/*

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

   | Copyright © The PHP Group and Contributors.                          |

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

   | This source file is subject to the Modified BSD License that is      |

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

   | through the World Wide Web at <https://www.php.net/license/>.        |

   |                                                                      |

   | SPDX-License-Identifier: BSD-3-Clause                                |

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

   | Author: Go Kudo <zeriyoshi@php.net>                                  |

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

*/

#ifdef HAVE_CONFIG_H

# include "config.h"

#endif

#include "php.h"

#include "php_random.h"

#include "ext/standard/php_array.h"

#include "ext/standard/php_string.h"

#include "Zend/zend_enum.h"

#include "Zend/zend_exceptions.h"

#include "zend_portability.h"

static inline void randomizer_common_init(php_random_randomizer *randomizer, zend_object *engine_object) {

  if (engine_object->ce->type == ZEND_INTERNAL_CLASS) {

    /* Internal classes always php_random_engine struct */

    php_random_engine *engine = php_random_engine_from_obj(engine_object);

    /* Copy engine pointers */

    randomizer->engine = engine->engine;

  } else {

    /* Self allocation */

    php_random_status_state_user *state = php_random_status_alloc(&php_random_algo_user, false);

    randomizer->engine = (php_random_algo_with_state){

      .algo = &php_random_algo_user,

      .state = state,

    };

    /* Create compatible state */

    state->object = engine_object;

    state->generate_method = zend_hash_str_find_ptr(&engine_object->ce->function_table, "generate", strlen("generate"));

    /* Mark self-allocated for memory management */

    randomizer->is_userland_algo = true;

  }

}

/* {{{ Random\Randomizer::__construct() */

PHP_METHOD(Random_Randomizer, __construct)

{

  php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);

  zval engine;

  zval *param_engine = NULL;

  ZEND_PARSE_PARAMETERS_START(0, 1)

    Z_PARAM_OPTIONAL

    Z_PARAM_OBJECT_OF_CLASS_OR_NULL(param_engine, random_ce_Random_Engine);

  ZEND_PARSE_PARAMETERS_END();

  if (param_engine != NULL) {

    ZVAL_COPY(&engine, param_engine);

  } else {

    /* Create default RNG instance */

    object_init_ex(&engine, random_ce_Random_Engine_Secure);

  }

  zend_update_property(random_ce_Random_Randomizer, Z_OBJ_P(ZEND_THIS), "engine", strlen("engine"), &engine);

  OBJ_RELEASE(Z_OBJ_P(&engine));

  if (EG(exception)) {

    RETURN_THROWS();

  }

  randomizer_common_init(randomizer, Z_OBJ_P(&engine));

}

/* }}} */

/* {{{ Generate a float in [0, 1) */

PHP_METHOD(Random_Randomizer, nextFloat)

{

  php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);

  php_random_algo_with_state engine = randomizer->engine;

  uint64_t result;

  size_t total_size;

  ZEND_PARSE_PARAMETERS_NONE();

  result = 0;

  total_size = 0;

  do {

    php_random_result r = engine.algo->generate(engine.state);

    result = result | (r.result << (total_size * 8));

    total_size += r.size;

    if (EG(exception)) {

      RETURN_THROWS();

    }

  } while (total_size < sizeof(uint64_t));

  /* A double has 53 bits of precision, thus we must not

   * use the full 64 bits of the uint64_t, because we would

   * introduce a bias / rounding error.

   */

#if DBL_MANT_DIG != 53

# error "Random_Randomizer::nextFloat(): Requires DBL_MANT_DIG == 53 to work."

#endif

  const double step_size = 1.0 / (1ULL << 53);

  /* Use the upper 53 bits, because some engine's lower bits

   * are of lower quality.

   */

  result = (result >> 11);

  RETURN_DOUBLE(step_size * result);

}

/* }}} */

/* {{{ Generates a random float within a configurable interval.

 *

 * This method uses the γ-section algorithm by Frédéric Goualard.

 */

PHP_METHOD(Random_Randomizer, getFloat)

{

  php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);

  double min, max;

  zend_enum_Random_IntervalBoundary bounds_type = ZEND_ENUM_Random_IntervalBoundary_ClosedOpen;

  ZEND_PARSE_PARAMETERS_START(2, 3)

    Z_PARAM_DOUBLE(min)

    Z_PARAM_DOUBLE(max)

    Z_PARAM_OPTIONAL

    Z_PARAM_ENUM(bounds_type, random_ce_Random_IntervalBoundary);

  ZEND_PARSE_PARAMETERS_END();

  if (!zend_finite(min)) {

    zend_argument_value_error(1, "must be finite");

    RETURN_THROWS();

  }

  if (!zend_finite(max)) {

    zend_argument_value_error(2, "must be finite");

    RETURN_THROWS();

  }

  switch (bounds_type) {

  case ZEND_ENUM_Random_IntervalBoundary_ClosedOpen:

    if (UNEXPECTED(max <= min)) {

      zend_argument_value_error(2, "must be greater than argument #1 ($min)");

      RETURN_THROWS();

    }

    RETURN_DOUBLE(php_random_gammasection_closed_open(randomizer->engine, min, max));

  case ZEND_ENUM_Random_IntervalBoundary_ClosedClosed:

    if (UNEXPECTED(max < min)) {

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

      RETURN_THROWS();

    }

    RETURN_DOUBLE(php_random_gammasection_closed_closed(randomizer->engine, min, max));

  case ZEND_ENUM_Random_IntervalBoundary_OpenClosed:

    if (UNEXPECTED(max <= min)) {

      zend_argument_value_error(2, "must be greater than argument #1 ($min)");

      RETURN_THROWS();

    }

    RETURN_DOUBLE(php_random_gammasection_open_closed(randomizer->engine, min, max));

  case ZEND_ENUM_Random_IntervalBoundary_OpenOpen:

    if (UNEXPECTED(max <= min)) {

      zend_argument_value_error(2, "must be greater than argument #1 ($min)");

      RETURN_THROWS();

    }

    RETVAL_DOUBLE(php_random_gammasection_open_open(randomizer->engine, min, max));

    if (UNEXPECTED(isnan(Z_DVAL_P(return_value)))) {

      zend_value_error("The given interval is empty, there are no floats between argument #1 ($min) and argument #2 ($max)");

      RETURN_THROWS();

    }

    return;

  }

}

/* }}} */

/* {{{ Generate positive random number */

PHP_METHOD(Random_Randomizer, nextInt)

{

  php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);

  php_random_algo_with_state engine = randomizer->engine;

  ZEND_PARSE_PARAMETERS_NONE();

  php_random_result result = engine.algo->generate(engine.state);

  if (EG(exception)) {

    RETURN_THROWS();

  }

  if (result.size > sizeof(zend_long)) {

    zend_throw_exception(random_ce_Random_RandomException, "Generated value exceeds size of int", 0);

    RETURN_THROWS();

  }

  RETURN_LONG((zend_long) (result.result >> 1));

}

/* }}} */

/* {{{ Generate random number in range */

PHP_METHOD(Random_Randomizer, getInt)

{

  php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);

  php_random_algo_with_state engine = randomizer->engine;

  uint64_t result;

  zend_long min, max;

  ZEND_PARSE_PARAMETERS_START(2, 2)

    Z_PARAM_LONG(min)

    Z_PARAM_LONG(max)

  ZEND_PARSE_PARAMETERS_END();

  if (UNEXPECTED(max < min)) {

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

    RETURN_THROWS();

  }

  if (UNEXPECTED(

    engine.algo->range == php_random_algo_mt19937.range

    && ((php_random_status_state_mt19937 *) engine.state)->mode != MT_RAND_MT19937

  )) {

    uint64_t r = php_random_algo_mt19937.generate(engine.state).result >> 1;

    /* This is an inlined version of the RAND_RANGE_BADSCALING macro that does not invoke UB when encountering

     * (max - min) > ZEND_LONG_MAX.

     */

    zend_ulong offset = (double) ( (double) max - min + 1.0) * (r / (PHP_MT_RAND_MAX + 1.0));

    result = (zend_long) (offset + min);

  } else {

    result = engine.algo->range(engine.state, min, max);

  }

  if (EG(exception)) {

    RETURN_THROWS();

  }

  RETURN_LONG((zend_long) result);

}

/* }}} */

/* {{{ Generate random bytes string in ordered length */

PHP_METHOD(Random_Randomizer, getBytes)

{

  php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);

  php_random_algo_with_state engine = randomizer->engine;

  zend_string *retval;

  zend_long user_length;

  size_t total_size = 0;

  ZEND_PARSE_PARAMETERS_START(1, 1)

    Z_PARAM_LONG(user_length)

  ZEND_PARSE_PARAMETERS_END();

  if (user_length < 1) {

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

    RETURN_THROWS();

  }

  size_t length = (size_t)user_length;

  retval = zend_string_alloc(length, 0);

  php_random_result result;

  while (total_size + 8 <= length) {

    result = engine.algo->generate(engine.state);

    if (EG(exception)) {

      zend_string_efree(retval);

      RETURN_THROWS();

    }

    /* If the result is not 64 bits, we can't use the fast path and

     * we don't attempt to use it in the future, because we don't

     * expect engines to change their output size.

     *

     * While it would be possible to always memcpy() the entire output,

     * using result.size as the length that would result in much worse

     * assembly, because it will actually emit a call to memcpy()

     * instead of just storing the 64 bit value at a memory offset.

     */

    if (result.size != 8) {

      goto non_64;

    }

#ifdef WORDS_BIGENDIAN

    uint64_t swapped = ZEND_BYTES_SWAP64(result.result);

    memcpy(ZSTR_VAL(retval) + total_size, &swapped, 8);

#else

    memcpy(ZSTR_VAL(retval) + total_size, &result.result, 8);

#endif

    total_size += 8;

  }

  while (total_size < length) {

    result = engine.algo->generate(engine.state);

    if (EG(exception)) {

      zend_string_efree(retval);

      RETURN_THROWS();

    }

 non_64:

    for (size_t i = 0; i < result.size; i++) {

      ZSTR_VAL(retval)[total_size++] = result.result & 0xff;

      result.result >>= 8;

      if (total_size >= length) {

        break;

      }

    }

  }

  ZSTR_VAL(retval)[length] = '\0';

  RETURN_NEW_STR(retval);

}

/* }}} */

/* {{{ Shuffling array */

PHP_METHOD(Random_Randomizer, shuffleArray)

{

  php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);

  zval *array;

  ZEND_PARSE_PARAMETERS_START(1, 1)

    Z_PARAM_ARRAY(array)

  ZEND_PARSE_PARAMETERS_END();

  RETVAL_ARR(zend_array_dup(Z_ARRVAL_P(array)));

  if (!php_array_data_shuffle(randomizer->engine, return_value)) {

    RETURN_THROWS();

  }

}

/* }}} */

/* {{{ Shuffling binary */

PHP_METHOD(Random_Randomizer, shuffleBytes)

{

  php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);

  zend_string *bytes;

  ZEND_PARSE_PARAMETERS_START(1, 1)

    Z_PARAM_STR(bytes)

  ZEND_PARSE_PARAMETERS_END();

  if (ZSTR_LEN(bytes) < 2) {

    RETURN_STR_COPY(bytes);

  }

  RETVAL_STRINGL(ZSTR_VAL(bytes), ZSTR_LEN(bytes));

  if (!php_binary_string_shuffle(randomizer->engine, Z_STRVAL_P(return_value), (zend_long) Z_STRLEN_P(return_value))) {

    RETURN_THROWS();

  }

}

/* }}} */

/* {{{ Pick keys */

PHP_METHOD(Random_Randomizer, pickArrayKeys)

{

  php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);

  zval *input, t;

  zend_long num_req;

  ZEND_PARSE_PARAMETERS_START(2, 2);

    Z_PARAM_ARRAY(input)

    Z_PARAM_LONG(num_req)

  ZEND_PARSE_PARAMETERS_END();

  if (!php_array_pick_keys(

    randomizer->engine,

    input,

    num_req,

    return_value,

    false)

  ) {

    RETURN_THROWS();

  }

  /* Keep compatibility, But the result is always an array */

  if (Z_TYPE_P(return_value) != IS_ARRAY) {

    ZVAL_COPY_VALUE(&t, return_value);

    array_init(return_value);

    zend_hash_next_index_insert(Z_ARRVAL_P(return_value), &t);

  }

}

/* }}} */

/* {{{ Get Random Bytes for String */

PHP_METHOD(Random_Randomizer, getBytesFromString)

{

  php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);

  php_random_algo_with_state engine = randomizer->engine;

  zend_long user_length;

  zend_string *source, *retval;

  size_t total_size = 0;

  ZEND_PARSE_PARAMETERS_START(2, 2);

    Z_PARAM_STR(source)

    Z_PARAM_LONG(user_length)

  ZEND_PARSE_PARAMETERS_END();

  const size_t source_length = ZSTR_LEN(source);

  const size_t max_offset = source_length - 1;

  if (source_length < 1) {

    zend_argument_must_not_be_empty_error(1);

    RETURN_THROWS();

  }

  if (user_length < 1) {

    zend_argument_value_error(2, "must be greater than 0");

    RETURN_THROWS();

  }

  size_t length = (size_t)user_length;

  retval = zend_string_alloc(length, 0);

  if (max_offset > 0xff) {

    while (total_size < length) {

      uint64_t offset = engine.algo->range(engine.state, 0, max_offset);

      if (EG(exception)) {

        zend_string_efree(retval);

        RETURN_THROWS();

      }

      ZSTR_VAL(retval)[total_size++] = ZSTR_VAL(source)[offset];

    }

  } else {

    uint64_t mask = max_offset;

    // Copy the top-most bit into all lower bits.

    // Shifting by 4 is sufficient, because max_offset

    // is guaranteed to fit in an 8-bit integer at this

    // point.

    mask |= mask >> 1;

    mask |= mask >> 2;

    mask |= mask >> 4;

    // Expand the lowest byte into all bytes.

    mask *= 0x0101010101010101;

    int failures = 0;

    while (total_size < length) {

      php_random_result result = engine.algo->generate(engine.state);

      if (EG(exception)) {

        zend_string_efree(retval);

        RETURN_THROWS();

      }

      uint64_t offsets = result.result & mask;

      for (size_t i = 0; i < result.size; i++) {

        uint64_t offset = offsets & 0xff;

        offsets >>= 8;

        if (offset > max_offset) {

          if (++failures > PHP_RANDOM_RANGE_ATTEMPTS) {

            zend_string_efree(retval);

            zend_throw_error(random_ce_Random_BrokenRandomEngineError, "Failed to generate an acceptable random number in %d attempts", PHP_RANDOM_RANGE_ATTEMPTS);

            RETURN_THROWS();

          }

          continue;

        }

        failures = 0;

        ZSTR_VAL(retval)[total_size++] = ZSTR_VAL(source)[offset];

        if (total_size >= length) {

          break;

        }

      }

    }

  }

  ZSTR_VAL(retval)[length] = '\0';

  RETURN_NEW_STR(retval);

}

/* }}} */

/* {{{ Random\Randomizer::__serialize() */

PHP_METHOD(Random_Randomizer, __serialize)

{

  php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);

  zval t;

  ZEND_PARSE_PARAMETERS_NONE();

  array_init(return_value);

  ZVAL_ARR(&t, zend_array_dup(zend_std_get_properties(&randomizer->std)));

  zend_hash_next_index_insert(Z_ARRVAL_P(return_value), &t);

}

/* }}} */

/* {{{ Random\Randomizer::__unserialize() */

PHP_METHOD(Random_Randomizer, __unserialize)

{

  php_random_randomizer *randomizer = Z_RANDOM_RANDOMIZER_P(ZEND_THIS);

  HashTable *d;

  zval *members_zv;

  zval *zengine;

  ZEND_PARSE_PARAMETERS_START(1, 1)

    Z_PARAM_ARRAY_HT(d);

  ZEND_PARSE_PARAMETERS_END();

  /* Verify the expected number of elements, this implicitly ensures that no additional elements are present. */

  if (zend_hash_num_elements(d) != 1) {

    zend_throw_exception(NULL, "Invalid serialization data for Random\\Randomizer object", 0);

    RETURN_THROWS();

  }

  members_zv = zend_hash_index_find(d, 0);

  if (!members_zv || Z_TYPE_P(members_zv) != IS_ARRAY) {

    zend_throw_exception(NULL, "Invalid serialization data for Random\\Randomizer object", 0);

    RETURN_THROWS();

  }

  object_properties_load(&randomizer->std, Z_ARRVAL_P(members_zv));

  if (EG(exception)) {

    zend_throw_exception(NULL, "Invalid serialization data for Random\\Randomizer object", 0);

    RETURN_THROWS();

  }

  zengine = zend_read_property(randomizer->std.ce, &randomizer->std, "engine", strlen("engine"), 1, NULL);

  if (Z_TYPE_P(zengine) != IS_OBJECT || !instanceof_function(Z_OBJCE_P(zengine), random_ce_Random_Engine)) {

    zend_throw_exception(NULL, "Invalid serialization data for Random\\Randomizer object", 0);

    RETURN_THROWS();

  }

  randomizer_common_init(randomizer, Z_OBJ_P(zengine));

}

/* }}} */