#include <arpa/inet.h>
#include <string.h>
#include <openssl/evp.h>
#include <openssl/hmac.h>

#include "gost_lcl.h"
#include "e_gost_err.h"

/*
 * Function expects that out is a preallocated buffer of length
 * defined as sum of shared_len and mac length defined by mac_nid
 * */
int gost_kexp15(const unsigned char *shared_key, const int shared_len,
                int cipher_nid, const unsigned char *cipher_key,
                int mac_nid, unsigned char *mac_key,
                const unsigned char *iv, const size_t ivlen,
                unsigned char *out, int *out_len)
{
    unsigned char iv_full[16], mac_buf[16];
    unsigned int mac_len;

    EVP_CIPHER_CTX *ciph = NULL;
    EVP_MD_CTX *mac = NULL;

    int ret = 0;
    int len;

    mac_len = (cipher_nid == NID_magma_ctr) ? 8 :
        (cipher_nid == NID_grasshopper_ctr) ? 16 : 0;

    if (mac_len == 0) {
        GOSTerr(GOST_F_GOST_KEXP15, GOST_R_INVALID_CIPHER);
        goto err;
    }

    /* we expect IV of half length */
    memset(iv_full, 0, 16);
    memcpy(iv_full, iv, ivlen);

    mac = EVP_MD_CTX_new();
    if (mac == NULL) {
        GOSTerr(GOST_F_GOST_KEXP15, ERR_R_MALLOC_FAILURE);
        goto err;
    }

    if (EVP_DigestInit_ex(mac, EVP_get_digestbynid(mac_nid), NULL) <= 0
        || EVP_MD_CTX_ctrl(mac, EVP_MD_CTRL_SET_KEY, 32, mac_key) <= 0
        || EVP_MD_CTX_ctrl(mac, EVP_MD_CTRL_MAC_LEN, mac_len, NULL) <= 0
        || EVP_DigestUpdate(mac, iv, ivlen) <= 0
        || EVP_DigestUpdate(mac, shared_key, shared_len) <= 0
        /* As we set MAC length directly, we should not allow overwriting it */
        || EVP_DigestFinal_ex(mac, mac_buf, NULL) <= 0) {
        GOSTerr(GOST_F_GOST_KEXP15, ERR_R_INTERNAL_ERROR);
        goto err;
    }

    ciph = EVP_CIPHER_CTX_new();
    if (ciph == NULL) {
        GOSTerr(GOST_F_GOST_KEXP15, ERR_R_MALLOC_FAILURE);
        goto err;
    }

    if (EVP_CipherInit_ex
        (ciph, EVP_get_cipherbynid(cipher_nid), NULL, NULL, NULL, 1) <= 0
        || EVP_CipherInit_ex(ciph, NULL, NULL, cipher_key, iv_full, 1) <= 0
        || EVP_CipherUpdate(ciph, out, &len, shared_key, shared_len) <= 0
        || EVP_CipherUpdate(ciph, out + shared_len, &len, mac_buf, mac_len) <= 0
        || EVP_CipherFinal_ex(ciph, out + shared_len + len, out_len) <= 0) {
        GOSTerr(GOST_F_GOST_KEXP15, ERR_R_INTERNAL_ERROR);
        goto err;
    }

    *out_len = shared_len + mac_len;

    ret = 1;

 err:
    OPENSSL_cleanse(mac_buf, mac_len);
    EVP_MD_CTX_free(mac);
    EVP_CIPHER_CTX_free(ciph);

    return ret;
}

/*
 * Function expects that shared_key is a preallocated buffer
 * with length defined as expkeylen - mac_len defined by mac_nid
 * */
int gost_kimp15(const unsigned char *expkey, const size_t expkeylen,
                int cipher_nid, const unsigned char *cipher_key,
                int mac_nid, unsigned char *mac_key,
                const unsigned char *iv, const size_t ivlen,
                unsigned char *shared_key)
{
    unsigned char iv_full[16], out[48], mac_buf[16];
    unsigned int mac_len;
    const size_t shared_len = 32;

    EVP_CIPHER_CTX *ciph = NULL;
    EVP_MD_CTX *mac = NULL;

    int ret = 0;
    int len;

    mac_len = (cipher_nid == NID_magma_ctr) ? 8 :
        (cipher_nid == NID_grasshopper_ctr) ? 16 : 0;

    if (mac_len == 0) {
        GOSTerr(GOST_F_GOST_KIMP15, GOST_R_INVALID_CIPHER);
        goto err;
    }

    /* we expect IV of half length */
    memset(iv_full, 0, 16);
    memcpy(iv_full, iv, ivlen);

    ciph = EVP_CIPHER_CTX_new();
    if (ciph == NULL) {
        GOSTerr(GOST_F_GOST_KIMP15, ERR_R_MALLOC_FAILURE);
        goto err;
    }

    if (EVP_CipherInit_ex
        (ciph, EVP_get_cipherbynid(cipher_nid), NULL, NULL, NULL, 0) <= 0
        || EVP_CipherInit_ex(ciph, NULL, NULL, cipher_key, iv_full, 0) <= 0
        || EVP_CipherUpdate(ciph, out, &len, expkey, expkeylen) <= 0
        || EVP_CipherFinal_ex(ciph, out + len, &len) <= 0) {
        GOSTerr(GOST_F_GOST_KIMP15, ERR_R_INTERNAL_ERROR);
        goto err;
    }
    /*Now we have shared key and mac in out[] */

    mac = EVP_MD_CTX_new();
    if (mac == NULL) {
        GOSTerr(GOST_F_GOST_KIMP15, ERR_R_MALLOC_FAILURE);
        goto err;
    }

    if (EVP_DigestInit_ex(mac, EVP_get_digestbynid(mac_nid), NULL) <= 0
        || EVP_MD_CTX_ctrl(mac, EVP_MD_CTRL_SET_KEY, 32, mac_key) <= 0
        || EVP_MD_CTX_ctrl(mac, EVP_MD_CTRL_MAC_LEN, mac_len, NULL) <= 0
        || EVP_DigestUpdate(mac, iv, ivlen) <= 0
        || EVP_DigestUpdate(mac, out, shared_len) <= 0
        /* As we set MAC length directly, we should not allow overwriting it */
        || EVP_DigestFinal_ex(mac, mac_buf, NULL) <= 0) {
        GOSTerr(GOST_F_GOST_KIMP15, ERR_R_INTERNAL_ERROR);
        goto err;
    }

    if (CRYPTO_memcmp(mac_buf, out + shared_len, mac_len) != 0) {
        GOSTerr(GOST_F_GOST_KIMP15, GOST_R_BAD_MAC);
        goto err;
    }

    memcpy(shared_key, out, shared_len);
    ret = 1;

 err:
    OPENSSL_cleanse(out, sizeof(out));
    EVP_MD_CTX_free(mac);
    EVP_CIPHER_CTX_free(ciph);
    return ret;
}

int gost_kdftree2012_256(unsigned char *keyout, size_t keyout_len,
                         const unsigned char *key, size_t keylen,
                         const unsigned char *label, size_t label_len,
                         const unsigned char *seed, size_t seed_len,
                         const size_t representation)
{
    int iters, i = 0;
    unsigned char zero = 0;
    unsigned char *ptr = keyout;
    HMAC_CTX *ctx = NULL;
    unsigned char *len_ptr = NULL;
    uint32_t len_repr = htonl(keyout_len * 8);
    size_t len_repr_len = 4;

    ctx = HMAC_CTX_new();
    if (ctx == NULL) {
        GOSTerr(GOST_F_GOST_KDFTREE2012_256, ERR_R_MALLOC_FAILURE);
        return 0;
    }

    if ((keyout_len == 0) || (keyout_len % 32 != 0)) {
        GOSTerr(GOST_F_GOST_KDFTREE2012_256, ERR_R_INTERNAL_ERROR);
        return 0;
    }
    iters = keyout_len / 32;

    len_ptr = (unsigned char *)&len_repr;
    while (*len_ptr == 0) {
        len_ptr++;
        len_repr_len--;
    }

    for (i = 1; i <= iters; i++) {
        uint32_t iter_net = htonl(i);
        unsigned char *rep_ptr =
            ((unsigned char *)&iter_net) + (4 - representation);

        if (HMAC_Init_ex(ctx, key, keylen,
                         EVP_get_digestbynid(NID_id_GostR3411_2012_256),
                         NULL) <= 0
            || HMAC_Update(ctx, rep_ptr, representation) <= 0
            || HMAC_Update(ctx, label, label_len) <= 0
            || HMAC_Update(ctx, &zero, 1) <= 0
            || HMAC_Update(ctx, seed, seed_len) <= 0
            || HMAC_Update(ctx, len_ptr, len_repr_len) <= 0
            || HMAC_Final(ctx, ptr, NULL) <= 0) {
            GOSTerr(GOST_F_GOST_KDFTREE2012_256, ERR_R_INTERNAL_ERROR);
            HMAC_CTX_free(ctx);
            return 0;
        }

        HMAC_CTX_reset(ctx);
        ptr += 32;
    }

    HMAC_CTX_free(ctx);

    return 1;
}

#ifdef ENABLE_UNIT_TESTS
# include <stdio.h>
# include <string.h>
# include <openssl/obj_mac.h>

static void hexdump(FILE *f, const char *title, const unsigned char *s, int l)
{
    int n = 0;

    fprintf(f, "%s", title);
    for (; n < l; ++n) {
        if ((n % 16) == 0)
            fprintf(f, "\n%04x", n);
        fprintf(f, " %02x", s[n]);
    }
    fprintf(f, "\n");
}

int main(void)
{
    const unsigned char shared_key[] = {
        0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF,
        0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
        0xFE, 0xDC, 0xBA, 0x98, 0x76, 0x54, 0x32, 0x10,
        0x01, 0x23, 0x45, 0x67, 0x89, 0xAB, 0xCD, 0xEF
    };

    const unsigned char magma_key[] = {
        0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
        0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F,
        0x38, 0x39, 0x3A, 0x3B, 0x3C, 0x3D, 0x3E, 0x3F,
        0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
    };

    unsigned char mac_magma_key[] = {
        0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
        0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
        0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
        0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F,
    };

    const unsigned char magma_iv[] = { 0x67, 0xBE, 0xD6, 0x54 };

    const unsigned char magma_export[] = {
        0xCF, 0xD5, 0xA1, 0x2D, 0x5B, 0x81, 0xB6, 0xE1,
        0xE9, 0x9C, 0x91, 0x6D, 0x07, 0x90, 0x0C, 0x6A,
        0xC1, 0x27, 0x03, 0xFB, 0x3A, 0xBD, 0xED, 0x55,
        0x56, 0x7B, 0xF3, 0x74, 0x2C, 0x89, 0x9C, 0x75,
        0x5D, 0xAF, 0xE7, 0xB4, 0x2E, 0x3A, 0x8B, 0xD9
    };

    unsigned char kdftree_key[] = {
        0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
        0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F,
        0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
        0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F,
    };

    unsigned char kdf_label[] = { 0x26, 0xBD, 0xB8, 0x78 };
    unsigned char kdf_seed[] =
        { 0xAF, 0x21, 0x43, 0x41, 0x45, 0x65, 0x63, 0x78 };
    const unsigned char kdf_etalon[] = {
        0x22, 0xB6, 0x83, 0x78, 0x45, 0xC6, 0xBE, 0xF6,
        0x5E, 0xA7, 0x16, 0x72, 0xB2, 0x65, 0x83, 0x10,
        0x86, 0xD3, 0xC7, 0x6A, 0xEB, 0xE6, 0xDA, 0xE9,
        0x1C, 0xAD, 0x51, 0xD8, 0x3F, 0x79, 0xD1, 0x6B,
        0x07, 0x4C, 0x93, 0x30, 0x59, 0x9D, 0x7F, 0x8D,
        0x71, 0x2F, 0xCA, 0x54, 0x39, 0x2F, 0x4D, 0xDD,
        0xE9, 0x37, 0x51, 0x20, 0x6B, 0x35, 0x84, 0xC8,
        0xF4, 0x3F, 0x9E, 0x6D, 0xC5, 0x15, 0x31, 0xF9
    };

    unsigned char buf[32 + 16];
    int ret = 0;
    int outlen = 40;
    unsigned char kdf_result[64];

    OpenSSL_add_all_algorithms();
    memset(buf, 0, sizeof(buf));

    ret = gost_kexp15(shared_key, 32,
                      NID_magma_ctr, magma_key,
                      NID_magma_mac, mac_magma_key, magma_iv, 4, buf, &outlen);

    if (ret <= 0)
        ERR_print_errors_fp(stderr);
    else {
        hexdump(stdout, "Magma key export", buf, 40);
        if (memcmp(buf, magma_export, 40) != 0) {
            fprintf(stdout, "ERROR! test failed\n");
        }
    }

    ret = gost_kimp15(magma_export, 40,
                      NID_magma_ctr, magma_key,
                      NID_magma_mac, mac_magma_key, magma_iv, 4, buf);

    if (ret <= 0)
        ERR_print_errors_fp(stderr);
    else {
        hexdump(stdout, "Magma key import", buf, 32);
        if (memcmp(buf, shared_key, 32) != 0) {
            fprintf(stdout, "ERROR! test failed\n");
        }
    }

    ret = gost_kdftree2012_256(kdf_result, 64, kdftree_key, 32, kdf_label, 4,
                               kdf_seed, 8, 1);
    if (ret <= 0)
        ERR_print_errors_fp(stderr);
    else {
        hexdump(stdout, "KDF TREE", kdf_result, 64);
        if (memcmp(kdf_result, kdf_etalon, 64) != 0) {
            fprintf(stdout, "ERROR! test failed\n");
        }
    }

    return 0;
}

#endif