firegex-traffic-viewer/backend/proxy.py

from typing import List, Set
from netfilterqueue import NetfilterQueue
from scapy.all import IP, TCP, UDP
from subprocess import Popen, PIPE
import os, pcre2, traceback
from kthread import KThread

QUEUE_BASE_NUM = 1000

def bind_queues(func, len_list=1):
    if len_list <= 0: raise Exception("len must be >= 1")
    queue_list = []
    starts = QUEUE_BASE_NUM
    end = starts
    
    def func_wrap(pkt):
        pkt_parsed = IP(pkt.get_payload())
        try:
            if pkt_parsed[UDP if UDP in pkt_parsed else TCP].payload: func(pkt, pkt_parsed)
            else: pkt.accept()
        except Exception:
            traceback.print_exc()
            pkt.accept()

    while True:
        if starts >= 65536:
            raise Exception("Netfilter queue is full!")
        try:
            for _ in range(len_list):
                queue_list.append(NetfilterQueue())
                queue_list[-1].bind(end, func_wrap)
                end+=1
            end-=1
            break
        except OSError:
            del queue_list[-1]
            for ele in queue_list:
                ele.unbind()
            queue_list = []
            starts = end = end+1
    return queue_list, (starts, end)

class FilterTypes:
    INPUT = "FIREGEX-INPUT"
    OUTPUT = "FIREGEX-OUTPUT"

class ProtoTypes:
    TCP = "tcp"
    UDP = "udp"

class IPTables:

    @staticmethod
    def command(params):
        if os.geteuid() != 0:
            exit("You need to have root privileges to run this script.\nPlease try again, this time using 'sudo'. Exiting.")
        return Popen(["iptables"]+params, stdout=PIPE, stderr=PIPE).communicate()

    @staticmethod
    def list_filters(param):
        stdout, strerr = IPTables.command(["-L", str(param), "--line-number", "-n"])
        output = [ele.split() for ele in stdout.decode().split("\n")]
        return [{
            "id": ele[0],
            "target": ele[1],
            "prot": ele[2],
            "opt": ele[3],
            "source": ele[4],
            "destination": ele[5],
            "details": " ".join(ele[6:]) if len(ele) >= 7 else "",
        } for ele in output if len(ele) >= 6 and ele[0].isnumeric()]

    @staticmethod
    def delete_command(param, id):
        IPTables.command(["-R", str(param), str(id)])
    
    @staticmethod
    def create_chain(name):
        IPTables.command(["-N", str(name)])

    @staticmethod
    def flush_chain(name):
        IPTables.command(["-F", str(name)])

    @staticmethod
    def add_chain_to_input(name):
        IPTables.command(["-I", "INPUT", "-j", str(name)])

    @staticmethod
    def add_chain_to_output(name):
        IPTables.command(["-I", "OUTPUT", "-j", str(name)])

    @staticmethod
    def add_s_to_c(proto, port, queue_range):
        init, end = queue_range
        if init > end: init, end = end, init
        IPTables.command([
            "-A", FilterTypes.OUTPUT, "-p", str(proto),
            "--sport", str(port), "-j", "NFQUEUE",
            "--queue-num" if init == end else "--queue-balance",
            f"{init}" if init == end else f"{init}:{end}", "--queue-bypass"
        ])

    @staticmethod
    def add_c_to_s(proto, port, queue_range):
        init, end = queue_range
        if init > end: init, end = end, init
        IPTables.command([
            "-A", FilterTypes.INPUT, "-p", str(proto),
            "--dport", str(port), "-j", "NFQUEUE",
            "--queue-num" if init == end else "--queue-balance",
            f"{init}" if init == end else f"{init}:{end}", "--queue-bypass"
        ])

class FiregexFilter():
    def __init__(self, type, number, queue, proto, port):
        self.type = type
        self.id = int(number)
        self.queue = queue
        self.proto = proto
        self.port = int(port)
    def __repr__(self) -> str:
        return f"<FiregexFilter type={self.type} id={self.id} port={self.port} proto={self.proto} queue={self.queue}>"

    def delete(self):
        IPTables.delete_command(self.type, self.id)

class FiregexFilterManager:

    def __init__(self):
        IPTables.create_chain(FilterTypes.INPUT)
        IPTables.create_chain(FilterTypes.OUTPUT)
        input_found = False
        output_found = False
        for filter in IPTables.list_filters("INPUT"):
            if filter["target"] == FilterTypes.INPUT:
                input_found = True
                break
        for filter in IPTables.list_filters("OUTPUT"):
            if filter["target"] == FilterTypes.OUTPUT:
                output_found = True
                break
        if not input_found: IPTables.add_chain_to_input(FilterTypes.INPUT)
        if not output_found: IPTables.add_chain_to_output(FilterTypes.OUTPUT)


    def get(self) -> List[FiregexFilter]:
        res = []
        balanced_mode = pcre2.PCRE2(b"NFQUEUE balance ([0-9]+):([0-9]+)")
        num_mode = pcre2.PCRE2(b"NFQUEUE num ([0-9]+)")
        port_selected = pcre2.PCRE2(b"[sd]pt:([0-9]+)")
        for filter_type in [FilterTypes.INPUT, FilterTypes.OUTPUT]:
            for filter in IPTables.list_filters(filter_type):
                queue_num = None
                balanced = balanced_mode.search(filter["details"].encode())
                numbered = num_mode.search(filter["details"].encode())
                port = port_selected.search(filter["details"].encode())
                if balanced: queue_num = (int(balanced.group(1).decode()), int(balanced.group(2).decode()))
                if numbered: queue_num = (int(numbered.group(1).decode()), int(numbered.group(1).decode()))
                if queue_num and port:
                    res.append(FiregexFilter(
                        type=filter_type,
                        number=filter["id"],
                        queue=queue_num,
                        proto=filter["prot"],
                        port=port.group(1).decode()
                    ))
        return res
    
    def add(self, proto, port, func, n_threads = 1):
        for ele in self.get():
            if int(port) == ele.port: return None
        
        def c_to_s(pkt, data): return func(pkt, data, True)
        def s_to_c(pkt, data): return func(pkt, data, False)

        queues_c_to_s, codes = bind_queues(c_to_s, n_threads)
        IPTables.add_c_to_s(proto, port, codes)
        queues_s_to_c, codes = bind_queues(s_to_c, n_threads)
        IPTables.add_s_to_c(proto, port, codes)
        return queues_c_to_s + queues_s_to_c

    def delete_all(self):
        for filter_type in [FilterTypes.INPUT, FilterTypes.OUTPUT]:
            IPTables.flush_chain(filter_type)
    
    def delete_by_port(self, port):
        for filter in self.get():
            if filter.port == int(port):
                filter.delete()

class Filter:
    def __init__(self, regex, is_case_sensitive=True, is_blacklist=True, c_to_s=False, s_to_c=False, blocked_packets=0, code=None):
        self.regex = regex
        self.is_case_sensitive = is_case_sensitive
        self.is_blacklist = is_blacklist
        if c_to_s == s_to_c: c_to_s = s_to_c = True # (False, False) == (True, True)
        self.c_to_s = c_to_s
        self.s_to_c = s_to_c
        self.blocked = blocked_packets
        self.code = code
        self.compiled_regex = self.compile()
    
    def compile(self):
        if isinstance(self.regex, str): self.regex = self.regex.encode()
        if not isinstance(self.regex, bytes): raise Exception("Invalid Regex Paramether")
        return pcre2.PCRE2(self.regex if self.is_case_sensitive else b"(?i)"+self.regex)

    def check(self, data):
        return True if self.compiled_regex.search(data) else False

class Proxy:
    def __init__(self, public_port = 0, callback_blocked_update=None, filters=None):
        self.manager = FiregexFilterManager()
        self.port = public_port
        self.filters: Set[Filter] = set(filters) if filters else set([])
        self.use_filters = True
        self.callback_blocked_update = callback_blocked_update
        self.threads = []
        self.queue_list = []

    def start(self):
        self.manager.delete_by_port(self.port)

        def regex_filter(pkt, data, by_client):
            packet = bytes(data[TCP if TCP in data else UDP].payload)
            try:
                for filter in self.filters:
                    if (by_client and filter.c_to_s) or (not by_client and filter.s_to_c):
                        match = filter.check(packet)
                        if (filter.is_blacklist and match) or (not filter.is_blacklist and not match):
                            filter.blocked+=1
                            self.callback_blocked_update(filter)
                            pkt.drop()
                            return 
            except IndexError:
                pass
            pkt.accept()

        self.queue_list = self.manager.add(ProtoTypes.TCP, self.port, regex_filter)
        for ele in self.queue_list:
            self.threads.append(KThread(target=ele.run))
            self.threads[-1].daemon = True
            self.threads[-1].start()

    def stop(self):
        self.manager.delete_by_port(self.port)
        for ele in self.threads:
            ele.kill()
            if ele.is_alive():
                print("Not killed succesffully") #TODO
        self.threads = []
        for ele in self.queue_list:
            ele.unbind()
        self.queue_list = []
        

    def restart(self):
        self.stop()
        self.start()