/*

 * Copyright 2002-2020 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the Apache License 2.0 (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 <string.h> /* strlen */

#include <openssl/crypto.h>

#include "ec_local.h"

static const char *HEX_DIGITS = "0123456789ABCDEF";

/* the return value must be freed (using OPENSSL_free()) */

char *EC_POINT_point2hex(const EC_GROUP *group,

                         const EC_POINT *point,

                         point_conversion_form_t form, BN_CTX *ctx)

{

    char *ret, *p;

    size_t buf_len = 0, i;

    unsigned char *buf = NULL, *pbuf;

    buf_len = EC_POINT_point2buf(group, point, form, &buf, ctx);

    if (buf_len == 0)

        return NULL;

    ret = OPENSSL_malloc(buf_len * 2 + 2);

    if (ret == NULL) {

        OPENSSL_free(buf);

        return NULL;

    }

    p = ret;

    pbuf = buf;

    for (i = buf_len; i > 0; i--) {

        int v = (int)*(pbuf++);

        *(p++) = HEX_DIGITS[v >> 4];

        *(p++) = HEX_DIGITS[v & 0x0F];

    }

    *p = '\0';

    OPENSSL_free(buf);

    return ret;

}

EC_POINT *EC_POINT_hex2point(const EC_GROUP *group,

                             const char *hex, EC_POINT *point, BN_CTX *ctx)

{

    int ok = 0;

    unsigned char *oct_buf = NULL;

    size_t len, oct_buf_len = 0;

    EC_POINT *pt = NULL;

    if (group == NULL || hex == NULL)

        return NULL;

    if (point == NULL) {

        pt = EC_POINT_new(group);

        if (pt == NULL)

            goto err;

    } else {

        pt = point;

    }

    len = strlen(hex) / 2;

    oct_buf = OPENSSL_malloc(len);

    if (oct_buf == NULL)

        goto err;

    if (!OPENSSL_hexstr2buf_ex(oct_buf, len, &oct_buf_len, hex, '\0')

        || !EC_POINT_oct2point(group, pt, oct_buf, oct_buf_len, ctx))

        goto err;

    ok = 1;

err:

    OPENSSL_clear_free(oct_buf, oct_buf_len);

    if (!ok) {

        if (pt != point)

            EC_POINT_clear_free(pt);

        pt = NULL;

    }

    return pt;

}