package route import ( "context" "net/netip" "strings" "time" "github.com/sagernet/sing-box/adapter" C "github.com/sagernet/sing-box/constant" "github.com/sagernet/sing-box/log" "github.com/sagernet/sing-dns" "github.com/sagernet/sing/common/cache" E "github.com/sagernet/sing/common/exceptions" F "github.com/sagernet/sing/common/format" M "github.com/sagernet/sing/common/metadata" mDNS "github.com/miekg/dns" ) type DNSReverseMapping struct { cache *cache.LruCache[netip.Addr, string] } func NewDNSReverseMapping() *DNSReverseMapping { return &DNSReverseMapping{ cache: cache.New[netip.Addr, string](), } } func (m *DNSReverseMapping) Save(address netip.Addr, domain string, ttl int) { m.cache.StoreWithExpire(address, domain, time.Now().Add(time.Duration(ttl)*time.Second)) } func (m *DNSReverseMapping) Query(address netip.Addr) (string, bool) { domain, loaded := m.cache.Load(address) return domain, loaded } func (r *Router) matchDNS(ctx context.Context) (context.Context, dns.Transport, dns.DomainStrategy) { metadata := adapter.ContextFrom(ctx) if metadata == nil { panic("no context") } for i, rule := range r.dnsRules { if rule.Match(metadata) { detour := rule.Outbound() transport, loaded := r.transportMap[detour] if !loaded { r.dnsLogger.ErrorContext(ctx, "transport not found: ", detour) continue } if _, isFakeIP := transport.(adapter.FakeIPTransport); isFakeIP && metadata.FakeIP { continue } r.dnsLogger.DebugContext(ctx, "match[", i, "] ", rule.String(), " => ", detour) if rule.DisableCache() { ctx = dns.ContextWithDisableCache(ctx, true) } if rewriteTTL := rule.RewriteTTL(); rewriteTTL != nil { ctx = dns.ContextWithRewriteTTL(ctx, *rewriteTTL) } if domainStrategy, dsLoaded := r.transportDomainStrategy[transport]; dsLoaded { return ctx, transport, domainStrategy } else { return ctx, transport, r.defaultDomainStrategy } } } if domainStrategy, dsLoaded := r.transportDomainStrategy[r.defaultTransport]; dsLoaded { return ctx, r.defaultTransport, domainStrategy } else { return ctx, r.defaultTransport, r.defaultDomainStrategy } } func (r *Router) Exchange(ctx context.Context, message *mDNS.Msg) (*mDNS.Msg, error) { if len(message.Question) > 0 { r.dnsLogger.DebugContext(ctx, "exchange ", formatQuestion(message.Question[0].String())) } var ( response *mDNS.Msg cached bool err error ) response, cached = r.dnsClient.ExchangeCache(ctx, message) if !cached { ctx, metadata := adapter.AppendContext(ctx) if len(message.Question) > 0 { metadata.QueryType = message.Question[0].Qtype switch metadata.QueryType { case mDNS.TypeA: metadata.IPVersion = 4 case mDNS.TypeAAAA: metadata.IPVersion = 6 } metadata.Domain = fqdnToDomain(message.Question[0].Name) } ctx, transport, strategy := r.matchDNS(ctx) ctx, cancel := context.WithTimeout(ctx, C.DNSTimeout) defer cancel() response, err = r.dnsClient.Exchange(ctx, transport, message, strategy) if err != nil && len(message.Question) > 0 { r.dnsLogger.ErrorContext(ctx, E.Cause(err, "exchange failed for ", formatQuestion(message.Question[0].String()))) } } if len(message.Question) > 0 && response != nil { LogDNSAnswers(r.dnsLogger, ctx, message.Question[0].Name, response.Answer) } if r.dnsReverseMapping != nil && len(message.Question) > 0 && response != nil && len(response.Answer) > 0 { for _, answer := range response.Answer { switch record := answer.(type) { case *mDNS.A: r.dnsReverseMapping.Save(M.AddrFromIP(record.A), fqdnToDomain(record.Hdr.Name), int(record.Hdr.Ttl)) case *mDNS.AAAA: r.dnsReverseMapping.Save(M.AddrFromIP(record.AAAA), fqdnToDomain(record.Hdr.Name), int(record.Hdr.Ttl)) } } } return response, err } func (r *Router) Lookup(ctx context.Context, domain string, strategy dns.DomainStrategy) ([]netip.Addr, error) { r.dnsLogger.DebugContext(ctx, "lookup domain ", domain) ctx, metadata := adapter.AppendContext(ctx) metadata.Domain = domain ctx, transport, transportStrategy := r.matchDNS(ctx) if strategy == dns.DomainStrategyAsIS { strategy = transportStrategy } ctx, cancel := context.WithTimeout(ctx, C.DNSTimeout) defer cancel() addrs, err := r.dnsClient.Lookup(ctx, transport, domain, strategy) if len(addrs) > 0 { r.dnsLogger.InfoContext(ctx, "lookup succeed for ", domain, ": ", strings.Join(F.MapToString(addrs), " ")) } else if err != nil { r.dnsLogger.ErrorContext(ctx, E.Cause(err, "lookup failed for ", domain)) } else { r.dnsLogger.ErrorContext(ctx, "lookup failed for ", domain, ": empty result") err = dns.RCodeNameError } return addrs, err } func (r *Router) LookupDefault(ctx context.Context, domain string) ([]netip.Addr, error) { return r.Lookup(ctx, domain, dns.DomainStrategyAsIS) } func (r *Router) ClearDNSCache() { r.dnsClient.ClearCache() if r.platformInterface != nil { r.platformInterface.ClearDNSCache() } } func LogDNSAnswers(logger log.ContextLogger, ctx context.Context, domain string, answers []mDNS.RR) { for _, answer := range answers { logger.InfoContext(ctx, "exchanged ", domain, " ", mDNS.Type(answer.Header().Rrtype).String(), " ", formatQuestion(answer.String())) } } func fqdnToDomain(fqdn string) string { if mDNS.IsFqdn(fqdn) { return fqdn[:len(fqdn)-1] } return fqdn } func formatQuestion(string string) string { if strings.HasPrefix(string, ";") { string = string[1:] } string = strings.ReplaceAll(string, "\t", " ") for strings.Contains(string, " ") { string = strings.ReplaceAll(string, " ", " ") } return string }