/*

 * Copyright 1995-2020 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the OpenSSL license (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include "internal/cryptlib.h"

#include <openssl/hmac.h>

#include <openssl/opensslconf.h>

#include "hmac_local.h"

int HMAC_Init_ex(HMAC_CTX *ctx, const void *key, int len,

                 const EVP_MD *md, ENGINE *impl)

{

    int rv = 0, reset = 0;

    int i, j;

    unsigned char pad[HMAC_MAX_MD_CBLOCK_SIZE];

    unsigned int keytmp_length;

    unsigned char keytmp[HMAC_MAX_MD_CBLOCK_SIZE];

    /* If we are changing MD then we must have a key */

    if (md != NULL && md != ctx->md && (key == NULL || len < 0))

        return 0;

    if (md != NULL) {

        ctx->md = md;

    } else if (ctx->md) {

        md = ctx->md;

    } else {

        return 0;

    }

    /*

     * The HMAC construction is not allowed  to be used with the

     * extendable-output functions (XOF) shake128 and shake256.

     */

    if ((EVP_MD_meth_get_flags(md) & EVP_MD_FLAG_XOF) != 0)

        return 0;

    if (key != NULL) {

        reset = 1;

        j = EVP_MD_block_size(md);

        if (!ossl_assert(j <= (int)sizeof(keytmp)))

            return 0;

        if (j < len) {

            if (!EVP_DigestInit_ex(ctx->md_ctx, md, impl)

                    || !EVP_DigestUpdate(ctx->md_ctx, key, len)

                    || !EVP_DigestFinal_ex(ctx->md_ctx, keytmp,

                                           &keytmp_length))

                return 0;

        } else {

            if (len < 0 || len > (int)sizeof(keytmp))

                return 0;

            memcpy(keytmp, key, len);

            keytmp_length = len;

        }

        if (keytmp_length != HMAC_MAX_MD_CBLOCK_SIZE)

            memset(&keytmp[keytmp_length], 0,

                   HMAC_MAX_MD_CBLOCK_SIZE - keytmp_length);

        for (i = 0; i < HMAC_MAX_MD_CBLOCK_SIZE; i++)

            pad[i] = 0x36 ^ keytmp[i];

        if (!EVP_DigestInit_ex(ctx->i_ctx, md, impl)

                || !EVP_DigestUpdate(ctx->i_ctx, pad, EVP_MD_block_size(md)))

            goto err;

        for (i = 0; i < HMAC_MAX_MD_CBLOCK_SIZE; i++)

            pad[i] = 0x5c ^ keytmp[i];

        if (!EVP_DigestInit_ex(ctx->o_ctx, md, impl)

                || !EVP_DigestUpdate(ctx->o_ctx, pad, EVP_MD_block_size(md)))

            goto err;

    }

    if (!EVP_MD_CTX_copy_ex(ctx->md_ctx, ctx->i_ctx))

        goto err;

    rv = 1;

 err:

    if (reset) {

        OPENSSL_cleanse(keytmp, sizeof(keytmp));

        OPENSSL_cleanse(pad, sizeof(pad));

    }

    return rv;

}

#if OPENSSL_API_COMPAT < 0x10100000L

int HMAC_Init(HMAC_CTX *ctx, const void *key, int len, const EVP_MD *md)

{

    if (key && md)

        HMAC_CTX_reset(ctx);

    return HMAC_Init_ex(ctx, key, len, md, NULL);

}

#endif

int HMAC_Update(HMAC_CTX *ctx, const unsigned char *data, size_t len)

{

    if (!ctx->md)

        return 0;

    return EVP_DigestUpdate(ctx->md_ctx, data, len);

}

int HMAC_Final(HMAC_CTX *ctx, unsigned char *md, unsigned int *len)

{

    unsigned int i;

    unsigned char buf[EVP_MAX_MD_SIZE];

    if (!ctx->md)

        goto err;

    if (!EVP_DigestFinal_ex(ctx->md_ctx, buf, &i))

        goto err;

    if (!EVP_MD_CTX_copy_ex(ctx->md_ctx, ctx->o_ctx))

        goto err;

    if (!EVP_DigestUpdate(ctx->md_ctx, buf, i))

        goto err;

    if (!EVP_DigestFinal_ex(ctx->md_ctx, md, len))

        goto err;

    return 1;

 err:

    return 0;

}

size_t HMAC_size(const HMAC_CTX *ctx)

{

    int size = EVP_MD_size((ctx)->md);

    return (size < 0) ? 0 : size;

}

HMAC_CTX *HMAC_CTX_new(void)

{

    HMAC_CTX *ctx = OPENSSL_zalloc(sizeof(HMAC_CTX));

    if (ctx != NULL) {

        if (!HMAC_CTX_reset(ctx)) {

            HMAC_CTX_free(ctx);

            return NULL;

        }

    }

    return ctx;

}

static void hmac_ctx_cleanup(HMAC_CTX *ctx)

{

    EVP_MD_CTX_reset(ctx->i_ctx);

    EVP_MD_CTX_reset(ctx->o_ctx);

    EVP_MD_CTX_reset(ctx->md_ctx);

    ctx->md = NULL;

}

void HMAC_CTX_free(HMAC_CTX *ctx)

{

    if (ctx != NULL) {

        hmac_ctx_cleanup(ctx);

        EVP_MD_CTX_free(ctx->i_ctx);

        EVP_MD_CTX_free(ctx->o_ctx);

        EVP_MD_CTX_free(ctx->md_ctx);

        OPENSSL_free(ctx);

    }

}

static int hmac_ctx_alloc_mds(HMAC_CTX *ctx)

{

    if (ctx->i_ctx == NULL)

        ctx->i_ctx = EVP_MD_CTX_new();

    if (ctx->i_ctx == NULL)

        return 0;

    if (ctx->o_ctx == NULL)

        ctx->o_ctx = EVP_MD_CTX_new();

    if (ctx->o_ctx == NULL)

        return 0;

    if (ctx->md_ctx == NULL)

        ctx->md_ctx = EVP_MD_CTX_new();

    if (ctx->md_ctx == NULL)

        return 0;

    return 1;

}

int HMAC_CTX_reset(HMAC_CTX *ctx)

{

    hmac_ctx_cleanup(ctx);

    if (!hmac_ctx_alloc_mds(ctx)) {

        hmac_ctx_cleanup(ctx);

        return 0;

    }

    return 1;

}

int HMAC_CTX_copy(HMAC_CTX *dctx, HMAC_CTX *sctx)

{

    if (!hmac_ctx_alloc_mds(dctx))

        goto err;

    if (!EVP_MD_CTX_copy_ex(dctx->i_ctx, sctx->i_ctx))

        goto err;

    if (!EVP_MD_CTX_copy_ex(dctx->o_ctx, sctx->o_ctx))

        goto err;

    if (!EVP_MD_CTX_copy_ex(dctx->md_ctx, sctx->md_ctx))

        goto err;

    dctx->md = sctx->md;

    return 1;

 err:

    hmac_ctx_cleanup(dctx);

    return 0;

}

unsigned char *HMAC(const EVP_MD *evp_md, const void *key, int key_len,

                    const unsigned char *d, size_t n, unsigned char *md,

                    unsigned int *md_len)

{

    HMAC_CTX *c = NULL;

    static unsigned char m[EVP_MAX_MD_SIZE];

    static const unsigned char dummy_key[1] = {'\0'};

    if (md == NULL)

        md = m;

    if ((c = HMAC_CTX_new()) == NULL)

        goto err;

    /* For HMAC_Init_ex, NULL key signals reuse. */

    if (key == NULL && key_len == 0) {

        key = dummy_key;

    }

    if (!HMAC_Init_ex(c, key, key_len, evp_md, NULL))

        goto err;

    if (!HMAC_Update(c, d, n))

        goto err;

    if (!HMAC_Final(c, md, md_len))

        goto err;

    HMAC_CTX_free(c);

    return md;

 err:

    HMAC_CTX_free(c);

    return NULL;

}

void HMAC_CTX_set_flags(HMAC_CTX *ctx, unsigned long flags)

{

    EVP_MD_CTX_set_flags(ctx->i_ctx, flags);

    EVP_MD_CTX_set_flags(ctx->o_ctx, flags);

    EVP_MD_CTX_set_flags(ctx->md_ctx, flags);

}

const EVP_MD *HMAC_CTX_get_md(const HMAC_CTX *ctx)

{

    return ctx->md;

}