python telnetlib模块:读取和等待响应

时间:2012-11-07 02:08:12

标签: python response wait telnetlib

我在这张海报上遇到了类似的问题:

Python telnetlib: surprising problem

请注意下面的回复和我的回复。

基本上telnetlib在调用任何读取函数时都不会让我读取整个响应。

在while循环中使用select.select([telnetobject],[],[])之后调用telnet.read_very_eager()以确保读取可用时,我唯一能得到的就是几个字符。到目前为止,我能够提出的唯一解决方案是使用time.sleep(),但它太粗糙的解决方案,我正在寻找更适合的东西。任何帮助表示赞赏...

2 个答案:

答案 0 :(得分:0)

我认为我有同样的问题,我希望这些信息会有所帮助。在我的情况下,我连接到Maya中的mel和python端口,所以我不知道这种体验对你和你的情况是否有用。

  • This answer告诉我,我根本不需要Telnet / telnetlib用于我尝试的I / O,并建议asynchat

  • 事实证明,并非服务器端出现的所有输出都可供客户端读取。我不知道这是一件可能发生的事情,直到我使用asynchat作为第二意见,看到我仍然没有收到“print'Complete Command'”的输出,无论我如何发送它。 (我试图写“打印'完整命令'”并读取结果以了解我的上一个命令何时完成。)

我最后调用了mel的警告命令,它确实产生了客户端可读的输出。将无辜数据作为警告发送是非常令人反感的,但幸运的是,这是一个内部工具。

  • telnetlib似乎没有排队写入。因此,我计划背靠背发送两个命令(真正的命令,然后是“命令完成”公告)并不总是有效。因此,如果您确切地知道您想要read_until()的输出,或者您愿意睡觉直到您怀疑输出已完成,那么读取telnetlib输出似乎是可行的。但是asynchat.push()肯定会按预期排队写入。

一个样本,要用大量的盐摄取,因为我还在弄清楚这个:

class mayaClient(asynchat.async_chat) :


... 

def __init__(self, sock, clientType):

    asynchat.async_chat.__init__(self, sock=sock)

    self.clientType = clientType
    self.ibuffer = []
    self.obuffer = ""
    self.set_terminator("\r\n")
    self.cumulativeResponse = ""


@classmethod
def withSocket(cls, host, clientType, log) :

    melSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    portNumber = cls.MEL_PORT_NUMBER if clientType == cls.MEL else cls.PYTHON_PORT_NUMBER
    melSocket.connect((host, portNumber))   
    return cls(melSocket, clientType, log)


#############################################################
# pushAndWait
#############################################################
def pushAndWait(self, command, timeout=60) :
    """
    ACTION:     Push a command and a "command complete" indicator
                If command completed, return number of milliseconds it took
                If command timed out without completing, return -1

    INPUT:      command as string
                description (optional) as string for more informative logging
                timeout in seconds as int after which to give up

    OUTPUT:     X milliseconds if command completed
                -1 if not

    """

    self.found_terminator()

    incrementToSleep = .001

    self.push("%s\r\n"%command)

    responseToSeek = "Command Complete"
    self.push('Whatever command is going to create readable output for %s`); \r\n'%responseToSeek)

    timeSlept = 0
    while responseToSeek not in self.currentBufferString() and timeSlept < timeout :
        self.read()
        timeSlept += incrementToSleep
        time.sleep(incrementToSleep)

    if responseToSeek in self.currentBufferString() :
        return timeSlept

    return -1


#############################################################
# read
#############################################################
def read(self) :
    """
    ACTION:     Reads the current available output
                and stores it in buffer

    """

    try :

        self.collect_incoming_data(self.recv(1024))

    except Exception, e :

        # Don't worry about it -- just means there's nothing to read
        #
        pass


#############################################################
# currentBuffer
#############################################################
def currentBuffer(self) :

    return self.ibuffer


#############################################################
# currentBufferString
#############################################################
def currentBufferString(self) :

    return "".join(self.ibuffer)


#############################################################
# collect_incoming_data
#############################################################
def collect_incoming_data(self, data):
    """Buffer the data"""

    self.ibuffer.append(data)   


#############################################################
# found_terminator
#############################################################
def found_terminator(self):

    print "Clearing --%s...-- from buffer"%self.currentBufferString()[0:20]
    self.ibuffer = []

答案 1 :(得分:0)

可以参加聚会,但这可以通过telnetlib来完成。下面将读取所有行,直到没有剩余。 timeout=0.1会花一些时间使响应到达。

try:
    while True:             # read until we stop
        message = session.read_until(b'\n', timeout=0.1)
        if message == b'':  # check if there was no data to read
            break           # now we stop
        print(message)      # print message if not stopped
except EOFError:            # If connection was closed
    print('connection closed')

或者如果您始终想等待响应:

try:
    message = session.read_until(b'\n') # Will not timeout until you have response
    print(message)
    while True:             # read until we stop
        message = session.read_until(b'\n', timeout=0.1)
        if message == b'':  # check if there was no data to read
            break           # now we stop
        print(message)      # print message if not stopped
except EOFError:            # If connection was closed
    print('connection closed')