/* Copyright (c) 2016, Google Inc.

 *

 * Permission to use, copy, modify, and/or distribute this software for any

 * purpose with or without fee is hereby granted, provided that the above

 * copyright notice and this permission notice appear in all copies.

 *

 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES

 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF

 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY

 * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES

 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION

 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN

 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */

#include <openssl/pool.h>

#include <assert.h>

#include <string.h>

#include <openssl/bytestring.h>

#include <openssl/mem.h>

#include <openssl/rand.h>

#include <openssl/siphash.h>

#include <openssl/thread.h>

#include "../internal.h"

#include "internal.h"

static uint32_t CRYPTO_BUFFER_hash(const CRYPTO_BUFFER *buf) {

  return (uint32_t)SIPHASH_24(buf->pool->hash_key, buf->data, buf->len);

}

static int CRYPTO_BUFFER_cmp(const CRYPTO_BUFFER *a, const CRYPTO_BUFFER *b) {

  // Only |CRYPTO_BUFFER|s from the same pool have compatible hashes.

  assert(a->pool != NULL);

  assert(a->pool == b->pool);

  if (a->len != b->len) {

    return 1;

  }

  return OPENSSL_memcmp(a->data, b->data, a->len);

}

CRYPTO_BUFFER_POOL* CRYPTO_BUFFER_POOL_new(void) {

  CRYPTO_BUFFER_POOL *pool = OPENSSL_zalloc(sizeof(CRYPTO_BUFFER_POOL));

  if (pool == NULL) {

    return NULL;

  }

  pool->bufs = lh_CRYPTO_BUFFER_new(CRYPTO_BUFFER_hash, CRYPTO_BUFFER_cmp);

  if (pool->bufs == NULL) {

    OPENSSL_free(pool);

    return NULL;

  }

  CRYPTO_MUTEX_init(&pool->lock);

  RAND_bytes((uint8_t *)&pool->hash_key, sizeof(pool->hash_key));

  return pool;

}

void CRYPTO_BUFFER_POOL_free(CRYPTO_BUFFER_POOL *pool) {

  if (pool == NULL) {

    return;

  }

#if !defined(NDEBUG)

  CRYPTO_MUTEX_lock_write(&pool->lock);

  assert(lh_CRYPTO_BUFFER_num_items(pool->bufs) == 0);

  CRYPTO_MUTEX_unlock_write(&pool->lock);

#endif

  lh_CRYPTO_BUFFER_free(pool->bufs);

  CRYPTO_MUTEX_cleanup(&pool->lock);

  OPENSSL_free(pool);

}

static void crypto_buffer_free_object(CRYPTO_BUFFER *buf) {

  if (!buf->data_is_static) {

    OPENSSL_free(buf->data);

  }

  OPENSSL_free(buf);

}

static CRYPTO_BUFFER *crypto_buffer_new(const uint8_t *data, size_t len,

                                        int data_is_static,

                                        CRYPTO_BUFFER_POOL *pool) {

  if (pool != NULL) {

    CRYPTO_BUFFER tmp;

    tmp.data = (uint8_t *) data;

    tmp.len = len;

    tmp.pool = pool;

    CRYPTO_MUTEX_lock_read(&pool->lock);

    CRYPTO_BUFFER *duplicate = lh_CRYPTO_BUFFER_retrieve(pool->bufs, &tmp);

    if (data_is_static && duplicate != NULL && !duplicate->data_is_static) {

      // If the new |CRYPTO_BUFFER| would have static data, but the duplicate

      // does not, we replace the old one with the new static version.

      duplicate = NULL;

    }

    if (duplicate != NULL) {

      CRYPTO_refcount_inc(&duplicate->references);

    }

    CRYPTO_MUTEX_unlock_read(&pool->lock);

    if (duplicate != NULL) {

      return duplicate;

    }

  }

  CRYPTO_BUFFER *const buf = OPENSSL_zalloc(sizeof(CRYPTO_BUFFER));

  if (buf == NULL) {

    return NULL;

  }

  if (data_is_static) {

    buf->data = (uint8_t *)data;

    buf->data_is_static = 1;

  } else {

    buf->data = OPENSSL_memdup(data, len);

    if (len != 0 && buf->data == NULL) {

      OPENSSL_free(buf);

      return NULL;

    }

  }

  buf->len = len;

  buf->references = 1;

  if (pool == NULL) {

    return buf;

  }

  buf->pool = pool;

  CRYPTO_MUTEX_lock_write(&pool->lock);

  CRYPTO_BUFFER *duplicate = lh_CRYPTO_BUFFER_retrieve(pool->bufs, buf);

  if (data_is_static && duplicate != NULL && !duplicate->data_is_static) {

    // If the new |CRYPTO_BUFFER| would have static data, but the duplicate does

    // not, we replace the old one with the new static version.

    duplicate = NULL;

  }

  int inserted = 0;

  if (duplicate == NULL) {

    CRYPTO_BUFFER *old = NULL;

    inserted = lh_CRYPTO_BUFFER_insert(pool->bufs, &old, buf);

    // |old| may be non-NULL if a match was found but ignored. |pool->bufs| does

    // not increment refcounts, so there is no need to clean up after the

    // replacement.

  } else {

    CRYPTO_refcount_inc(&duplicate->references);

  }

  CRYPTO_MUTEX_unlock_write(&pool->lock);

  if (!inserted) {

    // We raced to insert |buf| into the pool and lost, or else there was an

    // error inserting.

    crypto_buffer_free_object(buf);

    return duplicate;

  }

  return buf;

}

CRYPTO_BUFFER *CRYPTO_BUFFER_new(const uint8_t *data, size_t len,

                                 CRYPTO_BUFFER_POOL *pool) {

  return crypto_buffer_new(data, len, /*data_is_static=*/0, pool);

}

CRYPTO_BUFFER *CRYPTO_BUFFER_alloc(uint8_t **out_data, size_t len) {

  CRYPTO_BUFFER *const buf = OPENSSL_zalloc(sizeof(CRYPTO_BUFFER));

  if (buf == NULL) {

    return NULL;

  }

  buf->data = OPENSSL_malloc(len);

  if (len != 0 && buf->data == NULL) {

    OPENSSL_free(buf);

    return NULL;

  }

  buf->len = len;

  buf->references = 1;

  *out_data = buf->data;

  return buf;

}

CRYPTO_BUFFER *CRYPTO_BUFFER_new_from_CBS(const CBS *cbs,

                                          CRYPTO_BUFFER_POOL *pool) {

  return CRYPTO_BUFFER_new(CBS_data(cbs), CBS_len(cbs), pool);

}

CRYPTO_BUFFER *CRYPTO_BUFFER_new_from_static_data_unsafe(

    const uint8_t *data, size_t len, CRYPTO_BUFFER_POOL *pool) {

  return crypto_buffer_new(data, len, /*data_is_static=*/1, pool);

}

void CRYPTO_BUFFER_free(CRYPTO_BUFFER *buf) {

  if (buf == NULL) {

    return;

  }

  CRYPTO_BUFFER_POOL *const pool = buf->pool;

  if (pool == NULL) {

    if (CRYPTO_refcount_dec_and_test_zero(&buf->references)) {

      // If a reference count of zero is observed, there cannot be a reference

      // from any pool to this buffer and thus we are able to free this

      // buffer.

      crypto_buffer_free_object(buf);

    }

    return;

  }

  CRYPTO_MUTEX_lock_write(&pool->lock);

  if (!CRYPTO_refcount_dec_and_test_zero(&buf->references)) {

    CRYPTO_MUTEX_unlock_write(&buf->pool->lock);

    return;

  }

  // We have an exclusive lock on the pool, therefore no concurrent lookups can

  // find this buffer and increment the reference count. Thus, if the count is

  // zero there are and can never be any more references and thus we can free

  // this buffer.

  //

  // Note it is possible |buf| is no longer in the pool, if it was replaced by a

  // static version. If that static version was since removed, it is even

  // possible for |found| to be NULL.

  CRYPTO_BUFFER *found = lh_CRYPTO_BUFFER_retrieve(pool->bufs, buf);

  if (found == buf) {

    found = lh_CRYPTO_BUFFER_delete(pool->bufs, buf);

    assert(found == buf);

    (void)found;

  }

  CRYPTO_MUTEX_unlock_write(&buf->pool->lock);

  crypto_buffer_free_object(buf);

}

int CRYPTO_BUFFER_up_ref(CRYPTO_BUFFER *buf) {

  // This is safe in the case that |buf->pool| is NULL because it's just

  // standard reference counting in that case.

  //

  // This is also safe if |buf->pool| is non-NULL because, if it were racing

  // with |CRYPTO_BUFFER_free| then the two callers must have independent

  // references already and so the reference count will never hit zero.

  CRYPTO_refcount_inc(&buf->references);

  return 1;

}

const uint8_t *CRYPTO_BUFFER_data(const CRYPTO_BUFFER *buf) {

  return buf->data;

}

size_t CRYPTO_BUFFER_len(const CRYPTO_BUFFER *buf) {

  return buf->len;

}

void CRYPTO_BUFFER_init_CBS(const CRYPTO_BUFFER *buf, CBS *out) {

  CBS_init(out, buf->data, buf->len);

}