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/exchange/proto.go

@@ -0,0 +1,93 @@
+package exchange
+
+import (
+	"context"
+	"time"
+
+	"github.com/go-faster/errors"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/bin"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/clock"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/proto"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/proto/codec"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/transport"
+)
+
+type unencryptedWriter struct {
+	clock   clock.Clock
+	conn    transport.Conn
+	timeout time.Duration
+	input   proto.MessageType
+	output  proto.MessageType
+}
+
+func (w unencryptedWriter) writeUnencrypted(ctx context.Context, b *bin.Buffer, data bin.Encoder) error {
+	b.Reset()
+
+	if err := data.Encode(b); err != nil {
+		return err
+	}
+	msg := proto.UnencryptedMessage{
+		MessageID:   int64(proto.NewMessageID(w.clock.Now(), w.output)),
+		MessageData: b.Copy(),
+	}
+	b.Reset()
+	if err := msg.Encode(b); err != nil {
+		return err
+	}
+
+	ctx, cancel := context.WithTimeout(ctx, w.timeout)
+	defer cancel()
+	return w.conn.Send(ctx, b)
+}
+
+func (w unencryptedWriter) tryRead(ctx context.Context, b *bin.Buffer) error {
+	ctx, cancel := context.WithTimeout(ctx, w.timeout)
+	defer cancel()
+
+	if err := w.conn.Recv(ctx, b); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (w unencryptedWriter) isClient() bool {
+	return w.output == proto.MessageFromClient
+}
+
+func (w unencryptedWriter) readUnencrypted(ctx context.Context, b *bin.Buffer, data bin.Decoder) error {
+	b.Reset()
+
+	for {
+		if err := w.tryRead(ctx, b); err != nil {
+			var protocolErr *codec.ProtocolErr
+			if w.isClient() &&
+				errors.As(err, &protocolErr) &&
+				protocolErr.Code == codec.CodeAuthKeyNotFound {
+				continue
+			}
+			return err
+		}
+
+		break
+	}
+
+	var msg proto.UnencryptedMessage
+	if err := msg.Decode(b); err != nil {
+		return err
+	}
+	if err := w.checkMsgID(msg.MessageID); err != nil {
+		return err
+	}
+	b.ResetTo(msg.MessageData)
+
+	return data.Decode(b)
+}
+
+func (w unencryptedWriter) checkMsgID(id int64) error {
+	if proto.MessageID(id).Type() != w.input {
+		return errors.New("bad msg type")
+	}
+	return nil
+}