// Copyright (c) 2012 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 "net/udp/udp_socket_libevent.h"

#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#include <sys/socket.h>

#include "base/callback.h"
#include "base/eintr_wrapper.h"
#include "base/logging.h"
#include "base/message_loop.h"
#include "base/metrics/stats_counters.h"
#include "base/rand_util.h"
#include "net/base/io_buffer.h"
#include "net/base/ip_endpoint.h"
#include "net/base/net_errors.h"
#include "net/base/net_log.h"
#include "net/base/net_util.h"
#include "net/udp/udp_net_log_parameters.h"
#if defined(OS_POSIX)
#include <netinet/in.h>
#endif

namespace {

static const int kBindRetries = 10;
static const int kPortStart = 1024;
static const int kPortEnd = 65535;

}  // namespace net

namespace net {

UDPSocketLibevent::UDPSocketLibevent(
    DatagramSocket::BindType bind_type,
    const RandIntCallback& rand_int_cb,
    net::NetLog* net_log,
    const net::NetLog::Source& source)
        : socket_(kInvalidSocket),
          socket_options_(0),
          bind_type_(bind_type),
          rand_int_cb_(rand_int_cb),
          read_watcher_(this),
          write_watcher_(this),
          read_buf_len_(0),
          recv_from_address_(NULL),
          write_buf_len_(0),
          net_log_(BoundNetLog::Make(net_log, NetLog::SOURCE_UDP_SOCKET)) {
  net_log_.BeginEvent(NetLog::TYPE_SOCKET_ALIVE,
                      source.ToEventParametersCallback());
  if (bind_type == DatagramSocket::RANDOM_BIND)
    DCHECK(!rand_int_cb.is_null());
}

UDPSocketLibevent::~UDPSocketLibevent() {
  Close();
  net_log_.EndEvent(NetLog::TYPE_SOCKET_ALIVE);
}

void UDPSocketLibevent::Close() {
  DCHECK(CalledOnValidThread());

  if (!is_connected())
    return;

  // Zero out any pending read/write callback state.
  read_buf_ = NULL;
  read_buf_len_ = 0;
  read_callback_.Reset();
  recv_from_address_ = NULL;
  write_buf_ = NULL;
  write_buf_len_ = 0;
  write_callback_.Reset();
  send_to_address_.reset();

  bool ok = read_socket_watcher_.StopWatchingFileDescriptor();
  DCHECK(ok);
  ok = write_socket_watcher_.StopWatchingFileDescriptor();
  DCHECK(ok);

  if (HANDLE_EINTR(close(socket_)) < 0)
    PLOG(ERROR) << "close";

  socket_ = kInvalidSocket;
}

int UDPSocketLibevent::GetPeerAddress(IPEndPoint* address) const {
  DCHECK(CalledOnValidThread());
  DCHECK(address);
  if (!is_connected())
    return ERR_SOCKET_NOT_CONNECTED;

  if (!remote_address_.get()) {
    SockaddrStorage storage;
    if (getpeername(socket_, storage.addr, &storage.addr_len))
      return MapSystemError(errno);
    scoped_ptr<IPEndPoint> address(new IPEndPoint());
    if (!address->FromSockAddr(storage.addr, storage.addr_len))
      return ERR_FAILED;
    remote_address_.reset(address.release());
  }

  *address = *remote_address_;
  return OK;
}

int UDPSocketLibevent::GetLocalAddress(IPEndPoint* address) const {
  DCHECK(CalledOnValidThread());
  DCHECK(address);
  if (!is_connected())
    return ERR_SOCKET_NOT_CONNECTED;

  if (!local_address_.get()) {
    SockaddrStorage storage;
    if (getsockname(socket_, storage.addr, &storage.addr_len))
      return MapSystemError(errno);
    scoped_ptr<IPEndPoint> address(new IPEndPoint());
    if (!address->FromSockAddr(storage.addr, storage.addr_len))
      return ERR_FAILED;
    local_address_.reset(address.release());
  }

  *address = *local_address_;
  return OK;
}

int UDPSocketLibevent::Read(IOBuffer* buf,
                            int buf_len,
                            const CompletionCallback& callback) {
  return RecvFrom(buf, buf_len, NULL, callback);
}

int UDPSocketLibevent::RecvFrom(IOBuffer* buf,
                                int buf_len,
                                IPEndPoint* address,
                                const CompletionCallback& callback) {
  DCHECK(CalledOnValidThread());
  DCHECK_NE(kInvalidSocket, socket_);
  DCHECK(read_callback_.is_null());
  DCHECK(!recv_from_address_);
  DCHECK(!callback.is_null());  // Synchronous operation not supported
  DCHECK_GT(buf_len, 0);

  int nread = InternalRecvFrom(buf, buf_len, address);
  if (nread != ERR_IO_PENDING)
    return nread;

  if (!MessageLoopForIO::current()->WatchFileDescriptor(
          socket_, true, MessageLoopForIO::WATCH_READ,
          &read_socket_watcher_, &read_watcher_)) {
    PLOG(ERROR) << "WatchFileDescriptor failed on read";
    int result = MapSystemError(errno);
    LogRead(result, NULL, 0, NULL);
    return result;
  }

  read_buf_ = buf;
  read_buf_len_ = buf_len;
  recv_from_address_ = address;
  read_callback_ = callback;
  return ERR_IO_PENDING;
}

int UDPSocketLibevent::Write(IOBuffer* buf,
                             int buf_len,
                             const CompletionCallback& callback) {
  return SendToOrWrite(buf, buf_len, NULL, callback);
}

int UDPSocketLibevent::SendTo(IOBuffer* buf,
                              int buf_len,
                              const IPEndPoint& address,
                              const CompletionCallback& callback) {
  return SendToOrWrite(buf, buf_len, &address, callback);
}

int UDPSocketLibevent::SendToOrWrite(IOBuffer* buf,
                                     int buf_len,
                                     const IPEndPoint* address,
                                     const CompletionCallback& callback) {
  DCHECK(CalledOnValidThread());
  DCHECK_NE(kInvalidSocket, socket_);
  DCHECK(write_callback_.is_null());
  DCHECK(!callback.is_null());  // Synchronous operation not supported
  DCHECK_GT(buf_len, 0);

  int result = InternalSendTo(buf, buf_len, address);
  if (result != ERR_IO_PENDING)
    return result;

  if (!MessageLoopForIO::current()->WatchFileDescriptor(
          socket_, true, MessageLoopForIO::WATCH_WRITE,
          &write_socket_watcher_, &write_watcher_)) {
    DVLOG(1) << "WatchFileDescriptor failed on write, errno " << errno;
    int result = MapSystemError(errno);
    LogWrite(result, NULL, NULL);
    return result;
  }

  write_buf_ = buf;
  write_buf_len_ = buf_len;
  DCHECK(!send_to_address_.get());
  if (address) {
    send_to_address_.reset(new IPEndPoint(*address));
  }
  write_callback_ = callback;
  return ERR_IO_PENDING;
}

int UDPSocketLibevent::Connect(const IPEndPoint& address) {
  net_log_.BeginEvent(NetLog::TYPE_UDP_CONNECT,
                      CreateNetLogUDPConnectCallback(&address));
  int rv = InternalConnect(address);
  net_log_.EndEventWithNetErrorCode(NetLog::TYPE_UDP_CONNECT, rv);
  return rv;
}

int UDPSocketLibevent::InternalConnect(const IPEndPoint& address) {
  DCHECK(CalledOnValidThread());
  DCHECK(!is_connected());
  DCHECK(!remote_address_.get());
  int rv = CreateSocket(address);
  if (rv < 0)
    return rv;

  if (bind_type_ == DatagramSocket::RANDOM_BIND)
    rv = RandomBind(address);
  // else connect() does the DatagramSocket::DEFAULT_BIND

  if (rv < 0)
    return rv;

  SockaddrStorage storage;
  if (!address.ToSockAddr(storage.addr, &storage.addr_len))
    return ERR_FAILED;

  rv = HANDLE_EINTR(connect(socket_, storage.addr, storage.addr_len));
  if (rv < 0)
    return MapSystemError(errno);

  remote_address_.reset(new IPEndPoint(address));
  return rv;
}

int UDPSocketLibevent::Bind(const IPEndPoint& address) {
  DCHECK(CalledOnValidThread());
  DCHECK(!is_connected());
  int rv = CreateSocket(address);
  if (rv < 0)
    return rv;
  rv = SetSocketOptions();
  if (rv < 0)
    return rv;
  rv = DoBind(address);
  if (rv < 0)
    return rv;
  local_address_.reset();
  return rv;
}

bool UDPSocketLibevent::SetReceiveBufferSize(int32 size) {
  DCHECK(CalledOnValidThread());
  int rv = setsockopt(socket_, SOL_SOCKET, SO_RCVBUF,
                      reinterpret_cast<const char*>(&size), sizeof(size));
  DCHECK(!rv) << "Could not set socket receive buffer size: " << errno;
  return rv == 0;
}

bool UDPSocketLibevent::SetSendBufferSize(int32 size) {
  DCHECK(CalledOnValidThread());
  int rv = setsockopt(socket_, SOL_SOCKET, SO_SNDBUF,
                      reinterpret_cast<const char*>(&size), sizeof(size));
  DCHECK(!rv) << "Could not set socket send buffer size: " << errno;
  return rv == 0;
}

void UDPSocketLibevent::AllowAddressReuse() {
  DCHECK(CalledOnValidThread());
  DCHECK(!is_connected());

  socket_options_ |= SOCKET_OPTION_REUSE_ADDRESS;
}

void UDPSocketLibevent::AllowBroadcast() {
  DCHECK(CalledOnValidThread());
  DCHECK(!is_connected());

  socket_options_ |= SOCKET_OPTION_BROADCAST;
}

void UDPSocketLibevent::ReadWatcher::OnFileCanReadWithoutBlocking(int) {
  if (!socket_->read_callback_.is_null())
    socket_->DidCompleteRead();
}

void UDPSocketLibevent::WriteWatcher::OnFileCanWriteWithoutBlocking(int) {
  if (!socket_->write_callback_.is_null())
    socket_->DidCompleteWrite();
}

void UDPSocketLibevent::DoReadCallback(int rv) {
  DCHECK_NE(rv, ERR_IO_PENDING);
  DCHECK(!read_callback_.is_null());

  // since Run may result in Read being called, clear read_callback_ up front.
  CompletionCallback c = read_callback_;
  read_callback_.Reset();
  c.Run(rv);
}

void UDPSocketLibevent::DoWriteCallback(int rv) {
  DCHECK_NE(rv, ERR_IO_PENDING);
  DCHECK(!write_callback_.is_null());

  // since Run may result in Write being called, clear write_callback_ up front.
  CompletionCallback c = write_callback_;
  write_callback_.Reset();
  c.Run(rv);
}

void UDPSocketLibevent::DidCompleteRead() {
  int result = InternalRecvFrom(read_buf_, read_buf_len_, recv_from_address_);
  if (result != ERR_IO_PENDING) {
    read_buf_ = NULL;
    read_buf_len_ = 0;
    recv_from_address_ = NULL;
    bool ok = read_socket_watcher_.StopWatchingFileDescriptor();
    DCHECK(ok);
    DoReadCallback(result);
  }
}

void UDPSocketLibevent::LogRead(int result,
                                const char* bytes,
                                socklen_t addr_len,
                                const sockaddr* addr) const {
  if (result < 0) {
    net_log_.AddEventWithNetErrorCode(NetLog::TYPE_UDP_RECEIVE_ERROR, result);
    return;
  }

  if (net_log_.IsLoggingAllEvents()) {
    DCHECK(addr_len > 0);
    DCHECK(addr);

    IPEndPoint address;
    bool is_address_valid = address.FromSockAddr(addr, addr_len);
    net_log_.AddEvent(
        NetLog::TYPE_UDP_BYTES_RECEIVED,
        CreateNetLogUDPDataTranferCallback(
            result, bytes,
            is_address_valid ? &address : NULL));
  }

  base::StatsCounter read_bytes("udp.read_bytes");
  read_bytes.Add(result);
}

int UDPSocketLibevent::CreateSocket(const IPEndPoint& address) {
  socket_ = socket(address.GetFamily(), SOCK_DGRAM, 0);
  if (socket_ == kInvalidSocket)
    return MapSystemError(errno);
  if (SetNonBlocking(socket_)) {
    const int err = MapSystemError(errno);
    Close();
    return err;
  }
  return OK;
}

void UDPSocketLibevent::DidCompleteWrite() {
  int result = InternalSendTo(write_buf_, write_buf_len_,
                              send_to_address_.get());

  if (result != ERR_IO_PENDING) {
    write_buf_ = NULL;
    write_buf_len_ = 0;
    send_to_address_.reset();
    write_socket_watcher_.StopWatchingFileDescriptor();
    DoWriteCallback(result);
  }
}

void UDPSocketLibevent::LogWrite(int result,
                                 const char* bytes,
                                 const IPEndPoint* address) const {
  if (result < 0) {
    net_log_.AddEventWithNetErrorCode(NetLog::TYPE_UDP_SEND_ERROR, result);
    return;
  }

  if (net_log_.IsLoggingAllEvents()) {
    net_log_.AddEvent(
        NetLog::TYPE_UDP_BYTES_SENT,
        CreateNetLogUDPDataTranferCallback(result, bytes, address));
  }

  base::StatsCounter write_bytes("udp.write_bytes");
  write_bytes.Add(result);
}

int UDPSocketLibevent::InternalRecvFrom(IOBuffer* buf, int buf_len,
                                        IPEndPoint* address) {
  int bytes_transferred;
  int flags = 0;

  SockaddrStorage storage;

  bytes_transferred =
      HANDLE_EINTR(recvfrom(socket_,
                            buf->data(),
                            buf_len,
                            flags,
                            storage.addr,
                            &storage.addr_len));
  int result;
  if (bytes_transferred >= 0) {
    result = bytes_transferred;
    if (address && !address->FromSockAddr(storage.addr, storage.addr_len))
      result = ERR_FAILED;
  } else {
    result = MapSystemError(errno);
  }
  if (result != ERR_IO_PENDING)
    LogRead(result, buf->data(), storage.addr_len, storage.addr);
  return result;
}

int UDPSocketLibevent::InternalSendTo(IOBuffer* buf, int buf_len,
                                      const IPEndPoint* address) {
  SockaddrStorage storage;
  struct sockaddr* addr = storage.addr;
  if (!address) {
    addr = NULL;
    storage.addr_len = 0;
  } else {
    if (!address->ToSockAddr(storage.addr, &storage.addr_len)) {
      int result = ERR_FAILED;
      LogWrite(result, NULL, NULL);
      return result;
    }
  }

  int result = HANDLE_EINTR(sendto(socket_,
                            buf->data(),
                            buf_len,
                            0,
                            addr,
                            storage.addr_len));
  if (result < 0)
    result = MapSystemError(errno);
  if (result != ERR_IO_PENDING)
    LogWrite(result, buf->data(), address);
  return result;
}

int UDPSocketLibevent::SetSocketOptions() {
  int true_value = 1;
  if (socket_options_ & SOCKET_OPTION_REUSE_ADDRESS) {
    int rv = setsockopt(socket_, SOL_SOCKET, SO_REUSEADDR, &true_value,
                        sizeof(true_value));
    if (rv < 0)
      return MapSystemError(errno);
  }
  if (socket_options_ & SOCKET_OPTION_BROADCAST) {
    int rv;
#if defined(OS_MACOSX)
    // SO_REUSEPORT on OSX permits multiple processes to each receive
    // UDP multicast or broadcast datagrams destined for the bound
    // port.
    rv = setsockopt(socket_, SOL_SOCKET, SO_REUSEPORT, &true_value,
                    sizeof(true_value));
    if (rv < 0)
      return MapSystemError(errno);
#endif  // defined(OS_MACOSX)
    rv = setsockopt(socket_, SOL_SOCKET, SO_BROADCAST, &true_value,
                    sizeof(true_value));
    if (rv < 0)
      return MapSystemError(errno);
  }
  return OK;
}

int UDPSocketLibevent::DoBind(const IPEndPoint& address) {
  SockaddrStorage storage;
  if (!address.ToSockAddr(storage.addr, &storage.addr_len))
    return ERR_UNEXPECTED;
  int rv = bind(socket_, storage.addr, storage.addr_len);
  return rv < 0 ? MapSystemError(errno) : rv;
}

int UDPSocketLibevent::RandomBind(const IPEndPoint& address) {
  DCHECK(bind_type_ == DatagramSocket::RANDOM_BIND && !rand_int_cb_.is_null());

  // Construct IPAddressNumber of appropriate size (IPv4 or IPv6) of 0s.
  IPAddressNumber ip(address.address().size());

  for (int i = 0; i < kBindRetries; ++i) {
    int rv = DoBind(IPEndPoint(ip, rand_int_cb_.Run(kPortStart, kPortEnd)));
    if (rv == OK || rv != ERR_ADDRESS_IN_USE)
      return rv;
  }
  return DoBind(IPEndPoint(ip, 0));
}

}  // namespace net