package dns //go:generate go run github.com/xtls/xray-core/common/errors/errorgen import ( "context" "fmt" "log" "net/url" "strings" "sync" "time" "github.com/xtls/xray-core/app/router" "github.com/xtls/xray-core/common" "github.com/xtls/xray-core/common/errors" "github.com/xtls/xray-core/common/net" "github.com/xtls/xray-core/common/session" "github.com/xtls/xray-core/common/strmatcher" "github.com/xtls/xray-core/common/uuid" core "github.com/xtls/xray-core/core" "github.com/xtls/xray-core/features" "github.com/xtls/xray-core/features/dns" "github.com/xtls/xray-core/features/routing" ) // Server is a DNS rely server. type Server struct { sync.Mutex hosts *StaticHosts clientIP net.IP clients []Client // clientIdx -> Client ctx context.Context ipIndexMap []*MultiGeoIPMatcher // clientIdx -> *MultiGeoIPMatcher domainRules [][]string // clientIdx -> domainRuleIdx -> DomainRule domainMatcher strmatcher.IndexMatcher matcherInfos []DomainMatcherInfo // matcherIdx -> DomainMatcherInfo tag string } // DomainMatcherInfo contains information attached to index returned by Server.domainMatcher type DomainMatcherInfo struct { clientIdx uint16 domainRuleIdx uint16 } // MultiGeoIPMatcher for match type MultiGeoIPMatcher struct { matchers []*router.GeoIPMatcher } var errExpectedIPNonMatch = errors.New("expectIPs not match") // Match check ip match func (c *MultiGeoIPMatcher) Match(ip net.IP) bool { for _, matcher := range c.matchers { if matcher.Match(ip) { return true } } return false } // HasMatcher check has matcher func (c *MultiGeoIPMatcher) HasMatcher() bool { return len(c.matchers) > 0 } func generateRandomTag() string { id := uuid.New() return "xray.system." + id.String() } // New creates a new DNS server with given configuration. func New(ctx context.Context, config *Config) (*Server, error) { server := &Server{ clients: make([]Client, 0, len(config.NameServers)+len(config.NameServer)), ctx: ctx, tag: config.Tag, } if server.tag == "" { server.tag = generateRandomTag() } if len(config.ClientIp) > 0 { if len(config.ClientIp) != net.IPv4len && len(config.ClientIp) != net.IPv6len { return nil, newError("unexpected IP length", len(config.ClientIp)) } server.clientIP = net.IP(config.ClientIp) } hosts, err := NewStaticHosts(config.StaticHosts, config.Hosts) if err != nil { return nil, newError("failed to create hosts").Base(err) } server.hosts = hosts addNameServer := func(ns *NameServer) int { endpoint := ns.Address address := endpoint.Address.AsAddress() switch { case address.Family().IsDomain() && address.Domain() == "localhost": server.clients = append(server.clients, NewLocalNameServer()) // Priotize local domains with specific TLDs or without any dot to local DNS // References: // https://www.iana.org/assignments/special-use-domain-names/special-use-domain-names.xhtml // https://unix.stackexchange.com/questions/92441/whats-the-difference-between-local-home-and-lan localTLDsAndDotlessDomains := []*NameServer_PriorityDomain{ {Type: DomainMatchingType_Regex, Domain: "^[^.]+$"}, // This will only match domains without any dot {Type: DomainMatchingType_Subdomain, Domain: "local"}, {Type: DomainMatchingType_Subdomain, Domain: "localdomain"}, {Type: DomainMatchingType_Subdomain, Domain: "localhost"}, {Type: DomainMatchingType_Subdomain, Domain: "lan"}, {Type: DomainMatchingType_Subdomain, Domain: "home.arpa"}, {Type: DomainMatchingType_Subdomain, Domain: "example"}, {Type: DomainMatchingType_Subdomain, Domain: "invalid"}, {Type: DomainMatchingType_Subdomain, Domain: "test"}, } ns.PrioritizedDomain = append(ns.PrioritizedDomain, localTLDsAndDotlessDomains...) case address.Family().IsDomain() && strings.HasPrefix(address.Domain(), "https+local://"): // URI schemed string treated as domain // DOH Local mode u, err := url.Parse(address.Domain()) if err != nil { log.Fatalln(newError("DNS config error").Base(err)) } server.clients = append(server.clients, NewDoHLocalNameServer(u, server.clientIP)) case address.Family().IsDomain() && strings.HasPrefix(address.Domain(), "https://"): // DOH Remote mode u, err := url.Parse(address.Domain()) if err != nil { log.Fatalln(newError("DNS config error").Base(err)) } idx := len(server.clients) server.clients = append(server.clients, nil) // need the core dispatcher, register DOHClient at callback common.Must(core.RequireFeatures(ctx, func(d routing.Dispatcher) { c, err := NewDoHNameServer(u, d, server.clientIP) if err != nil { log.Fatalln(newError("DNS config error").Base(err)) } server.clients[idx] = c })) case address.Family().IsDomain() && address.Domain() == "fakedns": server.clients = append(server.clients, NewFakeDNSServer()) default: // UDP classic DNS mode dest := endpoint.AsDestination() if dest.Network == net.Network_Unknown { dest.Network = net.Network_UDP } if dest.Network == net.Network_UDP { idx := len(server.clients) server.clients = append(server.clients, nil) common.Must(core.RequireFeatures(ctx, func(d routing.Dispatcher) { server.clients[idx] = NewClassicNameServer(dest, d, server.clientIP) })) } } server.ipIndexMap = append(server.ipIndexMap, nil) return len(server.clients) - 1 } if len(config.NameServers) > 0 { features.PrintDeprecatedFeatureWarning("simple DNS server") for _, destPB := range config.NameServers { addNameServer(&NameServer{Address: destPB}) } } if len(config.NameServer) > 0 { clientIndices := []int{} domainRuleCount := 0 for _, ns := range config.NameServer { idx := addNameServer(ns) clientIndices = append(clientIndices, idx) domainRuleCount += len(ns.PrioritizedDomain) } domainRules := make([][]string, len(server.clients)) domainMatcher := &strmatcher.MatcherGroup{} matcherInfos := make([]DomainMatcherInfo, domainRuleCount+1) // matcher index starts from 1 var geoIPMatcherContainer router.GeoIPMatcherContainer for nidx, ns := range config.NameServer { idx := clientIndices[nidx] // Establish domain rule matcher rules := []string{} ruleCurr := 0 ruleIter := 0 for _, domain := range ns.PrioritizedDomain { matcher, err := toStrMatcher(domain.Type, domain.Domain) if err != nil { return nil, newError("failed to create prioritized domain").Base(err).AtWarning() } midx := domainMatcher.Add(matcher) if midx >= uint32(len(matcherInfos)) { // This rarely happens according to current matcher's implementation newError("expanding domain matcher info array to size ", midx, " when adding ", matcher).AtDebug().WriteToLog() matcherInfos = append(matcherInfos, make([]DomainMatcherInfo, midx-uint32(len(matcherInfos))+1)...) } info := &matcherInfos[midx] info.clientIdx = uint16(idx) if ruleCurr < len(ns.OriginalRules) { info.domainRuleIdx = uint16(ruleCurr) rule := ns.OriginalRules[ruleCurr] if ruleCurr >= len(rules) { rules = append(rules, rule.Rule) } ruleIter++ if ruleIter >= int(rule.Size) { ruleIter = 0 ruleCurr++ } } else { // No original rule, generate one according to current domain matcher (majorly for compatibility with tests) info.domainRuleIdx = uint16(len(rules)) rules = append(rules, matcher.String()) } } domainRules[idx] = rules // only add to ipIndexMap if GeoIP is configured if len(ns.Geoip) > 0 { var matchers []*router.GeoIPMatcher for _, geoip := range ns.Geoip { matcher, err := geoIPMatcherContainer.Add(geoip) if err != nil { return nil, newError("failed to create ip matcher").Base(err).AtWarning() } matchers = append(matchers, matcher) } matcher := &MultiGeoIPMatcher{matchers: matchers} server.ipIndexMap[idx] = matcher } } server.domainRules = domainRules server.domainMatcher = domainMatcher server.matcherInfos = matcherInfos } if len(server.clients) == 0 { server.clients = append(server.clients, NewLocalNameServer()) server.ipIndexMap = append(server.ipIndexMap, nil) } return server, nil } // Type implements common.HasType. func (*Server) Type() interface{} { return dns.ClientType() } // Start implements common.Runnable. func (s *Server) Start() error { return nil } // Close implements common.Closable. func (s *Server) Close() error { return nil } func (s *Server) IsOwnLink(ctx context.Context) bool { inbound := session.InboundFromContext(ctx) return inbound != nil && inbound.Tag == s.tag } // Match check dns ip match geoip func (s *Server) Match(idx int, client Client, domain string, ips []net.IP) ([]net.IP, error) { var matcher *MultiGeoIPMatcher if idx < len(s.ipIndexMap) { matcher = s.ipIndexMap[idx] } if matcher == nil { return ips, nil } if !matcher.HasMatcher() { newError("domain ", domain, " server has no valid matcher: ", client.Name(), " idx:", idx).AtDebug().WriteToLog() return ips, nil } newIps := []net.IP{} for _, ip := range ips { if matcher.Match(ip) { newIps = append(newIps, ip) } } if len(newIps) == 0 { return nil, errExpectedIPNonMatch } newError("domain ", domain, " expectIPs ", newIps, " matched at server ", client.Name(), " idx:", idx).AtDebug().WriteToLog() return newIps, nil } func (s *Server) queryIPTimeout(idx int, client Client, domain string, option dns.IPOption) ([]net.IP, error) { ctx, cancel := context.WithTimeout(s.ctx, time.Second*4) if len(s.tag) > 0 { ctx = session.ContextWithInbound(ctx, &session.Inbound{ Tag: s.tag, }) } ips, err := client.QueryIP(ctx, domain, option) cancel() if err != nil { return ips, err } ips, err = s.Match(idx, client, domain, ips) return ips, err } func (s *Server) lookupStatic(domain string, option dns.IPOption, depth int32) []net.Address { ips := s.hosts.LookupIP(domain, option) if ips == nil { return nil } if ips[0].Family().IsDomain() && depth < 5 { if newIPs := s.lookupStatic(ips[0].Domain(), option, depth+1); newIPs != nil { return newIPs } } return ips } func toNetIP(ips []net.Address) []net.IP { if len(ips) == 0 { return nil } netips := make([]net.IP, 0, len(ips)) for _, ip := range ips { netips = append(netips, ip.IP()) } return netips } // LookupIP implements dns.Client. func (s *Server) LookupIP(domain string, option dns.IPOption) ([]net.IP, error) { if domain == "" { return nil, newError("empty domain name") } // normalize the FQDN form query if strings.HasSuffix(domain, ".") { domain = domain[:len(domain)-1] } ips := s.lookupStatic(domain, option, 0) if ips != nil && ips[0].Family().IsIP() { newError("returning ", len(ips), " IPs for domain ", domain).WriteToLog() return toNetIP(ips), nil } if ips != nil && ips[0].Family().IsDomain() { newdomain := ips[0].Domain() newError("domain replaced: ", domain, " -> ", newdomain).WriteToLog() domain = newdomain } var lastErr error var matchedClient Client if s.domainMatcher != nil { indices := s.domainMatcher.Match(domain) domainRules := []string{} matchingDNS := []string{} for _, idx := range indices { info := s.matcherInfos[idx] rule := s.domainRules[info.clientIdx][info.domainRuleIdx] domainRules = append(domainRules, fmt.Sprintf("%s(DNS idx:%d)", rule, info.clientIdx)) matchingDNS = append(matchingDNS, s.clients[info.clientIdx].Name()) } if len(domainRules) > 0 { newError("domain ", domain, " matches following rules: ", domainRules).AtDebug().WriteToLog() } if len(matchingDNS) > 0 { newError("domain ", domain, " uses following DNS first: ", matchingDNS).AtDebug().WriteToLog() } for _, idx := range indices { clientIdx := int(s.matcherInfos[idx].clientIdx) matchedClient = s.clients[clientIdx] if !option.FakeEnable && strings.EqualFold(matchedClient.Name(), "FakeDNS") { newError("skip DNS resolution for domain ", domain, " at server ", matchedClient.Name()).AtDebug().WriteToLog() continue } ips, err := s.queryIPTimeout(clientIdx, matchedClient, domain, option) if len(ips) > 0 { return ips, nil } if err == dns.ErrEmptyResponse { return nil, err } if err != nil { newError("failed to lookup ip for domain ", domain, " at server ", matchedClient.Name()).Base(err).WriteToLog() lastErr = err } } } for idx, client := range s.clients { if client == matchedClient { newError("domain ", domain, " at server ", client.Name(), " idx:", idx, " already lookup failed, just ignore").AtDebug().WriteToLog() continue } if !option.FakeEnable && strings.EqualFold(client.Name(), "FakeDNS") { newError("skip DNS resolution for domain ", domain, " at server ", client.Name()).AtDebug().WriteToLog() continue } ips, err := s.queryIPTimeout(idx, client, domain, option) if len(ips) > 0 { return ips, nil } if err != nil { newError("failed to lookup ip for domain ", domain, " at server ", client.Name()).Base(err).WriteToLog() lastErr = err } if err != context.Canceled && err != context.DeadlineExceeded && err != errExpectedIPNonMatch { return nil, err } } return nil, newError("returning nil for domain ", domain).Base(lastErr) } func init() { common.Must(common.RegisterConfig((*Config)(nil), func(ctx context.Context, config interface{}) (interface{}, error) { return New(ctx, config.(*Config)) })) }