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/telegram/dcs/websocket.go

@@ -0,0 +1,103 @@
+package dcs
+
+import (
+	"context"
+	"io"
+
+	"github.com/coder/websocket"
+	"github.com/go-faster/errors"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/crypto"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/mtproxy"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/mtproxy/obfuscator"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/proto/codec"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/transport"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/wsutil"
+)
+
+var _ Resolver = ws{}
+
+type ws struct {
+	dialOptions *websocket.DialOptions
+	protocol    protocol
+
+	tag  [4]byte
+	rand io.Reader
+}
+
+func (w ws) connect(ctx context.Context, dc int, domains map[int]string) (transport.Conn, error) {
+	addr, ok := domains[dc]
+	if !ok {
+		return nil, errors.Errorf("domain for %d not found", dc)
+	}
+
+	conn, resp, err := websocket.Dial(ctx, addr, w.dialOptions)
+	if resp != nil && resp.Body != nil {
+		_ = resp.Body.Close()
+	}
+	if err != nil {
+		return nil, errors.Wrap(err, "dial ws")
+	}
+	obsConn := obfuscator.Obfuscated2(w.rand, wsutil.NetConn(conn))
+
+	if err := obsConn.Handshake(w.tag, dc, mtproxy.Secret{
+		Secret: nil,
+		Type:   mtproxy.Simple,
+	}); err != nil {
+		return nil, errors.Wrap(err, "handshake")
+	}
+
+	transportConn, err := w.protocol.Handshake(obsConn)
+	if err != nil {
+		return nil, errors.Wrap(err, "transport handshake")
+	}
+
+	return transportConn, nil
+}
+
+func (w ws) Primary(ctx context.Context, dc int, list List) (transport.Conn, error) {
+	return w.connect(ctx, dc, list.Domains)
+}
+
+func (w ws) MediaOnly(ctx context.Context, dc int, list List) (transport.Conn, error) {
+	return nil, errors.Errorf("can't resolve %d: MediaOnly is unsupported", dc)
+}
+
+func (w ws) CDN(ctx context.Context, dc int, list List) (transport.Conn, error) {
+	return nil, errors.Errorf("can't resolve %d: CDN is unsupported", dc)
+}
+
+// WebsocketOptions is Websocket resolver creation options.
+type WebsocketOptions struct {
+	// Dialer specifies the websocket dialer.
+	// If Dialer is nil, then the resolver dials using websocket.DefaultDialer.
+	DialOptions *websocket.DialOptions
+	// Random source for MTProxy obfuscator.
+	Rand io.Reader
+}
+
+func (m *WebsocketOptions) setDefaults() {
+	if m.DialOptions == nil {
+		m.DialOptions = &websocket.DialOptions{Subprotocols: []string{
+			"binary",
+		}}
+	}
+	if m.Rand == nil {
+		m.Rand = crypto.DefaultRand()
+	}
+}
+
+// Websocket creates Websocket DC resolver.
+//
+// See https://core.telegram.org/mtproto/transports#websocket.
+func Websocket(opts WebsocketOptions) Resolver {
+	cdc := codec.Intermediate{}
+	opts.setDefaults()
+
+	return ws{
+		dialOptions: opts.DialOptions,
+		protocol:    transport.NewProtocol(func() transport.Codec { return codec.NoHeader{Codec: cdc} }),
+		tag:         cdc.ObfuscatedTag(),
+		rand:        opts.Rand,
+	}
+}