Python telnetlib read_until返回截断字符串 [英] Python telnetlib read_until returns cut off string

问题描述

"read_until"；函数使用长命令返回截断的字符串.
这些命令可以完美运行，但不会显示全文.
我怎样才能解决这个问题?请帮忙.

"read_until" function returns cut off string with long commands.
The commands ran perfectly, but it does not show full texts.
How can I fix this? Please help.

#我的代码

tn = telnetlib.Telnet(ip, 23, 5)
prompt = ']# '
tn.write('echo "this is a long command for the test purpose... > test.txt"\n')
print tn.read_until(prompt, 1)

#调试输出

Telnet(192.168.220.4,23):发送"echo"，这是用于测试目的的长命令...> test.txt""\ n'
Telnet(192.168.220.4,23):recv'echo'this is l'
Telnet(192.168.220.4,23):recv'ong命令用于测试目的...> te \ r \ x00<他是'
Telnet(192.168.220.4,23):recv'用于测试目的的长命令...> tes'
Telnet(192.168.220.4,23):接收'\ x08 \ x08 \ x08 \ x08 \ x08 \ x08 \ x08 \ x08 \ x08 \ x08 \ x08 \ x08 \ x08 \ x08 \ x08 \ x08 \ x08 \ x08 \ x08 \ x08 \ x08 \ x08 \ x08 \ x08 \ x08 \ x0 8t.txt"'
Telnet(192.168.220.4,23):recv'\ r \ n这是用于测试目的的长命令...>'
Telnet(192.168.220.4,23):recv'test.txt \ r \ n [root @ RHEL6-5 tmp]#'

Telnet(192.168.220.4,23): send 'echo "this is a long command for the test purpose... > test.txt"\n'
Telnet(192.168.220.4,23): recv 'echo "this is a l'
Telnet(192.168.220.4,23): recv 'ong command for the test purpose... > te\r\x00<his is '
Telnet(192.168.220.4,23): recv 'a long command for the test purpose... > tes '
Telnet(192.168.220.4,23): recv ' \x08\x08\x08\x08\x08\x08\x08\x08\x08\x08\x08\x08\x08\x08\x08\x08\x08\x08\x08\x08\x08\x08\x08\x08\x0 8t.txt"'
Telnet(192.168.220.4,23): recv '\r\nthis is a long command for the test purpose... >'
Telnet(192.168.220.4,23): recv ' test.txt\r\n[root@RHEL6-5 tmp]# '

#个实际输出

<出于测试目的，他是一个很长的命令...> test.txt"
对于测试目的，这是一个很长的命令...> test.txt
[root @ RHEL6-5 tmp]#

<his is a long command for the test purpose... > test.txt"
this is a long command for the test purpose... > test.txt
[root@RHEL6-5 tmp]#

推荐答案

该问题似乎是由于换行引起的. 我找到了一种解决方案，将窗口大小的宽度设置为接近最大值，可以接收长行而无需telnet服务器应用换行.

The issue appears to be occurring due to line-wrapping. I found a solution where setting the window size width to near the max value allows long lines to be received without line-wrapping applied by the telnet server.

(有关设置选项的详细信息，请参见窗口大小选项 RFC. https://www.ietf.org/rfc/rfc1073.txt )

(See the Window Size Option RFC for details on setting the option https://www.ietf.org/rfc/rfc1073.txt )

import telnetlib
import struct
from telnetlib import DO, DONT, IAC, WILL, WONT, NAWS, SB, SE

MAX_WINDOW_WIDTH = 65000  # Max Value: 65535
MAX_WINDOW_HEIGHT = 5000


def set_max_window_size(tsocket, command, option):
    """
    Set Window size to resolve line width issue
    Set Windows size command: IAC SB NAWS <16-bit value> <16-bit value> IAC SE
    --> inform the Telnet server of the window width and height.
    Refer to https://www.ietf.org/rfc/rfc1073.txt
    :param tsocket: telnet socket object
    :param command: telnet Command
    :param option: telnet option
    :return: None
    """
    if option == NAWS:
        width = struct.pack('H', MAX_WINDOW_WIDTH)
        height = struct.pack('H', MAX_WINDOW_HEIGHT)
        tsocket.send(IAC + WILL + NAWS)
        tsocket.send(IAC + SB + NAWS + width + height + IAC + SE)
    # -- below code taken from telnetlib source
    elif command in (DO, DONT):
        tsocket.send(IAC + WONT + option)
    elif command in (WILL, WONT):
        tsocket.send(IAC + DONT + option)

ip = 'x.x.x.x'
tn = telnetlib.Telnet(ip, 23, timeout=5)
tn.set_option_negotiation_callback(set_max_window_size)

tn.write('echo "this is a long command for the test purpose... > test.txt"\n')

prompt = ']# '
print tn.read_until(prompt, timeout=1)

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