#!/usr/bin/env python
#
# Authors:
#   Rob Crittenden <rcritten@redhat.com>
#
# Copyright (C) 2010  Red Hat
# see file 'COPYING' for use and warranty information
#
# 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/>.
#
# An LDAP client to count entitlements and log to syslog if the number is
# exceeded.

try:
    import sys
    import os
    import syslog
    import tempfile
    import krbV
    import base64
    import shutil

    from rhsm.certificate import EntitlementCertificate

    from ipaserver.plugins.ldap2 import ldap2
    from ipalib import api, errors, backend
except ImportError, e:
    # If python-rhsm isn't installed exit gracefully and quietly.
    if e.args[0] == 'No module named rhsm.certificate':
        sys.exit(0)
    print >> sys.stderr, """\
There was a problem importing one of the required Python modules. The
error was:

    %s
""" % sys.exc_value
    sys.exit(1)

# Each IPA server comes with this many entitlements
DEFAULT_ENTITLEMENTS = 25

class client(backend.Executioner):
    """
    A simple-minded IPA client that can execute remote commands.
    """

    def run(self, method, **kw):
        self.create_context()
        result = self.execute(method, **kw)
        return result

def parse_options():
    from optparse import OptionParser

    parser = OptionParser()
    parser.add_option("--debug", dest="debug", action="store_true",
        default=False, help="enable debugging")

    options, args = parser.parse_args()
    return options, args

def check_compliance(tmpdir, debug=False):
    cfg = dict(
        context='cli',
        in_server=False,
        debug=debug,
        verbose=0,
    )

    api.bootstrap(**cfg)
    api.register(client)
    api.finalize()
    from ipalib.plugins.service import normalize_certificate, make_pem

    try:
        # Create a new credentials cache for this tool. This executes
        # using the systems host principal.
        ccache_file = 'FILE:%s/ccache' % tmpdir
        krbcontext = krbV.default_context()
        principal = str('host/%s@%s' % (api.env.host, api.env.realm))
        keytab = krbV.Keytab(name='/etc/krb5.keytab', context=krbcontext)
        principal = krbV.Principal(name=principal, context=krbcontext)
        os.environ['KRB5CCNAME'] = ccache_file
        ccache = krbV.CCache(name=ccache_file, context=krbcontext, primary_principal=principal)
        ccache.init(principal)
        ccache.init_creds_keytab(keytab=keytab, principal=principal)
    except krbV.Krb5Error, e:
        raise StandardError('Error initializing principal %s in %s: %s' % (principal.name, '/etc/krb5.keytab', str(e)))

    # entitle-sync doesn't return any information we want to see, it just
    # needs to be done so the LDAP data is correct.
    try:
        result = api.Backend.client.run('entitle_sync')
    except errors.NotRegisteredError:
        # Even if not registered they have some default entitlements
        pass

    conn = ldap2(shared_instance=False)

    # Bind using GSSAPI
    conn.connect(ccache=ccache_file)

    hostcount = 0
    # Get the hosts first
    try:
        (entries, truncated) = conn.find_entries('(krblastpwdchange=*)', ['dn'],
            '%s,%s' % (api.env.container_host, api.env.basedn),
            conn.SCOPE_ONELEVEL,
            size_limit = -1)
    except errors.NotFound:
         # No hosts
         pass

    if not truncated:
        hostcount = len(entries)
    else:
        # This will not happen unless we bump into a server-side limit.
        msg = 'The host count result was truncated, they will be underreported'
        syslog.syslog(syslog.LOG_ERR, msg)
        if sys.stdin.isatty():
            print msg

    available = 0
    try:
        (entries, truncated) = conn.find_entries('(objectclass=ipaentitlement)',
        ['dn', 'userCertificate'],
        '%s,%s' % (api.env.container_entitlements, api.env.basedn),
        conn.SCOPE_ONELEVEL,
        size_limit = -1)

        for entry in entries:
            (dn, attrs) = entry
            if 'usercertificate' in attrs:
                rawcert = attrs['usercertificate'][0]
                rawcert = normalize_certificate(rawcert)
                cert = make_pem(base64.b64encode(rawcert))
                cert = EntitlementCertificate(cert)
                order = cert.getOrder()
                available += int(order.getQuantityUsed())
    except errors.NotFound:
        pass

    conn.disconnect()

    available += DEFAULT_ENTITLEMENTS

    if hostcount > available:
        syslog.syslog(syslog.LOG_ERR, 'IPA is out of compliance: %d of %d entitlements used.' % (hostcount, available))
        if sys.stdin.isatty():
            print 'IPA is out of compliance: %d of %d entitlements used.' % (hostcount, available)
    else:
        if sys.stdin.isatty():
            # If run from the command-line display some info
            print 'IPA is in compliance: %d of %d entitlements used.' % (hostcount, available)

def main():
    if os.getegid() != 0:
        sys.exit("Must be root to check compliance")

    if not os.path.exists('/etc/ipa/default.conf'):
        return 0

    options, args = parse_options()

    try:
        tmpdir = tempfile.mkdtemp(prefix = "tmp-")
        try:
            check_compliance(tmpdir, options.debug)
        finally:
            shutil.rmtree(tmpdir)
    except KeyboardInterrupt:
        return 1
    except (StandardError, errors.PublicError), e:
        syslog.syslog(syslog.LOG_ERR, 'IPA compliance checking failed: %s' % str(e))
        if sys.stdin.isatty():
            print 'IPA compliance checking failed: %s' % str(e)
        return 1

    return 0

sys.exit(main())