first commit

pkg/cidr/calc.go

@@ -0,0 +1,119 @@
+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
+	})
+}