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Updating arp responder.py to capture and use vlan from packet #1201

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Merged
prsunny merged 2 commits into from
Nov 22, 2019
Merged

Updating arp responder.py to capture and use vlan from packet #1201

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53e6f48
Updating arp responder.py to capture and use vlan from packet
Oct 17, 2019
40447b8
Fixing overriding python dictionary when multiple iface@vlan are present
Nov 22, 2019
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54 changes: 37 additions & 17 deletions ansible/roles/test/files/helpers/arp_responder.py
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Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,12 @@
import os.path
from fcntl import ioctl
from pprint import pprint

import logging
logging.getLogger("scapy.runtime").setLevel(logging.ERROR)
import ptf.packet as scapy
import scapy.all as scapy2
scapy2.conf.use_pcap=True
import scapy.arch.pcapdnet

def hexdump(data):
print " ".join("%02x" % ord(d) for d in data)
Expand Down Expand Up @@ -39,18 +44,20 @@ def __del__(self):
self.socket.close()

def bind(self):
self.socket = socket.socket(socket.AF_PACKET, socket.SOCK_RAW, socket.htons(self.ETH_P_ALL))
self.socket.bind((self.iface, 0))
self.socket.settimeout(self.RCV_TIMEOUT)
self.socket = scapy2.conf.L2listen(iface=self.iface)

def handler(self):
return self.socket.fileno()
return self.socket

def recv(self):
return self.socket.recv(self.RCV_SIZE)
sniffed = self.socket.recv()
pkt = sniffed[0]
str_pkt = str(pkt).encode("HEX")
binpkt = binascii.unhexlify(str_pkt)
return binpkt

def send(self, data):
self.socket.send(data)
scapy2.sendp(data, iface=self.iface)

def mac(self):
return self.mac_address
Expand All @@ -75,7 +82,7 @@ def poll(self):


class ARPResponder(object):
ARP_PKT_LEN = 60
ARP_PKT_LEN = 64
ARP_OP_REQUEST = 1
def __init__(self, ip_sets):
self.arp_chunk = binascii.unhexlify('08060001080006040002') # defines a part of the packet for ARP Reply
Expand All @@ -90,7 +97,7 @@ def action(self, interface):
if len(data) > self.ARP_PKT_LEN:
return

remote_mac, remote_ip, request_ip, op_type = self.extract_arp_info(data)
remote_mac, remote_ip, request_ip, op_type, vlan_id = self.extract_arp_info(data)

# Don't send ARP response if the ARP op code is not request
if op_type != self.ARP_OP_REQUEST:
Expand All @@ -99,20 +106,32 @@ def action(self, interface):
request_ip_str = socket.inet_ntoa(request_ip)
if request_ip_str not in self.ip_sets[interface.name()]:
return

if 'vlan' in self.ip_sets[interface.name()]:
vlan_id = self.ip_sets[interface.name()]['vlan']
else:
vlan_id = None

arp_reply = self.generate_arp_reply(self.ip_sets[interface.name()][request_ip_str], remote_mac, request_ip, remote_ip, vlan_id)
interface.send(arp_reply)

return

def extract_arp_info(self, data):
# remote_mac, remote_ip, request_ip, op_type
return data[6:12], data[28:32], data[38:42], (ord(data[20]) * 256 + ord(data[21]))
rem_ip_start = 28
req_ip_start = 38
op_type_start = 20
eth_offset = 0
vlan_id = None
ether_type = str(data[12:14]).encode("HEX")
if (ether_type == '8100'):
vlan = str(data[14:16]).encode("HEX")
if (vlan != '0000'):
eth_offset = 4
vlan_id = data[14:16]
rem_ip_start = rem_ip_start + eth_offset
req_ip_start = req_ip_start + eth_offset
op_type_start = op_type_start + eth_offset
rem_ip_end = rem_ip_start + 4
req_ip_end = req_ip_start + 4
op_type_end = op_type_start + 1

return data[6:12], data[rem_ip_start:rem_ip_end], data[req_ip_start:req_ip_end], (ord(data[op_type_start]) * 256 + ord(data[op_type_end])), vlan_id

def generate_arp_reply(self, local_mac, remote_mac, local_ip, remote_ip, vlan_id):
eth_hdr = remote_mac + local_mac
Expand Down Expand Up @@ -149,7 +168,8 @@ def main():
iface, vlan = iface.split('@')
vlan_tag = format(int(vlan), 'x')
vlan_tag = vlan_tag.zfill(4)
ip_sets[str(iface)] = {}
if str(iface) not in ip_sets:
ip_sets[str(iface)] = {}
if args.extended:
for ip, mac in ip_dict.items():
ip_sets[str(iface)][str(ip)] = binascii.unhexlify(str(mac))
Expand Down