gawk¶

• gawk
• Sorting IPv4 addresses
  • Function cmp_ip_addr
  • Usage example

Sorting IPv4 addresses¶

Function cmp_ip_addr¶

# cmp_ip_addr
# For asort() to call
# Compares IP addresses in values v1 and v1
function cmp_ip_addr (i1, v1, i2, v2, \
    v1_octets, v2_octets)
{
    #print "i1: " i1 ", v1: " v1 ", i2: " i2 ", v2: " v2
    split(v1, v1_octets, ".") 
    split(v2, v2_octets, ".") 

    #print "v1_octets[4]: " v1_octets[4] ", v2_octets[4]: " v2_octets[4]
    if (v1_octets[1]+0 < v2_octets[1]+0)
        return -1
    else if (v1_octets[1]+0 == v2_octets[1]+0) {
        if (v1_octets[2]+0 < v2_octets[2]+0)    
            return -1
        else if (v1_octets[2]+0 == v2_octets[2]+0) {
            if (v1_octets[3]+0 < v2_octets[3]+0)
                return -1
            else if (v1_octets[3]+0 == v2_octets[3]+0) {
                if (v1_octets[4]+0 < v2_octets[4]+0)
                    return -1
                else if (v1_octets[4]+0 == v2_octets[4]+0) {
                    return 0
                }   
                else
                    return 1
            }   
            else
                return 1
        }   
        else
            return 1
    }   
    else
        return 1
}

Usage example¶

Addresses is an array with (FQDNs as indices and) IP addresses as values. Array networks is derived containing in ascending order all the unique /24 networks corresponding to the IP addresses from array Addresses.

    # Create array of indices to Addresses in address order
    # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    addresses_n = asort(Addresses, addresses_sorted, "cmp_ip_addr"))

    # Create sorted list of /24 networks
    # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    for (i = 1; i <= addresses_n; i++)
    {
        address = addresses_sorted[i]
        network = gensub(/\.[^.]+$/, "", 1, address)
        networks[network] = "" 
    }