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/session/tdesktop.go

@@ -0,0 +1,88 @@
+package session
+
+import (
+	"github.com/go-faster/errors"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/session/tdesktop"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/telegram/dcs"
+	"go.mau.fi/mautrix-telegram/pkg/gotd/tg"
+)
+
+func findDCAddr(list []tg.DCOption, dcID int) string {
+	for _, opt := range list {
+		if opt.ID != dcID {
+			continue
+		}
+		if opt.TCPObfuscatedOnly ||
+			opt.CDN ||
+			opt.MediaOnly {
+			continue
+		}
+
+		return opt.IPAddress
+	}
+
+	return ""
+}
+
+func mapConfig(mainDC int, cfg tdesktop.MTPConfig) Config {
+	var opts []tg.DCOption
+	for _, dc := range cfg.DCOptions.Options {
+		opts = append(opts, tg.DCOption{
+			Flags:             dc.Flags,
+			Ipv6:              dc.IPv6(),
+			MediaOnly:         dc.MediaOnly(),
+			TCPObfuscatedOnly: dc.TCPOOnly(),
+			CDN:               dc.CDN(),
+			Static:            dc.Static(),
+			ID:                int(dc.ID),
+			IPAddress:         dc.IP,
+			Port:              int(dc.Port),
+			Secret:            dc.Secret,
+		})
+	}
+	return Config{
+		DCOptions:       opts,
+		ThisDC:          mainDC,
+		WebfileDCID:     int(cfg.WebFileDCID),
+		DCTxtDomainName: cfg.TxtDomainString,
+		BlockedMode:     cfg.BlockedMode,
+	}
+}
+
+// TDesktopSession converts TDesktop's Account to Data.
+func TDesktopSession(account tdesktop.Account) (*Data, error) {
+	auth := account.Authorization
+	cfg := account.Config
+	dc := auth.MainDC
+
+	key, ok := auth.Keys[dc]
+	if !ok {
+		return nil, errors.Errorf("key for main DC (%d) not found", dc)
+	}
+	keyID := key.ID()
+
+	mappedCfg := mapConfig(dc, cfg)
+	addr := findDCAddr(mappedCfg.DCOptions, dc)
+	if addr == "" {
+		// Fallback to built-in addrs.
+		var list dcs.List
+		if !cfg.Environment.Test() {
+			list = dcs.Prod()
+		} else {
+			list = dcs.Test()
+		}
+		addr = findDCAddr(list.Options, dc)
+		if addr == "" {
+			return nil, errors.Errorf("can't find address for DC %d", dc)
+		}
+	}
+
+	return &Data{
+		DC:        dc,
+		Addr:      addr,
+		Config:    mappedCfg,
+		AuthKey:   key[:],
+		AuthKeyID: keyID[:],
+	}, nil
+}