Python套接字监听

Question

下面提到的所有内容都在使用Python2.7的windows计算机上

你好

我目前正试图在一个套接字上监听远程程序发送的数据。然后将这些数据打印到屏幕上，请求用户输入，然后返回到远程程序。在测试中，我可以让远程程序向我发送一个命令行程序菜单（cmd、ipconfig、whoami、ftp），然后我的程序返回一个数字作为菜单选项的选择。

远程程序接收我的响应并发送所选命令的输出。ipconfig和whoami工作得很好，但是cmd和ftp只返回一次终端的输出。（也就是说，我可以在FTP程序中输入一个命令，然后在我没有回音之前将其发送给远程程序）

我的代码中失败的部分是 if ready[0]:在第一次对话之后，永远不要第二次准备就绪。

我知道远程程序运行正常，因为我可以使用netcat代替我的代码，无限期地操作命令终端。

如何正确实现能够解释这种连接的python套接字侦听器？

我的“程序”整体：

import socket, sys, struct, time, select

host = ''
port = 50000
connectionSevered=0

try:
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
except socket.error:
    print 'Failed to create socket'
    sys.exit()
print '[+] Listening for connections on port '+str(port)+'.'

s.bind((host,port))
s.listen(5)         

def recvall(the_socket,timeout=2):
    global connectionSevered
    data='';          # Data found by recv
    total_data=[];    # Finally list of everything

    s.setblocking(0)  #make socket non blocking
    begin=time.time() #beginning time

    while 1:
        ready = select.select([client], [], [], .2)
        if time.time()-begin > timeout:
            print 'Timeout reached'
            #Leave loop, timer has reached its threshold
            break
        if ready[0]:
            print 'In ready loop!'
            try:
                data = client.recv(4096)    #attempt to fetch data
                if data:
                    begin=time.time()       #reset timeout timer
                    total_data.append(data) 
                    data='';
            except socket.error:
                print '[+] Lost connection to client. Printing buffer...'
                connectionSevered=1   # Let main loop know connection has errored
                pass
        time.sleep(1)
    #join all parts to make final string
    return ''.join(total_data)

client, address = s.accept()
print '[+] Client connected!'

while (connectionSevered==0): # While connection hasn't errored
    print "connectionSevered="+str(connectionSevered) # DEBUG
    recvall(s)
    response = raw_input()                  #take user input
    client.sendto(response)                   #send input
client.close(0)

如果你需要更多的信息，请告诉我，任何帮助将非常感谢，我是非常新的，并渴望学习。

Answer 1

玩了一会儿终于让它在使用Python2.7的本地telnet会话中运行得很好。

它所做的是设置一个线程，当客户端连接侦听客户端内容时运行。

当客户端发送一个返回时（“\r\n”如果您与Linux系统交互，则可能需要更改该值？）消息将打印到服务器，如果服务器端有原始输入，则会将此消息发送到客户端：

import socket
import threading
host = ''
port = 50000
connectionSevered=0

class client(threading.Thread):
    def __init__(self, conn):
        super(client, self).__init__()
        self.conn = conn
        self.data = ""
    def run(self):
        while True:
            self.data = self.data + self.conn.recv(1024)
            if self.data.endswith(u"\r\n"):
                print self.data
                self.data = ""

    def send_msg(self,msg):
        self.conn.send(msg)

    def close(self):
        self.conn.close()

try:
    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    s.bind((host,port))
    s.listen(5)
except socket.error:
    print 'Failed to create socket'
    sys.exit()

print '[+] Listening for connections on port: {0}'.format(port)


conn, address = s.accept()
c = client(conn)
c.start()
print '[+] Client connected: {0}'.format(address[0])
c.send_msg(u"\r\n")
print "connectionSevered:{0}".format(connectionSevered) 
while (connectionSevered==0):
    try:
        response = raw_input()  
        c.send_msg(response + u"\r\n")
    except:
        c.close()

以上答案仅适用于一个连接。我已经通过添加另一个连接线程来更新它。现在可以有多个用户连接。

import socket
import threading
import sys
host = ''
port = 50000

class client(threading.Thread):
    def __init__(self, conn):
        super(client, self).__init__()
        self.conn = conn
        self.data = ""

    def run(self):
        while True:
            self.data = self.data + self.conn.recv(1024)
            if self.data.endswith(u"\r\n"):
                print self.data
                self.data = ""

    def send_msg(self,msg):
        self.conn.send(msg)

    def close(self):
        self.conn.close()

class connectionThread(threading.Thread):
    def __init__(self, host, port):
        super(connectionThread, self).__init__()
        try:
            self.s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
            self.s.bind((host,port))
            self.s.listen(5)
        except socket.error:
            print 'Failed to create socket'
            sys.exit()
        self.clients = []

    def run(self):
        while True:
            conn, address = self.s.accept()
            c = client(conn)
            c.start()
            c.send_msg(u"\r\n")
            self.clients.append(c)
            print '[+] Client connected: {0}'.format(address[0])



def main():
    get_conns = connectionThread(host, port)
    get_conns.start()
    while True:
        try:
            response = raw_input() 
            for c in get_conns.clients:
                c.send_msg(response + u"\r\n")
        except KeyboardInterrupt:
            sys.exit()

if __name__ == '__main__':
    main()

客户端无法看到其他客户端所说的话，来自服务器的消息将发送到所有客户端。我把这留给读者作为练习。

Answer 2

如果您现在在Python 3中仍然想知道sockets，那么下面是使用它们的基本方法：

服务器.py

import time
import socket

# creating a socket object
s = socket.socket(socket.AF_INET,
                  socket.SOCK_STREAM)

# get local Host machine name
host = socket.gethostname() # or just use (host == '')
port = 9999

# bind to pot
s.bind((host, port))

# Que up to 5 requests
s.listen(5)

while True:
    # establish connection
    clientSocket, addr = s.accept()
    print("got a connection from %s" % str(addr))
    currentTime = time.ctime(time.time()) + "\r\n"
    clientSocket.send(currentTime.encode('ascii'))
    clientSocket.close()

客户端.py

import socket

# creates socket object
s = socket.socket(socket.AF_INET,
                  socket.SOCK_STREAM)

host = socket.gethostname() # or just use (host = '')
port = 9999

s.connect((host, port))

tm = s.recv(1024) # msg can only be 1024 bytes long

s.close()
print("the time we got from the server is %s" % tm.decode('ascii'))

先运行server.py，然后运行client.py

这只是接收和发送当前时间。

Python3.4套接字有什么新功能？

Python2.7套接字和Python3.4套接字的一个主要区别是发送消息。必须.encode()（通常使用'ascii'或blank作为参数/参数） 然后使用.decode()

例如，使用.encode()发送，使用.decode()接收。

额外信息：client/server socket tutorial