新建DNS服务器
This commit is contained in:
Alex Yang
396
dns/server.go
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396
dns/server.go
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@@ -0,0 +1,396 @@
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package dns
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import (
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"context"
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"fmt"
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"net"
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"sort"
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"sync"
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"time"
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"dns-server/config"
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"dns-server/logger"
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"dns-server/shield"
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"github.com/miekg/dns"
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)
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// BlockedDomain 屏蔽域名统计
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type BlockedDomain struct {
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Domain string
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Count int64
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LastSeen time.Time
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}
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// Server DNS服务器
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type Server struct {
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config *config.DNSConfig
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shieldConfig *config.ShieldConfig
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shieldManager *shield.ShieldManager
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server *dns.Server
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resolver *dns.Client
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ctx context.Context
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cancel context.CancelFunc
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statsMutex sync.Mutex
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stats *Stats
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blockedDomainsMutex sync.RWMutex
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blockedDomains map[string]*BlockedDomain
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hourlyStatsMutex sync.RWMutex
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hourlyStats map[string]int64 // 按小时统计屏蔽数量
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}
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// Stats DNS服务器统计信息
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type Stats struct {
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Queries int64
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Blocked int64
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Allowed int64
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Errors int64
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LastQuery time.Time
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}
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// NewServer 创建DNS服务器实例
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func NewServer(config *config.DNSConfig, shieldConfig *config.ShieldConfig, shieldManager *shield.ShieldManager) *Server {
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ctx, cancel := context.WithCancel(context.Background())
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return &Server{
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config: config,
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shieldConfig: shieldConfig,
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shieldManager: shieldManager,
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resolver: &dns.Client{
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Net: "udp",
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Timeout: time.Duration(config.Timeout) * time.Millisecond,
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},
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ctx: ctx,
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cancel: cancel,
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stats: &Stats{
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Queries: 0,
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Blocked: 0,
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Allowed: 0,
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Errors: 0,
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},
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blockedDomains: make(map[string]*BlockedDomain),
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hourlyStats: make(map[string]int64),
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}
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}
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// Start 启动DNS服务器
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func (s *Server) Start() error {
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s.server = &dns.Server{
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Addr: fmt.Sprintf(":%d", s.config.Port),
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Net: "udp",
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Handler: dns.HandlerFunc(s.handleDNSRequest),
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}
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// 启动TCP服务器（用于大型响应）
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tcpServer := &dns.Server{
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Addr: fmt.Sprintf(":%d", s.config.Port),
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Net: "tcp",
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Handler: dns.HandlerFunc(s.handleDNSRequest),
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}
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// 启动UDP服务
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go func() {
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logger.Info(fmt.Sprintf("DNS UDP服务器启动，监听端口: %d", s.config.Port))
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if err := s.server.ListenAndServe(); err != nil {
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logger.Error("DNS UDP服务器启动失败", "error", err)
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s.cancel()
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}
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}()
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// 启动TCP服务
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go func() {
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logger.Info(fmt.Sprintf("DNS TCP服务器启动，监听端口: %d", s.config.Port))
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if err := tcpServer.ListenAndServe(); err != nil {
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logger.Error("DNS TCP服务器启动失败", "error", err)
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s.cancel()
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}
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}()
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// 等待停止信号
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<-s.ctx.Done()
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return nil
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}
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// Stop 停止DNS服务器
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func (s *Server) Stop() {
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if s.server != nil {
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s.server.Shutdown()
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}
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s.cancel()
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logger.Info("DNS服务器已停止")
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}
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// handleDNSRequest 处理DNS请求
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func (s *Server) handleDNSRequest(w dns.ResponseWriter, r *dns.Msg) {
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s.updateStats(func(stats *Stats) {
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stats.Queries++
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stats.LastQuery = time.Now()
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})
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// 只处理递归查询
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if r.RecursionDesired == false {
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response := new(dns.Msg)
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response.SetReply(r)
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response.RecursionAvailable = true
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response.SetRcode(r, dns.RcodeRefused)
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w.WriteMsg(response)
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return
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}
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// 获取查询域名
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var domain string
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if len(r.Question) > 0 {
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domain = r.Question[0].Name
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// 移除末尾的点
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if len(domain) > 0 && domain[len(domain)-1] == '.' {
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domain = domain[:len(domain)-1]
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}
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}
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logger.Debug("接收到DNS查询", "domain", domain, "type", r.Question[0].Qtype, "client", w.RemoteAddr())
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// 检查hosts文件是否有匹配
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if ip, exists := s.shieldManager.GetHostsIP(domain); exists {
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s.handleHostsResponse(w, r, ip)
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return
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}
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// 检查是否被屏蔽
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if s.shieldManager.IsBlocked(domain) {
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s.handleBlockedResponse(w, r, domain)
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return
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}
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// 转发到上游DNS服务器
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s.forwardDNSRequest(w, r, domain)
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}
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// handleHostsResponse 处理hosts文件匹配的响应
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func (s *Server) handleHostsResponse(w dns.ResponseWriter, r *dns.Msg, ip string) {
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response := new(dns.Msg)
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response.SetReply(r)
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response.RecursionAvailable = true
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if len(r.Question) > 0 {
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q := r.Question[0]
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answer := new(dns.A)
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answer.Hdr = dns.RR_Header{
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Name: q.Name,
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Rrtype: dns.TypeA,
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Class: dns.ClassINET,
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Ttl: 300,
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}
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answer.A = net.ParseIP(ip)
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response.Answer = append(response.Answer, answer)
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}
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w.WriteMsg(response)
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s.updateStats(func(stats *Stats) {
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stats.Allowed++
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})
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}
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// handleBlockedResponse 处理被屏蔽的域名响应
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func (s *Server) handleBlockedResponse(w dns.ResponseWriter, r *dns.Msg, domain string) {
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logger.Info("域名被屏蔽", "domain", domain, "client", w.RemoteAddr())
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// 更新被屏蔽域名统计
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s.updateBlockedDomainStats(domain)
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// 更新总体统计
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s.updateStats(func(stats *Stats) {
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stats.Blocked++
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})
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response := new(dns.Msg)
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response.SetReply(r)
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response.RecursionAvailable = true
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// 获取屏蔽方法配置
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blockMethod := "NXDOMAIN" // 默认值
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customBlockIP := "" // 默认值
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// 从Server结构体的shieldConfig字段获取配置
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if s.shieldConfig != nil {
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blockMethod = s.shieldConfig.BlockMethod
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customBlockIP = s.shieldConfig.CustomBlockIP
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}
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// 根据屏蔽方法返回不同的响应
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switch blockMethod {
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case "refused":
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// 返回拒绝查询响应
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response.SetRcode(r, dns.RcodeRefused)
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case "emptyIP":
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// 返回空IP响应
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if len(r.Question) > 0 && r.Question[0].Qtype == dns.TypeA {
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answer := new(dns.A)
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answer.Hdr = dns.RR_Header{
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Name: r.Question[0].Name,
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Rrtype: dns.TypeA,
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Class: dns.ClassINET,
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Ttl: 300,
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}
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answer.A = net.ParseIP("0.0.0.0") // 空IP
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response.Answer = append(response.Answer, answer)
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}
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case "customIP":
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// 返回自定义IP响应
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if len(r.Question) > 0 && r.Question[0].Qtype == dns.TypeA && customBlockIP != "" {
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answer := new(dns.A)
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answer.Hdr = dns.RR_Header{
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Name: r.Question[0].Name,
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Rrtype: dns.TypeA,
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Class: dns.ClassINET,
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Ttl: 300,
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}
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answer.A = net.ParseIP(customBlockIP)
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response.Answer = append(response.Answer, answer)
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}
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case "NXDOMAIN", "":
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fallthrough // 默认使用NXDOMAIN
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default:
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// 返回NXDOMAIN响应（域名不存在）
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response.SetRcode(r, dns.RcodeNameError)
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}
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w.WriteMsg(response)
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s.updateStats(func(stats *Stats) {
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stats.Blocked++
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})
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}
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// forwardDNSRequest 转发DNS请求到上游服务器
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func (s *Server) forwardDNSRequest(w dns.ResponseWriter, r *dns.Msg, domain string) {
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// 尝试所有上游DNS服务器
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for _, upstream := range s.config.UpstreamDNS {
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response, rtt, err := s.resolver.Exchange(r, upstream)
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if err == nil && response != nil && response.Rcode == dns.RcodeSuccess {
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// 设置递归可用标志
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response.RecursionAvailable = true
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w.WriteMsg(response)
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logger.Debug("DNS查询成功", "domain", domain, "rtt", rtt, "server", upstream)
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s.updateStats(func(stats *Stats) {
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stats.Allowed++
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})
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return
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}
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}
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// 所有上游服务器都失败，返回服务器失败错误
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response := new(dns.Msg)
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response.SetReply(r)
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response.RecursionAvailable = true
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response.SetRcode(r, dns.RcodeServerFailure)
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w.WriteMsg(response)
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logger.Error("DNS查询失败", "domain", domain)
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s.updateStats(func(stats *Stats) {
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stats.Errors++
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})
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}
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// updateBlockedDomainStats 更新被屏蔽域名统计
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func (s *Server) updateBlockedDomainStats(domain string) {
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// 更新被屏蔽域名计数
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s.blockedDomainsMutex.Lock()
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defer s.blockedDomainsMutex.Unlock()
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if entry, exists := s.blockedDomains[domain]; exists {
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entry.Count++
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entry.LastSeen = time.Now()
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} else {
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s.blockedDomains[domain] = &BlockedDomain{
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Domain: domain,
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Count: 1,
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LastSeen: time.Now(),
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}
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}
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// 更新小时统计
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hourKey := time.Now().Format("2006-01-02-15")
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s.hourlyStats[hourKey]++
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}
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// updateStats 更新统计信息
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func (s *Server) updateStats(update func(*Stats)) {
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s.statsMutex.Lock()
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defer s.statsMutex.Unlock()
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update(s.stats)
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}
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// GetStats 获取DNS服务器统计信息
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func (s *Server) GetStats() *Stats {
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s.statsMutex.Lock()
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defer s.statsMutex.Unlock()
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// 返回统计信息的副本
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return &Stats{
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Queries: s.stats.Queries,
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Blocked: s.stats.Blocked,
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Allowed: s.stats.Allowed,
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Errors: s.stats.Errors,
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LastQuery: s.stats.LastQuery,
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}
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}
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// GetTopBlockedDomains 获取TOP屏蔽域名列表
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func (s *Server) GetTopBlockedDomains(limit int) []BlockedDomain {
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s.blockedDomainsMutex.RLock()
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defer s.blockedDomainsMutex.RUnlock()
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// 转换为切片
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domains := make([]BlockedDomain, 0, len(s.blockedDomains))
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for _, entry := range s.blockedDomains {
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domains = append(domains, *entry)
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}
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// 按计数排序
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sort.Slice(domains, func(i, j int) bool {
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return domains[i].Count > domains[j].Count
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})
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// 返回限制数量
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if len(domains) > limit {
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return domains[:limit]
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}
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return domains
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}
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// GetRecentBlockedDomains 获取最近屏蔽的域名列表
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func (s *Server) GetRecentBlockedDomains(limit int) []BlockedDomain {
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s.blockedDomainsMutex.RLock()
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defer s.blockedDomainsMutex.RUnlock()
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// 转换为切片
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domains := make([]BlockedDomain, 0, len(s.blockedDomains))
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for _, entry := range s.blockedDomains {
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domains = append(domains, *entry)
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}
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// 按时间排序
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sort.Slice(domains, func(i, j int) bool {
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return domains[i].LastSeen.After(domains[j].LastSeen)
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})
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// 返回限制数量
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if len(domains) > limit {
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return domains[:limit]
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}
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return domains
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}
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// GetHourlyStats 获取24小时屏蔽统计
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func (s *Server) GetHourlyStats() map[string]int64 {
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s.hourlyStatsMutex.RLock()
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defer s.hourlyStatsMutex.RUnlock()
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// 返回副本
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result := make(map[string]int64)
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for k, v := range s.hourlyStats {
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result[k] = v
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}
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return result
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}
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