#!/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
    from ipaserver.install import installutils
    from ipapython.dn import DN
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.x509 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(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)',
            ['userCertificate'],
            DN(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():
    installutils.check_server_configuration()

    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

try:
    if not os.geteuid()==0:
        sys.exit("\nMust be root to check compliance\n")

    main()
except SystemExit, e:
    sys.exit(e)
except RuntimeError, e:
    sys.exit(e)