Created
May 6, 2024 21:45
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Get last IP address of network at golang
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package main | |
import ( | |
"log" | |
"net" | |
) | |
func main() { | |
// convert string to IPNet struct | |
ip1, net1, _ := net.ParseCIDR("fd34:0135:0123::2/120") | |
ip2, net2, _ := net.ParseCIDR("10.0.1.2/20") | |
last1 := lastIP(net1) | |
log.Printf("ip1: %s, net1: %d, last1: %s", ip1, net1.Mask, last1) | |
last2 := lastIP(net2) | |
log.Printf("ip2: %s, net2: %d, last2: %s", ip2, net2.Mask, last2) | |
} | |
func lastIP(n *net.IPNet) net.IP { | |
lastIp, lastMask, _ := net.ParseCIDR("fd::/128") | |
size := 16 | |
if n.IP.To4() != nil { | |
lastIp, lastMask, _ = net.ParseCIDR("10.0.0.1/32") | |
log.Println(len(lastIp)) | |
size = 4 | |
} | |
for i := 0; i < size; i++ { | |
lastIp[i] = (n.IP[i] & n.Mask[i]) | (n.Mask[i] ^ lastMask.Mask[i]) | |
} | |
return lastIp[:size] | |
} |
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