Source code for duplicity.backends.ssh_paramiko_backend

# -*- Mode:Python; indent-tabs-mode:nil; tab-width:4; encoding:utf-8 -*-
# Copyright 2002 Ben Escoto <>
# Copyright 2007 Kenneth Loafman <>
# Copyright 2011 Alexander Zangerl <>
# Copyright 2012 edso (ssh_config added)
# This file is part of duplicity.
# Duplicity is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation; either version 2 of the License, or (at your
# option) any later version.
# Duplicity is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# General Public License for more details.
# You should have received a copy of the GNU General Public License
# along with duplicity; if not, write to the Free Software Foundation,
# Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

from __future__ import division
from builtins import input
from builtins import oct
from builtins import zip

import errno
import getpass
import logging
import os
import re
import sys
import warnings

from binascii import hexlify

import duplicity.backend
from duplicity import progress
from duplicity import config
from duplicity import util
from duplicity.errors import BackendException

global paramiko

read_blocksize = 65635  # for doing scp retrievals, where we need to read ourselves

[docs]class SSHParamikoBackend(duplicity.backend.Backend): u"""This backend accesses files using the sftp or scp protocols. It does not need any local client programs, but an ssh server and the sftp program must be installed on the remote side (or with scp, the programs scp, ls, mkdir, rm and a POSIX-compliant shell). Authentication keys are requested from an ssh agent if present, then ~/.ssh/id_rsa/dsa are tried. If -oIdentityFile=path is present in --ssh-options, then that file is also tried. The passphrase for any of these keys is taken from the URI or FTP_PASSWORD. If none of the above are available, password authentication is attempted (using the URI or FTP_PASSWORD). Missing directories on the remote side will be created. If scp is active then all operations on the remote side require passing arguments through a shell, which introduces unavoidable quoting issues: directory and file names that contain single quotes will not work. This problem does not exist with sftp. """
[docs] def __init__(self, parsed_url): global paramiko duplicity.backend.Backend.__init__(self, parsed_url) self.retry_delay = 10 if parsed_url.path: # remove first leading '/' self.remote_dir = re.sub(r'^/', r'', parsed_url.path, 1) else: self.remote_dir = u'.' # lazily import paramiko when we need it # debian squeeze's paramiko is a bit old, so we silence randompool # depreciation warning note also: passphrased private keys work with # squeeze's paramiko only if done with DES, not AES with warnings.catch_warnings(): warnings.simplefilter(u"ignore") try: import paramiko except ImportError: raise class AgreedAddPolicy (paramiko.AutoAddPolicy): u""" Policy for showing a yes/no prompt and adding the hostname and new host key to the known host file accordingly. This class simply extends the AutoAddPolicy class with a yes/no prompt. """ def missing_host_key(self, client, hostname, key): fp = hexlify(key.get_fingerprint()) fingerprint = u':'.join(str(a + b) for a, b in list(zip(fp[::2], fp[1::2]))) question = u"""The authenticity of host '%s' can't be established. %s key fingerprint is %s. Are you sure you want to continue connecting (yes/no)? """ % (hostname, key.get_name().upper(), fingerprint) while True: sys.stdout.write(question) choice = input().lower() if choice in [u'yes', u'y']: paramiko.AutoAddPolicy.missing_host_key(self, client, hostname, key) return elif choice in [u'no', u'n']: raise AuthenticityException(hostname) else: question = u"Please type 'yes' or 'no': " class AuthenticityException (paramiko.SSHException): def __init__(self, hostname): paramiko.SSHException.__init__(self, u'Host key verification for server %s failed.' % hostname) self.client = paramiko.SSHClient() self.client.set_missing_host_key_policy(AgreedAddPolicy()) # paramiko uses logging with the normal python severity levels, # but duplicity uses both custom levels and inverted logic...*sigh* self.client.set_log_channel(u"sshbackend") ours = paramiko.util.get_logger(u"sshbackend") dest = logging.StreamHandler(sys.stderr) dest.setFormatter(logging.Formatter(u'ssh: %(message)s')) ours.addHandler(dest) # ..and the duplicity levels are neither linear, # nor are the names compatible with python logging, # eg. 'NOTICE'...WAAAAAH! plevel = logging.getLogger(u"duplicity").getEffectiveLevel() if plevel <= 1: wanted = logging.DEBUG elif plevel <= 5: wanted = logging.INFO elif plevel <= 7: wanted = logging.WARNING elif plevel <= 9: wanted = logging.ERROR else: wanted = logging.CRITICAL ours.setLevel(wanted) # load user/local known_hosts files # paramiko is very picky wrt format and bails out on any problem... global_known_hosts = u"/etc/ssh/ssh_known_hosts" m =""" ^(?:.+\s+)? (?:-oGlobalKnownHostsFile=) ( ([\"']) ([^\\2]+) \\2 | [\S]+ ) """, config.ssh_options, re.VERBOSE) if (m is not None): global_known_hosts = if else try: if os.path.isfile(global_known_hosts): self.client.load_system_host_keys(global_known_hosts) except Exception as e: raise BackendException(f"could not load {global_known_hosts}, maybe corrupt?") user_known_hosts = os.path.expanduser(u"~/.ssh/known_hosts") m =""" ^(?:.+\s+)? (?:-oUserKnownHostsFile=) ( ([\"']) ([^\\2]+) \\2 | [\S]+ ) """, config.ssh_options, re.VERBOSE) if (m is not None): user_known_hosts = if else try: # use load_host_keys() to signal it's writable to paramiko # load if file exists or add filename to create it if needed if os.path.isfile(user_known_hosts): self.client.load_host_keys(user_known_hosts) else: self.client._host_keys_filename = user_known_hosts except Exception as e: raise BackendException(f"could not load {user_known_hosts}, maybe corrupt?") u""" the next block reorganizes all host parameters into a dictionary like SSHConfig does. this dictionary 'self.config' becomes the authorative source for these values from here on. rationale is that it is easiest to deal wrt overwriting multiple values from ssh_config file. (ede 03/2012) """ self.config = {u'hostname': parsed_url.hostname} # get system host config entries self.config.update(self.gethostconfig(u'/etc/ssh/ssh_config', parsed_url.hostname)) # update with user's config file self.config.update(self.gethostconfig(u'~/.ssh/config', parsed_url.hostname)) # update with url values # username from url if parsed_url.username: self.config.update({u'user': parsed_url.username}) # username from input if u'user' not in self.config: self.config.update({u'user': getpass.getuser()}) # port from url if parsed_url.port: self.config.update({u'port': parsed_url.port}) # ensure there is deafult 22 or an int value if u'port' in self.config: self.config.update({u'port': int(self.config[u'port'])}) else: self.config.update({u'port': 22}) # parse ssh options for alternative ssh private key, identity file m =""" ^(?:.+\s+)? (?:-oIdentityFile=|-i\s+) (([\"']) ( [^\\2]+)\\2 | [\S]+ ) """, config.ssh_options, re.VERBOSE) if (m is not None): keyfilename = if else self.config[u'identityfile'] = keyfilename.strip(u'\'\"') # ensure ~ is expanded and identity exists in dictionary if u'identityfile' in self.config: if not isinstance(self.config[u'identityfile'], list): # Paramiko 1.9.0 and earlier do not support multiple # identity files when parsing config files and always # return a string; later versions always return a list, # even if there is only one file given. # # All recent versions seem to support *using* multiple # identity files, though, so to make things easier, we # simply always use a list. self.config[u'identityfile'] = [self.config[u'identityfile']] self.config[u'identityfile'] = [ os.path.expanduser(i) for i in self.config[u'identityfile']] else: self.config[u'identityfile'] = None # get password, enable prompt if askpass is set self.use_getpass = config.ssh_askpass # set url values for beautiful login prompt parsed_url.username = self.config[u'user'] parsed_url.hostname = self.config[u'hostname'] password = self.get_password() try: self.client.connect(hostname=self.config[u'hostname'], port=self.config[u'port'], username=self.config[u'user'], password=password, allow_agent=True, look_for_keys=True, key_filename=self.config[u'identityfile']) except Exception as e: raise BackendException(u"ssh connection to %s@%s:%d failed: %s" % ( self.config[u'user'], self.config[u'hostname'], self.config[u'port'], e)) self.client.get_transport().set_keepalive((int)(config.timeout / 2)) self.scheme = duplicity.backend.strip_prefix(parsed_url.scheme, u'paramiko') self.use_scp = (self.scheme == u'scp') # scp or sftp? if (self.use_scp): # sanity-check the directory name if ("'", self.remote_dir)): raise BackendException(u"cannot handle directory names with single quotes with scp") # make directory if needed self.runremote(u"mkdir -p '%s'" % (self.remote_dir,), False, u"scp mkdir ") else: try: self.sftp = self.client.open_sftp() except Exception as e: raise BackendException(u"sftp negotiation failed: %s" % e) # move to the appropriate directory, possibly after creating it and its parents dirs = self.remote_dir.split(os.sep) if len(dirs) > 0: if dirs[0] == u'': dirs[0] = u'/' for d in dirs: if (d == u''): continue try: attrs = self.sftp.stat(d) except IOError as e: if e.errno == errno.ENOENT: try: self.sftp.mkdir(d) except Exception as e: raise BackendException(u"sftp mkdir %s failed: %s" % (self.sftp.normalize(u".") + u"/" + d, e)) else: raise BackendException(u"sftp stat %s failed: %s" % (self.sftp.normalize(u".") + u"/" + d, e)) try: self.sftp.chdir(d) except Exception as e: raise BackendException(u"sftp chdir to %s failed: %s" % (self.sftp.normalize(u".") + u"/" + d, e))
[docs] def _put(self, source_path, remote_filename): # remote_filename is a byte object, not str or unicode remote_filename = util.fsdecode(remote_filename) if self.use_scp: f = open(, u'rb') try: chan = self.client.get_transport().open_session() chan.settimeout(config.timeout) # scp in sink mode uses the arg as base directory chan.exec_command(u"scp -t '%s'" % self.remote_dir) except Exception as e: raise BackendException(u"scp execution failed: %s" % e) # scp protocol: one 0x0 after startup, one after the Create meta, # one after saving if there's a problem: 0x1 or 0x02 and some error # text response = chan.recv(1) if (response != b"\0"): raise BackendException(b"scp remote error: %b" % chan.recv(-1)) fstat = os.stat( chan.send(u'C%s %d %s\n' % (oct(fstat.st_mode)[-4:], fstat.st_size, remote_filename)) response = chan.recv(1) if (response != b"\0"): raise BackendException(b"scp remote error: %b" % chan.recv(-1)) file_pos = 0 file_size = fstat.st_size while file_pos < file_size: chan.sendall( file_pos = f.tell() progress.report_transfer(file_pos, file_size) chan.sendall(b'\0') f.close() response = chan.recv(1) if (response != b"\0"): raise BackendException(u"scp remote error: %s" % chan.recv(-1)) chan.close() else: self.sftp.put(, remote_filename, callback=progress.report_transfer)
[docs] def _get(self, remote_filename, local_path): # remote_filename is a byte object, not str or unicode remote_filename = util.fsdecode(remote_filename) if self.use_scp: try: chan = self.client.get_transport().open_session() chan.settimeout(config.timeout) chan.exec_command(u"scp -f '%s/%s'" % (self.remote_dir, remote_filename)) except Exception as e: raise BackendException(u"scp execution failed: %s" % e) chan.send(u'\0') # overall ready indicator msg = chan.recv(-1) if isinstance(msg, bytes): # make msg into str msg = msg.decode() m = re.match(r"C([0-7]{4})\s+(\d+)\s+(\S.*)$", msg) if (m is None or != remote_filename): raise BackendException(u"scp get %s failed: incorrect response '%s'" % (remote_filename, msg)) chan.recv(1) # dispose of the newline trailing the C message size = int( togo = size f = open(, u'wb') chan.send(u'\0') # ready for data try: while togo > 0: if togo > read_blocksize: blocksize = read_blocksize else: blocksize = togo buff = chan.recv(blocksize) f.write(buff) togo -= len(buff) except Exception as e: raise BackendException(u"scp get %s failed: %s" % (remote_filename, e)) msg = chan.recv(1) # check the final status if msg != b'\0': raise BackendException(u"scp get %s failed: %s" % (remote_filename, chan.recv(-1))) f.close() chan.send(u'\0') # send final done indicator chan.close() else: self.sftp.get(remote_filename,
[docs] def _list(self): # In scp mode unavoidable quoting issues will make this fail if the # directory name contains single quotes. if self.use_scp: output = self.runremote(u"ls -1 '%s'" % self.remote_dir, False, u"scp dir listing ") return output.splitlines() else: return self.sftp.listdir()
[docs] def _delete(self, filename): # filename is a byte object, not str or unicode filename = util.fsdecode(filename) # In scp mode unavoidable quoting issues will cause failures if # filenames containing single quotes are encountered. if self.use_scp: self.runremote(u"rm '%s/%s'" % (self.remote_dir, filename), False, u"scp rm ") else: self.sftp.remove(filename)
[docs] def runremote(self, cmd, ignoreexitcode=False, errorprefix=u""): u"""small convenience function that opens a shell channel, runs remote command and returns stdout of command. throws an exception if exit code!=0 and not ignored""" try: ch_in, ch_out, ch_err = self.client.exec_command(cmd, -1, config.timeout) output = return output except Exception as e: if not ignoreexitcode: raise BackendException(u"%sfailed: %s \n %s" % ( errorprefix, cmd, util.uexc(e)))
[docs] def gethostconfig(self, file, host): file = os.path.expanduser(file) if not os.path.isfile(file): return {} sshconfig = paramiko.SSHConfig() try: sshconfig.parse(open(file)) except Exception as e: raise BackendException(u"could not load '%s', maybe corrupt?" % (file)) return sshconfig.lookup(host)
duplicity.backend.register_backend(u"sftp", SSHParamikoBackend) duplicity.backend.register_backend(u"scp", SSHParamikoBackend) duplicity.backend.register_backend(u"paramiko+sftp", SSHParamikoBackend) duplicity.backend.register_backend(u"paramiko+scp", SSHParamikoBackend) duplicity.backend.uses_netloc.extend([u'sftp', u'scp', u'paramiko+sftp', u'paramiko+scp'])