#!/usr/bin/python3
#
# The Qubes OS Project, http://www.qubes-os.org
#
# Copyright (C) 2010  Rafal Wojtczuk  <rafal@invisiblethingslab.com>
#
# 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
#
import os
import os.path
import re
import sys
import subprocess
import shutil
import grp
import qubesadmin

updates_dir = "/var/lib/qubes/updates"
updates_rpm_dir = updates_dir + "/rpm"
updates_repodata_dir = updates_dir + "/repodata"
updates_error_file = updates_dir + "/errors"

comps_file = None
if os.path.exists('/usr/share/qubes/Qubes-comps.xml'):
    comps_file = '/usr/share/qubes/Qubes-comps.xml'

package_regex = re.compile(r"^[A-Za-z0-9._+-]{1,128}\.rpm$")
# example valid outputs:
#  .....rpm: rsa sha1 (md5) pgp md5 OK
#  .....rpm: (sha1) dsa sha1 md5 gpg OK
#  .....rpm: digests signatures OK
# example INVALID outputs:
#  .....rpm: sha1 md5 OK
#  .....rpm: RSA sha1 ((MD5) PGP) md5 NOT OK (MISSING KEYS: (MD5) PGP#246110c1)
#  .....rpm: digests OK
gpg_ok_regex = re.compile(r": [a-z0-9() ]* (pgp|gpg|signatures) [a-z0-9 ]*OK$")


def dom0updates_fatal(msg):
    print(msg, file=sys.stderr)
    with open(updates_error_file, "a") as updates_error_file_handle:
        updates_error_file_handle.write(msg + "\n")
    shutil.rmtree(updates_rpm_dir)
    exit(1)


def handle_dom0updates(updatevm):
    source = os.getenv("QREXEC_REMOTE_DOMAIN")
    if source != updatevm.name:
        print('Domain ' + str(source) + ' not allowed to send dom0 updates',
            file=sys.stderr)
        exit(1)
    # Clean old packages
    if os.path.exists(updates_rpm_dir):
        shutil.rmtree(updates_rpm_dir)
    if os.path.exists(updates_repodata_dir):
        shutil.rmtree(updates_repodata_dir)
    if os.path.exists(updates_error_file):
        os.remove(updates_error_file)
    os.environ['LC_ALL'] = 'C'
    qubes_gid = grp.getgrnam('qubes').gr_gid
    old_umask = os.umask(0o002)
    os.mkdir(updates_rpm_dir)
    os.chown(updates_rpm_dir, -1, qubes_gid)
    os.chmod(updates_rpm_dir, 0o0775)
    try:
        subprocess.check_call(["/usr/libexec/qubes/qfile-dom0-unpacker",
            str(os.getuid()), updates_rpm_dir])
        # Verify received files
        for untrusted_f in os.listdir(updates_rpm_dir):
            if not package_regex.match(untrusted_f):
                raise Exception(
                    'Domain ' + source + ' sent unexpected file')
            f = untrusted_f
            assert '/' not in f
            assert '\0' not in f
            assert '\x1b' not in f

            full_path = updates_rpm_dir + "/" + f
            if os.path.islink(full_path) or not os.path.isfile(full_path):
                raise Exception(
                    'Domain ' + source + ' sent not regular file')
            p = subprocess.Popen(["/bin/rpm", "-K", full_path],
                    stdout=subprocess.PIPE)
            output = p.communicate()[0].decode('ascii')
            if p.returncode != 0:
                raise Exception(
                    'Error while verifing %s signature: %s' % (f, output))
            if not gpg_ok_regex.search(output.strip()):
                raise Exception(
                    'Domain ' + source + ' sent not signed rpm: ' + f)
    except Exception as e:
        dom0updates_fatal(str(e))
    # After updates received - create repo metadata
    createrepo_cmd = ["/usr/bin/createrepo_c"]
    if comps_file:
        createrepo_cmd += ["-g", comps_file]
    createrepo_cmd += ["-q", updates_dir]
    subprocess.check_call(createrepo_cmd)
    os.chown(updates_repodata_dir, -1, qubes_gid)
    os.chmod(updates_repodata_dir, 0o0775)
    # Clean old cache
    subprocess.call(["sudo", "/usr/bin/yum", "-q", "clean", "all"],
        stdout=sys.stderr)
    os.umask(old_umask)
    exit(0)


def main():
    app = qubesadmin.Qubes()
    
    updatevm = app.updatevm
    if updatevm is None:
        exit(1)
    handle_dom0updates(updatevm)


if __name__ == '__main__':
    main()