~bzr-pqm/bzr/bzr.dev

# Copyright (C) 2005 Robey Pointer <robey@lag.net>, 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 re
import stat
import sys
import urllib
import time
import random

from bzrlib.errors import (FileExists, 
                           TransportNotPossible, NoSuchFile, NonRelativePath,
                           TransportError,
                           LockError)
from bzrlib.config import config_dir
from bzrlib.trace import mutter, warning, error
from bzrlib.transport import Transport, register_transport

try:
    import paramiko
except ImportError:
    error('The SFTP transport requires paramiko.')
    raise
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


SYSTEM_HOSTKEYS = {}
BZR_HOSTKEYS = {}

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 = os.path.join(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 = os.path.join(config_dir(), 'ssh_host_keys')
    if not os.path.isdir(config_dir()):
        os.mkdir(config_dir())
    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 SFTPTransportError (TransportError):
    pass

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:
            self.lock_file = transport._sftp_open_exclusive(self.lock_path)
        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:
            warn("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.
    """

    _url_matcher = re.compile(r'^sftp://([^:@]*(:[^@]*)?@)?(.*?)(:[^/]+)?(/.*)?$')
    
    def __init__(self, base, clone_from=None):
        assert base.startswith('sftp://')
        super(SFTPTransport, self).__init__(base)
        self._parse_url(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._abspath(relpath))
    
    def _abspath(self, relpath):
        """Return the absolute path segment without the SFTP URL."""
        # FIXME: share the common code across transports
        assert isinstance(relpath, basestring)
        relpath = [urllib.unquote(relpath)]
        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)
        # could still be a "relative" path here, but relative on the sftp server
        return path

    def relpath(self, abspath):
        # FIXME: this is identical to HttpTransport -- share it
        m = self._url_matcher.match(abspath)
        path = m.group(5)
        if not path.startswith(self._path):
            raise NonRelativePath('path %r is not under base URL %r'
                           % (abspath, self.base))
        pl = len(self.base)
        return abspath[pl:].lstrip('/')

    def has(self, relpath):
        """
        Does the target location exist?
        """
        try:
            self._sftp.stat(self._abspath(relpath))
            return True
        except IOError:
            return False

    def get(self, relpath, decode=False):
        """
        Get the file at the given relative path.

        :param relpath: The relative path to the file
        """
        try:
            path = self._abspath(relpath)
            f = self._sftp.file(path)
            try:
                f.prefetch()
            except AttributeError:
                # only works on paramiko 1.5.1 or greater
                pass
            return f
        except (IOError, paramiko.SSHException), x:
            raise NoSuchFile('Error retrieving %s: %s' % (path, str(x)), x)

    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)
        try:
            f.prefetch()
        except AttributeError:
            # only works on paramiko 1.5.1 or greater
            pass
        return f

    def put(self, relpath, f):
        """
        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.
        """
        final_path = self._abspath(relpath)
        tmp_relpath = '%s.tmp.%.9f.%d.%d' % (relpath, time.time(),
                        os.getpid(), random.randint(0,0x7FFFFFFF))
        tmp_abspath = self._abspath(tmp_relpath)
        fout = self._sftp_open_exclusive(tmp_relpath)

        try:
            try:
                self._pump(f, fout)
            except IOError, e:
                self._translate_io_exception(e, relpath)
            except paramiko.SSHException, x:
                raise SFTPTransportError('Unable to write file %r' % (path,), x)
        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
            try:
                fout.close()
                self._sftp.remove(tmp_abspath)
            except:
                pass
            raise e
        else:
            # sftp rename doesn't allow overwriting, so play tricks:
            tmp_safety = 'bzr.tmp.%.9f.%d.%d' % (time.time(), os.getpid(), random.randint(0, 0x7FFFFFFF))
            tmp_safety = self._abspath(tmp_safety)
            try:
                self._sftp.rename(final_path, tmp_safety)
                file_existed = True
            except:
                file_existed = False
            try:
                self._sftp.rename(tmp_abspath, final_path)
            except IOError, e:
                self._translate_io_exception(e, relpath)
            except paramiko.SSHException, x:
                raise SFTPTransportError('Unable to rename into file %r' 
                                          % (path,), x)
            if file_existed:
                self._sftp.unlink(tmp_safety)

    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):
        """Create a directory at the given path."""
        try:
            path = self._abspath(relpath)
            self._sftp.mkdir(path)
        except IOError, e:
            self._translate_io_exception(e, relpath)
        except (IOError, paramiko.SSHException), x:
            raise SFTPTransportError('Unable to mkdir %r' % (path,), x)

    def _translate_io_exception(self, e, relpath):
        # paramiko seems to generate detailless errors.
        if (e.errno == errno.ENOENT or
            e.args == ('No such file or directory',) or
            e.args == ('No such file',)):
            raise NoSuchFile(relpath)
        if (e.args == ('mkdir failed',)):
            raise FileExists(relpath)
        # strange but true, for the paramiko server.
        if (e.args == ('Failure',)):
            raise FileExists(relpath)
        raise

    def append(self, relpath, f):
        """
        Append the text in the file-like object into the final
        location.
        """
        try:
            path = self._abspath(relpath)
            fout = self._sftp.file(path, 'ab')
            self._pump(f, fout)
        except (IOError, paramiko.SSHException), x:
            raise SFTPTransportError('Unable to append file %r' % (path,), x)

    def copy(self, rel_from, rel_to):
        """Copy the item at rel_from to the location at rel_to"""
        path_from = self._abspath(rel_from)
        path_to = self._abspath(rel_to)
        try:
            fin = self._sftp.file(path_from, 'rb')
            try:
                fout = self._sftp.file(path_to, 'wb')
                try:
                    fout.set_pipelined(True)
                    self._pump(fin, fout)
                finally:
                    fout.close()
            finally:
                fin.close()
        except (IOError, paramiko.SSHException), x:
            raise SFTPTransportError('Unable to copy %r to %r' % (path_from, path_to), x)

    def move(self, rel_from, rel_to):
        """Move the item at rel_from to the location at rel_to"""
        path_from = self._abspath(rel_from)
        path_to = self._abspath(rel_to)
        try:
            self._sftp.rename(path_from, path_to)
        except (IOError, paramiko.SSHException), x:
            raise SFTPTransportError('Unable to move %r to %r' % (path_from, path_to), x)

    def delete(self, relpath):
        """Delete the item at relpath"""
        path = self._abspath(relpath)
        try:
            self._sftp.remove(path)
        except (IOError, paramiko.SSHException), x:
            raise SFTPTransportError('Unable to delete %r' % (path,), x)
            
    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._abspath(relpath)
        try:
            return self._sftp.listdir(path)
        except (IOError, paramiko.SSHException), x:
            raise SFTPTransportError('Unable to list folder %r' % (path,), x)

    def stat(self, relpath):
        """Return the stat information for a file."""
        path = self._abspath(relpath)
        try:
            return self._sftp.stat(path)
        except (IOError, paramiko.SSHException), x:
            raise SFTPTransportError('Unable to stat %r' % (path,), x)

    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
        host = self._host
        username = urllib.quote(self._username)
        if self._password:
            username += ':' + urllib.quote(self._password)
        if self._port != 22:
            host += ':%d' % self._port
        return 'sftp://%s@%s/%s' % (username, host, urllib.quote(path))

    def _parse_url(self, url):
        assert url[:7] == 'sftp://'
        m = self._url_matcher.match(url)
        if m is None:
            raise SFTPTransportError('Unable to parse SFTP URL %r' % (url,))
        self._username, self._password, self._host, self._port, self._path = m.groups()
        if self._username is None:
            self._username = getpass.getuser()
        else:
            if self._password:
                # username field is 'user:pass@' in this case, and password is ':pass'
                username_len = len(self._username) - len(self._password) - 1
                self._username = urllib.unquote(self._username[:username_len])
                self._password = urllib.unquote(self._password[1:])
            else:
                self._username = urllib.unquote(self._username[:-1])
        if self._port is None:
            self._port = 22
        else:
            self._port = int(self._port[1:])
        if (self._path is None) or (self._path == ''):
            self._path = ''
        else:
            # remove leading '/'
            self._path = urllib.unquote(self._path[1:])

    def _sftp_connect(self):
        global SYSTEM_HOSTKEYS, BZR_HOSTKEYS
        
        load_host_keys()
        
        try:
            t = paramiko.Transport((self._host, self._port))
            t.start_client()
        except paramiko.SSHException:
            raise SFTPTransportError('Unable to reach SSH host %s:%d' % (self._host, self._port))
            
        server_key = t.get_remote_server_key()
        server_key_hex = paramiko.util.hexify(server_key.get_fingerprint())
        keytype = server_key.get_name()
        if SYSTEM_HOSTKEYS.has_key(self._host) and SYSTEM_HOSTKEYS[self._host].has_key(keytype):
            our_server_key = SYSTEM_HOSTKEYS[self._host][keytype]
            our_server_key_hex = paramiko.util.hexify(our_server_key.get_fingerprint())
        elif BZR_HOSTKEYS.has_key(self._host) and BZR_HOSTKEYS[self._host].has_key(keytype):
            our_server_key = BZR_HOSTKEYS[self._host][keytype]
            our_server_key_hex = paramiko.util.hexify(our_server_key.get_fingerprint())
        else:
            warning('Adding %s host key for %s: %s' % (keytype, self._host, server_key_hex))
            if not BZR_HOSTKEYS.has_key(self._host):
                BZR_HOSTKEYS[self._host] = {}
            BZR_HOSTKEYS[self._host][keytype] = server_key
            our_server_key = server_key
            our_server_key_hex = paramiko.util.hexify(our_server_key.get_fingerprint())
            save_host_keys()
        if server_key != our_server_key:
            filename1 = os.path.expanduser('~/.ssh/known_hosts')
            filename2 = os.path.join(config_dir(), 'ssh_host_keys')
            raise SFTPTransportError('Host keys for %s do not match!  %s != %s' % \
                (self._host, our_server_key_hex, server_key_hex),
                ['Try editing %s or %s' % (filename1, filename2)])

        self._sftp_auth(t, self._username, self._host)
        
        try:
            self._sftp = t.open_sftp_client()
        except paramiko.SSHException:
            raise BzrError('Unable to find path %s on SFTP server %s' % \
                (self._path, self._host))

    def _sftp_auth(self, transport, username, host):
        agent = paramiko.Agent()
        for key in agent.get_keys():
            mutter('Trying SSH agent key %s' % paramiko.util.hexify(key.get_fingerprint()))
            try:
                transport.auth_publickey(self._username, key)
                return
            except paramiko.SSHException, e:
                pass
        
        # okay, try finding id_rsa or id_dss?  (posix only)
        if self._try_pkey_auth(transport, paramiko.RSAKey, 'id_rsa'):
            return
        if self._try_pkey_auth(transport, paramiko.DSSKey, 'id_dsa'):
            return

        if self._password:
            try:
                transport.auth_password(self._username, self._password)
                return
            except paramiko.SSHException, e:
                pass

        # give up and ask for a password
        # FIXME: shouldn't be implementing UI this deep into bzrlib
        enc = sys.stdout.encoding
        password = getpass.getpass('SSH %s@%s password: ' %
            (self._username.encode(enc, 'replace'), self._host.encode(enc, 'replace')))
        try:
            transport.auth_password(self._username, password)
        except paramiko.SSHException:
            raise SFTPTransportError('Unable to authenticate to SSH host as %s@%s' % \
                (self._username, self._host))

    def _try_pkey_auth(self, transport, pkey_class, filename):
        filename = os.path.expanduser('~/.ssh/' + filename)
        try:
            key = pkey_class.from_private_key_file(filename)
            transport.auth_publickey(self._username, key)
            return True
        except paramiko.PasswordRequiredException:
            # FIXME: shouldn't be implementing UI this deep into bzrlib
            enc = sys.stdout.encoding
            password = getpass.getpass('SSH %s password: ' % 
                (os.path.basename(filename).encode(enc, 'replace'),))
            try:
                key = pkey_class.from_private_key_file(filename, password)
                transport.auth_publickey(self._username, key)
                return True
            except paramiko.SSHException:
                mutter('SSH authentication via %s key failed.' % (os.path.basename(filename),))
        except paramiko.SSHException:
            mutter('SSH authentication via %s key failed.' % (os.path.basename(filename),))
        except IOError:
            pass
        return False

    def _sftp_open_exclusive(self, relpath):
        """Open a remote path exclusively.

        SFTP supports O_EXCL (SFTP_FLAG_EXCL), which fails if
        the file already exists. However it does not expose this
        at the higher level of SFTPClient.open(), so we have to
        sneak away with it.

        WARNING: This breaks the SFTPClient abstraction, so it
        could easily break against an updated version of paramiko.

        :param relpath: The relative path, where the file should be opened
        """
        path = self._abspath(relpath)
        attr = SFTPAttributes()
        mode = (SFTP_FLAG_WRITE | SFTP_FLAG_CREATE 
                | SFTP_FLAG_TRUNC | SFTP_FLAG_EXCL)
        try:
            t, msg = self._sftp._request(CMD_OPEN, path, mode, attr)
            if t != CMD_HANDLE:
                raise SFTPTransportError('Expected an SFTP handle')
            handle = msg.get_string()
            return SFTPFile(self._sftp, handle, 'w', -1)
        except IOError, e:
            self._translate_io_exception(e, relpath)
        except paramiko.SSHException, x:
            raise SFTPTransportError('Unable to open file %r' % (path,), x)