# -*- coding: UTF-8 -*-

# Copyright (c) 2010, Pascal Volk

# See COPYING for distribution information.

"""

    VirtualMailManager.password

    VirtualMailManager's password module to generate password hashes from

    passwords or random passwords. There are two functions:

        hashed_password = pwhash(password[, scheme][, user])

        random_password = randompw()

"""

from crypt import crypt

from random import SystemRandom

from subprocess import Popen, PIPE

try:

    import hashlib

except ImportError:

    from VirtualMailManager.pycompat import hashlib

from VirtualMailManager import ENCODING

from VirtualMailManager.EmailAddress import EmailAddress

from VirtualMailManager.common import get_unicode, version_str

from VirtualMailManager.constants.ERROR import VMM_ERROR

from VirtualMailManager.errors import VMMError

COMPAT = hasattr(hashlib, 'compat')

SALTCHARS = './0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'

PASSWDCHARS = '._-+#*23456789abcdefghikmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ'

DEFAULT_B64 = (None, 'B64', 'BASE64')

DEFAULT_HEX = (None, 'HEX')

_ = lambda msg: msg

cfg_dget = lambda option: None

_sys_rand = SystemRandom()

_get_salt = lambda salt_len: ''.join(_sys_rand.sample(SALTCHARS, salt_len))

def _test_crypt_algorithms():

    """Check for Blowfish/SHA-256/SHA-512 support in crypt.crypt()."""

    blowfish_ = sha256_ = sha512_ = False

    _blowfish = '$2a$04$0123456789abcdefABCDE.N.drYX5yIAL1LkTaaZotW3yI0hQhZru'

    _sha256 = '$5$rounds=1000$0123456789abcdef$K/DksR0DT01hGc8g/kt9McEgrbFMKi\

9qrb1jehe7hn4'

    _sha512 = '$6$rounds=1000$0123456789abcdef$ZIAd5WqfyLkpvsVCVUU1GrvqaZTqvh\

JoouxdSqJO71l9Ld3tVrfOatEjarhghvEYADkq//LpDnTeO90tcbtHR1'

    if crypt('08/15!test~4711', '$2a$04$0123456789abcdefABCDEF$') == _blowfish:

        blowfish_ = True

    if crypt('08/15!test~4711', '$5$rounds=1000$0123456789abcdef$') == _sha256:

        sha256_ = True

    if crypt('08/15!test~4711', '$6$rounds=1000$0123456789abcdef$') == _sha512:

        sha512_ = True

    return blowfish_, sha256_, sha512_

CRYPT_BLOWFISH, CRYPT_SHA256, CRYPT_SHA512 = _test_crypt_algorithms()

def _dovecotpw(password, scheme, encoding):

    """Communicates with dovecotpw (Dovecot 2.0: `doveadm pw`) and returns

    the hashed password: {scheme[.encoding]}hash

    """

    if encoding:

        scheme = '.'.join((scheme, encoding))

    cmd_args = [cfg_dget('bin.dovecotpw'), '-s', scheme, '-p',

                get_unicode(password)]

    if cfg_dget('misc.dovecot_version') >= 0x20000a01:

        cmd_args.insert(1, 'pw')

    process = Popen(cmd_args, stdout=PIPE, stderr=PIPE)

    stdout, stderr = process.communicate()

    if process.returncode:

        raise VMMError(stderr.strip(), VMM_ERROR)

    hashed = stdout.strip()

    if not hashed.startswith('{%s}' % scheme):

        raise VMMError('Unexpected result from %s: %s' %

                       (cfg_dget('bin.dovecotpw'), hashed), VMM_ERROR)

    return hashed

def _md4_new():

    """Returns an new MD4-hash object if supported by the hashlib or

    provided by PyCrypto - other `None`.

    """

    try:

        return hashlib.new('md4')

    except ValueError, err:

        if str(err) == 'unsupported hash type':

            if not COMPAT:

                try:

                    from Crypto.Hash import MD4

                    return MD4.new()

                except ImportError:

                    return None

        else:

            raise

def _sha256_new(data=''):

    """Returns a new sha256 object from the hashlib.

    Returns `None` if the PyCrypto in pycompat.hashlib is too old."""

    if not COMPAT:

        return hashlib.sha256(data)

    try:

        return hashlib.new('sha256', data)

    except ValueError, err:

        if str(err) == 'unsupported hash type':

            return None

        else:

            raise

def _format_digest(digest, scheme, encoding):

    """Formats the arguments to a string: {scheme[.encoding]}digest."""

    if not encoding:

        return '{%s}%s' % (scheme, digest)

    return '{%s.%s}%s' % (scheme, encoding, digest)

def _clear_hash(password, scheme, encoding):

    """Generates a (encoded) CLEARTEXT/PLAIN 'hash'."""

    if encoding:

        if encoding == 'HEX':

            password = password.encode('hex')

        else:

            password = password.encode('base64').replace('\n', '')

        return _format_digest(password, scheme, encoding)

    return get_unicode('{%s}%s' % (scheme, password))

def _get_crypt_blowfish_salt():

    """Generates a salt for Blowfish crypt."""

    rounds = cfg_dget('misc.crypt_blowfish_rounds')

    if rounds < 4:

        rounds = 4

    elif rounds > 31:

        rounds = 31

    return '$2a$%02d$%s$' % (rounds, _get_salt(22))

def _get_crypt_shaxxx_salt(crypt_id):

    """Generates a salt for crypt using the SHA-256 or SHA-512 encryption

    method.

    *crypt_id* must be either `5` (SHA-256) or `6` (SHA1-512).

    """

    assert crypt_id in (5, 6), 'invalid crypt id: %r' % crypt_id

    if crypt_id is 6:

        rounds = cfg_dget('misc.crypt_sha512_rounds')

    else:

        rounds = cfg_dget('misc.crypt_sha256_rounds')

    if rounds < 1000:

        rounds = 1000

    elif rounds > 999999999:

        rounds = 999999999

    return '$%d$rounds=%d$%s$' % (crypt_id, rounds, _get_salt(16))

def _crypt_hash(password, scheme, encoding):

    """Generates (encoded) CRYPT/MD5/MD5-CRYPT hashes."""

    if scheme == 'CRYPT':

        if CRYPT_BLOWFISH and cfg_dget('misc.crypt_blowfish_rounds'):

            salt = _get_crypt_blowfish_salt()

        elif CRYPT_SHA512 and cfg_dget('misc.crypt_sha512_rounds'):

            salt = _get_crypt_shaxxx_salt(6)

        elif CRYPT_SHA256 and cfg_dget('misc.crypt_sha256_rounds'):

            salt = _get_crypt_shaxxx_salt(5)

        else:

            salt = _get_salt(2)

    else:

        salt = '$1$%s$' % _get_salt(8)

    encrypted = crypt(password, salt)

    if encoding:

        if encoding == 'HEX':

            encrypted = encrypted.encode('hex')

        else:

            encrypted = encrypted.encode('base64').replace('\n', '')

    return _format_digest(encrypted, scheme, encoding)

def _md4_hash(password, scheme, encoding):

    """Generates encoded PLAIN-MD4 hashes."""

    md4 = _md4_new()

    if md4:

        md4.update(password)

        if encoding in DEFAULT_HEX:

            digest = md4.hexdigest()

        else:

            digest = md4.digest().encode('base64').rstrip()

        return _format_digest(digest, scheme, encoding)

    return _dovecotpw(password, scheme, encoding)

def _md5_hash(password, scheme, encoding, user=None):

    """Generates DIGEST-MD5 aka PLAIN-MD5 and LDAP-MD5 hashes."""

    md5 = hashlib.md5()

    if scheme == 'DIGEST-MD5':

        #  Prior to Dovecot v1.1.12/v1.2.beta2 there was a problem with a

        #  empty auth_realms setting in dovecot.conf and user@domain.tld

        #  usernames. So we have to generate different hashes for different

        #  versions. See also:

        #       http://dovecot.org/list/dovecot-news/2009-March/000103.html

        #       http://hg.dovecot.org/dovecot-1.1/rev/2b0043ba89ae

        if cfg_dget('misc.dovecot_version') >= 0x1010cf00:

            md5.update('%s:%s:' % (user.localpart, user.domainname))

        else:

            md5.update('%s::' % user)

    md5.update(password)

    if (scheme in ('PLAIN-MD5', 'DIGEST-MD5') and encoding in DEFAULT_HEX) \

      or (scheme == 'LDAP-MD5' and encoding == 'HEX'):

        digest = md5.hexdigest()

    else:

        digest = md5.digest().encode('base64').rstrip()

    return _format_digest(digest, scheme, encoding)

def _ntlm_hash(password, scheme, encoding):

    """Generates NTLM hashes."""

    md4 = _md4_new()

    if md4:

        password = ''.join('%s\x00' % c for c in password)

        md4.update(password)

        if encoding in DEFAULT_HEX:

            digest = md4.hexdigest()

        else:

            digest = md4.digest().encode('base64').rstrip()

        return _format_digest(digest, scheme, encoding)

    return _dovecotpw(password, scheme, encoding)

def _sha1_hash(password, scheme, encoding):

    """Generates SHA1 aka SHA hashes."""

    sha1 = hashlib.sha1(password)

    if encoding in DEFAULT_B64:

        digest = sha1.digest().encode('base64').rstrip()

    else:

        digest = sha1.hexdigest()

    return _format_digest(digest, scheme, encoding)

def _sha256_hash(password, scheme, encoding):

    """Generates SHA256 hashes."""

    sha256 = _sha256_new(password)

    if sha256:

        if encoding in DEFAULT_B64:

            digest = sha256.digest().encode('base64').rstrip()

        else:

            digest = sha256.hexdigest()

        return _format_digest(digest, scheme, encoding)

    return _dovecotpw(password, scheme, encoding)

def _sha512_hash(password, scheme, encoding):

    """Generates SHA512 hashes."""

    if not COMPAT:

        sha512 = hashlib.sha512(password)

        if encoding in DEFAULT_B64:

            digest = sha512.digest().encode('base64').replace('\n', '')

        else:

            digest = sha512.hexdigest()

        return _format_digest(digest, scheme, encoding)

    return _dovecotpw(password, scheme, encoding)

def _smd5_hash(password, scheme, encoding):

    """Generates SMD5 (salted PLAIN-MD5) hashes."""

    md5 = hashlib.md5(password)

    salt = _get_salt(4)

    md5.update(salt)

    if encoding in DEFAULT_B64:

        digest = (md5.digest() + salt).encode('base64').rstrip()

    else:

        digest = md5.hexdigest() + salt.encode('hex')

    return _format_digest(digest, scheme, encoding)

def _ssha1_hash(password, scheme, encoding):

    """Generates SSHA (salted SHA/SHA1) hashes."""

    sha1 = hashlib.sha1(password)

    salt = _get_salt(4)

    sha1.update(salt)

    if encoding in DEFAULT_B64:

        digest = (sha1.digest() + salt).encode('base64').rstrip()

    else:

        digest = sha1.hexdigest() + salt.encode('hex')

    return _format_digest(digest, scheme, encoding)

def _ssha256_hash(password, scheme, encoding):

    """Generates SSHA256 (salted SHA256) hashes."""

    sha256 = _sha256_new(password)

    if sha256:

        salt = _get_salt(4)

        sha256.update(salt)

        if encoding in DEFAULT_B64:

            digest = (sha256.digest() + salt).encode('base64').rstrip()

        else:

            digest = sha256.hexdigest() + salt.encode('hex')

        return _format_digest(digest, scheme, encoding)

    return _dovecotpw(password, scheme, encoding)

def _ssha512_hash(password, scheme, encoding):

    """Generates SSHA512 (salted SHA512) hashes."""

    if not COMPAT:

        salt = _get_salt(4)

        sha512 = hashlib.sha512(password + salt)

        if encoding in DEFAULT_B64:

            digest = (sha512.digest() + salt).encode('base64').replace('\n',

                                                                       '')

        else:

            digest = sha512.hexdigest() + salt.encode('hex')

        return _format_digest(digest, scheme, encoding)

    return _dovecotpw(password, scheme, encoding)

_scheme_info = {

    'CLEARTEXT': (_clear_hash, 0x10000f00),

    'CRAM-MD5': (_dovecotpw, 0x10000f00),

    'CRYPT': (_crypt_hash, 0x10000f00),

    'DIGEST-MD5': (_md5_hash, 0x10000f00),

    'HMAC-MD5': (_dovecotpw, 0x10000f00),

    'LANMAN': (_dovecotpw, 0x10000f00),

    'LDAP-MD5': (_md5_hash, 0x10000f00),

    'MD5': (_crypt_hash, 0x10000f00),

    'MD5-CRYPT': (_crypt_hash, 0x10000f00),

    'NTLM': (_ntlm_hash, 0x10000f00),

    'OTP': (_dovecotpw, 0x10100a01),

    'PLAIN': (_clear_hash, 0x10000f00),

    'PLAIN-MD4': (_md4_hash, 0x10000f00),

    'PLAIN-MD5': (_md5_hash, 0x10000f00),

    'RPA': (_dovecotpw, 0x10000f00),

    'SHA': (_sha1_hash, 0x10000f00),

    'SHA1': (_sha1_hash, 0x10000f00),

    'SHA256': (_sha256_hash, 0x10100a01),

    'SHA512': (_sha512_hash, 0x20000b03),

    'SKEY': (_dovecotpw, 0x10100a01),

    'SMD5': (_smd5_hash, 0x10000f00),

    'SSHA': (_ssha1_hash, 0x10000f00),

    'SSHA256': (_ssha256_hash, 0x10200a04),

    'SSHA512': (_ssha512_hash, 0x20000b03),

}

def pwhash(password, scheme=None, user=None):

    """Generates a password hash from the plain text *password* string.

    If no *scheme* is given the password scheme from the configuration will

    be used for the hash generation.  When 'DIGEST-MD5' is used as scheme,

    also an EmailAddress instance must be given as *user* argument.

    """

    if not isinstance(password, basestring):

        raise TypeError('Password is not a string: %r' % password)

    if isinstance(password, unicode):

        password = password.encode(ENCODING)

    password = password.strip()

    if not password:

        raise ValueError("Couldn't accept empty password.")

    if scheme is None:

        scheme = cfg_dget('misc.password_scheme')

    scheme_encoding = scheme.split('.')

    scheme = scheme_encoding[0].upper()

    if not scheme in _scheme_info:

        raise VMMError(_(u"Unsupported password scheme: '%s'") % scheme,

                       VMM_ERROR)

    if cfg_dget('misc.dovecot_version') < _scheme_info[scheme][1]:

        raise VMMError(_(u"The scheme '%s' requires Dovecot >= v%s") %

                       (scheme, version_str(_scheme_info[scheme][1])),

                       VMM_ERROR)

    if len(scheme_encoding) > 1:

        if cfg_dget('misc.dovecot_version') < 0x10100a01:

            raise VMMError(_(u'Encoding suffixes for password schemes require \

Dovecot >= v1.1.alpha1'),

                           VMM_ERROR)

        if scheme_encoding[1].upper() not in ('B64', 'BASE64', 'HEX'):

            raise ValueError('Unsupported encoding: %r' % scheme_encoding[1])

        encoding = scheme_encoding[1].upper()

    else:

        encoding = None

    if scheme == 'DIGEST-MD5':

        assert isinstance(user, EmailAddress)

        return _md5_hash(password, scheme, encoding, user)

    return _scheme_info[scheme][0](password, scheme, encoding)