aixiao
4060e83686
docs(readme): 重构 README 文档结构与内容以提升可读性 - 更新项目标题图标并优化描述语句 - 重新组织特性列表为表格形式，增加 ECS 剥离、黑名单过滤等功能说明 - 补充快速开始章节，细化源码构建与 Docker 使用方式 - 调整参数说明表，新增黑名单相关配置项及缓存条目限制 - 增加缓存机制详解、黑名单功能使用示例与架构图 - 更新开发依赖信息与推荐编译参数 - 修正作者信息展示格式并添加仓库链接 feat(cache): 改进缓存键生成逻辑与 EDNS 元数据处理 - 使用 dns.CanonicalName 规范化域名避免重复缓存键 - 缓存条目中保存 EDNS 扩展信息（version, rcode, EDE） - 修复缓存读取函数返回值，传递完整缓存元数据 - 调整 TTL 计算优先级，仅在必要时检查 Extra 区域 - 黑名单匹配提前拦截请求，跳过上游查询 - 启动日志中显示黑名单规则数量与返回码设置 ```
677 lines
17 KiB
Go
677 lines
17 KiB
Go
package main
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import (
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"context"
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"crypto/tls"
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"flag"
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"fmt"
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"log"
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"math/rand"
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"os"
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"os/signal"
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"strings"
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"sync"
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"syscall"
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"time"
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"github.com/miekg/dns"
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lru "github.com/hashicorp/golang-lru/v2"
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)
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/******************************************************************
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* 日志初始化
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******************************************************************/
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func initLogger(verbose bool) {
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flags := log.Ldate | log.Ltime | log.Lmicroseconds
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if verbose {
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flags |= log.Lshortfile
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}
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log.SetFlags(flags)
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}
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/******************************************************************
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* 缓存结构（支持 TTL + LRU）
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******************************************************************/
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type cacheEntry struct {
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msg *dns.Msg
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expireAt time.Time
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// EDNS metadata (to reproduce Extended RCODE / EDE on cache hits)
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ednsPresent bool
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ednsVersion uint8
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ednsExtRcode uint16
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ednsEDE []*dns.EDNS0_EDE
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}
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var (
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cache *lru.Cache[string, *cacheEntry]
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cacheMutex sync.RWMutex
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)
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const (
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cacheCleanupInterval = 5 * time.Minute
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defaultCacheSize = 10000 // 默认最大缓存条目数
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)
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// startCacheCleaner 定期清理过期缓存（修复：在删除前二次校验）
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func startCacheCleaner(ctx context.Context) {
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go func() {
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ticker := time.NewTicker(cacheCleanupInterval)
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defer ticker.Stop()
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for {
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select {
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case <-ctx.Done():
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return
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case <-ticker.C:
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now := time.Now()
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var toDelete []string
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cacheMutex.RLock()
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for _, k := range cache.Keys() {
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if v, ok := cache.Peek(k); ok && now.After(v.expireAt) {
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toDelete = append(toDelete, k)
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}
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}
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cacheMutex.RUnlock()
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if len(toDelete) > 0 {
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pruned := 0
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cacheMutex.Lock()
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for _, k := range toDelete {
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if v, ok := cache.Peek(k); ok && now.After(v.expireAt) {
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cache.Remove(k)
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pruned++
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}
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}
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cacheMutex.Unlock()
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if pruned > 0 {
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log.Printf("[cache] cleaned %d expired entries", pruned)
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}
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}
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}
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}
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}()
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}
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func cacheKeyFromMsg(q dns.Question, do, cd bool) string {
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var b strings.Builder
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b.Grow(len(q.Name) + 32)
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// 采用规范化域名，避免尾随点/IDNA/大小写造成的重复键
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b.WriteString(dns.CanonicalName(q.Name))
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b.WriteString("|T=")
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b.WriteString(dns.TypeToString[q.Qtype])
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b.WriteString("|C=")
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b.WriteString(dns.ClassToString[q.Qclass])
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if do {
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b.WriteString("|DO")
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}
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if cd {
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b.WriteString("|CD")
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}
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return b.String()
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}
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func isPseudo(rr dns.RR) bool {
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switch rr.(type) {
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case *dns.OPT, *dns.TSIG:
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return true
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default:
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return false
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}
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}
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// clone and extract EDNS metadata (present, version, ext-rcode, all EDEs)
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func cloneEDE(in *dns.EDNS0_EDE) *dns.EDNS0_EDE {
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if in == nil {
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return nil
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}
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cp := *in
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return &cp
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}
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func extractEDNSMeta(m *dns.Msg) (present bool, version uint8, ext uint16, ede []*dns.EDNS0_EDE) {
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if o := m.IsEdns0(); o != nil {
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present = true
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version = o.Version()
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ext = uint16(o.ExtendedRcode())
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for _, opt := range o.Option {
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if e, ok := opt.(*dns.EDNS0_EDE); ok {
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ede = append(ede, cloneEDE(e))
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}
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}
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}
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return
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}
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// 读取缓存（修复：Get 在写锁下；在锁外调整 TTL；返回 EDNS 元数据）
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func tryCacheRead(key string) (*dns.Msg, *cacheEntry, bool) {
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now := time.Now()
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cacheMutex.Lock()
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e, ok := cache.Get(key) // Get 会更新 LRU，必须在写锁下
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if !ok {
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cacheMutex.Unlock()
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return nil, nil, false
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}
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if now.After(e.expireAt) {
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cache.Remove(key)
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cacheMutex.Unlock()
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return nil, nil, false
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}
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// 拷贝副本，在锁外改 TTL，减少临界区时间
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out := e.msg.Copy()
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expireAt := e.expireAt
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cacheMutex.Unlock()
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remaining := uint32(expireAt.Sub(now).Seconds())
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if remaining == 0 {
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cacheMutex.Lock()
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cache.Remove(key)
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cacheMutex.Unlock()
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return nil, nil, false
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}
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for _, sec := range [][]dns.RR{out.Answer, out.Ns, out.Extra} {
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for _, rr := range sec {
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if isPseudo(rr) {
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continue
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}
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if rr.Header().Ttl > remaining {
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rr.Header().Ttl = remaining
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}
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}
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}
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return out, e, true
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}
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// 计算负面 TTL
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// hasAnswerForType 判断报文中是否存在回答“请求类型”的 RRset
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func hasAnswerForType(m *dns.Msg, q dns.Question) bool {
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for _, rr := range m.Answer {
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h := rr.Header()
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if h.Rrtype == q.Qtype && strings.EqualFold(h.Name, q.Name) {
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return true
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}
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}
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return false
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}
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// 计算负面 TTL（修复：正确识别 NODATA，包括 CNAME 等场景）
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func negativeTTL(m *dns.Msg, maxTTL time.Duration) (uint32, bool) {
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// NXDOMAIN：肯定是负面
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if m.Rcode != dns.RcodeNameError {
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// 不是 NXDOMAIN，则仅当 NOERROR 但没有“匹配 QTYPE 的答案”时才是 NODATA
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if m.Rcode != dns.RcodeSuccess || len(m.Question) == 0 || hasAnswerForType(m, m.Question[0]) {
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return 0, false
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}
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}
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// 按 RFC 2308，从 Authority（Ns）优先取 SOA（多数实现都只放在 Authority）
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var soa *dns.SOA
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for _, rr := range m.Ns {
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if s, ok := rr.(*dns.SOA); ok {
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soa = s
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break
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}
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}
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// 兼容性：偶尔也有人把 SOA 放 Extra（不规范，但为了兼容可以兜底看看）
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if soa == nil {
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for _, rr := range m.Extra {
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if s, ok := rr.(*dns.SOA); ok {
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soa = s
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break
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}
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}
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}
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if soa == nil {
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// 建议：无 SOA 时不做负面缓存（返回 0,false）
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return 0, false
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}
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// 负面 TTL 取 min(SOA.MINIMUM, SOA 自身 TTL)，再与配置上限比较
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ttl := soa.Hdr.Ttl
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if soa.Minttl < ttl {
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ttl = soa.Minttl
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}
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capTTL := uint32(maxTTL.Seconds())
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if capTTL > 0 && ttl > capTTL {
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ttl = capTTL
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}
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return ttl, ttl > 0
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}
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func minRRsetTTL(m *dns.Msg) (uint32, bool) {
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minTTL := uint32(0)
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hasTTL := false
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// 优先 Answer -> Ns；若都为空，再考虑 Extra（排除伪记录）
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for _, sec := range [][]dns.RR{m.Answer, m.Ns} {
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for _, rr := range sec {
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if isPseudo(rr) {
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continue
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}
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ttl := rr.Header().Ttl
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if !hasTTL || ttl < minTTL {
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minTTL = ttl
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hasTTL = true
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}
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}
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}
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if !hasTTL {
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for _, rr := range m.Extra {
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if isPseudo(rr) {
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continue
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}
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ttl := rr.Header().Ttl
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if !hasTTL || ttl < minTTL {
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minTTL = ttl
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hasTTL = true
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}
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}
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}
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return minTTL, hasTTL
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}
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func stripPseudoExtras(m *dns.Msg) {
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if len(m.Extra) == 0 {
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return
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}
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out := m.Extra[:0]
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for _, rr := range m.Extra {
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if isPseudo(rr) {
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continue
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}
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out = append(out, rr)
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}
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m.Extra = out
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}
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// 写缓存（保存 EDNS 元数据，命中时可重建扩展 RCODE/EDE）
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func cacheWrite(key string, in *dns.Msg, maxTTL time.Duration) {
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if in == nil {
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return
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}
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if in.Rcode != dns.RcodeSuccess && in.Rcode != dns.RcodeNameError {
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return
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}
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var ttl uint32
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var ok bool
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if ttl, ok = negativeTTL(in, maxTTL); !ok {
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minTTL, has := minRRsetTTL(in)
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if has {
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cfgTTL := uint32(maxTTL.Seconds())
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if cfgTTL > 0 && minTTL > cfgTTL {
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minTTL = cfgTTL
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}
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ttl = minTTL
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} else {
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ttl = uint32(maxTTL.Seconds())
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}
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}
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if ttl == 0 {
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return
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}
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expire := time.Now().Add(time.Duration(ttl) * time.Second)
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cp := in.Copy()
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// 提取 EDNS 元数据后再剥离伪记录
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present, ver, ext, ede := extractEDNSMeta(cp)
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stripPseudoExtras(cp)
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cacheMutex.Lock()
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cache.Add(key, &cacheEntry{
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msg: cp,
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expireAt: expire,
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ednsPresent: present,
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ednsVersion: ver,
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ednsExtRcode: ext,
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ednsEDE: ede,
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})
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cacheMutex.Unlock()
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}
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/******************************************************************
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* 上游查询
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******************************************************************/
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var udpClient *dns.Client
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func shuffled(xs []string) []string {
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out := make([]string, len(xs))
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copy(out, xs)
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rand.Shuffle(len(out), func(i, j int) { out[i], out[j] = out[j], out[i] })
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return out
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}
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// clampEDNSForUpstream 返回一个 msg 副本，把 EDNS UDP size 夹到给定大小
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func clampEDNSForUpstream(in *dns.Msg, size uint16) *dns.Msg {
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m := in.Copy()
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o := m.IsEdns0()
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if o == nil {
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o = &dns.OPT{}
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o.Hdr.Name = "."
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o.Hdr.Rrtype = dns.TypeOPT
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m.Extra = append(m.Extra, o)
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}
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if size > 0 {
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o.SetUDPSize(size)
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}
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return m
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}
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func queryUpstreamsLimited(
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ctx context.Context,
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req *dns.Msg,
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upstreams []string,
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timeout time.Duration,
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maxParallel int,
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allowTCPFallback bool,
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) *dns.Msg {
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if maxParallel <= 0 {
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maxParallel = 1
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}
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servers := shuffled(upstreams)
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cctx, cancel := context.WithTimeout(ctx, timeout)
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defer cancel()
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type result struct{ msg *dns.Msg }
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ch := make(chan result, len(servers))
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sem := make(chan struct{}, maxParallel)
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execOne := func(svr string) {
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upReq := clampEDNSForUpstream(req, 1232) // 或做成 flag
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resp, _, err := udpClient.ExchangeContext(cctx, upReq, svr)
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if err == nil && resp != nil && resp.Truncated && allowTCPFallback {
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log.Printf("[upstream] UDP truncated, retry TCP: %s", svr)
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tcpClient := *udpClient
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tcpClient.Net = "tcp"
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resp, _, err = tcpClient.ExchangeContext(cctx, req.Copy(), svr)
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}
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if err != nil || resp == nil {
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if err != nil && cctx.Err() == nil {
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log.Printf("[upstream] %s error: %v", svr, err)
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}
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return
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}
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if resp.Rcode == dns.RcodeServerFailure || resp.Rcode == dns.RcodeRefused || resp.Rcode == dns.RcodeFormatError {
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return
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}
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select {
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case ch <- result{msg: resp}:
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case <-cctx.Done():
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}
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}
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for _, s := range servers {
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s := s
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go func() {
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select {
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case sem <- struct{}{}:
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defer func() { <-sem }()
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case <-cctx.Done():
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return
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}
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execOne(s)
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}()
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}
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for i := 0; i < len(servers); i++ {
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select {
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case r := <-ch:
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if r.msg != nil {
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cancel()
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return r.msg
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}
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case <-cctx.Done():
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log.Printf("[upstream] timeout after %v", timeout)
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return nil
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}
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}
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return nil
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}
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/******************************************************************
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* EDNS / 响应构造
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******************************************************************/
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func stripECS(m *dns.Msg) {
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if o := m.IsEdns0(); o != nil {
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var kept []dns.EDNS0
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for _, e := range o.Option {
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if _, isECS := e.(*dns.EDNS0_SUBNET); !isECS {
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kept = append(kept, e)
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}
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}
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o.Option = kept
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}
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}
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func getDOFlag(m *dns.Msg) bool {
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if o := m.IsEdns0(); o != nil {
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return o.Do()
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}
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return false
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}
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func writeReply(w dns.ResponseWriter, req *dns.Msg, upstream *dns.Msg, meta *cacheEntry) {
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if upstream == nil {
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dns.HandleFailed(w, req)
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return
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}
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out := new(dns.Msg)
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out.SetReply(req)
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out.Authoritative = false
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out.RecursionAvailable = upstream.RecursionAvailable
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out.AuthenticatedData = upstream.AuthenticatedData
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out.CheckingDisabled = req.CheckingDisabled
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out.Rcode = upstream.Rcode
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out.Answer = upstream.Answer
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out.Ns = upstream.Ns
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var extras []dns.RR
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for _, rr := range upstream.Extra {
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if !isPseudo(rr) {
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extras = append(extras, rr)
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}
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}
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if ro := req.IsEdns0(); ro != nil {
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o := new(dns.OPT)
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o.Hdr.Name = "."
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o.Hdr.Rrtype = dns.TypeOPT
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o.SetUDPSize(ro.UDPSize())
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if ro.Do() {
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o.SetDo()
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}
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if uo := upstream.IsEdns0(); uo != nil {
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o.SetExtendedRcode(uint16(uo.ExtendedRcode()))
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o.SetVersion(uint8(uo.Version()))
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for _, opt := range uo.Option {
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if ede, ok := opt.(*dns.EDNS0_EDE); ok {
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o.Option = append(o.Option, ede)
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}
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}
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} else if meta != nil && meta.ednsPresent {
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// Upstream/cached msg has no OPT（例如缓存时被剥离），用缓存元数据重建
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o.SetExtendedRcode(meta.ednsExtRcode)
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o.SetVersion(meta.ednsVersion)
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for _, e := range meta.ednsEDE {
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o.Option = append(o.Option, e)
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}
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}
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extras = append(extras, o)
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}
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out.Extra = extras
|
||
out.Compress = true
|
||
|
||
if err := w.WriteMsg(out); err != nil {
|
||
log.Printf("[write] WriteMsg error: %v", err)
|
||
}
|
||
}
|
||
|
||
/******************************************************************
|
||
* 主处理器
|
||
******************************************************************/
|
||
func handleDNS(
|
||
upstreams []string,
|
||
cacheMaxTTL, timeout time.Duration,
|
||
maxParallel int,
|
||
stripECSBeforeForward bool,
|
||
allowTCPFallback bool,
|
||
bl *suffixMatcher,
|
||
blRcode int,
|
||
) dns.HandlerFunc {
|
||
return func(w dns.ResponseWriter, r *dns.Msg) {
|
||
if len(r.Question) == 0 {
|
||
dns.HandleFailed(w, r)
|
||
return
|
||
}
|
||
q := r.Question[0]
|
||
log.Printf("[req] %s %s (id=%d cd=%v do=%v from=%s)",
|
||
dns.TypeToString[q.Qtype], q.Name, r.Id, r.CheckingDisabled, getDOFlag(r), w.RemoteAddr())
|
||
|
||
if stripECSBeforeForward {
|
||
stripECS(r)
|
||
}
|
||
|
||
// 黑名单拦截：命中则不查上游，直接返回
|
||
if rule, ok := bl.match(q.Name); ok {
|
||
nameCanon := dns.CanonicalName(q.Name)
|
||
log.Printf("[blacklist] HIT %s rule=%s (no upstream query)", nameCanon, rule)
|
||
up := makeBlockedUpstream(blRcode, rule)
|
||
writeReply(w, r, up, nil)
|
||
return
|
||
}
|
||
|
||
key := cacheKeyFromMsg(q, getDOFlag(r), r.CheckingDisabled)
|
||
|
||
if cachedMsg, cachedMeta, ok := tryCacheRead(key); ok {
|
||
log.Printf("[cache] HIT %s %s", dns.TypeToString[q.Qtype], q.Name)
|
||
writeReply(w, r, cachedMsg, cachedMeta)
|
||
return
|
||
}
|
||
log.Printf("[cache] MISS %s %s", dns.TypeToString[q.Qtype], q.Name)
|
||
|
||
ctx := context.Background()
|
||
resp := queryUpstreamsLimited(ctx, r, upstreams, timeout, maxParallel, allowTCPFallback)
|
||
if resp == nil {
|
||
log.Printf("[error] all upstreams failed for %s", q.Name)
|
||
dns.HandleFailed(w, r)
|
||
return
|
||
}
|
||
cacheWrite(key, resp, cacheMaxTTL)
|
||
for _, ans := range resp.Answer {
|
||
log.Printf("[answer] %s", ans.String())
|
||
}
|
||
writeReply(w, r, resp, nil)
|
||
}
|
||
}
|
||
|
||
/******************************************************************
|
||
* 主函数
|
||
******************************************************************/
|
||
func main() {
|
||
rand.Seed(time.Now().UnixNano())
|
||
|
||
certFile := flag.String("cert", "server.crt", "TLS 证书文件路径")
|
||
keyFile := flag.String("key", "server.key", "TLS 私钥文件路径")
|
||
addr := flag.String("addr", ":853", "DoT 监听地址")
|
||
upstreamStr := flag.String("upstream", "8.8.8.8:53,1.1.1.1:53", "上游 DNS 列表")
|
||
cacheTTLFlag := flag.Duration("cache-ttl", 60*time.Second, "最大缓存 TTL")
|
||
cacheSizeFlag := flag.Int("cache-size", defaultCacheSize, "LRU 缓存大小上限")
|
||
timeoutFlag := flag.Duration("timeout", 3*time.Second, "上游查询超时")
|
||
maxParallel := flag.Int("max-parallel", 3, "并发上游数量")
|
||
stripECSFlag := flag.Bool("strip-ecs", true, "去除 ECS")
|
||
allowTCPFallback := flag.Bool("tcp-fallback", true, "UDP 截断时 TCP 回退")
|
||
blacklistStr := flag.String("blacklist", "", "逗号分隔的黑名单域名（后缀匹配；支持如 *.example.com）")
|
||
blacklistFile := flag.String("blacklist-file", "", "黑名单文件路径（每行一个域名；支持 # 或 ; 注释；后缀匹配）")
|
||
blacklistRcodeFlag := flag.String("blacklist-rcode", "REFUSED", "命中黑名单返回的 RCODE：REFUSED|NXDOMAIN|SERVFAIL")
|
||
verbose := flag.Bool("v", false, "verbose 日志")
|
||
flag.Parse()
|
||
|
||
initLogger(*verbose)
|
||
|
||
var err error
|
||
cache, err = lru.New[string, *cacheEntry](*cacheSizeFlag)
|
||
if err != nil {
|
||
log.Fatalf("[fatal] failed to init LRU cache: %v", err)
|
||
}
|
||
|
||
cert, err := tls.LoadX509KeyPair(*certFile, *keyFile)
|
||
if err != nil {
|
||
log.Fatalf("[fatal] failed to load cert: %v", err)
|
||
}
|
||
|
||
var upstreams []string
|
||
for _, s := range strings.Split(*upstreamStr, ",") {
|
||
if t := strings.TrimSpace(s); t != "" {
|
||
if !strings.Contains(t, ":") {
|
||
t = fmt.Sprintf("%s:53", t)
|
||
}
|
||
upstreams = append(upstreams, t)
|
||
}
|
||
}
|
||
if len(upstreams) == 0 {
|
||
log.Fatal("[fatal] no upstream DNS servers provided")
|
||
}
|
||
|
||
udpClient = &dns.Client{Net: "udp", UDPSize: 4096, SingleInflight: true}
|
||
|
||
ctx, cancel := context.WithCancel(context.Background())
|
||
defer cancel()
|
||
|
||
startCacheCleaner(ctx)
|
||
|
||
// 加载黑名单规则
|
||
bl, blRcode := initBlacklist(ctx, *blacklistStr, *blacklistFile, *blacklistRcodeFlag)
|
||
|
||
mux := dns.NewServeMux()
|
||
mux.HandleFunc(".", handleDNS(
|
||
upstreams,
|
||
*cacheTTLFlag,
|
||
*timeoutFlag,
|
||
*maxParallel,
|
||
*stripECSFlag,
|
||
*allowTCPFallback,
|
||
bl,
|
||
blRcode,
|
||
))
|
||
|
||
srv := &dns.Server{
|
||
Addr: *addr,
|
||
Net: "tcp-tls",
|
||
TLSConfig: &tls.Config{
|
||
Certificates: []tls.Certificate{cert},
|
||
MinVersion: tls.VersionTLS12,
|
||
NextProtos: []string{"dot"},
|
||
},
|
||
Handler: mux,
|
||
ReadTimeout: 10 * time.Second,
|
||
WriteTimeout: 10 * time.Second,
|
||
}
|
||
|
||
stop := make(chan os.Signal, 1)
|
||
signal.Notify(stop, syscall.SIGINT, syscall.SIGTERM)
|
||
|
||
errCh := make(chan error, 1)
|
||
go func() {
|
||
log.Printf("🚀 starting DNS-over-TLS on %s", *addr)
|
||
log.Printf(" upstreams=%v | cache_max_ttl=%s | cache_size=%d | timeout=%s | max_parallel=%d | strip_ecs=%v | tcp_fallback=%v | blacklist_rules=%d | blacklist_rcode=%s",
|
||
upstreams, cacheTTLFlag.String(), *cacheSizeFlag, timeoutFlag.String(), *maxParallel, *stripECSFlag, *allowTCPFallback, len(bl.rules), strings.ToUpper(*blacklistRcodeFlag))
|
||
errCh <- srv.ListenAndServe()
|
||
}()
|
||
|
||
select {
|
||
case sig := <-stop:
|
||
log.Printf("[shutdown] caught signal: %s", sig)
|
||
cancel()
|
||
if err := srv.Shutdown(); err != nil {
|
||
log.Printf("[shutdown] server shutdown error: %v", err)
|
||
}
|
||
case err := <-errCh:
|
||
if err != nil {
|
||
log.Fatalf("[fatal] server error: %v", err)
|
||
}
|
||
}
|
||
|
||
log.Println("[bye] server stopped.")
|
||
}
|