fix: 修复ipv6前缀长度获取影响宿主机配置的问题

2025-10-11 19:40:15 +08:00 · 2025-03-31 12:22:28 +00:00
parent 4b16a1bc8b
commit babcb62e02
2 changed files with 251 additions and 97 deletions
--- a/README.md
+++ b/README.md
@@ -18,7 +18,6 @@ Include: https://github.com/oneclickvirt/gostun

 ## TODO

- [ ] 目前IPV4的CIDR已加入识别，IPV6的CIDR待处理加入识别
 - [ ] 适配MACOS系统的识别

 ## Usage
--- a/ipv6/ipv6.go
+++ b/ipv6/ipv6.go
@@ -1,11 +1,15 @@
 package ipv6

 import (
+	"context"
 	"fmt"
+	"net"
+	"os"
 	"os/exec"
 	"regexp"
 	"sort"
 	"strings"
+	"syscall"
 	"time"
 )

@@ -19,7 +23,7 @@ func getInterface() (string, error) {
 	return strings.TrimSpace(string(output)), nil
 }

-// 获取当前的 IPv6 地址
+// 获取当前的公网 IPv6 地址
 func getCurrentIPv6() (string, error) {
 	cmd := exec.Command("curl", "-s", "-6", "-m", "5", "ipv6.ip.sb")
 	output, err := cmd.Output()
@@ -29,58 +33,191 @@ func getCurrentIPv6() (string, error) {
 	return strings.TrimSpace(string(output)), nil
 }

-// 添加 IPv6 地址到指定接口
-func addIPv6(interfaceName, ipv6 string) error {
-	cmd := exec.Command("ip", "addr", "add", ipv6+"/128", "dev", interfaceName)
-	return cmd.Run()
+// Router Advertisement前缀选项类型
+const (
+	ICMPv6RouterAdvertisement = 134
+	ICMPv6OptionPrefix        = 3
+)
+
+// ICMPv6报文头部结构
+type ICMPv6Header struct {
+	Type     uint8
+	Code     uint8
+	Checksum uint16
 }

-// 删除指定接口上的 IPv6 地址
-func delIPv6(interfaceName, ipv6 string) error {
-	cmd := exec.Command("ip", "addr", "del", ipv6+"/128", "dev", interfaceName)
-	return cmd.Run()
+// Router Advertisement报文结构
+type RouterAdvertisement struct {
+	CurHopLimit    uint8
+	Flags          uint8
+	RouterLifetime uint16
+	ReachableTime  uint32
+	RetransTimer   uint32
+	Options        []byte
 }

-// ifconfig
-// func getIPv6PrefixLength(interfaceName string) (string, error) {
-// 	cmd := exec.Command("ifconfig", interfaceName)
-// 	output, err := cmd.Output()
-// 	if err != nil {
-// 		return "", err
-// 	}
-// 	// 匹配 inet6 地址和前缀长度
-// 	re := regexp.MustCompile(`\s*inet6\s+([a-fA-F0-9:]+)\s+prefixlen\s+(\d+)\s*`)
-// 	matches := re.FindAllStringSubmatch(string(output), -1)
-// 	if len(matches) == 0 {
-// 		return "", nil
-// 	}
-// 	var prefixLens []string
-// 	for _, match := range matches {
-// 		ipv6Addr := match[1]
-// 		// 排除非公网地址前缀
-// 		if strings.HasPrefix(ipv6Addr, "fe80") ||    // 链路本地地址
-// 			strings.HasPrefix(ipv6Addr, "::1") ||     // 回环地址
-// 			strings.HasPrefix(ipv6Addr, "fc") ||      // 本地唯一地址
-// 			strings.HasPrefix(ipv6Addr, "fd") ||      // 本地唯一地址
-// 			strings.HasPrefix(ipv6Addr, "ff") {       // 组播地址
-// 			continue
-// 		}
-// 		// 提取 prefixlen
-// 		if len(match) > 2 {
-// 			prefixLens = append(prefixLens, match[2])
-// 		}
-// 	}
-// 	if len(prefixLens) >= 2 {
-// 		sort.Strings(prefixLens)
-// 		return prefixLens[0], nil
-// 	} else if len(prefixLens) == 1 {
-// 		return prefixLens[0], nil
-// 	}
-// 	return "", nil
-// }
+// 前缀信息选项结构
+type PrefixInfoOption struct {
+	Type              uint8
+	Length            uint8
+	PrefixLength      uint8
+	Flags             uint8
+	ValidLifetime     uint32
+	PreferredLifetime uint32
+	Reserved          uint32
+	Prefix            [16]byte
+}

-// 获取接口的子网掩码前缀 ip
-func getIPv6PrefixLength(interfaceName string) (string, error) {
+// 从RA报文中提取前缀长度信息
+func extractPrefixFromRAOption(data []byte) []string {
+	var prefixLengths []string
+	// 跳过ICMPv6头部(4字节)和Router Advertisement基本信息(12字节)
+	optionStart := 16
+	// 遍历所有选项
+	for optionStart < len(data) {
+		// 确保有足够的数据可读
+		if optionStart+2 > len(data) {
+			break
+		}
+		optionType := data[optionStart]
+		optionLen := data[optionStart+1] * 8 // 长度以8字节为单位
+		// 确保选项长度有效
+		if optionLen == 0 || optionStart+int(optionLen) > len(data) {
+			break
+		}
+		// 解析前缀信息选项
+		if optionType == ICMPv6OptionPrefix && optionLen >= 32 {
+			// 前缀长度在选项开始后2字节处
+			prefixLen := data[optionStart+2]
+			// 前缀值从选项开始后16字节处
+			prefixStart := optionStart + 16
+			if prefixStart+16 <= len(data) {
+				var prefix [16]byte
+				copy(prefix[:], data[prefixStart:prefixStart+16])
+				// 排除非全局单播地址
+				if !isNonGlobalPrefix(prefix) {
+					prefixLengths = append(prefixLengths, fmt.Sprintf("%d", prefixLen))
+				}
+			}
+		}
+		optionStart += int(optionLen)
+	}
+	return prefixLengths
+}
+
+// 判断是否为非全局单播地址前缀
+func isNonGlobalPrefix(prefix [16]byte) bool {
+	// 链路本地地址 fe80::/10
+	if prefix[0] == 0xfe && (prefix[1]&0xc0) == 0x80 {
+		return true
+	}
+	// 唯一本地地址 fc00::/7
+	if (prefix[0] & 0xfe) == 0xfc {
+		return true
+	}
+	// 回环地址 ::1
+	if prefix[0] == 0 && prefix[1] == 0 && prefix[15] == 1 {
+		return true
+	}
+	// 组播地址 ff00::/8
+	if prefix[0] == 0xff {
+		return true
+	}
+	return false
+}
+
+// 方法1：尝试原生实现从Router Advertisement获取前缀长度
+func getPrefixFromRA(interfaceName string) (string, error) {
+	// 尝试先用radvdump，如果存在的话
+	radvdumpPath, err := exec.LookPath("radvdump")
+	if err == nil && radvdumpPath != "" {
+		cmd := exec.Command("radvdump", "-i", interfaceName)
+		output, err := cmd.Output()
+		if err == nil {
+			re := regexp.MustCompile(`(?i)prefix\s+([a-fA-F0-9:]+)/(\d+)`)
+			matches := re.FindAllStringSubmatch(string(output), -1)
+			for _, match := range matches {
+				prefix := match[1]
+				prefixLen := match[2]
+				// 排除非公网地址前缀
+				if !strings.HasPrefix(prefix, "fe80") &&
+					!strings.HasPrefix(prefix, "::1") &&
+					!strings.HasPrefix(prefix, "fc") &&
+					!strings.HasPrefix(prefix, "fd") &&
+					!strings.HasPrefix(prefix, "ff") {
+					return prefixLen, nil
+				}
+			}
+		}
+	}
+	// 如果radvdump不可用或未找到有效前缀，使用原生实现
+	intf, err := net.InterfaceByName(interfaceName)
+	if err != nil {
+		return "", fmt.Errorf("获取网络接口失败: %v", err)
+	}
+	// 创建原始套接字接收ICMPv6消息
+	fd, err := syscall.Socket(syscall.AF_INET6, syscall.SOCK_RAW, syscall.IPPROTO_ICMPV6)
+	if err != nil {
+		return "", fmt.Errorf("创建原始套接字失败: %v", err)
+	}
+	defer syscall.Close(fd)
+	// 绑定到指定接口
+	if err := syscall.SetsockoptInt(fd, syscall.SOL_SOCKET, syscall.SO_BINDTODEVICE, intf.Index); err != nil {
+		return "", fmt.Errorf("绑定套接字到接口失败: %v", err)
+	}
+	// 设置过滤器，只接收Router Advertisement消息
+	if err := syscall.SetsockoptInt(fd, syscall.IPPROTO_IPV6, syscall.IPV6_RECVPKTINFO, 1); err != nil {
+		return "", fmt.Errorf("设置套接字选项失败: %v", err)
+	}
+	// 设置接收超时
+	tv := syscall.Timeval{
+		Sec:  5, // 5秒超时
+		Usec: 0,
+	}
+	if err := syscall.SetsockoptTimeval(fd, syscall.SOL_SOCKET, syscall.SO_RCVTIMEO, &tv); err != nil {
+		return "", fmt.Errorf("设置接收超时失败: %v", err)
+	}
+	// 创建上下文，用于发送Router Solicitation并等待Router Advertisement
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+	// 发送Router Solicitation
+	go func() {
+		// 实际应用中可能需要构造并发送Router Solicitation消息
+		// 这里为简化代码，仅依赖网络上周期性的Router Advertisement
+	}()
+	// 接收Router Advertisement
+	buffer := make([]byte, 1500)
+	for {
+		select {
+		case <-ctx.Done():
+			return "", fmt.Errorf("等待Router Advertisement超时")
+		default:
+			n, _, err := syscall.Recvfrom(fd, buffer, 0)
+			if err != nil {
+				if err == syscall.EAGAIN || err == syscall.EWOULDBLOCK {
+					continue
+				}
+				return "", fmt.Errorf("接收数据失败: %v", err)
+			}
+			// 确保收到的是ICMPv6消息
+			if n < 4 {
+				continue
+			}
+			// 检查是否为Router Advertisement
+			if buffer[0] == ICMPv6RouterAdvertisement {
+				// 解析数据包提取前缀长度
+				prefixLengths := extractPrefixFromRAOption(buffer[:n])
+				if len(prefixLengths) > 0 {
+					// 返回第一个有效前缀长度
+					return prefixLengths[0], nil
+				}
+			}
+		}
+	}
+}
+
+// 方法2：从ip命令获取前缀长度
+func getPrefixFromIPCommand(interfaceName string) (string, error) {
 	cmd := exec.Command("ip", "-o", "-6", "addr", "show", interfaceName)
 	output, err := cmd.Output()
 	if err != nil {
@@ -90,7 +227,7 @@ func getIPv6PrefixLength(interfaceName string) (string, error) {
 	re := regexp.MustCompile(`\s*inet6\s+([a-fA-F0-9:]+)/(\d+)\s+scope\s+global`)
 	matches := re.FindAllStringSubmatch(string(output), -1)
 	if len(matches) == 0 {
-		return "", nil
+		return "", fmt.Errorf("未找到全局IPv6地址")
 	}
 	var prefixLens []string
 	for _, match := range matches {
@@ -108,62 +245,80 @@ func getIPv6PrefixLength(interfaceName string) (string, error) {
 			prefixLens = append(prefixLens, match[2])
 		}
 	}
-	if len(prefixLens) >= 2 {
+	if len(prefixLens) >= 1 {
 		sort.Strings(prefixLens)
 		return prefixLens[0], nil
-	} else if len(prefixLens) == 1 {
-		return prefixLens[0], nil
 	}
-	return "", nil
+	return "", fmt.Errorf("未找到有效的IPv6前缀长度")
+}
+
+// 方法3：从配置文件获取前缀长度
+func getPrefixFromConfigFiles() (string, error) {
+	// 尝试从常见的网络配置文件中读取
+	configFiles := []string{
+		"/etc/network/interfaces",
+		"/etc/netplan/01-netcfg.yaml",
+		"/etc/netplan/50-cloud-init.yaml",
+		"/etc/sysconfig/network-scripts/ifcfg-eth0",
+	}
+	for _, file := range configFiles {
+		if _, err := os.Stat(file); err == nil {
+			content, err := os.ReadFile(file)
+			if err != nil {
+				continue
+			}
+			// 在配置文件中查找IPv6前缀长度
+			re := regexp.MustCompile(`(?i)(prefix-length|prefixlen|netmask)[\s:=]+(\d+)`)
+			matches := re.FindStringSubmatch(string(content))
+			if len(matches) >= 3 {
+				return matches[2], nil
+			}
+		}
+	}
+	return "", fmt.Errorf("在配置文件中未找到IPv6前缀长度信息")
 }

+// 获取 IPv6 子网掩码
 // 获取 IPv6 子网掩码
 func GetIPv6Mask(language string) (string, error) {
+	// 首先检查是否有公网IPv6地址
+	publicIPv6, err := getCurrentIPv6()
+	if err != nil || publicIPv6 == "" {
+		// 没有公网IPv6，返回空字符串
+		return "", nil
+	}
 	// 获取网络接口
 	interfaceName, err := getInterface()
 	if err != nil || interfaceName == "" {
-		return "", fmt.Errorf("Failed to get network interface: %v", err)
+		return "", fmt.Errorf("获取网络接口失败: %v", err)
 	}
-	// fmt.Println(interfaceName)
-	// 获取当前 IPv6 地址
-	currentIPv6, err := getCurrentIPv6()
-	if err != nil || currentIPv6 == "" {
-		return "", fmt.Errorf("Failed to get current IPv6 address: %v", err)
+	// 优先级1：尝试从RA报文获取前缀长度
+	prefixLen, err := getPrefixFromRA(interfaceName)
+	if err == nil && prefixLen != "" {
+		if language == "en" {
+			return fmt.Sprintf(" IPv6 Mask           : /%s", prefixLen), nil
 		}
-	// 生成新的 IPv6 地址
-	newIPv6 := currentIPv6[:strings.LastIndex(currentIPv6, ":")] + ":3"
-	// 添加新的 IPv6 地址
-	if err := addIPv6(interfaceName, newIPv6); err != nil {
-		return "", fmt.Errorf("Failed to add IPv6 address: %v", err)
+		return fmt.Sprintf(" IPv6 子网掩码       : /%s", prefixLen), nil
 	}
-	time.Sleep(5 * time.Second)
-	// 获取更新后的 IPv6 地址
-	updatedIPv6, err := getCurrentIPv6()
-	if err != nil {
-		return "", fmt.Errorf("Failed to get updated IPv6 address: %v", err)
+	// 优先级2：从ip命令获取前缀长度
+	prefixLen, err = getPrefixFromIPCommand(interfaceName)
+	if err == nil && prefixLen != "" {
+		if language == "en" {
+			return fmt.Sprintf(" IPv6 Mask           : /%s", prefixLen), nil
 		}
-	// 删除添加的 IPv6 地址
-	if err := delIPv6(interfaceName, newIPv6); err != nil {
-		return "", fmt.Errorf("Failed to delete IPv6 address: %v", err)
+		return fmt.Sprintf(" IPv6 子网掩码       : /%s", prefixLen), nil
 	}
-	time.Sleep(5 * time.Second)
-	// 获取子网掩码前缀长度
-	ipv6Prefixlen, err := getIPv6PrefixLength(interfaceName)
-	if err != nil {
-		return "", fmt.Errorf("Failed to get IPv6 prefix length: %v", err)
+	// 优先级3：从配置文件获取前缀长度
+	prefixLen, err = getPrefixFromConfigFiles()
+	if err == nil && prefixLen != "" {
+		if language == "en" {
+			return fmt.Sprintf(" IPv6 Mask           : /%s", prefixLen), nil
 		}
-	if ipv6Prefixlen == "" {
-		return "", fmt.Errorf("get IPv6 prefix length is null")
+		return fmt.Sprintf(" IPv6 子网掩码       : /%s", prefixLen), nil
 	}
-	// 输出结果
-	if updatedIPv6 == currentIPv6 || updatedIPv6 == "" {
+	// 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
 	if language == "en" {
 		return " IPv6 Mask           : /128", nil
 	}
 	return " IPv6 子网掩码       : /128", nil
-	}
-	if language == "en" {
-		return fmt.Sprintf(" IPv6 Mask           : /%s\n", ipv6Prefixlen), nil
-	}
-	return fmt.Sprintf(" IPv6 子网掩码       : /%s\n", ipv6Prefixlen), nil
 }