// Copyright 2016 The BoringSSL Authors

//

// 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

//

//     https://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.

#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 "../internal.h"

#include "../mem_internal.h"

#include "internal.h"

using namespace bssl;

static uint32_t CRYPTO_BUFFER_hash(const CryptoBuffer *buf) {

  // This function must be called while there is a read or write lock on the

  // pool, so it is safe to read |pool_|.

  return buf->pool_handle_->pool_->Hash(buf->span());

}

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

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

  assert(a->pool_handle_ != nullptr);

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

  return a->span() == b->span() ? 0 : 1;

}

CryptoBufferPool::CryptoBufferPool() {

  RAND_bytes(reinterpret_cast<uint8_t *>(&hash_key_), sizeof(hash_key_));

}

CryptoBufferPool::~CryptoBufferPool() {

  if (handle_) {

    MutexWriteLock lock(&handle_->lock_);

    handle_->pool_ = nullptr;

  }

  lh_CryptoBuffer_free(bufs_);

}

uint32_t CryptoBufferPool::Hash(Span<const uint8_t> data) const {

  return static_cast<uint32_t>(SIPHASH_24(hash_key_, data.data(), data.size()));

}

CryptoBuffer *CryptoBufferPool::FindBufferLocked(uint32_t hash,

                                                 Span<const uint8_t> data) {

  return lh_CryptoBuffer_retrieve_key(

      bufs_, &data, hash,

      [](const void *key_v, const CryptoBuffer *buf) -> int {

        Span<const uint8_t> key =

            *static_cast<const Span<const uint8_t> *>(key_v);

        return key == buf->span() ? 0 : 1;

      });

}

CRYPTO_BUFFER_POOL *CRYPTO_BUFFER_POOL_new() {

  auto pool = MakeUnique<CryptoBufferPool>();

  if (pool == nullptr) {

    return nullptr;

  }

  pool->bufs_ = lh_CryptoBuffer_new(CRYPTO_BUFFER_hash, CRYPTO_BUFFER_cmp);

  pool->handle_ = MakeUnique<CryptoBufferPoolHandle>(pool.get());

  if (pool->bufs_ == nullptr || pool->handle_ == nullptr) {

    return nullptr;

  }

  return pool.release();

}

void CRYPTO_BUFFER_POOL_free(CRYPTO_BUFFER_POOL *pool) {

  Delete(FromOpaque(pool));

}

void CryptoBuffer::UpRefInternal() {

  // 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(&references_);

}

void CryptoBuffer::DecRefInternal() {

  // If there is a pool, decrementing the refcount must synchronize with it.

  if (pool_handle_ == nullptr) {

    if (!CRYPTO_refcount_dec_and_test_zero(&references_)) {

      return;

    }

  } else {

    MutexWriteLock lock(&pool_handle_->lock_);

    if (!CRYPTO_refcount_dec_and_test_zero(&references_)) {

      return;

    }

    // We have an exclusive lock on the pool handle, 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. It is possible the pool was already destroyed,

    // but it cannot be destroyed concurrently.

    //

    // 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.

    if (CryptoBufferPool *pool = pool_handle_->pool_; pool != nullptr) {

      CryptoBuffer *found = lh_CryptoBuffer_retrieve(pool->bufs_, this);

      if (found == this) {

        found = lh_CryptoBuffer_delete(pool->bufs_, this);

        assert(found == this);

        (void)found;

      }

    }

  }

  this->~CryptoBuffer();

  OPENSSL_free(this);

}

CryptoBuffer::~CryptoBuffer() {

  if (!data_is_static_) {

    OPENSSL_free(data_);

  }

}

static UniquePtr<CryptoBuffer> crypto_buffer_new(Span<const uint8_t> data,

                                                 bool data_is_static) {

  UniquePtr<CryptoBuffer> buf = MakeUnique<CryptoBuffer>();

  if (buf == nullptr) {

    return nullptr;

  }

  if (data_is_static) {

    buf->data_ = const_cast<uint8_t *>(data.data());

    buf->data_is_static_ = true;

  } else {

    buf->data_ =

        static_cast<uint8_t *>(OPENSSL_memdup(data.data(), data.size()));

    if (!data.empty() && buf->data_ == nullptr) {

      return nullptr;

    }

  }

  buf->len_ = data.size();

  return buf;

}

static UniquePtr<CryptoBuffer> crypto_buffer_new_with_pool(

    Span<const uint8_t> data, bool data_is_static, CryptoBufferPool *pool) {

  if (pool == nullptr) {

    return crypto_buffer_new(data, data_is_static);

  }

  const uint32_t hash = pool->Hash(data);

  {

    // Look for a matching buffer in the pool.

    MutexReadLock lock(&pool->handle_->lock_);

    CryptoBuffer *duplicate = pool->FindBufferLocked(hash, data);

    if (data_is_static && duplicate != nullptr && !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 = nullptr;

    }

    if (duplicate != nullptr) {

      return UpRef(duplicate);

    }

  }

  UniquePtr<CryptoBuffer> buf = crypto_buffer_new(data, data_is_static);

  if (buf == nullptr) {

    return nullptr;

  }

  MutexWriteLock lock(&pool->handle_->lock_);

  CryptoBuffer *duplicate = pool->FindBufferLocked(hash, data);

  if (data_is_static && duplicate != nullptr && !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 = nullptr;

  }

  if (duplicate != nullptr) {

    return UpRef(duplicate);

  }

  // Insert |buf| into the pool. Note |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.

  buf->pool_handle_ = UpRef(pool->handle_);

  CryptoBuffer *old = nullptr;

  if (!lh_CryptoBuffer_insert(pool->bufs_, &old, buf.get())) {

    buf->pool_handle_ = nullptr;  // No need to synchronize with the pool.

    return nullptr;

  }

  return buf;

}

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

                                 CRYPTO_BUFFER_POOL *pool) {

  return crypto_buffer_new_with_pool(Span(data, len), /*data_is_static=*/false,

                                     FromOpaque(pool))

      .release();

}

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

  auto buf = MakeUnique<CryptoBuffer>();

  if (buf == nullptr) {

    return nullptr;

  }

  buf->data_ = reinterpret_cast<uint8_t *>(OPENSSL_malloc(len));

  if (len != 0 && buf->data_ == nullptr) {

    return nullptr;

  }

  buf->len_ = len;

  *out_data = buf->data_;

  return buf.release();

}

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_with_pool(Span(data, len), /*data_is_static=*/true,

                                     FromOpaque(pool))

      .release();

}

void CRYPTO_BUFFER_free(CRYPTO_BUFFER *buf) {

  if (buf != nullptr) {

    FromOpaque(buf)->DecRefInternal();

  }

}

int CRYPTO_BUFFER_up_ref(CRYPTO_BUFFER *buf) {

  FromOpaque(buf)->UpRefInternal();

  return 1;

}

const uint8_t *CRYPTO_BUFFER_data(const CRYPTO_BUFFER *buf) {

  return FromOpaque(buf)->data_;

}

size_t CRYPTO_BUFFER_len(const CRYPTO_BUFFER *buf) {

  return FromOpaque(buf)->len_;

}

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

  *out = FromOpaque(buf)->span();

}