/* -*-c-*-
 *  Error message information
 *
 *  Copyright The Mbed TLS Contributors
 *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
 */

#include "mbedtls_common.h"

#include "mbedtls/error.h"

#if defined(MBEDTLS_ERROR_C) || defined(MBEDTLS_ERROR_STRERROR_DUMMY)

#if defined(MBEDTLS_ERROR_C)

#include "mbedtls/platform.h"

#include <stdio.h>
#include <string.h>

HEADER_INCLUDED

static const char *mbedtls_high_level_strerr(int error_code)
{
    int high_level_error_code;

    if (error_code < 0) {
        error_code = -error_code;
    }

    /* Extract the high-level part from the error code. */
    high_level_error_code = error_code & 0xFF80;

    switch (high_level_error_code) {
    /* Begin Auto-Generated Code. */
    HIGH_LEVEL_CODE_CHECKS
        /* End Auto-Generated Code. */

        default:
            break;
    }

    return NULL;
}

static const char *mbedtls_low_level_strerr(int error_code)
{
    int low_level_error_code;

    if (error_code < 0) {
        error_code = -error_code;
    }

    /* Extract the low-level part from the error code. */
    low_level_error_code = error_code & ~0xFF80;

    switch (low_level_error_code) {
    /* Begin Auto-Generated Code. */
    LOW_LEVEL_CODE_CHECKS
        /* End Auto-Generated Code. */

        default:
            break;
    }

    return NULL;
}

void mbedtls_strerror(int ret, char *buf, size_t buflen)
{
    size_t len;
    int use_ret;
    const char *high_level_error_description = NULL;
    const char *low_level_error_description = NULL;

    if (buflen == 0) {
        return;
    }

    memset(buf, 0x00, buflen);

    if (ret < 0) {
        ret = -ret;
    }

    if (ret & 0xFF80) {
        use_ret = ret & 0xFF80;

        // Translate high level error code.
        high_level_error_description = mbedtls_high_level_strerr(ret);

        if (high_level_error_description == NULL) {
            mbedtls_snprintf(buf, buflen, "UNKNOWN ERROR CODE (%04X)", (unsigned int) use_ret);
        } else {
            mbedtls_snprintf(buf, buflen, "%s", high_level_error_description);
        }

#if defined(MBEDTLS_SSL_TLS_C)
        // Early return in case of a fatal error - do not try to translate low
        // level code.
        if (use_ret == -(MBEDTLS_ERR_SSL_FATAL_ALERT_MESSAGE)) {
            return;
        }
#endif /* MBEDTLS_SSL_TLS_C */
    }

    use_ret = ret & ~0xFF80;

    if (use_ret == 0) {
        return;
    }

    // If high level code is present, make a concatenation between both
    // error strings.
    //
    len = strlen(buf);

    if (len > 0) {
        if (buflen - len < 5) {
            return;
        }

        mbedtls_snprintf(buf + len, buflen - len, " : ");

        buf += len + 3;
        buflen -= len + 3;
    }

    // Translate low level error code.
    low_level_error_description = mbedtls_low_level_strerr(ret);

    if (low_level_error_description == NULL) {
        mbedtls_snprintf(buf, buflen, "UNKNOWN ERROR CODE (%04X)", (unsigned int) use_ret);
    } else {
        mbedtls_snprintf(buf, buflen, "%s", low_level_error_description);
    }
}

#else /* MBEDTLS_ERROR_C */

/*
 * Provide a dummy implementation when MBEDTLS_ERROR_C is not defined
 */
void mbedtls_strerror(int ret, char *buf, size_t buflen)
{
    ((void) ret);

    if (buflen > 0) {
        buf[0] = '\0';
    }
}

#endif /* MBEDTLS_ERROR_C */

#endif /* MBEDTLS_ERROR_C || MBEDTLS_ERROR_STRERROR_DUMMY */
