321 lines
8.1 KiB
Go
321 lines
8.1 KiB
Go
package dns
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import (
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"context"
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"crypto/tls"
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"errors"
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"fmt"
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"net"
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"net/netip"
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"strings"
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"time"
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"github.com/Dreamacro/clash/common/cache"
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N "github.com/Dreamacro/clash/common/net"
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"github.com/Dreamacro/clash/common/nnip"
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"github.com/Dreamacro/clash/common/picker"
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"github.com/Dreamacro/clash/component/dialer"
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"github.com/Dreamacro/clash/component/resolver"
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C "github.com/Dreamacro/clash/constant"
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"github.com/Dreamacro/clash/log"
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"github.com/Dreamacro/clash/tunnel"
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D "github.com/miekg/dns"
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"github.com/samber/lo"
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)
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const (
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MaxMsgSize = 65535
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)
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func minimalTTL(records []D.RR) uint32 {
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return lo.MinBy(records, func(r1 D.RR, r2 D.RR) bool {
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return r1.Header().Ttl < r2.Header().Ttl
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}).Header().Ttl
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}
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func updateTTL(records []D.RR, ttl uint32) {
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if len(records) == 0 {
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return
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}
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delta := minimalTTL(records) - ttl
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for i := range records {
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records[i].Header().Ttl = lo.Clamp(records[i].Header().Ttl-delta, 1, records[i].Header().Ttl)
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}
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}
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func putMsgToCache(c *cache.LruCache[string, *D.Msg], key string, msg *D.Msg) {
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// skip dns cache for acme challenge
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if len(msg.Question) != 0 {
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if q := msg.Question[0]; q.Qtype == D.TypeTXT && strings.HasPrefix(q.Name, "_acme-challenge") {
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log.Debugln("[DNS] dns cache ignored because of acme challenge for: %s", q.Name)
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return
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}
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}
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var ttl uint32
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switch {
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case len(msg.Answer) != 0:
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ttl = minimalTTL(msg.Answer)
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case len(msg.Ns) != 0:
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ttl = minimalTTL(msg.Ns)
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case len(msg.Extra) != 0:
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ttl = minimalTTL(msg.Extra)
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default:
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log.Debugln("[DNS] response msg empty: %#v", msg)
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return
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}
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c.SetWithExpire(key, msg.Copy(), time.Now().Add(time.Second*time.Duration(ttl)))
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}
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func setMsgTTL(msg *D.Msg, ttl uint32) {
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for _, answer := range msg.Answer {
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answer.Header().Ttl = ttl
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}
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for _, ns := range msg.Ns {
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ns.Header().Ttl = ttl
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}
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for _, extra := range msg.Extra {
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extra.Header().Ttl = ttl
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}
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}
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func updateMsgTTL(msg *D.Msg, ttl uint32) {
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updateTTL(msg.Answer, ttl)
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updateTTL(msg.Ns, ttl)
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updateTTL(msg.Extra, ttl)
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}
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func isIPRequest(q D.Question) bool {
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return q.Qclass == D.ClassINET && (q.Qtype == D.TypeA || q.Qtype == D.TypeAAAA || q.Qtype == D.TypeCNAME)
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}
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func transform(servers []NameServer, resolver *Resolver) []dnsClient {
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ret := make([]dnsClient, 0, len(servers))
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for _, s := range servers {
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switch s.Net {
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case "https":
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ret = append(ret, newDoHClient(s.Addr, resolver, s.PreferH3, s.Params, s.ProxyAdapter, s.ProxyName))
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continue
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case "dhcp":
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ret = append(ret, newDHCPClient(s.Addr))
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continue
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case "system":
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clients, err := loadSystemResolver()
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if err != nil {
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log.Errorln("[DNS:system] load system resolver failed: %s", err.Error())
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continue
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}
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if len(clients) == 0 {
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log.Errorln("[DNS:system] no nameserver found in system")
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continue
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}
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ret = append(ret, clients...)
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continue
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case "rcode":
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ret = append(ret, newRCodeClient(s.Addr))
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continue
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case "quic":
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if doq, err := newDoQ(resolver, s.Addr, s.ProxyAdapter, s.ProxyName); err == nil {
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ret = append(ret, doq)
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} else {
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log.Fatalln("DoQ format error: %v", err)
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}
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continue
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}
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host, port, _ := net.SplitHostPort(s.Addr)
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ret = append(ret, &client{
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Client: &D.Client{
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Net: s.Net,
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TLSConfig: &tls.Config{
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ServerName: host,
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},
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UDPSize: 4096,
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Timeout: 5 * time.Second,
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},
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port: port,
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host: host,
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iface: s.Interface,
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r: resolver,
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proxyAdapter: s.ProxyAdapter,
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proxyName: s.ProxyName,
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})
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}
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return ret
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}
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func handleMsgWithEmptyAnswer(r *D.Msg) *D.Msg {
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msg := &D.Msg{}
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msg.Answer = []D.RR{}
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msg.SetRcode(r, D.RcodeSuccess)
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msg.Authoritative = true
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msg.RecursionAvailable = true
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return msg
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}
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func msgToIP(msg *D.Msg) []netip.Addr {
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ips := []netip.Addr{}
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for _, answer := range msg.Answer {
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switch ans := answer.(type) {
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case *D.AAAA:
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ips = append(ips, nnip.IpToAddr(ans.AAAA))
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case *D.A:
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ips = append(ips, nnip.IpToAddr(ans.A))
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}
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}
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return ips
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}
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func msgToDomain(msg *D.Msg) string {
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if len(msg.Question) > 0 {
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return strings.TrimRight(msg.Question[0].Name, ".")
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}
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return ""
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}
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type dialHandler func(ctx context.Context, network, addr string) (net.Conn, error)
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func getDialHandler(r *Resolver, proxyAdapter C.ProxyAdapter, proxyName string, opts ...dialer.Option) dialHandler {
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return func(ctx context.Context, network, addr string) (net.Conn, error) {
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if len(proxyName) == 0 && proxyAdapter == nil {
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opts = append(opts, dialer.WithResolver(r))
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return dialer.DialContext(ctx, network, addr, opts...)
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} else {
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host, port, err := net.SplitHostPort(addr)
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if err != nil {
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return nil, err
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}
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if proxyAdapter == nil {
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var ok bool
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proxyAdapter, ok = tunnel.Proxies()[proxyName]
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if !ok {
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opts = append(opts, dialer.WithInterface(proxyName))
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}
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}
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if strings.Contains(network, "tcp") {
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// tcp can resolve host by remote
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metadata := &C.Metadata{
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NetWork: C.TCP,
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Host: host,
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DstPort: port,
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}
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if proxyAdapter != nil {
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if proxyAdapter.IsL3Protocol(metadata) { // L3 proxy should resolve domain before to avoid loopback
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dstIP, err := resolver.ResolveIPWithResolver(ctx, host, r)
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if err != nil {
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return nil, err
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}
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metadata.Host = ""
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metadata.DstIP = dstIP
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}
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return proxyAdapter.DialContext(ctx, metadata, opts...)
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}
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opts = append(opts, dialer.WithResolver(r))
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return dialer.DialContext(ctx, network, addr, opts...)
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} else {
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// udp must resolve host first
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dstIP, err := resolver.ResolveIPWithResolver(ctx, host, r)
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if err != nil {
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return nil, err
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}
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metadata := &C.Metadata{
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NetWork: C.UDP,
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Host: "",
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DstIP: dstIP,
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DstPort: port,
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}
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if proxyAdapter == nil {
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return dialer.DialContext(ctx, network, addr, opts...)
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}
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if !proxyAdapter.SupportUDP() {
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return nil, fmt.Errorf("proxy adapter [%s] UDP is not supported", proxyAdapter)
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}
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packetConn, err := proxyAdapter.ListenPacketContext(ctx, metadata, opts...)
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if err != nil {
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return nil, err
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}
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return N.NewBindPacketConn(packetConn, metadata.UDPAddr()), nil
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}
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}
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}
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}
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func listenPacket(ctx context.Context, proxyAdapter C.ProxyAdapter, proxyName string, network string, addr string, r *Resolver, opts ...dialer.Option) (net.PacketConn, error) {
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host, port, err := net.SplitHostPort(addr)
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if err != nil {
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return nil, err
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}
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if proxyAdapter == nil {
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var ok bool
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proxyAdapter, ok = tunnel.Proxies()[proxyName]
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if !ok {
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opts = append(opts, dialer.WithInterface(proxyName))
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}
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}
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// udp must resolve host first
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dstIP, err := resolver.ResolveIPWithResolver(ctx, host, r)
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if err != nil {
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return nil, err
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}
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metadata := &C.Metadata{
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NetWork: C.UDP,
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Host: "",
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DstIP: dstIP,
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DstPort: port,
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}
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if proxyAdapter == nil {
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return dialer.ListenPacket(ctx, dialer.ParseNetwork(network, dstIP), "", opts...)
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}
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if !proxyAdapter.SupportUDP() {
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return nil, fmt.Errorf("proxy adapter [%s] UDP is not supported", proxyAdapter)
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}
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return proxyAdapter.ListenPacketContext(ctx, metadata, opts...)
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}
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func batchExchange(ctx context.Context, clients []dnsClient, m *D.Msg) (msg *D.Msg, cache bool, err error) {
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fast, ctx := picker.WithTimeout[*D.Msg](ctx, resolver.DefaultDNSTimeout)
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domain := msgToDomain(m)
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for _, client := range clients {
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_, cache = client.(rcodeClient)
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cache = !cache
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fast.Go(func() (*D.Msg, error) {
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log.Debugln("[DNS] resolve %s from %s", domain, client.Address())
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m, err := client.ExchangeContext(ctx, m)
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if err != nil {
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return nil, err
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} else if cache && (m.Rcode == D.RcodeServerFailure || m.Rcode == D.RcodeRefused) {
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// currently, cache indicates whether this msg was from a RCode client,
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// so we would ignore RCode errors from RCode clients.
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return nil, errors.New("server failure")
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}
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log.Debugln("[DNS] %s --> %s, from %s", domain, msgToIP(m), client.Address())
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return m, nil
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})
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}
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elm := fast.Wait()
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if elm == nil {
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err := errors.New("all DNS requests failed")
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if fErr := fast.Error(); fErr != nil {
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err = fmt.Errorf("%w, first error: %s", err, fErr.Error())
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}
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return nil, true, err
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}
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msg = elm
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return
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}
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