mirror of
https://github.com/oneclickvirt/basics.git
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283 lines
9.0 KiB
Go
283 lines
9.0 KiB
Go
//go:build linux
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// +build linux
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package ipv6
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import (
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"context"
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"fmt"
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"net"
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"os"
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"os/exec"
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"regexp"
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"sort"
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"strings"
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"syscall"
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"time"
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)
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// Router Advertisement前缀选项类型
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const (
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ICMPv6RouterAdvertisement = 134
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ICMPv6RouterSolicitation = 133
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ICMPv6OptionPrefix = 3
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)
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// 从RA报文中提取前缀长度信息
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func extractPrefixFromRAOption(data []byte) []string {
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var prefixLengths []string
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// 跳过ICMPv6头部(4字节)和Router Advertisement基本信息(12字节)
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optionStart := 16
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// 遍历所有选项
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for optionStart < len(data) {
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// 确保有足够的数据可读
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if optionStart+2 > len(data) {
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break
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}
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optionType := data[optionStart]
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optionLen := data[optionStart+1] * 8 // 长度以8字节为单位
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// 确保选项长度有效
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if optionLen == 0 || optionStart+int(optionLen) > len(data) {
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break
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}
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// 解析前缀信息选项
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if optionType == ICMPv6OptionPrefix && optionLen >= 32 {
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// 前缀长度在选项开始后2字节处
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prefixLen := data[optionStart+2]
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// 前缀值从选项开始后16字节处
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prefixStart := optionStart + 16
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if prefixStart+16 <= len(data) {
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var prefix [16]byte
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copy(prefix[:], data[prefixStart:prefixStart+16])
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// 排除非全局单播地址
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if !isNonGlobalPrefix(prefix) {
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prefixLengths = append(prefixLengths, fmt.Sprintf("%d", prefixLen))
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}
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}
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}
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optionStart += int(optionLen)
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}
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return prefixLengths
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}
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// 发送Router Solicitation消息
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func sendRouterSolicitation(fd int, interfaceName string) error {
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// 获取接口信息
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intf, err := net.InterfaceByName(interfaceName)
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if err != nil {
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return fmt.Errorf("获取接口信息失败: %v", err)
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}
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// 构造ICMPv6 Router Solicitation消息
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// ICMPv6头部(4字节): 类型(1字节) + 代码(1字节) + 校验和(2字节)
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msg := make([]byte, 8)
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msg[0] = ICMPv6RouterSolicitation // 类型:Router Solicitation
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msg[1] = 0 // 代码:0
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// msg[2]和msg[3]是校验和字段，暂时为0，稍后计算
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// 可选：添加Source Link-Layer Address选项（MAC地址）
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// 这对一些路由器来说可能是必要的
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if len(intf.HardwareAddr) == 6 { // 确保MAC地址有效
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// 添加源链路层地址选项
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// 选项类型(1) + 长度(1) + MAC地址(6)
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msg = append(msg, 1) // 选项类型:1 (Source Link-Layer Address)
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msg = append(msg, 1) // 长度:1 (以8字节为单位，这里是8字节)
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msg = append(msg, intf.HardwareAddr...) // MAC地址
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msg = append(msg, 0, 0) // 填充到8字节对齐
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}
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// 设置ICMPv6的目标地址为All Routers组播地址
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var allRoutersAddr [16]byte
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copy(allRoutersAddr[:], net.ParseIP("ff02::2").To16())
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// 构造sockaddr_in6结构
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var addr syscall.SockaddrInet6
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addr.ZoneId = uint32(intf.Index)
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copy(addr.Addr[:], allRoutersAddr[:])
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// 发送数据包
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if err := syscall.Sendto(fd, msg, 0, &addr); err != nil {
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return fmt.Errorf("发送Router Solicitation失败: %v", err)
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}
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return nil
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}
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// 方法1：尝试原生实现从Router Advertisement获取前缀长度
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func getPrefixFromRA(interfaceName string) (string, error) {
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// 尝试先用radvdump，如果存在的话
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radvdumpPath, err := exec.LookPath("radvdump")
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if err == nil && radvdumpPath != "" {
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cmd := exec.Command("radvdump", "-i", interfaceName)
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output, err := cmd.Output()
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if err == nil {
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re := regexp.MustCompile(`(?i)prefix\s+([a-fA-F0-9:]+)/(\d+)`)
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matches := re.FindAllStringSubmatch(string(output), -1)
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for _, match := range matches {
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prefix := match[1]
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prefixLen := match[2]
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// 排除非公网地址前缀
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if !strings.HasPrefix(prefix, "fe80") &&
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!strings.HasPrefix(prefix, "::1") &&
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!strings.HasPrefix(prefix, "fc") &&
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!strings.HasPrefix(prefix, "fd") &&
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!strings.HasPrefix(prefix, "ff") {
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return prefixLen, nil
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}
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}
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}
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}
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// 如果radvdump不可用或未找到有效前缀，使用原生实现
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intf, err := net.InterfaceByName(interfaceName)
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if err != nil {
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return "", fmt.Errorf("获取网络接口失败: %v", err)
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}
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// 创建原始套接字接收ICMPv6消息
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fd, err := syscall.Socket(syscall.AF_INET6, syscall.SOCK_RAW, syscall.IPPROTO_ICMPV6)
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if err != nil {
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return "", fmt.Errorf("创建原始套接字失败: %v", err)
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}
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defer syscall.Close(fd)
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// 绑定到指定接口
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if err := syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_BINDTODEVICE, intf.Index); err != nil {
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return "", fmt.Errorf("绑定套接字到接口失败: %v", err)
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}
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// 设置过滤器，只接收Router Advertisement消息
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if err := syscall.SetsockoptInt(fd, syscall.IPPROTO_IPV6, syscall.IPV6_RECVPKTINFO, 1); err != nil {
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return "", fmt.Errorf("设置套接字选项失败: %v", err)
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}
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// 设置接收超时
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tv := syscall.Timeval{
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Sec: 5, // 5秒超时
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Usec: 0,
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}
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if err := syscall.SetsockoptTimeval(fd, syscall.SOL_SOCKET, syscall.SO_RCVTIMEO, &tv); err != nil {
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return "", fmt.Errorf("设置接收超时失败: %v", err)
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}
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// 创建上下文，用于发送Router Solicitation并等待Router Advertisement
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ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
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defer cancel()
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// 发送Router Solicitation
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err = sendRouterSolicitation(fd, interfaceName)
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if err != nil {
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return "", fmt.Errorf("发送Router Solicitation失败: %v", err)
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}
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// 接收Router Advertisement
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buffer := make([]byte, 1500)
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for {
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select {
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case <-ctx.Done():
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return "", fmt.Errorf("等待Router Advertisement超时")
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default:
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n, _, err := syscall.Recvfrom(fd, buffer, 0)
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if err != nil {
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if err == syscall.EAGAIN || err == syscall.EWOULDBLOCK {
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continue
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}
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return "", fmt.Errorf("接收数据失败: %v", err)
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}
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// 确保收到的是ICMPv6消息
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if n < 4 {
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continue
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}
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// 检查是否为Router Advertisement
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if buffer[0] == ICMPv6RouterAdvertisement {
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// 解析数据包提取前缀长度
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prefixLengths := extractPrefixFromRAOption(buffer[:n])
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if len(prefixLengths) > 0 {
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// 返回第一个有效前缀长度
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return prefixLengths[0], nil
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}
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}
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}
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}
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}
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// 方法2：从ip命令获取前缀长度
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func getPrefixFromIPCommand(interfaceName string) (string, error) {
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cmd := exec.Command("ip", "-o", "-6", "addr", "show", interfaceName)
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output, err := cmd.Output()
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if err != nil {
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return "", err
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}
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// 匹配 inet6 地址和前缀长度
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re := regexp.MustCompile(`\s*inet6\s+([a-fA-F0-9:]+)/(\d+)\s+scope\s+global`)
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matches := re.FindAllStringSubmatch(string(output), -1)
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if len(matches) == 0 {
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return "", fmt.Errorf("未找到全局IPv6地址")
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}
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var prefixLens []string
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for _, match := range matches {
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ipv6Addr := match[1]
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// 排除非公网地址前缀
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if strings.HasPrefix(ipv6Addr, "fe80") || // 链路本地地址
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strings.HasPrefix(ipv6Addr, "::1") || // 回环地址
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strings.HasPrefix(ipv6Addr, "fc") || // 本地唯一地址
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strings.HasPrefix(ipv6Addr, "fd") || // 本地唯一地址
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strings.HasPrefix(ipv6Addr, "ff") { // 组播地址
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continue
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}
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// 提取 prefixlen
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if len(match) > 2 {
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prefixLens = append(prefixLens, match[2])
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}
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}
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if len(prefixLens) >= 1 {
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sort.Strings(prefixLens)
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return prefixLens[0], nil
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}
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return "", fmt.Errorf("未找到有效的IPv6前缀长度")
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}
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// Linux平台专用的配置文件获取方法
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func getPrefixFromConfigFiles() (string, error) {
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// 尝试从常见的网络配置文件中读取
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configFiles := []string{
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"/etc/network/interfaces",
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"/etc/netplan/01-netcfg.yaml",
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"/etc/netplan/50-cloud-init.yaml",
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"/etc/sysconfig/network-scripts/ifcfg-eth0",
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}
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for _, file := range configFiles {
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if _, err := os.Stat(file); err == nil {
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content, err := os.ReadFile(file)
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if err != nil {
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continue
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}
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// 在配置文件中查找IPv6前缀长度
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re := regexp.MustCompile(`(?i)(prefix-length|prefixlen|netmask)[\s:=]+(\d+)`)
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matches := re.FindStringSubmatch(string(content))
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if len(matches) >= 3 {
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return matches[2], nil
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}
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}
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}
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return "", fmt.Errorf("在配置文件中未找到IPv6前缀长度信息")
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}
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// 获取 IPv6 子网掩码 - Linux 实现
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func GetIPv6Mask(language string) (string, error) {
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// 首先检查是否有公网IPv6地址
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publicIPv6, err := getCurrentIPv6()
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if err != nil || publicIPv6 == "" {
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// 没有公网IPv6，返回空字符串
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return "", nil
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}
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// 获取网络接口
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interfaceName, err := getInterface()
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if err != nil || interfaceName == "" {
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return "", fmt.Errorf("获取网络接口失败: %v", err)
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}
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// 优先级1：尝试从RA报文获取前缀长度
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prefixLen, err := getPrefixFromRA(interfaceName)
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if err == nil && prefixLen != "" {
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return formatIPv6Mask(prefixLen, language), nil
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}
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// 优先级2：从ip命令获取前缀长度
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prefixLen, err = getPrefixFromIPCommand(interfaceName)
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if err == nil && prefixLen != "" {
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return formatIPv6Mask(prefixLen, language), nil
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}
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// 优先级3：从配置文件获取前缀长度
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prefixLen, err = getPrefixFromConfigFiles()
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if err == nil && prefixLen != "" {
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return formatIPv6Mask(prefixLen, language), nil
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}
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// 如果以上方法都失败但确实有公网IPv6，使用/128作为默认子网掩码
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return formatIPv6Mask("128", language), nil
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}
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