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#!/bin/env python3
import argparse
import re
import socket
import _thread
class ClientState:
CLIENT_IS_SENDING_DOWNSTREAM = 1
CLIENT_IS_SENDING_UPSTREAM = 2
CLIENT_IS_CONNECTING = 3
CLIENT_IS_TERMINATING = 4
def client_main (source, params):
pattern = re.compile(params.regex)
state = ClientState.CLIENT_IS_CONNECTING
t_connect = None
f_connect = None
current_target = None
try:
while True:
if (state == ClientState.CLIENT_IS_SENDING_DOWNSTREAM):
try:
in_data = b""
while True:
in_char = source.recv(1)
in_data = (in_data + in_char)
if (in_char == b"\n"):
break
elif (in_char == b''):
raise Exception("Disconnected client")
up_data = in_data.decode("UTF-8")
valid = 1
except UnicodeDecodeError:
valid = 0
if ((valid == 1) and pattern.match(up_data)):
if (t_connect != None):
if (params.replacement != None):
print("Transformed \"" + up_data + "\"")
up_data = re.sub(
pattern,
params.replacement,
up_data
)
print("into \"" + up_data + "\"")
t_connect.sendall(up_data.encode("UTF-8"))
else:
t_connect.sendall(in_data)
current_target = 't'
state = ClientState.CLIENT_IS_SENDING_UPSTREAM
print("[Matched] Sending upstream...")
else:
source.send(b"!P \n")
print("Matched")
else:
if (f_connect != None):
f_connect.sendall(in_data)
current_target = 'f'
state = ClientState.CLIENT_IS_SENDING_UPSTREAM
print("[No match] Sending upstream...")
else:
source.sendall(b"!P \n")
print("Did not match")
elif (state == ClientState.CLIENT_IS_SENDING_UPSTREAM):
matched = 0
c = b"\0"
while (c != b"\n"):
if (current_target == 't'):
c = t_connect.recv(1)
else:
c = f_connect.recv(1)
source.send(c)
if ((matched == 0) and (c == b"!")):
matched = 1
elif ((matched == 1) and ((c == b"P") or (c == b"N"))):
matched = 2
elif ((matched == 2) and (c == b" ")):
print("Sending downstream...")
state = ClientState.CLIENT_IS_SENDING_DOWNSTREAM
else:
matched = -1
elif (state == ClientState.CLIENT_IS_CONNECTING):
print("Connecting to downstream...")
if (params.destination_true != None):
t_connect = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
t_connect.connect(params.destination_true)
if (params.destination_false != None):
f_connect = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
f_connect.connect(params.destination_false)
print("Sending downstream...")
state = ClientState.CLIENT_IS_SENDING_DOWNSTREAM
else:
break
except:
print("Closing")
source.close()
if (t_connect != None):
t_connect.close()
if (f_connect != None):
f_connect.close()
################################################################################
## ARGUMENTS HANDLING ##########################################################
################################################################################
parser = argparse.ArgumentParser(
description = (
"Generates a list of instructions to construct the Structural Level."
)
)
parser.add_argument(
'-s',
'--socket-name',
type = str,
required = True,
help = 'Name of the UNIX socket for this filter.'
)
parser.add_argument(
'-t',
'--destination-true',
type = str,
help = 'UNIX socket this filter sends to when a match is found.',
)
parser.add_argument(
'-f',
'--destination-false',
type = str,
help = 'UNIX socket this filter sends to when a match is found.',
)
parser.add_argument(
'-r',
'--regex',
type = str,
required = True,
help = 'The regex to test the message against.',
)
parser.add_argument(
'-x',
'--replacement',
type = str,
required = False,
help = 'The transformation regex to be applied',
)
args = parser.parse_args()
################################################################################
## MAIN ########################################################################
################################################################################
server_socket = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
server_socket.bind(args.socket_name)
server_socket.listen(5)
while True:
(client, client_address) = server_socket.accept()
_thread.start_new_thread(client_main, (client, args))
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