263 lines
8.6 KiB
C
263 lines
8.6 KiB
C
/*
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* Common and shared functions used by multiple modules in the Mbed TLS
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* library.
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*
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
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*/
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/*
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* Ensure gmtime_r is available even with -std=c99; must be defined before
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* mbedtls_config.h, which pulls in glibc's features.h. Harmless on other platforms
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* except OpenBSD, where it stops us accessing explicit_bzero.
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*/
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#if !defined(_POSIX_C_SOURCE) && !defined(__OpenBSD__)
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#define _POSIX_C_SOURCE 200112L
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#endif
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#if !defined(_GNU_SOURCE)
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/* Clang requires this to get support for explicit_bzero */
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#define _GNU_SOURCE
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#endif
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#include "common.h"
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#include "mbedtls/platform_util.h"
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#include "mbedtls/platform.h"
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#include "mbedtls/threading.h"
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#include <stddef.h>
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#ifndef __STDC_WANT_LIB_EXT1__
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#define __STDC_WANT_LIB_EXT1__ 1 /* Ask for the C11 gmtime_s() and memset_s() if available */
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#endif
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#include <string.h>
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#if defined(_WIN32)
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#include <windows.h>
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#endif
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// Detect platforms known to support explicit_bzero()
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#if defined(__GLIBC__) && (__GLIBC__ >= 2) && (__GLIBC_MINOR__ >= 25)
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#define MBEDTLS_PLATFORM_HAS_EXPLICIT_BZERO 1
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#elif (defined(__FreeBSD__) && (__FreeBSD_version >= 1100037)) || defined(__OpenBSD__)
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#define MBEDTLS_PLATFORM_HAS_EXPLICIT_BZERO 1
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#endif
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#if !defined(MBEDTLS_PLATFORM_ZEROIZE_ALT)
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#undef HAVE_MEMORY_SANITIZER
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#if defined(__has_feature)
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#if __has_feature(memory_sanitizer)
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#include <sanitizer/msan_interface.h>
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#define HAVE_MEMORY_SANITIZER
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#endif
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#endif
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/*
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* Where possible, we try to detect the presence of a platform-provided
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* secure memset, such as explicit_bzero(), that is safe against being optimized
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* out, and use that.
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*
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* For other platforms, we provide an implementation that aims not to be
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* optimized out by the compiler.
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*
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* This implementation for mbedtls_platform_zeroize() was inspired from Colin
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* Percival's blog article at:
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*
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* http://www.daemonology.net/blog/2014-09-04-how-to-zero-a-buffer.html
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*
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* It uses a volatile function pointer to the standard memset(). Because the
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* pointer is volatile the compiler expects it to change at
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* any time and will not optimize out the call that could potentially perform
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* other operations on the input buffer instead of just setting it to 0.
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* Nevertheless, as pointed out by davidtgoldblatt on Hacker News
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* (refer to http://www.daemonology.net/blog/2014-09-05-erratum.html for
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* details), optimizations of the following form are still possible:
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*
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* if (memset_func != memset)
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* memset_func(buf, 0, len);
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*
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* Note that it is extremely difficult to guarantee that
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* the memset() call will not be optimized out by aggressive compilers
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* in a portable way. For this reason, Mbed TLS also provides the configuration
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* option MBEDTLS_PLATFORM_ZEROIZE_ALT, which allows users to configure
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* mbedtls_platform_zeroize() to use a suitable implementation for their
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* platform and needs.
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*/
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#if !defined(MBEDTLS_PLATFORM_HAS_EXPLICIT_BZERO) && !(defined(__STDC_LIB_EXT1__) && \
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!defined(__IAR_SYSTEMS_ICC__)) \
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&& !defined(_WIN32)
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static void *(*const volatile memset_func)(void *, int, size_t) = memset;
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#endif
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void mbedtls_platform_zeroize(void *buf, size_t len)
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{
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if (len > 0) {
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#if defined(MBEDTLS_PLATFORM_HAS_EXPLICIT_BZERO)
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explicit_bzero(buf, len);
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#if defined(HAVE_MEMORY_SANITIZER)
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/* You'd think that Msan would recognize explicit_bzero() as
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* equivalent to bzero(), but it actually doesn't on several
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* platforms, including Linux (Ubuntu 20.04).
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* https://github.com/google/sanitizers/issues/1507
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* https://github.com/openssh/openssh-portable/commit/74433a19bb6f4cef607680fa4d1d7d81ca3826aa
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*/
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__msan_unpoison(buf, len);
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#endif
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#elif defined(__STDC_LIB_EXT1__) && !defined(__IAR_SYSTEMS_ICC__)
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memset_s(buf, len, 0, len);
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#elif defined(_WIN32)
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SecureZeroMemory(buf, len);
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#else
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memset_func(buf, 0, len);
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#endif
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#if defined(__GNUC__)
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/* For clang and recent gcc, pretend that we have some assembly that reads the
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* zero'd memory as an additional protection against being optimised away. */
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#if defined(__clang__) || (__GNUC__ >= 10)
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#if defined(__clang__)
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#pragma clang diagnostic push
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#pragma clang diagnostic ignored "-Wvla"
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#elif defined(MBEDTLS_COMPILER_IS_GCC)
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#pragma GCC diagnostic push
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#pragma GCC diagnostic ignored "-Wvla"
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#endif
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asm volatile ("" : : "m" (*(char (*)[len]) buf) :);
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#if defined(__clang__)
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#pragma clang diagnostic pop
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#elif defined(MBEDTLS_COMPILER_IS_GCC)
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#pragma GCC diagnostic pop
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#endif
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#endif
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#endif
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}
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}
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#endif /* MBEDTLS_PLATFORM_ZEROIZE_ALT */
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void mbedtls_zeroize_and_free(void *buf, size_t len)
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{
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if (buf != NULL) {
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mbedtls_platform_zeroize(buf, len);
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}
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mbedtls_free(buf);
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}
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#if defined(MBEDTLS_HAVE_TIME_DATE) && !defined(MBEDTLS_PLATFORM_GMTIME_R_ALT)
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#include <time.h>
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#if !defined(_WIN32) && (defined(unix) || \
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defined(__unix) || defined(__unix__) || (defined(__APPLE__) && \
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defined(__MACH__)) || defined__midipix__)
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#include <unistd.h>
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#endif /* !_WIN32 && (unix || __unix || __unix__ ||
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* (__APPLE__ && __MACH__) || __midipix__) */
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#if !((defined(_POSIX_VERSION) && _POSIX_VERSION >= 200809L) || \
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(defined(_POSIX_THREAD_SAFE_FUNCTIONS) && \
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_POSIX_THREAD_SAFE_FUNCTIONS >= 200112L))
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/*
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* This is a convenience shorthand macro to avoid checking the long
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* preprocessor conditions above. Ideally, we could expose this macro in
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* platform_util.h and simply use it in platform_util.c, threading.c and
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* threading.h. However, this macro is not part of the Mbed TLS public API, so
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* we keep it private by only defining it in this file
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*/
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#if !(defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)) || \
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(defined(__MINGW32__) && !defined(__MINGW64_VERSION_MAJOR))
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#define PLATFORM_UTIL_USE_GMTIME
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#endif
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#endif /* !( ( defined(_POSIX_VERSION) && _POSIX_VERSION >= 200809L ) || \
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( defined(_POSIX_THREAD_SAFE_FUNCTIONS ) && \
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_POSIX_THREAD_SAFE_FUNCTIONS >= 200112L ) ) */
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struct tm *mbedtls_platform_gmtime_r(const mbedtls_time_t *tt,
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struct tm *tm_buf)
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{
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#if defined(_WIN32) && !defined(PLATFORM_UTIL_USE_GMTIME)
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#if defined(__STDC_LIB_EXT1__)
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return (gmtime_s(tt, tm_buf) == 0) ? NULL : tm_buf;
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#else
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/* MSVC and mingw64 argument order and return value are inconsistent with the C11 standard */
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return (gmtime_s(tm_buf, tt) == 0) ? tm_buf : NULL;
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#endif
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#elif !defined(PLATFORM_UTIL_USE_GMTIME)
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return gmtime_r(tt, tm_buf);
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#else
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struct tm *lt;
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#if defined(MBEDTLS_THREADING_C)
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if (mbedtls_mutex_lock(&mbedtls_threading_gmtime_mutex) != 0) {
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return NULL;
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}
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#endif /* MBEDTLS_THREADING_C */
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lt = gmtime(tt);
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if (lt != NULL) {
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memcpy(tm_buf, lt, sizeof(struct tm));
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}
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#if defined(MBEDTLS_THREADING_C)
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if (mbedtls_mutex_unlock(&mbedtls_threading_gmtime_mutex) != 0) {
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return NULL;
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}
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#endif /* MBEDTLS_THREADING_C */
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return (lt == NULL) ? NULL : tm_buf;
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#endif /* _WIN32 && !EFIX64 && !EFI32 */
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}
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#endif /* MBEDTLS_HAVE_TIME_DATE && MBEDTLS_PLATFORM_GMTIME_R_ALT */
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#if defined(MBEDTLS_TEST_HOOKS)
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void (*mbedtls_test_hook_test_fail)(const char *, int, const char *);
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#endif /* MBEDTLS_TEST_HOOKS */
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#if defined(MBEDTLS_HAVE_TIME) && !defined(MBEDTLS_PLATFORM_MS_TIME_ALT)
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#include <time.h>
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#if !defined(_WIN32) && \
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(defined(unix) || defined(__unix) || defined(__unix__) || \
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(defined(__APPLE__) && defined(__MACH__)) || defined(__HAIKU__) || defined(__midipix__))
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#include <unistd.h>
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#endif \
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/* !_WIN32 && (unix || __unix || __unix__ || (__APPLE__ && __MACH__) || __HAIKU__ || __midipix__) */
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#if (defined(_POSIX_VERSION) && _POSIX_VERSION >= 199309L) || defined(__HAIKU__)
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mbedtls_ms_time_t mbedtls_ms_time(void)
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{
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int ret;
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struct timespec tv;
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mbedtls_ms_time_t current_ms;
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#if defined(__linux__) && defined(CLOCK_BOOTTIME) || defined(__midipix__)
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ret = clock_gettime(CLOCK_BOOTTIME, &tv);
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#else
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ret = clock_gettime(CLOCK_MONOTONIC, &tv);
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#endif
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if (ret) {
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return time(NULL) * 1000;
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}
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current_ms = tv.tv_sec;
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return current_ms*1000 + tv.tv_nsec / 1000000;
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}
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#elif defined(_WIN32) || defined(WIN32) || defined(__CYGWIN__) || \
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defined(__MINGW32__) || defined(_WIN64)
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#include <windows.h>
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mbedtls_ms_time_t mbedtls_ms_time(void)
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{
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FILETIME ct;
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mbedtls_ms_time_t current_ms;
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GetSystemTimeAsFileTime(&ct);
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current_ms = ((mbedtls_ms_time_t) ct.dwLowDateTime +
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((mbedtls_ms_time_t) (ct.dwHighDateTime) << 32LL))/10000;
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return current_ms;
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}
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#else
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#error "No mbedtls_ms_time available"
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#endif
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#endif /* MBEDTLS_HAVE_TIME && !MBEDTLS_PLATFORM_MS_TIME_ALT */
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