Python implements a simple TCP proxy server

This article illustrates the python implementation of a simple TCP proxy server method, to share with you for your reference.

The specific implementation code is as follows:

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

'''
filename:rtcp.py
@desc:
 using python the socket Port forwarding for remote maintenance 
 If you can't connect remotely, yes sleep 36s At most 200( In two hours )

@usage:
./rtcp.py stream1 stream2
stream To: l:port or c:host:port
l:port Represents listening on the specified local port 
c:host:port Represents listening on a remotely specified port 

@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] #  Holds two data streams (both) that require data forwarding SocketObj Object) 
debug = 1 #  Debug state  0 or 1

def _usage():
 print 'Usage: ./rtcp.py stream1 stream2nstream : l:port or c:host:port'

def _get_another_stream(num):
 '''
  from streams Gets another stream object and waits if it is currently empty 
 '''
 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):
 '''
  Exchange data from two streams 
 num Number the current stream , It is mainly used for debugging purposes to distinguish the two loop states. 
 '''
 try:
 while True:
  # Pay attention to, recv The function blocks until the opposite is completely closed ( close After also need some time to close, the fastest way to close is shutdow ) 
  buff = s1.recv(1024)
  if debug > 0:
  print num,"recv"
  if len(buff) == 0: # The opposite end closes the connection and the data cannot be read 
  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):
 '''
  Handling service status ,num Is the stream number (no 0 Size or the first. 1 ) no. 
 '''
 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 #  Place the endstream object 
 s2 = _get_another_stream(num) #  Gets the other end stream object 
 _xstream(num, conn, s2)

def _connect(host, port, num):
 '''  Handle connections, num Is the stream number (no 0 Size or the first. 1 ) no. 

 @note:  If you can't connect remotely, yes sleep 36s At most 200( In two hours )
 '''
 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 # Place the endstream object 
 s2 = _get_another_stream(num) # Gets the other end stream object 
 _xstream(num, conn, s2)


if __name__ == '__main__':
 if len(sys.argv) != 3:
 _usage()
 sys.exit(1)
 tlist = [] #  A list of threads that eventually hold two thread objects 
 targv = [sys.argv[1], sys.argv[2] ]
 for i in [0, 1]:
 s = targv[i] # stream describe  c:ip:port  or  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)

Complete sample code click here (link: http://xiazai.jb51.net/201410/yuanma/python-rtcp-master (jb51.net). Rar).

I hope this article has helped you with your Python programming.