152 lines
3.3 KiB
Go
152 lines
3.3 KiB
Go
package dns
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import (
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"bufio"
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"encoding/json"
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"fmt"
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"os"
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"regexp"
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"strings"
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"time"
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)
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// DNSConfig DNS配置文件结构
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type DNSConfig struct {
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Records map[string]string `json:"records"` // 普通记录和泛解析记录
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Fallback bool `json:"fallback"` // 是否回退到系统DNS
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TTL int `json:"ttl"` // 缓存TTL，单位为秒
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}
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// LoadFromJSON 从JSON文件加载DNS配置
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func LoadFromJSON(filePath string) (*DNSConfig, error) {
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file, err := os.Open(filePath)
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if err != nil {
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return nil, fmt.Errorf("打开DNS配置文件失败: %w", err)
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}
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defer file.Close()
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config := &DNSConfig{
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Records: make(map[string]string),
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Fallback: true,
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TTL: 300, // 默认5分钟
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}
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decoder := json.NewDecoder(file)
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if err := decoder.Decode(config); err != nil {
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return nil, fmt.Errorf("解析DNS配置文件失败: %w", err)
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}
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return config, nil
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}
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// SaveToJSON 将DNS配置保存为JSON文件
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func (c *DNSConfig) SaveToJSON(filePath string) error {
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file, err := os.Create(filePath)
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if err != nil {
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return fmt.Errorf("创建DNS配置文件失败: %w", err)
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}
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defer file.Close()
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encoder := json.NewEncoder(file)
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encoder.SetIndent("", " ")
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if err := encoder.Encode(c); err != nil {
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return fmt.Errorf("保存DNS配置文件失败: %w", err)
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}
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return nil
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}
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// 用于解析hosts文件中的IP:端口格式
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var ipPortRegex = regexp.MustCompile(`^([0-9.]+)(?::(\d+))?$`)
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// 检查是否为通配符域名
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func isWildcardDomain(domain string) bool {
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return strings.Contains(domain, "*")
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}
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// LoadFromHostsFile 从hosts文件格式加载DNS配置
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func LoadFromHostsFile(filePath string) (*DNSConfig, error) {
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file, err := os.Open(filePath)
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if err != nil {
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return nil, fmt.Errorf("打开hosts文件失败: %w", err)
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}
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defer file.Close()
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config := &DNSConfig{
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Records: make(map[string]string),
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Fallback: true,
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TTL: 300, // 默认5分钟
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}
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scanner := bufio.NewScanner(file)
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lineNum := 0
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for scanner.Scan() {
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lineNum++
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line := strings.TrimSpace(scanner.Text())
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// 跳过空行和注释
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if line == "" || strings.HasPrefix(line, "#") {
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continue
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}
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fields := strings.Fields(line)
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if len(fields) < 2 {
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continue // 行格式不正确，跳过
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}
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ipPortStr := fields[0]
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domains := fields[1:]
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// 解析IP和可能的端口
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matches := ipPortRegex.FindStringSubmatch(ipPortStr)
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if matches == nil {
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continue // IP格式不正确，跳过
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}
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ip := matches[1]
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portStr := matches[2]
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// 构造记录值
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value := ip
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if portStr != "" {
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value = ip + ":" + portStr
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}
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for _, domain := range domains {
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// 跳过注释
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if strings.HasPrefix(domain, "#") {
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break
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}
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// 支持通配符和普通域名
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config.Records[domain] = value
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}
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}
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if err := scanner.Err(); err != nil {
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return nil, fmt.Errorf("读取hosts文件失败: %w", err)
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}
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return config, nil
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}
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// NewResolverFromConfig 从配置创建解析器
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func NewResolverFromConfig(config *DNSConfig) *CustomResolver {
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var ttl time.Duration
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if config.TTL > 0 {
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ttl = time.Duration(config.TTL) * time.Second
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} else {
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ttl = 5 * time.Minute // 默认5分钟
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}
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resolver := NewResolver(
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WithFallback(config.Fallback),
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WithTTL(ttl),
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)
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// 加载记录
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resolver.LoadFromMap(config.Records)
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return resolver
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}
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