ebc5d6a3e0
* move shell script to a runCommand * multicast needs special options to run on loopback (nix-build sandbox disables non-local network interfaces)
88 lines
2.3 KiB
Python
88 lines
2.3 KiB
Python
# forge packets for testing liminix and send them via the qemu udp
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# multicast socket interface
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MCAST_GRP = '230.0.0.1'
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MCAST_PORT = 1235
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MULTICAST_TTL = 2
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TIMEOUT = 10 # seconds
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from warnings import filterwarnings
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filterwarnings("ignore")
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import random
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import binascii
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import socket
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import time
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import json
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from builtins import bytes, bytearray
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from scapy.all import Ether, IP, UDP, BOOTP, DHCP, sendp, send, raw
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class JSONEncoderWithBytes(json.JSONEncoder):
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def default(self, obj):
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if isinstance(obj, (bytes, bytearray)):
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return obj.decode('utf-8')
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return json.JSONEncoder.default(self, obj)
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def dhcp_option(pkt, label):
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if pkt.haslayer(DHCP):
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for i in pkt[DHCP].options:
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l, v = i
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if l == label:
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return v
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return None
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def is_dhcp_offer(pkt):
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val = dhcp_option(pkt, 'message-type')
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return (val == 2)
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def mac_to_bytes(mac_addr: str) -> bytes:
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""" Converts a MAC address string to bytes.
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"""
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return int(mac_addr.replace(":", ""), 16).to_bytes(6, "big")
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client_mac = "01:02:03:04:05:06"
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discover = (
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Ether(dst="ff:ff:ff:ff:ff:ff") /
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IP(src="0.0.0.0", dst="255.255.255.255") /
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UDP(sport=68, dport=67) /
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BOOTP(
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chaddr=mac_to_bytes(client_mac),
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xid=random.randint(1, 2**32-1),
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) /
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DHCP(options=[("message-type", "discover"), "end"])
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)
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payload = raw(discover)
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sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
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sock.settimeout(TIMEOUT)
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sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
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sock.setsockopt(socket.IPPROTO_IP, socket.IP_MULTICAST_TTL, MULTICAST_TTL)
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sock.bind((MCAST_GRP, MCAST_PORT))
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sock.setsockopt(socket.SOL_IP, socket.IP_MULTICAST_IF, socket.inet_aton('127.0.0.1'))
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sock.setsockopt(socket.SOL_IP, socket.IP_ADD_MEMBERSHIP,
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socket.inet_aton(MCAST_GRP) + socket.inet_aton('127.0.0.1'))
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endtime = time.time() + TIMEOUT
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sock.sendto(payload, (MCAST_GRP, MCAST_PORT))
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while time.time() < endtime:
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try:
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data, addr = sock.recvfrom(1024)
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except socket.error as e:
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print('recv exception: ', e)
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else:
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reply = Ether(data)
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if is_dhcp_offer(reply):
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opts = dict([o for o in reply[DHCP].options if type(o) is tuple])
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print(json.dumps(opts, cls=JSONEncoderWithBytes))
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exit(0)
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exit(1)
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