Add resolver for outbound dialer

dns/client_test.go

@@ -0,0 +1,46 @@
+package dns_test
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	M "github.com/sagernet/sing/common/metadata"
+	N "github.com/sagernet/sing/common/network"
+
+	C "github.com/sagernet/sing-box/constant"
+	"github.com/sagernet/sing-box/dns"
+	"github.com/sagernet/sing-box/log"
+	"github.com/sagernet/sing-box/option"
+
+	"github.com/stretchr/testify/require"
+	"golang.org/x/net/dns/dnsmessage"
+)
+
+func TestClient(t *testing.T) {
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
+	client := dns.NewClient(option.DNSClientOptions{})
+	dnsTransport := dns.NewTCPTransport(context.Background(), N.SystemDialer, log.NewNopLogger(), M.ParseSocksaddr("1.0.0.1:53"))
+	response, err := client.Exchange(ctx, dnsTransport, makeQuery())
+	require.NoError(t, err)
+	require.NotEmpty(t, response.Answers, "no answers")
+	response, err = client.Exchange(ctx, dnsTransport, makeQuery())
+	require.NoError(t, err)
+	require.NotEmpty(t, response.Answers, "no answers")
+	addresses, err := client.Lookup(ctx, dnsTransport, "www.google.com", C.DomainStrategyAsIS)
+	require.NoError(t, err)
+	require.NotEmpty(t, addresses, "no answers")
+	cancel()
+}
+
+func makeQuery() *dnsmessage.Message {
+	message := &dnsmessage.Message{}
+	message.Header.ID = 1
+	message.Header.RecursionDesired = true
+	message.Questions = append(message.Questions, dnsmessage.Question{
+		Name:  dnsmessage.MustNewName("google.com."),
+		Type:  dnsmessage.TypeA,
+		Class: dnsmessage.ClassINET,
+	})
+	return message
+}

dns/dialer.go

@@ -0,0 +1,68 @@
+package dns
+
+import (
+	"context"
+	"net"
+
+	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-box/adapter"
+	C "github.com/sagernet/sing-box/constant"
+)
+
+type DialerWrapper struct {
+	dialer    N.Dialer
+	strategy  C.DomainStrategy
+	client    adapter.DNSClient
+	transport adapter.DNSTransport
+}
+
+func NewDialerWrapper(dialer N.Dialer, strategy C.DomainStrategy, client adapter.DNSClient, transport adapter.DNSTransport) N.Dialer {
+	return &DialerWrapper{dialer, strategy, client, transport}
+}
+
+func (d *DialerWrapper) 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.client.Lookup(ctx, d.transport, destination.Fqdn, d.strategy)
+	if err != nil {
+		return nil, err
+	}
+	var conn net.Conn
+	var connErrors []error
+	for _, address := range addresses {
+		conn, err = d.dialer.DialContext(ctx, network, M.SocksaddrFromAddrPort(address, destination.Port))
+		if err != nil {
+			connErrors = append(connErrors, err)
+		}
+		return conn, nil
+	}
+	return nil, E.Errors(connErrors...)
+}
+
+func (d *DialerWrapper) ListenPacket(ctx context.Context, destination M.Socksaddr) (net.PacketConn, error) {
+	if destination.IsIP() {
+		return d.dialer.ListenPacket(ctx, destination)
+	}
+	addresses, err := d.client.Lookup(ctx, d.transport, destination.Fqdn, d.strategy)
+	if err != nil {
+		return nil, err
+	}
+	var conn net.PacketConn
+	var connErrors []error
+	for _, address := range addresses {
+		conn, err = d.dialer.ListenPacket(ctx, M.SocksaddrFromAddrPort(address, destination.Port))
+		if err != nil {
+			connErrors = append(connErrors, err)
+		}
+		return conn, nil
+	}
+	return nil, E.Errors(connErrors...)
+}
+
+func (d *DialerWrapper) Upstream() any {
+	return d.dialer
+}