Merge remote-tracking branch 'kali/feature/create_bitmask_namespace' into develop

3 files changed, 842 insertions, 0 deletions

diff --git a/src/leap/bitmask/platform_init/__init__.py b/src/leap/bitmask/platform_init/__init__.py
new file mode 100644
index 00000000..2a262a30
--- /dev/null
+++ b/src/leap/bitmask/platform_init/__init__.py
@@ -0,0 +1,28 @@
+# -*- coding: utf-8 -*-
+# __init__.py
+# Copyright (C) 2013 LEAP
+#
+# 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 3 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, see <http://www.gnu.org/licenses/>.
+
+"""
+System constants
+"""
+import platform
+
+_system = platform.system()
+
+IS_WIN = True if _system == "Windows" else False
+IS_MAC = True if _system == "Darwin" else False
+IS_LINUX = True if _system == "Linux" else False
+IS_UNIX = IS_MAC or IS_LINUX
diff --git a/src/leap/bitmask/platform_init/initializers.py b/src/leap/bitmask/platform_init/initializers.py
new file mode 100644
index 00000000..831c6a1c
--- /dev/null
+++ b/src/leap/bitmask/platform_init/initializers.py
@@ -0,0 +1,409 @@
+# -*- coding: utf-8 -*-
+# initializers.py
+# Copyright (C) 2013 LEAP
+#
+# 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 3 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, see <http://www.gnu.org/licenses/>.
+
+"""
+Platform dependant initializing code
+"""
+
+import logging
+import os
+import platform
+import stat
+import subprocess
+import tempfile
+
+from PySide import QtGui
+
+from leap.bitmask.config.leapsettings import LeapSettings
+from leap.bitmask.services.eip import vpnlaunchers
+from leap.bitmask.util import first
+from leap.bitmask.util import privilege_policies
+
+
+logger = logging.getLogger(__name__)
+
+# NOTE we could use a deferToThread here, but should
+# be aware of this bug: http://www.themacaque.com/?p=1067
+
+__all__ = ["init_platform"]
+
+_system = platform.system()
+
+
+def init_platform():
+    """
+    Returns the right initializer for the platform we are running in, or
+    None if no proper initializer is found
+    """
+    initializer = None
+    try:
+        initializer = globals()[_system + "Initializer"]
+    except:
+        pass
+    if initializer:
+        logger.debug("Running initializer for %s" % (platform.system(),))
+        initializer()
+    else:
+        logger.debug("Initializer not found for %s" % (platform.system(),))
+
+
+#
+# common utils
+#
+
+NOTFOUND_MSG = ("Tried to install %s, but %s "
+                "not found inside this bundle.")
+BADEXEC_MSG = ("Tried to install %s, but %s "
+               "failed to %s.")
+
+UPDOWN_NOTFOUND_MSG = NOTFOUND_MSG % (
+    "updown scripts", "those were")
+UPDOWN_BADEXEC_MSG = BADEXEC_MSG % (
+    "updown scripts", "they", "be copied")
+
+
+def get_missing_updown_dialog():
+    """
+    Creates a dialog for notifying of missing updown scripts.
+    Returns that dialog.
+
+    :rtype: QtGui.QMessageBox instance
+    """
+    WE_NEED_POWERS = ("To better protect your privacy, "
+                      "Bitmask needs administrative privileges "
+                      "to install helper files. "
+                      "Do you want to proceed?")
+    msg = QtGui.QMessageBox()
+    msg.setWindowTitle(msg.tr("Missing up/down scripts"))
+    msg.setText(msg.tr(WE_NEED_POWERS))
+    # but maybe the user really deserve to know more
+    #msg.setInformativeText(msg.tr(BECAUSE))
+    msg.setStandardButtons(QtGui.QMessageBox.Yes | QtGui.QMessageBox.No)
+    msg.addButton("No, don't ask again", QtGui.QMessageBox.RejectRole)
+    msg.setDefaultButton(QtGui.QMessageBox.Yes)
+    return msg
+
+
+def check_missing():
+    """
+    Checks for the need of installing missing scripts, and
+    raises a dialog to ask user for permission to do it.
+    """
+    config = LeapSettings()
+    alert_missing = config.get_alert_missing_scripts()
+
+    launcher = vpnlaunchers.get_platform_launcher()
+    missing_scripts = launcher.missing_updown_scripts
+    missing_other = launcher.missing_other_files
+
+    if alert_missing and (missing_scripts() or missing_other()):
+        msg = get_missing_updown_dialog()
+        ret = msg.exec_()
+
+        if ret == QtGui.QMessageBox.Yes:
+            install_missing_fun = globals().get(
+                "_%s_install_missing_scripts" % (_system.lower(),),
+                None)
+            if not install_missing_fun:
+                logger.warning(
+                    "Installer not found for platform %s." % (_system,))
+                return
+
+            # XXX maybe move constants to fun
+            ok = install_missing_fun(UPDOWN_BADEXEC_MSG, UPDOWN_NOTFOUND_MSG)
+            if not ok:
+                msg = QtGui.QMessageBox()
+                msg.setWindowTitle(msg.tr("Problem installing files"))
+                msg.setText(msg.tr('Some of the files could not be copied.'))
+                msg.setIcon(QtGui.QMessageBox.Warning)
+                msg.exec_()
+
+        elif ret == QtGui.QMessageBox.No:
+            logger.debug("Not installing missing scripts, "
+                         "user decided to ignore our warning.")
+
+        elif ret == QtGui.QMessageBox.Rejected:
+            logger.debug(
+                "Setting alert_missing_scripts to False, we will not "
+                "ask again")
+            config.set_alert_missing_scripts(False)
+#
+# windows initializers
+#
+
+
+def _windows_has_tap_device():
+    """
+    Loops over the windows registry trying to find if the tap0901 tap driver
+    has been installed on this machine.
+    """
+    import _winreg as reg
+
+    adapter_key = 'SYSTEM\CurrentControlSet\Control\Class' \
+        '\{4D36E972-E325-11CE-BFC1-08002BE10318}'
+    with reg.OpenKey(reg.HKEY_LOCAL_MACHINE, adapter_key) as adapters:
+        try:
+            for i in xrange(10000):
+                key_name = reg.EnumKey(adapters, i)
+                with reg.OpenKey(adapters, key_name) as adapter:
+                    try:
+                        component_id = reg.QueryValueEx(adapter,
+                                                        'ComponentId')[0]
+                        if component_id.startswith("tap0901"):
+                            return True
+                    except WindowsError:
+                        pass
+        except WindowsError:
+            pass
+    return False
+
+
+def WindowsInitializer():
+    """
+    Raises a dialog in case that the windows tap driver has not been found
+    in the registry, asking the user for permission to install the driver
+    """
+    if not _windows_has_tap_device():
+        msg = QtGui.QMessageBox()
+        msg.setWindowTitle(msg.tr("TAP Driver"))
+        msg.setText(msg.tr("Bitmask needs to install the necessary drivers "
+                           "for Encrypted Internet to work. Would you like to "
+                           "proceed?"))
+        msg.setInformativeText(msg.tr("Encrypted Internet uses VPN, which "
+                                      "needs a TAP device installed and none "
+                                      "has been found. This will ask for "
+                                      "administrative privileges."))
+        msg.setStandardButtons(QtGui.QMessageBox.Yes | QtGui.QMessageBox.No)
+        msg.setDefaultButton(QtGui.QMessageBox.Yes)
+        ret = msg.exec_()
+
+        if ret == QtGui.QMessageBox.Yes:
+            # XXX should do this only if executed inside bundle.
+            # Let's assume it's the only way it's gonna be executed under win
+            # by now.
+            driver_path = os.path.join(os.getcwd(),
+                                       "apps",
+                                       "eip",
+                                       "tap_driver")
+            dev_installer = os.path.join(driver_path,
+                                         "devcon.exe")
+            if os.path.isfile(dev_installer) and \
+                    stat.S_IXUSR & os.stat(dev_installer)[stat.ST_MODE] != 0:
+                inf_path = os.path.join(driver_path,
+                                        "OemWin2k.inf")
+                cmd = [dev_installer, "install", inf_path, "tap0901"]
+                ret = subprocess.call(cmd, stdout=subprocess.PIPE, shell=True)
+            else:
+                logger.error("Tried to install TAP driver, but the installer "
+                             "is not found or not executable")
+
+#
+# Darwin initializer functions
+#
+
+
+def _darwin_has_tun_kext():
+    """
+    Returns True only if we found a directory under the system kext folder
+    containing a kext named tun.kext, AND we found a startup item named 'tun'
+    """
+    # XXX we should be smarter here and use kextstats output.
+
+    has_kext = os.path.isdir("/Library/Extensions/tun.kext")
+    has_startup = os.path.isdir("/Library/StartupItems/tun")
+    has_tun_and_startup = has_kext and has_startup
+    logger.debug(
+        'platform initializer check: has tun_and_startup = %s' %
+        (has_tun_and_startup,))
+    return has_tun_and_startup
+
+
+def _darwin_install_missing_scripts(badexec, notfound):
+    """
+    Tries to install the missing up/down scripts.
+
+    :param badexec: error for notifying execution error during command.
+    :type badexec: str
+    :param notfound: error for notifying missing path.
+    :type notfound: str
+    :returns: True if the files could be copied successfully.
+    :rtype: bool
+    """
+    # We expect to execute this from some way of bundle, since
+    # the up/down scripts should be put in place by the installer.
+    success = False
+    installer_path = os.path.join(
+        os.getcwd(),
+        "..",
+        "Resources",
+        "openvpn")
+    launcher = vpnlaunchers.DarwinVPNLauncher
+
+    if os.path.isdir(installer_path):
+        fd, tempscript = tempfile.mkstemp(prefix="leap_installer-")
+        try:
+            scriptlines = launcher.cmd_for_missing_scripts(installer_path)
+            with os.fdopen(fd, 'w') as f:
+                f.write(scriptlines)
+            st = os.stat(tempscript)
+            os.chmod(tempscript, st.st_mode | stat.S_IEXEC | stat.S_IXUSR |
+                     stat.S_IXGRP | stat.S_IXOTH)
+
+            cmd, args = launcher().get_cocoasudo_installmissing_cmd()
+            args.append(tempscript)
+            cmdline = " ".join([cmd] + args)
+            ret = subprocess.call(
+                cmdline, stdout=subprocess.PIPE,
+                shell=True)
+            success = ret == 0
+            if not success:
+                logger.error("Install missing scripts failed.")
+        except Exception as exc:
+            logger.error(badexec)
+            logger.error("Error was: %r" % (exc,))
+        finally:
+            try:
+                os.remove(tempscript)
+            except OSError as exc:
+                logger.error("%r" % (exc,))
+    else:
+        logger.error(notfound)
+        logger.debug('path searched: %s' % (installer_path,))
+
+    return success
+
+
+def DarwinInitializer():
+    """
+    Raises a dialog in case that the osx tuntap driver has not been found
+    in the registry, asking the user for permission to install the driver
+    """
+    # XXX split this function into several
+
+    TUNTAP_NOTFOUND_MSG = NOTFOUND_MSG % (
+        "tuntaposx kext", "the installer")
+    TUNTAP_BADEXEC_MSG = BADEXEC_MSG % (
+        "tuntaposx kext", "the installer", "be launched")
+
+    # TODO DRY this with other cases, and
+    # factor out to _should_install() function.
+    # Leave the dialog as a more generic thing.
+
+    if not _darwin_has_tun_kext():
+        msg = QtGui.QMessageBox()
+        msg.setWindowTitle(msg.tr("TUN Driver"))
+        msg.setText(msg.tr("Bitmask needs to install the necessary drivers "
+                           "for Encrypted Internet to work. Would you like to "
+                           "proceed?"))
+        msg.setInformativeText(msg.tr("Encrypted Internet uses VPN, which "
+                                      "needs a kernel extension for a TUN "
+                                      "device installed, and none "
+                                      "has been found. This will ask for "
+                                      "administrative privileges."))
+        msg.setStandardButtons(QtGui.QMessageBox.Yes | QtGui.QMessageBox.No)
+        msg.setDefaultButton(QtGui.QMessageBox.Yes)
+        ret = msg.exec_()
+
+        if ret == QtGui.QMessageBox.Yes:
+            installer_path = os.path.abspath(
+                os.path.join(
+                    os.getcwd(),
+                    "..",
+                    "Resources",
+                    "tuntap-installer.app"))
+            if os.path.isdir(installer_path):
+                cmd = ["open '%s'" % (installer_path,)]
+                try:
+                    ret = subprocess.call(
+                        cmd, stdout=subprocess.PIPE,
+                        shell=True)
+                except:
+                    logger.error(TUNTAP_BADEXEC_MSG)
+            else:
+                logger.error(TUNTAP_NOTFOUND_MSG)
+
+    # Second check, for missing scripts.
+    check_missing()
+
+
+#
+# Linux initializers
+#
+def _linux_install_missing_scripts(badexec, notfound):
+    """
+    Tries to install the missing up/down scripts.
+
+    :param badexec: error for notifying execution error during command.
+    :type badexec: str
+    :param notfound: error for notifying missing path.
+    :type notfound: str
+    :returns: True if the files could be copied successfully.
+    :rtype: bool
+    """
+    success = False
+    installer_path = os.path.join(os.getcwd(), "apps", "eip", "files")
+    launcher = vpnlaunchers.LinuxVPNLauncher
+
+    # XXX refactor with darwin, same block.
+
+    if os.path.isdir(installer_path):
+        fd, tempscript = tempfile.mkstemp(prefix="leap_installer-")
+        polfd, pol_tempfile = tempfile.mkstemp(prefix="leap_installer-")
+        try:
+            path = launcher.OPENVPN_BIN_PATH
+            policy_contents = privilege_policies.get_policy_contents(path)
+
+            with os.fdopen(polfd, 'w') as f:
+                f.write(policy_contents)
+
+            pkexec = first(launcher.maybe_pkexec())
+            scriptlines = launcher.cmd_for_missing_scripts(installer_path,
+                                                           pol_tempfile)
+            with os.fdopen(fd, 'w') as f:
+                f.write(scriptlines)
+
+            st = os.stat(tempscript)
+            os.chmod(tempscript, st.st_mode | stat.S_IEXEC | stat.S_IXUSR |
+                     stat.S_IXGRP | stat.S_IXOTH)
+            cmdline = ["%s %s" % (pkexec, tempscript)]
+            ret = subprocess.call(
+                cmdline, stdout=subprocess.PIPE,
+                shell=True)
+            success = ret == 0
+            if not success:
+                logger.error("Install missing scripts failed.")
+        except Exception as exc:
+            logger.error(badexec)
+            logger.error("Error was: %r" % (exc,))
+        finally:
+            try:
+                os.remove(tempscript)
+            except OSError as exc:
+                logger.error("%r" % (exc,))
+    else:
+        logger.error(notfound)
+        logger.debug('path searched: %s' % (installer_path,))
+
+    return success
+
+
+def LinuxInitializer():
+    """
+    Raises a dialog in case that either updown scripts or policykit file
+    are missing or they have incorrect permissions.
+    """
+    check_missing()
diff --git a/src/leap/bitmask/platform_init/locks.py b/src/leap/bitmask/platform_init/locks.py
new file mode 100644
index 00000000..ecfe3b1f
--- /dev/null
+++ b/src/leap/bitmask/platform_init/locks.py
@@ -0,0 +1,405 @@
+# -*- coding: utf-8 -*-
+# locks.py
+# Copyright (C) 2013 LEAP
+#
+# 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 3 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, see <http://www.gnu.org/licenses/>.
+"""
+Utilities for handling multi-platform file locking mechanisms
+"""
+import logging
+import errno
+import os
+import platform
+
+from leap.bitmask import platform_init
+from leap.common.events import signal as signal_event
+from leap.common.events import events_pb2 as proto
+
+if platform_init.IS_UNIX:
+    from fcntl import flock, LOCK_EX, LOCK_NB
+else:  # WINDOWS
+    import datetime
+    import glob
+    import shutil
+    import time
+
+    from tempfile import gettempdir
+
+    from leap.bitmask.util import get_modification_ts, update_modification_ts
+
+logger = logging.getLogger(__name__)
+
+if platform_init.IS_UNIX:
+
+    class UnixLock(object):
+        """
+        Uses flock to get an exclusive lock over a file.
+        See man 2 flock
+        """
+
+        def __init__(self, path):
+            """
+            iniializes t he UnixLock with the path of the
+            desired lockfile
+            """
+
+            self._fd = None
+            self.path = path
+
+        def get_lock(self):
+            """
+            Tries to get a lock, and writes the running pid there if successful
+            """
+            gotit, pid = self._get_lock_and_pid()
+            return gotit
+
+        def get_pid(self):
+            """
+            Returns the pid of the locking process
+            """
+            gotit, pid = self._get_lock_and_pid()
+            return pid
+
+        def _get_lock(self):
+            """
+            Tries to get a lock, returning True if successful
+
+            :rtype: bool
+            """
+            self._fd = os.open(self.path, os.O_CREAT | os.O_RDWR)
+
+            try:
+                flock(self._fd, LOCK_EX | LOCK_NB)
+            except IOError as exc:
+                # could not get the lock
+                #import ipdb; ipdb.set_trace()
+
+                if exc.args[0] in (errno.EDEADLK, errno.EAGAIN):
+                    # errno 11 or 35
+                    # Resource temporarily unavailable
+                    return False
+                else:
+                    raise
+            return True
+
+        @property
+        def locked_by_us(self):
+            """
+            Returns True if the pid in the pidfile
+            is ours.
+
+            :rtype: bool
+            """
+            gotit, pid = self._get_lock_and_pid()
+            return pid == os.getpid()
+
+        def _get_lock_and_pid(self):
+            """
+            Tries to get a lock over the file.
+            Returns (locked, pid) tuple.
+
+            :rtype: tuple
+            """
+
+            if self._get_lock():
+                self._write_to_pidfile()
+                return True, None
+
+            return False, self._read_from_pidfile()
+
+        def _read_from_pidfile(self):
+            """
+            Tries to read pid from the pidfile,
+            returns False if no content found.
+            """
+
+            pidfile = os.read(
+                self._fd, 16)
+            if not pidfile:
+                return False
+
+            try:
+                return int(pidfile.strip())
+            except Exception as exc:
+                exc.args += (pidfile, self.lock_file)
+                raise
+
+        def _write_to_pidfile(self):
+            """
+            Writes the pid of the running process
+            to the pidfile
+            """
+            fd = self._fd
+            os.ftruncate(fd, 0)
+            os.write(fd, '%d\n' % os.getpid())
+            os.fsync(fd)
+
+
+if platform_init.IS_WIN:
+
+    # Time to wait (in secs) before assuming a raise window signal has not been
+    # ack-ed.
+
+    RAISE_WINDOW_TIMEOUT = 2
+
+    # How many steps to do while checking lockfile ts update.
+
+    RAISE_WINDOW_WAIT_STEPS = 10
+
+    def _release_lock(name):
+        """
+        Tries to remove a folder path.
+
+        :param name: folder lock to remove
+        :type name: str
+        """
+        try:
+            shutil.rmtree(name)
+            return True
+        except WindowsError as exc:
+            if exc.errno in (errno.EPIPE, errno.ENOENT,
+                             errno.ESRCH, errno.EACCES):
+                logger.warning(
+                    'exception while trying to remove the lockfile dir')
+                logger.warning('errno %s: %s' % (exc.errno, exc.args[1]))
+                # path does not exist
+                return False
+            else:
+                logger.debug('errno = %s' % (exc.errno,))
+                # we did not foresee this error, better add it explicitely
+                raise
+
+    class WindowsLock(object):
+        """
+        Creates a lock based on the atomic nature of mkdir on Windows
+        system calls.
+        """
+        LOCKBASE = os.path.join(gettempdir(), "leap-client-lock")
+
+        def __init__(self):
+            """
+            Initializes the lock.
+            Sets the lock name to basename plus the process pid.
+            """
+            self._fd = None
+            pid = os.getpid()
+            self.name = "%s-%s" % (self.LOCKBASE, pid)
+            self.pid = pid
+
+        def get_lock(self):
+            """
+            Tries to get a lock, and writes the running pid there if successful
+            """
+            gotit = self._get_lock()
+            return gotit
+
+        def _get_lock(self):
+            """
+            Tries to write to a file with the current pid as part of the name
+            """
+            try:
+                self._fd = os.makedirs(self.name)
+            except OSError as exc:
+                # could not create the dir
+                if exc.args[0] == 183:
+                    logger.debug('cannot create dir')
+                    # cannot create dir with existing name
+                    return False
+                else:
+                    raise
+            return self._is_one_pidfile()[0]
+
+        def _is_one_pidfile(self):
+            """
+            Returns True, pid if there is only one pidfile with the expected
+            base path
+
+            :rtype: tuple
+            """
+            pidfiles = glob.glob(self.LOCKBASE + '-*')
+            if len(pidfiles) == 1:
+                pid = pidfiles[0].split('-')[-1]
+                return True, int(pid)
+            else:
+                return False, None
+
+        def get_pid(self):
+            """
+            Returns the pid of the locking process.
+
+            :rtype: int
+            """
+            # XXX assert there is only one?
+            _, pid = self._is_one_pidfile()
+            return pid
+
+        def get_locking_path(self):
+            """
+            Returns the pid path of the locking process.
+
+            :rtype: str
+            """
+            pid = self.get_pid()
+            if pid:
+                return "%s-%s" % (self.LOCKBASE, pid)
+
+        def release_lock(self, name=None):
+            """
+            Releases the pidfile dir for this process, by removing it.
+            """
+            if not name:
+                name = self.name
+            _release_lock(name)
+
+        @classmethod
+        def release_all_locks(self):
+            """
+            Releases all locks. Used for clean shutdown.
+            """
+            for lockdir in glob.glob("%s-%s" % (self.LOCKBASE, '*')):
+                _release_lock(lockdir)
+
+        @property
+        def locked_by_us(self):
+            """
+            Returns True if the pid in the pidfile
+            is ours.
+
+            :rtype: bool
+            """
+            _, pid = self._is_one_pidfile()
+            return pid == self.pid
+
+        def update_ts(self):
+            """
+            Updates the timestamp of the lock.
+            """
+            if self.locked_by_us:
+                update_modification_ts(self.name)
+
+        def write_port(self, port):
+            """
+            Writes the port for windows control to the pidfile folder
+            Returns True if successful.
+
+            :rtype: bool
+            """
+            if not self.locked_by_us:
+                logger.warning("Tried to write control port to a "
+                               "non-unique pidfile folder")
+                return False
+            port_file = os.path.join(self.name, "port")
+            with open(port_file, 'w') as f:
+                f.write("%s" % port)
+            return True
+
+        def get_control_port(self):
+            """
+            Reads control port of the main instance from the port file
+            in the pidfile dir
+
+            :rtype: int
+            """
+            pid = self.get_pid()
+            port_file = os.path.join(self.LOCKBASE + "-%s" % pid, "port")
+            port = None
+            try:
+                with open(port_file) as f:
+                    port_str = f.read()
+                    port = int(port_str.strip())
+            except IOError as exc:
+                if exc.errno == errno.ENOENT:
+                    logger.error("Tried to read port from non-existent file")
+                else:
+                    # we did not know explicitely about this error
+                    raise
+            return port
+
+    def raise_window_ack():
+        """
+        This function is called from the windows callback that is registered
+        with the raise_window event. It just updates the modification time
+        of the lock file so we can signal an ack to the instance that tried
+        to raise the window.
+        """
+        lock = WindowsLock()
+        lock.update_ts()
+
+
+def we_are_the_one_and_only():
+    """
+    Returns True if we are the only instance running, False otherwise.
+    If we came later, send a raise signal to the main instance of the
+    application.
+
+    Under windows we are not using flock magic, so we wait during
+    RAISE_WINDOW_TIMEOUT time, if not ack is
+    received, we assume it was a stalled lock, so we remove it and continue
+    with initialization.
+
+    :rtype: bool
+    """
+    _sys = platform.system()
+
+    if _sys in ("Linux", "Darwin"):
+        locker = UnixLock('/tmp/leap-client.lock')
+        locker.get_lock()
+        we_are_the_one = locker.locked_by_us
+        if not we_are_the_one:
+            signal_event(proto.RAISE_WINDOW)
+        return we_are_the_one
+
+    elif _sys == "Windows":
+        locker = WindowsLock()
+        locker.get_lock()
+        we_are_the_one = locker.locked_by_us
+
+        if not we_are_the_one:
+            locker.release_lock()
+        lock_path = locker.get_locking_path()
+        ts = get_modification_ts(lock_path)
+
+        nowfun = datetime.datetime.now
+        t0 = nowfun()
+        pause = RAISE_WINDOW_TIMEOUT / float(RAISE_WINDOW_WAIT_STEPS)
+        timeout_delta = datetime.timedelta(0, RAISE_WINDOW_TIMEOUT)
+        check_interval = lambda: nowfun() - t0 < timeout_delta
+
+        # let's assume it's a stalled lock
+        we_are_the_one = True
+        signal_event(proto.RAISE_WINDOW)
+
+        while check_interval():
+            if get_modification_ts(lock_path) > ts:
+                # yay! someone claimed their control over the lock.
+                # so the lock is alive
+                logger.debug('Raise window ACK-ed')
+                we_are_the_one = False
+                break
+            else:
+                time.sleep(pause)
+
+        if we_are_the_one:
+            # ok, it really was a stalled lock. let's remove all
+            # that is left, and put only ours there.
+            WindowsLock.release_all_locks()
+            WindowsLock().get_lock()
+
+        return we_are_the_one
+
+    else:
+        logger.warning("Multi-instance checker "
+                       "not implemented for %s" % (_sys))
+        # lies, lies, lies...
+        return True