first commit

pkg/cidr/ip.go

@@ -0,0 +1,194 @@
+package cidr
+
+import (
+	"encoding/hex"
+	"fmt"
+	"math"
+	"math/big"
+	"net"
+)
+
+// 裂解子网的方式
+const (
+	MethodSubnetNum = 0 // 基于子网数量
+	MethodHostNum   = 1 // 基于主机数量
+)
+
+var _ CIDR = (*cidr)(nil)
+
+type CIDR interface {
+	CIDR() string
+	IP() string
+	Network() string
+	Broadcast() string
+	Mask() string
+	MaskSize() (int, int)
+	IPRange() (string, string)
+	IPCount() *big.Int
+
+	IsIPv4() bool
+	IsIPv6() bool
+
+	Equal(string) bool
+	Contains(string) bool
+	ForEachIP(func(string) error) error
+	ForEachIPBeginWith(string, func(string) error) error
+	SubNetting(method, num int) ([]*cidr, error)
+}
+
+type cidr struct {
+	ip    net.IP
+	ipNet *net.IPNet
+}
+
+// ParseCIDR 解析CIDR网段
+func ParseCIDR(s string) (*cidr, error) {
+	i, n, err := net.ParseCIDR(s)
+	if err != nil {
+		return nil, err
+	}
+	return &cidr{ip: i, ipNet: n}, nil
+}
+
+// Equal 判断网段是否相等
+func (c *cidr) Equal(ns string) bool {
+	c2, err := ParseCIDR(ns)
+	if err != nil {
+		return false
+	}
+	return c.ipNet.IP.Equal(c2.ipNet.IP) /* && c.ipNet.IP.Equal(c2.ip) */
+}
+
+// IsIPv4 判断是否IPv4
+func (c *cidr) IsIPv4() bool {
+	_, bits := c.ipNet.Mask.Size()
+	return bits/8 == net.IPv4len
+}
+
+// IsIPv6 判断是否IPv6
+func (c *cidr) IsIPv6() bool {
+	_, bits := c.ipNet.Mask.Size()
+	return bits/8 == net.IPv6len
+}
+
+// Contains 判断IP是否包含在网段中
+func (c *cidr) Contains(ip string) bool {
+	return c.ipNet.Contains(net.ParseIP(ip))
+}
+
+// CIDR 根据子网掩码长度校准后的CIDR
+func (c *cidr) CIDR() string {
+	return c.ipNet.String()
+}
+
+// IP CIDR字符串中的IP部分
+func (c *cidr) IP() string {
+	return c.ip.String()
+}
+
+// Network 网络号
+func (c *cidr) Network() string {
+	return c.ipNet.IP.String()
+}
+
+// MaskSize 子网掩码位数
+func (c *cidr) MaskSize() (ones, bits int) {
+	ones, bits = c.ipNet.Mask.Size()
+	return
+}
+
+// Mask 子网掩码
+func (c *cidr) Mask() string {
+	mask, _ := hex.DecodeString(c.ipNet.Mask.String())
+	return net.IP([]byte(mask)).String()
+}
+
+// Broadcast 广播地址(网段最后一个IP)
+func (c *cidr) Broadcast() string {
+	mask := c.ipNet.Mask
+	bcst := make(net.IP, len(c.ipNet.IP))
+	copy(bcst, c.ipNet.IP)
+	for i := 0; i < len(mask); i++ {
+		ipIdx := len(bcst) - i - 1
+		bcst[ipIdx] = c.ipNet.IP[ipIdx] | ^mask[len(mask)-i-1]
+	}
+	return bcst.String()
+}
+
+// IPRange 起始IP、结束IP
+func (c *cidr) IPRange() (start, end string) {
+	return c.Network(), c.Broadcast()
+}
+
+// IPCount IP数量
+func (c *cidr) IPCount() *big.Int {
+	ones, bits := c.ipNet.Mask.Size()
+	return big.NewInt(0).Lsh(big.NewInt(1), uint(bits-ones))
+}
+
+// ForEachIP 遍历网段下所有IP
+func (c *cidr) ForEachIP(iterator func(ip string) error) error {
+	next := make(net.IP, len(c.ipNet.IP))
+	copy(next, c.ipNet.IP)
+	for c.ipNet.Contains(next) {
+		if err := iterator(next.String()); err != nil {
+			return err
+		}
+		IncrIP(next)
+	}
+	return nil
+}
+
+// ForEachIPBeginWith 从指定IP开始遍历网段下后续的IP
+func (c *cidr) ForEachIPBeginWith(beginIP string, iterator func(ip string) error) error {
+	next := net.ParseIP(beginIP)
+	for c.ipNet.Contains(next) {
+		if err := iterator(next.String()); err != nil {
+			return err
+		}
+		IncrIP(next)
+	}
+	return nil
+}
+
+// SubNetting 裂解网段
+func (c *cidr) SubNetting(method, num int) ([]*cidr, error) {
+	if num < 1 || (num&(num-1)) != 0 {
+		return nil, fmt.Errorf("裂解数量必须是2的次方")
+	}
+
+	newOnes := int(math.Log2(float64(num)))
+	ones, bits := c.MaskSize()
+	switch method {
+	default:
+		return nil, fmt.Errorf("不支持的裂解方式")
+	case MethodSubnetNum:
+		newOnes = ones + newOnes
+		// 如果子网的掩码长度大于父网段的长度，则无法裂解
+		if newOnes > bits {
+			return nil, nil
+		}
+	case MethodHostNum:
+		newOnes = bits - newOnes
+		// 如果子网的掩码长度小于等于父网段的掩码长度，则无法裂解
+		if newOnes <= ones {
+			return nil, nil
+		}
+		// 主机数量转换为子网数量
+		num = int(math.Pow(float64(2), float64(newOnes-ones)))
+	}
+
+	var cidrs []*cidr
+	network := make(net.IP, len(c.ipNet.IP))
+	copy(network, c.ipNet.IP)
+	for i := 0; i < num; i++ {
+		cidr, _ := ParseCIDR(fmt.Sprintf("%v/%v", network.String(), newOnes))
+		cidrs = append(cidrs, cidr)
+
+		// 广播地址的下一个IP即为下一段的网络号
+		network = net.ParseIP(cidr.Broadcast())
+		IncrIP(network)
+	}
+
+	return cidrs, nil
+}