/*
Copyright (c) 2013. The YARA Authors. All Rights Reserved.

Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation and/or
other materials provided with the distribution.

3. Neither the name of the copyright holder nor the names of its contributors
may be used to endorse or promote products derived from this software without
specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

#include <assert.h>
#include <string.h>

#include <yara/utils.h>
#include <yara/integers.h>
#include <yara/hash.h>
#include <yara/mem.h>
#include <yara/error.h>

// Constant-time left rotate that does not invoke undefined behavior.
// http://blog.regehr.org/archives/1063
static uint32_t rotl32(uint32_t x, uint32_t shift) {
  assert(shift < 32);
  return (x << shift) | (x >> (-shift & 31));
}

#define ROTATE_INT32(x, shift) \
    rotl32(x, shift % 32)

uint32_t byte_to_int32[]  =
{
  0xC3113E7F,0x4C353C5F,0x7423810B,0x258D264E,0xDAD39DED,0x75D0B694,0x98CE1216,
  0x93334482,0xC5C48EA5,0xF57E0E8B,0x5D7F3723,0x396B1B24,0xA8883D9F,0xB2A74A00,
  0xF8E171AE,0x3F01FBAB,0x5C1840CB,0xDDD833C4,0x8D8CCA34,0x32EF223A,0x1A05B871,
  0x9A9B6BFC,0x50406A0C,0xE7E1FC04,0x5E07D7F6,0x80B83660,0x20892A62,0xB2C6FEA6,
  0x6CEC7CAA,0x182F764B,0x3B0353E7,0x57FC2520,0x4B6812D4,0xACB654E4,0x23C75C04,
  0xB1DCD731,0xE3AF0733,0xF2366D39,0xC729671B,0xFF3BE6F2,0xABA37E34,0x3CDAFA38,
  0xAAD18D03,0xA8D35345,0x08E9A92C,0xF9324059,0x42D821BE,0x1BC152DD,0x5588811C,
  0x874A1F9A,0x6E83E9CD,0xDA6F3AF8,0x965D4670,0xA7A565C0,0x68D8A9AF,0xFC8FD8FD,
  0x8FF99FF9,0x4C9B42AE,0x2D066A8D,0x4D1802F7,0x557032B2,0x12BCF371,0xDC29D5AE,
  0x72EA361F,0xE2835B0B,0xDFC58966,0x13B0F34D,0x3FA02BCD,0xBF282E3D,0x7DC877F5,
  0xF4848A32,0x861E35F5,0x7FFA0D7F,0x515F2E4E,0x6B235D5C,0x55F46E24,0x35AD2C99,
  0x072654A8,0x05163F0F,0x9317B11A,0xAED1FC10,0x989444F0,0xDB3E1814,0x446C0CF1,
  0x660BF511,0x2F227D3A,0xFDBA0539,0xC649E621,0x5204D7CE,0x5FA386D0,0xE5F22005,
  0x97B6C8A1,0x4AB69EC2,0x5C7CA70D,0x39A48EC6,0x7BACF378,0x8D0ED3D1,0xE39DE582,
  0xC5FBE2AB,0x37E3D2D0,0x06F44724,0x73144144,0xBA57E905,0xB05B4307,0xAEED8D97,
  0xA68CCAC4,0xE30DA57E,0xED0F194B,0x8C2B9B7A,0x814575D5,0x79588493,0x81D3712A,
  0x3FA892F2,0x80F0BB94,0x44EAF51A,0x4E05F1D4,0xFC69F858,0x775E8D60,0x22B20DD7,
  0x170A87EA,0x1077DE52,0x3D5EC9FB,0x0B6EB1E5,0xF2F9CCAF,0xA76C7DEB,0xD8C2D873,
  0xF438C592,0x6239FEEC,0x26D3D2A9,0x30F6FADF,0x4B2984CC,0x6257F3DA,0x0E0583E2,
  0x143E5E61,0xBB2732BF,0x9653217A,0x027A84EA,0x95C9AE8B,0x89B8B82B,0x9F286485,
  0x29F622FE,0x52A3196B,0x8392D95F,0x33A79167,0xF5DEE92A,0x6E397DB9,0x11931C01,
  0x8DD2CD3B,0xF9E6003D,0xAB955AF4,0xD38725F9,0xDCF6F8AE,0x7667A958,0xE67AD995,
  0xB7CF979A,0xD88EBE5B,0x5BA889F0,0x078BDD90,0x447238F9,0x3135F672,0x187B95A8,
  0x0B7D5751,0xACD59D2A,0x9C5D1929,0x579E5022,0xEA90499B,0x59901800,0x82237DB5,
  0x7A375509,0xACA9A22A,0xEC96E649,0x69339DB0,0x081D0D9B,0xD72FB8B9,0xA4184653,
  0xC057321D,0xED19CAB9,0xB48F1E3E,0xB9DAC51E,0xDAED2FC7,0x7598CBBD,0x208DF346,
  0x044BE6EC,0x1C63E6EB,0xA15F64C1,0xE024A061,0x68309584,0x0758A68D,0xF274E9AE,
  0x0ABEA0CC,0xED4FB267,0x63D6EC46,0x9F28E026,0xF0694A17,0x9D6E9115,0xC4600FAD,
  0x5B121E99,0xD6B4A13B,0xF5364B8A,0x8514B254,0x0182F8DD,0xDB09F90B,0x78C70B32,
  0xD8EC3B02,0x8CD7084D,0xA4439838,0x72F35A3D,0x200B48A5,0xE2351444,0xA5552F5F,
  0xD8C1E746,0x0FE5EF3C,0xB6A47063,0x61F4E68B,0x08FED99B,0x7E461445,0x43CB8380,
  0x28BA03C8,0x21A7A2E2,0x43437ED6,0x2A9E6670,0x89B4A106,0xC6C2F4EE,0x9C4063CC,
  0x2FA0DF6C,0xB54DC409,0xCF01538F,0x616431D7,0x02CB0E4D,0x44FFF425,0xAAD5188E,
  0x0742E9BC,0xFFF41353,0x130F0A15,0x787BDC10,0x4A327B72,0x702989F7,0x5F704798,
  0x8156A1BB,0x2BCA3E74,0x1911A8C4,0x5E1F27D3,0x07949DC7,0xF24C2056,0xB4299EE6,
  0x9C7045D9,0xA8BF6307,0x7454AAD2,0x256425E5,0xD87DEF67,0xCFE95452,0xE7548DF7,
  0xA84956C7,0xD8402C60,0xCFBD0373,0x6B6CDAFE
};


uint32_t yr_hash(
    uint32_t seed,
    const void* buffer,
    size_t len)
{
  const uint8_t* b = (uint8_t*) buffer;

  uint32_t result = seed;
  size_t i;

  if (len == 0)
    return result;

  for (i = len - 1; i > 0; i--)
  {
    result ^= ROTATE_INT32(byte_to_int32[*b], i);
    b++;
  }

  result ^= byte_to_int32[*b];
  return result;
}

// _yr_hash_table_lookup
//
// Return the value associated to a given key and optionally remove it from
// the hash table. Key can be any byte sequence, namespace is a null-terminated
// string, and remove is a boolean.

static void* _yr_hash_table_lookup(
    YR_HASH_TABLE* table,
    const void* key,
    size_t key_length,
    const char* ns,
    int remove)
{
  YR_HASH_TABLE_ENTRY* entry;
  YR_HASH_TABLE_ENTRY* prev_entry;

  void* result;

  uint32_t bucket_index = yr_hash(0, key, key_length);

  if (ns != NULL)
    bucket_index = yr_hash(bucket_index, (uint8_t*) ns, strlen(ns));

  bucket_index = bucket_index % table->size;
  prev_entry = NULL;
  entry = table->buckets[bucket_index];

  while (entry != NULL)
  {
    int key_match = (
        (entry->key_length == key_length) &&
        (memcmp(entry->key, key, key_length) == 0));

    int ns_match = (
        (entry->ns == ns) ||
        (entry->ns != NULL && ns != NULL && strcmp(entry->ns, ns) == 0));

    if (key_match && ns_match)
    {
      result = entry->value;

      if (remove)
      {
        if (prev_entry == NULL)
          table->buckets[bucket_index] = entry->next;
        else
          prev_entry->next = entry->next;

        if (entry->ns != NULL)
          yr_free(entry->ns);

        yr_free(entry->key);
        yr_free(entry);
      }

      return result;
    }

    prev_entry = entry;
    entry = entry->next;
  }

  return NULL;
}


YR_API int yr_hash_table_create(
    int size,
    YR_HASH_TABLE** table)
{
  YR_HASH_TABLE* new_table;
  int i;

  new_table = (YR_HASH_TABLE*) yr_malloc(
      sizeof(YR_HASH_TABLE) + size * sizeof(YR_HASH_TABLE_ENTRY*));

  if (new_table == NULL)
    return ERROR_INSUFFICIENT_MEMORY;

  new_table->size = size;

  for (i = 0; i < size; i++)
    new_table->buckets[i] = NULL;

  *table = new_table;

  return ERROR_SUCCESS;
}


YR_API void yr_hash_table_clean(
    YR_HASH_TABLE* table,
    YR_HASH_TABLE_FREE_VALUE_FUNC free_value)
{
  YR_HASH_TABLE_ENTRY* entry;
  YR_HASH_TABLE_ENTRY* next_entry;

  int i;

  if (table == NULL)
    return;

  for (i = 0; i < table->size; i++)
  {
    entry = table->buckets[i];

    while (entry != NULL)
    {
      next_entry = entry->next;

      if (free_value != NULL)
        free_value(entry->value);

      if (entry->ns != NULL)
        yr_free(entry->ns);

      yr_free(entry->key);
      yr_free(entry);

      entry = next_entry;
    }

    table->buckets[i] = NULL;
  }
}


YR_API void yr_hash_table_destroy(
    YR_HASH_TABLE* table,
    YR_HASH_TABLE_FREE_VALUE_FUNC free_value)
{
  yr_hash_table_clean(table, free_value);
  yr_free(table);
}


YR_API void* yr_hash_table_lookup_raw_key(
    YR_HASH_TABLE* table,
    const void* key,
    size_t key_length,
    const char* ns)
{
  return _yr_hash_table_lookup(table, key, key_length, ns, false);
}


YR_API void* yr_hash_table_remove_raw_key(
    YR_HASH_TABLE* table,
    const void* key,
    size_t key_length,
    const char* ns)
{
  return _yr_hash_table_lookup(table, key, key_length, ns, true);
}


YR_API int yr_hash_table_add_raw_key(
    YR_HASH_TABLE* table,
    const void* key,
    size_t key_length,
    const char* ns,
    void* value)
{
  YR_HASH_TABLE_ENTRY* entry;
  uint32_t bucket_index;

  entry = (YR_HASH_TABLE_ENTRY*) yr_malloc(sizeof(YR_HASH_TABLE_ENTRY));

  if (entry == NULL)
    return ERROR_INSUFFICIENT_MEMORY;

  entry->key = yr_malloc(key_length);

  if (entry->key == NULL)
  {
    yr_free(entry);
    return ERROR_INSUFFICIENT_MEMORY;
  }

  if (ns != NULL)
  {
    entry->ns = yr_strdup(ns);

    if (entry->ns == NULL)
    {
      yr_free(entry->key);
      yr_free(entry);

      return ERROR_INSUFFICIENT_MEMORY;
    }
  }
  else
  {
    entry->ns = NULL;
  }

  entry->key_length = key_length;
  entry->value = value;

  memcpy(entry->key, key, key_length);

  bucket_index = yr_hash(0, key, key_length);

  if (ns != NULL)
    bucket_index = yr_hash(bucket_index, (uint8_t*) ns, strlen(ns));

  bucket_index = bucket_index % table->size;

  entry->next = table->buckets[bucket_index];
  table->buckets[bucket_index] = entry;

  return ERROR_SUCCESS;
}


YR_API void* yr_hash_table_lookup(
    YR_HASH_TABLE* table,
    const char* key,
    const char* ns)
{
  return yr_hash_table_lookup_raw_key(
      table,
      (void*) key,
      strlen(key),
      ns);
}


YR_API void* yr_hash_table_remove(
    YR_HASH_TABLE* table,
    const char* key,
    const char* ns)
{
  return yr_hash_table_remove_raw_key(
      table,
      (void*) key,
      strlen(key),
      ns);
}


YR_API int yr_hash_table_add(
    YR_HASH_TABLE* table,
    const char* key,
    const char* ns,
    void* value)
{
  return yr_hash_table_add_raw_key(
      table,
      (void*) key,
      strlen(key),
      ns,
      value);
}
