def udp_listener(dest_ip: str, timeout: float) -> Set[int]:
"""
This listener detects UDP packets from dest_ip in the given timespan,
all ports that send direct replies are marked as being open.
Returns a list of open ports.
"""
time_remaining = timeout
ports: Set[int] = set()
with socket.socket(socket.AF_INET, socket.SOCK_RAW,
socket.IPPROTO_UDP) as s:
while True:
time_taken = ip_utils.wait_for_socket(s, time_remaining)
if time_taken == -1:
break
else:
time_remaining -= time_taken
packet = s.recv(1024)
ip = headers.ip(packet[:20])
udp = headers.udp(packet[20:28])
# unpack the UDP header
if dest_ip == ip.source and ip.protocol == 17:
ports.add(udp.src)
return ports
def ping(ID: int, timeout: float) -> Set[Tuple[str, float, headers.ip]]:
"""
Takes in a process id and a timeout and returns
a list of addresses which sent ICMP ECHO REPLY
packets with the packed id matching ID in the time given by timeout.
"""
ping_sock = socket.socket(socket.AF_INET, socket.SOCK_RAW,
socket.IPPROTO_ICMP)
# opens a raw socket for sending ICMP protocol packets
time_remaining = timeout
addresses = set()
recieved_from = set()
while True:
time_waiting = ip_utils.wait_for_socket(ping_sock, time_remaining)
# time_waiting stores the time the socket took to become readable
# or returns minus one if it ran out of time
if time_waiting == -1:
break
time_recieved = time.time()
# store the time the packet was recieved
recPacket, addr = ping_sock.recvfrom(1024)
# recieve the packet
ip = headers.ip(recPacket[:20])
# unpack the IP header into its respective components
icmp = headers.icmp(recPacket[20:28])
# unpack the time from the packet.
time_sent = struct.unpack("d",
recPacket[28:28 + struct.calcsize("d")])[0]
# unpack the value for when the packet was sent
time_taken: float = time_recieved - time_sent
# calculate the round trip time taken for the packet
if icmp.id == ID:
# if the ping was sent from this machine then add it to the list of
# responses
ip_address, port = addr
# this is to prevent a bug where IPs were being added twice
if ip_address not in recieved_from:
addresses.add((ip_address, time_taken, ip))
recieved_from.add(ip_address)
elif time_remaining <= 0:
break
else:
continue
# return a list of all the addesses that replied to our ICMP echo request.
return addresses
def main() -> None:
# socket object using an IPV4 address, using only raw socket access, set
# ICMP protocol
ping_sock = socket.socket(socket.AF_INET, socket.SOCK_RAW,
socket.IPPROTO_ICMP)
packets: List[bytes] = []
while len(packets) < 1:
recPacket, addr = ping_sock.recvfrom(1024)
ip = headers.ip(recPacket[:20])
icmp = headers.icmp(recPacket[20:28])
print(ip)
print()
print(icmp)
print("\n")
packets.append(recPacket)
def icmp_unreachable(src_ip: str, timeout: float = 2) -> int:
"""
This listener detects ICMP destination unreachable
packets and returns the icmp code.
This is later used to mark them as either close, open|filtered, filtered.
3 -> closed
0|1|2|9|10|13 -> filtered
-1 -> error with arguments
open|filtered means that they are either open or
filtered but return nothing.
"""
ping_sock = socket.socket(socket.AF_INET, socket.SOCK_RAW,
socket.IPPROTO_ICMP)
# open raw socket to listen for ICMP destination unrechable packets
time_remaining = timeout
code = -1
while True:
time_waiting = ip_utils.wait_for_socket(ping_sock, time_remaining)
# wait for socket to be readable
if time_waiting == -1:
break
else:
time_remaining -= time_waiting
recPacket, addr = ping_sock.recvfrom(1024)
# recieve the packet
ip = headers.ip(recPacket[:20])
icmp = headers.icmp(recPacket[20:28])
valid_codes = [0, 1, 2, 3, 9, 10, 13]
if (ip.source == src_ip and icmp.type == 3
and icmp.code in valid_codes):
code = icmp.code
break
elif time_remaining <= 0:
break
else:
continue
ping_sock.close()
return code