为什么在字典中存储SFTP对象时Paramiko会引发EOFError()?

Question

我在写一个应用程序时遇到了一些麻烦，这个程序是用来通过SSH下载和上传文件的。现在的问题是，我可以顺利下载文件，但当我尝试把文件上传到另一个服务器时，就会出现EOFError()的错误。我查看了paramiko\sftp.py中的_write_all()函数，发现这个错误似乎是因为它无法将数据写入流中？我对网络编程没有经验，所以如果有人能告诉我它到底在做什么，我会非常感激。

我写了一个简化版的函数来处理我的连接，ssh().runCommand()展示了我的应用程序中上传失败的情况，而simpleTest()则展示了sftp put是如何成功的，但我看不出runCommand()和simpleTest()之间有什么不同，除了我的SFTP对象存储方式不同。一个是存储在字典里，另一个是单独存储。如果字典是问题所在，那下载文件应该也会失败，但事实并非如此。

有没有人知道可能导致这种情况的原因，或者能推荐另一种管理连接的方式，如果现在的方式有问题的话？

我使用的是Python 2.7和Paramiko 1.7.6。我在Linux和Windows上测试了这段代码，结果都是一样的。

编辑：现在包含了代码。

import os
import paramiko

class ManageSSH:
     """Manages ssh connections."""
    def __init__(self):
        self.hosts = {"testbox": ['testbox', 'test', 'test']}
        self.sshConnections = {}
        self.sftpConnections = {}
        self.localfile = "C:\\testfile"
        self.remotefile = "/tmp/tempfile"
        self.fetchedfile = "C:\\tempdl"

    def ssh(self):
        """Manages ssh connections."""
        for host in self.hosts.keys():
            try:
                self.sshConnections[host]
                print "ssh connection is already open for %s" % host
            except KeyError, e:         # if no ssh connection for the host exists then open one
                # open ssh connection
                ssh = paramiko.SSHClient()
                ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
                ssh.connect(self.hosts[host][0], 22, self.hosts[host][1], self.hosts[host][2])
                self.sshConnections[host] = ssh
                print "ssh connection to %s opened" % host
            try:
                self.sftpConnections[host]
                print "sftp connection is already open for %s" % host
            except KeyError, e:
                # open sftp connection
                ssh = paramiko.SSHClient()
                ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
                ssh.connect(self.hosts[host][0], 22, self.hosts[host][1], self.hosts[host][2])
                self.sftpConnections[host] = ssh.open_sftp()
                print "sftp connection to %s opened" % host

    def runCommand(self):
        """run commands and return output"""
        for host in self.hosts:
            command = "if [ -d /tmp ]; then echo -n 1; else echo -n 0; fi"
            stdin, stdout, stderr = self.sshConnections[host].exec_command(command)
            print "%s executed on %s" % (command, host)
            print "returned %s" % stdout.read()
            self.sftpConnections.get(self.remotefile, self.fetchedfile)
            print "downloaded %s from %s" % (self.remotefile, host)
            self.sftpConnections[host].put(self.localfile, self.remotefile)
            print "uploaded %s to %s" % (self.localfile, host)
            self.sftpConnections[host].close()
            self.sshConnections[host].close()

    def simpleTest(self):
        host = "testbox"
        ssh = paramiko.SSHClient()
        ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
        ssh.connect(host, 22, 'test', 'test')
        sftp = ssh.open_sftp()
        print "sftp connection to %s opened" % host
        sftp.get(self.remotefile, self.fetchedfile)
        print "downloaded %s from %s" % (self.localfile, host)
        sftp.put(self.localfile, self.remotefile)
        print "uploaded %s to %s" % (self.localfile, host)
        sftp.close()

if __name__ == "__main__":
    test = ManageSSH()
    print "running test that works"
    test.simpleTest()
    print "running test that fails"
    test.ssh()
    test.runCommand()

输出：

running test that works
sftp connection to testbox opened
downloaded C:\testfile from testbox
uploaded C:\testfile to testbox
running test that fails
ssh connection to testbox opened
sftp connection to testbox opened
if [ -d /tmp ]; then echo -n 1; else echo -n 0; fi executed on testbox
returned 1
downloaded /tmp/tempfile from testbox
Traceback (most recent call last):
  File "paramikotest.py", line 71, in <module>
    test.runCommand()
  File "paramikotest.py", line 47, in runCommand
    self.sftpConnections[host].put(self.localfile, self.remotefile)
  File "C:\Python27\lib\site-packages\paramiko\sftp_client.py", line 561, in put

    fr = self.file(remotepath, 'wb')
  File "C:\Python27\lib\site-packages\paramiko\sftp_client.py", line 245, in open
    t, msg = self._request(CMD_OPEN, filename, imode, attrblock)
  File "C:\Python27\lib\site-packages\paramiko\sftp_client.py", line 627, in _request
    num = self._async_request(type(None), t, *arg)
  File "C:\Python27\lib\site-packages\paramiko\sftp_client.py", line 649, in _async_request
    self._send_packet(t, str(msg))
  File "C:\Python27\lib\site-packages\paramiko\sftp.py", line 172, in _send_packet
    self._write_all(out)
  File "C:\Python27\lib\site-packages\paramiko\sftp.py", line 138, in _write_all

    raise EOFError()
EOFError

错误处理 ssh 文件传输网络编程连接管理 paramiko sftp EOFError

为什么在字典中存储SFTP对象时Paramiko会引发EOFError()?

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