Multiple simultaneous network connections - Telnet

问题:

I'm currently writing a telnet server in Python. It's a content server. People would connect to the server via telnet, and be presented with text-only content.

My problem is that the server would obviously need to support more than one simultaneous connection. The current implementation I have now supports only one.

This is the basic, proof-of-concept server I began with (while the program has changed greatly over time, the basic telnet framework hasn't):

import socket, os

class Server:
    def __init__(self):
        self.host, self.port = 'localhost', 50000
        self.socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self.socket.bind((self.host, self.port))

    def send(self, msg):
        if type(msg) == str: self.conn.send(msg + end)
        elif type(msg) == list or tuple: self.conn.send('\n'.join(msg) + end)

    def recv(self):
        self.conn.recv(4096).strip()

    def exit(self):
        self.send('Disconnecting you...'); self.conn.close(); self.run()
        # closing a connection, opening a new one

    # main runtime
    def run(self):
        self.socket.listen(1)
        self.conn, self.addr = self.socket.accept()
        # there would be more activity here
        # i.e.: sending things to the connection we just made


S = Server()
S.run()

Thanks for your help.

回答1:

Implemented in twisted:

from twisted.internet.protocol import Factory, Protocol
from twisted.internet import reactor

class SendContent(Protocol):
    def connectionMade(self):
        self.transport.write(self.factory.text)
        self.transport.loseConnection()

class SendContentFactory(Factory):
    protocol = SendContent
    def __init__(self, text=None):
        if text is None:
            text = """Hello, how are you my friend? Feeling fine? Good!"""
        self.text = text

reactor.listenTCP(50000, SendContentFactory())
reactor.run()

Testing:

$ telnet localhost 50000
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
Hello, how are you my friend? Feeling fine? Good!
Connection closed by foreign host.

Seriously, when it comes to asynchronous network, twisted is the way to go. It handles multiple connections in a single-thread single-process approach.

回答2:

You need some form of asynchronous socket IO. Have a look at this explanation, which discusses the concept in low-level socket terms, and the related examples which are implemented in Python. That should point you in the right direction.

回答3:

Late for the reply, but with the only answers being Twisted or threads (ouch), I wanted to add an answer for MiniBoa.

http://code.google.com/p/miniboa/

Twisted is great, but it's a rather large beast that may not be the best introduction to single-threaded asynchronous Telnet programming. MiniBoa is a lightweight, asynchronous single-threaded Python Telnet implementation originally designed for muds, which suits the OP's question perfectly.

回答4:

For a really easy win implement you solution using SocketServer & the SocketServer.ThreadingMixIn

have a look a this echo server example it looks quite similar to what you're doing anyway: http://www.oreillynet.com/onlamp/blog/2007/12/pymotw_socketserver.html

回答5:

If you're up for a bit of a conceptual challenge, I'd look into using twisted.

Your case should be trivial to implement as a part of twisted. http://twistedmatrix.com/projects/core/documentation/howto/servers.html

回答6:

If you want to do it in pure python (sans-twisted), you need to do some threading. If you havnt seen it before, check out: http://heather.cs.ucdavis.edu/~matloff/Python/PyThreads.pdf

around page 5/6 is an example that is very relevant ;)

回答7:

First, buy Comer's books on TCP/IP programming.

In those books, Comer will provide several alternative algorithms for servers. There are two standard approaches.

• Thread-per-request.

• Process-per-request.

You must pick one of these two and implement that.

In thread-per, each telnet session is a separate thread in your overall application.

In process-per, you fork each telnet session into a separate subprocess.

You'll find that process-per-request is much, much easier to handle in Python, and it generally makes more efficient use of your system.

Thread-per-request is fine for things that come and go quickly (like HTTP requests). Telnet has long-running sessions where the startup cost for a subprocess does not dominate performance.

回答8:

Try MiniBoa server? It has exactly 0 dependencies, no twisted or other stuff needed. MiniBoa is a non-blocking async telnet server, single threaded, exactly what you need.

http://code.google.com/p/miniboa/

回答9:

Use threading and then add the handler into a function. The thread will call every time a request i made:

Look at this

 import socket               # Import socket module
import pygame
import thread
import threading,sys

s = socket.socket()         # Create a socket object
host = socket.gethostname() # Get local machine name
port = 12345                # Reserve a port for your service.
s.bind((host, port))
print ((host, port))
name = ""
users = []

def connection_handler (c, addr):
      print "conn handle"
      a = c.recv (1024)
      if a == "c":
         b = c.recv (1024)
      if a == "o":
         c.send (str(users))
         a = c.recv (1024)
         if a == "c":
            b = c.recv (1024)
      print a,b






s.listen(6)                 # Now wait for client connection.
while True:
   c, addr = s.accept()
   print 'Connect atempt from:', addr[0]
   username = c.recv(1024)
   print "2"
   if username == "END_SERVER_RUBBISH101":
      if addr[0] == "192.168.1.68":
         break
   users.append(username)
   thread.start_new_thread (connection_handler, (c, addr)) #New thread for connection

print 
s.close()