hash persistence based on source ip network

I've come up with something that looks like it might work:

 

 

rule persnickety_application {

 

when HTTP_REQUEST {

 

set first [ getfield [IP::remote_addr] "." 1]

 

set second [ getfield [IP::remote_addr] "." 2 ]

 

set third [ getfield [IP::remote_addr] "." 3 ]

 

pool temperamental_servers

 

set client_net [ crc32 [ concat $first $second $third ] ]

 

persist hash $client_net

 

}

 

}

 

 

but is there a way to consolidate the three getfield operations into a single stroke?

 

 

Thoughts on how well this might work?

 

 

Thanks,

 

Peter