import sys
import socket
import threading
#回复消息，原样返回
def replyMessage(conn):
  while True:
    data = conn.recv(1024)
    conn.send(data)
    if data.decode().lower() == 'bye':
      break
  conn.close()
def main():
  sockScr = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
  sockScr.bind(('', port))
  sockScr.listen(200)
  while True:
    try:
      conn, addr = sockScr.accept()
      #只允许特定主机访问本服务器
      if addr[0] != onlyYou:
        conn.close()
        continue
      #创建并启动线程
      t = threading.Thread(target=replyMessage, args=(conn,))
      t.start()
    except:
      print('error')
if __name__ == '__main__':
  try:
    #获取命令行参数
    port = int(sys.argv[1])
    onlyYou = sys.argv[2]
    main()
  except:
    print('Must give me a number as port')

import sys
import socket
import threading
def middle(conn, addr):
  #面向服务器的Socket
  sockDst = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
  sockDst.connect((ipServer,portServer))
  while True:
    data = conn.recv(1024).decode()
    print('收到客户端消息：'+data)
    if data == '不要发给服务器':
      conn.send('该消息已被代理服务器过滤'.encode())
      print('该消息已过滤')
    elif data.lower() == 'bye':
      print(str(addr)+'客户端关闭连接')
      break
    else:
      sockDst.send(data.encode())
      print('已转发服务器')
      data_fromServer = sockDst.recv(1024).decode()
      print('收到服务器回复的消息：'+data_fromServer)
      if data_fromServer == '不要发给客户端':
        conn.send('该消息已被代理服务器修改'.encode())
        print('消息已被篡改')
      else:
        conn.send(b'Server reply:'+data_fromServer.encode())
        print('已转发服务器消息给客户端')
  conn.close()
  sockDst.close()
def main():
  sockScr = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
  sockScr.bind(('', portScr))
  sockScr.listen(200)
  print('代理已启动')
  while True:
    try:
      conn, addr = sockScr.accept()
      t = threading.Thread(target=middle, args=(conn, addr))
      t.start()
      print('新客户：'+str(addr))
    except:
      pass
if __name__ == '__main__':
  try:
    #(本机IP地址,portScr)<==>(ipServer,portServer)
    #代理服务器监听端口
    portScr = int(sys.argv[1])
    #服务器IP地址与端口号
    ipServer = sys.argv[2]
    portServer = int(sys.argv[3])
    main()
  except:
    print('Sth error')

import sys
import socket
def main():
  sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
  sock.connect((ip, port))
  while True:
    data = input('What do you want to ask:')
    sock.send(data.encode())
    print(sock.recv(1024).decode())
    if data.lower() == 'bye':
      break
  sock.close()
if __name__ == '__main__':
  try:
    #代理服务器的IP地址和端口号
    ip = sys.argv[1]
    port = int(sys.argv[2])
    main()
  except:
    print('Sth error')