利用asyncore.dispatcher写的端口转发器

创建三个继承类，PortForwarder用于监听本地，Receiver与PortForwarder套接字相连，用于接受本地请求，发给数据给远程主机，Sender与Receiver相互包含，用于接受远程主机数据和发送数据到本地。大致形成这样的关系：本地主机---PortForwarder---Receiver---Sender---远程主机

  1 #!/usr/bin/env python
  2 #-*- coding:utf-8 -*-
  3
  4 import argparse
  5 import asyncore
  6 import socket
  7
  8 LOCAL_SERVER_HOST = ‘localhost‘
  9 REMOTE_SERVER_HOST = ‘www.baidu.com‘
 10 BUFSIZE = 4096
 11 LOCAL_SERVER_PORT = 0
 12
 13 class PortForwarder(asyncore.dispatcher):#监听本地
 14     def __init__(self, ip, port, remoteip, remoteport, backlog=5):
 15         asyncore.dispatcher.__init__(self)
 16         self.remoteip = remoteip
 17         self.remoteport = remoteport
 18         self.create_socket(socket.AF_INET, socket.SOCK_STREAM)#创建一个套接字对象
 19         self.set_reuse_addr()#设置地址端口可重用
 20         self.bind((ip, port))#绑定本地ip与端口
 21         self.listen(backlog)#开始监听
 22
 23     def handle_accept(self):#处理接受
 24         conn, addr = self.accept()#等待接受
 25         print "Connected to:", addr
 26         Sender(Receiver(conn), self.remoteip, self.remoteport)
 27
 28 class Receiver(asyncore.dispatcher):#接受本地请求数据，发送给远程主机
 29     def __init__(self, conn):
 30         asyncore.dispatcher.__init__(self, conn)
 31         #self被初始化为该连接客户端socket
 32         #getpeername函数用于获取与某个套接字关联的外地协议地址
 33         self.from_remote_buffer = ‘‘#保存来自远程主机数据
 34         self.to_remote_buffer = ‘‘    #保存本地请求数据
 35         self.sender = None
 36
 37     def handle_connect(self):
 38         pass
 39
 40     def handle_read(self):#接受本地请求
 41         read = self.recv(BUFSIZE)
 42         self.to_remote_buffer += read;
 43         print "receiver read", self.to_remote_buffer
 44
 45     def writable(self):#判断是否有来自远程主机的数据，如果有，调用handle_write
 46         return (len(self.from_remote_buffer) > 0)
 47
 48     def handle_write(self):#发送来自远程主机的数据给本地主机
 49         sent = self.send(self.from_remote_buffer)
 50         print "receiver sent", sent
 51         self.from_remote_buffer = self.from_remote_buffer[sent:]#发送完成后清空数据
 52
 53     def handle_close(self):
 54         self.close()
 55         if self.sender:
 56             self.sender.close()
 57
 58 class Sender(asyncore.dispatcher):#接受远程主机数据，发送本地请求数据
 59     def __init__(self, receiver, remoteaddr, remoteport):
 60         asyncore.dispatcher.__init__(self)
 61         self.receiver = receiver#建立Sender与Receiver之间联系
 62         receiver.sender = self    #建立Sender与Receiver之间联系
 63         self.create_socket(socket.AF_INET, socket.SOCK_STREAM)#创建套接字
 64         self.connect((remoteaddr, remoteport))#连接远程主机
 65
 66     def handle_connect(self):
 67         pass
 68
 69     def handle_read(self):#接受来自远程主机的数据
 70         read = self.recv(BUFSIZE)
 71         self.receiver.from_remote_buffer += read
 72         print "sender read", self.receiver.from_remote_buffer
 73
 74     def writable(self):#判断是否有本地请求要发送，如果有，调用handle_write
 75         if len(self.receiver.to_remote_buffer) > 0:
 76             self.receiver.to_remote_buffer = self.receiver.to_remote_buffer.replace 77                 (LOCAL_SERVER_HOST + ‘:‘ + str(LOCAL_SERVER_PORT), REMOTE_SERVER_HOST)
 78             #修改本地请求数据，将本地主机中host改为远程主机地址
 79         return (len(self.receiver.to_remote_buffer) > 0)
 80
 81     def handle_write(self):#发送本地请求数据
 82         sent = self.send(self.receiver.to_remote_buffer)
 83         print "sender write",sent
 84         self.receiver.to_remote_buffer = self.receiver.to_remote_buffer[sent:]
 85
 86     def handle_close(self):
 87         self.close()
 88         self.receiver.close()
 89
 90 if __name__ == ‘__main__‘:
 91     parser = argparse.ArgumentParser(description="stackless socket server example")
 92     parser.add_argument(‘--localhost‘, action="store", dest="local_host", default=LOCAL_SERVER_HOST)
 93     parser.add_argument(‘--local-port‘, action="store", dest="local_port", type=int, required=True)
 94     parser.add_argument(‘--romote-port‘, action="store", dest="remote_host",default=REMOTE_SERVER_HOST)
 95     parser.add_argument(‘--remot-port‘, action="store", dest="remote_port", type=int, default=80)
 96     given_args = parser.parse_args()
 97     local_host, remote_host = given_args.local_host, given_args.remote_host
 98     local_port, remote_port = given_args.local_port, given_args.remote_port
 99     LOCAL_SERVER_PORT = local_port
100     print "start port forwarding local %s:%s => remote %s:%s" % 101         (local_host, local_port, remote_host, remote_port)
102     PortForwarder(local_host, local_port, remote_host, remote_port)
103     asyncore.loop()