283 lines
7 KiB
C
283 lines
7 KiB
C
/*
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* Platform-specific and custom entropy polling functions
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*
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* Copyright (C) 2006-2016, ARM Limited, All Rights Reserved
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* SPDX-License-Identifier: Apache-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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* This file is part of mbed TLS (https://tls.mbed.org)
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*/
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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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#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 <string.h>
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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)
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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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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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#include <sys/utsname.h>
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/* Check if version is at least 3.17.0 */
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static int check_version_3_17_plus( void )
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{
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int minor;
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struct utsname un;
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const char *ver;
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/* Get version information */
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uname(&un);
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ver = un.release;
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/* Check major version; assume a single digit */
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if( ver[0] < '3' || ver[0] > '9' || ver [1] != '.' )
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return( -1 );
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if( ver[0] - '0' > 3 )
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return( 0 );
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/* Ok, so now we know major == 3, check minor.
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* Assume 1 or 2 digits. */
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if( ver[2] < '0' || ver[2] > '9' )
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return( -1 );
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minor = ver[2] - '0';
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if( ver[3] >= '0' && ver[3] <= '9' )
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minor = 10 * minor + ver[3] - '0';
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else if( ver [3] != '.' )
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return( -1 );
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if( minor < 17 )
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return( -1 );
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return( 0 );
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}
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static int has_getrandom = -1;
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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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((void) data);
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#if defined(HAVE_GETRANDOM)
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if( has_getrandom == -1 )
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has_getrandom = ( check_version_3_17_plus() == 0 );
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if( has_getrandom )
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{
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int ret;
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if( ( ret = getrandom_wrapper( output, len, 0 ) ) < 0 )
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return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
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*olen = ret;
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return( 0 );
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}
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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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