--- a/mqtt/packet/connect_payload.go
+++ b/mqtt/packet/connect_payload.go
@@ -1,7 +1,9 @@
 package packet

 import (
+       "bufio"
        "encoding/binary"
+       "io"
        "regexp"

        "github.com/pkg/errors"
@@ -13,17 +15,20 @@ type ConnectPayload struct {

 var clientIDRegex = regexp.MustCompile("^[a-zA-Z0-9-|]*$")

-func ToConnectPayload(bs []byte) (ConnectPayload, error) {
-       if len(bs) < 3 {
-               return ConnectPayload{}, errors.New("payload length is invalid")
+func ToConnectPayload(r *bufio.Reader) (ConnectPayload, error) {
+       lengthBytes := make([]byte, 2)
+       _, err := io.ReadFull(r, lengthBytes)
+       if err != nil {
+               return ConnectPayload{}, err
        }
-       length := binary.BigEndian.Uint16(bs[0:2])
-       var clientID string
-       if len(bs) < 2+int(length) {
-               return ConnectPayload{}, errors.New("specified length is not equals ClientID length")
-       } else {
-               clientID = string(bs[2 : 2+length])
+       length := binary.BigEndian.Uint16(lengthBytes)
+
+       clientIDBytes := make([]byte, length)
+       _, err = io.ReadFull(r, clientIDBytes)
+       if err != nil {
+               return ConnectPayload{}, err
        }
+       clientID := string(clientIDBytes)
        if len(clientID) < 1 || len(clientID) > 23 {
                return ConnectPayload{}, errors.New("ClientID length is invalid")
        }