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/mtp_dcoptions.go

@@ -0,0 +1,128 @@
+package tdesktop
+
+import (
+	"github.com/go-faster/errors"
+
+	"go.mau.fi/mautrix-telegram/pkg/gotd/bin"
+)
+
+// MTPDCOption is a Telegram Desktop storage structure which stores DC info.
+//
+// See https://github.com/telegramdesktop/tdesktop/blob/v2.9.8/Telegram/SourceFiles/mtproto/mtproto_dc_options.h.
+type MTPDCOption struct {
+	ID     int32
+	Flags  bin.Fields
+	Port   int32
+	IP     string
+	Secret []byte
+}
+
+// IPv6 denotes that the specified IP is an IPv6 address.
+func (m MTPDCOption) IPv6() bool {
+	return m.Flags.Has(0)
+}
+
+// MediaOnly denotes that this DC should only be used to download or upload files.
+func (m MTPDCOption) MediaOnly() bool {
+	return m.Flags.Has(1)
+}
+
+// TCPOOnly denotes that this DC only supports connection with transport obfuscation.
+func (m MTPDCOption) TCPOOnly() bool {
+	return m.Flags.Has(2)
+}
+
+// CDN denotes that this is a CDN DC.
+func (m MTPDCOption) CDN() bool {
+	return m.Flags.Has(3)
+}
+
+// Static denotes that this IP should be used when connecting through a proxy.
+func (m MTPDCOption) Static() bool {
+	return m.Flags.Has(4)
+}
+
+func (m *MTPDCOption) deserialize(r *qtReader, version int32) error {
+	id, err := r.readInt32()
+	if err != nil {
+		return errors.Wrap(err, "read id")
+	}
+	m.ID = id
+
+	flags, err := r.readUint32()
+	if err != nil {
+		return errors.Wrap(err, "read flags")
+	}
+	m.Flags = bin.Fields(flags)
+
+	port, err := r.readInt32()
+	if err != nil {
+		return errors.Wrap(err, "read port")
+	}
+	m.Port = port
+
+	const maxIPSize = 45
+	ip, err := r.readString()
+	if err != nil {
+		return errors.Wrap(err, "read ip")
+	}
+	if l := len(ip); l > maxIPSize {
+		return errors.Errorf("too big IP string (%d > %d)", l, maxIPSize)
+	}
+	m.IP = ip
+
+	if version > 0 {
+		const maxSecretSize = 32
+		secret, err := r.readBytes()
+		if err != nil {
+			return errors.Wrap(err, "read secret")
+		}
+		if l := len(secret); l > maxSecretSize {
+			return errors.Errorf("too big DC secret (%d > %d)", l, maxSecretSize)
+		}
+		m.Secret = secret
+	}
+
+	return nil
+}
+
+// MTPDCOptions is a Telegram Desktop storage structure which stores DCs info.
+//
+// See https://github.com/telegramdesktop/tdesktop/blob/v2.9.8/Telegram/SourceFiles/mtproto/mtproto_dc_options.cpp#L479.
+type MTPDCOptions struct {
+	Options []MTPDCOption
+}
+
+func (m *MTPDCOptions) deserialize(r *qtReader) error {
+	minusVersion, err := r.readInt32()
+	if err != nil {
+		return errors.Wrap(err, "read version")
+	}
+
+	var version int32
+	if minusVersion < 0 {
+		version = -minusVersion
+	}
+
+	var count int32
+	if version > 0 {
+		c, err := r.readInt32()
+		if err != nil {
+			return errors.Wrap(err, "read count")
+		}
+		count = c
+	} else {
+		count = minusVersion
+	}
+
+	for i := 0; i < int(count); i++ {
+		var o MTPDCOption
+		if err := o.deserialize(r, version); err != nil {
+			return errors.Errorf("read option %d: %w", i, err)
+		}
+		m.Options = append(m.Options, o)
+	}
+
+	// TODO(tdakkota): Read CDN keys.
+	return nil
+}