linting the code

Makefile

@@ -4,7 +4,7 @@ APP_NAME     := $(IMAGE_NAME)
 
 CC_BINARIES  := $(shell bash -c "echo -n $(APP_NAME)-{linux,freebsd,openbsd}-{386,amd64} $(APP_NAME)-linux-{arm,arm64}")
 
-GOLANGCI_LINT_VERSION := v1.15.0
+GOLANGCI_LINT_VERSION := v1.20.0
 
 VERSION_GO         := $(shell go version)
 VERSION_DATE       := $(shell date -Ru)
@@ -51,10 +51,6 @@ crosscompile: $(CC_BINARIES)
 crosscompile-dir:
 	@rm -rf "$(CC_DIR)" && mkdir -p "$(CC_DIR)"
 
-.PHONY: test
-test: vendor
-	@$(MOD_ON) go test -v ./...
-
 .PHONY: lint
 lint: vendor
 	@$(MOD_OFF) golangci-lint run

cli/generate.go

@@ -12,6 +12,7 @@ func Generate(secretType string) {
 	if _, err := rand.Read(data); err != nil {
 		panic(err)
 	}
+
 	secret := hex.EncodeToString(data)
 
 	switch secretType {

cli/proxy.go

@@ -19,10 +19,11 @@ import (
 	"github.com/9seconds/mtg/utils"
 )
 
-func Proxy() error {
+func Proxy() error { // nolint: funlen
 	ctx := utils.GetSignalContext()
 
 	atom := zap.NewAtomicLevel()
+
 	switch {
 	case config.C.Debug:
 		atom.SetLevel(zapcore.DebugLevel)
@@ -38,23 +39,28 @@ func Proxy() error {
 		zapcore.Lock(os.Stderr),
 		atom,
 	))
+
 	zap.ReplaceGlobals(logger)
 	defer logger.Sync() // nolint: errcheck
 
 	if err := config.InitPublicAddress(ctx); err != nil {
 		Fatal(err)
 	}
+
 	zap.S().Debugw("Configuration", "config", config.Printable())
 
 	if len(config.C.AdTag) > 0 {
 		zap.S().Infow("Use middle proxy connection to Telegram")
+
 		diff, err := ntp.Fetch()
 		if err != nil {
 			Fatal("Cannot fetch time data from NTP")
 		}
+
 		if diff > time.Second {
 			Fatal("Your local time is skewed and drift is bigger than a second. Please sync your time.")
 		}
+
 		go ntp.AutoUpdate()
 	} else {
 		zap.S().Infow("Use direct connection to Telegram")
@@ -62,10 +68,11 @@ func Proxy() error {
 
 	PrintJSONStdout(config.GetURLs())
 
-	antireplay.Init()
 	if err := stats.Init(ctx); err != nil {
 		Fatal(err)
 	}
+
+	antireplay.Init()
 	telegram.Init()
 	hub.Init(ctx)
 
@@ -73,6 +80,7 @@ func Proxy() error {
 	if err != nil {
 		Fatal(err)
 	}
+
 	go func() {
 		<-ctx.Done()
 		proxyListener.Close()

cli/utils.go

@@ -11,6 +11,7 @@ func Fatal(arg interface{}) {
 	if value, ok := arg.(error); ok {
 		arg = fmt.Errorf("fatal error: %+v", value)
 	}
+
 	PrintStderr(arg)
 	os.Exit(1)
 }

config/config.go

@@ -23,6 +23,7 @@ func (s SecretMode) String() string {
 	case SecretModeSecured:
 		return "secured"
 	}
+
 	return "tls"
 }
 
@@ -135,7 +136,7 @@ func Init(options ...Opt) error { // nolint: gocyclo, funlen
 			case "influxdb":
 				C.StatsdTagsFormat = statsd.InfluxDB
 			default:
-				return fmt.Errorf("Incorrect statsd tag %s", value)
+				return fmt.Errorf("incorrect statsd tag %s", value)
 			}
 		case OptionTypeStatsdTags:
 			C.StatsdTags = opt.Value.(map[string]string)
@@ -152,7 +153,7 @@ func Init(options ...Opt) error { // nolint: gocyclo, funlen
 		case OptionTypeAdtag:
 			C.AdTag = opt.Value.([]byte)
 		default:
-			return fmt.Errorf("Unknown tag %v", opt.Option)
+			return fmt.Errorf("unknown tag %v", opt.Option)
 		}
 	}
 
@@ -163,7 +164,7 @@ func Init(options ...Opt) error { // nolint: gocyclo, funlen
 	case len(C.Secret) == SimpleSecretLength:
 		C.SecretMode = SecretModeSimple
 	default:
-		return errors.New("Incorrect secret")
+		return errors.New("incorrect secret")
 	}
 
 	return nil
@@ -173,11 +174,13 @@ func InitPublicAddress(ctx context.Context) error {
 	if C.PublicIPv4.Port == 0 {
 		C.PublicIPv4.Port = C.Bind.Port
 	}
+
 	if C.PublicIPv6.Port == 0 {
 		C.PublicIPv6.Port = C.Bind.Port
 	}
 
 	foundAddress := C.PublicIPv4.IP != nil || C.PublicIPv6.IP != nil
+
 	if C.PublicIPv4.IP == nil {
 		ip, err := getGlobalIPv4(ctx)
 		if err != nil {
@@ -187,6 +190,7 @@ func InitPublicAddress(ctx context.Context) error {
 			foundAddress = true
 		}
 	}
+
 	if C.PublicIPv6.IP == nil {
 		ip, err := getGlobalIPv6(ctx)
 		if err != nil {
@@ -198,7 +202,7 @@ func InitPublicAddress(ctx context.Context) error {
 	}
 
 	if !foundAddress {
-		return errors.New("Cannot resolve any public address")
+		return errors.New("cannot resolve any public address")
 	}
 
 	return nil

config/global_ips.go

@@ -21,6 +21,7 @@ func getGlobalIPv4(ctx context.Context) (net.IP, error) {
 	if err != nil || ip.To4() == nil {
 		return nil, fmt.Errorf("cannot find public ipv4 address: %w", err)
 	}
+
 	return ip, nil
 }
 
@@ -29,6 +30,7 @@ func getGlobalIPv6(ctx context.Context) (net.IP, error) {
 	if err != nil || ip.To4() != nil {
 		return nil, fmt.Errorf("cannot find public ipv6 address: %w", err)
 	}
+
 	return ip, nil
 }
 
@@ -54,14 +56,17 @@ func fetchIP(ctx context.Context, network string) (net.IP, error) {
 		if resp != nil {
 			io.Copy(ioutil.Discard, resp.Body) // nolint: errcheck
 		}
+
 		return nil, fmt.Errorf("cannot perform a request: %w", err)
 	}
+
 	defer resp.Body.Close() // nolint: errcheck
 
 	respDataBytes, err := ioutil.ReadAll(resp.Body)
 	if err != nil {
 		return nil, fmt.Errorf("cannot read response body: %w", err)
 	}
+
 	respData := strings.TrimSpace(string(respDataBytes))
 
 	ip := net.ParseIP(respData)

config/urls.go

@@ -22,6 +22,7 @@ type IPURLs struct {
 
 func GetURLs() (urls IPURLs) {
 	secret := ""
+
 	switch C.SecretMode {
 	case SecretModeSimple:
 		secret = hex.EncodeToString(C.Secret)

conntypes/protocol.go

@@ -9,6 +9,7 @@ func (c ConnectionProtocol) String() string {
 	case ConnectionProtocolIPv4:
 		return "ipv4"
 	}
+
 	return "ipv6"
 }
 

conntypes/wrappers.go

@@ -1,2 +0,0 @@
-package conntypes
-

hub/connection.go

@@ -47,6 +47,7 @@ func (c *connection) write(packet conntypes.Packet) error {
 		c.pending = 0
 		c.mutex.Unlock()
 	}
+
 	return err
 }
 
@@ -89,6 +90,7 @@ func (c *connection) run() {
 			logger.Debugw("Failed response", "error", err)
 			continue
 		}
+
 		if response.Type == rpc.ProxyResponseTypeCloseExt {
 			logger.Debugw("Proxy has closed connection")
 			return

hub/connection_hub.go

@@ -50,11 +50,11 @@ func (c *connectionHub) runGC() {
 		case conn.closed():
 			logger.Debugw("Delete closed socket", "key", key)
 			delete(c.sockets, key)
-
 		case conn.idle():
 			logger.Debugw("Delete idle socket", "key", key)
 			conn.shutdown()
 			delete(c.sockets, key)
+
 			return
 		}
 	}
@@ -65,12 +65,14 @@ func (c *connectionHub) runConnectionRequest(req *connectionHubRequest) {
 
 	for key, conn := range c.sockets {
 		delete(c.sockets, key)
+
 		if !conn.closed() {
 			logger.Debugw("Choose connection",
 				"id", conn.id,
 				"remote_addr", conn.conn.RemoteAddr())
 			req.response <- conn
 			close(req.response)
+
 			return
 		}
 	}
@@ -81,6 +83,7 @@ func (c *connectionHub) runConnectionRequest(req *connectionHubRequest) {
 			"remote_addr", conn.conn.RemoteAddr())
 		req.response <- conn
 	}
+
 	close(req.response)
 }
 
@@ -93,6 +96,7 @@ func (c *connectionHub) runReturnConnection(conn *connection) {
 	c.logger.Named("return-connection").Debugw("Return connection",
 		"id", conn.id,
 		"remote_addr", conn.conn.RemoteAddr())
+
 	c.sockets[conn.id] = conn
 }
 

hub/ctx_channel.go

@@ -46,11 +46,13 @@ func (c *ctxChannel) sendBack(response *rpc.ProxyResponse) error {
 func (c *ctxChannel) Close() error {
 	c.cancel()
 	c.channel = nil
+
 	return nil
 }
 
 func newCtxChannel(ctx context.Context) *ctxChannel {
 	ctx, cancel := context.WithCancel(ctx)
+
 	return &ctxChannel{
 		channel: make(chan *rpc.ProxyResponse),
 		ctx:     ctx,

hub/hub.go

@@ -42,9 +42,9 @@ func (h *hub) Write(packet conntypes.Packet, req *protocol.TelegramRequest) erro
 
 func (h *hub) getHub(req *protocol.TelegramRequest) *connectionHub {
 	keyBuilder := strings.Builder{}
-	binary.Write(&keyBuilder, binary.LittleEndian, int16(req.ClientProtocol.DC()))
+	binary.Write(&keyBuilder, binary.LittleEndian, int16(req.ClientProtocol.DC())) // nolint: errcheck
 	keyBuilder.WriteRune('_')
-	binary.Write(&keyBuilder, binary.LittleEndian, uint8(req.ClientProtocol.ConnectionProtocol()))
+	binary.Write(&keyBuilder, binary.LittleEndian, uint8(req.ClientProtocol.ConnectionProtocol())) // nolint: errcheck
 	key := keyBuilder.String()
 
 	h.mutex.RLock()
@@ -60,6 +60,7 @@ func (h *hub) getHub(req *protocol.TelegramRequest) *connectionHub {
 			h.logger.Debugw("Create new connection hub",
 				"dc", req.ClientProtocol.DC(),
 				"protocol", req.ClientProtocol.ConnectionProtocol())
+
 			rv = newConnectionHub(h.logger.With(
 				"dc", req.ClientProtocol.DC(),
 				"protocol", req.ClientProtocol.ConnectionProtocol(),

hub/registry.go

@@ -40,5 +40,6 @@ func (r *registry) getChannel(id conntypes.ConnID) (*ctxChannel, bool) {
 	if value, ok := r.conns[string(id[:])]; ok {
 		return value, true
 	}
+
 	return nil, false
 }

main.go

@@ -119,7 +119,6 @@ func main() {
 	switch kingpin.MustParse(app.Parse(os.Args[1:])) {
 	case generateSecretCommand.FullCommand():
 		cli.Generate(*generateSecretType)
-
 	case proxyCommand.FullCommand():
 		err := config.Init(
 			config.Opt{Option: config.OptionTypeDebug, Value: *proxyDebug},

mtproto/protocol.go

@@ -20,6 +20,7 @@ func TelegramProtocol(req *protocol.TelegramRequest) (conntypes.PacketReadWriteC
 
 	rpcNonceConn := packet.NewMtprotoFrame(conn, rpc.SeqNoNonce)
 	rpcNonceReq, err := doRPCNonceRequest(rpcNonceConn)
+
 	if err != nil {
 		return nil, fmt.Errorf("cannot do nonce request: %w", err)
 	}
@@ -35,6 +36,7 @@ func TelegramProtocol(req *protocol.TelegramRequest) (conntypes.PacketReadWriteC
 	if err := doRPCHandshakeRequest(frameConn); err != nil {
 		return nil, fmt.Errorf("cannot do handshake request: %w", err)
 	}
+
 	if err := getRPCHandshakeResponse(frameConn); err != nil {
 		return nil, fmt.Errorf("cannot get handshake response: %w", err)
 	}
@@ -42,11 +44,12 @@ func TelegramProtocol(req *protocol.TelegramRequest) (conntypes.PacketReadWriteC
 	return frameConn, nil
 }
 
-func doRPCNonceRequest(conn conntypes.PacketWriter) (*rpc.NonceRequest, error) {
+func doRPCNonceRequest(conn conntypes.BasePacketWriter) (*rpc.NonceRequest, error) {
 	rpcNonceReq, err := rpc.NewNonceRequest(telegram.Middle.Secret())
 	if err != nil {
 		panic(err)
 	}
+
 	if err := conn.Write(rpcNonceReq.Bytes()); err != nil {
 		return nil, err
 	}
@@ -54,7 +57,7 @@ func doRPCNonceRequest(conn conntypes.PacketWriter) (*rpc.NonceRequest, error) {
 	return rpcNonceReq, nil
 }
 
-func getRPCNonceResponse(conn conntypes.PacketReader, req *rpc.NonceRequest) (*rpc.NonceResponse, error) {
+func getRPCNonceResponse(conn conntypes.BasePacketReader, req *rpc.NonceRequest) (*rpc.NonceResponse, error) {
 	packet, err := conn.Read()
 	if err != nil {
 		return nil, fmt.Errorf("cannot read from connection: %w", err)
@@ -62,8 +65,9 @@ func getRPCNonceResponse(conn conntypes.PacketReader, req *rpc.NonceRequest) (*r
 
 	resp, err := rpc.NewNonceResponse(packet)
 	if err != nil {
-		return nil, fmt.Errorf("cannot build rpc nonce responce: %w", err)
+		return nil, fmt.Errorf("cannot build rpc nonce response: %w", err)
 	}
+
 	if err = resp.Valid(req); err != nil {
 		return nil, fmt.Errorf("invalid nonce response: %w", err)
 	}
@@ -71,14 +75,15 @@ func getRPCNonceResponse(conn conntypes.PacketReader, req *rpc.NonceRequest) (*r
 	return resp, nil
 }
 
-func doRPCHandshakeRequest(conn conntypes.PacketWriter) error {
+func doRPCHandshakeRequest(conn conntypes.BasePacketWriter) error {
 	if err := conn.Write(rpc.HandshakeRequest); err != nil {
 		return fmt.Errorf("cannot make a request: %w", err)
 	}
+
 	return nil
 }
 
-func getRPCHandshakeResponse(conn conntypes.PacketReader) error {
+func getRPCHandshakeResponse(conn conntypes.BasePacketReader) error {
 	packet, err := conn.Read()
 	if err != nil {
 		return fmt.Errorf("cannot read a response: %w", err)
@@ -88,6 +93,7 @@ func getRPCHandshakeResponse(conn conntypes.PacketReader) error {
 	if err != nil {
 		return fmt.Errorf("cannot build a handshake response: %w", err)
 	}
+
 	if err := resp.Valid(); err != nil {
 		return fmt.Errorf("invalid handshake response: %w", err)
 	}

mtproto/rpc/handshake_response.go

@@ -28,10 +28,11 @@ func (r *HandshakeResponse) Bytes() []byte {
 // Valid checks that handshake response compliments request.
 func (r *HandshakeResponse) Valid() error {
 	if !bytes.Equal(r.Type, TagHandshake) {
-		return errors.New("Unexpected handshake tag")
+		return errors.New("unexpected handshake tag")
 	}
+
 	if !bytes.Equal(r.PeerPID, HandshakeSenderPID) {
-		return errors.New("Incorrect sender PID")
+		return errors.New("incorrect sender PID")
 	}
 
 	return nil
@@ -41,7 +42,7 @@ func (r *HandshakeResponse) Valid() error {
 // data.
 func NewHandshakeResponse(data []byte) (*HandshakeResponse, error) {
 	if len(data) != 32 {
-		return nil, fmt.Errorf("Incorrect handshake response length %d", len(data))
+		return nil, fmt.Errorf("incorrect handshake response length %d", len(data))
 	}
 
 	return &HandshakeResponse{

mtproto/rpc/nonce_request.go

@@ -36,6 +36,7 @@ func NewNonceRequest(proxySecret []byte) (*NonceRequest, error) {
 	if _, err := rand.Read(nonce); err != nil {
 		return nil, fmt.Errorf("cannot generate nonce: %w", err)
 	}
+
 	copy(keySelector, proxySecret)
 
 	timestamp := time.Now().Truncate(time.Second).Unix() % 4294967296 // 256 ^ 4 - do not know how to name

mtproto/rpc/nonce_response.go

@@ -28,13 +28,15 @@ func (r *NonceResponse) Bytes() []byte {
 
 func (r *NonceResponse) Valid(req *NonceRequest) error {
 	if !bytes.Equal(r.Type, TagNonce) {
-		return errors.New("Unexpected RPC type")
+		return errors.New("unexpected RPC type")
 	}
+
 	if !bytes.Equal(r.Crypto, NonceCryptoAES) {
-		return errors.New("Unexpected crypto type")
+		return errors.New("unexpected crypto type")
 	}
+
 	if !bytes.Equal(r.KeySelector, req.KeySelector) {
-		return errors.New("Unexpected key selector")
+		return errors.New("unexpected key selector")
 	}
 
 	return nil
@@ -43,7 +45,7 @@ func (r *NonceResponse) Valid(req *NonceRequest) error {
 // NewNonceResponse build new nonce response based on the given data.
 func NewNonceResponse(data []byte) (*NonceResponse, error) {
 	if len(data) != 32 {
-		return nil, fmt.Errorf("Unexpected message length %d", len(data))
+		return nil, fmt.Errorf("unexpected message length %d", len(data))
 	}
 
 	return &NonceResponse{

mtproto/rpc/proxy_flags.go

@@ -33,24 +33,31 @@ func (r ProxyRequestFlags) String() string {
 	if r&ProxyRequestFlagsHasAdTag != 0 {
 		flags = append(flags, "HAS_AD_TAG")
 	}
+
 	if r&ProxyRequestFlagsEncrypted != 0 {
 		flags = append(flags, "ENCRYPTED")
 	}
+
 	if r&ProxyRequestFlagsMagic != 0 {
 		flags = append(flags, "MAGIC")
 	}
+
 	if r&ProxyRequestFlagsExtMode2 != 0 {
 		flags = append(flags, "EXT_MODE_2")
 	}
+
 	if r&ProxyRequestFlagsIntermediate != 0 {
 		flags = append(flags, "INTERMEDIATE")
 	}
+
 	if r&ProxyRequestFlagsAbdridged != 0 {
 		flags = append(flags, "ABRIDGED")
 	}
+
 	if r&ProxyRequestFlagsQuickAck != 0 {
 		flags = append(flags, "QUICK_ACK")
 	}
+
 	if r&ProxyRequestFlagsPad != 0 {
 		flags = append(flags, "PAD")
 	}

mtproto/rpc/proxy_response.go

@@ -29,21 +29,23 @@ func ParseProxyResponse(packet conntypes.Packet) (*ProxyResponse, error) {
 	}
 
 	tag := packet[:4]
+
 	switch {
 	case bytes.Equal(tag, TagProxyAns):
 		response.Type = ProxyResponseTypeAns
 		copy(response.ConnID[:], packet[8:16])
 		response.Payload = packet[16:]
-		return &response, nil
 
+		return &response, nil
 	case bytes.Equal(tag, TagSimpleAck):
 		response.Type = ProxyResponseTypeSimpleAck
 		copy(response.ConnID[:], packet[4:12])
 		response.Payload = packet[12:]
-		return &response, nil
 
+		return &response, nil
 	case bytes.Equal(tag, TagCloseExt):
 		response.Type = ProxyResponseTypeCloseExt
+
 		return &response, nil
 	}
 

ntp/ntp.go

@@ -21,15 +21,17 @@ var ntpEndpoints = [...]string{
 // Fetch fetches the data on time drift.
 func Fetch() (time.Duration, error) {
 	url := ntpEndpoints[rand.Intn(len(ntpEndpoints))]
+
 	resp, err := ntp.Query(url)
 	if err != nil {
-		return 0, fmt.Errorf("Cannot fetch NTP server %s: %w", url, err)
+		return 0, fmt.Errorf("cannot fetch NTP server %s: %w", url, err)
 	}
 
 	offsetInt := int64(resp.ClockOffset)
 	if offsetInt < 0 {
 		offsetInt = -offsetInt
 	}
+
 	offset := time.Duration(offsetInt)
 
 	return offset, nil

obfuscated2/client_protocol.go

@@ -58,6 +58,7 @@ func (c *ClientProtocol) Handshake(socket conntypes.StreamReadWriteCloser) (conn
 	decryptor.XORKeyStream(decryptedFrame.Bytes(), fm.Bytes())
 
 	magic := decryptedFrame.Magic()
+
 	switch {
 	case bytes.Equal(magic, conntypes.ConnectionTagAbridged):
 		c.connectionType = conntypes.ConnectionTypeAbridged
@@ -66,7 +67,7 @@ func (c *ClientProtocol) Handshake(socket conntypes.StreamReadWriteCloser) (conn
 	case bytes.Equal(magic, conntypes.ConnectionTagSecure):
 		c.connectionType = conntypes.ConnectionTypeSecure
 	default:
-		return nil, errors.New("Unknown connection type")
+		return nil, errors.New("unknown connection type")
 	}
 
 	c.connectionProtocol = conntypes.ConnectionProtocolIPv4
@@ -81,8 +82,9 @@ func (c *ClientProtocol) Handshake(socket conntypes.StreamReadWriteCloser) (conn
 
 	antiReplayKey := decryptedFrame.Unique()
 	if antireplay.Cache.Has(antiReplayKey) {
-		return nil, errors.New("Replay attack is detected")
+		return nil, errors.New("replay attack is detected")
 	}
+
 	antireplay.Cache.Add(antiReplayKey)
 
 	return stream.NewObfuscated2(socket, encryptor, decryptor), nil
@@ -92,6 +94,7 @@ func (c *ClientProtocol) ReadFrame(socket conntypes.StreamReader) (fm Frame, err
 	if _, err = io.ReadFull(handshakeReader{socket}, fm.Bytes()); err != nil {
 		err = fmt.Errorf("cannot extract obfuscated2 frame: %w", err)
 	}
+
 	return
 }
 

obfuscated2/telegram_protocol.go

@@ -17,6 +17,7 @@ func TelegramProtocol(req *protocol.TelegramRequest) (conntypes.StreamReadWriteC
 	if err != nil {
 		return nil, fmt.Errorf("cannot dial to telegram: %w", err)
 	}
+
 	conn = stream.NewTimeout(conn)
 	conn = stream.NewCtx(req.Ctx, req.Cancel, conn)
 	fm := generateFrame(req.ClientProtocol)
@@ -45,6 +46,7 @@ func generateFrame(cp protocol.ClientProtocol) (fm Frame) {
 		if _, err := rand.Read(data); err != nil {
 			continue
 		}
+
 		if data[0] == 0xef {
 			continue
 		}

proxy/direct.go

@@ -18,13 +18,16 @@ func directConnection(request *protocol.TelegramRequest) error {
 	if err != nil {
 		return err
 	}
+
 	telegramConn := telegramConnRaw.(conntypes.StreamReadWriteCloser)
+
 	defer telegramConn.Close()
 
 	wg := &sync.WaitGroup{}
 	wg.Add(2)
 
 	go directPipe(telegramConn, request.ClientConn, wg, request.Logger)
+
 	go directPipe(request.ClientConn, telegramConn, wg, request.Logger)
 
 	wg.Wait()

proxy/middle.go

@@ -10,11 +10,12 @@ import (
 	"github.com/9seconds/mtg/wrappers/packetack"
 )
 
-func middleConnection(request *protocol.TelegramRequest) error {
+func middleConnection(request *protocol.TelegramRequest) {
 	telegramConn := packetack.NewProxy(request)
 	defer telegramConn.Close()
 
 	var clientConn conntypes.PacketAckFullReadWriteCloser
+
 	switch request.ClientProtocol.ConnectionType() {
 	case conntypes.ConnectionTypeAbridged:
 		clientConn = packetack.NewClientAbridged(request.ClientConn)
@@ -30,11 +31,10 @@ func middleConnection(request *protocol.TelegramRequest) error {
 	wg.Add(2)
 
 	go middlePipe(telegramConn, clientConn, wg, request.Logger)
+
 	go middlePipe(clientConn, telegramConn, wg, request.Logger)
 
 	wg.Wait()
-
-	return nil
 }
 
 func middlePipe(dst conntypes.PacketAckWriteCloser,
@@ -50,6 +50,7 @@ func middlePipe(dst conntypes.PacketAckWriteCloser,
 	for {
 		acks := conntypes.ConnectionAcks{}
 		packet, err := src.Read(&acks)
+
 		if err != nil {
 			logger.Debugw("Cannot read packet", "error", err)
 			return

proxy/proxy.go

@@ -34,6 +34,7 @@ func (p *Proxy) Serve(listener net.Listener) {
 				continue
 			}
 		}
+
 		go p.accept(conn)
 	}
 }
@@ -61,10 +62,12 @@ func (p *Proxy) accept(conn net.Conn) {
 	clientConn := stream.NewClientConn(conn, connID)
 	clientConn = stream.NewCtx(ctx, cancel, clientConn)
 	clientConn = stream.NewTimeout(clientConn)
+
 	defer clientConn.Close()
 
 	clientProtocol := p.ClientProtocolMaker()
 	clientConn, err := clientProtocol.Handshake(clientConn)
+
 	if err != nil {
 		logger.Warnw("Cannot perform client handshake", "error", err)
 		return
@@ -83,8 +86,10 @@ func (p *Proxy) accept(conn net.Conn) {
 		ClientProtocol: clientProtocol,
 	}
 
+	err = nil
+
 	if len(config.C.AdTag) > 0 {
-		err = middleConnection(req)
+		middleConnection(req)
 	} else {
 		err = directConnection(req)
 	}

stats/stats.go

@@ -20,11 +20,13 @@ func Init(ctx context.Context) error {
 	}
 
 	stats := []Interface{instancePrometheus}
+
 	if config.C.StatsdAddr != nil {
 		instanceStatsd, err := newStatsStatsd()
 		if err != nil {
 			return fmt.Errorf("cannot inialize statsd: %w", err)
 		}
+
 		stats = append(stats, instanceStatsd)
 	}
 
@@ -36,7 +38,9 @@ func Init(ctx context.Context) error {
 	srv := http.Server{
 		Handler: mux,
 	}
+
 	go srv.Serve(listener) // nolint: errcheck
+
 	go func() {
 		<-ctx.Done()
 		srv.Shutdown(context.Background()) // nolint: errcheck

stats/stats_prometheus.go

@@ -122,15 +122,19 @@ func newStatsPrometheus(mux *http.ServeMux) (Interface, error) {
 	if err := registry.Register(instance.connections); err != nil {
 		return nil, fmt.Errorf("cannot register metrics for connections: %w", err)
 	}
+
 	if err := registry.Register(instance.telegramConnections); err != nil {
 		return nil, fmt.Errorf("cannot register metrics for telegram connections: %w", err)
 	}
+
 	if err := registry.Register(instance.traffic); err != nil {
 		return nil, fmt.Errorf("cannot register metrics for traffic: %w", err)
 	}
+
 	if err := registry.Register(instance.crashes); err != nil {
 		return nil, fmt.Errorf("cannot register metrics for crashes: %w", err)
 	}
+
 	if err := registry.Register(instance.antiReplays); err != nil {
 		return nil, fmt.Errorf("cannot register metrics for anti replays: %w", err)
 	}

stats/stats_statsd.go

@@ -96,6 +96,7 @@ func newStatsStatsd() (Interface, error) {
 		for k, v := range config.C.StatsdTags {
 			tags = append(tags, k, v)
 		}
+
 		options = append(options, statsd.Tags(tags...))
 	}
 

telegram/api/addresses.go

@@ -31,34 +31,36 @@ func getAddresses(url string) (map[conntypes.DC][]string, conntypes.DC, error) {
 	if err != nil {
 		return nil, 0, fmt.Errorf("cannot get http response: %w", err)
 	}
+
 	defer resp.Close()
 
 	scanner := bufio.NewScanner(resp)
 	data := map[conntypes.DC][]string{}
+	defaultDC := conntypes.DCDefaultIdx
 
-	var defaultDC = conntypes.DCDefaultIdx
 	for scanner.Scan() {
 		text := strings.TrimSpace(scanner.Text())
+
 		switch {
 		case strings.HasPrefix(text, "#"):
 			continue
-
 		case strings.HasPrefix(text, "proxy_for"):
 			addr, idx, err := addressesParseProxyFor(text)
 			if err != nil {
 				return nil, 0, fmt.Errorf("cannot parse 'proxy_for' section: %w", err)
 			}
+
 			if addresses, ok := data[idx]; ok {
 				data[idx] = append(addresses, addr)
 			} else {
 				data[idx] = []string{addr}
 			}
-
 		case strings.HasPrefix(text, "default"):
 			idx, err := addressesParseDefault(text)
 			if err != nil {
 				return nil, 0, fmt.Errorf("cannot parse 'default' section: %w", err)
 			}
+
 			defaultDC = idx
 		}
 	}
@@ -97,6 +99,7 @@ func addressesParseDefault(text string) (conntypes.DC, error) {
 	}
 
 	dcString := strings.TrimRight(chunks[1], ";")
+
 	dc, err := strconv.ParseInt(dcString, 10, 16)
 	if err != nil {
 		return 0, fmt.Errorf("incorrect config '%s': %w", text, err)

telegram/api/api.go

@@ -22,15 +22,17 @@ func request(url string) (io.ReadCloser, error) {
 	if err != nil {
 		panic(err)
 	}
+
 	req.Header.Set("Accept", "text/plan")
 	req.Header.Set("User-Agent", apiUserAgent)
 
 	resp, err := httpClient.Do(req)
 	if err != nil {
 		if resp != nil {
-			io.Copy(ioutil.Discard, resp.Body)
+			io.Copy(ioutil.Discard, resp.Body) // nolint: errcheck
 			resp.Body.Close()
 		}
+
 		return nil, fmt.Errorf("cannot perform a request: %w", err)
 	}
 

telegram/api/secret.go

@@ -12,6 +12,7 @@ func Secret() ([]byte, error) {
 	if err != nil {
 		return nil, fmt.Errorf("cannot access telegram server: %w", err)
 	}
+
 	defer resp.Close()
 
 	secret, err := ioutil.ReadAll(resp)

telegram/base.go

@@ -51,7 +51,7 @@ func (b *baseTelegram) chooseAddress(addresses map[conntypes.DC][]string,
 	dc, defaultDC conntypes.DC) string {
 	addrs, ok := addresses[dc]
 	if !ok {
-		addrs, _ = addresses[defaultDC]
+		addrs = addresses[defaultDC]
 	}
 
 	switch {

telegram/middle.go

@@ -55,6 +55,7 @@ func (m *middleTelegram) update() error {
 
 func (m *middleTelegram) backgroundUpdate() {
 	logger := zap.S().Named("telegram")
+
 	for range time.Tick(middleTelegramBackgroundUpdateEvery) {
 		if err := m.update(); err != nil {
 			logger.Warnw("Cannot update Telegram proxies", "error", err)

utils/init_tcp.go

@@ -13,9 +13,11 @@ func InitTCP(conn net.Conn) error {
 	if err := tcpConn.SetNoDelay(true); err != nil {
 		return fmt.Errorf("cannot set TCP_NO_DELAY: %w", err)
 	}
+
 	if err := tcpConn.SetReadBuffer(config.C.ReadBuffer); err != nil {
 		return fmt.Errorf("cannot set read buffer size: %w", err)
 	}
+
 	if err := tcpConn.SetWriteBuffer(config.C.WriteBuffer); err != nil {
 		return fmt.Errorf("cannot set write buffer size: %w", err)
 	}

utils/read_full.go

@@ -13,6 +13,7 @@ func ReadFull(src io.Reader) (rv []byte, err error) {
 		if err != nil {
 			return nil, err
 		}
+
 		rv = append(rv, buf[:n]...)
 	}
 

utils/reverse_bytes.go

@@ -4,8 +4,8 @@ package utils
 func ReverseBytes(data []byte) []byte {
 	dataLen := len(data)
 	rv := make([]byte, dataLen)
-
 	rv[dataLen/2] = data[dataLen/2]
+
 	for i := dataLen/2 - 1; i >= 0; i-- {
 		opp := dataLen - i - 1
 		rv[i], rv[opp] = data[opp], data[i]

utils/rlimit.go

@@ -13,6 +13,7 @@ func SetLimits() error {
 	if err := unix.Getrlimit(unix.RLIMIT_NOFILE, &rLimit); err != nil {
 		return fmt.Errorf("cannot get rlimit: %w", err)
 	}
+
 	rLimit.Cur = rLimit.Max
 
 	if err := unix.Setrlimit(unix.RLIMIT_NOFILE, &rLimit); err != nil {

utils/signal_context.go

@@ -14,6 +14,7 @@ func GetSignalContext() context.Context {
 	sigChan := make(chan os.Signal, 1)
 
 	signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)
+
 	go func() {
 		for range sigChan {
 			cancel()

wrappers/packet/mtproto_frame.go

@@ -41,7 +41,7 @@ type wrapperMtprotoFrame struct {
 	writeSeqNo int32
 }
 
-func (w *wrapperMtprotoFrame) Read() (conntypes.Packet, error) {
+func (w *wrapperMtprotoFrame) Read() (conntypes.Packet, error) { // nolint: funlen
 	buf := &bytes.Buffer{}
 	sum := crc32.NewIEEE()
 	writer := io.MultiWriter(buf, sum)
@@ -49,9 +49,11 @@ func (w *wrapperMtprotoFrame) Read() (conntypes.Packet, error) {
 	for {
 		buf.Reset()
 		sum.Reset()
+
 		if _, err := io.CopyN(writer, w.parent, 4); err != nil {
 			return nil, fmt.Errorf("cannot read frame padding: %w", err)
 		}
+
 		if !bytes.Equal(buf.Bytes(), mtprotoFramePadding) {
 			break
 		}
@@ -62,19 +64,23 @@ func (w *wrapperMtprotoFrame) Read() (conntypes.Packet, error) {
 		"messageLength", messageLength,
 		"sequence_number", w.readSeqNo,
 	)
+
 	if messageLength%4 != 0 || messageLength < mtprotoFrameMinMessageLength ||
 		messageLength > mtprotoFrameMaxMessageLength {
-		return nil, fmt.Errorf("Incorrect frame message length %d", messageLength)
+		return nil, fmt.Errorf("incorrect frame message length %d", messageLength)
 	}
 
 	buf.Reset()
 	buf.Grow(int(messageLength) - 4 - 4)
+
 	if _, err := io.CopyN(writer, w.parent, int64(messageLength)-4-4); err != nil {
 		return nil, fmt.Errorf("cannot read the message frame: %w", err)
 	}
 
 	var seqNo int32
-	binary.Read(buf, binary.LittleEndian, &seqNo) // nolint: errcheck, gosec
+
+	binary.Read(buf, binary.LittleEndian, &seqNo) // nolint: errcheck
+
 	if seqNo != w.readSeqNo {
 		return nil, fmt.Errorf("unexpected sequence number %d (wait for %d)", seqNo, w.readSeqNo)
 	}
@@ -110,12 +116,12 @@ func (w *wrapperMtprotoFrame) Write(p conntypes.Packet) error {
 	buf := &bytes.Buffer{}
 	buf.Grow(messageLength + paddingLength)
 
-	binary.Write(buf, binary.LittleEndian, uint32(messageLength))
+	binary.Write(buf, binary.LittleEndian, uint32(messageLength)) // nolint: errcheck
-	binary.Write(buf, binary.LittleEndian, w.writeSeqNo)
+	binary.Write(buf, binary.LittleEndian, w.writeSeqNo)          // nolint: errcheck
 	buf.Write(p)
 
 	checksum := crc32.ChecksumIEEE(buf.Bytes())
-	binary.Write(buf, binary.LittleEndian, checksum)
+	binary.Write(buf, binary.LittleEndian, checksum) // nolint: errcheck
 	buf.Write(bytes.Repeat(mtprotoFramePadding, paddingLength/4))
 
 	w.logger.Debugw("Write MTProto frame",

wrappers/packetack/client_abridged.go

@@ -26,9 +26,11 @@ func (w *wrapperClientAbridged) Read(acks *conntypes.ConnectionAcks) (conntypes.
 	buf := bytes.Buffer{}
 
 	buf.Grow(1)
+
 	if _, err := io.CopyN(&buf, w.parent, 1); err != nil {
 		return nil, fmt.Errorf("cannot read message length: %w", err)
 	}
+
 	msgLength := uint32(buf.Bytes()[0])
 	buf.Reset()
 
@@ -39,17 +41,21 @@ func (w *wrapperClientAbridged) Read(acks *conntypes.ConnectionAcks) (conntypes.
 
 	if msgLength == clientAbridgedSmallPacketLength {
 		buf.Grow(3)
+
 		if _, err := io.CopyN(&buf, w.parent, 3); err != nil {
 			return nil, fmt.Errorf("cannot read correct message length: %w", err)
 		}
+
 		number := utils.Uint24{}
 		copy(number[:], buf.Bytes())
 		msgLength = utils.FromUint24(number)
 	}
+
 	msgLength *= 4
 
 	buf.Reset()
 	buf.Grow(int(msgLength))
+
 	if _, err := io.CopyN(&buf, w.parent, int64(msgLength)); err != nil {
 		return nil, fmt.Errorf("cannot read message: %w", err)
 	}
@@ -66,18 +72,20 @@ func (w *wrapperClientAbridged) Write(packet conntypes.Packet, acks *conntypes.C
 		if _, err := w.parent.Write(utils.ReverseBytes(packet)); err != nil {
 			return fmt.Errorf("cannot send a simpleacked packet: %w", err)
 		}
+
 		return nil
 	}
 
 	packetLength := len(packet) / 4
+
 	switch {
 	case packetLength < clientAbridgedSmallPacketLength:
 		data := append([]byte{byte(packetLength)}, packet...)
 		if _, err := w.parent.Write(data); err != nil {
 			return fmt.Errorf("cannot send small packet: %w", err)
 		}
-		return nil
 
+		return nil
 	case packetLength < clientAbridgedLargePacketLength:
 		length24 := utils.ToUint24(uint32(packetLength))
 		buf := bytes.Buffer{}
@@ -89,6 +97,7 @@ func (w *wrapperClientAbridged) Write(packet conntypes.Packet, acks *conntypes.C
 		if _, err := w.parent.Write(buf.Bytes()); err != nil {
 			return fmt.Errorf("cannot send large packet: %w", err)
 		}
+
 		return nil
 	}
 

wrappers/packetack/client_intermediate.go

@@ -22,9 +22,11 @@ func (w *wrapperClientIntermediate) Read(acks *conntypes.ConnectionAcks) (connty
 	buf := bytes.Buffer{}
 
 	buf.Grow(4)
+
 	if _, err := io.CopyN(&buf, w.parent, 4); err != nil {
 		return nil, fmt.Errorf("cannot read message length: %w", err)
 	}
+
 	length := binary.LittleEndian.Uint32(buf.Bytes())
 
 	if length > clientIntermediateQuickAckLength {
@@ -34,6 +36,7 @@ func (w *wrapperClientIntermediate) Read(acks *conntypes.ConnectionAcks) (connty
 
 	buf.Reset()
 	buf.Grow(int(length))
+
 	if _, err := io.CopyN(&buf, w.parent, int64(length)); err != nil {
 		return nil, fmt.Errorf("cannot read the message: %w", err)
 	}
@@ -46,6 +49,7 @@ func (w *wrapperClientIntermediate) Write(packet conntypes.Packet, acks *conntyp
 		if _, err := w.parent.Write(packet); err != nil {
 			return fmt.Errorf("cannot send simpleacked packet: %w", err)
 		}
+
 		return nil
 	}
 
@@ -55,6 +59,7 @@ func (w *wrapperClientIntermediate) Write(packet conntypes.Packet, acks *conntyp
 	if _, err := w.parent.Write(append(length[:], packet...)); err != nil {
 		return fmt.Errorf("cannot send packet: %w", err)
 	}
+
 	return nil
 }
 

wrappers/packetack/client_intermediate_secure.go

@@ -20,6 +20,7 @@ func (w *wrapperClientIntermediateSecure) Read(acks *conntypes.ConnectionAcks) (
 	if err != nil {
 		return nil, err
 	}
+
 	length := len(data) - (len(data) % 4)
 
 	return data[:length], nil
@@ -30,6 +31,7 @@ func (w *wrapperClientIntermediateSecure) Write(packet conntypes.Packet, acks *c
 		if _, err := w.parent.Write(packet); err != nil {
 			return fmt.Errorf("cannot send simpleacked packet: %w", err)
 		}
+
 		return nil
 	}
 
@@ -37,13 +39,14 @@ func (w *wrapperClientIntermediateSecure) Write(packet conntypes.Packet, acks *c
 	paddingLength := rand.Intn(4)
 	buf.Grow(4 + len(packet) + paddingLength)
 
-	binary.Write(&buf, binary.LittleEndian, uint32(len(packet)+paddingLength))
+	binary.Write(&buf, binary.LittleEndian, uint32(len(packet)+paddingLength)) // nolint: errcheck
 	buf.Write(packet)
 	buf.Write(make([]byte, paddingLength))
 
 	if _, err := w.parent.Write(buf.Bytes()); err != nil {
 		return fmt.Errorf("cannot send packet: %w", err)
 	}
+
 	return nil
 }
 

wrappers/packetack/proxy.go

@@ -15,12 +15,12 @@ import (
 )
 
 type wrapperProxy struct {
-	flags        rpc.ProxyRequestFlags
 	request      *protocol.TelegramRequest
 	clientIPPort []byte
 	ourIPPort    []byte
 	channelRead  hub.ChannelReadCloser
 	closeOnce    sync.Once
+	flags        rpc.ProxyRequestFlags
 }
 
 func (w *wrapperProxy) Write(packet conntypes.Packet, acks *conntypes.ConnectionAcks) error {
@@ -30,6 +30,7 @@ func (w *wrapperProxy) Write(packet conntypes.Packet, acks *conntypes.Connection
 	if acks.Quick {
 		flags |= rpc.ProxyRequestFlagsQuickAck
 	}
+
 	if bytes.HasPrefix(packet, rpc.ProxyRequestFlagsEncryptedPrefix[:]) {
 		flags |= rpc.ProxyRequestFlagsEncrypted
 	}
@@ -67,6 +68,7 @@ func (w *wrapperProxy) Close() error {
 		w.channelRead.Close()
 		hub.Registry.Unregister(w.request.ConnID)
 	})
+
 	return nil
 }
 

wrappers/stream/blockcipher.go

@@ -27,6 +27,7 @@ func (w *wrapperBlockCipher) Write(p []byte) (int, error) {
 	if err != nil {
 		return 0, err
 	}
+
 	return w.parent.Write(encrypted)
 }
 
@@ -35,6 +36,7 @@ func (w *wrapperBlockCipher) WriteTimeout(p []byte, timeout time.Duration) (int,
 	if err != nil {
 		return 0, err
 	}
+
 	return w.parent.WriteTimeout(encrypted, timeout)
 }
 
@@ -49,6 +51,7 @@ func (w *wrapperBlockCipher) Read(p []byte) (int, error) {
 		if err != nil {
 			return 0, fmt.Errorf("cannot read data: %w", err)
 		}
+
 		currentBuffer = append(currentBuffer, rv...)
 	}
 

wrappers/stream/conn.go

@@ -38,6 +38,7 @@ func (w *wrapperConn) WriteTimeout(p []byte, timeout time.Duration) (int, error)
 func (w *wrapperConn) Write(p []byte) (int, error) {
 	n, err := w.parent.Write(p)
 	w.logger.Debugw("write to stream", "bytes", n, "error", err)
+
 	if err != nil {
 		w.Close() // nolint: gosec
 	}
@@ -57,6 +58,7 @@ func (w *wrapperConn) ReadTimeout(p []byte, timeout time.Duration) (int, error)
 func (w *wrapperConn) Read(p []byte) (int, error) {
 	n, err := w.parent.Read(p)
 	w.logger.Debugw("Read from stream", "bytes", n, "error", err)
+
 	if err != nil {
 		w.Close()
 	}

wrappers/stream/mtproto_cipher.go

@@ -4,8 +4,8 @@ import (
 	"bytes"
 	"crypto/aes"
 	"crypto/cipher"
-	"crypto/md5"
+	"crypto/md5"  // nolint: gosec
-	"crypto/sha1"
+	"crypto/sha1" // nolint: gosec
 	"encoding/binary"
 	"net"
 
@@ -61,13 +61,16 @@ func mtprotoDeriveKeys(purpose mtprotoCipherPurpose,
 
 	clientIPv4 := mtprotoEmptyIP[:]
 	serverIPv4 := mtprotoEmptyIP[:]
+
 	if client.IP.To4() != nil {
 		clientIPv4 = utils.ReverseBytes(client.IP.To4())
 		serverIPv4 = utils.ReverseBytes(remote.IP.To4())
 	}
+
 	message.Write(serverIPv4) // nolint: gosec
 
 	var port [2]byte
+
 	binary.LittleEndian.PutUint16(port[:], uint16(client.Port))
 	message.Write(port[:]) // nolint: gosec
 
@@ -90,6 +93,7 @@ func mtprotoDeriveKeys(purpose mtprotoCipherPurpose,
 		message.Write(client.IP.To16()) // nolint: gosec
 		message.Write(remote.IP.To16()) // nolint: gosec
 	}
+
 	message.Write(req.Nonce) // nolint: gosec
 
 	data := message.Bytes()

wrappers/stream/obfuscated2.go

@@ -22,6 +22,7 @@ func (w *wrapperObfuscated2) ReadTimeout(p []byte, timeout time.Duration) (int,
 	if err != nil {
 		return 0, fmt.Errorf("cannot read stream ciphered data: %w", err)
 	}
+
 	w.decryptor.XORKeyStream(p, p[:n])
 
 	return n, nil
@@ -32,6 +33,7 @@ func (w *wrapperObfuscated2) Read(p []byte) (int, error) {
 	if err != nil {
 		return n, err
 	}
+
 	w.decryptor.XORKeyStream(p, p[:n])
 
 	return n, nil

wrappers/stream/stats_telegram.go

@@ -65,6 +65,7 @@ func NewTelegramStats(dc conntypes.DC, parent conntypes.StreamReadWriteCloser) c
 		parent: parent,
 		dc:     dc,
 	}
+
 	stats.Stats.TelegramConnected(dc, parent.RemoteAddr())
 
 	return conn