[feature] privileged bitmask helper

This is still quite untested, and a bit hacky, but the main idea behind
let us have a daemonized bitmask helper, that should be installed by the
Bitmask installer. Its responsibilities are to launch the vpn process as
a privileged user, and start/stop the firewall.

1 files changed, 324 insertions, 0 deletions

diff --git a/pkg/osx/runner.py b/pkg/osx/runner.py
new file mode 100644
index 00000000..6973cf1c
--- /dev/null
+++ b/pkg/osx/runner.py
@@ -0,0 +1,324 @@
+# -*- coding: utf-8 -*-
+
+# daemon/runner.py
+# Part of ‘python-daemon’, an implementation of PEP 3143.
+#
+# Copyright © 2009–2015 Ben Finney <ben+python@benfinney.id.au>
+# Copyright © 2007–2008 Robert Niederreiter, Jens Klein
+# Copyright © 2003 Clark Evans
+# Copyright © 2002 Noah Spurrier
+# Copyright © 2001 Jürgen Hermann
+#
+# This is free software: you may copy, modify, and/or distribute this work
+# under the terms of the Apache License, version 2.0 as published by the
+# Apache Software Foundation.
+# No warranty expressed or implied. See the file ‘LICENSE.ASF-2’ for details.
+
+""" Daemon runner library.
+    """
+
+from __future__ import (absolute_import, unicode_literals)
+
+import sys
+import os
+import signal
+import errno
+try:
+    # Python 3 standard library.
+    ProcessLookupError
+except NameError:
+    # No such class in Python 2.
+    ProcessLookupError = NotImplemented
+
+import lockfile
+
+from . import pidfile
+from .daemon import (basestring, unicode)
+from .daemon import DaemonContext
+from .daemon import _chain_exception_from_existing_exception_context
+
+
+class DaemonRunnerError(Exception):
+    """ Abstract base class for errors from DaemonRunner. """
+
+    def __init__(self, *args, **kwargs):
+        self._chain_from_context()
+
+        super(DaemonRunnerError, self).__init__(*args, **kwargs)
+
+    def _chain_from_context(self):
+        _chain_exception_from_existing_exception_context(self, as_cause=True)
+
+
+class DaemonRunnerInvalidActionError(DaemonRunnerError, ValueError):
+    """ Raised when specified action for DaemonRunner is invalid. """
+
+    def _chain_from_context(self):
+        # This exception is normally not caused by another.
+        _chain_exception_from_existing_exception_context(self, as_cause=False)
+
+
+class DaemonRunnerStartFailureError(DaemonRunnerError, RuntimeError):
+    """ Raised when failure starting DaemonRunner. """
+
+
+class DaemonRunnerStopFailureError(DaemonRunnerError, RuntimeError):
+    """ Raised when failure stopping DaemonRunner. """
+
+
+class DaemonRunner:
+    """ Controller for a callable running in a separate background process.
+
+        The first command-line argument is the action to take:
+
+        * 'start': Become a daemon and call `app.run()`.
+        * 'stop': Exit the daemon process specified in the PID file.
+        * 'restart': Stop, then start.
+
+        """
+
+    __metaclass__ = type
+
+    start_message = "started with pid {pid:d}"
+
+    def __init__(self, app):
+        """ Set up the parameters of a new runner.
+
+            :param app: The application instance; see below.
+            :return: ``None``.
+
+            The `app` argument must have the following attributes:
+
+            * `stdin_path`, `stdout_path`, `stderr_path`: Filesystem paths
+              to open and replace the existing `sys.stdin`, `sys.stdout`,
+              `sys.stderr`.
+
+            * `pidfile_path`: Absolute filesystem path to a file that will
+              be used as the PID file for the daemon. If ``None``, no PID
+              file will be used.
+
+            * `pidfile_timeout`: Used as the default acquisition timeout
+              value supplied to the runner's PID lock file.
+
+            * `run`: Callable that will be invoked when the daemon is
+              started.
+
+            """
+        self.parse_args()
+        self.app = app
+        self.daemon_context = DaemonContext()
+        self.daemon_context.stdin = open(app.stdin_path, 'rt')
+        self.daemon_context.stdout = open(app.stdout_path, 'w+t')
+        self.daemon_context.stderr = open(
+                app.stderr_path, 'w+t', buffering=0)
+
+        self.pidfile = None
+        if app.pidfile_path is not None:
+            self.pidfile = make_pidlockfile(
+                    app.pidfile_path, app.pidfile_timeout)
+        self.daemon_context.pidfile = self.pidfile
+
+    def _usage_exit(self, argv):
+        """ Emit a usage message, then exit.
+
+            :param argv: The command-line arguments used to invoke the
+                program, as a sequence of strings.
+            :return: ``None``.
+
+            """
+        progname = os.path.basename(argv[0])
+        usage_exit_code = 2
+        action_usage = "|".join(self.action_funcs.keys())
+        message = "usage: {progname} {usage}".format(
+                progname=progname, usage=action_usage)
+        emit_message(message)
+        sys.exit(usage_exit_code)
+
+    def parse_args(self, argv=None):
+        """ Parse command-line arguments.
+
+            :param argv: The command-line arguments used to invoke the
+                program, as a sequence of strings.
+
+            :return: ``None``.
+
+            The parser expects the first argument as the program name, the
+            second argument as the action to perform.
+
+            If the parser fails to parse the arguments, emit a usage
+            message and exit the program.
+
+            """
+        if argv is None:
+            argv = sys.argv
+
+        min_args = 2
+        if len(argv) < min_args:
+            self._usage_exit(argv)
+
+        self.action = unicode(argv[1])
+        if self.action not in self.action_funcs:
+            self._usage_exit(argv)
+
+    def _start(self):
+        """ Open the daemon context and run the application.
+
+            :return: ``None``.
+            :raises DaemonRunnerStartFailureError: If the PID file cannot
+                be locked by this process.
+
+            """
+        if is_pidfile_stale(self.pidfile):
+            self.pidfile.break_lock()
+
+        try:
+            self.daemon_context.open()
+        except lockfile.AlreadyLocked:
+            error = DaemonRunnerStartFailureError(
+                    "PID file {pidfile.path!r} already locked".format(
+                        pidfile=self.pidfile))
+            raise error
+
+        pid = os.getpid()
+        message = self.start_message.format(pid=pid)
+        emit_message(message)
+
+        self.app.run()
+
+    def _terminate_daemon_process(self):
+        """ Terminate the daemon process specified in the current PID file.
+
+            :return: ``None``.
+            :raises DaemonRunnerStopFailureError: If terminating the daemon
+                fails with an OS error.
+
+            """
+        pid = self.pidfile.read_pid()
+        try:
+            os.kill(pid, signal.SIGTERM)
+        except OSError as exc:
+            error = DaemonRunnerStopFailureError(
+                    "Failed to terminate {pid:d}: {exc}".format(
+                        pid=pid, exc=exc))
+            raise error
+
+    def _stop(self):
+        """ Exit the daemon process specified in the current PID file.
+
+            :return: ``None``.
+            :raises DaemonRunnerStopFailureError: If the PID file is not
+                already locked.
+
+            """
+        if not self.pidfile.is_locked():
+            error = DaemonRunnerStopFailureError(
+                    "PID file {pidfile.path!r} not locked".format(
+                        pidfile=self.pidfile))
+            raise error
+
+        if is_pidfile_stale(self.pidfile):
+            self.pidfile.break_lock()
+        else:
+            self._terminate_daemon_process()
+
+    def _restart(self):
+        """ Stop, then start.
+            """
+        self._stop()
+        self._start()
+
+    action_funcs = {
+            'start': _start,
+            'stop': _stop,
+            'restart': _restart,
+            }
+
+    def _get_action_func(self):
+        """ Get the function for the specified action.
+
+            :return: The function object corresponding to the specified
+                action.
+            :raises DaemonRunnerInvalidActionError: if the action is
+               unknown.
+
+            The action is specified by the `action` attribute, which is set
+            during `parse_args`.
+
+            """
+        try:
+            func = self.action_funcs[self.action]
+        except KeyError:
+            error = DaemonRunnerInvalidActionError(
+                    "Unknown action: {action!r}".format(
+                        action=self.action))
+            raise error
+        return func
+
+    def do_action(self):
+        """ Perform the requested action.
+
+            :return: ``None``.
+
+            The action is specified by the `action` attribute, which is set
+            during `parse_args`.
+
+            """
+        func = self._get_action_func()
+        func(self)
+
+
+def emit_message(message, stream=None):
+    """ Emit a message to the specified stream (default `sys.stderr`). """
+    if stream is None:
+        stream = sys.stderr
+    stream.write("{message}\n".format(message=message))
+    stream.flush()
+
+
+def make_pidlockfile(path, acquire_timeout):
+    """ Make a PIDLockFile instance with the given filesystem path. """
+    if not isinstance(path, basestring):
+        error = ValueError("Not a filesystem path: {path!r}".format(
+                path=path))
+        raise error
+    if not os.path.isabs(path):
+        error = ValueError("Not an absolute path: {path!r}".format(
+                path=path))
+        raise error
+    lockfile = pidfile.TimeoutPIDLockFile(path, acquire_timeout)
+
+    return lockfile
+
+
+def is_pidfile_stale(pidfile):
+    """ Determine whether a PID file is stale.
+
+        :return: ``True`` iff the PID file is stale; otherwise ``False``.
+
+        The PID file is “stale” if its contents are valid but do not
+        match the PID of a currently-running process.
+
+        """
+    result = False
+
+    pidfile_pid = pidfile.read_pid()
+    if pidfile_pid is not None:
+        try:
+            os.kill(pidfile_pid, signal.SIG_DFL)
+        except ProcessLookupError:
+            # The specified PID does not exist.
+            result = True
+        except OSError as exc:
+            if exc.errno == errno.ESRCH:
+                # Under Python 2, process lookup error is an OSError.
+                # The specified PID does not exist.
+                result = True
+
+    return result
+
+
+# Local variables:
+# coding: utf-8
+# mode: python
+# End:
+# vim: fileencoding=utf-8 filetype=python :