mtg/telegram/direct.go

package telegram

import (
	"context"
	"net"

	"github.com/juju/errors"

	"github.com/9seconds/mtg/config"
	"github.com/9seconds/mtg/mtproto"
	"github.com/9seconds/mtg/obfuscated2"
	"github.com/9seconds/mtg/wrappers"
)

const (
	directV4DefaultIdx = 1
	directV6DefaultIdx = 1
)

var (
	directV4Addresses = map[int16][]string{
		0: {"149.154.175.50:443"},
		1: {"149.154.167.51:443"},
		2: {"149.154.175.100:443"},
		3: {"149.154.167.91:443"},
		4: {"149.154.171.5:443"},
	}
	directV6Addresses = map[int16][]string{
		0: {"[2001:b28:f23d:f001::a]:443"},
		1: {"[2001:67c:04e8:f002::a]:443"},
		2: {"[2001:b28:f23d:f003::a]:443"},
		3: {"[2001:67c:04e8:f004::a]:443"},
		4: {"[2001:b28:f23f:f005::a]:443"},
	}
)

type directTelegram struct {
	baseTelegram
}

func (t *directTelegram) Dial(ctx context.Context, cancel context.CancelFunc,
	connID string, connOpts *mtproto.ConnectionOpts) (wrappers.StreamReadWriteCloser, error) {
	dc := connOpts.DC
	if dc < 0 {
		dc = -dc
	} else if dc == 0 {
		dc = 1
	}

	return t.baseTelegram.dial(ctx, cancel, dc-1, connID, connOpts.ConnectionProto)
}

func (t *directTelegram) Init(connOpts *mtproto.ConnectionOpts,
	conn wrappers.StreamReadWriteCloser) (wrappers.Wrap, error) {
	obfs2, frame := obfuscated2.MakeTelegramObfuscated2Frame(connOpts)

	if _, err := conn.Write(frame); err != nil {
		return nil, errors.Annotate(err, "Cannot write hadnshake frame")
	}

	return wrappers.NewStreamCipher(conn, obfs2.Encryptor, obfs2.Decryptor), nil
}

// NewDirectTelegram returns Telegram instance which connects directly
// to Telegram bypassing middleproxies.
func NewDirectTelegram(conf *config.Config) Telegram {
	return &directTelegram{
		baseTelegram: baseTelegram{
			dialer: tgDialer{
				Dialer: net.Dialer{Timeout: telegramDialTimeout},
				conf:   conf,
			},
			v4DefaultIdx: directV4DefaultIdx,
			v6DefaultIdx: directV6DefaultIdx,
			v4Addresses:  directV4Addresses,
			v6Addresses:  directV6Addresses,
		},
	}
}