# vim: tabstop=4 shiftwidth=4 softtabstop=4

# Copyright 2010 United States Government as represented by the
# Administrator of the National Aeronautics and Space Administration.
# All Rights Reserved.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.
"""
Wrappers around standard crypto data elements.

Includes root and intermediate CAs, SSH key_pairs and x509 certificates.
"""

import base64
import hashlib
import logging
import os
import shutil
import struct
import tempfile
import time
import utils

import M2Crypto

from nova import context
from nova import db
from nova import flags


FLAGS = flags.FLAGS
flags.DEFINE_string('ca_file', 'cacert.pem', 'Filename of root CA')
flags.DEFINE_string('key_file',
                    os.path.join('private', 'cakey.pem'),
                    'Filename of private key')
flags.DEFINE_string('crl_file', 'crl.pem',
                    'Filename of root Certificate Revokation List')
flags.DEFINE_string('keys_path', '$state_path/keys',
                    'Where we keep our keys')
flags.DEFINE_string('ca_path', '$state_path/CA',
                    'Where we keep our root CA')
flags.DEFINE_boolean('use_project_ca', False,
                     'Should we use a CA for each project?')
flags.DEFINE_string('user_cert_subject',
                    '/C=US/ST=California/L=MountainView/O=AnsoLabs/'
                    'OU=NovaDev/CN=%s-%s-%s',
                    'Subject for certificate for users, '
                    '%s for project, user, timestamp')
flags.DEFINE_string('project_cert_subject',
                    '/C=US/ST=California/L=MountainView/O=AnsoLabs/'
                    'OU=NovaDev/CN=project-ca-%s-%s',
                    'Subject for certificate for projects, '
                    '%s for project, timestamp')
flags.DEFINE_string('vpn_cert_subject',
                    '/C=US/ST=California/L=MountainView/O=AnsoLabs/'
                    'OU=NovaDev/CN=project-vpn-%s-%s',
                    'Subject for certificate for vpns, '
                    '%s for project, timestamp')


def ca_folder(project_id=None):
    if FLAGS.use_project_ca and project_id:
        return os.path.join(FLAGS.ca_path, 'projects', project_id)
    return FLAGS.ca_path


def ca_path(project_id=None):
    return os.path.join(ca_folder(project_id), FLAGS.ca_file)


def key_path(project_id=None):
    return os.path.join(ca_folder(project_id), FLAGS.key_file)


def fetch_ca(project_id=None, chain=True):
    if not FLAGS.use_project_ca:
        project_id = None
    buffer = ""
    if project_id:
        with open(ca_path(project_id), "r") as cafile:
            buffer += cafile.read()
        if not chain:
            return buffer
    with open(ca_path(None), "r") as cafile:
        buffer += cafile.read()
    return buffer


def generate_key_pair(bits=1024):
    # what is the magic 65537?

    tmpdir = tempfile.mkdtemp()
    keyfile = os.path.join(tmpdir, 'temp')
    utils.execute('ssh-keygen -q -b %d -N "" -f %s' % (bits, keyfile))
    (out, err) = utils.execute('ssh-keygen -q -l -f %s.pub' % (keyfile))
    fingerprint = out.split(' ')[1]
    private_key = open(keyfile).read()
    public_key = open(keyfile + '.pub').read()

    shutil.rmtree(tmpdir)
    # code below returns public key in pem format
    # key = M2Crypto.RSA.gen_key(bits, 65537, callback=lambda: None)
    # private_key = key.as_pem(cipher=None)
    # bio = M2Crypto.BIO.MemoryBuffer()
    # key.save_pub_key_bio(bio)
    # public_key = bio.read()
    # public_key, err = execute('ssh-keygen -y -f /dev/stdin', private_key)

    return (private_key, public_key, fingerprint)


def ssl_pub_to_ssh_pub(ssl_public_key, name='root', suffix='nova'):
    buf = M2Crypto.BIO.MemoryBuffer(ssl_public_key)
    rsa_key = M2Crypto.RSA.load_pub_key_bio(buf)
    e, n = rsa_key.pub()

    key_type = 'ssh-rsa'

    key_data = struct.pack('>I', len(key_type))
    key_data += key_type
    key_data += '%s%s' % (e, n)

    b64_blob = base64.b64encode(key_data)
    return '%s %s %s@%s\n' % (key_type, b64_blob, name, suffix)


def revoke_cert(project_id, file_name):
    """Revoke a cert by file name"""
    start = os.getcwd()
    os.chdir(ca_folder(project_id))
    # NOTE(vish): potential race condition here
    utils.execute("openssl ca -config ./openssl.cnf -revoke '%s'" % file_name)
    utils.execute("openssl ca -gencrl -config ./openssl.cnf -out '%s'" %
                  FLAGS.crl_file)
    os.chdir(start)


def revoke_certs_by_user(user_id):
    """Revoke all user certs"""
    admin = context.get_admin_context()
    for cert in db.certificate_get_all_by_user(admin, user_id):
        revoke_cert(cert['project_id'], cert['file_name'])


def revoke_certs_by_project(project_id):
    """Revoke all project certs"""
    # NOTE(vish): This is somewhat useless because we can just shut down
    #             the vpn.
    admin = context.get_admin_context()
    for cert in db.certificate_get_all_by_project(admin, project_id):
        revoke_cert(cert['project_id'], cert['file_name'])


def revoke_certs_by_user_and_project(user_id, project_id):
    """Revoke certs for user in project"""
    admin = context.get_admin_context()
    for cert in db.certificate_get_all_by_user(admin, user_id, project_id):
        revoke_cert(cert['project_id'], cert['file_name'])


def _project_cert_subject(project_id):
    """Helper to generate user cert subject"""
    return FLAGS.project_cert_subject % (project_id, utils.isotime())


def _vpn_cert_subject(project_id):
    """Helper to generate user cert subject"""
    return FLAGS.vpn_cert_subject % (project_id, utils.isotime())


def _user_cert_subject(user_id, project_id):
    """Helper to generate user cert subject"""
    return FLAGS.user_cert_subject % (project_id, user_id, utils.isotime())


def generate_x509_cert(user_id, project_id, bits=1024):
    """Generate and sign a cert for user in project"""
    subject = _user_cert_subject(user_id, project_id)
    tmpdir = tempfile.mkdtemp()
    keyfile = os.path.abspath(os.path.join(tmpdir, 'temp.key'))
    csrfile = os.path.join(tmpdir, 'temp.csr')
    utils.execute("openssl genrsa -out %s %s" % (keyfile, bits))
    utils.execute("openssl req -new -key %s -out %s -batch -subj %s" %
                  (keyfile, csrfile, subject))
    private_key = open(keyfile).read()
    csr = open(csrfile).read()
    shutil.rmtree(tmpdir)
    (serial, signed_csr) = sign_csr(csr, project_id)
    fname = os.path.join(ca_folder(project_id), "newcerts/%s.pem" % serial)
    cert = {'user_id': user_id,
            'project_id': project_id,
            'file_name': fname}
    db.certificate_create(context.get_admin_context(), cert)
    return (private_key, signed_csr)


def _ensure_project_folder(project_id):
    if not os.path.exists(ca_path(project_id)):
        start = os.getcwd()
        os.chdir(ca_folder())
        utils.execute("sh geninter.sh %s %s" %
                      (project_id, _project_cert_subject(project_id)))
        os.chdir(start)


def generate_vpn_files(project_id):
    project_folder = ca_folder(project_id)
    csr_fn = os.path.join(project_folder, "server.csr")
    crt_fn = os.path.join(project_folder, "server.crt")

    if os.path.exists(crt_fn):
        return
    _ensure_project_folder(project_id)
    start = os.getcwd()
    os.chdir(ca_folder())
    # TODO(vish): the shell scripts could all be done in python
    utils.execute("sh genvpn.sh %s %s" %
                  (project_id, _vpn_cert_subject(project_id)))
    with open(csr_fn, "r") as csrfile:
        csr_text = csrfile.read()
    (serial, signed_csr) = sign_csr(csr_text, project_id)
    with open(crt_fn, "w") as crtfile:
        crtfile.write(signed_csr)
    os.chdir(start)


def sign_csr(csr_text, project_id=None):
    if not FLAGS.use_project_ca:
        project_id = None
    if not project_id:
        return _sign_csr(csr_text, ca_folder())
    _ensure_project_folder(project_id)
    project_folder = ca_folder(project_id)
    return _sign_csr(csr_text, ca_folder(project_id))


def _sign_csr(csr_text, ca_folder):
    tmpfolder = tempfile.mkdtemp()
    inbound = os.path.join(tmpfolder, "inbound.csr")
    outbound = os.path.join(tmpfolder, "outbound.csr")
    csrfile = open(inbound, "w")
    csrfile.write(csr_text)
    csrfile.close()
    logging.debug("Flags path: %s", ca_folder)
    start = os.getcwd()
    # Change working dir to CA
    os.chdir(ca_folder)
    utils.execute("openssl ca -batch -out %s -config "
                  "./openssl.cnf -infiles %s" % (outbound, inbound))
    out, _err = utils.execute("openssl x509 -in %s -serial -noout" % outbound)
    serial = out.rpartition("=")[2]
    os.chdir(start)
    with open(outbound, "r") as crtfile:
        return (serial, crtfile.read())


def mkreq(bits, subject="foo", ca=0):
    pk = M2Crypto.EVP.PKey()
    req = M2Crypto.X509.Request()
    rsa = M2Crypto.RSA.gen_key(bits, 65537, callback=lambda: None)
    pk.assign_rsa(rsa)
    rsa = None  # should not be freed here
    req.set_pubkey(pk)
    req.set_subject(subject)
    req.sign(pk, 'sha512')
    assert req.verify(pk)
    pk2 = req.get_pubkey()
    assert req.verify(pk2)
    return req, pk


def mkcacert(subject='nova', years=1):
    req, pk = mkreq(2048, subject, ca=1)
    pkey = req.get_pubkey()
    sub = req.get_subject()
    cert = M2Crypto.X509.X509()
    cert.set_serial_number(1)
    cert.set_version(2)
    # FIXME subject is not set in mkreq yet
    cert.set_subject(sub)
    t = long(time.time()) + time.timezone
    now = M2Crypto.ASN1.ASN1_UTCTIME()
    now.set_time(t)
    nowPlusYear = M2Crypto.ASN1.ASN1_UTCTIME()
    nowPlusYear.set_time(t + (years * 60 * 60 * 24 * 365))
    cert.set_not_before(now)
    cert.set_not_after(nowPlusYear)
    issuer = M2Crypto.X509.X509_Name()
    issuer.C = "US"
    issuer.CN = subject
    cert.set_issuer(issuer)
    cert.set_pubkey(pkey)
    ext = M2Crypto.X509.new_extension('basicConstraints', 'CA:TRUE')
    cert.add_ext(ext)
    cert.sign(pk, 'sha512')

    # print 'cert', dir(cert)
    print cert.as_pem()
    print pk.get_rsa().as_pem()

    return cert, pk, pkey


# Copyright (c) 2006-2009 Mitch Garnaat http://garnaat.org/
#
# Permission is hereby granted, free of charge, to any person obtaining a
# copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish, dis-
# tribute, sublicense, and/or sell copies of the Software, and to permit
# persons to whom the Software is furnished to do so, subject to the fol-
# lowing conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABIL-
# ITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
# SHALL THE AUTHOR BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
# IN THE SOFTWARE.
# http://code.google.com/p/boto

def compute_md5(fp):
    """
    :type fp: file
    :param fp: File pointer to the file to MD5 hash.  The file pointer will be
               reset to the beginning of the file before the method returns.

    :rtype: tuple
    :return: the hex digest version of the MD5 hash
    """
    m = hashlib.md5()
    fp.seek(0)
    s = fp.read(8192)
    while s:
        m.update(s)
        s = fp.read(8192)
    hex_md5 = m.hexdigest()
    # size = fp.tell()
    fp.seek(0)
    return hex_md5