Question

我正在Sanic应用程序中使用asyncssh库（运行Asyncio事件循环）来创建SFTP客户端连接。在我的代码中，我正在这样做：

class MyClass:
    async def connect(self, host, username, password, port):
        return await asyncssh.connect(host=host, port=port, username=username, password=password, known_hosts=None)

    async def establish_sftp_client(self, conn):
        return await conn.start_sftp_client()

    # This is my invoker:
    async def create_connection(self, <some args>):
        conn = await self.connect()
        sftp_client = await self.establish_sftp_client(conn)
        ...
        return conn, sftp_client

尝试执行此操作时出现此错误：

Traceback (most recent call last):
File "/tmp/pycharm_projects/<MY SANIC APP>/requests/helpers.py", line 378, in establish_sftp_client
    return await conn.start_sftp_client()
  File "<MY SANIC APP>/venv/lib/python3.6/site-packages/asyncssh/misc.py", line 182, in __await__
    return (yield from self._coro)
  File "<MY SANIC APP>/venv/lib/python3.6/site-packages/asyncssh/connection.py", line 3503, in start_sftp_client
    encoding=None)
ValueError: too many values to unpack (expected 3)

当我调试它并注销start_sftp_client()实际返回的内容时，我得到了：

（位于0x7f51bbb29dd8的asyncssh.stream.SSHWriter对象，位于0x7f51bbb29da0的asyncssh.stream.SSHReader对象，位于0x7f51b99b7978的asyncssh.stream.SSHReader对象，位于0x7f51bbb29f98的asyncssh.stream.SSHClientStreamSession对象）

因此它实际上返回4个值...而当我查看asyncSSH的源代码时，在start_sftp_client（）实际执行的操作中，它仅查找三个值：

writer, reader, _ = yield from self.open_session(subsystem='sftp', encoding=None)

所以抛出此错误是有道理的...但是为什么？

当我从python控制台运行此方法时-它很好用。通过以下脚本正确创建了一个SFTP客户端：

import asyncssh, asyncio

async def x():
    conn = await asyncssh.connect(host='<host'>, username='some name', password='some pass', port=22, known_hosts=None)
    sftp = await conn.start_sftp_client()
    print("sftp {}".format(sftp)) # This works!

asyncio.get_event_loop().run_until_complete(x())

Answer 1

在将日志语句放置在代码库中的所有位置之后，终于找到了此问题的根本原因。这些行被隐藏在一些晦涩的文件中：

@asyncio.coroutine
def open_session(self, *args, **kwargs):            
    chan, session = yield from self.create_session(CoreSSHClientStreamSession,
                                                   *args, **kwargs)

    return (asyncssh.stream.SSHWriter(session, chan), asyncssh.stream.SSHReader(session, chan),
            asyncssh.stream.SSHReader(session, chan, asyncssh.constants.EXTENDED_DATA_STDERR))


asyncssh.SSHClientConnection.open_session = open_session

最后一行覆盖了asyncssh的open_session方法！

AsyncSSH创建SFTP客户端错误-值太多，无法解压缩

1 个答案: