

Thank you.

 

application delivery
dev
devops
iRules

9 Replies

Sort By
  • nitass's avatar
    nitass
    Icon for Employee rankEmployee
    Oct 12, 2012
    this is mine but i think it is not efficient anyway. 🙂 

    [root@ve10:Active] config  b rule myrule list
rule myrule {
   when RULE_INIT {
   set hostname "f5.com"
   set last_dot [string last "." $hostname]
   set second_dot [string last "." $hostname [expr {$last_dot -1}]]
   set suffix [string range $hostname [expr {$last_dot + 1}] end]
   set host [string range $hostname [expr {$second_dot + 1}] [expr {$last_dot - 1}]]
   set prefix [string range $hostname 0 [expr {$second_dot - 1}]]
   log local0. "hostname=$hostname | prefix=$prefix | host=$host | suffix=$suffix"

   set hostname "www.f5.com"
   set last_dot [string last "." $hostname]
   set second_dot [string last "." $hostname [expr {$last_dot -1}]]
   set suffix [string range $hostname [expr {$last_dot + 1}] end]
   set host [string range $hostname [expr {$second_dot + 1}] [expr {$last_dot - 1}]]
   set prefix [string range $hostname 0 [expr {$second_dot - 1}]]
   log local0. "hostname=$hostname | prefix=$prefix | host=$host | suffix=$suffix"

   set hostname "xxx.yyy.f5.com"
   set last_dot [string last "." $hostname]
   set second_dot [string last "." $hostname [expr {$last_dot -1}]]
   set suffix [string range $hostname [expr {$last_dot + 1}] end]
   set host [string range $hostname [expr {$second_dot + 1}] [expr {$last_dot - 1}]]
   set prefix [string range $hostname 0 [expr {$second_dot - 1}]]
   log local0. "hostname=$hostname | prefix=$prefix | host=$host | suffix=$suffix"
}
}

[root@ve10:Active] config  tail -f /var/log/ltm
Oct 12 19:25:48 local/ve10 err mcpd[3815]: 01020066:3: The requested rule (myrule) already exists in partition Common.
Oct 12 19:25:48 local/tmm info tmm[7926]: Rule myrule : hostname=f5.com | prefix= | host=f5 | suffix=com
Oct 12 19:25:48 local/tmm info tmm[7926]: Rule myrule : hostname=www.f5.com | prefix=www | host=f5 | suffix=com
Oct 12 19:25:48 local/tmm info tmm[7926]: Rule myrule : hostname=xxx.yyy.f5.com | prefix=xxx.yyy | host=f5 | suffix=com
  • What_Lies_Bene1's avatar
    What_Lies_Bene1
    Icon for Cirrostratus rankCirrostratus
    Oct 12, 2012

    I wouldn't know how to code it but assuming you know that the domain name or names will always end .com or whatever, why not just compare $host against .com and if it's a match, shuffle your fields: set suffix = $host, set host = $prefix, set prefix = "blank"?

     

  • soymanue's avatar
    soymanue
    Icon for Nimbostratus rankNimbostratus
    Oct 12, 2012

    We have several suffixes: .com, .org, .es, .biz, .eu, .int

     

     

  • soymanue's avatar
    soymanue
    Icon for Nimbostratus rankNimbostratus
    Oct 12, 2012
    I don't how how does it work

     

    Where can I find and example?

     

    Thanks
  • Kevin_Stewart's avatar
    Kevin_Stewart
    Icon for Employee rankEmployee
    Oct 12, 2012
    I'd probably turn it into a list: 

    
set myhost [split [HTTP::host] "."]

    Then you could use the full force of list commands for processing.

    - llength to determine the size of the hostname

    - the last index is the root: [expr [llength $mylist] - 1]
  • What_Lies_Bene1's avatar
    What_Lies_Bene1
    Icon for Cirrostratus rankCirrostratus
    Oct 12, 2012
    Kevin's probably onto something there but if you did take the data group route, create and populate the data group and use code something like this;

     

     

    
if { [class match [string tolower $host] contains suffix_data_group ] } {
            'do something here'
        }
  • nitass's avatar
    nitass
    Icon for Employee rankEmployee
    Oct 12, 2012
    i like Kevin's idea. 

    [root@ve10:Active] config  b rule myrule list
rule myrule {
   when RULE_INIT {
   set hostname "f5.com"
   set lhostname [split $hostname "."]
   set suffix [lindex $lhostname [expr {[llength $lhostname] - 1}]]
   set host [lindex $lhostname [expr {[llength $lhostname] - 2}]]
   set prefix [lindex $lhostname [expr {[llength $lhostname] - 3}]]
   for {set i [expr {[llength $lhostname] - 4}]} {$i >= 0} {incr i -1} {
      set prefix "[lindex $lhostname $i].$prefix"
   }
   log local0. "hostname=$hostname | prefix=$prefix | host=$host | suffix=$suffix"

   set hostname "www.f5.com"
   set lhostname [split $hostname "."]
   set suffix [lindex $lhostname [expr {[llength $lhostname] - 1}]]
   set host [lindex $lhostname [expr {[llength $lhostname] - 2}]]
   set prefix [lindex $lhostname [expr {[llength $lhostname] - 3}]]
   for {set i [expr {[llength $lhostname] - 4}]} {$i >= 0} {incr i -1} {
      set prefix "[lindex $lhostname $i].$prefix"
   }
   log local0. "hostname=$hostname | prefix=$prefix | host=$host | suffix=$suffix"

   set hostname "xxx.yyy.f5.com"
   set lhostname [split $hostname "."]
   set suffix [lindex $lhostname [expr {[llength $lhostname] - 1}]]
   set host [lindex $lhostname [expr {[llength $lhostname] - 2}]]
   set prefix [lindex $lhostname [expr {[llength $lhostname] - 3}]]
   for {set i [expr {[llength $lhostname] - 4}]} {$i >= 0} {incr i -1} {
      set prefix "[lindex $lhostname $i].$prefix"
   }
   log local0. "hostname=$hostname | prefix=$prefix | host=$host | suffix=$suffix"
}
}

[root@ve10:Active] config  tail -f /var/log/ltm
Oct 12 19:58:52 local/ve10 err mcpd[3815]: 01020066:3: The requested rule (myrule) already exists in partition Common.
Oct 12 19:58:52 local/tmm info tmm[7926]: Rule myrule : hostname=f5.com | prefix= | host=f5 | suffix=com
Oct 12 19:58:52 local/tmm info tmm[7926]: Rule myrule : hostname=www.f5.com | prefix=www | host=f5 | suffix=com
Oct 12 19:58:52 local/tmm info tmm[7926]: Rule myrule : hostname=xxx.yyy.f5.com | prefix=xxx.yyy | host=f5 | suffix=com