class BaseSshHandler(object):

    # Protocol for setting properties:

    # Set by sub class:

    #   vcs_type: 'hg' or 'git'

    # Set by make() / __init__():

    #   repo_name: requested repo name - only validated by serve()

    # Set by serve() - must not be accessed before:

    #   db_repo: repository db object

    #   authuser: user that has been authenticated - like request.authuser ... which isn't used here

    #   allow_push: false for read-only access to the repo

    # Set defaults, in case .exit should be called early

    vcs_type = None

    repo_name = None

    @staticmethod

    def make(ssh_command):

        """Factory function. Given a command as invoked over SSH (and preserved

        in SSH_ORIGINAL_COMMAND when run as authorized_keys command), return a

        handler if the command looks ok, else return None.

        """

        raise NotImplementedError

    def __init__(self, repo_name):

    def serve(self, user_id, key_id, client_ip):

        """Verify basic sanity of the repository, and that the user is

        valid and has access - then serve the native VCS protocol for

        repository access."""

        dbuser = User.get(user_id)

        if dbuser is None:

            self.exit('User %r not found' % user_id)

        self.authuser = AuthUser.make(dbuser=dbuser, ip_addr=client_ip)

        log.info('Authorized user %s from SSH %s trusting user id %s and key id %s for %r', dbuser, client_ip, user_id, key_id, self.repo_name)

        if self.authuser is None: # not ok ... but already kind of authenticated by SSH ... but not really not authorized ...

            self.exit('User %s from %s cannot be authorized' % (dbuser.username, client_ip))

        ssh_key = UserSshKeys.get(key_id)

        if ssh_key is None:

            self.exit('SSH key %r not found' % key_id)

        ssh_key.last_seen = datetime.datetime.now()

        Session().commit()

        if HasPermissionAnyMiddleware('repository.write',

                                      'repository.admin')(self.authuser, self.repo_name):

            self.allow_push = True

        elif HasPermissionAnyMiddleware('repository.read')(self.authuser, self.repo_name):

            self.allow_push = False

        clone_url = vt.repo_url_param(webserver, vt.repo_name)

        stdout, stderr = Command(dest_dir).execute(vt.repo_type, 'pull', clone_url)

        if vt.repo_type == 'git':

            assert 'FETCH_HEAD' in stderr

        elif vt.repo_type == 'hg':

            assert 'new changesets' in stdout

        action_parts = [ul.action for ul in UserLog.query().order_by(UserLog.user_log_id)]

        assert action_parts == [u'pull']

        # Test handling of URLs with extra '/' around repo_name

        stdout, stderr = Command(dest_dir).execute(vt.repo_type, 'pull', clone_url.replace('/' + vt.repo_name, '/./%s/' % vt.repo_name), ignoreReturnCode=True)

        if issubclass(vt, HttpVcsTest):

            if vt.repo_type == 'git':

                # NOTE: when pulling from http://hostname/./vcs_test_git/ , the git client will normalize that and issue an HTTP request to /vcs_test_git/info/refs

                assert 'Already up to date.' in stdout

            else:

                assert vt.repo_type == 'hg'

                assert "abort: HTTP Error 404: Not Found" in stderr

        else:

            assert issubclass(vt, SshVcsTest)

            if vt.repo_type == 'git':

            else:

        stdout, stderr = Command(dest_dir).execute(vt.repo_type, 'pull', clone_url.replace('/' + vt.repo_name, '/%s/' % vt.repo_name), ignoreReturnCode=True)

            if vt.repo_type == 'git':

                assert 'Already up to date.' in stdout

            else:

                assert vt.repo_type == 'hg'

                assert "no changes found" in stdout

            assert "denied" not in stderr

            assert "denied" not in stdout

            assert "404" not in stdout

    @parametrize_vcs_test

    def test_push_invalidates_cache(self, webserver, testfork, vt):

        pre_cached_tip = [repo.get_api_data()['last_changeset']['short_id'] for repo in Repository.query().filter(Repository.repo_name == testfork[vt.repo_type])]

        key = CacheInvalidation.query().filter(CacheInvalidation.cache_key

                                               == testfork[vt.repo_type]).scalar()

        if not key:

            key = CacheInvalidation(testfork[vt.repo_type], testfork[vt.repo_type])

            Session().add(key)

        key.cache_active = True

        Session().commit()

        dest_dir = _get_tmp_dir()

        clone_url = vt.repo_url_param(webserver, testfork[vt.repo_type])

        stdout, stderr = Command(TESTS_TMP_PATH).execute(vt.repo_type, 'clone', clone_url, dest_dir)

        stdout, stderr = _add_files_and_push(webserver, vt, dest_dir, files_no=1, clone_url=clone_url)

        if vt.repo_type == 'git':

            _check_proper_git_push(stdout, stderr)

        post_cached_tip = [repo.get_api_data()['last_changeset']['short_id'] for repo in Repository.query().filter(Repository.repo_name == testfork[vt.repo_type])]