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bilsch_10068's avatar
bilsch_10068
Icon for Nimbostratus rankNimbostratus
Oct 26, 2010

Fix to http persistence cookie logger irule

Was working with the persistence cookie logger irule, its logging the wrong value for ports.

 

 

http://devcentral.f5.com/wiki/default.aspx/iRules/Persistence_Cookie_Logger.html

 

 

Original code

 

set myPortD [string trimleft [expr 0x[substr $myPortH 2 2]][expr 0x[substr $myPortH 0 2]] 0]

 


Should be
    set myPortD [string trimleft [expr 0x[substr $myPortH 2 2][substr $myPortH 0 2]] 0]
Per the docs https://support.f5.com/kb/en-us/solutions/public/6000/900/sol6917.html , the 2-byte hex values are reversed, so should be re-ordered. However the value should be a single string, not 2 unique hex values.
( not sure if this is the best/right way to post this 😆 )

 

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  • hoolio's avatar
    hoolio
    Icon for Cirrostratus rankCirrostratus
    Nov 03, 2010
    Hi Bilsch,

    Thanks for finding, fixing and pointing this out. Your interpretation looks correct to me: 

    
when RULE_INIT {

 From http://support.f5.com/kb/en-us/solutions/public/6000/900/sol6917.html
 For example, if the port of the destination server is 8080, the BIG-IP LTM encodes the port as follows:
 8080 = 0x1F90
 Reverse byte order = 0x901F
 0x901F = 36895

set myPortE 36895
set myPortH [format %x $myPortE]
log local0. "\$myPortE: $myPortE, \$myPortH, $myPortH"

 Old, wrong way
log local0. "Old: [expr 0x[substr $myPortH 2 2]][expr 0x[substr $myPortH 0 2]]"

 Updated, correct way
log local0. "New: [expr 0x[substr $myPortH 2 2][substr $myPortH 0 2]]"

 Log output:
 : $myPortE: 36895, $myPortH, 901f
 : Old: 31144
 : New: 8080
}

    Aaron