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/builder.go

@@ -0,0 +1,174 @@
+package telegram
+
+import (
+	"context"
+	"io"
+	"os"
+	"path/filepath"
+	"strconv"
+	"time"
+
+	"github.com/cenkalti/backoff/v4"
+	"github.com/go-faster/errors"
+	"go.uber.org/zap"
+	"golang.org/x/net/proxy"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/clock"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/crypto"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/session"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/telegram/auth"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/telegram/dcs"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tgerr"
+)
+
+func sessionDir() (string, error) {
+	dir, ok := os.LookupEnv("SESSION_DIR")
+	if ok {
+		return filepath.Abs(dir)
+	}
+
+	dir, err := os.UserHomeDir()
+	if err != nil {
+		dir = "."
+	}
+
+	return filepath.Abs(filepath.Join(dir, ".td"))
+}
+
+// OptionsFromEnvironment fills unfilled field in opts parameter
+// using environment variables.
+//
+// Variables:
+//
+//	SESSION_FILE:        path to session file
+//	SESSION_DIR:         path to session directory, if SESSION_FILE is not set
+//	ALL_PROXY, NO_PROXY: see https://pkg.go.dev/golang.org/x/net/proxy#FromEnvironment
+func OptionsFromEnvironment(opts Options) (Options, error) {
+	// Setting up session storage if not provided.
+	if opts.SessionStorage == nil {
+		sessionFile, ok := os.LookupEnv("SESSION_FILE")
+		if !ok {
+			dir, err := sessionDir()
+			if err != nil {
+				return Options{}, errors.Wrap(err, "SESSION_DIR not set or invalid")
+			}
+			sessionFile = filepath.Join(dir, "session.json")
+		}
+
+		dir, _ := filepath.Split(sessionFile)
+		if err := os.MkdirAll(dir, 0700); err != nil {
+			return Options{}, errors.Wrap(err, "session dir creation")
+		}
+
+		opts.SessionStorage = &session.FileStorage{
+			Path: sessionFile,
+		}
+	}
+
+	if opts.Resolver == nil {
+		opts.Resolver = dcs.Plain(dcs.PlainOptions{
+			Dial: proxy.Dial,
+		})
+	}
+
+	return opts, nil
+}
+
+// ClientFromEnvironment creates client using OptionsFromEnvironment
+// but does not connect to server.
+//
+// Variables:
+//
+//	APP_ID:   app_id of Telegram app.
+//	APP_HASH: app_hash of Telegram app.
+func ClientFromEnvironment(opts Options) (*Client, error) {
+	appID, err := strconv.Atoi(os.Getenv("APP_ID"))
+	if err != nil {
+		return nil, errors.Wrap(err, "APP_ID not set or invalid")
+	}
+
+	appHash := os.Getenv("APP_HASH")
+	if appHash == "" {
+		return nil, errors.New("no APP_HASH provided")
+	}
+
+	opts, err = OptionsFromEnvironment(opts)
+	if err != nil {
+		return nil, err
+	}
+
+	return NewClient(appID, appHash, opts), nil
+}
+
+func retry(ctx context.Context, logger *zap.Logger, cb func(ctx context.Context) error) error {
+	b := backoff.WithContext(backoff.NewExponentialBackOff(), ctx)
+
+	// List of known retryable RPC error types.
+	retryableErrors := []string{
+		"NEED_MEMBER_INVALID",
+		"AUTH_KEY_UNREGISTERED",
+		"API_ID_PUBLISHED_FLOOD",
+	}
+
+	return backoff.Retry(func() error {
+		if err := cb(ctx); err != nil {
+			logger.Warn("TestClient run failed", zap.Error(err))
+
+			if tgerr.Is(err, retryableErrors...) {
+				return err
+			}
+			if timeout, ok := AsFloodWait(err); ok {
+				timer := clock.System.Timer(timeout + 1*time.Second)
+				defer clock.StopTimer(timer)
+
+				select {
+				case <-timer.C():
+					return err
+				case <-ctx.Done():
+					return ctx.Err()
+				}
+			}
+			if errors.Is(err, io.EOF) || errors.Is(err, io.ErrUnexpectedEOF) {
+				// Possibly server closed connection.
+				return err
+			}
+
+			return backoff.Permanent(err)
+		}
+
+		return nil
+	}, b)
+}
+
+// TestClient creates and authenticates user telegram.Client
+// using Telegram test server.
+func TestClient(ctx context.Context, opts Options, cb func(ctx context.Context, client *Client) error) error {
+	if opts.DC == 0 {
+		opts.DC = 2
+	}
+	if opts.DCList.Zero() {
+		opts.DCList = dcs.Test()
+	}
+
+	logger := zap.NewNop()
+	if opts.Logger != nil {
+		logger = opts.Logger.Named("test")
+	}
+
+	// Sometimes testing server can return "AUTH_KEY_UNREGISTERED" error.
+	// It is expected and client implementation is unlikely to cause
+	// such errors, so just doing retries using backoff.
+	return retry(ctx, logger, func(retryCtx context.Context) error {
+		client := NewClient(TestAppID, TestAppHash, opts)
+		return client.Run(retryCtx, func(runCtx context.Context) error {
+			if err := client.Auth().IfNecessary(runCtx, auth.NewFlow(
+				auth.Test(crypto.DefaultRand(), opts.DC),
+				auth.SendCodeOptions{},
+			)); err != nil {
+				return errors.Wrap(err, "auth flow")
+			}
+
+			return cb(runCtx, client)
+		})
+	})
+}