package app import ( "fmt" "math/rand" "net" "net/url" "time" "git.zio.sh/astra/doggo/pkg/config" "git.zio.sh/astra/doggo/pkg/models" "github.com/ameshkov/dnsstamps" ) // LoadNameservers reads all the user given // nameservers and loads to App. func (app *App) LoadNameservers() error { for _, srv := range app.QueryFlags.Nameservers { ns, err := initNameserver(srv) if err != nil { return fmt.Errorf("error parsing nameserver: %s", srv) } // check if properly initialised. if ns.Address != "" && ns.Type != "" { app.Nameservers = append(app.Nameservers, ns) } } // Set `ndots` to the user specified value. app.ResolverOpts.Ndots = app.QueryFlags.Ndots // fallback to system nameserver // in case no nameserver is specified by user. if len(app.Nameservers) == 0 { ns, ndots, search, err := getDefaultServers(app.QueryFlags.Strategy) if err != nil { return fmt.Errorf("error fetching system default nameserver") } // `-1` indicates the flag is not set. // use from config if user hasn't specified any value. if app.ResolverOpts.Ndots == -1 { app.ResolverOpts.Ndots = ndots } if len(search) > 0 && app.QueryFlags.UseSearchList { app.ResolverOpts.SearchList = search } app.Nameservers = append(app.Nameservers, ns...) } // if the user hasn't given any override of `ndots` AND has // given a custom nameserver. Set `ndots` to 1 as the fallback value if app.ResolverOpts.Ndots == -1 { app.ResolverOpts.Ndots = 0 } return nil } func initNameserver(n string) (models.Nameserver, error) { // Instantiate a UDP resolver with default port as a fallback. ns := models.Nameserver{ Type: models.UDPResolver, Address: net.JoinHostPort(n, models.DefaultUDPPort), } u, err := url.Parse(n) if err != nil { ip := net.ParseIP(n) if ip == nil { return ns, err } return ns, nil } switch u.Scheme { case "sdns": stamp, err := dnsstamps.NewServerStampFromString(n) if err != nil { return ns, err } switch stamp.Proto { case dnsstamps.StampProtoTypeDoH: ns.Type = models.DOHResolver address := url.URL{Scheme: "https", Host: stamp.ProviderName, Path: stamp.Path} ns.Address = address.String() case dnsstamps.StampProtoTypeDNSCrypt: ns.Type = models.DNSCryptResolver ns.Address = n default: return ns, fmt.Errorf("unsupported protocol: %v", stamp.Proto.String()) } case "https": ns.Type = models.DOHResolver ns.Address = u.String() case "tls": ns.Type = models.DOTResolver if u.Port() == "" { ns.Address = net.JoinHostPort(u.Hostname(), models.DefaultTLSPort) } else { ns.Address = net.JoinHostPort(u.Hostname(), u.Port()) } case "tcp": ns.Type = models.TCPResolver if u.Port() == "" { ns.Address = net.JoinHostPort(u.Hostname(), models.DefaultTCPPort) } else { ns.Address = net.JoinHostPort(u.Hostname(), u.Port()) } case "udp": ns.Type = models.UDPResolver if u.Port() == "" { ns.Address = net.JoinHostPort(u.Hostname(), models.DefaultUDPPort) } else { ns.Address = net.JoinHostPort(u.Hostname(), u.Port()) } case "quic": ns.Type = models.DOQResolver if u.Port() == "" { ns.Address = net.JoinHostPort(u.Hostname(), models.DefaultDOQPort) } else { ns.Address = net.JoinHostPort(u.Hostname(), u.Port()) } } return ns, nil } func getDefaultServers(strategy string) ([]models.Nameserver, int, []string, error) { // Load nameservers from `/etc/resolv.conf`. dnsServers, ndots, search, err := config.GetDefaultServers() if err != nil { return nil, 0, nil, err } servers := make([]models.Nameserver, 0, len(dnsServers)) switch strategy { case "random": // Choose a random server from the list. rand.Seed(time.Now().Unix()) srv := dnsServers[rand.Intn(len(dnsServers))] ns := models.Nameserver{ Type: models.UDPResolver, Address: net.JoinHostPort(srv, models.DefaultUDPPort), } servers = append(servers, ns) case "first": // Choose the first from the list, always. srv := dnsServers[0] ns := models.Nameserver{ Type: models.UDPResolver, Address: net.JoinHostPort(srv, models.DefaultUDPPort), } servers = append(servers, ns) default: // Default behaviour is to load all nameservers. for _, s := range dnsServers { ns := models.Nameserver{ Type: models.UDPResolver, Address: net.JoinHostPort(s, models.DefaultUDPPort), } servers = append(servers, ns) } } return servers, ndots, search, nil }