276 lines
7.3 KiB
C
276 lines
7.3 KiB
C
/*
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* Platform-specific and custom entropy polling functions
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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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* This file is provided under the Apache License 2.0, or the
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* GNU General Public License v2.0 or later.
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*
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* **********
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* Apache License 2.0:
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* **********
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*
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* **********
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* GNU General Public License v2.0 or later:
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* **********
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*/
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#if defined(__linux__)
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/* Ensure that syscall() is available even when compiling with -std=c99 */
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#define _GNU_SOURCE
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#endif
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#if !defined(MBEDTLS_CONFIG_FILE)
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#include "mbedtls/config.h"
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#else
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#include MBEDTLS_CONFIG_FILE
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#endif
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#include <string.h>
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#if defined(MBEDTLS_ENTROPY_C)
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#include "mbedtls/entropy.h"
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#include "mbedtls/entropy_poll.h"
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#if defined(MBEDTLS_TIMING_C)
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#include "mbedtls/timing.h"
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#endif
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#if defined(MBEDTLS_HAVEGE_C)
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#include "mbedtls/havege.h"
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#endif
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#if defined(MBEDTLS_ENTROPY_NV_SEED)
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#include "mbedtls/platform.h"
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#endif
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#if !defined(MBEDTLS_NO_PLATFORM_ENTROPY)
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#if !defined(unix) && !defined(__unix__) && !defined(__unix) && \
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!defined(__APPLE__) && !defined(_WIN32) && !defined(__QNXNTO__) && \
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!defined(__HAIKU__)
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#error "Platform entropy sources only work on Unix and Windows, see MBEDTLS_NO_PLATFORM_ENTROPY in config.h"
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#endif
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#if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)
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#if !defined(_WIN32_WINNT)
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#define _WIN32_WINNT 0x0400
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#endif
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#include <windows.h>
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#include <bcrypt.h>
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#if defined(_MSC_VER) && _MSC_VER <= 1600
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/* Visual Studio 2010 and earlier issue a warning when both <stdint.h> and
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* <intsafe.h> are included, as they redefine a number of <TYPE>_MAX constants.
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* These constants are guaranteed to be the same, though, so we suppress the
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* warning when including intsafe.h.
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*/
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#pragma warning( push )
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#pragma warning( disable : 4005 )
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#endif
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#include <intsafe.h>
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#if defined(_MSC_VER) && _MSC_VER <= 1600
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#pragma warning( pop )
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#endif
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int mbedtls_platform_entropy_poll( void *data, unsigned char *output, size_t len,
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size_t *olen )
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{
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ULONG len_as_ulong = 0;
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((void) data);
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*olen = 0;
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/*
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* BCryptGenRandom takes ULONG for size, which is smaller than size_t on
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* 64-bit Windows platforms. Ensure len's value can be safely converted into
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* a ULONG.
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*/
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if ( FAILED( SizeTToULong( len, &len_as_ulong ) ) )
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{
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return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
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}
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if ( !BCRYPT_SUCCESS( BCryptGenRandom( NULL, output, len_as_ulong, BCRYPT_USE_SYSTEM_PREFERRED_RNG ) ) )
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{
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return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
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}
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*olen = len;
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return( 0 );
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}
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#else /* _WIN32 && !EFIX64 && !EFI32 */
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/*
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* Test for Linux getrandom() support.
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* Since there is no wrapper in the libc yet, use the generic syscall wrapper
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* available in GNU libc and compatible libc's (eg uClibc).
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*/
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#if defined(__linux__) && defined(__GLIBC__)
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#include <unistd.h>
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#include <sys/syscall.h>
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#if defined(SYS_getrandom)
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#define HAVE_GETRANDOM
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#include <errno.h>
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static int getrandom_wrapper( void *buf, size_t buflen, unsigned int flags )
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{
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/* MemSan cannot understand that the syscall writes to the buffer */
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#if defined(__has_feature)
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#if __has_feature(memory_sanitizer)
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memset( buf, 0, buflen );
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#endif
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#endif
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return( syscall( SYS_getrandom, buf, buflen, flags ) );
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}
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#endif /* SYS_getrandom */
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#endif /* __linux__ */
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#include <stdio.h>
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int mbedtls_platform_entropy_poll( void *data,
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unsigned char *output, size_t len, size_t *olen )
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{
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FILE *file;
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size_t read_len;
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int ret;
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((void) data);
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#if defined(HAVE_GETRANDOM)
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ret = getrandom_wrapper( output, len, 0 );
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if( ret >= 0 )
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{
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*olen = ret;
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return( 0 );
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}
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else if( errno != ENOSYS )
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return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
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/* Fall through if the system call isn't known. */
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#else
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((void) ret);
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#endif /* HAVE_GETRANDOM */
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*olen = 0;
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file = fopen( "/dev/urandom", "rb" );
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if( file == NULL )
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return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
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read_len = fread( output, 1, len, file );
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if( read_len != len )
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{
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fclose( file );
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return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
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}
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fclose( file );
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*olen = len;
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return( 0 );
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}
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#endif /* _WIN32 && !EFIX64 && !EFI32 */
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#endif /* !MBEDTLS_NO_PLATFORM_ENTROPY */
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#if defined(MBEDTLS_TEST_NULL_ENTROPY)
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int mbedtls_null_entropy_poll( void *data,
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unsigned char *output, size_t len, size_t *olen )
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{
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((void) data);
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((void) output);
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*olen = 0;
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if( len < sizeof(unsigned char) )
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return( 0 );
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*olen = sizeof(unsigned char);
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return( 0 );
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}
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#endif
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#if defined(MBEDTLS_TIMING_C)
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int mbedtls_hardclock_poll( void *data,
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unsigned char *output, size_t len, size_t *olen )
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{
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unsigned long timer = mbedtls_timing_hardclock();
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((void) data);
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*olen = 0;
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if( len < sizeof(unsigned long) )
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return( 0 );
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memcpy( output, &timer, sizeof(unsigned long) );
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*olen = sizeof(unsigned long);
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return( 0 );
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}
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#endif /* MBEDTLS_TIMING_C */
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#if defined(MBEDTLS_HAVEGE_C)
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int mbedtls_havege_poll( void *data,
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unsigned char *output, size_t len, size_t *olen )
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{
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mbedtls_havege_state *hs = (mbedtls_havege_state *) data;
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*olen = 0;
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if( mbedtls_havege_random( hs, output, len ) != 0 )
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return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
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*olen = len;
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return( 0 );
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}
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#endif /* MBEDTLS_HAVEGE_C */
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#if defined(MBEDTLS_ENTROPY_NV_SEED)
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int mbedtls_nv_seed_poll( void *data,
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unsigned char *output, size_t len, size_t *olen )
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{
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unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];
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size_t use_len = MBEDTLS_ENTROPY_BLOCK_SIZE;
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((void) data);
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memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE );
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if( mbedtls_nv_seed_read( buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) < 0 )
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return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
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if( len < use_len )
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use_len = len;
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memcpy( output, buf, use_len );
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*olen = use_len;
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return( 0 );
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}
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#endif /* MBEDTLS_ENTROPY_NV_SEED */
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#endif /* MBEDTLS_ENTROPY_C */
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