library/timing.c

/*
 *  Portable interface to the CPU cycle counter
 *
 *  Copyright The Mbed TLS Contributors
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

#include "common.h"

#if defined(MBEDTLS_TIMING_C)

#include "mbedtls/timing.h"

#if !defined(MBEDTLS_TIMING_ALT)

#if !defined(unix) && !defined(__unix__) && !defined(__unix) && \
    !defined(__APPLE__) && !defined(_WIN32) && !defined(__QNXNTO__) && \
    !defined(__HAIKU__) && !defined(__midipix__)
#error "This module only works on Unix and Windows, see MBEDTLS_TIMING_C in mbedtls_config.h"
#endif

#if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)

#include <windows.h>
#include <process.h>

struct _hr_time
{
    LARGE_INTEGER start;
};

#else

#include <unistd.h>
#include <sys/types.h>
#include <signal.h>
/* time.h should be included independently of MBEDTLS_HAVE_TIME. If the
 * platform matches the ifdefs above, it will be used. */
#include <time.h>
#include <sys/time.h>
struct _hr_time
{
    struct timeval start;
};
#endif /* _WIN32 && !EFIX64 && !EFI32 */

/**
 * \brief          Return the elapsed time in milliseconds
 *
 * \warning        May change without notice
 *
 * \param val      points to a timer structure
 * \param reset    If 0, query the elapsed time. Otherwise (re)start the timer.
 *
 * \return         Elapsed time since the previous reset in ms. When
 *                 restarting, this is always 0.
 *
 * \note           To initialize a timer, call this function with reset=1.
 *
 *                 Determining the elapsed time and resetting the timer is not
 *                 atomic on all platforms, so after the sequence
 *                 `{ get_timer(1); ...; time1 = get_timer(1); ...; time2 =
 *                 get_timer(0) }` the value time1+time2 is only approximately
 *                 the delay since the first reset.
 */
#if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)

unsigned long mbedtls_timing_get_timer( struct mbedtls_timing_hr_time *val, int reset )
{
    struct _hr_time *t = (struct _hr_time *) val;

    if( reset )
    {
        QueryPerformanceCounter( &t->start );
        return( 0 );
    }
    else
    {
        unsigned long delta;
        LARGE_INTEGER now, hfreq;
        QueryPerformanceCounter(  &now );
        QueryPerformanceFrequency( &hfreq );
        delta = (unsigned long)( ( now.QuadPart - t->start.QuadPart ) * 1000ul
                                 / hfreq.QuadPart );
        return( delta );
    }
}

#else /* _WIN32 && !EFIX64 && !EFI32 */

unsigned long mbedtls_timing_get_timer( struct mbedtls_timing_hr_time *val, int reset )
{
    struct _hr_time *t = (struct _hr_time *) val;

    if( reset )
    {
        gettimeofday( &t->start, NULL );
        return( 0 );
    }
    else
    {
        unsigned long delta;
        struct timeval now;
        gettimeofday( &now, NULL );
        delta = ( now.tv_sec  - t->start.tv_sec  ) * 1000ul
              + ( now.tv_usec - t->start.tv_usec ) / 1000;
        return( delta );
    }
}

#endif /* _WIN32 && !EFIX64 && !EFI32 */

/*
 * Set delays to watch
 */
void mbedtls_timing_set_delay( void *data, uint32_t int_ms, uint32_t fin_ms )
{
    mbedtls_timing_delay_context *ctx = (mbedtls_timing_delay_context *) data;

    ctx->int_ms = int_ms;
    ctx->fin_ms = fin_ms;

    if( fin_ms != 0 )
        (void) mbedtls_timing_get_timer( &ctx->timer, 1 );
}

/*
 * Get number of delays expired
 */
int mbedtls_timing_get_delay( void *data )
{
    mbedtls_timing_delay_context *ctx = (mbedtls_timing_delay_context *) data;
    unsigned long elapsed_ms;

    if( ctx->fin_ms == 0 )
        return( -1 );

    elapsed_ms = mbedtls_timing_get_timer( &ctx->timer, 0 );

    if( elapsed_ms >= ctx->fin_ms )
        return( 2 );

    if( elapsed_ms >= ctx->int_ms )
        return( 1 );

    return( 0 );
}

/*
 * Get the final delay.
 */
uint32_t mbedtls_timing_get_final_delay(
                                      const mbedtls_timing_delay_context *data )
{
    return( data->fin_ms );
}
#endif /* !MBEDTLS_TIMING_ALT */
#endif /* MBEDTLS_TIMING_C */