base-golang/pkg/cidr/calc.go

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2024-07-23 10:23:43 +08:00
package cidr
import (
"bytes"
"fmt"
"math"
"net"
"sort"
)
// SuperNetting 合并网段
func SuperNetting(ns []string) (*cidr, error) {
num := len(ns)
if num < 1 || (num&(num-1)) != 0 {
return nil, fmt.Errorf("子网数量必须是2的次方")
}
mask := ""
var cidrs []*cidr
for _, n := range ns {
// 检查子网CIDR有效性
c, err := ParseCIDR(n)
if err != nil {
return nil, fmt.Errorf("网段%v格式错误", n)
}
cidrs = append(cidrs, c)
// TODO 暂只考虑相同子网掩码的网段合并
if len(mask) == 0 {
mask = c.Mask()
} else if c.Mask() != mask {
return nil, fmt.Errorf("子网掩码不一致")
}
}
AscSortCIDRs(cidrs)
// 检查网段是否连续
var network net.IP
for _, c := range cidrs {
if len(network) > 0 {
if !network.Equal(c.ipNet.IP) {
return nil, fmt.Errorf("必须是连续的网段")
}
}
network = net.ParseIP(c.Broadcast())
IncrIP(network)
}
// 子网掩码左移,得到共同的父网段
c := cidrs[0]
ones, bits := c.MaskSize()
ones = ones - int(math.Log2(float64(num)))
c.ipNet.Mask = net.CIDRMask(ones, bits)
c.ipNet.IP.Mask(c.ipNet.Mask)
return c, nil
}
// IncrIP IP地址自增
func IncrIP(ip net.IP) {
for i := len(ip) - 1; i >= 0; i-- {
ip[i]++
if ip[i] > 0 {
break
}
}
}
// DecrIP IP地址自减
func DecrIP(ip net.IP) {
length := len(ip)
for i := length - 1; i >= 0; i-- {
ip[length-1]--
if ip[length-1] < 0xFF {
break
}
for j := 1; j < length; j++ {
ip[length-j-1]--
if ip[length-j-1] < 0xFF {
return
}
}
}
}
// Compare 比较IP大小 a等于b返回0; a大于b返回+1; a小于b返回-1
func Compare(a, b net.IP) int {
return bytes.Compare(a, b)
}
// AscSortCIDRs 升序
func AscSortCIDRs(cs []*cidr) {
sort.Slice(cs, func(i, j int) bool {
if n := bytes.Compare(cs[i].ipNet.IP, cs[j].ipNet.IP); n != 0 {
return n < 0
}
if n := bytes.Compare(cs[i].ipNet.Mask, cs[j].ipNet.Mask); n != 0 {
return n < 0
}
return false
})
}
// DescSortCIDRs 降序
func DescSortCIDRs(cs []*cidr) {
sort.Slice(cs, func(i, j int) bool {
if n := bytes.Compare(cs[i].ipNet.IP, cs[j].ipNet.IP); n != 0 {
return n >= 0
}
if n := bytes.Compare(cs[i].ipNet.Mask, cs[j].ipNet.Mask); n != 0 {
return n >= 0
}
return false
})
}