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/mtproto/handle_bad_msg.go

@@ -0,0 +1,68 @@
+package mtproto
+
+import (
+	"fmt"
+
+	"github.com/go-faster/errors"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/bin"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/mt"
+)
+
+type badMessageError struct {
+	Code    int
+	NewSalt int64
+}
+
+const (
+	codeMessageIDTooLow     = 16
+	codeMessageIDTooHigh    = 17
+	codeIncorrectServerSalt = 48
+)
+
+func (c badMessageError) Error() string {
+	description := map[int]string{
+		codeMessageIDTooLow:     "msg_id too low",
+		codeMessageIDTooHigh:    "msg_id too high",
+		codeIncorrectServerSalt: "incorrect server salt",
+
+		18: "incorrect two lower order msg_id bits",
+		19: "container msg_id is the same as msg_id of a previously received message",
+		20: "message too old",
+		32: "msg_seqno too low",
+		33: "msg_seqno too high",
+		34: "even msg_seqno expected, but odd received",
+		35: "odd msg_seqno expected, but even received",
+	}[c.Code]
+	if description == "" {
+		return fmt.Sprintf("bad msg error code %d", c.Code)
+	}
+	return description
+}
+
+func (c *Conn) handleBadMsg(b *bin.Buffer) error {
+	id, err := b.PeekID()
+	if err != nil {
+		return err
+	}
+	switch id {
+	case mt.BadMsgNotificationTypeID:
+		var bad mt.BadMsgNotification
+		if err := bad.Decode(b); err != nil {
+			return err
+		}
+
+		c.rpc.NotifyError(bad.BadMsgID, &badMessageError{Code: bad.ErrorCode})
+		return nil
+	case mt.BadServerSaltTypeID:
+		var bad mt.BadServerSalt
+		if err := bad.Decode(b); err != nil {
+			return err
+		}
+
+		c.rpc.NotifyError(bad.BadMsgID, &badMessageError{Code: bad.ErrorCode, NewSalt: bad.NewServerSalt})
+		return nil
+	default:
+		return errors.Errorf("unknown type id 0x%d", id)
+	}
+}