path: root/src/cryptography/hazmat/backends/openssl/encode_asn1.py

# This file is dual licensed under the terms of the Apache License, Version
# 2.0, and the BSD License. See the LICENSE file in the root of this repository
# for complete details.

from __future__ import absolute_import, division, print_function

import calendar

import idna

import six

from cryptography import x509
from cryptography.hazmat.backends.openssl.decode_asn1 import (
    _CRL_ENTRY_REASON_ENUM_TO_CODE, _DISTPOINT_TYPE_FULLNAME,
    _DISTPOINT_TYPE_RELATIVENAME
)
from cryptography.x509.oid import CRLEntryExtensionOID, ExtensionOID, NameOID


def _encode_asn1_int(backend, x):
    """
    Converts a python integer to an ASN1_INTEGER. The returned ASN1_INTEGER
    will not be garbage collected (to support adding them to structs that take
    ownership of the object). Be sure to register it for GC if it will be
    discarded after use.

    """
    # Convert Python integer to OpenSSL "bignum" in case value exceeds
    # machine's native integer limits (note: `int_to_bn` doesn't automatically
    # GC).
    i = backend._int_to_bn(x)
    i = backend._ffi.gc(i, backend._lib.BN_free)

    # Wrap in an ASN.1 integer.  Don't GC -- as documented.
    i = backend._lib.BN_to_ASN1_INTEGER(i, backend._ffi.NULL)
    backend.openssl_assert(i != backend._ffi.NULL)
    return i


def _encode_asn1_int_gc(backend, x):
    i = _encode_asn1_int(backend, x)
    i = backend._ffi.gc(i, backend._lib.ASN1_INTEGER_free)
    return i


def _encode_asn1_str(backend, data, length):
    """
    Create an ASN1_OCTET_STRING from a Python byte string.
    """
    s = backend._lib.ASN1_OCTET_STRING_new()
    res = backend._lib.ASN1_OCTET_STRING_set(s, data, length)
    backend.openssl_assert(res == 1)
    return s


def _encode_asn1_utf8_str(backend, string):
    """
    Create an ASN1_UTF8STRING from a Python unicode string.
    This object will be an ASN1_STRING with UTF8 type in OpenSSL and
    can be decoded with ASN1_STRING_to_UTF8.
    """
    s = backend._lib.ASN1_UTF8STRING_new()
    res = backend._lib.ASN1_STRING_set(
        s, string.encode("utf8"), len(string.encode("utf8"))
    )
    backend.openssl_assert(res == 1)
    return s


def _encode_asn1_str_gc(backend, data, length):
    s = _encode_asn1_str(backend, data, length)
    s = backend._ffi.gc(s, backend._lib.ASN1_OCTET_STRING_free)
    return s


def _encode_inhibit_any_policy(backend, inhibit_any_policy):
    return _encode_asn1_int_gc(backend, inhibit_any_policy.skip_certs)


def _encode_name(backend, attributes):
    """
    The X509_NAME created will not be gc'd. Use _encode_name_gc if needed.
    """
    subject = backend._lib.X509_NAME_new()
    for attribute in attributes:
        name_entry = _encode_name_entry(backend, attribute)
        res = backend._lib.X509_NAME_add_entry(subject, name_entry, -1, 0)
        backend.openssl_assert(res == 1)
    return subject


def _encode_name_gc(backend, attributes):
    subject = _encode_name(backend, attributes)
    subject = backend._ffi.gc(subject, backend._lib.X509_NAME_free)
    return subject


def _encode_sk_name_entry(backend, attributes):
    """
    The sk_X50_NAME_ENTRY created will not be gc'd.
    """
    stack = backend._lib.sk_X509_NAME_ENTRY_new_null()
    for attribute in attributes:
        name_entry = _encode_name_entry(backend, attribute)
        res = backend._lib.sk_X509_NAME_ENTRY_push(stack, name_entry)
        backend.openssl_assert(res == 1)
    return stack


def _encode_name_entry(backend, attribute):
    value = attribute.value.encode('utf8')
    obj = _txt2obj_gc(backend, attribute.oid.dotted_string)
    if attribute.oid == NameOID.COUNTRY_NAME:
        # Per RFC5280 Appendix A.1 countryName should be encoded as
        # PrintableString, not UTF8String
        type = backend._lib.MBSTRING_ASC
    else:
        type = backend._lib.MBSTRING_UTF8
    name_entry = backend._lib.X509_NAME_ENTRY_create_by_OBJ(
        backend._ffi.NULL, obj, type, value, -1
    )
    return name_entry


def _encode_crl_number(backend, crl_number):
    return _encode_asn1_int_gc(backend, crl_number.crl_number)


def _encode_crl_reason(backend, crl_reason):
    asn1enum = backend._lib.ASN1_ENUMERATED_new()
    backend.openssl_assert(asn1enum != backend._ffi.NULL)
    asn1enum = backend._ffi.gc(asn1enum, backend._lib.ASN1_ENUMERATED_free)
    res = backend._lib.ASN1_ENUMERATED_set(
        asn1enum, _CRL_ENTRY_REASON_ENUM_TO_CODE[crl_reason.reason]
    )
    backend.openssl_assert(res == 1)

    return asn1enum


def _encode_invalidity_date(backend, invalidity_date):
    time = backend._lib.ASN1_GENERALIZEDTIME_set(
        backend._ffi.NULL, calendar.timegm(
            invalidity_date.invalidity_date.timetuple()
        )
    )
    backend.openssl_assert(time != backend._ffi.NULL)
    time = backend._ffi.gc(time, backend._lib.ASN1_GENERALIZEDTIME_free)

    return time


def _encode_certificate_policies(backend, certificate_policies):
    cp = backend._lib.sk_POLICYINFO_new_null()
    backend.openssl_assert(cp != backend._ffi.NULL)
    cp = backend._ffi.gc(cp, backend._lib.sk_POLICYINFO_free)
    for policy_info in certificate_policies:
        pi = backend._lib.POLICYINFO_new()
        backend.openssl_assert(pi != backend._ffi.NULL)
        res = backend._lib.sk_POLICYINFO_push(cp, pi)
        backend.openssl_assert(res >= 1)
        oid = _txt2obj(backend, policy_info.policy_identifier.dotted_string)
        pi.policyid = oid
        if policy_info.policy_qualifiers:
            pqis = backend._lib.sk_POLICYQUALINFO_new_null()
            backend.openssl_assert(pqis != backend._ffi.NULL)
            for qualifier in policy_info.policy_qualifiers:
                pqi = backend._lib.POLICYQUALINFO_new()
                backend.openssl_assert(pqi != backend._ffi.NULL)
                res = backend._lib.sk_POLICYQUALINFO_push(pqis, pqi)
                backend.openssl_assert(res >= 1)
                if isinstance(qualifier, six.text_type):
                    pqi.pqualid = _txt2obj(
                        backend, x509.OID_CPS_QUALIFIER.dotted_string
                    )
                    pqi.d.cpsuri = _encode_asn1_str(
                        backend,
                        qualifier.encode("ascii"),
                        len(qualifier.encode("ascii"))
                    )
                else:
                    assert isinstance(qualifier, x509.UserNotice)
                    pqi.pqualid = _txt2obj(
                        backend, x509.OID_CPS_USER_NOTICE.dotted_string
                    )
                    un = backend._lib.USERNOTICE_new()
                    backend.openssl_assert(un != backend._ffi.NULL)
                    pqi.d.usernotice = un
                    if qualifier.explicit_text:
                        un.exptext = _encode_asn1_utf8_str(
                            backend, qualifier.explicit_text
                        )

                    un.noticeref = _encode_notice_reference(
                        backend, qualifier.notice_reference
                    )

            pi.qualifiers = pqis

    return cp


def _encode_notice_reference(backend, notice):
    if notice is None:
        return backend._ffi.NULL
    else:
        nr = backend._lib.NOTICEREF_new()
        backend.openssl_assert(nr != backend._ffi.NULL)
        # organization is a required field
        nr.organization = _encode_asn1_utf8_str(backend, notice.organization)

        notice_stack = backend._lib.sk_ASN1_INTEGER_new_null()
        nr.noticenos = notice_stack
        for number in notice.notice_numbers:
            num = _encode_asn1_int(backend, number)
            res = backend._lib.sk_ASN1_INTEGER_push(notice_stack, num)
            backend.openssl_assert(res >= 1)

        return nr


def _txt2obj(backend, name):
    """
    Converts a Python string with an ASN.1 object ID in dotted form to a
    ASN1_OBJECT.
    """
    name = name.encode('ascii')
    obj = backend._lib.OBJ_txt2obj(name, 1)
    backend.openssl_assert(obj != backend._ffi.NULL)
    return obj


def _txt2obj_gc(backend, name):
    obj = _txt2obj(backend, name)
    obj = backend._ffi.gc(obj, backend._lib.ASN1_OBJECT_free)
    return obj


def _encode_ocsp_nocheck(backend, ext):
    """
    The OCSP No Check extension is defined as a null ASN.1 value embedded in
    an ASN.1 string.
    """
    return _encode_asn1_str_gc(backend, b"\x05\x00", 2)


def _encode_key_usage(backend, key_usage):
    set_bit = backend._lib.ASN1_BIT_STRING_set_bit
    ku = backend._lib.ASN1_BIT_STRING_new()
    ku = backend._ffi.gc(ku, backend._lib.ASN1_BIT_STRING_free)
    res = set_bit(ku, 0, key_usage.digital_signature)
    backend.openssl_assert(res == 1)
    res = set_bit(ku, 1, key_usage.content_commitment)
    backend.openssl_assert(res == 1)
    res = set_bit(ku, 2, key_usage.key_encipherment)
    backend.openssl_assert(res == 1)
    res = set_bit(ku, 3, key_usage.data_encipherment)
    backend.openssl_assert(res == 1)
    res = set_bit(ku, 4, key_usage.key_agreement)
    backend.openssl_assert(res == 1)
    res = set_bit(ku, 5, key_usage.key_cert_sign)
    backend.openssl_assert(res == 1)
    res = set_bit(ku, 6, key_usage.crl_sign)
    backend.openssl_assert(res == 1)
    if key_usage.key_agreement:
        res = set_bit(ku, 7, key_usage.encipher_only)
        backend.openssl_assert(res == 1)
        res = set_bit(ku, 8, key_usage.decipher_only)
        backend.openssl_assert(res == 1)
    else:
        res = set_bit(ku, 7, 0)
        backend.openssl_assert(res == 1)
        res = set_bit(ku, 8, 0)
        backend.openssl_assert(res == 1)

    return ku


def _encode_authority_key_identifier(backend, authority_keyid):
    akid = backend._lib.AUTHORITY_KEYID_new()
    backend.openssl_assert(akid != backend._ffi.NULL)
    akid = backend._ffi.gc(akid, backend._lib.AUTHORITY_KEYID_free)
    if authority_keyid.key_identifier is not None:
        akid.keyid = _encode_asn1_str(
            backend,
            authority_keyid.key_identifier,
            len(authority_keyid.key_identifier)
        )

    if authority_keyid.authority_cert_issuer is not None:
        akid.issuer = _encode_general_names(
            backend, authority_keyid.authority_cert_issuer
        )

    if authority_keyid.authority_cert_serial_number is not None:
        akid.serial = _encode_asn1_int(
            backend, authority_keyid.authority_cert_serial_number
        )

    return akid


def _encode_basic_constraints(backend, basic_constraints):
    constraints = backend._lib.BASIC_CONSTRAINTS_new()
    constraints = backend._ffi.gc(
        constraints, backend._lib.BASIC_CONSTRAINTS_free
    )
    constraints.ca = 255 if basic_constraints.ca else 0
    if basic_constraints.ca and basic_constraints.path_length is not None:
        constraints.pathlen = _encode_asn1_int(
            backend, basic_constraints.path_length
        )

    return constraints


def _encode_authority_information_access(backend, authority_info_access):
    aia = backend._lib.sk_ACCESS_DESCRIPTION_new_null()
    backend.openssl_assert(aia != backend._ffi.NULL)
    aia = backend._ffi.gc(
        aia, backend._lib.sk_ACCESS_DESCRIPTION_free
    )
    for access_description in authority_info_access:
        ad = backend._lib.ACCESS_DESCRIPTION_new()
        method = _txt2obj(
            backend, access_description.access_method.dotted_string
        )
        gn = _encode_general_name(backend, access_description.access_location)
        ad.method = method
        ad.location = gn
        res = backend._lib.sk_ACCESS_DESCRIPTION_push(aia, ad)
        backend.openssl_assert(res >= 1)

    return aia


def _encode_general_names(backend, names):
    general_names = backend._lib.GENERAL_NAMES_new()
    backend.openssl_assert(general_names != backend._ffi.NULL)
    for name in names:
        gn = _encode_general_name(backend, name)
        res = backend._lib.sk_GENERAL_NAME_push(general_names, gn)
        backend.openssl_assert(res != 0)

    return general_names


def _encode_alt_name(backend, san):
    general_names = _encode_general_names(backend, san)
    general_names = backend._ffi.gc(
        general_names, backend._lib.GENERAL_NAMES_free
    )
    return general_names


def _encode_subject_key_identifier(backend, ski):
    return _encode_asn1_str_gc(backend, ski.digest, len(ski.digest))


def _encode_general_name(backend, name):
    if isinstance(name, x509.DNSName):
        gn = backend._lib.GENERAL_NAME_new()
        backend.openssl_assert(gn != backend._ffi.NULL)
        gn.type = backend._lib.GEN_DNS

        ia5 = backend._lib.ASN1_IA5STRING_new()
        backend.openssl_assert(ia5 != backend._ffi.NULL)

        if name.value.startswith(u"*."):
            value = b"*." + idna.encode(name.value[2:])
        else:
            value = idna.encode(name.value)

        res = backend._lib.ASN1_STRING_set(ia5, value, len(value))
        backend.openssl_assert(res == 1)
        gn.d.dNSName = ia5
    elif isinstance(name, x509.RegisteredID):
        gn = backend._lib.GENERAL_NAME_new()
        backend.openssl_assert(gn != backend._ffi.NULL)
        gn.type = backend._lib.GEN_RID
        obj = backend._lib.OBJ_txt2obj(
            name.value.dotted_string.encode('ascii'), 1
        )
        backend.openssl_assert(obj != backend._ffi.NULL)
        gn.d.registeredID = obj
    elif isinstance(name, x509.DirectoryName):
        gn = backend._lib.GENERAL_NAME_new()
        backend.openssl_assert(gn != backend._ffi.NULL)
        dir_name = _encode_name(backend, name.value)
        gn.type = backend._lib.GEN_DIRNAME
        gn.d.directoryName = dir_name
    elif isinstance(name, x509.IPAddress):
        gn = backend._lib.GENERAL_NAME_new()
        backend.openssl_assert(gn != backend._ffi.NULL)
        ipaddr = _encode_asn1_str(
            backend, name.value.packed, len(name.value.packed)
        )
        gn.type = backend._lib.GEN_IPADD
        gn.d.iPAddress = ipaddr
    elif isinstance(name, x509.OtherName):
        gn = backend._lib.GENERAL_NAME_new()
        backend.openssl_assert(gn != backend._ffi.NULL)
        other_name = backend._lib.OTHERNAME_new()
        backend.openssl_assert(other_name != backend._ffi.NULL)

        type_id = backend._lib.OBJ_txt2obj(
            name.type_id.dotted_string.encode('ascii'), 1
        )
        backend.openssl_assert(type_id != backend._ffi.NULL)
        data = backend._ffi.new("unsigned char[]", name.value)
        data_ptr_ptr = backend._ffi.new("unsigned char **")
        data_ptr_ptr[0] = data
        value = backend._lib.d2i_ASN1_TYPE(
            backend._ffi.NULL, data_ptr_ptr, len(name.value)
        )
        if value == backend._ffi.NULL:
            backend._consume_errors()
            raise ValueError("Invalid ASN.1 data")
        other_name.type_id = type_id
        other_name.value = value
        gn.type = backend._lib.GEN_OTHERNAME
        gn.d.otherName = other_name
    elif isinstance(name, x509.RFC822Name):
        gn = backend._lib.GENERAL_NAME_new()
        backend.openssl_assert(gn != backend._ffi.NULL)
        asn1_str = _encode_asn1_str(
            backend, name._encoded, len(name._encoded)
        )
        gn.type = backend._lib.GEN_EMAIL
        gn.d.rfc822Name = asn1_str
    elif isinstance(name, x509.UniformResourceIdentifier):
        gn = backend._lib.GENERAL_NAME_new()
        backend.openssl_assert(gn != backend._ffi.NULL)
        asn1_str = _encode_asn1_str(
            backend, name._encoded, len(name._encoded)
        )
        gn.type = backend._lib.GEN_URI
        gn.d.uniformResourceIdentifier = asn1_str
    else:
        raise ValueError(
            "{0} is an unknown GeneralName type".format(name)
        )

    return gn


def _encode_extended_key_usage(backend, extended_key_usage):
    eku = backend._lib.sk_ASN1_OBJECT_new_null()
    eku = backend._ffi.gc(eku, backend._lib.sk_ASN1_OBJECT_free)
    for oid in extended_key_usage:
        obj = _txt2obj(backend, oid.dotted_string)
        res = backend._lib.sk_ASN1_OBJECT_push(eku, obj)
        backend.openssl_assert(res >= 1)

    return eku


_CRLREASONFLAGS = {
    x509.ReasonFlags.key_compromise: 1,
    x509.ReasonFlags.ca_compromise: 2,
    x509.ReasonFlags.affiliation_changed: 3,
    x509.ReasonFlags.superseded: 4,
    x509.ReasonFlags.cessation_of_operation: 5,
    x509.ReasonFlags.certificate_hold: 6,
    x509.ReasonFlags.privilege_withdrawn: 7,
    x509.ReasonFlags.aa_compromise: 8,
}


def _encode_crl_distribution_points(backend, crl_distribution_points):
    cdp = backend._lib.sk_DIST_POINT_new_null()
    cdp = backend._ffi.gc(cdp, backend._lib.sk_DIST_POINT_free)
    for point in crl_distribution_points:
        dp = backend._lib.DIST_POINT_new()
        backend.openssl_assert(dp != backend._ffi.NULL)

        if point.reasons:
            bitmask = backend._lib.ASN1_BIT_STRING_new()
            backend.openssl_assert(bitmask != backend._ffi.NULL)
            dp.reasons = bitmask
            for reason in point.reasons:
                res = backend._lib.ASN1_BIT_STRING_set_bit(
                    bitmask, _CRLREASONFLAGS[reason], 1
                )
                backend.openssl_assert(res == 1)

        if point.full_name:
            dpn = backend._lib.DIST_POINT_NAME_new()
            backend.openssl_assert(dpn != backend._ffi.NULL)
            dpn.type = _DISTPOINT_TYPE_FULLNAME
            dpn.name.fullname = _encode_general_names(backend, point.full_name)
            dp.distpoint = dpn

        if point.relative_name:
            dpn = backend._lib.DIST_POINT_NAME_new()
            backend.openssl_assert(dpn != backend._ffi.NULL)
            dpn.type = _DISTPOINT_TYPE_RELATIVENAME
            relativename = _encode_sk_name_entry(backend, point.relative_name)
            backend.openssl_assert(relativename != backend._ffi.NULL)
            dpn.name.relativename = relativename
            dp.distpoint = dpn

        if point.crl_issuer:
            dp.CRLissuer = _encode_general_names(backend, point.crl_issuer)

        res = backend._lib.sk_DIST_POINT_push(cdp, dp)
        backend.openssl_assert(res >= 1)

    return cdp


def _encode_name_constraints(backend, name_constraints):
    nc = backend._lib.NAME_CONSTRAINTS_new()
    backend.openssl_assert(nc != backend._ffi.NULL)
    nc = backend._ffi.gc(nc, backend._lib.NAME_CONSTRAINTS_free)
    permitted = _encode_general_subtree(
        backend, name_constraints.permitted_subtrees
    )
    nc.permittedSubtrees = permitted
    excluded = _encode_general_subtree(
        backend, name_constraints.excluded_subtrees
    )
    nc.excludedSubtrees = excluded

    return nc


def _encode_general_subtree(backend, subtrees):
    if subtrees is None:
        return backend._ffi.NULL
    else:
        general_subtrees = backend._lib.sk_GENERAL_SUBTREE_new_null()
        for name in subtrees:
            gs = backend._lib.GENERAL_SUBTREE_new()
            gs.base = _encode_general_name(backend, name)
            res = backend._lib.sk_GENERAL_SUBTREE_push(general_subtrees, gs)
            assert res >= 1

        return general_subtrees


_EXTENSION_ENCODE_HANDLERS = {
    ExtensionOID.BASIC_CONSTRAINTS: _encode_basic_constraints,
    ExtensionOID.SUBJECT_KEY_IDENTIFIER: _encode_subject_key_identifier,
    ExtensionOID.KEY_USAGE: _encode_key_usage,
    ExtensionOID.SUBJECT_ALTERNATIVE_NAME: _encode_alt_name,
    ExtensionOID.ISSUER_ALTERNATIVE_NAME: _encode_alt_name,
    ExtensionOID.EXTENDED_KEY_USAGE: _encode_extended_key_usage,
    ExtensionOID.AUTHORITY_KEY_IDENTIFIER: _encode_authority_key_identifier,
    ExtensionOID.CERTIFICATE_POLICIES: _encode_certificate_policies,
    ExtensionOID.AUTHORITY_INFORMATION_ACCESS: (
        _encode_authority_information_access
    ),
    ExtensionOID.CRL_DISTRIBUTION_POINTS: _encode_crl_distribution_points,
    ExtensionOID.INHIBIT_ANY_POLICY: _encode_inhibit_any_policy,
    ExtensionOID.OCSP_NO_CHECK: _encode_ocsp_nocheck,
    ExtensionOID.NAME_CONSTRAINTS: _encode_name_constraints,
}

_CRL_EXTENSION_ENCODE_HANDLERS = {
    ExtensionOID.ISSUER_ALTERNATIVE_NAME: _encode_alt_name,
    ExtensionOID.AUTHORITY_KEY_IDENTIFIER: _encode_authority_key_identifier,
    ExtensionOID.AUTHORITY_INFORMATION_ACCESS: (
        _encode_authority_information_access
    ),
    ExtensionOID.CRL_NUMBER: _encode_crl_number,
}

_CRL_ENTRY_EXTENSION_ENCODE_HANDLERS = {
    CRLEntryExtensionOID.CERTIFICATE_ISSUER: _encode_alt_name,
    CRLEntryExtensionOID.CRL_REASON: _encode_crl_reason,
    CRLEntryExtensionOID.INVALIDITY_DATE: _encode_invalidity_date,
}