x509.py 文件源码

def _decode_basic_constraints(backend, bc_st):
    basic_constraints = backend._ffi.cast("BASIC_CONSTRAINTS *", bc_st)
    basic_constraints = backend._ffi.gc(
        basic_constraints, backend._lib.BASIC_CONSTRAINTS_free
    )
    # The byte representation of an ASN.1 boolean true is \xff. OpenSSL
    # chooses to just map this to its ordinal value, so true is 255 and
    # false is 0.
    ca = basic_constraints.ca == 255
    if basic_constraints.pathlen == backend._ffi.NULL:
        path_length = None
    else:
        path_length = backend._asn1_integer_to_int(basic_constraints.pathlen)

    return x509.BasicConstraints(ca, path_length)