~bzr-pqm/bzr/bzr.dev

# Copyright (C) 2005 Robey Pointer <robey@lag.net>

# Copyright (C) 2005, 2006 Canonical Ltd

# This program 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.

# This program 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 General Public License for more details.

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

"""Implementation of Transport over SFTP, using paramiko."""

import errno

import getpass

import os

import random

import re

import stat

import subprocess

import sys

import time

import urllib

import urlparse

import weakref

from bzrlib.config import config_dir, ensure_config_dir_exists

from bzrlib.errors import (ConnectionError,

                           FileExists, 

                           TransportNotPossible, NoSuchFile, PathNotChild,

                           TransportError,

                           LockError, 

                           PathError,

                           ParamikoNotPresent,

                           )

from bzrlib.osutils import pathjoin, fancy_rename

from bzrlib.trace import mutter, warning, error

from bzrlib.transport import (

    register_urlparse_netloc_protocol,

    Server,

    split_url,

    Transport,

    )

import bzrlib.ui

import bzrlib.urlutils as urlutils

try:

    import paramiko

except ImportError, e:

    raise ParamikoNotPresent(e)

else:

    from paramiko.sftp import (SFTP_FLAG_WRITE, SFTP_FLAG_CREATE,

                               SFTP_FLAG_EXCL, SFTP_FLAG_TRUNC,

                               CMD_HANDLE, CMD_OPEN)

    from paramiko.sftp_attr import SFTPAttributes

    from paramiko.sftp_file import SFTPFile

    from paramiko.sftp_client import SFTPClient

register_urlparse_netloc_protocol('sftp')

def _ignore_sigint():

    # TODO: This should possibly ignore SIGHUP as well, but bzr currently

    # doesn't handle it itself.

    # <https://launchpad.net/products/bzr/+bug/41433/+index>

    import signal

    signal.signal(signal.SIGINT, signal.SIG_IGN)

def os_specific_subprocess_params():

    """Get O/S specific subprocess parameters."""

    if sys.platform == 'win32':

        # setting the process group and closing fds is not supported on 

        # win32

        return {}

    else:

        # We close fds other than the pipes as the child process does not need 

        # them to be open.

        #

        # We also set the child process to ignore SIGINT.  Normally the signal

        # would be sent to every process in the foreground process group, but

        # this causes it to be seen only by bzr and not by ssh.  Python will

        # generate a KeyboardInterrupt in bzr, and we will then have a chance

        # to release locks or do other cleanup over ssh before the connection

        # goes away.  

        # <https://launchpad.net/products/bzr/+bug/5987>

        #

        # Running it in a separate process group is not good because then it

        # can't get non-echoed input of a password or passphrase.

        # <https://launchpad.net/products/bzr/+bug/40508>

        return {'preexec_fn': _ignore_sigint,

                'close_fds': True,

                }

# don't use prefetch unless paramiko version >= 1.5.2 (there were bugs earlier)

_default_do_prefetch = False

if getattr(paramiko, '__version_info__', (0, 0, 0)) >= (1, 5, 5):

    _default_do_prefetch = True

_ssh_vendor = None

def _get_ssh_vendor():

    """Find out what version of SSH is on the system."""

    global _ssh_vendor

    if _ssh_vendor is not None:

        return _ssh_vendor

    _ssh_vendor = 'none'

    if 'BZR_SSH' in os.environ:

        _ssh_vendor = os.environ['BZR_SSH']

        if _ssh_vendor == 'paramiko':

            _ssh_vendor = 'none'

        return _ssh_vendor

    try:

        p = subprocess.Popen(['ssh', '-V'],

                             stdin=subprocess.PIPE,

                             stdout=subprocess.PIPE,

                             stderr=subprocess.PIPE,

                             **os_specific_subprocess_params())

        returncode = p.returncode

        stdout, stderr = p.communicate()

    except OSError:

        returncode = -1

        stdout = stderr = ''

    if 'OpenSSH' in stderr:

        mutter('ssh implementation is OpenSSH')

        _ssh_vendor = 'openssh'

    elif 'SSH Secure Shell' in stderr:

        mutter('ssh implementation is SSH Corp.')

        _ssh_vendor = 'ssh'

    if _ssh_vendor != 'none':

        return _ssh_vendor

    # XXX: 20051123 jamesh

    # A check for putty's plink or lsh would go here.

    mutter('falling back to paramiko implementation')

    return _ssh_vendor

class SFTPSubprocess:

    """A socket-like object that talks to an ssh subprocess via pipes."""

    def __init__(self, hostname, vendor, port=None, user=None):

        assert vendor in ['openssh', 'ssh']

        if vendor == 'openssh':

            args = ['ssh',

                    '-oForwardX11=no', '-oForwardAgent=no',

                    '-oClearAllForwardings=yes', '-oProtocol=2',

                    '-oNoHostAuthenticationForLocalhost=yes']

            if port is not None:

                args.extend(['-p', str(port)])

            if user is not None:

                args.extend(['-l', user])

            args.extend(['-s', hostname, 'sftp'])

        elif vendor == 'ssh':

            args = ['ssh', '-x']

            if port is not None:

                args.extend(['-p', str(port)])

            if user is not None:

                args.extend(['-l', user])

            args.extend(['-s', 'sftp', hostname])

        self.proc = subprocess.Popen(args,

                                     stdin=subprocess.PIPE,

                                     stdout=subprocess.PIPE,

                                     **os_specific_subprocess_params())

    def send(self, data):

        return os.write(self.proc.stdin.fileno(), data)

    def recv_ready(self):

        # TODO: jam 20051215 this function is necessary to support the

        # pipelined() function. In reality, it probably should use

        # poll() or select() to actually return if there is data

        # available, otherwise we probably don't get any benefit

        return True

    def recv(self, count):

        return os.read(self.proc.stdout.fileno(), count)

    def close(self):

        self.proc.stdin.close()

        self.proc.stdout.close()

        self.proc.wait()

class LoopbackSFTP(object):

    """Simple wrapper for a socket that pretends to be a paramiko Channel."""

    def __init__(self, sock):

        self.__socket = sock

    def send(self, data):

        return self.__socket.send(data)

    def recv(self, n):

        return self.__socket.recv(n)

    def recv_ready(self):

        return True

    def close(self):

        self.__socket.close()

SYSTEM_HOSTKEYS = {}

BZR_HOSTKEYS = {}

# This is a weakref dictionary, so that we can reuse connections

# that are still active. Long term, it might be nice to have some

# sort of expiration policy, such as disconnect if inactive for

# X seconds. But that requires a lot more fanciness.

_connected_hosts = weakref.WeakValueDictionary()

def clear_connection_cache():

    """Remove all hosts from the SFTP connection cache.

    Primarily useful for test cases wanting to force garbage collection.

    """

    _connected_hosts.clear()

def load_host_keys():

    """

    Load system host keys (probably doesn't work on windows) and any

    "discovered" keys from previous sessions.

    """

    global SYSTEM_HOSTKEYS, BZR_HOSTKEYS

    try:

        SYSTEM_HOSTKEYS = paramiko.util.load_host_keys(os.path.expanduser('~/.ssh/known_hosts'))

    except Exception, e:

        mutter('failed to load system host keys: ' + str(e))

    bzr_hostkey_path = pathjoin(config_dir(), 'ssh_host_keys')

    try:

        BZR_HOSTKEYS = paramiko.util.load_host_keys(bzr_hostkey_path)

    except Exception, e:

        mutter('failed to load bzr host keys: ' + str(e))

        save_host_keys()

def save_host_keys():

    """

    Save "discovered" host keys in $(config)/ssh_host_keys/.

    """

    global SYSTEM_HOSTKEYS, BZR_HOSTKEYS

    bzr_hostkey_path = pathjoin(config_dir(), 'ssh_host_keys')

    ensure_config_dir_exists()

    try:

        f = open(bzr_hostkey_path, 'w')

        f.write('# SSH host keys collected by bzr\n')

        for hostname, keys in BZR_HOSTKEYS.iteritems():

            for keytype, key in keys.iteritems():

                f.write('%s %s %s\n' % (hostname, keytype, key.get_base64()))

        f.close()

    except IOError, e:

        mutter('failed to save bzr host keys: ' + str(e))

class SFTPLock(object):

    """This fakes a lock in a remote location."""

    __slots__ = ['path', 'lock_path', 'lock_file', 'transport']

    def __init__(self, path, transport):

        assert isinstance(transport, SFTPTransport)

        self.lock_file = None

        self.path = path

        self.lock_path = path + '.write-lock'

        self.transport = transport

        try:

            # RBC 20060103 FIXME should we be using private methods here ?

            abspath = transport._remote_path(self.lock_path)

            self.lock_file = transport._sftp_open_exclusive(abspath)

        except FileExists:

            raise LockError('File %r already locked' % (self.path,))

    def __del__(self):

        """Should this warn, or actually try to cleanup?"""

        if self.lock_file:

            warning("SFTPLock %r not explicitly unlocked" % (self.path,))

            self.unlock()

    def unlock(self):

        if not self.lock_file:

            return

        self.lock_file.close()

        self.lock_file = None

        try:

            self.transport.delete(self.lock_path)

        except (NoSuchFile,):

            # What specific errors should we catch here?

            pass

class SFTPTransport (Transport):

    """

    Transport implementation for SFTP access.

    """

    _do_prefetch = _default_do_prefetch

    def __init__(self, base, clone_from=None):

        assert base.startswith('sftp://')

        self._parse_url(base)

        base = self._unparse_url()

        if base[-1] != '/':

            base += '/'

        super(SFTPTransport, self).__init__(base)

        if clone_from is None:

            self._sftp_connect()

        else:

            # use the same ssh connection, etc

            self._sftp = clone_from._sftp

        # super saves 'self.base'

    def should_cache(self):

        """

        Return True if the data pulled across should be cached locally.

        """

        return True

    def clone(self, offset=None):

        """

        Return a new SFTPTransport with root at self.base + offset.

        We share the same SFTP session between such transports, because it's

        fairly expensive to set them up.

        """

        if offset is None:

            return SFTPTransport(self.base, self)

        else:

            return SFTPTransport(self.abspath(offset), self)

    def abspath(self, relpath):

        """

        Return the full url to the given relative path.

        @param relpath: the relative path or path components

        @type relpath: str or list

        """

        return self._unparse_url(self._remote_path(relpath))

    def _remote_path(self, relpath):

        """Return the path to be passed along the sftp protocol for relpath.

        relpath is a urlencoded string.

        """

        # FIXME: share the common code across transports

        assert isinstance(relpath, basestring)

        relpath = urlutils.unescape(relpath).split('/')

        basepath = self._path.split('/')

        if len(basepath) > 0 and basepath[-1] == '':

            basepath = basepath[:-1]

        for p in relpath:

            if p == '..':

                if len(basepath) == 0:

                    # In most filesystems, a request for the parent

                    # of root, just returns root.

                    continue

                basepath.pop()

            elif p == '.':

                continue # No-op

            else:

                basepath.append(p)

        path = '/'.join(basepath)

        return path

    def relpath(self, abspath):

        username, password, host, port, path = self._split_url(abspath)

        error = []

        if (username != self._username):

            error.append('username mismatch')

        if (host != self._host):

            error.append('host mismatch')

        if (port != self._port):

            error.append('port mismatch')

        if (not path.startswith(self._path)):

            error.append('path mismatch')

        if error:

            extra = ': ' + ', '.join(error)

            raise PathNotChild(abspath, self.base, extra=extra)

        pl = len(self._path)

        return path[pl:].strip('/')

    def has(self, relpath):

        """

        Does the target location exist?

        """

        try:

            self._sftp.stat(self._remote_path(relpath))

            return True

        except IOError:

            return False

    def get(self, relpath):

        """

        Get the file at the given relative path.

        :param relpath: The relative path to the file

        """

        try:

            path = self._remote_path(relpath)

            f = self._sftp.file(path, mode='rb')

            if self._do_prefetch and (getattr(f, 'prefetch', None) is not None):

                f.prefetch()

            return f

        except (IOError, paramiko.SSHException), e:

            self._translate_io_exception(e, path, ': error retrieving')

    def get_partial(self, relpath, start, length=None):

        """

        Get just part of a file.

        :param relpath: Path to the file, relative to base

        :param start: The starting position to read from

        :param length: The length to read. A length of None indicates

                       read to the end of the file.

        :return: A file-like object containing at least the specified bytes.

                 Some implementations may return objects which can be read

                 past this length, but this is not guaranteed.

        """

        # TODO: implement get_partial_multi to help with knit support

        f = self.get(relpath)

        f.seek(start)

        if self._do_prefetch and hasattr(f, 'prefetch'):

            f.prefetch()

        return f

    def put(self, relpath, f, mode=None):

        """

        Copy the file-like or string object into the location.

        :param relpath: Location to put the contents, relative to base.

        :param f:       File-like or string object.

        :param mode: The final mode for the file

        """

        final_path = self._remote_path(relpath)

        self._put(final_path, f, mode=mode)

    def _put(self, abspath, f, mode=None):

        """Helper function so both put() and copy_abspaths can reuse the code"""

        tmp_abspath = '%s.tmp.%.9f.%d.%d' % (abspath, time.time(),

                        os.getpid(), random.randint(0,0x7FFFFFFF))

        fout = self._sftp_open_exclusive(tmp_abspath, mode=mode)

        closed = False

        try:

            try:

                fout.set_pipelined(True)

                self._pump(f, fout)

            except (IOError, paramiko.SSHException), e:

                self._translate_io_exception(e, tmp_abspath)

            if mode is not None:

                self._sftp.chmod(tmp_abspath, mode)

            fout.close()

            closed = True

            self._rename_and_overwrite(tmp_abspath, abspath)

        except Exception, e:

            # If we fail, try to clean up the temporary file

            # before we throw the exception

            # but don't let another exception mess things up

            # Write out the traceback, because otherwise

            # the catch and throw destroys it

            import traceback

            mutter(traceback.format_exc())

            try:

                if not closed:

                    fout.close()

                self._sftp.remove(tmp_abspath)

            except:

                # raise the saved except

                raise e

            # raise the original with its traceback if we can.

            raise

    def iter_files_recursive(self):

        """Walk the relative paths of all files in this transport."""

        queue = list(self.list_dir('.'))

        while queue:

            relpath = urllib.quote(queue.pop(0))

            st = self.stat(relpath)

            if stat.S_ISDIR(st.st_mode):

                for i, basename in enumerate(self.list_dir(relpath)):

                    queue.insert(i, relpath+'/'+basename)

            else:

                yield relpath

    def mkdir(self, relpath, mode=None):

        """Create a directory at the given path."""

        try:

            path = self._remote_path(relpath)

            # In the paramiko documentation, it says that passing a mode flag 

            # will filtered against the server umask.

            # StubSFTPServer does not do this, which would be nice, because it is

            # what we really want :)

            # However, real servers do use umask, so we really should do it that way

            self._sftp.mkdir(path)

            if mode is not None:

                self._sftp.chmod(path, mode=mode)

        except (paramiko.SSHException, IOError), e:

            self._translate_io_exception(e, path, ': unable to mkdir',

                failure_exc=FileExists)

    def _translate_io_exception(self, e, path, more_info='', 

                                failure_exc=PathError):

        """Translate a paramiko or IOError into a friendlier exception.

        :param e: The original exception

        :param path: The path in question when the error is raised

        :param more_info: Extra information that can be included,

                          such as what was going on

        :param failure_exc: Paramiko has the super fun ability to raise completely

                           opaque errors that just set "e.args = ('Failure',)" with

                           no more information.

                           If this parameter is set, it defines the exception 

                           to raise in these cases.

        """

        # paramiko seems to generate detailless errors.

        self._translate_error(e, path, raise_generic=False)

        if hasattr(e, 'args'):

            if (e.args == ('No such file or directory',) or

                e.args == ('No such file',)):

                raise NoSuchFile(path, str(e) + more_info)

            if (e.args == ('mkdir failed',)):

                raise FileExists(path, str(e) + more_info)

            # strange but true, for the paramiko server.

            if (e.args == ('Failure',)):

                raise failure_exc(path, str(e) + more_info)

            mutter('Raising exception with args %s', e.args)

        if hasattr(e, 'errno'):

            mutter('Raising exception with errno %s', e.errno)

        raise e

    def append(self, relpath, f, mode=None):

        """

        Append the text in the file-like object into the final

        location.

        """

        try:

            path = self._remote_path(relpath)

            fout = self._sftp.file(path, 'ab')

            if mode is not None:

                self._sftp.chmod(path, mode)

            result = fout.tell()

            self._pump(f, fout)

            return result

        except (IOError, paramiko.SSHException), e:

            self._translate_io_exception(e, relpath, ': unable to append')

    def rename(self, rel_from, rel_to):

        """Rename without special overwriting"""

        try:

            self._sftp.rename(self._remote_path(rel_from),

                              self._remote_path(rel_to))

        except (IOError, paramiko.SSHException), e:

            self._translate_io_exception(e, rel_from,

                    ': unable to rename to %r' % (rel_to))

    def _rename_and_overwrite(self, abs_from, abs_to):

        """Do a fancy rename on the remote server.

        Using the implementation provided by osutils.

        """

        try:

            fancy_rename(abs_from, abs_to,

                    rename_func=self._sftp.rename,

                    unlink_func=self._sftp.remove)

        except (IOError, paramiko.SSHException), e:

            self._translate_io_exception(e, abs_from, ': unable to rename to %r' % (abs_to))

    def move(self, rel_from, rel_to):

        """Move the item at rel_from to the location at rel_to"""

        path_from = self._remote_path(rel_from)

        path_to = self._remote_path(rel_to)

        self._rename_and_overwrite(path_from, path_to)

    def delete(self, relpath):

        """Delete the item at relpath"""

        path = self._remote_path(relpath)

        try:

            self._sftp.remove(path)

        except (IOError, paramiko.SSHException), e:

            self._translate_io_exception(e, path, ': unable to delete')

    def listable(self):

        """Return True if this store supports listing."""

        return True

    def list_dir(self, relpath):

        """

        Return a list of all files at the given location.

        """

        # does anything actually use this?

        path = self._remote_path(relpath)

        try:

            return self._sftp.listdir(path)

        except (IOError, paramiko.SSHException), e:

            self._translate_io_exception(e, path, ': failed to list_dir')

    def rmdir(self, relpath):

        """See Transport.rmdir."""

        path = self._remote_path(relpath)

        try:

            return self._sftp.rmdir(path)

        except (IOError, paramiko.SSHException), e:

            self._translate_io_exception(e, path, ': failed to rmdir')

    def stat(self, relpath):

        """Return the stat information for a file."""

        path = self._remote_path(relpath)

        try:

            return self._sftp.stat(path)

        except (IOError, paramiko.SSHException), e:

            self._translate_io_exception(e, path, ': unable to stat')

    def lock_read(self, relpath):

        """

        Lock the given file for shared (read) access.

        :return: A lock object, which has an unlock() member function

        """

        # FIXME: there should be something clever i can do here...

        class BogusLock(object):

            def __init__(self, path):

                self.path = path

            def unlock(self):

                pass

        return BogusLock(relpath)

    def lock_write(self, relpath):

        """

        Lock the given file for exclusive (write) access.

        WARNING: many transports do not support this, so trying avoid using it

        :return: A lock object, which has an unlock() member function

        """

        # This is a little bit bogus, but basically, we create a file

        # which should not already exist, and if it does, we assume

        # that there is a lock, and if it doesn't, the we assume

        # that we have taken the lock.

        return SFTPLock(relpath, self)

    def _unparse_url(self, path=None):

        if path is None:

            path = self._path

        path = urllib.quote(path)

        # handle homedir paths

        if not path.startswith('/'):

            path = "/~/" + path

        netloc = urllib.quote(self._host)

        if self._username is not None:

            netloc = '%s@%s' % (urllib.quote(self._username), netloc)

        if self._port is not None:

            netloc = '%s:%d' % (netloc, self._port)

        return urlparse.urlunparse(('sftp', netloc, path, '', '', ''))

    def _split_url(self, url):

        (scheme, username, password, host, port, path) = split_url(url)

        assert scheme == 'sftp'

        # the initial slash should be removed from the path, and treated

        # as a homedir relative path (the path begins with a double slash

        # if it is absolute).

        # see draft-ietf-secsh-scp-sftp-ssh-uri-03.txt

        # RBC 20060118 we are not using this as its too user hostile. instead

        # we are following lftp and using /~/foo to mean '~/foo'.