import socket import os import threading from watchdog.observers import Observer from watchdog.events import FileSystemEventHandler from firegex.nfproxy.internals import get_filter_names import traceback from multiprocessing import Process from firegex.nfproxy import ACCEPT, DROP, REJECT, UNSTABLE_MANGLE from rich.markup import escape from rich import print fake_ip_header = b"FAKE:IP:TCP:HEADERS:" fake_ip_header_len = len(fake_ip_header) class LogLevels: INFO = "INFO" WARNING = "WARNING" ERROR = "ERROR" DEBUG = "DEBUG" def load_level_str(level:str): if level is None: return "" match level: case LogLevels.INFO: return "[chartreuse4 bold]\\[INFO][/]" case LogLevels.WARNING: return "[yellow bold]\\[WARNING][/]" case LogLevels.ERROR: return "[red bold]\\[ERROR][/]" case LogLevels.DEBUG: return "[blue bold]\\[DEBUG][/]" case _: return f"\\[[red bold]{escape(level)}[/]]" def log_print(module:str, *args, level:str = LogLevels.INFO, **kwargs): return print(f"{load_level_str(level)}[deep_pink4 bold]\\[nfproxy][/][medium_orchid3 bold]\\[{escape(module)}][/]", *args, **kwargs) class ProxyFilterHandler(FileSystemEventHandler): def __init__(self, reload_action): super().__init__() self.__reload_action = reload_action def on_modified(self, event): if self.__reload_action is not None: self.__reload_action() return super().on_modified(event) def on_deleted(self, event): if self.__reload_action is not None: self.__reload_action() return super().on_deleted(event) def _forward_and_filter(filter_ctx:dict, source:socket.socket, destination:socket.socket, is_input:bool, is_ipv6:bool, is_tcp:bool, has_to_filter:bool = True): """Forward data from source to destination.""" try: def forward(data:bytes): try: destination.sendall(data) except OSError: return def stop_filter_action(data:bytes): nonlocal has_to_filter has_to_filter = False forward(data) while True: try: data = source.recv(4096) except OSError: return if not data: break if has_to_filter: filter_ctx["__firegex_packet_info"] = { "data": data, "l4_size": len(data), "raw_packet": fake_ip_header+data, "is_input": is_input, "is_ipv6": is_ipv6, "is_tcp": is_tcp } try: exec("firegex.nfproxy.internals.handle_packet(globals())", filter_ctx, filter_ctx) except Exception as e: log_print("packet-handling", f"Error while executing filter: {escape(str(e))}, forwarding normally from now", level=LogLevels.ERROR) traceback.print_exc() stop_filter_action(data) continue finally: if "__firegex_packet_info" in filter_ctx.keys(): del filter_ctx["__firegex_packet_info"] result = filter_ctx.get("__firegex_pyfilter_result", None) if result is not None: del filter_ctx["__firegex_pyfilter_result"] if result is None or not isinstance(result, dict): log_print("filter-parsing", "No result found", level=LogLevels.ERROR) stop_filter_action(data) continue action = result.get("action", None) if action is None or not isinstance(action, int): log_print("filter-parsing", "No action found", level=LogLevels.ERROR) stop_filter_action(data) continue if action == ACCEPT.value: forward(data) continue filter_name = result.get("matched_by", None) if filter_name is None or not isinstance(filter_name, str): log_print("filter-parsing", "No matched_by found", level=LogLevels.ERROR) stop_filter_action(data) continue if action == DROP.value: log_print("drop-action", "Dropping packet can't be simulated, so the connection will be rejected", level=LogLevels.WARNING) action = REJECT.value if action == REJECT.value: log_print("reject-action", f"Rejecting connection caused by {escape(filter_name)} pyfilter") source.close() destination.close() return elif action == UNSTABLE_MANGLE.value: mangled_packet = result.get("mangled_packet", None) if mangled_packet is None or not isinstance(mangled_packet, bytes): log_print("filter-parsing", "No mangled_packet found", level=LogLevels.ERROR) stop_filter_action(data) continue log_print("mangle", f"Mangling packet caused by {escape(filter_name)} pyfilter") log_print("mangle", "In the real execution mangling is not so stable as the simulation does, l4_data can be different by data", level=LogLevels.WARNING) forward(mangled_packet[fake_ip_header_len:]) continue else: log_print("filter-parsing", f"Invalid action {action} found", level=LogLevels.ERROR) stop_filter_action(data) continue forward(data) finally: source.close() destination.close() def _execute_proxy(filter_code:str, target_ip:str, target_port:int, local_ip:str = "127.0.0.1", local_port:int = 7474, ipv6:bool = False): addr_family = socket.AF_INET6 if ipv6 else socket.AF_INET server = socket.socket(addr_family, socket.SOCK_STREAM) server.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) server.bind((local_ip, local_port)) server.listen(5) log_print("listener", f"TCP proxy listening on {escape(local_ip)}:{local_port} and forwarding to -> {escape(target_ip)}:{target_port}") try: while True: client_socket, addr = server.accept() log_print("listener", f"Accepted connection from {escape(addr[0])}:{addr[1]}") try: remote_socket = socket.socket(addr_family, socket.SOCK_STREAM) remote_socket.connect((target_ip, target_port)) except Exception as e: log_print("listener", f"Could not connect to remote {escape(target_ip)}:{target_port}: {escape(str(e))}", level=LogLevels.ERROR) client_socket.close() continue try: filter_ctx = {} exec(filter_code, filter_ctx, filter_ctx) # Start two threads to forward data in both directions. threading.Thread(target=_forward_and_filter, args=(filter_ctx, client_socket, remote_socket, True, ipv6, True, True)).start() threading.Thread(target=_forward_and_filter, args=(filter_ctx, remote_socket, client_socket, False, ipv6, True, True)).start() except Exception as e: log_print("listener", f"Error while compiling filter context: {escape(str(e))}, forwarding normally", level=LogLevels.ERROR) traceback.print_exc() threading.Thread(target=_forward_and_filter, args=(filter_ctx, client_socket, remote_socket, True, ipv6, True, False)).start() threading.Thread(target=_forward_and_filter, args=(filter_ctx, remote_socket, client_socket, False, ipv6, True, False)).start() except KeyboardInterrupt: log_print("listener", "Proxy stopped by user") finally: server.close() def _build_filter(filepath:str, proto:str): if os.path.isfile(filepath) is False: raise Exception(f"Filter file {filepath} not found") with open(filepath, "r") as f: filter_code = f.read() filters = get_filter_names(filter_code, proto) filter_code += ( "\n\n__firegex_pyfilter_enabled = [" + ", ".join([repr(f) for f in filters]) + "]\n" "__firegex_proto = " + repr(proto) + "\n" "import firegex.nfproxy.internals\n" "firegex.nfproxy.internals.compile(globals())\n" ) filter_glob = {} exec(filter_code, filter_glob, filter_glob) # test compilation of filters return filter_code def run_proxy_simulation(filter_file:str, proto:str, target_ip:str, target_port:int, local_ip:str = None, local_port:int = 7474, ipv6:bool = False): if local_ip is None: if ipv6: local_ip = "::1" else: local_ip = "127.0.0.1" if os.path.isfile(filter_file) is False: raise Exception(f"\\[nfproxy]\\[init] Filter file {filter_file} not found") proxy_process:Process|None = None def reload_proxy_proc(): nonlocal proxy_process if proxy_process is not None: proxy_process.terminate() proxy_process.join() proxy_process = None compiled_filter = None try: compiled_filter = _build_filter(filter_file, proto) except Exception: log_print("reloader", f"Failed to build filter {escape(filter_file)}!", level=LogLevels.ERROR) traceback.print_exc() if compiled_filter is not None: proxy_process = Process(target=_execute_proxy, args=(compiled_filter, target_ip, target_port, local_ip, local_port, ipv6)) proxy_process.start() observer = Observer() handler = ProxyFilterHandler(reload_proxy_proc) observer.schedule(handler, os.path.abspath(filter_file), recursive=False) observer.start() reload_proxy_proc() log_print("observer", f"Listening for changes on {escape(os.path.abspath(filter_file))}") try: observer.join() except KeyboardInterrupt: observer.stop()