/*******************************************************************************

    D language bindings for libsodium's utils.h

    License: ISC (see LICENSE.txt)

*******************************************************************************/

module libsodium.utils;

@nogc nothrow:

import libsodium.export_;

extern (C):

extern (D) auto SODIUM_C99(T)(auto ref T X)
{
    return X;
}

void sodium_memzero (void* pnt, const size_t len);

void sodium_stackzero (const size_t len);

/*
 * WARNING: sodium_memcmp() must be used to verify if two secret keys
 * are equal, in constant time.
 * It returns 0 if the keys are equal, and -1 if they differ.
 * This function is not designed for lexicographical comparisons.
 */
int sodium_memcmp (const void* b1_, const void* b2_, size_t len);

/*
 * sodium_compare() returns -1 if b1_ < b2_, 1 if b1_ > b2_ and 0 if b1_ == b2_
 * It is suitable for lexicographical comparisons, or to compare nonces
 * and counters stored in little-endian format.
 * However, it is slower than sodium_memcmp().
 */
int sodium_compare (const(ubyte)* b1_, const(ubyte)* b2_, size_t len);

int sodium_is_zero (const(ubyte)* n, const size_t nlen);

void sodium_increment (ubyte* n, const size_t nlen);

void sodium_add (ubyte* a, const(ubyte)* b, const size_t len);

void sodium_sub (ubyte* a, const(ubyte)* b, const size_t len);

char* sodium_bin2hex (
    char* hex,
    const size_t hex_maxlen,
    const ubyte* bin,
    const size_t bin_len);

int sodium_hex2bin (
    ubyte* bin,
    const size_t bin_maxlen,
    const char* hex,
    const size_t hex_len,
    const char* ignore,
    size_t* bin_len,
    const char** hex_end);

enum sodium_base64_VARIANT_ORIGINAL = 1;
enum sodium_base64_VARIANT_ORIGINAL_NO_PADDING = 3;
enum sodium_base64_VARIANT_URLSAFE = 5;
enum sodium_base64_VARIANT_URLSAFE_NO_PADDING = 7;

/*
 * Computes the required length to encode BIN_LEN bytes as a base64 string
 * using the given variant. The computed length includes a trailing \0.
 */
extern (D) auto sodium_base64_ENCODED_LEN(T0, T1)(auto ref T0 BIN_LEN, auto ref T1 VARIANT)
{
    return (BIN_LEN / 3U) * 4U + (((BIN_LEN - (BIN_LEN / 3U) * 3U) | ((BIN_LEN - (BIN_LEN / 3U) * 3U) >> 1)) & 1U) * (4U - (~(((VARIANT & 2U) >> 1) - 1U) & (3U - (BIN_LEN - (BIN_LEN / 3U) * 3U)))) + 1U;
}

size_t sodium_base64_encoded_len (const size_t bin_len, const int variant);

char* sodium_bin2base64 (
    char* b64,
    const size_t b64_maxlen,
    const ubyte* bin,
    const size_t bin_len,
    const int variant);

int sodium_base642bin (
    ubyte* bin,
    const size_t bin_maxlen,
    const char* b64,
    const size_t b64_len,
    const char* ignore,
    size_t* bin_len,
    const char** b64_end,
    const int variant);

int sodium_mlock (void* addr, const size_t len);

int sodium_munlock (void* addr, const size_t len);

/* WARNING: sodium_malloc() and sodium_allocarray() are not general-purpose
 * allocation functions.
 *
 * They return a pointer to a region filled with 0xd0 bytes, immediately
 * followed by a guard page.
 * As a result, accessing a single byte after the requested allocation size
 * will intentionally trigger a segmentation fault.
 *
 * A canary and an additional guard page placed before the beginning of the
 * region may also kill the process if a buffer underflow is detected.
 *
 * The memory layout is:
 * [unprotected region size (read only)][guard page (no access)][unprotected pages (read/write)][guard page (no access)]
 * With the layout of the unprotected pages being:
 * [optional padding][16-bytes canary][user region]
 *
 * However:
 * - These functions are significantly slower than standard functions
 * - Each allocation requires 3 or 4 additional pages
 * - The returned address will not be aligned if the allocation size is not
 *   a multiple of the required alignment. For this reason, these functions
 *   are designed to store data, such as secret keys and messages.
 *
 * sodium_malloc() can be used to allocate any libsodium data structure.
 *
 * The crypto_generichash_state structure is packed and its length is
 * either 357 or 361 bytes. For this reason, when using sodium_malloc() to
 * allocate a crypto_generichash_state structure, padding must be added in
 * order to ensure proper alignment. crypto_generichash_statebytes()
 * returns the rounded up structure size, and should be prefered to sizeof():
 * state = sodium_malloc(crypto_generichash_statebytes());
 */

void* sodium_malloc (const size_t size);

void* sodium_allocarray (size_t count, size_t size);

void sodium_free (void* ptr);

int sodium_mprotect_noaccess (void* ptr);

int sodium_mprotect_readonly (void* ptr);

int sodium_mprotect_readwrite (void* ptr);

int sodium_pad (
    size_t* padded_buflen_p,
    ubyte* buf,
    size_t unpadded_buflen,
    size_t blocksize,
    size_t max_buflen);

int sodium_unpad (
    size_t* unpadded_buflen_p,
    const(ubyte)* buf,
    size_t padded_buflen,
    size_t blocksize);

/* -------- */

int _sodium_alloc_init ();