ssh_exception.py

# Copyright (C) 2003-2007  Robey Pointer <robeypointer@gmail.com>
#
# This file is part of paramiko.
#
# Paramiko is free software; you can redistribute it and/or modify it under the
# terms of the GNU Lesser General Public License as published by the Free
# Software Foundation; either version 2.1 of the License, or (at your option)
# any later version.
#
# Paramiko is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
# A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more
# details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with Paramiko; if not, write to the Free Software Foundation, Inc.,
# 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.

import socket


class SSHException (Exception):
    """
    Exception raised by failures in SSH2 protocol negotiation or logic errors.
    """
    pass


class AuthenticationException (SSHException):
    """
    Exception raised when authentication failed for some reason.  It may be
    possible to retry with different credentials.  (Other classes specify more
    specific reasons.)
    
    .. versionadded:: 1.6
    """
    pass
    

class PasswordRequiredException (AuthenticationException):
    """
    Exception raised when a password is needed to unlock a private key file.
    """
    pass


class BadAuthenticationType (AuthenticationException):
    """
    Exception raised when an authentication type (like password) is used, but
    the server isn't allowing that type.  (It may only allow public-key, for
    example.)
    
    :ivar list allowed_types:
        list of allowed authentication types provided by the server (possible
        values are: ``"none"``, ``"password"``, and ``"publickey"``).
    
    .. versionadded:: 1.1
    """
    allowed_types = []
    
    def __init__(self, explanation, types):
        AuthenticationException.__init__(self, explanation)
        self.allowed_types = types
        # for unpickling
        self.args = (explanation, types, )

    def __str__(self):
        return SSHException.__str__(self) + ' (allowed_types=%r)' % self.allowed_types


class PartialAuthentication (AuthenticationException):
    """
    An internal exception thrown in the case of partial authentication.
    """
    allowed_types = []
    
    def __init__(self, types):
        AuthenticationException.__init__(self, 'partial authentication')
        self.allowed_types = types
        # for unpickling
        self.args = (types, )


class ChannelException (SSHException):
    """
    Exception raised when an attempt to open a new `.Channel` fails.
    
    :ivar int code: the error code returned by the server
    
    .. versionadded:: 1.6
    """
    def __init__(self, code, text):
        SSHException.__init__(self, text)
        self.code = code
        # for unpickling
        self.args = (code, text, )


class BadHostKeyException (SSHException):
    """
    The host key given by the SSH server did not match what we were expecting.
    
    :ivar str hostname: the hostname of the SSH server
    :ivar PKey got_key: the host key presented by the server
    :ivar PKey expected_key: the host key expected
    
    .. versionadded:: 1.6
    """
    def __init__(self, hostname, got_key, expected_key):
        SSHException.__init__(self,
                              'Host key for server %s does not match : got %s expected %s' % (
                                  hostname,
                                  got_key.get_base64(),
                                  expected_key.get_base64()))
        self.hostname = hostname
        self.key = got_key
        self.expected_key = expected_key
        # for unpickling
        self.args = (hostname, got_key, expected_key, )


class ProxyCommandFailure (SSHException):
    """
    The "ProxyCommand" found in the .ssh/config file returned an error.

    :ivar str command: The command line that is generating this exception.
    :ivar str error: The error captured from the proxy command output.
    """
    def __init__(self, command, error):
        SSHException.__init__(self,
            '"ProxyCommand (%s)" returned non-zero exit status: %s' % (
                command, error
            )
        )
        self.error = error
        # for unpickling
        self.args = (command, error, )


class NoValidConnectionsError(socket.error):
    """
    Multiple connection attempts were made and no families succeeded.

    This exception class wraps multiple "real" underlying connection errors,
    all of which represent failed connection attempts. Because these errors are
    not guaranteed to all be of the same error type (i.e. different errno,
    `socket.error` subclass, message, etc) we expose a single unified error
    message and a ``None`` errno so that instances of this class match most
    normal handling of `socket.error` objects.
    
    To see the wrapped exception objects, access the ``errors`` attribute.
    ``errors`` is a dict whose keys are address tuples (e.g. ``('127.0.0.1',
    22)``) and whose values are the exception encountered trying to connect to
    that address.

    It is implied/assumed that all the errors given to a single instance of
    this class are from connecting to the same hostname + port (and thus that
    the differences are in the resolution of the hostname - e.g. IPv4 vs v6).
    """
    def __init__(self, errors):
        """
        :param dict errors:
            The errors dict to store, as described by class docstring.
        """
        addrs = list(errors.keys())
        body = ', '.join([x[0] for x in addrs[:-1]])
        tail = addrs[-1][0]
        msg = "Unable to connect to port {0} on {1} or {2}"
        super(NoValidConnectionsError, self).__init__(
            None, # stand-in for errno
            msg.format(addrs[0][1], body, tail)
        )
        self.errors = errors