glib/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 "gsocket.h"

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

#ifndef G_OS_WIN32
# include <fcntl.h>
# include <unistd.h>
#endif

#ifdef HAVE_SYS_UIO_H
#include <sys/uio.h>
#endif

#include "gcancellable.h"
#include "gioenumtypes.h"
#include "ginetaddress.h"
#include "ginitable.h"
#include "gioerror.h"
#include "gioenums.h"
#include "gioerror.h"
#include "gnetworkingprivate.h"
#include "gsocketaddress.h"
#include "gsocketcontrolmessage.h"
#include "gcredentials.h"
#include "glibintl.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.
 *
 * Note that creating a #GSocket causes the signal %SIGPIPE to be
 * ignored for the remainder of the program. If you are writing a
 * command-line utility that uses #GSocket, you may need to take into
 * account the fact that your program will not automatically be killed
 * if it tries to write to %stdout after it has been closed.
 *
 * 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,
  PROP_TIMEOUT
};

struct _GSocketPrivate
{
  GSocketFamily   family;
  GSocketType     type;
  GSocketProtocol protocol;
  gint            fd;
  gint            listen_backlog;
  guint           timeout;
  GError         *construct_error;
  guint           inited : 1;
  guint           blocking : 1;
  guint           keepalive : 1;
  guint           closed : 1;
  guint           connected : 1;
  guint           listening : 1;
  guint           timed_out : 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 last_msg = G_STATIC_PRIVATE_INIT;
  char *msg;

  msg = g_win32_error_message (err);
  g_static_private_set (&last_msg, msg, g_free);

  return msg;
#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_literal (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;
    }

  if (socket->priv->timed_out)
    {
      socket->priv->timed_out = FALSE;
      g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_TIMED_OUT,
			   _("Socket I/O timed out"));
      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
  /* See bug #611756 */
  BOOL bool_val = FALSE;
#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)
    {
      addrlen = sizeof address;
      if (getpeername (fd, (struct sockaddr *) &address, &addrlen) >= 0)
	socket->priv->connected = TRUE;
    }

  optlen = sizeof bool_val;
  if (getsockopt (fd, SOL_SOCKET, SO_KEEPALIVE,
		  (void *)&bool_val, &optlen) == 0)
    {
#ifndef G_OS_WIN32
      /* Experimentation indicates that the SO_KEEPALIVE value is
       * actually a char on Windows, even if documentation claims it
       * to be a BOOL which is a typedef for int. So this g_assert()
       * fails. See bug #611756.
       */
      g_assert (optlen == sizeof bool_val);
#endif
      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 gint
g_socket_create_socket (GSocketFamily   family,
			GSocketType     type,
			int             protocol,
			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 == -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
  fd = socket (family, native_type | SOCK_CLOEXEC, protocol);
  /* It's possible that libc has SOCK_CLOEXEC but the kernel does not */
  if (fd < 0 && errno == EINVAL)
#endif
    fd = socket (family, native_type, protocol);

  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);
  GSocketAddress *address;

  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_enum (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:
	address = g_socket_get_local_address (socket, NULL);
	g_value_take_object (value, address);
	break;

      case PROP_REMOTE_ADDRESS:
	address = g_socket_get_remote_address (socket, NULL);
	g_value_take_object (value, address);
	break;

      case PROP_TIMEOUT:
	g_value_set_uint (value, socket->priv->timeout);
	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_enum (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;

      case PROP_TIMEOUT:
	g_socket_set_timeout (socket, g_value_get_uint (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
  if (socket->priv->event != WSA_INVALID_EVENT)
    {
      WSACloseEvent (socket->priv->event);
      socket->priv->event = WSA_INVALID_EVENT;
    }

  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_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 ();

#ifdef SIGPIPE
  /* There is no portable, thread-safe way to avoid having the process
   * be killed by SIGPIPE when calling send() or sendmsg(), so we are
   * forced to simply ignore the signal process-wide.
   */
  signal (SIGPIPE, SIG_IGN);
#endif

  g_type_class_add_private (klass, sizeof (GSocketPrivate));

  gobject_class->finalize = g_socket_finalize;
  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_enum ("protocol",
						      P_("Socket protocol"),
						      P_("The id of the protocol to use, or -1 for unknown"),
						      G_TYPE_SOCKET_PROTOCOL,
						      G_SOCKET_PROTOCOL_UNKNOWN,
						      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));

  /**
   * GSocket:timeout:
   *
   * The timeout in seconds on socket I/O
   *
   * Since: 2.26
   */
  g_object_class_install_property (gobject_class, PROP_TIMEOUT,
				   g_param_spec_uint ("timeout",
						      P_("Timeout"),
						      P_("The timeout in seconds on socket I/O"),
						      0,
						      G_MAXUINT,
						      0,
						      G_PARAM_READWRITE |
						      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;
#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_literal (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: 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 0 (%G_SOCKET_PROTOCOL_DEFAULT) 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. #GSocketProtocol lists several common ones.
 * 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.
 *
 * The protocol id is passed directly to the operating
 * system, so you can use protocols not listed in #GSocketProtocol if you
 * know the protocol number used for it.
 *
 * 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,
	      GSocketProtocol   protocol,
	      GError          **error)
{
  return G_SOCKET (g_initable_new (G_TYPE_SOCKET,
				   NULL, error,
				   "family", family,
				   "type", type,
				   "protocol", protocol,
				   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: Value for the keepalive flag
 *
 * Sets or unsets the %SO_KEEPALIVE flag on the underlying socket. When
 * this flag is set on a socket, the system will attempt to verify that the
 * remote socket endpoint is still present if a sufficiently long period of
 * time passes with no data being exchanged. If the system is unable to
 * verify the presence of the remote endpoint, it will automatically close
 * the connection.
 *
 * This option is only functional on certain kinds of sockets. (Notably,
 * %G_SOCKET_PROTOCOL_TCP sockets.)
 *
 * The exact time between pings is system- and protocol-dependent, but will
 * normally be at least two hours. Most commonly, you would set this flag
 * on a server socket if you want to allow clients to remain idle for long
 * periods of time, but also want to ensure that connections are eventually
 * garbage-collected if clients crash or become unreachable.
 *
 * 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.
 *
 * Note that this must be called before g_socket_listen() and has no
 * effect if called after that.
 *
 * Since: 2.22
 */
void
g_socket_set_listen_backlog (GSocket *socket,
			     gint     backlog)
{
  g_return_if_fail (G_IS_SOCKET (socket));
  g_return_if_fail (!socket->priv->listening);

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

/**
 * g_socket_get_timeout:
 * @socket: a #GSocket.
 *
 * Gets the timeout setting of the socket. For details on this, see
 * g_socket_set_timeout().
 *
 * Returns: the timeout in seconds
 *
 * Since: 2.26
 */
guint
g_socket_get_timeout (GSocket *socket)
{
  g_return_val_if_fail (G_IS_SOCKET (socket), 0);

  return socket->priv->timeout;
}

/**
 * g_socket_set_timeout:
 * @socket: a #GSocket.
 * @timeout: the timeout for @socket, in seconds, or 0 for none
 *
 * Sets the time in seconds after which I/O operations on @socket will
 * time out if they have not yet completed.
 *
 * On a blocking socket, this means that any blocking #GSocket
 * operation will time out after @timeout seconds of inactivity,
 * returning %G_IO_ERROR_TIMED_OUT.
 *
 * On a non-blocking socket, calls to g_socket_condition_wait() will
 * also fail with %G_IO_ERROR_TIMED_OUT after the given time. Sources
 * created with g_socket_create_source() will trigger after
 * @timeout seconds of inactivity, with the requested condition
 * set, at which point calling g_socket_receive(), g_socket_send(),
 * g_socket_check_connect_result(), etc, will fail with
 * %G_IO_ERROR_TIMED_OUT.
 *
 * If @timeout is 0 (the default), operations will never time out
 * on their own.
 *
 * Note that if an I/O operation is interrupted by a signal, this may
 * cause the timeout to be reset.
 *
 * Since: 2.26
 */
void
g_socket_set_timeout (GSocket *socket,
		      guint    timeout)
{
  g_return_if_fail (G_IS_SOCKET (socket));

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

/**
 * 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:
 * @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
 */
GSocketProtocol
g_socket_get_protocol (GSocket *socket)
{
  g_return_val_if_fail (G_IS_SOCKET (socket), -1);

  return 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,
 * either explicitly or implicitly when connecting.
 *
 * Returns: a #GSocketAddress or %NULL on error.
 *     Free the returned object with g_object_unref().
 *
 * Since: 2.22
 */
GSocketAddress *
g_socket_get_local_address (GSocket  *socket,
			    GError  **error)
{
  struct sockaddr_storage buffer;
  guint32 len = sizeof (buffer);

  g_return_val_if_fail (G_IS_SOCKET (socket), NULL);

  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;
    }

  return g_socket_address_new_from_native (&buffer, len);
}

/**
 * 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.
 *     Free the returned object with g_object_unref().
 *
 * Since: 2.22
 */
GSocketAddress *
g_socket_get_remote_address (GSocket  *socket,
			     GError  **error)
{
  struct sockaddr_storage buffer;
  guint32 len = sizeof (buffer);

  g_return_val_if_fail (G_IS_SOCKET (socket), NULL);

  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;
    }

  return g_socket_address_new_from_native (&buffer, len);
}

/**
 * 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->connected;
}

/**
 * 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().
 *
 * To set the maximum amount of outstanding clients, use
 * g_socket_set_listen_backlog().
 *
 * 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;
    }

  socket->priv->listening = TRUE;

  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() ).
 * In certain situations, you may also want to bind a socket that will be
 * used to initiate connections, though this is not normally required.
 *
 * @allow_reuse should be %TRUE for server sockets (sockets that you will
 * eventually call g_socket_accept() on), and %FALSE for client sockets.
 * (Specifically, if it is %TRUE, then g_socket_bind() will set the
 * %SO_REUSEADDR flag on the socket, allowing it to bind @address even if
 * that address was previously used by another socket that has not yet been
 * fully cleaned-up by the kernel. Failing to set this flag on a server
 * socket may cause the bind call to return %G_IO_ERROR_ADDRESS_IN_USE if
 * the server program is stopped and then immediately restarted.)
 *
 * Returns: %TRUE on success, %FALSE on error.
 *
 * Since: 2.22
 */
gboolean
g_socket_bind (GSocket         *socket,
	       GSocketAddress  *address,
	       gboolean         reuse_address,
	       GError         **error)
{
  struct sockaddr_storage addr;

  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
  {
    int value;

    value = (int) !!reuse_address;
    /* Ignore errors here, the only likely error is "not supported", and
       this is a "best effort" thing mainly */
    setsockopt (socket->priv->fd, SOL_SOCKET, SO_REUSEADDR,
		(gpointer) &value, sizeof (value));
  }
#endif

  if (!g_socket_address_to_native (address, &addr, sizeof addr, error))
    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;
    }

  return TRUE;
}

/**
 * g_socket_speaks_ipv4:
 * @socket: a #GSocket
 *
 * Checks if a socket is capable of speaking IPv4.
 *
 * IPv4 sockets are capable of speaking IPv4.  On some operating systems
 * and under some combinations of circumstances IPv6 sockets are also
 * capable of speaking IPv4.  See RFC 3493 section 3.7 for more
 * information.
 *
 * No other types of sockets are currently considered as being capable
 * of speaking IPv4.
 *
 * Returns: %TRUE if this socket can be used with IPv4.
 *
 * Since: 2.22
 **/
gboolean
g_socket_speaks_ipv4 (GSocket *socket)
{
  switch (socket->priv->family)
    {
    case G_SOCKET_FAMILY_IPV4:
      return TRUE;

    case G_SOCKET_FAMILY_IPV6:
#if defined (IPPROTO_IPV6) && defined (IPV6_V6ONLY)
      {
        guint sizeof_int = sizeof (int);
        gint v6_only;

        if (getsockopt (socket->priv->fd,
                        IPPROTO_IPV6, IPV6_V6ONLY,
                        &v6_only, &sizeof_int) != 0)
          return FALSE;

        return !v6_only;
      }
#else
      return FALSE;
#endif

    default:
      return FALSE;
    }
}

/**
 * g_socket_accept:
 * @socket: a #GSocket.
 * @cancellable: a %GCancellable or %NULL
 * @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,
		 GCancellable  *cancellable,
		 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 (TRUE)
    {
      if (socket->priv->blocking &&
	  !g_socket_condition_wait (socket,
				    G_IO_IN, cancellable, 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.
 * @cancellable: a %GCancellable or %NULL
 * @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_connect_result().
 *
 * Returns: %TRUE if connected, %FALSE on error.
 *
 * Since: 2.22
 */
gboolean
g_socket_connect (GSocket         *socket,
		  GSocketAddress  *address,
		  GCancellable    *cancellable,
		  GError         **error)
{
  struct sockaddr_storage buffer;

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

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

  if (!g_socket_address_to_native (address, &buffer, sizeof buffer, error))
    return FALSE;

  while (1)
    {
      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 == WSAEWOULDBLOCK)
#endif
	    {
	      if (socket->priv->blocking)
		{
		  if (g_socket_condition_wait (socket, G_IO_OUT, cancellable, error))
		    {
		      if (g_socket_check_connect_result (socket, error))
			break;
		    }
		  g_prefix_error (error, _("Error connecting: "));
		}
	      else
                g_set_error_literal (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->connected = TRUE;

  return TRUE;
}

/**
 * g_socket_check_connect_result:
 * @socket: a #GSocket
 * @error: #GError for error reporting, or %NULL to ignore.
 *
 * Checks and resets the pending connect error for the socket.
 * This is 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_connect_result (GSocket  *socket,
			       GError  **error)
{
  guint optlen;
  int value;

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

  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_literal (error, G_IO_ERROR, socket_io_error_from_errno (value),
                           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 @size
 *     bytes long).
 * @size: the number of bytes you want to read from the socket
 * @cancellable: a %GCancellable or %NULL
 * @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.
 *
 * For %G_SOCKET_TYPE_DATAGRAM and %G_SOCKET_TYPE_SEQPACKET sockets,
 * g_socket_receive() will always read either 0 or 1 complete messages from
 * the socket. If the received message is too large to fit in @buffer, then
 * the data beyond @size bytes will be discarded, without any explicit
 * indication that this has occurred.
 *
 * For %G_SOCKET_TYPE_STREAM sockets, g_socket_receive() can return any
 * number of bytes, up to @size. If more than @size bytes have been
 * received, the additional data will be returned in future calls to
 * g_socket_receive().
 *
 * 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 when data is available, 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,
		  GCancellable  *cancellable,
		  GError       **error)
{
  gssize ret;

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

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

  if (g_cancellable_set_error_if_cancelled (cancellable, error))
    return -1;

  while (1)
    {
      if (socket->priv->blocking &&
	  !g_socket_condition_wait (socket,
				    G_IO_IN, cancellable, 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 @size
 *     bytes long).
 * @size: the number of bytes you want to read from the socket
 * @cancellable: a %GCancellable or %NULL
 * @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.
 *
 * See g_socket_receive() for additional information.
 *
 * 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,
		       GCancellable    *cancellable,
		       GError         **error)
{
  GInputVector v;

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

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

/* Although we ignore SIGPIPE, gdb will still stop if the app receives
 * one, which can be confusing and annoying. So if possible, we want
 * to suppress the signal entirely.
 */
#ifdef MSG_NOSIGNAL
#define G_SOCKET_DEFAULT_SEND_FLAGS MSG_NOSIGNAL
#else
#define G_SOCKET_DEFAULT_SEND_FLAGS 0
#endif

/**
 * g_socket_send:
 * @socket: a #GSocket
 * @buffer: the buffer containing the data to send.
 * @size: the number of bytes to send
 * @cancellable: a %GCancellable or %NULL
 * @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 when space is available, wait for the
 * %G_IO_OUT condition. Note though that you may still receive
 * %G_IO_ERROR_WOULD_BLOCK from g_socket_send() even if you were previously
 * notified of a %G_IO_OUT condition. (On Windows in particular, this is
 * very common due to the way the underlying APIs work.)
 *
 * On error -1 is returned and @error is set accordingly.
 *
 * Returns: Number of bytes written (which may be less than @size), or -1
 * on error
 *
 * Since: 2.22
 */
gssize
g_socket_send (GSocket       *socket,
	       const gchar   *buffer,
	       gsize          size,
	       GCancellable  *cancellable,
	       GError       **error)
{
  gssize ret;

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

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

  if (g_cancellable_set_error_if_cancelled (cancellable, error))
    return -1;

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

      if ((ret = send (socket->priv->fd, buffer, size, G_SOCKET_DEFAULT_SEND_FLAGS)) < 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
 * @cancellable: a %GCancellable or %NULL
 * @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()).
 *
 * See g_socket_send() for additional information.
 *
 * Returns: Number of bytes written (which may be less than @size), or -1
 * on error
 *
 * Since: 2.22
 */
gssize
g_socket_send_to (GSocket         *socket,
		  GSocketAddress  *address,
		  const gchar     *buffer,
		  gsize            size,
		  GCancellable    *cancellable,
		  GError         **error)
{
  GOutputVector v;

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

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

/**
 * g_socket_shutdown:
 * @socket: a #GSocket
 * @shutdown_read: whether to shut down the read side
 * @shutdown_write: whether to shut down the write side
 * @error: #GError for error reporting, or %NULL to ignore.
 *
 * Shut down part of a full-duplex connection.
 *
 * If @shutdown_read is %TRUE then the recieving side of the connection
 * is shut down, and further reading is disallowed.
 *
 * If @shutdown_write is %TRUE then the sending side of the connection
 * is shut down, and further writing is disallowed.
 *
 * It is allowed for both @shutdown_read and @shutdown_write to be %TRUE.
 *
 * One example where this is used is graceful disconnect for TCP connections
 * where you close the sending side, then wait for the other side to close
 * the connection, thus ensuring that the other side saw all sent data.
 *
 * Returns: %TRUE on success, %FALSE on error
 *
 * Since: 2.22
 */
gboolean
g_socket_shutdown (GSocket   *socket,
		   gboolean   shutdown_read,
		   gboolean   shutdown_write,
		   GError   **error)
{
  int how;

  g_return_val_if_fail (G_IS_SOCKET (socket), TRUE);

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

  /* Do nothing? */
  if (!shutdown_read && !shutdown_write)
    return TRUE;

#ifndef G_OS_WIN32
  if (shutdown_read && shutdown_write)
    how = SHUT_RDWR;
  else if (shutdown_read)
    how = SHUT_RD;
  else
    how = SHUT_WR;
#else
  if (shutdown_read && shutdown_write)
    how = SD_BOTH;
  else if (shutdown_read)
    how = SD_RECEIVE;
  else
    how = SD_SEND;
#endif

  if (shutdown (socket->priv->fd, how) != 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));
      return FALSE;
    }

  if (shutdown_read && shutdown_write)
    socket->priv->connected = FALSE;

  return TRUE;
}

/**
 * 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 socket 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.
 *
 * Beware that due to the way that TCP works, it is possible for
 * recently-sent data to be lost if either you close a socket while the
 * %G_IO_IN condition is set, or else if the remote connection tries to
 * send something to you after you close the socket but before it has
 * finished reading all of the data you sent. There is no easy generic
 * way to avoid this problem; the easiest fix is to design the network
 * protocol such that the client will never send data "out of turn".
 * Another solution is for the server to half-close the connection by
 * calling g_socket_shutdown() with only the @shutdown_write flag set,
 * and then wait for the client to notice this and close its side of the
 * connection, after which the server can safely call g_socket_close().
 * (This is what #GTcpConnection does if you call
 * g_tcp_connection_set_graceful_disconnect(). But of course, this
 * only works if the client will close its connection after the server
 * does.)
 *
 * 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;
    }

  socket->priv->connected = FALSE;
  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;
}
#endif

typedef struct {
  GSource       source;
  GPollFD       pollfd;
  GSocket      *socket;
  GIOCondition  condition;
  GCancellable *cancellable;
  GPollFD       cancel_pollfd;
  GTimeVal      timeout_time;
} GSocketSource;

static gboolean
socket_source_prepare (GSource *source,
		       gint    *timeout)
{
  GSocketSource *socket_source = (GSocketSource *)source;

  if (g_cancellable_is_cancelled (socket_source->cancellable))
    return TRUE;

  if (socket_source->timeout_time.tv_sec)
    {
      GTimeVal now;

      g_source_get_current_time (source, &now);
      *timeout = ((socket_source->timeout_time.tv_sec - now.tv_sec) * 1000 +
		  (socket_source->timeout_time.tv_usec - now.tv_usec) / 1000);
      if (*timeout < 0)
	{
	  socket_source->socket->priv->timed_out = TRUE;
	  socket_source->pollfd.revents = socket_source->condition & (G_IO_IN | G_IO_OUT);
	  return TRUE;
	}
    }
  else
    *timeout = -1;

#ifdef G_OS_WIN32
  socket_source->pollfd.revents = update_condition (socket_source->socket);
#endif

  if ((socket_source->condition & socket_source->pollfd.revents) != 0)
    return TRUE;

  return FALSE;
}

static gboolean
socket_source_check (GSource *source)
{
  int timeout;

  return socket_source_prepare (source, &timeout);
}

static gboolean
socket_source_dispatch (GSource     *source,
			GSourceFunc  callback,
			gpointer     user_data)
{
  GSocketSourceFunc func = (GSocketSourceFunc)callback;
  GSocketSource *socket_source = (GSocketSource *)source;

  return (*func) (socket_source->socket,
		  socket_source->pollfd.revents & socket_source->condition,
		  user_data);
}

static void
socket_source_finalize (GSource *source)
{
  GSocketSource *socket_source = (GSocketSource *)source;
  GSocket *socket;

  socket = socket_source->socket;

#ifdef G_OS_WIN32
  remove_condition_watch (socket, &socket_source->condition);
#endif

  g_object_unref (socket);

  if (socket_source->cancellable)
    {
      g_cancellable_release_fd (socket_source->cancellable);
      g_object_unref (socket_source->cancellable);
    }
}

static GSourceFuncs socket_source_funcs =
{
  socket_source_prepare,
  socket_source_check,
  socket_source_dispatch,
  socket_source_finalize
};

static GSource *
socket_source_new (GSocket      *socket,
		   GIOCondition  condition,
		   GCancellable *cancellable)
{
  GSource *source;
  GSocketSource *socket_source;

#ifdef G_OS_WIN32
  ensure_event (socket);

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

  condition |= G_IO_HUP | G_IO_ERR;

  source = g_source_new (&socket_source_funcs, sizeof (GSocketSource));
  g_source_set_name (source, "GSocket");
  socket_source = (GSocketSource *)source;

  socket_source->socket = g_object_ref (socket);
  socket_source->condition = condition;

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

#ifdef G_OS_WIN32
  add_condition_watch (socket, &socket_source->condition);
  socket_source->pollfd.fd = (gintptr) socket->priv->event;
#else
  socket_source->pollfd.fd = socket->priv->fd;
#endif

  socket_source->pollfd.events = condition;
  socket_source->pollfd.revents = 0;
  g_source_add_poll (source, &socket_source->pollfd);

  if (socket->priv->timeout)
    {
      g_get_current_time (&socket_source->timeout_time);
      socket_source->timeout_time.tv_sec += socket->priv->timeout;
    }
  else
    {
      socket_source->timeout_time.tv_sec = 0;
      socket_source->timeout_time.tv_usec = 0;
    }

  return source;
}

/**
 * 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 (which
 * is likely 0 unless cancellation happened at the same time as a
 * condition change). You can check for this in the callback using
 * g_cancellable_is_cancelled().
 *
 * If @socket has a timeout set, and it is reached before @condition
 * occurs, the source will then trigger anyway, reporting %G_IO_IN or
 * %G_IO_OUT depending on @condition. However, @socket will have been
 * marked as having had a timeout, and so the next #GSocket I/O method
 * you call will then fail with a %G_IO_ERROR_TIMED_OUT.
 *
 * Returns: a newly allocated %GSource, free with g_source_unref().
 *
 * Since: 2.22
 */
GSource *
g_socket_create_source (GSocket      *socket,
			GIOCondition  condition,
			GCancellable *cancellable)
{
  g_return_val_if_fail (G_IS_SOCKET (socket) && (cancellable == NULL || G_IS_CANCELLABLE (cancellable)), NULL);

  return socket_source_new (socket, condition, cancellable);
}

/**
 * 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.
 *
 * Note that on Windows, it is possible for an operation to return
 * %G_IO_ERROR_WOULD_BLOCK even immediately after
 * g_socket_condition_check() has claimed that the socket is ready for
 * writing. Rather than calling g_socket_condition_check() and then
 * writing to the socket if it succeeds, it is generally better to
 * simply try writing to the socket right away, and try again later if
 * the initial attempt returns %G_IO_ERROR_WOULD_BLOCK.
 *
 * 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
 * is met, %TRUE is returned.
 *
 * If @cancellable is cancelled before the condition is met, or if the
 * socket has a timeout set and it is reached before the condition is
 * met, then %FALSE is returned and @error, if non-%NULL, is set to
 * the appropriate value (%G_IO_ERROR_CANCELLED or
 * %G_IO_ERROR_TIMED_OUT).
 *
 * 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, timeout;
    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 (g_cancellable_make_pollfd (cancellable, &cancel_fd))
      events[num_events++] = (WSAEVENT)cancel_fd.fd;

    if (socket->priv->timeout)
      timeout = socket->priv->timeout * 1000;
    else
      timeout = WSA_INFINITE;

    current_condition = update_condition (socket);
    while ((condition & current_condition) == 0)
      {
	res = WSAWaitForMultipleEvents(num_events, events,
				       FALSE, timeout, 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;
	  }
	else if (res == WSA_WAIT_TIMEOUT)
	  {
	    g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_TIMED_OUT,
				 _("Socket I/O timed out"));
	    break;
	  }

	if (g_cancellable_set_error_if_cancelled (cancellable, error))
	  break;

	current_condition = update_condition (socket);
      }
    remove_condition_watch (socket, &condition);
    if (num_events > 1)
      g_cancellable_release_fd (cancellable);

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

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

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

    if (socket->priv->timeout)
      timeout = socket->priv->timeout * 1000;
    else
      timeout = -1;

    do
      result = g_poll (poll_fd, num, timeout);
    while (result == -1 && get_socket_errno () == EINTR);
    
    if (num > 1)
      g_cancellable_release_fd (cancellable);

    if (result == 0)
      {
	g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_TIMED_OUT,
			     _("Socket I/O timed out"));
	return FALSE;
      }

    return !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
 * @cancellable: a %GCancellable or %NULL
 * @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()).
 *
 * @vectors must point to an array of #GOutputVector structs and
 * @num_vectors must be the length of this array. (If @num_vectors is -1,
 * then @vectors is assumed to be terminated by a #GOutputVector with a
 * %NULL buffer pointer.) The #GOutputVector structs describe the buffers
 * that the sent data will be gathered from. Using multiple
 * #GOutputVector<!-- -->s is more memory-efficient than manually copying
 * data from multiple sources into a single buffer, and more
 * network-efficient than making multiple calls to g_socket_send().
 *
 * @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 is sent. The commonly available arguments
 * for this are 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 when space is available, wait for the
 * %G_IO_OUT condition. Note though that you may still receive
 * %G_IO_ERROR_WOULD_BLOCK from g_socket_send() even if you were previously
 * notified of a %G_IO_OUT condition. (On Windows in particular, this is
 * very common due to the way the underlying APIs work.)
 *
 * On error -1 is returned and @error is set accordingly.
 *
 * Returns: Number of bytes written (which may be less than @size), 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,
		       GCancellable           *cancellable,
		       GError                **error)
{
  GOutputVector one_vector;
  char zero;

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

  if (g_cancellable_set_error_if_cancelled (cancellable, 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);
	if (!g_socket_address_to_native (address, msg.msg_name, msg.msg_namelen, error))
	  return -1;
      }
    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 (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, cancellable, error))
	  return -1;

	result = sendmsg (socket->priv->fd, &msg, flags | G_SOCKET_DEFAULT_SEND_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_literal (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 */
    addrlen = 0; /* Avoid warning */
    if (address)
      {
	addrlen = g_socket_address_get_native_size (address);
	if (!g_socket_address_to_native (address, &addr, sizeof addr, error))
	  return -1;
      }

    while (1)
      {
	if (socket->priv->blocking &&
	    !g_socket_condition_wait (socket,
				      G_IO_OUT, cancellable, 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 may 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
 * @cancellable: a %GCancellable or %NULL
 * @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_vectors is -1, then @vectors is assumed to be terminated
 * by a #GInputVector with a %NULL buffer pointer.
 *
 * As a special case, if @num_vectors is 0 (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, will be set to point to a newly-allocated
 * array of #GSocketControlMessage instances or %NULL if no such
 * messages was received. 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() after calling g_object_unref() on each
 * element. If @messages is %NULL, any control messages received will
 * be discarded.
 *
 * @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 are 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
 * (and g_socket_receive_message() may pass system-specific flags out).
 *
 * As with g_socket_receive(), data may be discarded if @socket is
 * %G_SOCKET_TYPE_DATAGRAM or %G_SOCKET_TYPE_SEQPACKET and you do not
 * provide enough buffer space to read a complete message. You can pass
 * %G_SOCKET_MSG_PEEK in @flags to peek at the current message without
 * removing it from the receive queue, but there is no portable way to find
 * out the length of the message other than by reading it into a
 * sufficiently-large buffer.
 *
 * 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 when
 * data is available, 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,
			  GCancellable            *cancellable,
			  GError                 **error)
{
  GInputVector one_vector;
  char one_byte;

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

  if (g_cancellable_set_error_if_cancelled (cancellable, 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, cancellable, 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 */
    {
      GPtrArray *my_messages = NULL;
      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 (messages == NULL)
	    {
	      /* we have to do it this way if the user ignores the
	       * messages so that we will close any received fds.
	       */
	      g_object_unref (message);
	    }
	  else
	    {
	      if (my_messages == NULL)
		my_messages = g_ptr_array_new ();
	      g_ptr_array_add (my_messages, message);
	    }
	}

      if (num_messages)
	*num_messages = my_messages != NULL ? my_messages->len : 0;

      if (messages)
	{
	  if (my_messages == NULL)
	    {
	      *messages = NULL;
	    }
	  else
	    {
	      g_ptr_array_add (my_messages, NULL);
	      *messages = (GSocketControlMessage **) g_ptr_array_free (my_messages, FALSE);
	    }
	}
      else
	{
	  g_assert (my_messages == NULL);
	}
    }

    /* 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, cancellable, 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;

    if (messages != NULL)
      *messages = NULL;
    if (num_messages != NULL)
      *num_messages = 0;

    return bytes_received;
  }
#endif
}

/**
 * g_socket_get_credentials:
 * @socket: a #GSocket.
 * @error: #GError for error reporting, or %NULL to ignore.
 *
 * Returns the credentials of the foreign process connected to this
 * socket, if any (e.g. it is only supported for %G_SOCKET_FAMILY_UNIX
 * sockets).
 *
 * If this operation isn't supported on the OS, the method fails with
 * the %G_IO_ERROR_NOT_SUPPORTED error. On Linux this is implemented
 * by reading the %SO_PEERCRED option on the underlying socket.
 *
 * Other ways to obtain credentials from a foreign peer includes the
 * #GUnixCredentialsMessage type and
 * g_unix_connection_send_credentials() /
 * g_unix_connection_receive_credentials() functions.
 *
 * Returns: %NULL if @error is set, otherwise a #GCredentials object
 * that must be freed with g_object_unref().
 *
 * Since: 2.26
 */
GCredentials *
g_socket_get_credentials (GSocket   *socket,
                          GError   **error)
{
  GCredentials *ret;

  g_return_val_if_fail (G_IS_SOCKET (socket), NULL);
  g_return_val_if_fail (error == NULL || *error == NULL, NULL);

  ret = NULL;

#ifdef __linux__
  {
    struct ucred native_creds;
    socklen_t optlen;
    optlen = sizeof (struct ucred);
    if (getsockopt (socket->priv->fd,
                    SOL_SOCKET,
                    SO_PEERCRED,
                    (void *)&native_creds,
                    &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));
      }
    else
      {
        ret = g_credentials_new ();
        g_credentials_set_native (ret,
                                  G_CREDENTIALS_TYPE_LINUX_UCRED,
                                  &native_creds);
      }
  }
#else
  g_set_error_literal (error,
                       G_IO_ERROR,
                       G_IO_ERROR_NOT_SUPPORTED,
                       _("g_socket_get_credentials not implemented for this OS"));
#endif

  return ret;
}