# 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, including root and intermediate CAs,
SSH keypairs and x509 certificates.
"""

import base64
import hashlib
import logging
import M2Crypto
import os
import shutil
import struct
import tempfile
import time
import utils

from nova import exception
from nova import flags


FLAGS = flags.FLAGS
flags.DEFINE_string('ca_file', 'cacert.pem', 'Filename of root CA')
flags.DEFINE_string('keys_path', utils.abspath('../keys'), 'Where we keep our keys')
flags.DEFINE_string('ca_path', utils.abspath('../CA'), 'Where we keep our root CA')
flags.DEFINE_boolean('use_intermediate_ca', False, 'Should we use intermediate CAs for each project?')

def ca_path(project_id):
    if project_id:
        return "%s/INTER/%s/cacert.pem" % (FLAGS.ca_path, project_id)
    return "%s/cacert.pem" % (FLAGS.ca_path)

def fetch_ca(project_id=None, chain=True):
    if not FLAGS.use_intermediate_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'):
    rsa_key = M2Crypto.RSA.load_pub_key_bio(M2Crypto.BIO.MemoryBuffer(ssl_public_key))
    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 generate_x509_cert(subject, bits=1024):
    tmpdir = tempfile.mkdtemp()
    keyfile = os.path.abspath(os.path.join(tmpdir, 'temp.key'))
    csrfile = os.path.join(tmpdir, 'temp.csr')
    logging.debug("openssl genrsa -out %s %s" % (keyfile, bits))
    utils.runthis("Generating private key: %s", "openssl genrsa -out %s %s" % (keyfile, bits))
    utils.runthis("Generating CSR: %s", "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)
    return (private_key, csr)

def sign_csr(csr_text, intermediate=None):
    if not FLAGS.use_intermediate_ca:
        intermediate = None
    if not intermediate:
        return _sign_csr(csr_text, FLAGS.ca_path)
    user_ca = "%s/INTER/%s" % (FLAGS.ca_path, intermediate)
    if not os.path.exists(user_ca):
        start = os.getcwd()
        os.chdir(FLAGS.ca_path)
        utils.runthis("Generating intermediate CA: %s", "sh geninter.sh %s" % (intermediate))
        os.chdir(start)
    return _sign_csr(csr_text, user_ca)

def _sign_csr(csr_text, ca_folder):
    tmpfolder = tempfile.mkdtemp()
    csrfile = open("%s/inbound.csr" % (tmpfolder), "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.runthis("Signing cert: %s", "openssl ca -batch -out %s/outbound.crt -config ./openssl.cnf -infiles %s/inbound.csr" % (tmpfolder, tmpfolder))
    os.chdir(start)
    with open("%s/outbound.crt" % (tmpfolder), "r") as crtfile:
        return 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)
    cert.set_subject(sub) # FIXME subject is not set in mkreq yet
    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