// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "mojo/services/network/udp_socket_impl.h"

#include <string.h>

#include <algorithm>
#include <limits>

#include "base/logging.h"
#include "base/memory/scoped_ptr.h"
#include "base/stl_util.h"
#include "mojo/services/network/net_adapters.h"
#include "mojo/services/network/net_address_type_converters.h"
#include "net/base/io_buffer.h"
#include "net/base/net_errors.h"

namespace mojo {

namespace {

const int kMaxReadSize = 128 * 1024;
const size_t kMaxWriteSize = 128 * 1024;
const size_t kMaxPendingSendRequestsUpperbound = 128;
const size_t kDefaultMaxPendingSendRequests = 32;

}  // namespace

UDPSocketImpl::PendingSendRequest::PendingSendRequest() {}

UDPSocketImpl::PendingSendRequest::~PendingSendRequest() {}

UDPSocketImpl::UDPSocketImpl()
    : socket_(nullptr, net::NetLog::Source()),
      bound_(false),
      remaining_recv_slots_(0),
      max_pending_send_requests_(kDefaultMaxPendingSendRequests) {
}

UDPSocketImpl::~UDPSocketImpl() {
  STLDeleteElements(&pending_send_requests_);
}

void UDPSocketImpl::AllowAddressReuse(
    const Callback<void(NetworkErrorPtr)>& callback) {
  if (bound_) {
    callback.Run(MakeNetworkError(net::ERR_FAILED));
    return;
  }

  socket_.AllowAddressReuse();
  callback.Run(MakeNetworkError(net::OK));
}

void UDPSocketImpl::Bind(
    NetAddressPtr addr,
    const Callback<void(NetworkErrorPtr, NetAddressPtr)>& callback) {
  if (bound_) {
    callback.Run(MakeNetworkError(net::ERR_FAILED), NetAddressPtr());
    return;
  }

  net::IPEndPoint ip_end_point = addr.To<net::IPEndPoint>();
  if (ip_end_point.GetFamily() == net::ADDRESS_FAMILY_UNSPECIFIED) {
    callback.Run(MakeNetworkError(net::ERR_ADDRESS_INVALID), NetAddressPtr());
    return;
  }

  int net_result = socket_.Listen(ip_end_point);
  if (net_result != net::OK) {
    callback.Run(MakeNetworkError(net_result), NetAddressPtr());
    return;
  }

  net::IPEndPoint bound_ip_end_point;
  NetAddressPtr bound_addr;
  net_result = socket_.GetLocalAddress(&bound_ip_end_point);
  if (net_result == net::OK)
    bound_addr = NetAddress::From(bound_ip_end_point);

  bound_ = true;
  callback.Run(MakeNetworkError(net::OK), bound_addr.Pass());
}

void UDPSocketImpl::SetSendBufferSize(
    uint32_t size,
    const Callback<void(NetworkErrorPtr)>& callback) {
  if (!bound_) {
    callback.Run(MakeNetworkError(net::ERR_FAILED));
    return;
  }

  if (size > static_cast<uint32_t>(std::numeric_limits<int32_t>::max()))
    size = std::numeric_limits<int32_t>::max();

  int net_result = socket_.SetSendBufferSize(static_cast<int32_t>(size));
  callback.Run(MakeNetworkError(net_result));
}

void UDPSocketImpl::SetReceiveBufferSize(
    uint32_t size,
    const Callback<void(NetworkErrorPtr)>& callback) {
  if (!bound_) {
    callback.Run(MakeNetworkError(net::ERR_FAILED));
    return;
  }

  if (size > static_cast<uint32_t>(std::numeric_limits<int32_t>::max()))
    size = std::numeric_limits<int32_t>::max();

  int net_result = socket_.SetReceiveBufferSize(static_cast<int32_t>(size));
  callback.Run(MakeNetworkError(net_result));
}

void UDPSocketImpl::NegotiateMaxPendingSendRequests(
    uint32_t requested_size,
    const Callback<void(uint32_t)>& callback) {
  if (requested_size != 0) {
    max_pending_send_requests_ =
      std::min(kMaxPendingSendRequestsUpperbound,
               static_cast<size_t>(requested_size));
  }
  callback.Run(static_cast<uint32_t>(max_pending_send_requests_));

  if (pending_send_requests_.size() > max_pending_send_requests_) {
    std::deque<PendingSendRequest*> discarded_requests(
        pending_send_requests_.begin() + max_pending_send_requests_,
        pending_send_requests_.end());
    pending_send_requests_.resize(max_pending_send_requests_);
    for (auto& discarded_request : discarded_requests) {
      discarded_request->callback.Run(
          MakeNetworkError(net::ERR_INSUFFICIENT_RESOURCES));
      delete discarded_request;
    }
  }
}

void UDPSocketImpl::ReceiveMore(uint32_t datagram_number) {
  if (!bound_ || datagram_number == 0)
    return;
  if (std::numeric_limits<size_t>::max() - remaining_recv_slots_ <
          datagram_number) {
    return;
  }

  remaining_recv_slots_ += datagram_number;

  if (!recvfrom_buffer_.get()) {
    DCHECK_EQ(datagram_number, remaining_recv_slots_);
    DoRecvFrom();
  }
}

void UDPSocketImpl::SendTo(NetAddressPtr dest_addr,
                           Array<uint8_t> data,
                           const Callback<void(NetworkErrorPtr)>& callback) {
  if (!bound_) {
    callback.Run(MakeNetworkError(net::ERR_FAILED));
    return;
  }

  if (sendto_buffer_.get()) {
    if (pending_send_requests_.size() >= max_pending_send_requests_) {
      callback.Run(MakeNetworkError(net::ERR_INSUFFICIENT_RESOURCES));
      return;
    }

    PendingSendRequest* request = new PendingSendRequest;
    request->addr = dest_addr.Pass();
    request->data = data.Pass();
    request->callback = callback;
    pending_send_requests_.push_back(request);
    return;
  }

  DCHECK_EQ(0u, pending_send_requests_.size());

  DoSendTo(dest_addr.Pass(), data.Pass(), callback);
}

void UDPSocketImpl::DoRecvFrom() {
  DCHECK(bound_);
  DCHECK(!recvfrom_buffer_.get());
  DCHECK_GT(remaining_recv_slots_, 0u);

  recvfrom_buffer_ = new net::IOBuffer(kMaxReadSize);

  // It is safe to use base::Unretained(this) because |socket_| is owned by this
  // object. If this object gets destroyed (and so does |socket_|), the callback
  // won't be called.
  int net_result = socket_.RecvFrom(
      recvfrom_buffer_.get(),
      kMaxReadSize,
      &recvfrom_address_,
      base::Bind(&UDPSocketImpl::OnRecvFromCompleted, base::Unretained(this)));
  if (net_result != net::ERR_IO_PENDING)
    OnRecvFromCompleted(net_result);
}

void UDPSocketImpl::DoSendTo(NetAddressPtr addr,
                             Array<uint8_t> data,
                             const Callback<void(NetworkErrorPtr)>& callback) {
  DCHECK(bound_);
  DCHECK(!sendto_buffer_.get());

  net::IPEndPoint ip_end_point = addr.To<net::IPEndPoint>();
  if (ip_end_point.GetFamily() == net::ADDRESS_FAMILY_UNSPECIFIED) {
    callback.Run(MakeNetworkError(net::ERR_ADDRESS_INVALID));
    return;
  }

  if (data.size() > kMaxWriteSize) {
    callback.Run(MakeNetworkError(net::ERR_INVALID_ARGUMENT));
    return;
  }
  sendto_buffer_ = new net::IOBufferWithSize(static_cast<int>(data.size()));
  if (data.size() > 0)
    memcpy(sendto_buffer_->data(), &data.storage()[0], data.size());

  // It is safe to use base::Unretained(this) because |socket_| is owned by this
  // object. If this object gets destroyed (and so does |socket_|), the callback
  // won't be called.
  int net_result = socket_.SendTo(sendto_buffer_.get(), sendto_buffer_->size(),
                                  ip_end_point,
                                  base::Bind(&UDPSocketImpl::OnSendToCompleted,
                                             base::Unretained(this), callback));
  if (net_result != net::ERR_IO_PENDING)
    OnSendToCompleted(callback, net_result);
}

void UDPSocketImpl::OnRecvFromCompleted(int net_result) {
  DCHECK(recvfrom_buffer_.get());

  NetAddressPtr net_address;
  Array<uint8_t> array;
  if (net_result >= 0) {
    net_address = NetAddress::From(recvfrom_address_);
    std::vector<uint8_t> data(net_result);
    if (net_result > 0)
      memcpy(&data[0], recvfrom_buffer_->data(), net_result);

    array.Swap(&data);
  }
  recvfrom_buffer_ = nullptr;

  client()->OnReceived(MakeNetworkError(net_result), net_address.Pass(),
                       array.Pass());

  DCHECK_GT(remaining_recv_slots_, 0u);
  remaining_recv_slots_--;
  if (remaining_recv_slots_ > 0)
    DoRecvFrom();
}

void UDPSocketImpl::OnSendToCompleted(
    const Callback<void(NetworkErrorPtr)>& callback,
    int net_result) {
  DCHECK(sendto_buffer_.get());

  sendto_buffer_ = nullptr;

  callback.Run(MakeNetworkError(net_result));

  if (pending_send_requests_.empty())
    return;

  scoped_ptr<PendingSendRequest> request(pending_send_requests_.front());
  pending_send_requests_.pop_front();

  DoSendTo(request->addr.Pass(), request->data.Pass(), request->callback);
}

}  // namespace mojo