Some refactorings for telegram package

cli/proxy.go

 	if err := stats.Init(ctx); err != nil {
 		Fatal(err)
 	}
-	telegram.MiddleInit()
+	telegram.Init()
 
 	proxyListener, err := net.Listen("tcp", config.C.Bind.String())
 	if err != nil {

telegram/base.go

 	"fmt"
 	"math/rand"
 	"net"
-	"time"
 
 	"github.com/9seconds/mtg/conntypes"
 	"github.com/9seconds/mtg/utils"
 	"github.com/9seconds/mtg/wrappers"
 )
 
-const telegramDialTimeout = 10 * time.Second
-
 type baseTelegram struct {
 	dialer net.Dialer
 

telegram/direct.go

 package telegram
 
-import (
-	"net"
-
-	"github.com/9seconds/mtg/conntypes"
-)
+import "github.com/9seconds/mtg/conntypes"
 
 const (
 	directV4DefaultIdx conntypes.DC = 1
 
 	return d.baseTelegram.dial(dc-1, protocol)
 }
-
-var Direct = &directTelegram{
-	baseTelegram: baseTelegram{
-		dialer:      net.Dialer{Timeout: telegramDialTimeout},
-		v4DefaultDC: directV4DefaultIdx,
-		V6DefaultDC: directV6DefaultIdx,
-		v4Addresses: directV4Addresses,
-		v6Addresses: directV6Addresses,
-	},
-}

telegram/init.go

+package telegram
+
+import (
+	"net"
+	"sync"
+	"time"
+)
+
+const telegramDialTimeout = 10 * time.Second
+
+var (
+	Direct Telegram
+	Middle Telegram
+
+	initOnce sync.Once
+)
+
+func Init() {
+	initOnce.Do(func() {
+		Direct = &directTelegram{
+			baseTelegram: baseTelegram{
+				dialer:      net.Dialer{Timeout: telegramDialTimeout},
+				v4DefaultDC: directV4DefaultIdx,
+				V6DefaultDC: directV6DefaultIdx,
+				v4Addresses: directV4Addresses,
+				v6Addresses: directV6Addresses,
+			},
+		}
+
+		tg := &middleTelegram{
+			baseTelegram: baseTelegram{
+				dialer: net.Dialer{Timeout: telegramDialTimeout},
+			},
+		}
+		if err := tg.update(); err != nil {
+			panic(err)
+		}
+		go tg.backgroundUpdate()
+
+		Middle = tg
+	})
+}

telegram/interfaces.go

 package telegram
 
-import  "github.com/9seconds/mtg/conntypes"
+import "github.com/9seconds/mtg/conntypes"
 
 type Telegram interface {
 	Dial(conntypes.DC, conntypes.ConnectionProtocol) (conntypes.StreamReadWriteCloser, error)

telegram/middle.go

 
 import (
 	"fmt"
-	"net"
 	"sync"
 	"time"
 
 
 const middleTelegramBackgroundUpdateEvery = time.Hour
 
-var Middle Telegram
-
 type middleTelegram struct {
 	baseTelegram
 
 
 	return m.baseTelegram.dial(dc, protocol)
 }
-
-func MiddleInit() {
-	tg := &middleTelegram{
-		baseTelegram: baseTelegram{
-			dialer: net.Dialer{Timeout: telegramDialTimeout},
-		},
-	}
-	if err := tg.update(); err != nil {
-		panic(err)
-	}
-	go tg.backgroundUpdate()
-
-	Middle = tg
-}