# -*- 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 choice, shuffle

from subprocess import Popen, PIPE

try:

    import hashlib

except ImportError:

    from VirtualMailManager.pycompat import hashlib

from VirtualMailManager import ENCODING, Configuration

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

_get_salt = lambda s_len: ''.join(choice(SALTCHARS) for x in xrange(s_len))

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 = [Configuration.dget('bin.dovecotpw'), '-s', scheme, '-p',

                get_unicode(password)]

    if Configuration.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)

    return stdout.strip()

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 _crypt_hash(password, scheme, encoding):

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

    if scheme == 'CRYPT':

        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').rstrip()

    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 Configuration.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.

    """

    assert Configuration is not None

    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 = Configuration.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 Configuration.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 Configuration.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)

def randompw():

    """Generates a plain text random password.

    The length of the password can be configured in the ``vmm.cfg``

    (account.password_length).

    """

    assert Configuration is not None

    pw_chars = list(PASSWDCHARS)

    shuffle(pw_chars)

    pw_len = Configuration.dget('account.password_length')

    if pw_len < 8:

        pw_len = 8

    return ''.join(choice(pw_chars) for x in xrange(pw_len))

del _