/*
 * asn1.h
 * ------
 * Library internal header file for ASN.1 routines.
 *
 * These functions are not part of the public libhal API.
 *
 * More than 20 years after it was written, the best simple
 * introduction to ASN.1 is still Burt Kalski's "A Layman's Guide to a
 * Subset of ASN.1, BER, and DER".  Ask your nearest search engine.
 *
 * Authors: Rob Austein
 * Copyright (c) 2015, SUNET
 *
 * Redistribution and use in source and binary forms, with or
 * without modification, are permitted provided that the following
 * conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef _HAL_ASN1_H_
#define _HAL_ASN1_H_

#include <stdint.h>
#include <stdlib.h>

#include <tfm.h>

#define ASN1_UNIVERSAL          0x00
#define ASN1_APPLICATION        0x40
#define ASN1_CONTEXT_SPECIFIC   0x80
#define ASN1_PRIVATE            0xC0

#define ASN1_PRIMITIVE          0x00
#define ASN1_CONSTRUCTED        0x20

#define ASN1_TAG_MASK           0x1F

#define ASN1_INTEGER            (ASN1_PRIMITIVE   | 0x02)
#define ASN1_BIT_STRING         (ASN1_PRIMITIVE   | 0x03)
#define ASN1_OCTET_STRING       (ASN1_PRIMITIVE   | 0x04)
#define ASN1_NULL               (ASN1_PRIMITIVE   | 0x05)
#define ASN1_OBJECT_IDENTIFIER  (ASN1_PRIMITIVE   | 0x06)
#define ASN1_SEQUENCE           (ASN1_CONSTRUCTED | 0x10)
#define ASN1_SET                (ASN1_CONSTRUCTED | 0x11)

#define ASN1_EXPLICIT_CONTEXT   (ASN1_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED)
#define ASN1_EXPLICIT_0         (ASN1_EXPLICIT_CONTEXT + 0)
#define ASN1_EXPLICIT_1         (ASN1_EXPLICIT_CONTEXT + 1)

/*
 * Functions to strip const qualifiers from arguments to libtfm calls
 * in a relatively type-safe manner.  These don't really have anything
 * to do with ASN.1 per se, but all the code that needs them reads
 * this header file, so this is the simplest place to put them.
 */

static inline fp_int *unconst_fp_int(const fp_int * const arg)
{
  return (fp_int *) arg;
}

static inline uint8_t *unconst_uint8_t(const uint8_t * const arg)
{
  return (uint8_t *) arg;
}

extern hal_error_t hal_asn1_encode_header(const uint8_t tag,
                                          const size_t value_len,
                                          uint8_t *der, size_t *der_len, const size_t der_max);

extern hal_error_t hal_asn1_decode_header(const uint8_t tag,
                                          const uint8_t * const der, size_t der_max,
                                          size_t *hlen, size_t *vlen);

extern hal_error_t hal_asn1_encode_integer(const fp_int * const bn,
                                           uint8_t *der, size_t *der_len, const size_t der_max);

extern hal_error_t hal_asn1_decode_integer(fp_int *bn,
                                           const uint8_t * const der, size_t *der_len, const size_t der_max);

#endif /* _HAL_ASN1_H_ */

/*
 * Local variables:
 * indent-tabs-mode: nil
 * End:
 */