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/tgtest/services/file/upload.go

@@ -0,0 +1,115 @@
+package file
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/go-faster/errors"
+	"go.uber.org/multierr"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/constant"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tg"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tgerr"
+)
+
+// https://core.telegram.org/api/files#uploading-files
+const (
+	// Each part should have a sequence number, file_part, with a value ranging from 0 to 3,999.
+	uploadPartsLimit = constant.UploadMaxParts
+
+	// `part_size % 1024 = 0` (divisible by 1KB)
+	uploadPaddingPartSize = constant.UploadPadding
+	// `524288 % part_size = 0` (512KB must be evenly divisible by part_size)
+	uploadMaximumPartSize = constant.UploadMaxPartSize
+)
+
+type upload interface {
+	// GetFileID returns random file identifier created by the client.
+	GetFileID() int64
+	// GetFilePart returns numerical order of a part.
+	GetFilePart() int
+	// GetBytes returns binary data, content of a part.
+	GetBytes() []byte
+}
+
+func validatePartSize(got, stored int) *tgerr.Error {
+	switch {
+	case got == 0:
+		return tgerr.New(400, tg.ErrFilePartEmpty)
+	case got > uploadMaximumPartSize:
+		return tgerr.New(400, tg.ErrFilePartTooBig)
+	}
+
+	if stored == 0 {
+		return nil
+	}
+
+	switch {
+	case got != stored:
+		return tgerr.New(400, tg.ErrFilePartSizeChanged)
+	case uploadMaximumPartSize%got != 0,
+		got%uploadPaddingPartSize != 0:
+		return tgerr.New(400, tg.ErrFilePartSizeInvalid)
+	default:
+		return nil
+	}
+}
+
+func (m *Service) write(ctx context.Context, request upload) (err error) {
+	// TODO(tdakkota): Better way to handle user id. For now we haven't auth service to pair
+	//  user ID and authkey
+	id, ok := ctx.Value("user_id").(int)
+	if !ok {
+		id = 10
+	}
+
+	file, err := m.storage.Open(fmt.Sprintf("%d_%d", id, request.GetFileID()))
+	if err != nil {
+		return errors.Wrap(err, "open file")
+	}
+	defer func() {
+		multierr.AppendInto(&err, file.Close())
+	}()
+
+	part := request.GetFilePart()
+	if part < 0 || part > uploadPartsLimit {
+		return tgerr.New(400, tg.ErrFilePartInvalid)
+	}
+	data := request.GetBytes()
+	partSize := file.PartSize()
+	if err := validatePartSize(len(data), partSize); err != nil {
+		return err
+	}
+	if partSize == 0 {
+		partSize = len(data)
+		file.SetPartSize(partSize)
+	}
+
+	offset := int64(partSize * part)
+	if _, err := file.WriteAt(data, offset); err != nil {
+		return errors.Errorf("write at %d-%d", offset, offset+int64(len(data)))
+	}
+
+	return nil
+}
+
+func (m *Service) UploadSaveFilePart(ctx context.Context, request *tg.UploadSaveFilePartRequest) (bool, error) {
+	if err := m.write(ctx, request); err != nil {
+		return false, err
+	}
+
+	return true, nil
+}
+
+func (m *Service) UploadSaveBigFilePart(ctx context.Context, request *tg.UploadSaveBigFilePartRequest) (bool, error) {
+	part := request.FileTotalParts
+	if part < 0 || part > uploadPartsLimit {
+		return false, tgerr.New(400, tg.ErrFilePartsInvalid)
+	}
+
+	if err := m.write(ctx, request); err != nil {
+		return false, err
+	}
+
+	return true, nil
+}