| """
|
| NAT Engine Module for VPN
|
| Implements Network Address Translation
|
| """
|
|
|
| import asyncio
|
| import time
|
| from typing import Dict, Optional, Tuple
|
| from dataclasses import dataclass
|
| import logging
|
| import subprocess
|
|
|
| logger = logging.getLogger(__name__)
|
|
|
| @dataclass
|
| class NATSession:
|
| virtual_ip: str
|
| virtual_port: int
|
| real_ip: str
|
| real_port: int
|
| host_port: int
|
| created_time: float
|
| last_activity: float
|
| bytes_in: int = 0
|
| bytes_out: int = 0
|
|
|
| class NATEngine:
|
| def __init__(self, logger_instance=None):
|
| self.sessions: Dict[str, NATSession] = {}
|
| self.port_mappings: Dict[int, Tuple[str, int]] = {}
|
| self.next_port = 10000
|
| self.cleanup_interval = 300
|
| self._cleanup_task = None
|
| self.logger = logger_instance if logger_instance else logging.getLogger(__name__)
|
|
|
| async def start(self):
|
| """Start the NAT engine"""
|
| self._cleanup_task = asyncio.create_task(self._cleanup_loop())
|
| self.logger.info("NAT engine started")
|
|
|
| async def stop(self):
|
| """Stop the NAT engine"""
|
| if self._cleanup_task:
|
| self._cleanup_task.cancel()
|
| try:
|
| await self._cleanup_task
|
| except asyncio.CancelledError:
|
| pass
|
| self.sessions.clear()
|
| self.port_mappings.clear()
|
| self.logger.info("NAT engine stopped")
|
|
|
| def create_session(self, virtual_ip: str, virtual_port: int,
|
| real_ip: str, real_port: int) -> NATSession:
|
| """Create a new NAT session"""
|
| host_port = self._allocate_port()
|
| session = NATSession(
|
| virtual_ip=virtual_ip,
|
| virtual_port=virtual_port,
|
| real_ip=real_ip,
|
| real_port=real_port,
|
| host_port=host_port,
|
| created_time=time.time(),
|
| last_activity=time.time()
|
| )
|
|
|
| session_key = f"{virtual_ip}:{virtual_port}"
|
| self.sessions[session_key] = session
|
| self.port_mappings[host_port] = (virtual_ip, virtual_port)
|
|
|
| self.logger.debug(f"Created NAT session: {session_key} -> {real_ip}:{real_port}")
|
| return session
|
|
|
| def lookup_session(self, ip: str, port: int) -> Optional[NATSession]:
|
| """Look up a NAT session by real IP and port"""
|
| for session in self.sessions.values():
|
| if session.real_ip == ip and session.real_port == port:
|
| return session
|
| return None
|
|
|
| def get_session_by_virtual(self, ip: str, port: int) -> Optional[NATSession]:
|
| """Get session by virtual IP and port"""
|
| return self.sessions.get(f"{ip}:{port}")
|
|
|
| def remove_session(self, session: NATSession):
|
| """Remove a NAT session"""
|
| session_key = f"{session.virtual_ip}:{session.virtual_port}"
|
| if session_key in self.sessions:
|
| del self.sessions[session_key]
|
| if session.host_port in self.port_mappings:
|
| del self.port_mappings[session.host_port]
|
|
|
| def _allocate_port(self) -> int:
|
| """Allocate a new port for NAT"""
|
| while self.next_port in self.port_mappings:
|
| self.next_port += 1
|
| if self.next_port > 65535:
|
| self.next_port = 10000
|
| return self.next_port
|
|
|
| async def _cleanup_loop(self):
|
| """Periodically clean up expired sessions"""
|
| while True:
|
| try:
|
| await asyncio.sleep(self.cleanup_interval)
|
| current_time = time.time()
|
|
|
| for session_key, session in list(self.sessions.items()):
|
| if current_time - session.last_activity > self.cleanup_interval:
|
| self.remove_session(session)
|
| self.logger.debug(f"Removed expired session: {session_key}")
|
|
|
| except asyncio.CancelledError:
|
| break
|
| except Exception as e:
|
| self.logger.error(f"Error in cleanup loop: {e}")
|
|
|
| def get_stats(self) -> Dict:
|
| """Get NAT engine statistics"""
|
| return {
|
| "active_sessions": len(self.sessions),
|
| "allocated_ports": len(self.port_mappings),
|
| "total_bytes_in": sum(s.bytes_in for s in self.sessions.values()),
|
| "total_bytes_out": sum(s.bytes_out for s in self.sessions.values())
|
| }
|
|
|
|
|
|
|
|
|
| async def setup_nat(self, interface: str):
|
| """Setup NAT configuration"""
|
|
|
|
|
| logger.info(f"NAT configuration ready for interface {interface}")
|
| pass
|
|
|
