#

# Copyright (C) 2013  Red Hat, Inc.

#

# This copyrighted material is made available to anyone wishing to use,

# modify, copy, or redistribute it subject to the terms and conditions of

# the GNU General Public License v.2, or (at your option) any later version.

# This program is distributed in the hope that it will be useful, but WITHOUT

# ANY WARRANTY expressed or implied, including the implied warranties 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., 51 Franklin Street, Fifth Floor, Boston, MA

# 02110-1301, USA.  Any Red Hat trademarks that are incorporated in the

# source code or documentation are not subject to the GNU General Public

# License and may only be used or replicated with the express permission of

# Red Hat, Inc.

#

# Red Hat Author(s): Vratislav Podzimek <vpodzime@redhat.com>

#

"""

Module with various classes and functions needed by the OSCAP addon that are

not specific to any installation mode (tui, gui, ks).

"""

import os

import tempfile

import subprocess

import zipfile

import tarfile

import cpioarchive

import re

import logging

from collections import namedtuple

import gettext

from functools import wraps

from pyanaconda.core import constants

from pyanaconda.modules.common.constants.services import NETWORK

from pyanaconda.threading import threadMgr, AnacondaThread

from org_fedora_oscap import utils

from org_fedora_oscap.data_fetch import fetch_data

log = logging.getLogger("anaconda")

# mimick pyanaconda/core/i18n.py

def _(string):

    if string:

        return gettext.translation("oscap-anaconda-addon", fallback=True).gettext(string)

    else:

        return ""

def N_(string): return string

# everything else should be private

__all__ = ["run_oscap_remediate", "get_fix_rules_pre",

           "wait_and_fetch_net_data", "extract_data", "strip_content_dir",

           "OSCAPaddonError"]

INSTALLATION_CONTENT_DIR = "/tmp/openscap_data/"

TARGET_CONTENT_DIR = "/root/openscap_data/"

SSG_DIR = "/usr/share/xml/scap/ssg/content/"

SSG_CONTENT = "ssg-rhel7-ds.xml"

if constants.shortProductName != 'anaconda':

    if constants.shortProductName == 'fedora':

        SSG_CONTENT  = "ssg-fedora-ds.xml"

    else:

        SSG_CONTENT = "ssg-%s%s-ds.xml" % (constants.shortProductName,

                                            constants.productVersion.strip(".")[0])

RESULTS_PATH = utils.join_paths(TARGET_CONTENT_DIR,

                                "eval_remediate_results.xml")

REPORT_PATH = utils.join_paths(TARGET_CONTENT_DIR,

                               "eval_remediate_report.html")

PRE_INSTALL_FIX_SYSTEM_ATTR = "urn:redhat:anaconda:pre"

THREAD_FETCH_DATA = "AnaOSCAPdataFetchThread"

SUPPORTED_ARCHIVES = (".zip", ".tar", ".tar.gz", ".tar.bz2", )

# buffer size for reading and writing out data (in bytes)

IO_BUF_SIZE = 2 * 1024 * 1024

class OSCAPaddonError(Exception):

    """Exception class for OSCAP addon related errors."""

    pass

class OSCAPaddonNetworkError(OSCAPaddonError):

    """Exception class for OSCAP addon related network errors."""

    pass

class ExtractionError(OSCAPaddonError):

    """Exception class for the extraction errors."""

    pass

MESSAGE_TYPE_FATAL = 0

MESSAGE_TYPE_WARNING = 1

MESSAGE_TYPE_INFO = 2

# namedtuple for messages returned from the rules evaluation

#   origin -- class (inherited from RuleHandler) that generated the message

#   type -- one of the MESSAGE_TYPE_* constants defined above

#   text -- the actual message that should be displayed, logged, ...

RuleMessage = namedtuple("RuleMessage", ["origin", "type", "text"])

class SubprocessLauncher(object):

    def __init__(self, args):

        self.args = args

        self.stdout = ""

        self.stderr = ""

        self.messages = []

        self.returncode = None

    def execute(self, ** kwargs):

        try:

            proc = subprocess.Popen(self.args, stdout=subprocess.PIPE,

                                    stderr=subprocess.PIPE, ** kwargs)

        except OSError as oserr:

            msg = "Failed to run the oscap tool: %s" % oserr

            raise OSCAPaddonError(msg)

        (stdout, stderr) = proc.communicate()

        self.stdout = stdout.decode()

        self.stderr = stderr.decode(errors="replace")

        self.messages = re.findall(r'OpenSCAP Error:.*', self.stderr)

        self.messages = self.messages + re.findall(r'E: oscap:.*', self.stderr)

        self.returncode = proc.returncode

    def log_messages(self):

        for message in self.messages:

            log.warning("OSCAP addon: " + message)

def get_fix_rules_pre(profile, fpath, ds_id="", xccdf_id="", tailoring=""):

    """

    Get fix rules for the pre-installation environment for a given profile in a

    given datastream and checklist in a given file.

    :see: run_oscap_remediate

    :see: _run_oscap_gen_fix

    :return: fix rules for a given profile

    :rtype: str

    """

    return _run_oscap_gen_fix(profile, fpath, PRE_INSTALL_FIX_SYSTEM_ATTR,

                              ds_id=ds_id, xccdf_id=xccdf_id,

                              tailoring=tailoring)

def _run_oscap_gen_fix(profile, fpath, template, ds_id="", xccdf_id="",

                       tailoring=""):

    """

    Run oscap tool on a given file to get the contents of fix elements with the

    'system' attribute equal to a given template for a given datastream,

    checklist and profile.

    :see: run_oscap_remediate

    :param template: the value of the 'system' attribute of the fix elements

    :type template: str

    :return: oscap tool's stdout

    :rtype: str

    """

    if not profile:

        return ""

    args = ["oscap", "xccdf", "generate", "fix"]

    args.append("--template=%s" % template)

    # oscap uses the default profile by default

    if profile.lower() != "default":

        args.append("--profile=%s" % profile)

    if ds_id:

        args.append("--datastream-id=%s" % ds_id)

    if xccdf_id:

        args.append("--xccdf-id=%s" % xccdf_id)

    if tailoring:

        args.append("--tailoring-file=%s" % tailoring)

    args.append(fpath)

    proc = SubprocessLauncher(args)

    proc.execute()

    proc.log_messages()

    if proc.returncode != 0:

        msg = "Failed to generate fix rules with the oscap tool: %s" % proc.stderr

        raise OSCAPaddonError(msg)

    return proc.stdout

def run_oscap_remediate(profile, fpath, ds_id="", xccdf_id="", tailoring="",

                        chroot=""):

    """

    Run the evaluation and remediation with the oscap tool on a given file,

    doing the remediation as defined in a given profile defined in a given

    checklist that is a part of a given datastream. If requested, run in

    chroot.

    :param profile: id of the profile that will drive the remediation

    :type profile: str

    :param fpath: path to a file with SCAP content

    :type fpath: str

    :param ds_id: ID of the datastream that contains the checklist defining

                  the profile

    :type ds_id: str

    :param xccdf_id: ID of the checklist that defines the profile

    :type xccdf_id: str

    :param tailoring: path to a tailoring file

    :type tailoring: str

    :param chroot: path to the root the oscap tool should be run in

    :type chroot: str

    :return: oscap tool's stdout (summary of the rules, checks and fixes)

    :rtype: str

    """

    if not profile:

        return ""

    def do_chroot():

        """Helper function doing the chroot if requested."""

        if chroot and chroot != "/":

            os.chroot(chroot)

            os.chdir("/")

    # make sure the directory for the results exists

    results_dir = os.path.dirname(RESULTS_PATH)

    if chroot:

        results_dir = os.path.normpath(chroot + "/" + results_dir)

    utils.ensure_dir_exists(results_dir)

    args = ["oscap", "xccdf", "eval"]

    args.append("--remediate")

    args.append("--results=%s" % RESULTS_PATH)

    args.append("--report=%s" % REPORT_PATH)

    # oscap uses the default profile by default

    if profile.lower() != "default":

        args.append("--profile=%s" % profile)

    if ds_id:

        args.append("--datastream-id=%s" % ds_id)

    if xccdf_id:

        args.append("--xccdf-id=%s" % xccdf_id)

    if tailoring:

        args.append("--tailoring-file=%s" % tailoring)

    args.append(fpath)

    proc = SubprocessLauncher(args)

    proc.execute(preexec_fn=do_chroot)

    proc.log_messages()

    if proc.returncode not in (0, 2):

        # 0 -- success; 2 -- no error, but checks/remediation failed

        msg = "Content evaluation and remediation with the oscap tool "\

            "failed: %s" % proc.stderr

        raise OSCAPaddonError(msg)

    return proc.stdout

def wait_and_fetch_net_data(url, out_file, ca_certs=None):

    """

    Function that waits for network connection and starts a thread that fetches

    data over network.

    :see: org_fedora_oscap.data_fetch.fetch_data

    :return: the name of the thread running fetch_data

    :rtype: str

    """

    # get thread that tries to establish a network connection

    nm_conn_thread = threadMgr.get(constants.THREAD_WAIT_FOR_CONNECTING_NM)

    if nm_conn_thread:

        # NM still connecting, wait for it to finish

        nm_conn_thread.join()

    network_proxy = NETWORK.get_proxy()

    if not network_proxy.Connected:

        raise OSCAPaddonNetworkError("Network connection needed to fetch data.")

    fetch_data_thread = AnacondaThread(name=THREAD_FETCH_DATA,

                                       target=fetch_data,

                                       args=(url, out_file, ca_certs),

                                       fatal=False)

    # register and run the thread

    threadMgr.add(fetch_data_thread)

    return THREAD_FETCH_DATA

def extract_data(archive, out_dir, ensure_has_files=None):

    """

    Fuction that extracts the given archive to the given output directory. It

    tries to find out the archive type by the file name.

    :param archive: path to the archive file that should be extracted

    :type archive: str

    :param out_dir: output directory the archive should be extracted to

    :type out_dir: str

    :param ensure_has_files: relative paths to the files that must exist in the

                             archive

    :type ensure_has_files: iterable of strings or None

    :return: a list of files and directories extracted from the archive

    :rtype: [str]

    """

    # get rid of empty file paths

    ensure_has_files = [fpath for fpath in ensure_has_files if fpath]

    if archive.endswith(".zip"):

        # ZIP file

        try:

            zfile = zipfile.ZipFile(archive, "r")

        except zipfile.BadZipfile as err:

            raise ExtractionError(str(err))

        # generator for the paths of the files found in the archive (dirs end

        # with "/")

        files = set(info.filename for info in zfile.filelist

                    if not info.filename.endswith("/"))

        for fpath in ensure_has_files or ():

            if fpath not in files:

                msg = "File '%s' not found in the archive '%s'" % (fpath,

                                                                   archive)

                raise ExtractionError(msg)

        utils.ensure_dir_exists(out_dir)

        zfile.extractall(path=out_dir)

        result = [utils.join_paths(out_dir, info.filename) for info in zfile.filelist]

        zfile.close()

        return result

    elif archive.endswith(".tar"):

        # plain tarball

        return _extract_tarball(archive, out_dir, ensure_has_files, None)

    elif archive.endswith(".tar.gz"):

        # gzipped tarball

        return _extract_tarball(archive, out_dir, ensure_has_files, "gz")

    elif archive.endswith(".tar.bz2"):

        # bzipped tarball

        return _extract_tarball(archive, out_dir, ensure_has_files, "bz2")

    elif archive.endswith(".rpm"):

        # RPM

        return _extract_rpm(archive, out_dir, ensure_has_files)

    # elif other types of archives

    else:

        raise ExtractionError("Unsuported archive type")

def _extract_tarball(archive, out_dir, ensure_has_files, alg):

    """

    Extract the given TAR archive to the given output directory and make sure

    the given file exists in the archive.

    :see: extract_data

    :param alg: compression algorithm used for the tarball

    :type alg: str (one of "gz", "bz2") or None

    :return: a list of files and directories extracted from the archive

    :rtype: [str]

    """

    if alg and alg not in ("gz", "bz2",):

        raise ExtractionError("Unsupported compression algorithm")

    mode = "r"

    if alg:

        mode += ":%s" % alg

    try:

        tfile = tarfile.TarFile.open(archive, mode)

    except tarfile.TarError as err:

        raise ExtractionError(str(err))

    # generator for the paths of the files found in the archive

    files = set(member.path for member in tfile.getmembers()

                if member.isfile())

    for fpath in ensure_has_files or ():

        if fpath not in files:

            msg = "File '%s' not found in the archive '%s'" % (fpath, archive)

            raise ExtractionError(msg)

    utils.ensure_dir_exists(out_dir)

    tfile.extractall(path=out_dir)

    result = [utils.join_paths(out_dir, member.path) for member in tfile.getmembers()]

    tfile.close()

    return result

def _extract_rpm(rpm_path, root="/", ensure_has_files=None):

    """

    Extract the given RPM into the directory tree given by the root argument

    and make sure the given file exists in the archive.

    :param rpm_path: path to the RPM file that should be extracted

    :type rpm_path: str

    :param root: root of the directory tree the RPM should be extracted into

    :type root: str

    :param ensure_has_files: relative paths to the files that must exist in the

                             RPM

    :type ensure_has_files: iterable of strings or None

    :return: a list of files and directories extracted from the archive

    :rtype: [str]

    """

    # run rpm2cpio and process the output with the cpioarchive module

    temp_fd, temp_path = tempfile.mkstemp(prefix="oscap_rpm")

    proc = subprocess.Popen(["rpm2cpio", rpm_path], stdout=temp_fd)

    proc.wait()

    if proc.returncode != 0:

        msg = "Failed to convert RPM '%s' to cpio archive" % rpm_path

        raise ExtractionError(msg)

    os.close(temp_fd)

    try:

        archive = cpioarchive.CpioArchive(temp_path)

    except cpioarchive.CpioError as err:

        raise ExtractionError(str(err))

    # get entries from the archive (supports only iteration over entries)

    entries = set(entry for entry in archive)

    # cpio entry names (paths) start with the dot

    entry_names = [entry.name.lstrip(".") for entry in entries]

    for fpath in ensure_has_files or ():

        # RPM->cpio entries have absolute paths

        if fpath not in entry_names and \

           os.path.join("/", fpath) not in entry_names:

            msg = "File '%s' not found in the archive '%s'" % (fpath, rpm_path)

            raise ExtractionError(msg)

    try:

        for entry in entries:

            if entry.size == 0:

                continue

            dirname = os.path.dirname(entry.name.lstrip("."))

            out_dir = os.path.normpath(root + dirname)

            utils.ensure_dir_exists(out_dir)

            out_fpath = os.path.normpath(root + entry.name.lstrip("."))

            if os.path.exists(out_fpath):

                continue

            with open(out_fpath, "wb") as out_file:

                buf = entry.read(IO_BUF_SIZE)

                while buf:

                    out_file.write(buf)

                    buf = entry.read(IO_BUF_SIZE)

    except (IOError, cpioarchive.CpioError) as e:

        raise ExtractionError(e)

    # cleanup

    archive.close()

    os.unlink(temp_path)

    return [os.path.normpath(root + name) for name in entry_names]

def strip_content_dir(fpaths, phase="preinst"):

    """

    Strip content directory prefix from the file paths for either

    pre-installation or post-installation phase.

    :param fpaths: iterable of file paths to strip content directory prefix

                   from

    :type fpaths: iterable of strings

    :param phase: specifies pre-installation or post-installation phase

    :type phase: "preinst" or "postinst"

    :return: the same iterable of file paths as given with the content

             directory prefix stripped

    :rtype: same type as fpaths

    """

    if phase == "preinst":

        remove_prefix = lambda x: x[len(INSTALLATION_CONTENT_DIR):]

    else:

        remove_prefix = lambda x: x[len(TARGET_CONTENT_DIR):]

    return utils.keep_type_map(remove_prefix, fpaths)

def ssg_available(root="/"):

    """

    Tries to find the SCAP Security Guide under the given root.

    :return: True if SSG was found under the given root, False otherwise

    """

    return os.path.exists(utils.join_paths(root, SSG_DIR + SSG_CONTENT))

def dry_run_skip(func):

    """

    Decorator that makes sure the decorated function is noop in the dry-run

    mode.

    :param func: a decorated function that needs to have the first parameter an

                 object with the _addon_data attribute referencing the OSCAP

                 addon's ksdata

    """

    @wraps(func)

    def decorated(self, *args, **kwargs):

        if self._addon_data.dry_run:

            return

        else:

            return func(self, *args, **kwargs)

    return decorated