refactor: DNS

dns/transport_dialer.go

@@ -0,0 +1,93 @@
+package dns
+
+import (
+	"context"
+	"net"
+	"time"
+
+	"github.com/sagernet/sing-box/adapter"
+	"github.com/sagernet/sing-box/common/dialer"
+	C "github.com/sagernet/sing-box/constant"
+	"github.com/sagernet/sing-box/option"
+	E "github.com/sagernet/sing/common/exceptions"
+	M "github.com/sagernet/sing/common/metadata"
+	N "github.com/sagernet/sing/common/network"
+	"github.com/sagernet/sing/service"
+)
+
+func NewLocalDialer(ctx context.Context, options option.LocalDNSServerOptions) (N.Dialer, error) {
+	if options.LegacyDefaultDialer {
+		return dialer.NewDefaultOutbound(ctx), nil
+	} else {
+		return dialer.New(ctx, options.DialerOptions)
+	}
+}
+
+func NewRemoteDialer(ctx context.Context, options option.RemoteDNSServerOptions) (N.Dialer, error) {
+	transportDialer, err := NewLocalDialer(ctx, options.LocalDNSServerOptions)
+	if err != nil {
+		return nil, err
+	}
+	if options.AddressResolver != "" {
+		transport := service.FromContext[adapter.DNSTransportManager](ctx)
+		resolverTransport, loaded := transport.Transport(options.AddressResolver)
+		if !loaded {
+			return nil, E.New("address resolver not found: ", options.AddressResolver)
+		}
+		transportDialer = NewTransportDialer(transportDialer, service.FromContext[adapter.DNSRouter](ctx), resolverTransport, C.DomainStrategy(options.AddressStrategy), time.Duration(options.AddressFallbackDelay))
+	} else if M.IsDomainName(options.Server) {
+		return nil, E.New("missing address resolver for server: ", options.Server)
+	}
+	return transportDialer, nil
+}
+
+type TransportDialer struct {
+	dialer        N.Dialer
+	dnsRouter     adapter.DNSRouter
+	transport     adapter.DNSTransport
+	strategy      C.DomainStrategy
+	fallbackDelay time.Duration
+}
+
+func NewTransportDialer(dialer N.Dialer, dnsRouter adapter.DNSRouter, transport adapter.DNSTransport, strategy C.DomainStrategy, fallbackDelay time.Duration) *TransportDialer {
+	return &TransportDialer{
+		dialer,
+		dnsRouter,
+		transport,
+		strategy,
+		fallbackDelay,
+	}
+}
+
+func (d *TransportDialer) DialContext(ctx context.Context, network string, destination M.Socksaddr) (net.Conn, error) {
+	if destination.IsIP() {
+		return d.dialer.DialContext(ctx, network, destination)
+	}
+	addresses, err := d.dnsRouter.Lookup(ctx, destination.Fqdn, adapter.DNSQueryOptions{
+		Transport: d.transport,
+		Strategy:  d.strategy,
+	})
+	if err != nil {
+		return nil, err
+	}
+	return N.DialParallel(ctx, d.dialer, network, destination, addresses, d.strategy == C.DomainStrategyPreferIPv6, d.fallbackDelay)
+}
+
+func (d *TransportDialer) ListenPacket(ctx context.Context, destination M.Socksaddr) (net.PacketConn, error) {
+	if destination.IsIP() {
+		return d.dialer.ListenPacket(ctx, destination)
+	}
+	addresses, err := d.dnsRouter.Lookup(ctx, destination.Fqdn, adapter.DNSQueryOptions{
+		Transport: d.transport,
+		Strategy:  d.strategy,
+	})
+	if err != nil {
+		return nil, err
+	}
+	conn, _, err := N.ListenSerial(ctx, d.dialer, destination, addresses)
+	return conn, err
+}
+
+func (d *TransportDialer) Upstream() any {
+	return d.dialer
+}