python实现简单的TCP代理服务器

# -*- coding: utf-8 -*-

'''
filename:rtcp.py
@desc:
利用python的socket端口转发，用于远程维护
如果连接不到远程，会sleep 36s，最多尝试200(即两小时)

@usage:
./rtcp.py stream1 stream2
stream为：l:port或c:host:port
l:port表示监听指定的本地端口
c:host:port表示监听远程指定的端口

@author: watercloud, zd, knownsec team
@web: www.knownsec.com, blog.knownsec.com
@date: 2009-7
'''

import socket
import sys
import threading
import time

streams = [None, None] # 存放需要进行数据转发的两个数据流（都是SocketObj对象）
debug = 1 # 调试状态 0 or 1

def _usage():
 print 'Usage: ./rtcp.py stream1 stream2
stream : l:port or c:host:port'

def _get_another_stream(num):
 '''
 从streams获取另外一个流对象，如果当前为空，则等待
 '''
 if num == 0:
 num = 1
 elif num == 1:
 num = 0
 else:
 raise "ERROR"

 while True:
 if streams[num] == 'quit':
 print("can't connect to the target, quit now!")
 sys.exit(1)

 if streams[num] != None:
 return streams[num]
 else:
 time.sleep(1)

def _xstream(num, s1, s2):
 '''
 交换两个流的数据
 num为当前流编号,主要用于调试目的，区分两个回路状态用。
 '''
 try:
 while True:
 #注意，recv函数会阻塞，直到对端完全关闭（close后还需要一定时间才能关闭，最快关闭方法是shutdow）
 buff = s1.recv(1024)
 if debug > 0:
 print num,"recv"
 if len(buff) == 0: #对端关闭连接，读不到数据
 print num,"one closed"
 break
 s2.sendall(buff)
 if debug > 0:
 print num,"sendall"
 except :
 print num,"one connect closed."

 try:
 s1.shutdown(socket.SHUT_RDWR)
 s1.close()
 except:
 pass

 try:
 s2.shutdown(socket.SHUT_RDWR)
 s2.close()
 except:
 pass

 streams[0] = None
 streams[1] = None
 print num, "CLOSED"

def _server(port, num):
 '''
 处理服务情况,num为流编号（第0号还是第1号）
 '''
 srv = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
 srv.bind(('0.0.0.0', port))
 srv.listen(1)
 while True:
 conn, addr = srv.accept()
 print "connected from:", addr
 streams[num] = conn # 放入本端流对象
 s2 = _get_another_stream(num) # 获取另一端流对象
 _xstream(num, conn, s2)

def _connect(host, port, num):
 ''' 处理连接，num为流编号（第0号还是第1号）

 @note: 如果连接不到远程，会sleep 36s，最多尝试200(即两小时)
 '''
 not_connet_time = 0
 wait_time = 36
 try_cnt = 199
 while True:
 if not_connet_time > try_cnt:
 streams[num] = 'quit'
 print('not connected')
 return None

 conn = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
 try:
 conn.connect((host, port))
 except Exception, e:
 print ('can not connect %s:%s!' % (host, port))
 not_connet_time += 1
 time.sleep(wait_time)
 continue

 print "connected to %s:%i" % (host, port)
 streams[num] = conn #放入本端流对象
 s2 = _get_another_stream(num) #获取另一端流对象
 _xstream(num, conn, s2)


if __name__ == '__main__':
 if len(sys.argv) != 3:
 _usage()
 sys.exit(1)
 tlist = [] # 线程列表，最终存放两个线程对象
 targv = [sys.argv[1], sys.argv[2] ]
 for i in [0, 1]:
 s = targv[i] # stream描述 c:ip:port 或 l:port
 sl = s.split(':')
 if len(sl) == 2 and (sl[0] == 'l' or sl[0] == 'L'): # l:port
 t = threading.Thread(target=_server, args=(int(sl[1]), i))
 tlist.append(t)
 elif len(sl) == 3 and (sl[0] == 'c' or sl[0] == 'C'): # c:host:port
 t = threading.Thread(target=_connect, args=(sl[1], int(sl[2]), i))
 tlist.append(t)
 else:
 _usage()
 sys.exit(1)

 for t in tlist:
 t.start()
 for t in tlist:
 t.join()
 sys.exit(0)