Update the docs for the new network APIs

[platform/upstream/glib.git] / gio / gsocket.c

/* GIO - GLib Input, Output and Streaming Library
 *
 * Copyright (C) 2008 Christian Kellner, Samuel Cormier-Iijima
 * Copyright © 2009 Codethink Limited
 * Copyright © 2009 Red Hat, Inc
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General
 * Public License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * Authors: Christian Kellner <gicmo@gnome.org>
 *          Samuel Cormier-Iijima <sciyoshi@gmail.com>
 *          Ryan Lortie <desrt@desrt.ca>
 *          Alexander Larsson <alexl@redhat.com>
 */

#include "config.h"

#include <errno.h>
#include <string.h>
#include <stdlib.h>

#ifndef G_OS_WIN32
# include <netinet/in.h>
# include <arpa/inet.h>
# include <netdb.h>
# include <fcntl.h>
# include <unistd.h>
# include <sys/types.h>
#else
# include <winsock2.h>
# include <mswsock.h>
#endif

#include "gsocket.h"
#include "gcancellable.h"
#include "gioenumtypes.h"
#include "ginitable.h"
#include "gasynchelper.h"
#include "gioerror.h"
#include "gioenums.h"
#include "gioerror.h"
#include "glibintl.h"

#include "gioalias.h"

/**
 * SECTION:gsocket
 * @short_description: Low-level socket object
 * @include: gio/gio.h
 * @see_also: #GInitable
 *
 * A #GSocket is a low-level networking primitive. It is a more or less
 * direct mapping of the BSD socket API in a portable GObject based API.
 * It supports both the unix socket implementations and winsock2 on Windows.
 *
 * #GSocket is the platform independent base upon which the higher level
 * network primitives are based. Applications are not typically meant to
 * use it directly, but rather through classes like #GSocketClient,
 * #GSocketService and #GSocketConnection. However there may be cases where
 * direct use of #GSocket is useful.
 *
 * #GSocket implements the #GInitable interface, so if it is manually constructed
 * by e.g. g_object_new() you must call g_initable_init() and check the
 * results before using the object. This is done automatically in
 * g_socket_new() and g_socket_new_from_fd(), so these functions can return
 * %NULL.
 *
 * Sockets operate in two general modes, blocking or non-blocking. When
 * in blocking mode all operations block until the requested operation
 * is finished or there is an error. In non-blocking mode all calls that
 * would block return immediately with a %G_IO_ERROR_WOULD_BLOCK error.
 * To know when a call would successfully run you can call g_socket_condition_check(),
 * or g_socket_condition_wait(). You can also use g_socket_create_source() and
 * attach it to a #GMainContext to get callbacks when I/O is possible.
 * Note that all sockets are always set to non blocking mode in the system, and
 * blocking mode is emulated in GSocket.
 *
 * When working in non-blocking mode applications should always be able to
 * handle getting a %G_IO_ERROR_WOULD_BLOCK error even when some other
 * function said that I/O was possible. This can easily happen in case
 * of a race condition in the application, but it can also happen for other
 * reasons. For instance, on Windows a socket is always seen as writable
 * until a write returns %G_IO_ERROR_WOULD_BLOCK.
 *
 * #GSocket<!-- -->s can be either connection oriented or datagram based.
 * For connection oriented types you must first establish a connection by
 * either connecting to an address or accepting a connection from another
 * address. For connectionless socket types the target/source address is
 * specified or received in each I/O operation.
 *
 * All socket file descriptors are set to be close-on-exec.
 *
 * Since: 2.22
 **/

static void     g_socket_initable_iface_init (GInitableIface  *iface);
static gboolean g_socket_initable_init       (GInitable       *initable,
                                              GCancellable    *cancellable,
                                              GError         **error);

G_DEFINE_TYPE_WITH_CODE (GSocket, g_socket, G_TYPE_OBJECT,
                         G_IMPLEMENT_INTERFACE (G_TYPE_INITABLE,
                                                g_socket_initable_iface_init));

enum
{
  PROP_0,
  PROP_FAMILY,
  PROP_TYPE,
  PROP_PROTOCOL,
  PROP_FD,
  PROP_BLOCKING,
  PROP_LISTEN_BACKLOG,
  PROP_KEEPALIVE,
  PROP_LOCAL_ADDRESS,
  PROP_REMOTE_ADDRESS
};

struct _GSocketPrivate
{
  GSocketFamily   family;
  GSocketType     type;
  gint            protocol;
  gint            fd;
  gint            listen_backlog;
  GError         *construct_error;
  GSocketAddress *local_address;
  GSocketAddress *remote_address;
  guint           inited : 1;
  guint           blocking : 1;
  guint           keepalive : 1;
  guint           closed : 1;
#ifdef G_OS_WIN32
  WSAEVENT        event;
  int             current_events;
  int             current_errors;
  int             selected_events;
  GList          *requested_conditions; /* list of requested GIOCondition * */
#endif
};

static int
get_socket_errno (void)
{
#ifndef G_OS_WIN32
  return errno;
#else
  return WSAGetLastError ();
#endif
}

static GIOErrorEnum
socket_io_error_from_errno (int err)
{
#ifndef G_OS_WIN32
  return g_io_error_from_errno (err);
#else
  switch (err)
    {
    case WSAEADDRINUSE:
      return G_IO_ERROR_ADDRESS_IN_USE;
    case WSAEWOULDBLOCK:
      return G_IO_ERROR_WOULD_BLOCK;
    case WSAEACCES:
      return G_IO_ERROR_PERMISSION_DENIED;
    case WSA_INVALID_HANDLE:
    case WSA_INVALID_PARAMETER:
    case WSAEBADF:
    case WSAENOTSOCK:
      return G_IO_ERROR_INVALID_ARGUMENT;
    case WSAEPROTONOSUPPORT:
      return G_IO_ERROR_NOT_SUPPORTED;
    case WSAECANCELLED:
      return G_IO_ERROR_CANCELLED;
    case WSAESOCKTNOSUPPORT:
    case WSAEOPNOTSUPP:
    case WSAEPFNOSUPPORT:
    case WSAEAFNOSUPPORT:
      return G_IO_ERROR_NOT_SUPPORTED;
    default:
      return G_IO_ERROR_FAILED;
    }
#endif
}

static const char *
socket_strerror (int err)
{
#ifndef G_OS_WIN32
  return g_strerror (err);
#else
  static GStaticPrivate msg_private = G_STATIC_PRIVATE_INIT;
  char *buf, *msg;

  buf = g_static_private_get (&msg_private);
  if (!buf)
    {
      buf = g_new (gchar, 128);
      g_static_private_set (&msg_private, buf, g_free);
    }

  msg = g_win32_error_message (err);
  strncpy (buf, msg, 128);
  g_free (msg);
  return buf;
#endif
}

#ifdef G_OS_WIN32
#define win32_unset_event_mask(_socket, _mask) _win32_unset_event_mask (_socket, _mask)
static void
_win32_unset_event_mask (GSocket *socket, int mask)
{
  socket->priv->current_events &= ~mask;
  socket->priv->current_errors &= ~mask;
}
#else
#define win32_unset_event_mask(_socket, _mask)
#endif

static void
set_fd_nonblocking (int fd)
{
#ifndef G_OS_WIN32
  glong arg;
#else
  gulong arg;
#endif

#ifndef G_OS_WIN32
  if ((arg = fcntl (fd, F_GETFL, NULL)) < 0)
    {
      g_warning ("Error getting socket status flags: %s", socket_strerror (errno));
      arg = 0;
    }

  arg = arg | O_NONBLOCK;

  if (fcntl (fd, F_SETFL, arg) < 0)
      g_warning ("Error setting socket status flags: %s", socket_strerror (errno));
#else
  arg = TRUE;

  if (ioctlsocket (fd, FIONBIO, &arg) == SOCKET_ERROR)
    {
      int errsv = get_socket_errno ();
      g_warning ("Error setting socket status flags: %s", socket_strerror (errsv));
    }
#endif
}

static gboolean
check_socket (GSocket *socket,
              GError **error)
{
  if (!socket->priv->inited)
    {
      g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_INITIALIZED,
                   _("Invalid socket, not initialized"));
      return FALSE;
    }

  if (socket->priv->construct_error)
    {
      g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_INITIALIZED,
                   _("Invalid socket, initialization failed due to: %s"),
                   socket->priv->construct_error->message);
      return FALSE;
    }

  if (socket->priv->closed)
    {
      g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_CLOSED,
                           _("Socket is already closed"));
      return FALSE;
    }
  return TRUE;
}

static void
g_socket_details_from_fd (GSocket *socket)
{
  struct sockaddr_storage address;
  gint fd;
  guint addrlen;
  guint optlen;
  int value;
  int errsv;
#ifdef G_OS_WIN32
  BOOL bool_val;
#else
  int bool_val;
#endif

  fd = socket->priv->fd;
  optlen = sizeof value;
  if (getsockopt (fd, SOL_SOCKET, SO_TYPE, (void *)&value, &optlen) != 0)
    {
      errsv = get_socket_errno ();

      switch (errsv)
        {
#ifdef ENOTSOCK
         case ENOTSOCK:
#endif
#ifdef WSAENOTSOCK
         case WSAENOTSOCK:
#endif
         case EBADF:
          /* programmer error */
          g_error ("creating GSocket from fd %d: %s\n",
                   fd, socket_strerror (errsv));
         default:
           break;
        }

      goto err;
    }

  g_assert (optlen == sizeof value);
  switch (value)
    {
     case SOCK_STREAM:
      socket->priv->type = G_SOCKET_TYPE_STREAM;
      break;

     case SOCK_DGRAM:
      socket->priv->type = G_SOCKET_TYPE_DATAGRAM;
      break;

     case SOCK_SEQPACKET:
      socket->priv->type = G_SOCKET_TYPE_SEQPACKET;
      break;

     default:
      socket->priv->type = G_SOCKET_TYPE_INVALID;
      break;
    }

  addrlen = sizeof address;
  if (getsockname (fd, (struct sockaddr *) &address, &addrlen) != 0)
    {
      errsv = get_socket_errno ();
      goto err;
    }

  g_assert (G_STRUCT_OFFSET (struct sockaddr, sa_family) +
            sizeof address.ss_family <= addrlen);
  switch (address.ss_family)
    {
     case G_SOCKET_FAMILY_IPV4:
     case G_SOCKET_FAMILY_IPV6:
     case G_SOCKET_FAMILY_UNIX:
      socket->priv->family = address.ss_family;
      break;

     default:
      socket->priv->family = G_SOCKET_FAMILY_INVALID;
      break;
    }

  if (socket->priv->family != G_SOCKET_FAMILY_INVALID)
    {
      socket->priv->local_address =
        g_socket_address_new_from_native (&address, addrlen);

      addrlen = sizeof address;
      if (getpeername (fd, (struct sockaddr *) &address, &addrlen) >= 0)
        socket->priv->remote_address =
          g_socket_address_new_from_native (&address, addrlen);
    }

  optlen = sizeof bool_val;
  if (getsockopt (fd, SOL_SOCKET, SO_KEEPALIVE,
                  (void *)&bool_val, &optlen) == 0)
    {
      g_assert (optlen == sizeof bool_val);
      socket->priv->keepalive = !!bool_val;
    }
  else
    {
      /* Can't read, maybe not supported, assume FALSE */
      socket->priv->keepalive = FALSE;
    }

  return;

 err:
  g_set_error (&socket->priv->construct_error, G_IO_ERROR,
               socket_io_error_from_errno (errsv),
               _("creating GSocket from fd: %s"),
               socket_strerror (errsv));
}

static char *
get_protocol_name (int protocol_id)
{
  struct protoent *protoent;
#ifdef HAVE_GETPROTOBYNUMBER_R
  char buffer[1024];
  struct protoent my_protoent;
#endif

  if (protocol_id == 0)
    return NULL;

  if (protocol_id == -1)
    return g_strdup ("unknown");

#ifdef HAVE_GETPROTOBYNUMBER_R
  protoent = NULL;
  getprotobynumber_r (protocol_id,
                      &my_protoent, buffer, sizeof (buffer),
                      &protoent);
#else
  protoent = getprotobynumber (protocol_id);
#endif

  if (protoent == NULL)
    return g_strdup_printf ("proto-%d", protocol_id);

  return g_strdup (protoent->p_name);
}

/**
 * g_socket_protocol_id_lookup_by_name:
 * @protocol_name: The name of a protocol, or %NULL
 *
 * Tries to look up the protocol id for a given
 * protocol name. If the protocol name is not known
 * on this system it returns -1.
 *
 * If @protocol_name is %NULL (default protocol) then
 * 0 is returned.
 *
 * Returns: a protocol id, or -1 if unknown
 *
 * Since: 2.22
 **/
gint
g_socket_protocol_id_lookup_by_name (const char *protocol_name)
{
  struct protoent *protoent;
  int protocol = 0;
#ifdef HAVE_GETPROTOBYNAME_R
  char buffer[1024];
  struct protoent my_protoent;
#endif

  if (!protocol_name)
    return 0;

#ifdef HAVE_GETPROTOBYNAME_R
  protoent = NULL;
  getprotobyname_r (protocol_name,
                    &my_protoent, buffer, sizeof (buffer),
                    &protoent);
#else
  protoent = getprotobyname (protocol_name);
#endif

  if (protoent == NULL)
    {
      if (g_str_has_prefix (protocol_name, "proto-"))
        return atoi (protocol_name + strlen ("proto-"));
      return -1;
    }
  protocol = protoent->p_proto;

  return protocol;
}

static gint
g_socket_create_socket (GSocketFamily   family,
                        GSocketType     type,
                        int             protocol_id,
                        GError        **error)
{
  gint native_type;
  gint fd;

  switch (type)
    {
     case G_SOCKET_TYPE_STREAM:
      native_type = SOCK_STREAM;
      break;

     case G_SOCKET_TYPE_DATAGRAM:
      native_type = SOCK_DGRAM;
      break;

     case G_SOCKET_TYPE_SEQPACKET:
      native_type = SOCK_SEQPACKET;
      break;

     default:
      g_assert_not_reached ();
    }

  if (protocol_id == -1)
    {
      g_set_error (error, G_IO_ERROR, G_IO_ERROR_INVALID_ARGUMENT,
                   _("Unable to create socket: %s"), _("Unknown protocol was specified"));
      return -1;
    }

#ifdef SOCK_CLOEXEC
  native_type |= SOCK_CLOEXEC;
#endif
  fd = socket (family, native_type, protocol_id);

  if (fd < 0)
    {
      int errsv = get_socket_errno ();

      g_set_error (error, G_IO_ERROR, socket_io_error_from_errno (errsv),
                   _("Unable to create socket: %s"), socket_strerror (errsv));
    }

#ifndef G_OS_WIN32
  {
    int flags;

    /* We always want to set close-on-exec to protect users. If you
       need to so some weird inheritance to exec you can re-enable this
       using lower level hacks with g_socket_get_fd(). */
    flags = fcntl (fd, F_GETFD, 0);
    if (flags != -1 &&
        (flags & FD_CLOEXEC) == 0)
      {
        flags |= FD_CLOEXEC;
        fcntl (fd, F_SETFD, flags);
      }
  }
#endif

  return fd;
}

static void
g_socket_constructed (GObject *object)
{
  GSocket *socket = G_SOCKET (object);

  if (socket->priv->fd >= 0)
    /* create socket->priv info from the fd */
    g_socket_details_from_fd (socket);

  else
    /* create the fd from socket->priv info */
    socket->priv->fd = g_socket_create_socket (socket->priv->family,
                                               socket->priv->type,
                                               socket->priv->protocol,
                                               &socket->priv->construct_error);

  /* Always use native nonblocking sockets, as
     windows sets sockets to nonblocking automatically
     in certain operations. This way we make things work
     the same on all platforms */
  if (socket->priv->fd != -1)
    set_fd_nonblocking (socket->priv->fd);
}

static void
g_socket_get_property (GObject    *object,
                       guint       prop_id,
                       GValue     *value,
                       GParamSpec *pspec)
{
  GSocket *socket = G_SOCKET (object);

  switch (prop_id)
    {
      case PROP_FAMILY:
        g_value_set_enum (value, socket->priv->family);
        break;

      case PROP_TYPE:
        g_value_set_enum (value, socket->priv->type);
        break;

      case PROP_PROTOCOL:
        g_value_set_int (value, socket->priv->protocol);
        break;

      case PROP_FD:
        g_value_set_int (value, socket->priv->fd);
        break;

      case PROP_BLOCKING:
        g_value_set_boolean (value, socket->priv->blocking);
        break;

      case PROP_LISTEN_BACKLOG:
        g_value_set_int (value, socket->priv->listen_backlog);
        break;

      case PROP_KEEPALIVE:
        g_value_set_boolean (value, socket->priv->keepalive);
        break;

      case PROP_LOCAL_ADDRESS:
        g_value_set_object (value, socket->priv->local_address);
        break;

      case PROP_REMOTE_ADDRESS:
        g_value_set_object (value, socket->priv->remote_address);
        break;

      default:
        G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
    }
}

static void
g_socket_set_property (GObject      *object,
                       guint         prop_id,
                       const GValue *value,
                       GParamSpec   *pspec)
{
  GSocket *socket = G_SOCKET (object);

  switch (prop_id)
    {
      case PROP_FAMILY:
        socket->priv->family = g_value_get_enum (value);
        break;

      case PROP_TYPE:
        socket->priv->type = g_value_get_enum (value);
        break;

      case PROP_PROTOCOL:
        socket->priv->protocol = g_value_get_int (value);
        break;

      case PROP_FD:
        socket->priv->fd = g_value_get_int (value);
        break;

      case PROP_BLOCKING:
        g_socket_set_blocking (socket, g_value_get_boolean (value));
        break;

      case PROP_LISTEN_BACKLOG:
        g_socket_set_listen_backlog (socket, g_value_get_int (value));
        break;

      case PROP_KEEPALIVE:
        g_socket_set_keepalive (socket, g_value_get_boolean (value));
        break;

      default:
        G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
    }
}

static void
g_socket_finalize (GObject *object)
{
  GSocket *socket = G_SOCKET (object);

  g_clear_error (&socket->priv->construct_error);

  if (socket->priv->fd != -1 &&
      !socket->priv->closed)
    g_socket_close (socket, NULL);

#ifdef G_OS_WIN32
  g_assert (socket->priv->requested_conditions == NULL);
#endif

  if (G_OBJECT_CLASS (g_socket_parent_class)->finalize)
    (*G_OBJECT_CLASS (g_socket_parent_class)->finalize) (object);
}

static void
g_socket_dispose (GObject *object)
{
  GSocket *socket = G_SOCKET (object);

  if (socket->priv->local_address)
    {
      g_object_unref (socket->priv->local_address);
      socket->priv->local_address = NULL;
    }

  if (socket->priv->remote_address)
    {
      g_object_unref (socket->priv->remote_address);
      socket->priv->remote_address = NULL;
    }

  if (G_OBJECT_CLASS (g_socket_parent_class)->dispose)
    (*G_OBJECT_CLASS (g_socket_parent_class)->dispose) (object);
}

static void
g_socket_class_init (GSocketClass *klass)
{
  GObjectClass *gobject_class G_GNUC_UNUSED = G_OBJECT_CLASS (klass);
  volatile GType type;

  /* Make sure winsock has been initialized */
  type = g_inet_address_get_type ();

  g_type_class_add_private (klass, sizeof (GSocketPrivate));

  gobject_class->finalize = g_socket_finalize;
  gobject_class->dispose = g_socket_dispose;
  gobject_class->constructed = g_socket_constructed;
  gobject_class->set_property = g_socket_set_property;
  gobject_class->get_property = g_socket_get_property;

  g_object_class_install_property (gobject_class, PROP_FAMILY,
                                   g_param_spec_enum ("family",
                                                      P_("Socket family"),
                                                      P_("The sockets address family"),
                                                      G_TYPE_SOCKET_FAMILY,
                                                      G_SOCKET_FAMILY_INVALID,
                                                      G_PARAM_CONSTRUCT_ONLY | G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

  g_object_class_install_property (gobject_class, PROP_TYPE,
                                   g_param_spec_enum ("type",
                                                      P_("Socket type"),
                                                      P_("The sockets type"),
                                                      G_TYPE_SOCKET_TYPE,
                                                      G_SOCKET_TYPE_STREAM,
                                                      G_PARAM_CONSTRUCT_ONLY | G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

  g_object_class_install_property (gobject_class, PROP_PROTOCOL,
                                   g_param_spec_int ("protocol",
                                                     P_("Socket protocol"),
                                                     P_("The id of the protocol to use, or -1 for unknown"),
                                                     G_MININT,
                                                     G_MAXINT,
                                                     -1,
                                                     G_PARAM_CONSTRUCT_ONLY | G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

  g_object_class_install_property (gobject_class, PROP_FD,
                                   g_param_spec_int ("fd",
                                                     P_("File descriptor"),
                                                     P_("The sockets file descriptor"),
                                                     G_MININT,
                                                     G_MAXINT,
                                                     -1,
                                                     G_PARAM_CONSTRUCT_ONLY | G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

  g_object_class_install_property (gobject_class, PROP_BLOCKING,
                                   g_param_spec_boolean ("blocking",
                                                         P_("blocking"),
                                                         P_("Whether or not I/O on this socket is blocking"),
                                                         TRUE,
                                                         G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

  g_object_class_install_property (gobject_class, PROP_LISTEN_BACKLOG,
                                   g_param_spec_int ("listen-backlog",
                                                     P_("Listen backlog"),
                                                     P_("outstanding connections in the listen queue"),
                                                     0,
                                                     SOMAXCONN,
                                                     10,
                                                     G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

  g_object_class_install_property (gobject_class, PROP_KEEPALIVE,
                                   g_param_spec_boolean ("keepalive",
                                                         P_("Keep connection alive"),
                                                         P_("Keep connection alive by sending periodic pings"),
                                                         FALSE,
                                                         G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));

  g_object_class_install_property (gobject_class, PROP_LOCAL_ADDRESS,
                                   g_param_spec_object ("local-address",
                                                        P_("Local address"),
                                                        P_("The local address the socket is bound to"),
                                                        G_TYPE_SOCKET_ADDRESS,
                                                        G_PARAM_READABLE | G_PARAM_STATIC_STRINGS));

  g_object_class_install_property (gobject_class, PROP_REMOTE_ADDRESS,
                                   g_param_spec_object ("remote-address",
                                                        P_("Remote address"),
                                                        P_("The remote address the socket is connected to"),
                                                        G_TYPE_SOCKET_ADDRESS,
                                                        G_PARAM_READABLE | G_PARAM_STATIC_STRINGS));
}

static void
g_socket_initable_iface_init (GInitableIface *iface)
{
  iface->init = g_socket_initable_init;
}

static void
g_socket_init (GSocket *socket)
{
  socket->priv = G_TYPE_INSTANCE_GET_PRIVATE (socket, G_TYPE_SOCKET, GSocketPrivate);

  socket->priv->fd = -1;
  socket->priv->blocking = TRUE;
  socket->priv->listen_backlog = 10;
  socket->priv->construct_error = NULL;
  socket->priv->remote_address = NULL;
  socket->priv->local_address = NULL;
#ifdef G_OS_WIN32
  socket->priv->event = WSA_INVALID_EVENT;
#endif
}

static gboolean
g_socket_initable_init (GInitable *initable,
                        GCancellable *cancellable,
                        GError  **error)
{
  GSocket  *socket;

  g_return_val_if_fail (G_IS_SOCKET (initable), FALSE);

  socket = G_SOCKET (initable);

  if (cancellable != NULL)
    {
      g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
                   _("Cancellable initialization not supported"));
      return FALSE;
    }

  socket->priv->inited = TRUE;

  if (socket->priv->construct_error)
    {
      if (error)
        *error = g_error_copy (socket->priv->construct_error);
      return FALSE;
    }


  return TRUE;
}

/**
 * g_socket_new:
 * @family: the socket family to use, e.g. %G_SOCKET_FAMILY_IPV4.
 * @type: the socket type to use.
 * @protocol_id: the id of the protocol to use, or 0 for default.
 * @error: #GError for error reporting, or %NULL to ignore.
 *
 * Creates a new #GSocket with the defined family, type and protocol.
 * If @protocol is %NULL the default protocol type for the family and
 * type is used.
 *
 * The @protocol is a family and type specific int that specifies what
 * kind of protocol to use. Many families only support one protocol,
 * and use 0 for this, others support several and using 0 means
 * to use the default protocol for the family and type. To use
 * other protocol, you can use g_socket_protocol_id_lookup_by_name()
 * to look up the protocol by name, or if you known the system specific
 * protocol id you can use that.
 *
 * Returns: a #GSocket or %NULL on error.
 *     Free the returned object with g_object_unref().
 *
 * Since: 2.22
 **/
GSocket *
g_socket_new (GSocketFamily family,
              GSocketType type,
              int protocol_id,
              GError **error)
{
  return G_SOCKET (g_initable_new (G_TYPE_SOCKET,
                                   NULL, error,
                                   "family", family,
                                   "type", type,
                                   "protocol", protocol_id,
                                   NULL));
}

/**
 * g_socket_new_from_fd:
 * @fd: a native socket file descriptor.
 * @error: #GError for error reporting, or %NULL to ignore.
 *
 * Creates a new #GSocket from a native file descriptor
 * or winsock SOCKET handle.
 *
 * This reads all the settings from the file descriptor so that
 * all properties should work. Note that the file descriptor
 * will be set to non-blocking mode, independent on the blocking
 * mode of the #GSocket.
 *
 * Returns: a #GSocket or %NULL on error.
 *     Free the returned object with g_object_unref().
 *
 * Since: 2.22
 **/
GSocket *
g_socket_new_from_fd (gint fd,
                      GError **error)
{
  return G_SOCKET (g_initable_new (G_TYPE_SOCKET,
                                   NULL, error,
                                   "fd", fd,
                                   NULL));
}

/**
 * g_socket_set_blocking:
 * @socket: a #GSocket.
 * @blocking: Whether to use blocking I/O or not.
 *
 * Sets the blocking mode of the socket. In blocking mode
 * all operations block until they succeed or there is an error. In
 * non-blocking mode all functions return results immediately or
 * with a %G_IO_ERROR_WOULD_BLOCK error.
 *
 * All sockets are created in blocking mode. However, note that the
 * platform level socket is always non-blocking, and blocking mode
 * is a GSocket level feature.
 *
 * Since: 2.22
 **/
void
g_socket_set_blocking (GSocket  *socket,
                       gboolean  blocking)
{
  g_return_if_fail (G_IS_SOCKET (socket));

  blocking = !!blocking;

  if (socket->priv->blocking == blocking)
    return;

  socket->priv->blocking = blocking;
  g_object_notify (G_OBJECT (socket), "blocking");
}

/**
 * g_socket_get_blocking:
 * @socket: a #GSocket.
 *
 * Gets the blocking mode of the socket. For details on blocking I/O,
 * see g_socket_set_blocking().
 *
 * Returns: %TRUE if blocking I/O is used, %FALSE otherwise.
 *
 * Since: 2.22
 **/
gboolean
g_socket_get_blocking (GSocket *socket)
{
  g_return_val_if_fail (G_IS_SOCKET (socket), FALSE);

  return socket->priv->blocking;
}

/**
 * g_socket_set_keepalive:
 * @socket: a #GSocket.
 * @keepalive: Whether to use try to keep the connection alive or not.
 *
 * Setting @keepalive to %TRUE enables the sending of periodic ping requests
 * on idle connections in order to keep the connection alive. This is only
 * useful for connection oriented sockets. The exact period used between
 * each ping is system and protocol dependent.
 *
 * Sending keepalive requests like this has a few disadvantages. For instance,
 * it uses more network bandwidth, and it makes your application more sensitive
 * to temporary outages in the network (i.e. if a cable is pulled your otherwise
 * idle connection could be terminated, whereas otherwise it would survive unless
 * actually used before the cable was reinserted). However, it is sometimes
 * useful to ensure that connections are eventually terminated if e.g. the
 * remote side is disconnected, so as to avoid leaking resources forever.
 *
 * Since: 2.22
 **/
void
g_socket_set_keepalive (GSocket *socket,
                        gboolean keepalive)
{
  int value;

  g_return_if_fail (G_IS_SOCKET (socket));

  keepalive = !!keepalive;
  if (socket->priv->keepalive == keepalive)
    return;

  value = (gint) keepalive;
  if (setsockopt (socket->priv->fd, SOL_SOCKET, SO_KEEPALIVE,
                  (gpointer) &value, sizeof (value)) < 0)
    {
      int errsv = get_socket_errno ();
      g_warning ("error setting keepalive: %s", socket_strerror (errsv));
      return;
    }

  socket->priv->keepalive = keepalive;
  g_object_notify (G_OBJECT (socket), "keepalive");
}

/**
 * g_socket_get_keepalive:
 * @socket: a #GSocket.
 *
 * Gets the keepalive mode of the socket. For details on this,
 * see g_socket_set_keepalive().
 *
 * Returns: %TRUE if keepalive is active, %FALSE otherwise.
 *
 * Since: 2.22
 **/
gboolean
g_socket_get_keepalive (GSocket *socket)
{
  g_return_val_if_fail (G_IS_SOCKET (socket), FALSE);

  return socket->priv->keepalive;
}

/**
 * g_socket_get_listen_backlog:
 * @socket: a #GSocket.
 *
 * Gets the listen backlog setting of the socket. For details on this,
 * see g_socket_set_listen_backlog().
 *
 * Returns: the maximum number of pending connections.
 *
 * Since: 2.22
 **/
gint
g_socket_get_listen_backlog  (GSocket                 *socket)
{
  g_return_val_if_fail (G_IS_SOCKET (socket), 0);

  return socket->priv->listen_backlog;
}

/**
 * g_socket_set_listen_backlog:
 * @socket: a #GSocket.
 * @backlog: the maximum number of pending connections.
 *
 * Sets the maximum number of outstanding connections allowed
 * when listening on this socket. If more clients than this are
 * connecting to the socket and the application is not handling them
 * on time then the new connections will be refused.
 *
 * Since: 2.22
 **/
void
g_socket_set_listen_backlog (GSocket *socket,
                             gint backlog)
{
  g_return_if_fail (G_IS_SOCKET (socket));

  if (backlog != socket->priv->listen_backlog)
    {
      socket->priv->listen_backlog = backlog;
      g_object_notify (G_OBJECT (socket), "listen-backlog");
    }
}

/**
 * g_socket_get_family:
 * @socket: a #GSocket.
 *
 * Gets the socket family of the socket.
 *
 * Returns: a #GSocketFamily
 *
 * Since: 2.22
 **/
GSocketFamily
g_socket_get_family (GSocket *socket)
{
  g_return_val_if_fail (G_IS_SOCKET (socket), G_SOCKET_FAMILY_INVALID);

  return socket->priv->family;
}

/**
 * g_socket_get_socket_type:
 * @socket: a #GSocket.
 *
 * Gets the socket type of the socket.
 *
 * Returns: a #GSocketType
 *
 * Since: 2.22
 **/
GSocketType
g_socket_get_socket_type (GSocket *socket)
{
  g_return_val_if_fail (G_IS_SOCKET (socket), G_SOCKET_TYPE_INVALID);

  return socket->priv->type;
}

/**
 * g_socket_get_protocol_id:
 * @socket: a #GSocket.
 *
 * Gets the socket protocol id the socket was created with.
 * In case the protocol is unknown, -1 is returned.
 *
 * Returns: a protocol id, or -1 if unknown
 *
 * Since: 2.22
 **/
gint
g_socket_get_protocol_id (GSocket *socket)
{
  g_return_val_if_fail (G_IS_SOCKET (socket), -1);

  return socket->priv->protocol;
}

/**
 * g_socket_get_protocol_name:
 * @socket: a #GSocket.
 *
 * Gets the socket protocol type name the socket was created with.
 * This can be %NULL if the socket was created with a NULL protocol.
 *
 * Returns: a string or %NULL, free with g_free
 *
 * Since: 2.22
 **/
char *
g_socket_get_protocol_name (GSocket *socket)
{
  g_return_val_if_fail (G_IS_SOCKET (socket), NULL);

  return get_protocol_name (socket->priv->protocol);
}

/**
 * g_socket_get_fd:
 * @socket: a #GSocket.
 *
 * Returns the underlying OS socket object. On unix this
 * is a socket file descriptor, and on windows this is
 * a Winsock2 SOCKET handle. This may be useful for
 * doing platform specific or otherwise unusual operations
 * on the socket.
 *
 * Returns: the file descriptor of the socket.
 *
 * Since: 2.22
 **/
int
g_socket_get_fd (GSocket *socket)
{
  g_return_val_if_fail (G_IS_SOCKET (socket), -1);

  return socket->priv->fd;
}

/**
 * g_socket_get_local_address:
 * @socket: a #GSocket.
 * @error: #GError for error reporting, or %NULL to ignore.
 *
 * Try to get the local address of a bound socket. This is only
 * useful if the socket has been bound to a local address.
 *
 * Returns: a #GSocketAddress or %NULL on error.
 *
 * Since: 2.22
 **/
GSocketAddress *
g_socket_get_local_address (GSocket  *socket,
                            GError  **error)
{
  gchar buffer[256];
  guint32 len = 256;

  g_return_val_if_fail (G_IS_SOCKET (socket), NULL);

  if (socket->priv->local_address)
    return socket->priv->local_address;

  if (getsockname (socket->priv->fd, (struct sockaddr *) buffer, &len) < 0)
    {
      int errsv = get_socket_errno ();
      g_set_error (error, G_IO_ERROR, socket_io_error_from_errno (errsv),
                   _("could not get local address: %s"), socket_strerror (errsv));
      return NULL;
    }

  socket->priv->local_address = g_socket_address_new_from_native (buffer, len);
  return socket->priv->local_address;
}

/**
 * g_socket_get_remote_address:
 * @socket: a #GSocket.
 * @error: #GError for error reporting, or %NULL to ignore.
 *
 * Try to get the remove address of a connected socket. This is only
 * useful for connection oriented sockets that have been connected.
 *
 * Returns: a #GSocketAddress or %NULL on error.
 *
 * Since: 2.22
 **/
GSocketAddress *
g_socket_get_remote_address (GSocket  *socket,
                             GError  **error)
{
  gchar buffer[256];
  guint32 len = 256;

  g_return_val_if_fail (G_IS_SOCKET (socket), NULL);

  if (socket->priv->remote_address)
    return socket->priv->remote_address;

  if (getpeername (socket->priv->fd, (struct sockaddr *) buffer, &len) < 0)
    {
      int errsv = get_socket_errno ();
      g_set_error (error, G_IO_ERROR, socket_io_error_from_errno (errsv),
                   _("could not get remote address: %s"), socket_strerror (errsv));
      return NULL;
    }

  socket->priv->remote_address = g_socket_address_new_from_native (buffer, len);
  return socket->priv->remote_address;
}

/**
 * g_socket_is_connected:
 * @socket: a #GSocket.
 *
 * Check whether the socket is connected. This is only useful for
 * connection-oriented sockets.
 *
 * Returns: %TRUE if socket is connected, %FALSE otherwise.
 *
 * Since: 2.22
 **/
gboolean
g_socket_is_connected (GSocket *socket)
{
  g_return_val_if_fail (G_IS_SOCKET (socket), FALSE);

  return socket->priv->remote_address != NULL;
}

/**
 * g_socket_listen:
 * @socket: a #GSocket.
 * @error: #GError for error reporting, or %NULL to ignore.
 *
 * Marks the socket as a server socket, i.e. a socket that is used
 * to accept incoming requests using g_socket_accept().
 *
 * Before calling this the socket must be bound to a local address using
 * g_socket_bind().
 *
 * Returns: %TRUE on success, %FALSE on error.
 *
 * Since: 2.22
 **/
gboolean
g_socket_listen (GSocket  *socket,
                 GError  **error)
{
  g_return_val_if_fail (G_IS_SOCKET (socket), FALSE);

  if (!check_socket (socket, error))
    return FALSE;

  if (listen (socket->priv->fd, socket->priv->listen_backlog) < 0)
    {
      int errsv = get_socket_errno ();

      g_set_error (error, G_IO_ERROR, socket_io_error_from_errno (errsv),
                   _("could not listen: %s"), socket_strerror (errsv));
      return FALSE;
    }

  return TRUE;
}

/**
 * g_socket_bind:
 * @socket: a #GSocket.
 * @address: a #GSocketAddress specifying the local address.
 * @allow_reuse: whether to allow reusing this address
 * @error: #GError for error reporting, or %NULL to ignore.
 *
 * When a socket is created it is attached to an address family, but it
 * doesn't have an address in this family. g_socket_bind() assigns the
 * address (sometimes called name) of the socket.
 *
 * It is generally required to bind to a local address before you can
 * receive connections. (See g_socket_listen() and g_socket_accept() ).
 *
 * If @allow_reuse is %TRUE this allows the bind call to succeed in some
 * situation where it would otherwise return a %G_IO_ERROR_ADDRESS_IN_USE
 * error. The main example is for a TCP server socket where there are
 * outstanding connections in the WAIT state, which are generally safe
 * to ignore. However, setting it to %TRUE doesn't mean the call will
 * succeed if there is a socket actively bound to the address.
 *
 * In general, pass %TRUE if the socket will be used to accept connections,
 * otherwise pass %FALSE.
 *
 * Returns: %TRUE on success, %FALSE on error.
 *
 * Since: 2.22
 **/
gboolean
g_socket_bind (GSocket         *socket,
               GSocketAddress  *address,
               gboolean         reuse_address,
               GError         **error)
{
  gchar addr[256];
  int value;

  g_return_val_if_fail (G_IS_SOCKET (socket) && G_IS_SOCKET_ADDRESS (address), FALSE);

  if (!check_socket (socket, error))
    return FALSE;

  /* SO_REUSEADDR on windows means something else and is not what we want.
     It always allows the unix variant of SO_REUSEADDR anyway */
#ifndef G_OS_WIN32
  value = (int) !!reuse_address;
  if (setsockopt (socket->priv->fd, SOL_SOCKET, SO_REUSEADDR,
                  (gpointer) &value, sizeof (value)) < 0)
    {
      int errsv = get_socket_errno ();
      g_set_error (error,
                   G_IO_ERROR, socket_io_error_from_errno (errsv),
                   _("Error setting reuse_address: %s"), socket_strerror (errsv));
      return FALSE;
    }
#endif

  if (!g_socket_address_to_native (address, addr, sizeof addr))
    return FALSE;

  if (bind (socket->priv->fd, (struct sockaddr *) addr,
            g_socket_address_get_native_size (address)) < 0)
    {
      int errsv = get_socket_errno ();
      g_set_error (error,
                   G_IO_ERROR, socket_io_error_from_errno (errsv),
                   _("Error binding to address: %s"), socket_strerror (errsv));
      return FALSE;
    }

  socket->priv->local_address = g_object_ref (address);

  return TRUE;
}

/**
 * g_socket_accept:
 * @socket: a #GSocket.
 * @error: #GError for error reporting, or %NULL to ignore.
 *
 * Accept incoming connections on a connection-based socket. This removes
 * the first outstanding connection request from the listening socket and
 * creates a #GSocket object for it.
 *
 * The @socket must be bound to a local address with g_socket_bind() and
 * must be listening for incoming connections (g_socket_listen()).
 *
 * If there are no outstanding connections then the operation will block
 * or return %G_IO_ERROR_WOULD_BLOCK if non-blocking I/O is enabled.
 * To be notified of an incoming connection, wait for the %G_IO_IN condition.
 *
 * Returns: a new #GSocket, or %NULL on error.
 *     Free the returned object with g_object_unref().
 *
 * Since: 2.22
 **/
GSocket *
g_socket_accept (GSocket       *socket,
                 GError       **error)
{
  GSocket *new_socket;
  gint ret;

  g_return_val_if_fail (G_IS_SOCKET (socket), NULL);

  if (!check_socket (socket, error))
    return NULL;

  while (1)
    {
      if (socket->priv->blocking &&
          !g_socket_condition_wait (socket,
                                    G_IO_IN, NULL, error))
        return NULL;

      if ((ret = accept (socket->priv->fd, NULL, 0)) < 0)
        {
          int errsv = get_socket_errno ();

          win32_unset_event_mask (socket, FD_ACCEPT);

          if (errsv == EINTR)
            continue;

          if (socket->priv->blocking)
            {
#ifdef WSAEWOULDBLOCK
              if (errsv == WSAEWOULDBLOCK)
                continue;
#else
              if (errsv == EWOULDBLOCK ||
                  errsv == EAGAIN)
                continue;
#endif
            }

          g_set_error (error, G_IO_ERROR,
                       socket_io_error_from_errno (errsv),
                       _("Error accepting connection: %s"), socket_strerror (errsv));
          return NULL;
        }
      break;
    }

  win32_unset_event_mask (socket, FD_ACCEPT);

#ifdef G_OS_WIN32
  {
    /* The socket inherits the accepting sockets event mask and even object,
       we need to remove that */
    WSAEventSelect (ret, NULL, 0);
  }
#else
  {
    int flags;

    /* We always want to set close-on-exec to protect users. If you
       need to so some weird inheritance to exec you can re-enable this
       using lower level hacks with g_socket_get_fd(). */
    flags = fcntl (ret, F_GETFD, 0);
    if (flags != -1 &&
        (flags & FD_CLOEXEC) == 0)
      {
        flags |= FD_CLOEXEC;
        fcntl (ret, F_SETFD, flags);
      }
  }
#endif

  new_socket = g_socket_new_from_fd (ret, error);
  if (new_socket == NULL)
    {
#ifdef G_OS_WIN32
      closesocket (ret);
#else
      close (ret);
#endif
    }
  else
    new_socket->priv->protocol = socket->priv->protocol;

  return new_socket;
}

/**
 * g_socket_connect:
 * @socket: a #GSocket.
 * @address: a #GSocketAddress specifying the remote address.
 * @error: #GError for error reporting, or %NULL to ignore.
 *
 * Connect the socket to the specified remote address.
 *
 * For connection oriented socket this generally means we attempt to make
 * a connection to the @address. For a connection-less socket it sets
 * the default address for g_socket_send() and discards all incoming datagrams
 * from other sources.
 *
 * Generally connection oriented sockets can only connect once, but connection-less
 * sockets can connect multiple times to change the default address.
 *
 * If the connect call needs to do network I/O it will block, unless
 * non-blocking I/O is enabled. Then %G_IO_ERROR_PENDING is returned
 * and the user can be notified of the connection finishing by waiting
 * for the G_IO_OUT condition. The result of the connection can then be
 * checked with g_socket_check_pending_error().
 *
 * Returns: %TRUE if connected, %FALSE on error.
 *
 * Since: 2.22
 **/
gboolean
g_socket_connect (GSocket         *socket,
                  GSocketAddress  *address,
                  GError         **error)
{
  gchar buffer[256];

  g_return_val_if_fail (G_IS_SOCKET (socket) && G_IS_SOCKET_ADDRESS (address), FALSE);

  if (!check_socket (socket, error))
    return FALSE;

  g_socket_address_to_native (address, buffer, sizeof buffer);

  while (1)
    {
      if (socket->priv->blocking &&
          !g_socket_condition_wait (socket,
                                    G_IO_IN, NULL, error))
        return FALSE;

      if (connect (socket->priv->fd, (struct sockaddr *) buffer,
                   g_socket_address_get_native_size (address)) < 0)
        {
          int errsv = get_socket_errno ();

          if (errsv == EINTR)
            continue;

#ifndef G_OS_WIN32
          if (errsv == EINPROGRESS)
#else
          if (errsv == WSAEINPROGRESS)
#endif
            {
              if (socket->priv->blocking)
                {
                  g_socket_condition_wait (socket, G_IO_OUT, NULL, NULL);
                  if (g_socket_check_pending_error (socket, error))
                    break;
                  else
                    g_prefix_error (error, _("Error connecting: "));
                }
              else
                g_set_error (error, G_IO_ERROR, G_IO_ERROR_PENDING,
                             _("Connection in progress"));
            }
          else
            g_set_error (error, G_IO_ERROR,
                         socket_io_error_from_errno (errsv),
                         _("Error connecting: %s"), socket_strerror (errsv));

          return FALSE;
        }
      break;
    }

  win32_unset_event_mask (socket, FD_CONNECT);

  socket->priv->remote_address = g_object_ref (address);

  return TRUE;
}

/**
 * g_socket_check_pending_error:
 * @socket: a #GSocket
 * @error: #GError for error reporting, or %NULL to ignore.
 *
 * Checks and resets the pending error for the socket. This is typically
 * used to check for errors when g_socket_connect() is used in non-blocking mode.
 *
 * Returns: %TRUE if no error, %FALSE otherwise, setting @error to the error
 *
 * Since: 2.22
 **/
gboolean
g_socket_check_pending_error (GSocket  *socket,
                              GError  **error)
{
  guint optlen;
  int value;

  optlen = sizeof (value);
  if (getsockopt (socket->priv->fd, SOL_SOCKET, SO_ERROR, (void *)&value, &optlen) != 0)
    {
      int errsv = get_socket_errno ();

      g_set_error (error, G_IO_ERROR, socket_io_error_from_errno (errsv),
                   _("Unable to get pending error: %s"), socket_strerror (errsv));
      return FALSE;
    }

  if (value != 0)
    {
      g_set_error (error, G_IO_ERROR, socket_io_error_from_errno (value),
                   "%s", socket_strerror (value));
      return FALSE;
    }
  return TRUE;
}

/**
 * g_socket_receive:
 * @socket: a #GSocket
 * @buffer: a buffer to read data into (which should be at least count bytes long).
 * @size: the number of bytes that will be read from the stream
 * @error: #GError for error reporting, or %NULL to ignore.
 *
 * Receive data (up to @size bytes) from a socket. This is mainly used by
 * connection oriented sockets, it is identical to g_socket_receive_from()
 * with @address set to %NULL.
 *
 * If a message is too long to fit in @buffer, excess bytes may be discarded
 * depending on the type of socket the message is received from.
 *
 * If the socket is in blocking mode the call will block until there is
 * some data to receive or there is an error. If there is no data available
 * and the socket is in non-blocking mode a %G_IO_ERROR_WOULD_BLOCK error
 * will be returned. To be notified of available data, wait for the %G_IO_IN
 * condition.
 *
 * On error -1 is returned and @error is set accordingly.
 *
 * Returns: Number of bytes read, or -1 on error
 *
 * Since: 2.22
 **/
gssize
g_socket_receive (GSocket       *socket,
                  gchar         *buffer,
                  gsize          size,
                  GError       **error)
{
  gssize ret;

  g_return_val_if_fail (G_IS_SOCKET (socket) && buffer != NULL, FALSE);

  if (!check_socket (socket, error))
    return -1;

  while (1)
    {
      if (socket->priv->blocking &&
          !g_socket_condition_wait (socket,
                                    G_IO_IN, NULL, error))
        return -1;

      if ((ret = recv (socket->priv->fd, buffer, size, 0)) < 0)
        {
          int errsv = get_socket_errno ();

          if (errsv == EINTR)
            continue;

          if (socket->priv->blocking)
            {
#ifdef WSAEWOULDBLOCK
              if (errsv == WSAEWOULDBLOCK)
                continue;
#else
              if (errsv == EWOULDBLOCK ||
                  errsv == EAGAIN)
                continue;
#endif
            }

          win32_unset_event_mask (socket, FD_READ);

          g_set_error (error, G_IO_ERROR,
                       socket_io_error_from_errno (errsv),
                       _("Error receiving data: %s"), socket_strerror (errsv));
          return -1;
        }

      win32_unset_event_mask (socket, FD_READ);

      break;
    }

  return ret;
}

/**
 * g_socket_receive_from:
 * @socket: a #GSocket
 * @address: a pointer to a #GSocketAddress pointer, or %NULL
 * @buffer: a buffer to read data into (which should be at least count bytes long).
 * @size: the number of bytes that will be read from the stream
 * @error: #GError for error reporting, or %NULL to ignore.
 *
 * Receive data (up to @size bytes) from a socket.
 *
 * If @address is non-%NULL then @address will be set equal to the
 * source address of the received packet.
 * @address is owned by the caller.
 *
 * If the socket is in blocking mode the call will block until there is
 * some data to receive or there is an error. If there is no data available
 * and the socket is in non-blocking mode a %G_IO_ERROR_WOULD_BLOCK error
 * will be returned. To be notified of available data, wait for the %G_IO_IN
 * condition.
 *
 * On error -1 is returned and @error is set accordingly.
 *
 * Returns: Number of bytes read, or -1 on error
 *
 * Since: 2.22
 **/
gssize
g_socket_receive_from (GSocket       *socket,
                       GSocketAddress  **address,
                       gchar         *buffer,
                       gsize          size,
                       GError       **error)
{
  GInputVector v;

  v.buffer = buffer;
  v.size = size;

  return g_socket_receive_message (socket,
                                   address,
                                   &v, 1,
                                   NULL, 0, NULL,
                                   error);
}

/**
 * g_socket_send:
 * @socket: a #GSocket
 * @buffer: the buffer containing the data to send.
 * @size: the number of bytes to send
 * @error: #GError for error reporting, or %NULL to ignore.
 *
 * Tries to send @size bytes from @buffer on the socket. This is mainly used by
 * connection oriented sockets, it is identical to g_socket_send_to()
 * with @address set to %NULL.
 *
 * If the socket is in blocking mode the call will block until there is
 * space for the data in the socket queue. If there is no space available
 * and the socket is in non-blocking mode a %G_IO_ERROR_WOULD_BLOCK error
 * will be returned. To be notified of available space, wait for the %G_IO_OUT
 * condition.
 *
 * Note that on Windows you can't rely on a %G_IO_OUT condition
 * not producing a %G_IO_ERROR_WOULD_BLOCK error, as this is how Winsock
 * write notification works. However, robust apps should always be able to
 * handle this since it can easily appear in other cases too.
 *
 * On error -1 is returned and @error is set accordingly.
 *
 * Returns: Number of bytes read, or -1 on error
 *
 * Since: 2.22
 **/
gssize
g_socket_send (GSocket      *socket,
               const gchar  *buffer,
               gsize         size,
               GError      **error)
{
  gssize ret;

  g_return_val_if_fail (G_IS_SOCKET (socket) && buffer != NULL, FALSE);

  if (!check_socket (socket, error))
    return -1;

  while (1)
    {
      if (socket->priv->blocking &&
          !g_socket_condition_wait (socket,
                                    G_IO_OUT, NULL, error))
        return -1;

      if ((ret = send (socket->priv->fd, buffer, size, 0)) < 0)
        {
          int errsv = get_socket_errno ();

          if (errsv == EINTR)
            continue;

#ifdef WSAEWOULDBLOCK
          if (errsv == WSAEWOULDBLOCK)
            win32_unset_event_mask (socket, FD_WRITE);
#endif

          if (socket->priv->blocking)
            {
#ifdef WSAEWOULDBLOCK
              if (errsv == WSAEWOULDBLOCK)
                continue;
#else
              if (errsv == EWOULDBLOCK ||
                  errsv == EAGAIN)
                continue;
#endif
            }

          g_set_error (error, G_IO_ERROR,
                       socket_io_error_from_errno (errsv),
                       _("Error sending data: %s"), socket_strerror (errsv));
          return -1;
        }
      break;
    }

  return ret;
}

/**
 * g_socket_send_to:
 * @socket: a #GSocket
 * @address: a #GSocketAddress, or %NULL
 * @buffer: the buffer containing the data to send.
 * @size: the number of bytes to send
 * @error: #GError for error reporting, or %NULL to ignore.
 *
 * Tries to send @size bytes from @buffer to @address. If @address is
 * %NULL then the message is sent to the default receiver (set by
 * g_socket_connect()).
 *
 * If the socket is in blocking mode the call will block until there is
 * space for the data in the socket queue. If there is no space available
 * and the socket is in non-blocking mode a %G_IO_ERROR_WOULD_BLOCK error
 * will be returned. To be notified of available space, wait for the %G_IO_OUT
 * condition.
 *
 * Note that on Windows you can't rely on a %G_IO_OUT condition
 * not producing a %G_IO_ERROR_WOULD_BLOCK error, as this is how Winsock
 * write notification works. However, robust apps should always be able to
 * handle this since it can easily appear in other cases too.
 *
 * On error -1 is returned and @error is set accordingly.
 *
 * Returns: Number of bytes read, or -1 on error
 *
 * Since: 2.22
 **/
gssize
g_socket_send_to (GSocket      *socket,
                  GSocketAddress *address,
                  const gchar  *buffer,
                  gsize         size,
                  GError      **error)
{
  GOutputVector v;

  v.buffer = buffer;
  v.size = size;

  return g_socket_send_message (socket,
                                address,
                                &v, 1,
                                NULL, 0,
                                0, error);
}

/**
 * g_socket_close:
 * @socket: a #GSocket
 * @error: #GError for error reporting, or %NULL to ignore.
 *
 * Closes the socket, shutting down any active connection.
 *
 * Closing a socket does not wait for all outstanding I/O operations to finish,
 * so the caller should not rely on them to be guaranteed to complete even
 * if the close returns with no error.
 *
 * Once the socket is closed, all other operations will return %G_IO_ERROR_CLOSED.
 * Closing a stream multiple times will not return an error.
 *
 * Sockets will be automatically closed when the last reference
 * is dropped, but you might want to call this function to make sure
 * resources are released as early as possible.
 *
 * Returns: %TRUE on success, %FALSE on error
 *
 * Since: 2.22
 **/
gboolean
g_socket_close (GSocket *socket,
                GError **error)
{
  int res;

  g_return_val_if_fail (G_IS_SOCKET (socket), TRUE);

  if (socket->priv->closed)
    return TRUE; /* Multiple close not an error */

  if (!check_socket (socket, NULL))
    return FALSE;

  while (1)
    {
#ifdef G_OS_WIN32
      res = closesocket (socket->priv->fd);
#else
      res = close (socket->priv->fd);
#endif
      if (res == -1)
        {
          int errsv = get_socket_errno ();

          if (errsv == EINTR)
            continue;

          g_set_error (error, G_IO_ERROR,
                       socket_io_error_from_errno (errsv),
                       _("Error closing socket: %s"),
                       socket_strerror (errsv));
          return FALSE;
        }
      break;
    }

#ifdef G_OS_WIN32
  if (socket->priv->event != WSA_INVALID_EVENT)
    {
      WSACloseEvent (socket->priv->event);
      socket->priv->event = WSA_INVALID_EVENT;
    }
#endif

  socket->priv->closed = TRUE;

  return TRUE;
}

/**
 * g_socket_is_closed:
 * @socket: a #GSocket
 *
 * Checks whether a socket is closed.
 *
 * Returns: %TRUE if socket is closed, %FALSE otherwise
 *
 * Since: 2.22
 **/
gboolean
g_socket_is_closed (GSocket *socket)
{
  return socket->priv->closed;
}

#ifdef G_OS_WIN32
/* Broken source, used on errors */
static gboolean
broken_prepare  (GSource  *source,
                 gint     *timeout)
{
  return FALSE;
}

static gboolean
broken_check    (GSource  *source)
{
  return FALSE;
}

static gboolean
broken_dispatch (GSource    *source,
                 GSourceFunc callback,
                 gpointer    user_data)
{
  return TRUE;
}

static GSourceFuncs broken_funcs =
{
  broken_prepare,
  broken_check,
  broken_dispatch,
  NULL
};

static gint
network_events_for_condition (GIOCondition condition)
{
  int event_mask = 0;

  if (condition & G_IO_IN)
    event_mask |= (FD_READ | FD_ACCEPT);
  if (condition & G_IO_OUT)
    event_mask |= (FD_WRITE | FD_CONNECT);
  event_mask |= FD_CLOSE;

  return event_mask;
}

static void
ensure_event (GSocket *socket)
{
  if (socket->priv->event == WSA_INVALID_EVENT)
    socket->priv->event = WSACreateEvent();
}

static void
update_select_events (GSocket *socket)
{
  int event_mask;
  GIOCondition *ptr;
  GList *l;
  WSAEVENT event;

  ensure_event (socket);

  event_mask = 0;
  for (l = socket->priv->requested_conditions; l != NULL; l = l->next)
    {
      ptr = l->data;
      event_mask |= network_events_for_condition (*ptr);
    }

  if (event_mask != socket->priv->selected_events)
    {
      /* If no events selected, disable event so we can unset
         nonblocking mode */

      if (event_mask == 0)
        event = NULL;
      else
        event = socket->priv->event;

      if (WSAEventSelect (socket->priv->fd, event, event_mask) == 0)
        socket->priv->selected_events = event_mask;
    }
}

static void
add_condition_watch (GSocket *socket,
                     GIOCondition *condition)
{
  g_assert (g_list_find (socket->priv->requested_conditions, condition) == NULL);

  socket->priv->requested_conditions =
    g_list_prepend (socket->priv->requested_conditions, condition);

  update_select_events (socket);
}

static void
remove_condition_watch (GSocket *socket,
                        GIOCondition *condition)
{
  g_assert (g_list_find (socket->priv->requested_conditions, condition) != NULL);

  socket->priv->requested_conditions =
    g_list_remove (socket->priv->requested_conditions, condition);

  update_select_events (socket);
}

static GIOCondition
update_condition (GSocket *socket)
{
  WSANETWORKEVENTS events;
  GIOCondition condition;

  if (WSAEnumNetworkEvents (socket->priv->fd,
                            socket->priv->event,
                            &events) == 0)
    {
      socket->priv->current_events |= events.lNetworkEvents;
      if (events.lNetworkEvents & FD_WRITE &&
          events.iErrorCode[FD_WRITE_BIT] != 0)
        socket->priv->current_errors |= FD_WRITE;
      if (events.lNetworkEvents & FD_CONNECT &&
          events.iErrorCode[FD_CONNECT_BIT] != 0)
        socket->priv->current_errors |= FD_CONNECT;
    }

  condition = 0;
  if (socket->priv->current_events & (FD_READ | FD_ACCEPT))
    condition |= G_IO_IN;

  if (socket->priv->current_events & FD_CLOSE ||
      socket->priv->closed)
    condition |= G_IO_HUP;

  /* Never report both G_IO_OUT and HUP, these are
     mutually exclusive (can't write to a closed socket) */
  if ((condition & G_IO_HUP) == 0 &&
      socket->priv->current_events & FD_WRITE)
    {
      if (socket->priv->current_errors & FD_WRITE)
        condition |= G_IO_ERR;
      else
        condition |= G_IO_OUT;
    }
  else
    {
      if (socket->priv->current_events & FD_CONNECT)
        {
          if (socket->priv->current_errors & FD_CONNECT)
            condition |= (G_IO_HUP | G_IO_ERR);
          else
            condition |= G_IO_OUT;
        }
    }

  return condition;
}

typedef struct {
  GSource       source;
  GPollFD       pollfd;
  GSocket      *socket;
  GIOCondition  condition;
  GCancellable *cancellable;
  GPollFD       cancel_pollfd;
  GIOCondition  result_condition;
} GWinsockSource;

static gboolean
winsock_prepare (GSource  *source,
                 gint     *timeout)
{
  GWinsockSource *winsock_source = (GWinsockSource *)source;
  GIOCondition current_condition;

  current_condition = update_condition (winsock_source->socket);

  if (g_cancellable_is_cancelled (winsock_source->cancellable))
    {
      winsock_source->result_condition = current_condition;
      return TRUE;
    }

  if ((winsock_source->condition & current_condition) != 0)
    {
      winsock_source->result_condition = current_condition;
      return TRUE;
    }

  return FALSE;
}

static gboolean
winsock_check (GSource  *source)
{
  GWinsockSource *winsock_source = (GWinsockSource *)source;
  GIOCondition current_condition;

  current_condition = update_condition (winsock_source->socket);

  if (g_cancellable_is_cancelled (winsock_source->cancellable))
    {
      winsock_source->result_condition = current_condition;
      return TRUE;
    }

  if ((winsock_source->condition & current_condition) != 0)
    {
      winsock_source->result_condition = current_condition;
      return TRUE;
    }

  return FALSE;
}

static gboolean
winsock_dispatch (GSource    *source,
                  GSourceFunc callback,
                  gpointer    user_data)
{
  GSocketSourceFunc func = (GSocketSourceFunc)callback;
  GWinsockSource *winsock_source = (GWinsockSource *)source;

  return (*func) (winsock_source->socket,
                  winsock_source->result_condition & winsock_source->condition,
                  user_data);
}

static void
winsock_finalize (GSource *source)
{
  GWinsockSource *winsock_source = (GWinsockSource *)source;
  GSocket *socket;

  socket = winsock_source->socket;

  remove_condition_watch (socket, &winsock_source->condition);
  g_object_unref (socket);

  if (winsock_source->cancellable)
    g_object_unref (winsock_source->cancellable);
}

static GSourceFuncs winsock_funcs =
{
  winsock_prepare,
  winsock_check,
  winsock_dispatch,
  winsock_finalize
};

static GSource *
winsock_source_new (GSocket      *socket,
                    GIOCondition  condition,
                    GCancellable *cancellable)
{
  GSource *source;
  GWinsockSource *winsock_source;

  ensure_event (socket);

  if (socket->priv->event == WSA_INVALID_EVENT)
    {
      g_warning ("Failed to create WSAEvent");
      return g_source_new (&broken_funcs, sizeof (GSource));
    }

  condition |= G_IO_HUP | G_IO_ERR;

  source = g_source_new (&winsock_funcs, sizeof (GWinsockSource));
  winsock_source = (GWinsockSource *)source;

  winsock_source->socket = g_object_ref (socket);
  winsock_source->condition = condition;
  add_condition_watch (socket, &winsock_source->condition);

  if (cancellable)
    {
      winsock_source->cancellable = g_object_ref (cancellable);
      g_cancellable_make_pollfd (cancellable,
                                 &winsock_source->cancel_pollfd);
      g_source_add_poll (source, &winsock_source->cancel_pollfd);
    }

  winsock_source->pollfd.fd = (gintptr) socket->priv->event;
  winsock_source->pollfd.events = condition;
  g_source_add_poll (source, &winsock_source->pollfd);

  return source;
}
#endif

/**
 * g_socket_create_source:
 * @socket: a #GSocket
 * @condition: a #GIOCondition mask to monitor
 * @cancellable: a %GCancellable or %NULL
 *
 * Creates a %GSource that can be attached to a %GMainContext to monitor
 * for the availibility of the specified @condition on the socket.
 *
 * The callback on the source is of the #GSocketSourceFunc type.
 *
 * It is meaningless to specify %G_IO_ERR or %G_IO_HUP in condition;
 * these conditions will always be reported output if they are true.
 *
 * @cancellable if not %NULL can be used to cancel the source, which will
 * cause the source to trigger, reporting the current condition. You can
 * check for this in the callback using g_cancellable_is_cancelled().
 *
 * Returns: a newly allocated %GSource, free with g_source_unref().
 *
 * Since: 2.22
 **/
GSource *
g_socket_create_source (GSocket      *socket,
                        GIOCondition  condition,
                        GCancellable *cancellable)
{
  GSource *source;
  g_return_val_if_fail (G_IS_SOCKET (socket) && (cancellable == NULL || G_IS_CANCELLABLE (cancellable)), NULL);

#ifdef G_OS_WIN32
  source = winsock_source_new (socket, condition, cancellable);
#else
  source =_g_fd_source_new_with_object (G_OBJECT (socket), socket->priv->fd,
                                        condition, cancellable);
#endif
  return source;
}

/**
 * g_socket_condition_check:
 * @socket: a #GSocket
 * @condition: a #GIOCondition mask to check
 *
 * Checks on the readiness of @socket to perform operations.  The
 * operations specified in @condition are checked for and masked
 * against the currently-satisfied conditions on @socket.  The result
 * is returned.
 *
 * It is meaningless to specify %G_IO_ERR or %G_IO_HUP in condition;
 * these conditions will always be set in the output if they are true.
 *
 * This call never blocks.
 *
 * Returns: the @GIOCondition mask of the current state
 *
 * Since: 2.22
 **/
GIOCondition
g_socket_condition_check (GSocket       *socket,
                          GIOCondition   condition)
{
  if (!check_socket (socket, NULL))
    return 0;

#ifdef G_OS_WIN32
  {
    GIOCondition current_condition;

    condition |= G_IO_ERR | G_IO_HUP;

    add_condition_watch (socket, &condition);
    current_condition = update_condition (socket);
    remove_condition_watch (socket, &condition);
    return condition & current_condition;
  }
#else
  {
    GPollFD poll_fd;
    gint result;
    poll_fd.fd = socket->priv->fd;
    poll_fd.events = condition;

    do
      result = g_poll (&poll_fd, 1, 0);
    while (result == -1 && get_socket_errno () == EINTR);

    return poll_fd.revents;
  }
#endif
}

/**
 * g_socket_condition_wait:
 * @socket: a #GSocket
 * @condition: a #GIOCondition mask to wait for
 * @cancellable: a #GCancellable, or %NULL
 * @error: a #GError pointer, or %NULL
 *
 * Waits for @condition to become true on @socket.  When the condition
 * becomes true, %TRUE is returned.
 *
 * If @cancellable is cancelled before the condition becomes true then
 * %FALSE is returned and @error, if non-%NULL, is set to %G_IO_ERROR_CANCELLED.
 *
 * Returns: %TRUE if the condition was met, %FALSE otherwise
 *
 * Since: 2.22
 **/
gboolean
g_socket_condition_wait (GSocket       *socket,
                         GIOCondition   condition,
                         GCancellable  *cancellable,
                         GError       **error)
{
  if (!check_socket (socket, error))
    return FALSE;

  if (g_cancellable_set_error_if_cancelled (cancellable, error))
    return FALSE;

#ifdef G_OS_WIN32
  {
    GIOCondition current_condition;
    WSAEVENT events[2];
    DWORD res;
    GPollFD cancel_fd;
    int num_events;

    /* Always check these */
    condition |=  G_IO_ERR | G_IO_HUP;

    add_condition_watch (socket, &condition);

    num_events = 0;
    events[num_events++] = socket->priv->event;

    if (cancellable)
      {
        g_cancellable_make_pollfd (cancellable, &cancel_fd);
        events[num_events++] = (WSAEVENT)cancel_fd.fd;
      }

    current_condition = update_condition (socket);
    while ((condition & current_condition) == 0)
      {
        res = WSAWaitForMultipleEvents(num_events, events,
                                       FALSE, WSA_INFINITE, FALSE);
        if (res == WSA_WAIT_FAILED)
          {
            int errsv = get_socket_errno ();

            g_set_error (error, G_IO_ERROR,
                         socket_io_error_from_errno (errsv),
                         _("Waiting for socket condition: %s"),
                         socket_strerror (errsv));
            break;
          }

        if (g_cancellable_set_error_if_cancelled (cancellable, error))
          break;

        current_condition = update_condition (socket);
      }
    remove_condition_watch (socket, &condition);

    return (condition & current_condition) != 0;
  }
#else
  {
    GPollFD poll_fd[2];
    gint result;
    gint num;

    poll_fd[0].fd = socket->priv->fd;
    poll_fd[0].events = condition;
    num = 1;

    if (cancellable)
      {
        g_cancellable_make_pollfd (cancellable, &poll_fd[1]);
        num++;
      }

    do
      result = g_poll (poll_fd, num, -1);
    while (result == -1 && get_socket_errno () == EINTR);

    return cancellable == NULL ||
      !g_cancellable_set_error_if_cancelled (cancellable, error);
  }
  #endif
}

/**
 * g_socket_send_message:
 * @socket: a #GSocket
 * @address: a #GSocketAddress, or %NULL
 * @vectors: an array of #GOutputVector structs
 * @num_vectors: the number of elements in @vectors, or -1
 * @messages: a pointer to an array of #GSocketControlMessages, or
 *   %NULL.
 * @num_messages: number of elements in @messages, or -1.
 * @flags: an int containing #GSocketMsgFlags flags
 * @error: #GError for error reporting, or %NULL to ignore.
 *
 * Send data to @address on @socket.  This is the most complicated and
 * fully-featured version of this call. For easier use, see
 * g_socket_send() and g_socket_send_to().
 *
 * If @address is %NULL then the message is sent to the default receiver
 * (set by g_socket_connect()).
 *
 * @vector must point to an array of #GOutputVector structs and
 * @num_vectors must be the length of this array.  These structs
 * describe the buffers that the sent data will be gathered from.
 * If @num_vector is -1, then @vector is assumed to be terminated
 * by a #GOutputVector with a %NULL buffer pointer.
 *
 *
 * @messages, if non-%NULL, is taken to point to an array of @num_messages
 * #GSocketControlMessage instances. These correspond to the control
 * messages to be sent on the socket.
 * If @num_messages is -1 then @messages is treated as a %NULL-terminated
 * array.
 *
 * @flags modify how the message sent. The commonly available arguments
 * for this is available in the #GSocketMsgFlags enum, but the
 * values there are the same as the system values, and the flags
 * are passed in as-is, so you can pass in system specific flags too.
 *
 * If the socket is in blocking mode the call will block until there is
 * space for the data in the socket queue. If there is no space available
 * and the socket is in non-blocking mode a %G_IO_ERROR_WOULD_BLOCK error
 * will be returned. To be notified of available space, wait for the %G_IO_OUT
 * condition.
 *
 * Note that on Windows you can't rely on a %G_IO_OUT condition
 * not producing a %G_IO_ERROR_WOULD_BLOCK error, as this is how Winsock
 * write notification works. However, robust apps should always be able to
 * handle this since it can easily appear in other cases too.
 *
 * On error -1 is returned and @error is set accordingly.
 *
 * Returns: Number of bytes read, or -1 on error
 *
 * Since: 2.22
 **/
gssize
g_socket_send_message (GSocket                *socket,
                       GSocketAddress         *address,
                       GOutputVector          *vectors,
                       gint                    num_vectors,
                       GSocketControlMessage **messages,
                       gint                    num_messages,
                       gint                    flags,
                       GError                **error)
{
  GOutputVector one_vector;
  char zero;

  if (!check_socket (socket, error))
    return -1;

  if (num_vectors == -1)
    {
      for (num_vectors = 0;
           vectors[num_vectors].buffer != NULL;
           num_vectors++)
        ;
    }

  if (num_messages == -1)
    {
      for (num_messages = 0;
           messages != NULL && messages[num_messages] != NULL;
           num_messages++)
        ;
    }

  if (num_vectors == 0)
    {
      zero = '\0';

      one_vector.buffer = &zero;
      one_vector.size = 1;
      num_vectors = 1;
      vectors = &one_vector;
    }

#ifndef G_OS_WIN32
  {
    struct msghdr msg;
    gssize result;

    /* name */
    if (address)
      {
        msg.msg_namelen = g_socket_address_get_native_size (address);
        msg.msg_name = g_alloca (msg.msg_namelen);
        g_socket_address_to_native (address, msg.msg_name, msg.msg_namelen);
      }

    /* iov */
    {
      /* this entire expression will be evaluated at compile time */
      if (sizeof *msg.msg_iov == sizeof *vectors &&
          sizeof msg.msg_iov->iov_base == sizeof vectors->buffer &&
          G_STRUCT_OFFSET (struct iovec, iov_base) ==
          G_STRUCT_OFFSET (GOutputVector, buffer) &&
          sizeof msg.msg_iov->iov_len == sizeof vectors->size &&
          G_STRUCT_OFFSET (struct iovec, iov_len) ==
          G_STRUCT_OFFSET (GOutputVector, size))
        /* ABI is compatible */
        {
          msg.msg_iov = (struct iovec *) vectors;
          msg.msg_iovlen = num_vectors;
        }
      else
        /* ABI is incompatible */
        {
          gint i;

          msg.msg_iov = g_newa (struct iovec, num_vectors);
          for (i = 0; i < num_vectors; i++)
            {
              msg.msg_iov[i].iov_base = (void *) vectors[i].buffer;
              msg.msg_iov[i].iov_len = vectors[i].size;
            }
          msg.msg_iovlen = num_vectors;
        }
    }

    /* control */
    {
      struct cmsghdr *cmsg;
      gint i;

      msg.msg_controllen = 0;
      for (i = 0; i < num_messages; i++)
        msg.msg_controllen += CMSG_SPACE (g_socket_control_message_get_size (messages[i]));

      msg.msg_control = g_alloca (msg.msg_controllen);

      cmsg = CMSG_FIRSTHDR (&msg);
      for (i = 0; i < num_messages; i++)
        {
          cmsg->cmsg_level = g_socket_control_message_get_level (messages[i]);
          cmsg->cmsg_type = g_socket_control_message_get_msg_type (messages[i]);
          cmsg->cmsg_len = CMSG_LEN (g_socket_control_message_get_size (messages[i]));
          g_socket_control_message_serialize (messages[i],
                                              CMSG_DATA (cmsg));
          cmsg = CMSG_NXTHDR (&msg, cmsg);
        }
      g_assert (cmsg == NULL);
    }

    while (1)
      {
        if (socket->priv->blocking &&
            !g_socket_condition_wait (socket,
                                      G_IO_OUT, NULL, error))
          return -1;

        result = sendmsg (socket->priv->fd, &msg, flags);
        if (result < 0)
          {
            int errsv = get_socket_errno ();

            if (errsv == EINTR)
              continue;

            if (socket->priv->blocking &&
                (errsv == EWOULDBLOCK ||
                 errsv == EAGAIN))
              continue;

            g_set_error (error, G_IO_ERROR,
                         socket_io_error_from_errno (errsv),
                         _("Error sending message: %s"), socket_strerror (errsv));

            return -1;
          }
        break;
      }

    return result;
  }
#else
  {
    struct sockaddr_storage addr;
    guint addrlen;
    DWORD bytes_sent;
    int result;
    WSABUF *bufs;
    gint i;

    /* Win32 doesn't support control messages.
       Actually this is possible for raw and datagram sockets
       via WSASendMessage on Vista or later, but that doesn't
       seem very useful */
    if (num_messages != 0)
      {
        g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
                     _("GSocketControlMessage not supported on windows"));
        return -1;
      }

    /* iov */
    bufs = g_newa (WSABUF, num_vectors);
    for (i = 0; i < num_vectors; i++)
      {
        bufs[i].buf = (char *)vectors[i].buffer;
        bufs[i].len = (gulong)vectors[i].size;
      }

    /* name */
    if (address)
      {
        addrlen = g_socket_address_get_native_size (address);
        g_socket_address_to_native (address, &addr, sizeof addr);
      }

    while (1)
      {
        if (socket->priv->blocking &&
            !g_socket_condition_wait (socket,
                                      G_IO_OUT, NULL, error))
          return -1;

        if (address)
          result = WSASendTo (socket->priv->fd,
                              bufs, num_vectors,
                              &bytes_sent, flags,
                              (const struct sockaddr *)&addr, addrlen,
                              NULL, NULL);
        else
          result = WSASend (socket->priv->fd,
                            bufs, num_vectors,
                            &bytes_sent, flags,
                            NULL, NULL);

        if (result != 0)
          {
            int errsv = get_socket_errno ();

            if (errsv == WSAEINTR)
              continue;

            if (errsv == WSAEWOULDBLOCK)
              win32_unset_event_mask (socket, FD_WRITE);

            if (socket->priv->blocking &&
                errsv == WSAEWOULDBLOCK)
              continue;

            g_set_error (error, G_IO_ERROR,
                         socket_io_error_from_errno (errsv),
                         _("Error sending message: %s"), socket_strerror (errsv));

            return -1;
          }
        break;
      }

    return bytes_sent;
  }
#endif
}

/**
 * g_socket_receive_message:
 * @socket: a #GSocket
 * @address: a pointer to a #GSocketAddress pointer, or %NULL
 * @vectors: an array of #GInputVector structs
 * @num_vectors: the number of elements in @vectors, or -1
 * @messages: a pointer which will be filled with an array of
 *     #GSocketControlMessages, or %NULL
 * @num_messages: a pointer which will be filled with the number of
 *    elements in @messages, or %NULL
 * @flags: a pointer to an int containing #GSocketMsgFlags flags
 * @error: a #GError pointer, or %NULL
 *
 * Receive data from a socket.  This is the most complicated and
 * fully-featured version of this call. For easier use, see
 * g_socket_receive() and g_socket_receive_from().
 *
 * If @address is non-%NULL then @address will be set equal to the
 * source address of the received packet.
 * @address is owned by the caller.
 *
 * @vector must point to an array of #GInputVector structs and
 * @num_vectors must be the length of this array.  These structs
 * describe the buffers that received data will be scattered into.
 * If @num_vector is -1, then @vector is assumed to be terminated
 * by a #GInputVector with a %NULL buffer pointer.
 *
 * As a special case, if the size of the array is zero (in which case,
 * @vectors may of course be %NULL), then a single byte is received
 * and discarded.  This is to facilitate the common practice of
 * sending a single '\0' byte for the purposes of transferring
 * ancillary data.
 *
 * @messages, if non-%NULL, is taken to point to a pointer that will
 * be set to point to a newly-allocated array of
 * #GSocketControlMessage instances.  These correspond to the control
 * messages received from the kernel, one #GSocketControlMessage per
 * message from the kernel.  This array is %NULL-terminated and must be
 * freed by the caller using g_free().
 *
 * @num_messages, if non-%NULL, will be set to the number of control
 * messages received.
 *
 * If both @messages and @num_messages are non-%NULL, then
 * @num_messages gives the number of #GSocketControlMessage instances
 * in @messages (ie: not including the %NULL terminator).
 *
 * @flags is an in/out parameter. The commonly available arguments
 * for this is available in the #GSocketMsgFlags enum, but the
 * values there are the same as the system values, and the flags
 * are passed in as-is, so you can pass in system specific flags too.
 *
 * If the socket is in blocking mode the call will block until there is
 * some data to receive or there is an error. If there is no data available
 * and the socket is in non-blocking mode a %G_IO_ERROR_WOULD_BLOCK error
 * will be returned. To be notified of available data, wait for the %G_IO_IN
 * condition.
 *
 * On error -1 is returned and @error is set accordingly.
 *
 * Returns: Number of bytes read, or -1 on error
 *
 * Since: 2.22
 **/
gssize
g_socket_receive_message (GSocket                 *socket,
                          GSocketAddress         **address,
                          GInputVector            *vectors,
                          gint                     num_vectors,
                          GSocketControlMessage ***messages,
                          gint                    *num_messages,
                          gint                    *flags,
                          GError                 **error)
{
  GInputVector one_vector;
  char one_byte;

  if (!check_socket (socket, error))
    return -1;

  if (num_vectors == -1)
    {
      for (num_vectors = 0;
           vectors[num_vectors].buffer != NULL;
           num_vectors++)
        ;
    }

  if (num_vectors == 0)
    {
      one_vector.buffer = &one_byte;
      one_vector.size = 1;
      num_vectors = 1;
      vectors = &one_vector;
    }

#ifndef G_OS_WIN32
  {
    struct msghdr msg;
    gssize result;
    struct sockaddr_storage one_sockaddr;

    /* name */
    if (address)
      {
        msg.msg_name = &one_sockaddr;
        msg.msg_namelen = sizeof (struct sockaddr_storage);
      }
    else
      {
        msg.msg_name = NULL;
        msg.msg_namelen = 0;
      }

    /* iov */
    /* this entire expression will be evaluated at compile time */
    if (sizeof *msg.msg_iov == sizeof *vectors &&
        sizeof msg.msg_iov->iov_base == sizeof vectors->buffer &&
        G_STRUCT_OFFSET (struct iovec, iov_base) ==
        G_STRUCT_OFFSET (GInputVector, buffer) &&
        sizeof msg.msg_iov->iov_len == sizeof vectors->size &&
        G_STRUCT_OFFSET (struct iovec, iov_len) ==
        G_STRUCT_OFFSET (GInputVector, size))
      /* ABI is compatible */
      {
        msg.msg_iov = (struct iovec *) vectors;
        msg.msg_iovlen = num_vectors;
      }
    else
      /* ABI is incompatible */
      {
        gint i;

        msg.msg_iov = g_newa (struct iovec, num_vectors);
        for (i = 0; i < num_vectors; i++)
          {
            msg.msg_iov[i].iov_base = vectors[i].buffer;
            msg.msg_iov[i].iov_len = vectors[i].size;
          }
        msg.msg_iovlen = num_vectors;
      }

    /* control */
    msg.msg_control = g_alloca (2048);
    msg.msg_controllen = 2048;

    /* flags */
    if (flags != NULL)
      msg.msg_flags = *flags;
    else
      msg.msg_flags = 0;

    /* do it */
    while (1)
      {
        if (socket->priv->blocking &&
            !g_socket_condition_wait (socket,
                                      G_IO_IN, NULL, error))
          return -1;

        result = recvmsg (socket->priv->fd, &msg, msg.msg_flags);

        if (result < 0)
          {
            int errsv = get_socket_errno ();

            if (errsv == EINTR)
              continue;

            if (socket->priv->blocking &&
                (errsv == EWOULDBLOCK ||
                 errsv == EAGAIN))
              continue;

            g_set_error (error, G_IO_ERROR,
                         socket_io_error_from_errno (errsv),
                         _("Error receiving message: %s"), socket_strerror (errsv));

            return -1;
          }
        break;
      }

    /* decode address */
    if (address != NULL)
      {
        if (msg.msg_namelen > 0)
          *address = g_socket_address_new_from_native (msg.msg_name,
                                                       msg.msg_namelen);
        else
          *address = NULL;
      }

    /* decode control messages */
    {
      GSocketControlMessage **my_messages = NULL;
      gint allocated = 0, index = 0;
      const gchar *scm_pointer;
      struct cmsghdr *cmsg;
      gsize scm_size;

      scm_pointer = (const gchar *) msg.msg_control;
      scm_size = msg.msg_controllen;

      for (cmsg = CMSG_FIRSTHDR (&msg); cmsg; cmsg = CMSG_NXTHDR (&msg, cmsg))
        {
          GSocketControlMessage *message;

          message = g_socket_control_message_deserialize (cmsg->cmsg_level,
                                                          cmsg->cmsg_type,
                                                          cmsg->cmsg_len - ((char *)CMSG_DATA (cmsg) - (char *)cmsg),
                                                          CMSG_DATA (cmsg));
          if (message == NULL)
            /* We've already spewed about the problem in the
               deserialization code, so just continue */
            continue;

          if (index == allocated)
            {
              /* estimated 99% case: exactly 1 control message */
              allocated = MIN (allocated * 2, 1);
              my_messages = g_new (GSocketControlMessage *, (allocated + 1));
              allocated = 1;
            }

          my_messages[index++] = message;
        }

      if (num_messages)
        *num_messages = index;

      if (messages)
        {
          my_messages[index++] = NULL;
          *messages = my_messages;
        }
      else
        {
          gint i;

          /* free all those messages we just constructed.
           * we have to do it this way if the user ignores the
           * messages so that we will close any received fds.
           */
          for (i = 0; i < index; i++)
            g_object_unref (my_messages[i]);
          g_free (my_messages);
        }
    }

    /* capture the flags */
    if (flags != NULL)
      *flags = msg.msg_flags;

    return result;
  }
#else
  {
    struct sockaddr_storage addr;
    int addrlen;
    DWORD bytes_received;
    DWORD win_flags;
    int result;
    WSABUF *bufs;
    gint i;

    /* iov */
    bufs = g_newa (WSABUF, num_vectors);
    for (i = 0; i < num_vectors; i++)
      {
        bufs[i].buf = (char *)vectors[i].buffer;
        bufs[i].len = (gulong)vectors[i].size;
      }

    /* flags */
    if (flags != NULL)
      win_flags = *flags;
    else
      win_flags = 0;

    /* do it */
    while (1)
      {
        if (socket->priv->blocking &&
            !g_socket_condition_wait (socket,
                                      G_IO_IN, NULL, error))
          return -1;

        addrlen = sizeof addr;
        if (address)
          result = WSARecvFrom (socket->priv->fd,
                                bufs, num_vectors,
                                &bytes_received, &win_flags,
                                (struct sockaddr *)&addr, &addrlen,
                                NULL, NULL);
        else
          result = WSARecv (socket->priv->fd,
                            bufs, num_vectors,
                            &bytes_received, &win_flags,
                            NULL, NULL);
        if (result != 0)
          {
            int errsv = get_socket_errno ();

            if (errsv == WSAEINTR)
              continue;

            win32_unset_event_mask (socket, FD_READ);

            if (socket->priv->blocking &&
                errsv == WSAEWOULDBLOCK)
              continue;

            g_set_error (error, G_IO_ERROR,
                         socket_io_error_from_errno (errsv),
                         _("Error receiving message: %s"), socket_strerror (errsv));

            return -1;
          }
        win32_unset_event_mask (socket, FD_READ);
        break;
      }

    /* decode address */
    if (address != NULL)
      {
        if (addrlen > 0)
          *address = g_socket_address_new_from_native (&addr, addrlen);
        else
          *address = NULL;
      }

    /* capture the flags */
    if (flags != NULL)
      *flags = win_flags;

    return bytes_received;
  }
#endif
}

#define __G_SOCKET_C__
#include "gioaliasdef.c"