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/session.go

@@ -0,0 +1,125 @@
+package telegram
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/go-faster/errors"
+	"go.uber.org/zap"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/crypto"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/mtproto"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/pool"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/session"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tg"
+)
+
+func (c *Client) restoreConnection(ctx context.Context) error {
+	if c.storage == nil {
+		return nil
+	}
+
+	data, err := c.storage.Load(ctx)
+	if errors.Is(err, session.ErrNotFound) {
+		return nil
+	}
+	if err != nil {
+		return errors.Wrap(err, "load")
+	}
+
+	// If file does not contain DC ID, so we use DC from options.
+	prev := c.session.Load()
+	if data.DC == 0 {
+		data.DC = prev.DC
+	}
+
+	// Restoring persisted auth key.
+	var key crypto.AuthKey
+	copy(key.Value[:], data.AuthKey)
+	copy(key.ID[:], data.AuthKeyID)
+
+	if key.Value.ID() != key.ID {
+		return errors.New("corrupted key")
+	}
+
+	// Re-initializing connection from persisted state.
+	c.log.Info("Connection restored from state",
+		zap.String("addr", data.Addr),
+		zap.String("key_id", fmt.Sprintf("%x", data.AuthKeyID)),
+	)
+
+	c.connMux.Lock()
+	c.session.Store(pool.Session{
+		DC:      data.DC,
+		AuthKey: key,
+		Salt:    data.Salt,
+	})
+	c.conn = c.createPrimaryConn(nil)
+	c.connMux.Unlock()
+
+	return nil
+}
+
+func (c *Client) saveSession(cfg tg.Config, s mtproto.Session) error {
+	if c.storage == nil {
+		return nil
+	}
+
+	data, err := c.storage.Load(c.ctx)
+	if errors.Is(err, session.ErrNotFound) {
+		// Initializing new state.
+		err = nil
+		data = &session.Data{}
+	}
+	if err != nil {
+		return errors.Wrap(err, "load")
+	}
+
+	// Updating previous data.
+	data.Config = session.ConfigFromTG(cfg)
+	data.AuthKey = s.Key.Value[:]
+	data.AuthKeyID = s.Key.ID[:]
+	data.DC = cfg.ThisDC
+	data.Salt = s.Salt
+
+	if err := c.storage.Save(c.ctx, data); err != nil {
+		return errors.Wrap(err, "save")
+	}
+
+	c.log.Debug("Data saved",
+		zap.String("key_id", fmt.Sprintf("%x", data.AuthKeyID)),
+	)
+	return nil
+}
+
+func (c *Client) onSession(cfg tg.Config, s mtproto.Session) error {
+	c.sessionsMux.Lock()
+	c.sessions[cfg.ThisDC] = pool.NewSyncSession(pool.Session{
+		DC:      cfg.ThisDC,
+		Salt:    s.Salt,
+		AuthKey: s.Key,
+	})
+	c.sessionsMux.Unlock()
+
+	primaryDC := c.session.Load().DC
+	// Do not save session for non-primary DC.
+	if cfg.ThisDC != 0 && primaryDC != 0 && primaryDC != cfg.ThisDC {
+		return nil
+	}
+
+	c.connMux.Lock()
+	c.session.Store(pool.Session{
+		DC:      cfg.ThisDC,
+		Salt:    s.Salt,
+		AuthKey: s.Key,
+	})
+	c.cfg.Store(cfg)
+	c.onReady()
+	c.connMux.Unlock()
+
+	if err := c.saveSession(cfg, s); err != nil {
+		return errors.Wrap(err, "save")
+	}
+
+	return nil
+}