move gotd fork into repo. (#111)

- update to latest telegram layer
- remove some references to fields in tg.Entities that don't exist in
the schema
- originally added here:
https://github.com/beeper/td/commit/820929062a2ba0104397bc01235ab58a9cff780e
  - referenced here
-
https://github.com/mautrix/telegramgo/commit/124f0967ed195b5a380c9bd02e170ada9710dde3
-
https://github.com/mautrix/telegramgo/commit/4205047aab2e0639217148b5d125bfaab668bd8e

pkg/gotd/transport/websocket.go

@@ -0,0 +1,131 @@
+package transport
+
+import (
+	"bytes"
+	"io"
+	"net"
+	"net/http"
+
+	"github.com/coder/websocket"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/mtproxy/obfuscated2"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/proto/codec"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tdsync"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/wsutil"
+)
+
+type wsListener struct {
+	addr   net.Addr
+	ch     chan *wsServerConn
+	closed *tdsync.Ready
+}
+
+// WebsocketListener creates new MTProto Websocket listener.
+func WebsocketListener(addr net.Addr) (net.Listener, http.Handler) {
+	l := wsListener{
+		addr:   addr,
+		ch:     make(chan *wsServerConn, 1),
+		closed: tdsync.NewReady(),
+	}
+	return l, l
+}
+
+func (l wsListener) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	wsConn, err := websocket.Accept(w, r, &websocket.AcceptOptions{
+		Subprotocols: []string{"binary"},
+	})
+	if err != nil {
+		w.WriteHeader(400)
+		return
+	}
+	defer func() {
+		_ = wsConn.Close(websocket.StatusNormalClosure, "Close")
+	}()
+
+	conn := wsutil.NetConn(wsConn)
+	rw, md, err := obfuscated2.Accept(conn, nil)
+	if err != nil {
+		w.WriteHeader(400)
+		return
+	}
+
+	var tag *bytes.Reader
+	if md.Protocol[0] == codec.AbridgedClientStart[0] {
+		// Abridged sends only byte for tag.
+		tag = bytes.NewReader(md.Protocol[:1])
+	} else {
+		tag = bytes.NewReader(md.Protocol[:])
+	}
+
+	accepted := &wsServerConn{
+		closed: *tdsync.NewReady(),
+		// Add codec tag in the begin of stream to emulate TCP fully.
+		// MTProto sends codec tag in plain TCP connections, but not in obfuscated2 (Websocket/MTProxy).
+		reader: io.MultiReader(tag, rw),
+		writer: rw,
+		Conn:   conn,
+	}
+
+	reqCtx := r.Context().Done()
+	closed := l.closed.Ready()
+
+	// Pass connection to the Accept().
+	select {
+	case <-reqCtx:
+		return
+	case <-closed:
+		return
+	case l.ch <- accepted:
+	}
+
+	// Await close or shutdown.
+	select {
+	case <-reqCtx:
+		return
+	case <-closed:
+		return
+	case <-accepted.closed.Ready():
+	}
+}
+
+func (l wsListener) Accept() (net.Conn, error) {
+	r := l.closed.Ready()
+
+	for {
+		select {
+		case <-r:
+			return nil, net.ErrClosed
+		case conn := <-l.ch:
+			return conn, nil
+		}
+	}
+}
+
+func (l wsListener) Close() error {
+	l.closed.Signal()
+	return nil
+}
+
+func (l wsListener) Addr() net.Addr {
+	return l.addr
+}
+
+type wsServerConn struct {
+	closed tdsync.Ready
+	reader io.Reader
+	writer io.Writer
+	net.Conn
+}
+
+func (c *wsServerConn) Read(p []byte) (int, error) {
+	return c.reader.Read(p)
+}
+
+func (c *wsServerConn) Write(p []byte) (int, error) {
+	return c.writer.Write(p)
+}
+
+func (c *wsServerConn) Close() error {
+	c.closed.Signal()
+	return nil
+}