/*

   +----------------------------------------------------------------------+

   | Copyright (c) The PHP Group                                          |

   +----------------------------------------------------------------------+

   | This source file is subject to version 3.01 of the PHP license,      |

   | that is bundled with this package in the file LICENSE, and is        |

   | available through the world-wide-web at the following url:           |

   | https://www.php.net/license/3_01.txt                                 |

   | If you did not receive a copy of the PHP license and are unable to   |

   | obtain it through the world-wide-web, please send a note to          |

   | license@php.net so we can mail you a copy immediately.               |

   +----------------------------------------------------------------------+

   | Authors: Sammy Kaye Powers <me@sammyk.me>                            |

   +----------------------------------------------------------------------+

*/

#include <stdlib.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <math.h>

#include "php.h"

#include "zend_exceptions.h"

#include "php_random.h"

#ifdef PHP_WIN32

# include "win32/winutil.h"

#endif

#ifdef __linux__

# include <sys/syscall.h>

#endif

#if HAVE_SYS_PARAM_H

# include <sys/param.h>

# if (__FreeBSD__ && __FreeBSD_version > 1200000) || (__DragonFly__ && __DragonFly_version >= 500700) || defined(__sun)

#  include <sys/random.h>

# endif

#endif

#if HAVE_COMMONCRYPTO_COMMONRANDOM_H

# include <CommonCrypto/CommonCryptoError.h>

# include <CommonCrypto/CommonRandom.h>

#endif

#if __has_feature(memory_sanitizer)

# include <sanitizer/msan_interface.h>

#endif

#ifdef ZTS

int random_globals_id;

#else

php_random_globals random_globals;

#endif

static void random_globals_ctor(php_random_globals *random_globals_p)

{

  random_globals_p->fd = -1;

}

static void random_globals_dtor(php_random_globals *random_globals_p)

{

  if (random_globals_p->fd > 0) {

    close(random_globals_p->fd);

    random_globals_p->fd = -1;

  }

}

/* {{{ */

PHP_MINIT_FUNCTION(random)

{

#ifdef ZTS

  ts_allocate_id(&random_globals_id, sizeof(php_random_globals), (ts_allocate_ctor)random_globals_ctor, (ts_allocate_dtor)random_globals_dtor);

#else

  random_globals_ctor(&random_globals);

#endif

  return SUCCESS;

}

/* }}} */

/* {{{ */

PHP_MSHUTDOWN_FUNCTION(random)

{

#ifndef ZTS

  random_globals_dtor(&random_globals);

#endif

  return SUCCESS;

}

/* }}} */

/* {{{ php_random_bytes */

PHPAPI int php_random_bytes(void *bytes, size_t size, bool should_throw)

{

#ifdef PHP_WIN32

  /* Defer to CryptGenRandom on Windows */

  if (php_win32_get_random_bytes(bytes, size) == FAILURE) {

    if (should_throw) {

      zend_throw_exception(zend_ce_exception, "Could not gather sufficient random data", 0);

    }

    return FAILURE;

  }

#elif HAVE_COMMONCRYPTO_COMMONRANDOM_H

  /*

   * Purposely prioritized upon arc4random_buf for modern macOs releases

   * arc4random api on this platform uses `ccrng_generate` which returns

   * a status but silented to respect the "no fail" arc4random api interface

   * the vast majority of the time, it works fine ; but better make sure we catch failures

   */

  if (CCRandomGenerateBytes(bytes, size) != kCCSuccess) {

    if (should_throw) {

      zend_throw_exception(zend_ce_exception, "Error generating bytes", 0);

    }

    return FAILURE;

  }

#elif HAVE_DECL_ARC4RANDOM_BUF && ((defined(__OpenBSD__) && OpenBSD >= 201405) || (defined(__NetBSD__) && __NetBSD_Version__ >= 700000001) || defined(__APPLE__) || defined(__GLIBC__))

  arc4random_buf(bytes, size);

#else

  size_t read_bytes = 0;

  ssize_t n;

#if (defined(__linux__) && defined(SYS_getrandom)) || (defined(__FreeBSD__) && __FreeBSD_version >= 1200000) || (defined(__DragonFly__) && __DragonFly_version >= 500700) || defined(__sun)

  /* Linux getrandom(2) syscall or FreeBSD/DragonFlyBSD getrandom(2) function*/

  /* Keep reading until we get enough entropy */

  while (read_bytes < size) {

    /* Below, (bytes + read_bytes)  is pointer arithmetic.

       bytes   read_bytes  size

         |      |           |

        [#######=============] (we're going to write over the = region)

                 \\\\\\\\\\\\\

                  amount_to_read

    */

    size_t amount_to_read = size - read_bytes;

#if defined(__linux__)

    n = syscall(SYS_getrandom, bytes + read_bytes, amount_to_read, 0);

#else

    n = getrandom(bytes + read_bytes, amount_to_read, 0);

#endif

    if (n == -1) {

      if (errno == ENOSYS) {

        /* This can happen if PHP was compiled against a newer kernel where getrandom()

         * is available, but then runs on an older kernel without getrandom(). If this

         * happens we simply fall back to reading from /dev/urandom. */

        ZEND_ASSERT(read_bytes == 0);

        break;

      } else if (errno == EINTR || errno == EAGAIN) {

        /* Try again */

        continue;

      } else {

          /* If the syscall fails, fall back to reading from /dev/urandom */

        break;

      }

    }

#if __has_feature(memory_sanitizer)

    /* MSan does not instrument manual syscall invocations. */

    __msan_unpoison(bytes + read_bytes, n);

#endif

    read_bytes += (size_t) n;

  }

#endif

  if (read_bytes < size) {

    int    fd = RANDOM_G(fd);

    struct stat st;

    if (fd < 0) {

#ifdef HAVE_DEV_URANDOM

      fd = open("/dev/urandom", O_RDONLY);

#endif

      if (fd < 0) {

        if (should_throw) {

          zend_throw_exception(zend_ce_exception, "Cannot open source device", 0);

        }

        return FAILURE;

      }

      /* Does the file exist and is it a character device? */

      if (fstat(fd, &st) != 0 ||

# ifdef S_ISNAM

          !(S_ISNAM(st.st_mode) || S_ISCHR(st.st_mode))

# else

          !S_ISCHR(st.st_mode)

# endif

      ) {

        close(fd);

        if (should_throw) {

          zend_throw_exception(zend_ce_exception, "Error reading from source device", 0);

        }

        return FAILURE;

      }

      RANDOM_G(fd) = fd;

    }

    for (read_bytes = 0; read_bytes < size; read_bytes += (size_t) n) {

      n = read(fd, bytes + read_bytes, size - read_bytes);

      if (n <= 0) {

        break;

      }

    }

    if (read_bytes < size) {

      if (should_throw) {

        zend_throw_exception(zend_ce_exception, "Could not gather sufficient random data", 0);

      }

      return FAILURE;

    }

  }

#endif

  return SUCCESS;

}

/* }}} */

/* {{{ Return an arbitrary length of pseudo-random bytes as binary string */

PHP_FUNCTION(random_bytes)

{

  zend_long size;

  zend_string *bytes;

  ZEND_PARSE_PARAMETERS_START(1, 1)

    Z_PARAM_LONG(size)

  ZEND_PARSE_PARAMETERS_END();

  if (size < 1) {

    zend_argument_value_error(1, "must be greater than 0");

    RETURN_THROWS();

  }

  bytes = zend_string_alloc(size, 0);

  if (php_random_bytes_throw(ZSTR_VAL(bytes), size) == FAILURE) {

    zend_string_release_ex(bytes, 0);

    RETURN_THROWS();

  }

  ZSTR_VAL(bytes)[size] = '\0';

  RETURN_STR(bytes);

}

/* }}} */

/* {{{ */

PHPAPI int php_random_int(zend_long min, zend_long max, zend_long *result, bool should_throw)

{

  zend_ulong umax;

  zend_ulong trial;

  if (min == max) {

    *result = min;

    return SUCCESS;

  }

  umax = (zend_ulong) max - (zend_ulong) min;

  if (php_random_bytes(&trial, sizeof(trial), should_throw) == FAILURE) {

    return FAILURE;

  }

  /* Special case where no modulus is required */

  if (umax == ZEND_ULONG_MAX) {

    *result = (zend_long)trial;

    return SUCCESS;

  }

  /* Increment the max so the range is inclusive of max */

  umax++;

  /* Powers of two are not biased */

  if ((umax & (umax - 1)) != 0) {

    /* Ceiling under which ZEND_LONG_MAX % max == 0 */

    zend_ulong limit = ZEND_ULONG_MAX - (ZEND_ULONG_MAX % umax) - 1;

    /* Discard numbers over the limit to avoid modulo bias */

    while (trial > limit) {

      if (php_random_bytes(&trial, sizeof(trial), should_throw) == FAILURE) {

        return FAILURE;

      }

    }

  }

  *result = (zend_long)((trial % umax) + min);

  return SUCCESS;

}

/* }}} */

/* {{{ Return an arbitrary pseudo-random integer */

PHP_FUNCTION(random_int)

{

  zend_long min;

  zend_long max;

  zend_long result;

  ZEND_PARSE_PARAMETERS_START(2, 2)

    Z_PARAM_LONG(min)

    Z_PARAM_LONG(max)

  ZEND_PARSE_PARAMETERS_END();

  if (min > max) {

    zend_argument_value_error(1, "must be less than or equal to argument #2 ($max)");

    RETURN_THROWS();

  }

  if (php_random_int_throw(min, max, &result) == FAILURE) {

    RETURN_THROWS();

  }

  RETURN_LONG(result);

}

/* }}} */