text: /*
   *  Platform-specific and custom entropy polling functions
   *
   *  Copyright (C) 2006-2016, ARM Limited, All Rights Reserved
   *  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.
   *
   *  This file is part of mbed TLS (https://tls.mbed.org)
   */
  
  #if !defined(MBEDTLS_CONFIG_FILE)
  #include "mbedtls/config.h"
  #else
  #include MBEDTLS_CONFIG_FILE
  #endif
  
  #if defined(MBEDTLS_ENTROPY_C)
  
  #include "mbedtls/entropy.h"
  #include "mbedtls/entropy_poll.h"
  
  #if defined(MBEDTLS_TIMING_C)
  #include <string.h>
  #include "mbedtls/timing.h"
  #endif
  #if defined(MBEDTLS_HAVEGE_C)
  #include "mbedtls/havege.h"
  #endif
  #if defined(MBEDTLS_ENTROPY_NV_SEED)
  #include "mbedtls/platform.h"
  #endif
  
  #if !defined(MBEDTLS_NO_PLATFORM_ENTROPY)
  
  #if !defined(unix) && !defined(__unix__) && !defined(__unix) && \
      !defined(__APPLE__) && !defined(_WIN32)
  #error "Platform entropy sources only work on Unix and Windows, see MBEDTLS_NO_PLATFORM_ENTROPY in config.h"
  #endif
  
  #if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)
  
  #if !defined(_WIN32_WINNT)
  #define _WIN32_WINNT 0x0400
  #endif
  #include <windows.h>
  #include <wincrypt.h>
  
  int mbedtls_platform_entropy_poll( void *data, unsigned char *output, size_t len,
                                     size_t *olen )
  {
      HCRYPTPROV provider;
      ((void) data);
      *olen = 0;
  
      if ( CryptAcquireContext( &provider, NULL, NULL,
                                PROV_RSA_FULL, CRYPT_VERIFYCONTEXT ) == FALSE ) {
          return ( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
      }
  
      if ( CryptGenRandom( provider, (DWORD) len, output ) == FALSE ) {
          CryptReleaseContext( provider, 0 );
          return ( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
      }
  
      CryptReleaseContext( provider, 0 );
      *olen = len;
  
      return ( 0 );
  }
  #else /* _WIN32 && !EFIX64 && !EFI32 */
  
  /*
   * Test for Linux getrandom() support.
   * Since there is no wrapper in the libc yet, use the generic syscall wrapper
   * available in GNU libc and compatible libc's (eg uClibc).
   */
  #if defined(__linux__) && defined(__GLIBC__)
  #include <unistd.h>
  #include <sys/syscall.h>
  #if defined(SYS_getrandom)
  #define HAVE_GETRANDOM
  
  static int getrandom_wrapper( void *buf, size_t buflen, unsigned int flags )
  {
      /* MemSan cannot understand that the syscall writes to the buffer */
  #if defined(__has_feature)
  #if __has_feature(memory_sanitizer)
      memset( buf, 0, buflen );
  #endif
  #endif
  
      return ( syscall( SYS_getrandom, buf, buflen, flags ) );
  }
  
  #include <sys/utsname.h>
  /* Check if version is at least 3.17.0 */
  static int check_version_3_17_plus( void )
  {
      int minor;
      struct utsname un;
      const char *ver;
  
      /* Get version information */
      uname(&un);
      ver = un.release;
  
      /* Check major version; assume a single digit */
      if ( ver[0] < '3' || ver[0] > '9' || ver [1] != '.' )
          return ( -1 );
  
      if ( ver[0] - '0' > 3 )
          return ( 0 );
  
      /* Ok, so now we know major == 3, check minor.
       * Assume 1 or 2 digits. */
      if ( ver[2] < '0' || ver[2] > '9' )
          return ( -1 );
  
      minor = ver[2] - '0';
  
      if ( ver[3] >= '0' && ver[3] <= '9' )
          minor = 10 * minor + ver[3] - '0';
      else if ( ver [3] != '.' )
          return ( -1 );
  
      if ( minor < 17 )
          return ( -1 );
  
      return ( 0 );
  }
  static int has_getrandom = -1;
  #endif /* SYS_getrandom */
  #endif /* __linux__ */
  
  #include <stdio.h>
  
  int mbedtls_platform_entropy_poll( void *data,
                                     unsigned char *output, size_t len, size_t *olen )
  {
      FILE *file;
      size_t read_len;
      ((void) data);
  
  #if defined(HAVE_GETRANDOM)
      if ( has_getrandom == -1 )
          has_getrandom = ( check_version_3_17_plus() == 0 );
  
      if ( has_getrandom ) {
          int ret;
  
          if ( ( ret = getrandom_wrapper( output, len, 0 ) ) < 0 )
              return ( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
  
          *olen = ret;
          return ( 0 );
      }
  #endif /* HAVE_GETRANDOM */
  
      *olen = 0;
  
      file = fopen( "/dev/urandom", "rb" );
      if ( file == NULL )
          return ( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
  
      read_len = fread( output, 1, len, file );
      if ( read_len != len ) {
          fclose( file );
          return ( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
      }
  
      fclose( file );
      *olen = len;
  
      return ( 0 );
  }
  #endif /* _WIN32 && !EFIX64 && !EFI32 */
  #endif /* !MBEDTLS_NO_PLATFORM_ENTROPY */
  
  #if defined(MBEDTLS_TEST_NULL_ENTROPY)
  int mbedtls_null_entropy_poll( void *data,
                                 unsigned char *output, size_t len, size_t *olen )
  {
      ((void) data);
      ((void) output);
      *olen = 0;
  
      if ( len < sizeof(unsigned char) )
          return ( 0 );
  
      *olen = sizeof(unsigned char);
  
      return ( 0 );
  }
  #endif
  
  #if defined(MBEDTLS_TIMING_C)
  int mbedtls_hardclock_poll( void *data,
                              unsigned char *output, size_t len, size_t *olen )
  {
      unsigned long timer = mbedtls_timing_hardclock();
      ((void) data);
      *olen = 0;
  
      if ( len < sizeof(unsigned long) )
          return ( 0 );
  
      memcpy( output, &timer, sizeof(unsigned long) );
      *olen = sizeof(unsigned long);
  
      return ( 0 );
  }
  #endif /* MBEDTLS_TIMING_C */
  
  #if defined(MBEDTLS_HAVEGE_C)
  int mbedtls_havege_poll( void *data,
                           unsigned char *output, size_t len, size_t *olen )
  {
      mbedtls_havege_state *hs = (mbedtls_havege_state *) data;
      *olen = 0;
  
      if ( mbedtls_havege_random( hs, output, len ) != 0 )
          return ( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
  
      *olen = len;
  
      return ( 0 );
  }
  #endif /* MBEDTLS_HAVEGE_C */
  
  #if defined(MBEDTLS_ENTROPY_NV_SEED)
  int mbedtls_nv_seed_poll( void *data,
                            unsigned char *output, size_t len, size_t *olen )
  {
      unsigned char buf[MBEDTLS_ENTROPY_BLOCK_SIZE];
      size_t use_len = MBEDTLS_ENTROPY_BLOCK_SIZE;
      ((void) data);
  
      memset( buf, 0, MBEDTLS_ENTROPY_BLOCK_SIZE );
  
      if ( mbedtls_nv_seed_read( buf, MBEDTLS_ENTROPY_BLOCK_SIZE ) < 0 )
          return ( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
  
      if ( len < use_len )
          use_len = len;
  
      memcpy( output, buf, use_len );
      *olen = use_len;
  
      return ( 0 );
  }
  #endif /* MBEDTLS_ENTROPY_NV_SEED */
  
  #endif /* MBEDTLS_ENTROPY_C */
  