Periodic stats report may not correct

[John Chang]

Hi,

I've found a behavior that the reported stats of bytes_out from worker
may not match the actual reading from tun interface.

A simple example is mentioned below:
You can find the TX  reported from occtl is 17672025 (17.7 MB)  which
is match the vpns0 interface.
But the value of tx from the ocserv log is only 1642481 (1.64 MB), it
is ten times less than the reading from vpns0.
Is it normal?

Terminal log:
========================================================================
root at 01:~# occtl show user tester4_55 && ifconfig vpns0 && occtl
disconnect user tester4_55
        ID: 20927
        Username: tester4_55   Groupname: (none)
        State: connected
        Device: vpns0   MTU: 1342
        Remote IP: 11.22.33.44   Location:
        Local Device IP: 10.140.0.2
        IPv4: 192.168.1.237   P-t-P IPv4: 192.168.1.1
        User-Agent: Cisco AnyConnect VPN Agent for Apple iPhone
4.6.00122 / iPhone1
        RX: 245575 (245.6 KB)   TX: 17672025 (17.7 MB)
        Average bandwidth RX: 2.2 KB/sec  TX: 159.2 KB/sec
        DPD: 90   KeepAlive: 32400
        Hostname: iPhone
        Connected at: 2018-02-24 23:34 ( 1m:51s)
        Session: TZT+MM
        TLS ciphersuite: (TLS1.2)-(ECDHE-RSA-SECP521R1)-(AES-128-GCM)
        DTLS cipher: (DTLS0.9)-(RSA)-(AES-128-CBC)-(SHA1)
        CSTP compression: lzs   DTLS compression: lzs

        DNS: 8.8.8.8
                8.8.4.4
        Routes: defaultroute
        Restricted to routes: False

vpns0     Link encap:UNSPEC  HWaddr
00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
          inet addr:192.168.1.1  P-t-P:192.168.1.237  Mask:255.255.255.255
          UP POINTOPOINT RUNNING  MTU:1342  Metric:1
          RX packets:4217 errors:0 dropped:0 overruns:0 frame:0
          TX packets:13238 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:500
          RX bytes:245575 (245.5 KB)  TX bytes:17672025 (17.6 MB)

user 'tester4_55' was disconnected
root at 01:~#


log of ocserv:
========================================================================
ocserv[20927]: worker[tester4_55]: 119.77.131.116 sent periodic stats
(in: 245575, out: 1642481) to sec-mod