Add dns transports

dns/transport_https.go

@@ -0,0 +1,95 @@
+package dns
+
+import (
+	"bytes"
+	"context"
+	"net"
+	"net/http"
+	"net/netip"
+	"os"
+
+	"github.com/sagernet/sing/common"
+	"github.com/sagernet/sing/common/buf"
+	M "github.com/sagernet/sing/common/metadata"
+	N "github.com/sagernet/sing/common/network"
+
+	C "github.com/sagernet/sing-box/constant"
+
+	"golang.org/x/net/dns/dnsmessage"
+)
+
+const dnsMimeType = "application/dns-message"
+
+var _ Transport = (*HTTPSTransport)(nil)
+
+type HTTPSTransport struct {
+	destination string
+	transport   *http.Transport
+}
+
+func NewHTTPSTransport(dialer N.Dialer, destination string) *HTTPSTransport {
+	return &HTTPSTransport{
+		destination: destination,
+		transport: &http.Transport{
+			ForceAttemptHTTP2: true,
+			DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
+				return dialer.DialContext(ctx, network, M.ParseSocksaddr(addr))
+			},
+		},
+	}
+}
+
+func (t *HTTPSTransport) Start() error {
+	return nil
+}
+
+func (t *HTTPSTransport) Close() error {
+	t.transport.CloseIdleConnections()
+	return nil
+}
+
+func (t *HTTPSTransport) Raw() bool {
+	return true
+}
+
+func (t *HTTPSTransport) Exchange(ctx context.Context, message *dnsmessage.Message) (*dnsmessage.Message, error) {
+	message.ID = 0
+	_buffer := buf.StackNewSize(1024)
+	defer common.KeepAlive(_buffer)
+	buffer := common.Dup(_buffer)
+	defer buffer.Release()
+	rawMessage, err := message.AppendPack(buffer.Index(0))
+	if err != nil {
+		return nil, err
+	}
+	buffer.Truncate(len(rawMessage))
+	request, err := http.NewRequest(http.MethodPost, t.destination, bytes.NewReader(buffer.Bytes()))
+	if err != nil {
+		return nil, err
+	}
+	request.WithContext(ctx)
+	request.Header.Set("content-type", dnsMimeType)
+	request.Header.Set("accept", dnsMimeType)
+
+	client := &http.Client{Transport: t.transport}
+	response, err := client.Do(request)
+	if err != nil {
+		return nil, err
+	}
+	defer response.Body.Close()
+	buffer.FullReset()
+	_, err = buffer.ReadAllFrom(response.Body)
+	if err != nil {
+		return nil, err
+	}
+	var responseMessage dnsmessage.Message
+	err = responseMessage.Unpack(buffer.Bytes())
+	if err != nil {
+		return nil, err
+	}
+	return &responseMessage, nil
+}
+
+func (t *HTTPSTransport) Lookup(ctx context.Context, domain string, strategy C.DomainStrategy) ([]netip.Addr, error) {
+	return nil, os.ErrInvalid
+}