TCL how to increment an IP

[serge123]

Hi,

I have create a tcl script to put ip in variable.

Exemple

Let say puts ": $ip "  displays 10.10.0.0

How can I split this IP to increment only the 3rd octect by 1 to make it 10.10.1.0

What is best way to do this?

[Francesco Molino]

Hi
$ip is your variable containing the IP address.
I would use the following to split the IP address.
regexp {(\d+)\.(\d+)\.(\d+)\.(\d+)} $ip match a b c d

Then to add +1 you will need to convert the value as integer. After that, you can use incr function to add +1 and join them back.

Here a reference well explained on IP address manipulation.
https://stackoverflow.com/questions/25712265/script-to-generate-n-number-of-valid-ip-addresses

[CKimmell]

proc incr_ip {IP {val 1}} {
    upvar 1 $IP ip
    set octs [split $ip "."];
    if {[llength $octs] != 4} {
        error "    Invalid IP address provided: $ip"
    }
    set pow_list  [list 3 2 1 0];
    set loop_list [list 1 2 3 4];
    #CONVERT TO IP ADDRESS TO INTEGER  
    set ip_int [expr [join [lmap oct $octs pow $pow_list l $loop_list {
        if {$oct > 255 || $oct < 0} {
            error "    Invalid IP address provided: $ip\n    Error at octet $l: $oct\n    Value outside of range (0-255)."
        }
        expr {$oct*int(pow(256,$pow))};
    }] " + "]];
    #ADD OR SUBTRACT VALUE
    incr ip_int $val;
    #CONVERT BACK TO IP ADDRESS FORMAT
    set ip [join [lmap pow $pow_list {
        set Roct [expr {$ip_int/int(pow(256,$pow))}];
        set ip_int [expr {$ip_int - $Roct * int(pow(256,$pow))}];  
        subst $Roct
    }] "."];
} 
set IPaddress 192.257.0.1
incr_ip IPaddress